Lynn Nadel

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Scholarly Contributions

Books

• Nadel, L., & Sinnott-Armstrong, W. (2012). Memory and Law. New York: Oxford University Press.
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  Eds.
• Waller, D., & Nadel, L. (2012). The APA Handbook of Spatial Cognition. Washington DC: APA.
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  Eds.

Chapters

• Hoscheidt, S., Dongaonkar, B., Payne, J., & Nadel, L. (2013). Emotion, stress, and memory. In Oxford Handbook of Cognitive Psychology(pp pp. 557-570). N.Y.: Oxford University Press.
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  In Reisberg, D. (Ed.), Oxford Handbook of Cognitive Psychology
• Nadel, L., & Sinnott-Armstrong, W. (2012). Memory in the legal context. In Memory and Law. New York: Oxford University Press.
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  In Nadel, L. & Sinnott-Armstrong, W. (Eds.)
• Nadel, L. -. (2007). Consolidation: The demise of the fixed trace.. Oxford University Press.
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  ;Your Role: Wrote it.;Full Citation: Nadel, L. Consolidation: The demise of the fixed trace. In Science of Memory: Concepts, Roediger, H.L., Dudai, Y. and Fitzpatrick, S. (Eds.), pp. 177-181, Oxford University Press, 2007.;
• Nadel, L. -. (2006). Neuropsychological Aspects of Down Syndrome. John Wiley & Sons.
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  ;Your Role: Wrote it.;Full Citation: Nadel, L. Neuropsychological Aspects of Down Syndrome, in Rondal, J.A and Perera, J. (Eds.) Down Syndrome Neurobehavioral Specificity, pp. 67-83, John Wiley & Sons, London, 2006.;
• Nadel, L. -., & Hupbach, A. (2006). Cross-species comparisons in development: The case of the spatial “module”. Oxford University Press.
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  ;Your Role: Wrote first draft, and developed many of the ideas contained in the chapter.;Full Citation: Nadel, L. and Hupbach, A. Cross-species comparisons in development: The case of the spatial “module”. In M.H. Johnson & Y. Munakata (eds). Attention and Performance XXI, pp. 499-511, Oxford, Oxford University Press, 2006.;Other collaborative: Yes;Specify other collaborative: Collaborative with post-doc.;
• Nadel, L. -., Moscovitch, M., Westmacott, R., Gilboa, A., Addis, D., Rosenbaum, R. S., Viskontas, I., Priselac, S., Svoboda, E., Ziegler, M., Black, S., Gao, F., Grady, C., Freedman, M., Kohler, S., Leach, L., Levine, B., McAndrews, M. P., Proulx, G., & Richards, . (2005). Hippocampal complex contribution to retention and retrieval of recent and remote episodic and semantic memories: Evidence from behavioral and neuroimaging studies of healthy and brain-damaged people. Springer-Verlag.
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  ;Your Role: Co-author of the initiating theory and some of the empirical work covered in the review; one of many who contributed to the drafting of the chapter and its final version.;Full Citation: Moscovitch, M., Westmacott, R., Gilboa, A., Addis, D., Rosenbaum, R.S., Viskontas, I., Priselac, S., Svoboda, E., Ziegler, M., Black, S., Gao, F., Grady, C., Freedman, M., Kohler, S., Leach, L., Levine, B., McAndrews, M.P., Nadel, L., Proulx, G., Richards, B., Ryan, L., Stokes, K., and Winocur, W. Hippocampal complex contribution to retention and retrieval of recent and remote episodic and semantic memories: Evidence from behavioral and neuroimaging studies of healthy and brain-damaged people, in Ohta, N., MacLeod, C. M., & Uttl, B. (Eds.) Dynamic cognitive processes, pp. 333-380, Tokyo: Springer-Verlag, 2005.;Other collaborative: Yes;Specify other collaborative: A review chapter co-authored by a host of people from several labs involved in the various aspects of work reviewed.;

Journals/Publications

• Evensmoen, H. R., Ladstein, J., Hansen, T. I., Møller, J. A., Witter, M. P., Nadel, L., & Håberg, A. K. (2015). From details to large scale: the representation of environmental positions follows a granularity gradient along the human hippocampal and entorhinal anterior-posterior axis. Hippocampus, 25(1), 119-35.
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  In rodents representations of environmental positions follow a granularity gradient along the hippocampal and entorhinal anterior-posterior axis; with fine-grained representations most posteriorly. To investigate if such a gradient exists in humans, functional magnetic resonance imaging data were acquired during virtual environmental learning of the objects' positions and the association between the objects and room geometry. The Objects-room geometry binding led to increased activation throughout the hippocampus and in the posterior entorhinal cortex. Within subject comparisons related specifically to the level of spatial granularity of the object position encoding showed that activation in the posterior and intermediate hippocampus was highest for fine-grained and medium-grained representations, respectively. In addition, the level of fine granularity in the objects' positions encoded between subjects correlated with posterior hippocampal activation. For the anterior hippocampus increased activation was observed for coarse-grained representations as compared to failed encoding. Activation in anterior hippocampus correlated with the number of environments in which the objects positions were remembered when permitting a coarse representation of positions. In the entorhinal cortex, activation in the posterior part correlated with level of fine granularity for the objects' positions encoded between subjects, and activation in the posterior and intermediate entorhinal cortex increased for medium-grained representations. This demonstrates directly that positional granularity is represented in a graded manner along the anterior-posterior axis of the human hippocampus, and to some extent entorhinal cortex, with most fine-grained positional representations posteriorly.
• Spano, G., Peterson, M. A., Nadel, L., Edgin, J. O., Spano, G., Peterson, M. A., Nadel, L., & Edgin, J. O. (2015). Seeing Can Be Remembering: Interactions Between Memory and Perception in Typical and Atypical Development.. Clinical Psychological Science.
• Breslin, J., Spano, G., Bootzin, R. R., Anand, P., Nadel, L., Edgin, J. O., Breslin, J., Spano, G., Bootzin, R. R., Anand, P., Nadel, L., & Edgin, J. O. (2014). Obstructive sleep apnea and cognition in Down Syndrome. Developmental Medicine & Child Neurology, 7, 657-664.
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  DOI: 10.1111/dmc.12376
• Breslin, J., Spanò, G., Bootzin, R., Anand, P., Nadel, L., Edgin, J., Breslin, J., Spanò, G., Bootzin, R., Anand, P., Nadel, L., Edgin, J., Breslin, J., Spanò, G., Bootzin, R., Anand, P., Nadel, L., & Edgin, J. (2014). Obstructive sleep apnea syndrome and cognition in Down syndrome. Developmental Medicine and Child Neurology.
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  Abstract: Aim: Good-quality sleep is essential for normal learning and memory. Sleep fragmentation and disrupted sleep architecture are commonly observed throughout the lifespan of individuals with Down syndrome, a condition marked by cognitive deficits emerging within the first few months of life. While obstructive sleep apnea syndrome (OSAS) is known to contribute to the loss of sleep quality in Down syndrome, its relation to cognitive and behavioral impairment remains poorly understood. Method: Using ambulatory polysomnography, we measured sleep in an unreferred community-based sample of 38 individuals with Down syndrome (15 males, 23 females; mean age 9y 7mo (SD 1y 9mo), range 7-12y). Cognitive outcomes were assessed with the Arizona Cognitive Test Battery, a set of psychometric measures designed and validated for this population. Results: Among children with Down syndrome, mean Verbal IQ score (p=0.006) was 9 points lower in those with comorbid OSAS (apnea-hypopnea index >1.5) than in those without OSAS, and performance on measures of cognitive flexibility was poorer (p=0.03). In addition, those with OSAS showed increased light-stage sleep (p=0.009) at the expense of slow-wave sleep (p=0.04). Interpretation: These findings demonstrate a relation between OSAS and cognitive outcomes in Down syndrome. More work is required to fully understand the mechanisms underlying the links between poor sleep and impaired cognitive function. Overall, these findings highlight the importance of adequate sleep in typically and atypically developing populations. What this paper adds: Obstructive sleep apnea syndrome is associated with some cognitive deficits in children with Down syndrome. Verbal IQ was 9 points lower in children with OSAS and Down syndrome, who also showed executive function deficits. These differences were found in children of similar age, BMI, and health status. Children with a dual diagnosis of Down syndrome and OSAS showed less slow-wave sleep and more light-stage sleep. © 2014 Mac Keith Press.
• Edgin, J. O., Spanò, G., Kawa, K., & Nadel, L. (2014). Remembering things without context: Development matters. Child Development.
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  Abstract: Spatial context supports memory retrieval in adults. To understand the development of these effects, context effects on object recognition were tested in neurotypical children ages 3 years to adulthood (n 3-6 years = 34, n 10-16 years = 32, n college age = 22) and individuals with Down syndrome (DS) ages 10-29 years (n = 21). Participants engaged in an object recognition task; objects were presented in scenes and either remained in that same scene or were removed at test. In some groups (< 4.5 years and with DS) context effects were present even though object recognition was poor. After 4.5 years, children demonstrated memory flexibility, while later in adolescence context effects reemerged, showing nonlinearity in the development of these effects. © 2014 Society for Research in Child Development, Inc.
• Lane, R. D., Ryan, L., Nadel, L., & Greenberg, L. (2014). Memory Reconsolidation, Emotional Arousal and the Process of Change in Psychotherapy: New Insights from Brain Science. The Behavioral and brain sciences, 1-80.
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  Since Freud clinicians have understood that disturbing memories contribute to psychopathology and that new emotional experiences contribute to therapeutic change. Yet, controversy remains about what is truly essential to bring about psychotherapeutic change. Mounting evidence from empirical studies suggests that emotional arousal is a key ingredient in therapeutic change in many modalities. In addition, memory seems to play an important role but there is a lack of consensus on the role of understanding what happened in the past in bringing about therapeutic change. The core idea of this paper is that therapeutic change in a variety of modalities, including behavioral therapy, cognitive-behavioral therapy, emotion-focused and psychodynamic psychotherapy, results from the updating of prior emotional memories through a process of reconsolidation that incorporates new emotional experiences. The authors present an integrative memory model with three interactive components - autobiographical (event) memories, semantic structures, and emotional responses - supported by emerging evidence from cognitive neuroscience on implicit and explicit emotion, implicit and explicit memory, emotion-memory interactions, memory reconsolidation, and the relationship between autobiographical and semantic memory. We propose that the essential ingredients of therapeutic change include: 1) reactivating old memories; 2) engaging in new emotional experiences that are incorporated into these reactivated memories via the process of reconsolidation; and 3) reinforcing the integrative memory structure by practicing a new way of behaving and experiencing the world in a variety of contexts. The implications of this new neurobiologically-grounded synthesis for research, clinical practice and teaching are discussed.
• Dongaonkar, B., Hupbach, A., Gomez, R., & Nadel, L. (2013). Effects of psychosocial stress on episodic memory updating. Psychopharmacology, 226(4), 769-779.
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  PMID: 23404063;Abstract: Rationale: When a consolidated memory is reactivated, it becomes labile and modifiable. Recently, updating of reactivated episodic memory was demonstrated by Hupbach et al. (Learn Mem 14:47-53, 2007). Memory updating involves two vital processes - reactivation followed by reconsolidation. Here, we explored effects of psychosocial stress on episodic memory updating. Based on prior research, we hypothesized that stress before reactivation or stress before reconsolidation would impair memory updating. Methods: Participants learned a set of objects (list 1) on day 1. On day 2, some participants were reminded of list 1 before learning a second set of objects (list 2). Memory for list 1 was tested on day 3. Stress was administered either before reactivation of list 1 on day 2 (exp 1) or before reconsolidation of list 1, i.e., after reactivation and learning list 2 on day 2 (exp 2). Results: Memory updating involves the incorporation of list 2 items into list 1 memory, contingent upon the reactivation of list 1 memory. In exp 1, the reminder groups had higher intrusions than the no-reminder groups, but contrary to our predictions, stress did not reduce this reminder effect. Stress effects were, however, found in exp 2: the reminder group that was stressed after reactivation and new learning showed fewer intrusions than the control reminder group. Conclusion: The findings suggest that stress before reactivation does not impair memory updating but stress at the onset of reconsolidation can. Timing may determine the effects of stress on memory processing. © 2013 Springer-Verlag Berlin Heidelberg.
• Fawcett, J. M., Taylor, T. L., & Nadel, L. (2013). Event-method directed forgetting: Forgetting a video segment is more effortful than remembering it. Acta Psychologica, 144(2), 332-343.
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  PMID: 23933003;Abstract: Videos were presented depicting events such as baking cookies or cleaning a fish tank. Periodically, the video paused and an instruction to Remember (R) or Forget (F) the preceding video segment was presented; the video then resumed. Participants later responded more accurately to cued-recall questions (E1) and to true/false statements (E2-5) regarding R segments than F segments. This difference was larger for specific information (the woman added 3 cups of flour) than for general information (the woman added flour). Participants were also slower to detect visual probes presented following F instructions compared to those presented following R instructions. These findings suggest that intentional forgetting is an effortful process that can be performed even on segments of otherwise continuous events and that the result is a relatively impoverished representation of the unwanted information in memory. © 2013 Elsevier B.V.
• Fawcett, J. M., Taylor, T. L., & Nadel, L. (2013). Intentional forgetting diminishes memory for continuous events. Memory, 21(6), 675-694.
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  PMID: 23301998;Abstract: In a novel event method directed forgetting task, instructions to Remember (R) or Forget (F) were integrated throughout the presentation of four videos depicting common events (e.g., baking cookies). Participants responded more accurately to cued recall questions (E1) and true/false statements (E2-4) regarding R segments than F segments. This was true even when forced to attend to F segments by virtue of having to perform concurrent discrimination (E2) or conceptual segmentation (E3) tasks. The final experiment (E5) demonstrated a larger R >F difference for specific true/false statements (the woman added three cups of flour) than for general true/false statements (the woman added flour) suggesting that participants likely encoded and retained at least a general representation of the events they had intended to forget, even though this representation was not as specific as the representation of events they had intended to remember. © 2013 Copyright Taylor and Francis Group, LLC.
• Hardt, O., Nader, K., & Nadel, L. (2013). Decay happens: The role of active forgetting in memory. Trends in Cognitive Sciences, 17(3), 111-120.
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  PMID: 23369831;Abstract: Although the biological bases of forgetting remain obscure, the consensus among cognitive psychologists emphasizes interference processes, rejecting decay in accounting for memory loss. In contrast to this view, recent advances in understanding the neurobiology of long-term memory maintenance lead us to propose that a brain-wide well-regulated decay process, occurring mostly during sleep, systematically removes selected memories. Down-regulation of this decay process can increase the life expectancy of a memory and may eventually prevent its loss. Memory interference usually occurs during certain active processing phases, such as encoding and retrieval, and will be stronger in brain areas with minimal sensory integration and less pattern separation. In areas with efficient pattern separation, such as the hippocampus, interference-driven forgetting will be minimal, and, consequently, decay will cause most forgetting. © 2013 Elsevier Ltd.
• Hoscheidt, S. M., LaBar, K. S., Ryan, L., Jacobs, W. J., & Nadel, L. (2013). Encoding negative events under stress: High subjective arousal is related to accurate emotional memory despite misinformation exposure. Neurobiology of Learning and Memory.
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  Abstract: Stress at encoding affects memory processes, typically enhancing, or preserving, memory for emotional information. These effects have interesting implications for eyewitness accounts, which in real-world contexts typically involve encoding an aversive event under stressful conditions followed by potential exposure to misinformation. The present study investigated memory for a negative event encoded under stress and subsequent misinformation endorsement. Healthy young adults participated in a between-groups design with three experimental sessions conducted 48 h apart. Session one consisted of a psychosocial stress induction (or control task) followed by incidental encoding of a negative slideshow. During session two, participants were asked questions about the slideshow, during which a random subgroup was exposed to misinformation. Memory for the slideshow was tested during the third session. Assessment of memory accuracy across stress and no-stress groups revealed that stress induced just prior to encoding led to significantly better memory for the slideshow overall. The classic misinformation effect was also observed - participants exposed to misinformation were significantly more likely to endorse false information during memory testing. In the stress group, however, memory accuracy and misinformation effects were moderated by arousal experienced during encoding of the negative event. Misinformed-stress group participants who reported that the negative slideshow elicited high arousal during encoding were less likely to endorse misinformation for the most aversive phase of the story. Furthermore, these individuals showed better memory for components of the aversive slideshow phase that had been directly misinformed. Results from the current study provide evidence that stress and high subjective arousal elicited by a negative event act concomitantly during encoding to enhance emotional memory such that the most aversive aspects of the event are well remembered and subsequently more resistant to misinformation effects. © 2013 The Authors.
• Hupbach, A., Gomez, R., & Nadel, L. (2013). Episodic Memory Reconsolidation: An Update. Memory Reconsolidation, 233-247.
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  Abstract: In contrast to the study of memory reconsolidation in animals, research in humans is still in the early stages. This reflects the challenge to directly target memory reconsolidation without the use of pharmacological interventions that are often not safe for humans. Most studies therefore use paradigms in which new material is presented soon after memory reactivation. These studies show that human memories can be modified contingent upon their reactivation. Specifically, the novel material leads to interference in the original memories. This chapter reviews research on episodic memory reconsolidation that uses this approach in an object-learning paradigm. Learning a new set of objects after reactivation of a previous object-set memory causes the new objects to become integrated into the reactivated memory. We present studies that assess different types of reminders and the effects of memory strength and time delays, and we evaluate different theoretical accounts of our findings. © 2013 Elsevier Inc. All rights reserved.
• Nadel, L., & Peterson, M. A. (2013). The hippocampus: Part of an interactive posterior representational system spanning perceptual and memorial systems. Journal of Experimental Psychology: General, 142(4), 1242-1254.
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  PMID: 23895347;Abstract: The hippocampus has frequently been viewed as a core long-term memory structure, separate from brain structures mediating other cognitive functions such as working memory and perception. Much the sameis true of other medial temporal lobe (MTL) structures such as the parahippocampal gyrus and the perirhinal cortex. Recent evidence suggests, instead, that these latter structures are also important for certain perceptual functions, leading many to propose a representational account of MTL that defines its functions in terms of what is being represented, rather than how long this representation lasts, or which psychological function is being invoked. We discuss a common framework within which perception and memory are seen as involving many, if not most, of the structures in the ventral representational stream, critically dependent on extensive feedforward and feedback processes. A variety of perceptual and memorial phenomena are discussed within this framework, and it is concluded that the hippocampus is in many ways like its neighbors in the MTL, yet has some distinct properties that account for its unique role in episodic memory. © 2013 American Psychological Association.
• Nadel, L., Dongaonkar, B., Hupbach, A., Gomez, R., & Nadel, L. -. (2013). Effects of psychosocial stress on episodic memory updating. Psychopharmacology, 226(4).
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  When a consolidated memory is reactivated, it becomes labile and modifiable. Recently, updating of reactivated episodic memory was demonstrated by Hupbach et al. (Learn Mem 14:47-53, 2007). Memory updating involves two vital processes-reactivation followed by reconsolidation. Here, we explored effects of psychosocial stress on episodic memory updating. Based on prior research, we hypothesized that stress before reactivation or stress before reconsolidation would impair memory updating.
• Nadel, L., Hoscheidt, S., & Ryan, L. R. (2013). Spatial cognition and the hippocampus: The anterior-posterior axis. Journal of Cognitive Neuroscience, 25(1), 22-28.
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  PMID: 23198887;Abstract: We discuss the question of differentiation along the anterior- posterior longitudinal axis of the hippocampus. Data from a recent fMRI study are reanalyzed to determine whether activations in these hippocampal regions are affected by the nature of the information being accessed during a scanning session in which participants thought about episodes from their lives. Retrieving detailed spatial relational information preferentially activated the posterior hippocampus, whereas retrieving information about locales (or contexts) preferentially activated the anterior hippocampus. These data support the view that there is functional differentiation along the longitudinal axis in humans that matches what has been seen in rats, namely, that the posterior (dorsal) hippocampus is crucial for precise spatial behavior, and the anterior (ventral) hippocampus is crucial for context coding. © 2012 Massachusetts Institute of Technology.
• Nadel, L., Hupbach, A., Gomez, R., Hardt, O., & Nadel, L. -. (0). Reconsolidation of episodic memories: a subtle reminder triggers integration of new information. Learning & memory (Cold Spring Harbor, N.Y.), 14(1-2).
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  Recent demonstrations of "reconsolidation" suggest that memories can be modified when they are reactivated. Reconsolidation has been observed in human procedural memory and in implicit memory in infants. This study asks whether episodic memory undergoes reconsolidation. College students learned a list of objects on Day 1. On Day 2, they received a reminder or not, and then learned a second list. Memory for List 1 was tested immediately on Day 2 (Experiment 2) or on Day 3 (Experiment 1). Although the reminder did not moderate the number of items recalled from List 1 on either day, subjects who received a reminder incorrectly intermixed items from the second list when recalling List 1 on Day 3. Experiment 2 showed that this effect does not occur immediately and thus is time-dependent. The reminder did not affect memory for List 2 on Day 3 (Experiment 3), demonstrating that modification occurred only for the original memory (List 1). The study demonstrates the crucial role of reminders for the modification of episodic memory, that reconsolidation of episodic memory is time-dependent, and, in contrast to previous reconsolidation findings, that reconsolidation is also a constructive process, one that supports the incorporation of new information in memory.
• Nadel, L., Payne, J. D., & Nadel, L. -. (0). Sleep, dreams, and memory consolidation: the role of the stress hormone cortisol. Learning & memory (Cold Spring Harbor, N.Y.), 11(6).
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  We discuss the relationship between sleep, dreams, and memory, proposing that the content of dreams reflects aspects of memory consolidation taking place during the different stages of sleep. Although we acknowledge the likely involvement of various neuromodulators in these phenomena, we focus on the hormone cortisol, which is known to exert influence on many of the brain systems involved in memory. The concentration of cortisol escalates over the course of the night's sleep, in ways that we propose can help explain the changing nature of dreams across the sleep cycle.
• Poppenk, J., Evensmoen, H. R., Moscovitch, M., & Nadel, L. (2013). Long-axis specialization of the human hippocampus. Trends in Cognitive Sciences, 17(5), 230-240.
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  PMID: 23597720;Abstract: Investigation of the hippocampus has historically focused on computations within the trisynaptic circuit. However, discovery of important anatomical and functional variability along its long axis has inspired recent proposals of long-axis functional specialization in both the animal and human literatures. Here, we review and evaluate these proposals. We suggest that various long-axis specializations arise out of differences between the anterior (aHPC) and posterior hippocampus (pHPC) in large-scale network connectivity, the organization of entorhinal grid cells, and subfield compositions that bias the aHPC and pHPC towards pattern completion and separation, respectively. The latter two differences give rise to a property, reflected in the expression of multiple other functional specializations, of coarse, global representations in anterior hippocampus and fine-grained, local representations in posterior hippocampus. © 2013.
• Fenton, A. A., & Nadel, L. (2012). Obituary - Jan Bureš. Frontiers in Behavioral Neuroscience.
• Jones, B., Bukoski, E., Nadel, L., & Fellous, J. (2012). Remaking memories: Reconsolidation updates positively motivated spatial memory in rats. Learning and Memory, 19(3), 91-98.
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  PMID: 22345494;PMCID: PMC3293515;Abstract: There is strong evidence that reactivation of a memory returns it to a labile state, initiating a restabilization process termed reconsolidation, which allows for updating of the memory. In this study we investigated reactivation-dependent updating using a new positively motivated spatial task in rodents that was designed specifically to model a human list-learning paradigm. On Day 1, rats were trained to run to three feeders (List 1) for rewards. On Day 2, rats were trained to run to three different feeders (List 2) in either the same (Reminder condition) or a different (No Reminder condition) experimental context than on Day 1. On Day 3, rats were cued to recall List 1. Rats in the Reminder condition made significantly more visits to List 2 feeders (intrusions) during List 1 recall than rats in the No Reminder condition, indicating that the reminder triggered reactivation and allowed integration of List 2 items into List 1. This reminder effect was selective for the reactivated List 1 memory, as no intrusions occurred when List 2 was recalled on Day 3. No intrusions occurred when retrieval took place in a different context from the one used at encoding, indicating that the expression of the updated memory is dependent upon the retrieval context. Finally, the level of intrusions was highest when retrieval took place immediately after List 2 learning, and generally declined when retrieval occurred 1-4 h later, indicating that the List 2 memory competed with short-term retrieval of List 1. These results demonstrate the dynamic nature of memory over time and the impact of environmental context at different stages of memory processing. © 2012 Cold Spring Harbor Laboratory Press.
• Nadel, L., Edgin, J. O., Mason, G. M., Spanò, G., Fernández, A., & Nadel, L. -. (2012). Human and mouse model cognitive phenotypes in Down syndrome: implications for assessment. Progress in brain research, 197.
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  The study of cognitive function in Down syndrome (DS) has advanced rapidly in the past decade. Mouse models have generated data regarding the neurological basis for the specific cognitive profile of DS (i.e., deficits in aspects of hippocampal, prefrontal, and cerebellar function) and have uncovered pharmacological treatments with the potential to affect this phenotype. Given this progress, the field is at a juncture in which we require assessments that may effectively translate the findings acquired in mouse models to humans with DS. In this chapter, we describe the cognitive profile of humans with DS and associated mouse models, discussing the ways in which we may merge these findings so as to more fully understand cognitive strengths and weaknesses in this population. New directions for approaches to cognitive assessment in mice and humans are discussed.
• Nadel, L., Hupbach, A., Gomez, R., & Newman-Smith, K. (2012). Memory formation, consolidation and transformation. Neuroscience and Biobehavioral Reviews, 36(7), 1640-1645.
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  PMID: 22465050;Abstract: Memory formation is a highly dynamic process. In this review we discuss traditional views of memory and offer some ideas about the nature of memory formation and transformation. We argue that memory traces are transformed over time in a number of ways, but that understanding these transformations requires careful analysis of the various representations and linkages that result from an experience. These transformations can involve: (1) the selective strengthening of only some, but not all, traces as a function of synaptic rescaling, or some other process that can result in selective survival of some traces; (2) the integration (or assimilation) of new information into existing knowledge stores; (3) the establishment of new linkages within existing knowledge stores; and (4) the up-dating of an existing episodic memory. We relate these ideas to our own work on reconsolidation to provide some grounding to our speculations that we hope will spark some new thinking in an area that is in need of transformation. © 2012 Elsevier Ltd.
• Campbell, J., Nadel, L., Duke, D., & Ryan, L. (2011). Remembering all that and then some: Recollection of autobiographical memories after a 1-year delay. Memory, 19(4), 406-415.
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  PMID: 21678157;PMCID: PMC3773369;Abstract: We have previously shown that repeated retrievals of remote autobiographical memories over the course of one month led to an overall increase in reported detail (Nadel, Campbell, & Ryan, 2007). The current study examined the retrieval of those same memories 1 year later in order to determine whether the level of detail remained stable or whether the memories returned to their original state. Participants reported even more details than they had recalled at least 1 year earlier, including new details that were reported for the first time. This finding was consistent across both multiple and single retrieval conditions, suggesting that the critical factor leading to the increase in recall was the passage of time. These findings provide evidence for long-term effects of repeated retrieval on memory content. © 2011 Psychology Press.
• Hupbach, A., Gomez, R., & Nadel, L. (2011). Episodic memory updating: The role of context familiarity. Psychonomic Bulletin and Review, 18(4), 787-797.
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  PMID: 21647786;Abstract: We previously demonstrated that spatial context is a powerful reminder that can trigger memory updating (Hupbach, Hardt, Gomez, & Nadel in Learning & Memory, 15, 574-579 2008). In the present study, we asked whether the familiarity of the spatial context modulates the role of spatial context as a reminder. Since context familiarity can be easily manipulated in children, we chose 5-year-olds as study participants. In two experiments, we demonstrated robust memory-updating effects in children. Spatial context triggered incorporation of new information into old memories only when the context was unfamiliar. In highly familiar spatial environments (children's homes), spatial context did not initiate memory updating. Other reminders (the experimenter and a reminder question) became highly effective in familiar contexts. These findings shed further light on the specific conditions that trigger memory updating and support the view that the mechanisms underlying it are similar in children and adults. © 2011 Psychonomic Society, Inc.
• Nadel, L., & Hardt, O. (2011). Update on memory systems and processes. Neuropsychopharmacology, 36(1), 251-273.
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  PMID: 20861829;PMCID: PMC3055510;Abstract: Ideas about how the brain organizes learning and memory have been evolving in recent years, with potentially important ramifications. We review traditional thinking about learning and memory and consider more closely emerging trends from both human and animal research that could lead to profound shifts in how we understand the neural basis of memory. © 2011 Nature Publishing Group All rights reserved.
• Hoscheidt, S. M., Nadel, L., Payne, J., & Ryan, L. (2010). Hippocampal activation during retrieval of spatial context from episodic and semantic memory. Behavioural Brain Research, 212(2), 121-132.
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  PMID: 20385169;Abstract: The hippocampus, a region implicated in the processing of spatial information and episodic memory, is central to the debate concerning the relationship between episodic and semantic memory. Studies of medial temporal lobe amnesic patients provide evidence that the hippocampus is critical for the retrieval of episodic but not semantic memory. On the other hand, recent neuroimaging studies of intact individuals report hippocampal activation during retrieval of both autobiographical memories and semantic information that includes historical facts, famous faces, and categorical information, suggesting that episodic and semantic memory may engage the hippocampus during memory retrieval in similar ways. Few studies have matched episodic and semantic tasks for the degree to which they include spatial content, even though spatial content may be what drives hippocampal activation during semantic retrieval. To examine this issue, we conducted a functional magnetic resonance imaging (fMRI) study in which retrieval of spatial and nonspatial information was compared during an episodic and semantic recognition task. Results show that the hippocampus (1) participates preferentially in the retrieval of episodic memories; (2) is also engaged by retrieval of semantic memories, particularly those that include spatial information. These data suggest that sharp dissociations between episodic and semantic memory may be overly simplistic and that the hippocampus plays a role in the retrieval of spatial content whether drawn from a memory of one's own life experiences or real-world semantic knowledge. © 2010.
• Nadel, L. (2010). Shaping the future of cognitive science. Wiley Interdisciplinary Reviews: Cognitive Science, 1(1), 1-.
• Nadel, L., Edgin, J. O., Mason, G. M., Allman, M. J., Capone, G. T., Deleon, I., Maslen, C., Reeves, R. H., Sherman, S. L., & Nadel, L. -. (2010). Development and validation of the Arizona Cognitive Test Battery for Down syndrome. Journal of neurodevelopmental disorders, 2(3).
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  Neurocognitive assessment in individuals with intellectual disabilities requires a well-validated test battery. To meet this need, the Arizona Cognitive Test Battery (ACTB) has been developed specifically to assess the cognitive phenotype in Down syndrome (DS). The ACTB includes neuropsychological assessments chosen to 1) assess a range of skills, 2) be non-verbal so as to not confound the neuropsychological assessment with language demands, 3) have distributional properties appropriate for research studies to identify genetic modifiers of variation, 4) show sensitivity to within and between sample differences, 5) have specific correlates with brain function, and 6) be applicable to a wide age range and across contexts. The ACTB includes tests of general cognitive ability and prefrontal, hippocampal and cerebellar function. These tasks were drawn from the Cambridge Neuropsychological Testing Automated Battery (CANTAB) and other established paradigms. Alongside the cognitive testing battery we administered benchmark and parent-report assessments of cognition and behavior. Individuals with DS (n=74, ages 7-38 years) and mental age (MA) matched controls (n=50, ages 3-8 years) were tested across 3 sites. A subsample of these groups were used for between-group comparisons, including 55 individuals with DS and 36 mental age matched controls. The ACTB allows for low floor performance levels and participant loss. Floor effects were greater in younger children. Individuals with DS were impaired on a number ACTB tests in comparison to a MA-matched sample, with some areas of spared ability, particularly on tests requiring extensive motor coordination. Battery measures correlated with parent report of behavior and development. The ACTB provided consistent results across contexts, including home vs. lab visits, cross-site, and among individuals with a wide range of socio-economic backgrounds and differences in ethnicity. The ACTB will be useful in a range of outcome studies, including clinical trials and the identification of important genetic components of cognitive disability.
• Nadel, L., Ryan, L., Lin, C., Ketcham, K., & Nadel, L. -. (2010). The role of medial temporal lobe in retrieving spatial and nonspatial relations from episodic and semantic memory. Hippocampus, 20(1).
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  This study examined the involvement of medial temporal lobe, especially the hippocampus, in processing spatial and nonspatial relations using episodic and semantic versions of a relational judgment task. Participants studied object arrays and were tested on different types of relations between pairs of objects. Three prevalent views of hippocampal function were considered. Cognitive map theory (O'Keefe and Nadel (1978) The Hippocampus as a Cognitive Map. USA: Oxford University Press) emphasizes hippocampal involvement in spatial relational tasks. Multiple trace theory (Nadel and Moscovitch (1997) Memory consolidation, retrograde amnesia and the hippocampal complex Curr Opin Neurobiol 7:217-227) emphasizes hippocampal involvement in episodic tasks. Eichenbaum and Cohen's ((2001) From Conditioning to Conscious Recollection: Memory Systems of the Brain. USA: Oxford University Press) relational theory predicts equivalent hippocampal involvement in all relational tasks within both semantic and episodic memory. The fMRI results provided partial support for all three theories, though none of them fit the data perfectly. We observed hippocampal activation during all relational tasks, with increased activation for spatial compared to nonspatial relations, and for episodic compared to semantic relations. The placement of activation along the anterior-posterior axis of the hippocampus also differentiated the conditions. We suggest a view of hippocampal function in memory that incorporates aspects of all three theories.
• Ryan, L., Ryan, L., Lin, C., Lin, C., Ketcham, K., Ketcham, K., Nadel, L., & Nadel, L. (2010). The role of medial temporal lobe in retrieving spatial and nonspatial relations from episodic and semantic memory. Hippocampus, 20(1), 11-18.
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  PMID: 19405148;Abstract: This study examined the involvement of medial temporal lobe, especially the hippocampus, in processing spatial and nonspatial relations using episodic and semantic versions of a relational judgment task. Participants studied object arrays and were tested on different types of relations between pairs of objects. Three prevalent views of hippocampal function were considered. Cognitive map theory (O'Keefe and Nadel (1978) The Hippocampus as a Cognitive Map. USA: Oxford University Press) emphasizes hippocampal involvement in spatial relational tasks. Multiple trace theory (Nadel and Moscovitch (1997) Memory consolidation, retrograde amnesia and the hippocampal complex Curr Opin Neurobiol 7:217-227) emphasizes hippocampal involvement in episodic tasks. Eichenbaum and Cohen's ((2001) From Conditioning to Conscious Recollection: Memory Systems of the Brain. USA: Oxford University Press) relational theory predicts equivalent hippocampal involvement in all relational tasks within both semantic and episodic memory. The fMRI results provided partial support for all three theories, though none of them fit the data perfectly. We observed hippocampal activation during all relational tasks, with increased activation for spatial compared to nonspatial relations, and for episodic compared to semantic relations. The placement of activation along the anterior-posterior axis of the hippocampus also differentiated the conditions. We suggest a view of hippocampal function in memory that incorporates aspects of all three theories. © 2009 Wiley-Liss, Inc.
• Thomas, K. G., Laurance, H. E., Nadel, L., & Jacobs, W. J. (2010). Stress-induced impairment of spatial navigation in females. South African Journal of Psychology, 40(1), 32-43.
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  Abstract: Earlier work predicted that the physiological effects of an acute stressor disrupt a neurological system underlying cognitive-map (CM) guided navigation, but leave intact systems underlying landmark (LM) guided navigation. This prediction has been only partially confirmed. Furthermore, no-one has investigated sex differences in the relations between acute stress and spatial navigation, even though stress affects verbal memory and decision-making performance of males and females differently. We administered the Trier Social Stress Test (TSST), a standardized laboratory procedure designed to induce mild psychosocial stress, to 15 healthy undergraduates to examine the effects of acute stress on CM- and LM-guided navigation in men and women. They, and a demographically matched control group of 14 undergraduates, completed a virtual environment navigation task. Exposure to the TSST disrupted CM-guided (but not LM-guided) navigation in women, but affected neither in men. The data partially support the previous work, and offer novel findings regarding the relative vulnerability to acute psychosocial stress of CM-based navigation in females. © Psychological Society of South Africa. All rights reserved.
• Hardt, O., & Nadel, L. (2009). Cognitive maps and attention. Progress in Brain Research, 176, 181-194.
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  PMID: 19733757;Abstract: Cognitive map theory suggested that exploring an environment and attending to a stimulus should lead to its integration into an allocentric environmental representation. We here report that directed attention in the form of exploration serves to gather information needed to determine an optimal spatial strategy, given task demands and characteristics of the environment. Attended environmental features may integrate into spatial representations if they meet the requirements of the optimal spatial strategy: when learning involves a cognitive mapping strategy, cues with high codability (e.g., concrete objects) will be incorporated into a map, but cues with low codability (e.g., abstract paintings) will not. However, instructions encouraging map learning can lead to the incorporation of cues with low codability. On the other hand, if spatial learning is not map-based, abstract cues can and will be used to encode locations. Since exploration appears to determine what strategy to apply and whether or not to encode a cue, recognition memory for environmental features is independent of whether or not a cue is part of a spatial representation. In fact, when abstract cues were used in a way that was not map-based, or when they were not used for spatial navigation at all, they were nevertheless recognized as familiar. Thus, the relation between exploratory activity on the one hand and spatial strategy and memory on the other appears more complex than initially suggested by cognitive map theory. © 2009 Elsevier B.V. All rights reserved.
• Hardt, O., Hupbach, A., & Nadel, L. (2009). Factors moderating blocking in human place learning: The role of task instructions. Learning and Behavior, 37(1), 42-59.
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  PMID: 19122052;Abstract: Cognitive map theory assumes that novel environmental information is automatically incorporated into existing cognitive maps as a function of exploration. Reports of blocking in place learning cast doubt on this claim. In these studies, subjects were first trained to find a place, using a set of landmarks (Set A). Then novel landmarks (Set B) were added for additional trials. Subsequent removal of the Set A landmarks showed that the novel landmarks alone were insufficient for successful navigation. We investigated whether instructing human subjects to explore the environment can moderate blocking. First, we demonstrated that blocking is absent in a computer implementation of the Morris water maze (MWM) in which subjects are instructed to explore. We then studied why others found blocking in a different MWM implementation, in which the task instructions did not suggest exploration. In experiments that faithfully replicated this MWM variant, we found that subjects did not acquire cognitive maps and that blocking was attenuated when instructions were provided that encouraged exploration. Together, these findings indicate that blocking in human place learning may reflect a performance deficit, not a learning deficit, and that instructions can moderate blocking. Our results thus support the automatic update assumption of cognitive map theory. © 2009 The Psychonomic Society, Inc.
• Hupbach, A., Gomez, R. L., Bootzin, R. R., & Nadel, L. (2009). Nap-dependent learning in infants. Developmental Science, 12(6), 1007-1012.
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  PMID: 19840054;Abstract: Sleep has been shown to aid a variety of learning and memory processes in adults (Stickgold, 2005). Recently, we showed that infants' learning also benefits from subsequent sleep such that infants who nap are able to abstract the general grammatical pattern of a briefly presented artificial language (Gomez, Bootzin & Nadel, 2006). In the present study, we demonstrate, for the first time, long-term effects of sleep on memory for an artificial language. Fifteen-month-old infants who had napped within 4 hours of language exposure remembered the general grammatical pattern of the language 24 hours later. In contrast, infants who had not napped shortly after being familiarized with the language showed no evidence of remembering anything about the language. Our findings support the view that infants' frequent napping plays an essential role in establishing long-term memory. © 2009 Blackwell Publishing Ltd.
• Hupbach, A., Gomez, R., & Nadel, L. (2009). Episodic memory reconsolidation: Updating or source confusion?. Memory, 17(5), 502-510.
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  PMID: 19468955;Abstract: Reactivation of apparently stable, long-term memory can render it fragile, and dependent on a re-stabilisation process referred to as "reconsolidation". Recently we provided the first demonstration of reconsolidation effects in human episodic memory (Hupbach, Gomez, Hardt, & Nadel, 2007; Hupbach, Hardt, Gomez, & Nadel, 2008). Memory for a set of objects was modified by the presentation of a new set, if and only if participants were reminded of the first learning episode before learning the new set. The present study asks whether this effect can be interpreted as a source discrimination problem; i.e., participants have difficulties remembering which objects were presented during which session, and do not actually incorporate new objects into the reactivated memory. The present study used a recognition test and asked participants directly about the source of their memories. Participants in the no-reminder group showed very few source errors. Participants in the reminder group misattributed the source of objects from the second set as being from the first set but not vice versa, thus demonstrating updating of the original memory. This finding is informative with respect to the misinformation paradigm, and reconsolidation is discussed as a possible mechanism underlying our results and the misinformation effect.
• Moskowitz, A., Nadel, L., Watts, P., & Jacobs, W. J. (2009). Delusional Atmosphere, The Psychotic Prodrome and Decontextualized Memories. Psychosis, Trauma and Dissociation: Emerging Perspectives on Severe Psychopathology, 65-78.
• Nadel, L., Hupbach, A., Gomez, R. L., Bootzin, R. R., & Nadel, L. -. (2009). Nap-dependent learning in infants. Developmental science, 12(6).
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  Sleep has been shown to aid a variety of learning and memory processes in adults (Stickgold, 2005). Recently, we showed that infants' learning also benefits from subsequent sleep such that infants who nap are able to abstract the general grammatical pattern of a briefly presented artificial language (Gomez, Bootzin & Nadel, 2006). In the present study, we demonstrate, for the first time, long-term effects of sleep on memory for an artificial language. Fifteen-month-old infants who had napped within 4 hours of language exposure remembered the general grammatical pattern of the language 24 hours later. In contrast, infants who had not napped shortly after being familiarized with the language showed no evidence of remembering anything about the language. Our findings support the view that infants' frequent napping plays an essential role in establishing long-term memory.
• Nadel, L., Hupbach, A., Gomez, R., & Nadel, L. -. (2009). Episodic memory reconsolidation: updating or source confusion?. Memory (Hove, England), 17(5).
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  Reactivation of apparently stable, long-term memory can render it fragile, and dependent on a re-stabilisation process referred to as "reconsolidation". Recently we provided the first demonstration of reconsolidation effects in human episodic memory (Hupbach, Gomez, Hardt, & Nadel, 2007; Hupbach, Hardt, Gomez, & Nadel, 2008). Memory for a set of objects was modified by the presentation of a new set, if and only if participants were reminded of the first learning episode before learning the new set. The present study asks whether this effect can be interpreted as a source discrimination problem; i.e., participants have difficulties remembering which objects were presented during which session, and do not actually incorporate new objects into the reactivated memory. The present study used a recognition test and asked participants directly about the source of their memories. Participants in the no-reminder group showed very few source errors. Participants in the reminder group misattributed the source of objects from the second set as being from the first set but not vice versa, thus demonstrating updating of the original memory. This finding is informative with respect to the misinformation paradigm, and reconsolidation is discussed as a possible mechanism underlying our results and the misinformation effect.
• Dere, E., Easton, A., Nadel, L., & Huston, J. P. (2008). Preface. Handbook of Behavioral Neuroscience, 18, ix-x.
• Eaton, D. L., Daroff, R. B., Autrup, H., Bridges, J., Buffler, P., Costa, L. G., Coyle, J., McKhann, G., Mobley, W. C., Nadel, L., Neubert, D., Schulte-Hermann, R., & Spencer, P. S. (2008). Review of the toxicology of chlorpyrifos with an emphasis on human exposure and neurodevelopment. Critical Reviews in Toxicology, 38(SUPPL.2), 1-125.
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  PMID: 18726789;Abstract: This review examines the large body of toxicological and epidemiological information on human exposures to chlorpyrifos, with an emphasis on the controversial potential for chlorpyrifos to induce neurodevelopmental effects at low doses. The results of this review demonstrate that the use of urinary 3,5,6-trichlorpyridinol (TCPy), a metabolite of chlorpyrifos as a biomarker of nonoccupational exposure is problematic and may overestimate nonoccupational exposures to chlorpyrifos by 10-to 20-fold because of the widespread presence of both TCPy and chlorpyrifos-methyl in the food supply. Current "background" (nonoccupational) levels of exposure to chlorpyrifos are several orders of magnitude lower than those required to inhibit plasma cholinesterase activity, which is a more sensitive target than nervous system cholinesterase. However, several in vitro studies have identified putative neurodevelopmental mechanisms that are altered at concentrations of chlorpyrifos below those that inhibit cholinesterases. Although one human cohort study reported an association between maternal and cord blood chlorpyrifos levels and several measures of neurodevelopment, two other cohort studies that utilized urinary TCPy as a surrogate for chlorpyrifos exposure did not demonstrate an association. Although the weight of the scientific evidence demonstrates that current levels of chlorpyrifos exposure will not have any adverse effects on neurodevelopment that might result from inhibition of nervous system cholinesterases, several recent studies propose alternative mechanisms. Thus, further in vivo investigation on neurodevelopment in an appropriate animal model is needed; additional epidemiological studies may be warranted if a suitable, chlorpyrifos-exposed cohort can be identified and more rigorous measures of exposure are utilized. Copyright © 2008 Informa UK Ltd.
• Ellmore, T. M., Stouffer, K., & Nadel, L. (2008). Divergence of explicit and implicit processing speed during associative memory retrieval. Brain Research, 1229, 155-166.
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  PMID: 18655778;PMCID: PMC2566546;Abstract: Consolidation theory assumes that as time passes, some memories are strengthened and become resistant to change while other memories are weakened and forgotten. Recent demonstrations that implicit, or procedural, memories are retrieved more efficiently after learning and retention are consistent with the idea that these particular memory traces have strengthened with time, and therefore may be accessed faster. However, it is not clear whether the process of explicit memory retrieval also becomes more efficient with time. In two experiments, we explored 1) how much time is required for retrieval of separate explicit and implicit components of hippocampal-dependent visuomotor associative memories after variable retention intervals, and 2) how the explicit and implicit processing times change when the associations are rehearsed after initial retrieval. We found that after learning and retention, explicit and implicit processing times diverged: 1) the time taken to retrieve successfully the explicit component increased relative to a pre-retention baseline but, after spaced rehearsal, decreased, although not to a level significantly below that obtained at the end of learning, and 2) the implicit, or procedural, component processing times continued to gradually decrease after retention, and with continued rehearsal, reached a level significantly below the pre-retention baseline. We conclude that the observed divergence in post-retention reaction times suggests that explicit and implicit memory systems may reorganize differently after learning, and that as a consequence, different amounts of processing time may be required for retrieval of these different memory components. © 2008 Elsevier B.V. All rights reserved.
• Hupbach, A., Hardt, O., Gomez, R., & Nadel, L. (2008). The dynamics of memory: Context-dependent updating. Learning and Memory, 15(8), 574-579.
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  PMID: 18685148;Abstract: Understanding the dynamics of memory change is one of the current challenges facing cognitive neuroscience. Recent animal work on memory reconsolidation shows that memories can be altered long after acquisition. When reactivated, memories can be modified and require a restabilization (reconsolidation) process. We recently extended this finding to human episodic memory by showing that memory reactivation mediates the incorporation of new information into existing memory. Here we show that the spatial context plays a unique role for this type of memory updating: Being in the same spatial context during original and new learning is both necessary and sufficient for the incorporation of new information into existing episodic memories. Memories are automatically reactivated when subjects return to an original learning context, where updating by incorporating new contents can occur. However, when in a novel context, updating of existing memories does not occur, and a new episodic memory is created instead. © 2008 Cold Spring Harbor Laboratory Press.
• Moscovitch, M., Winocur, G., Ryan, L., & Nadel, L. (2008). Chapter 3.1 Functional neuroanatomy of remote, episodic memory. Handbook of Behavioral Neuroscience, 18, 239-269.
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  Abstract: We examine theories of remote episodic memory with special emphasis on functional neuroanatomy. The chapter highlights the debate between proponents of the standard consolidation model, which considers the hippocampus as a temporary memory structure needed only until memories are consolidated elsewhere, and proponents of multiple trace theory (MTT) who hold that the hippocampus always is needed to retain and recover detailed episodic memories. The theories are evaluated on evidence from behavioral, lesion, and functional neuroimaging studies in humans and other organisms, and in light of theories of anterograde memory function. The contribution of other neocortical structures to remote episodic memory is also reviewed in regard to these theories. Though the evidence is inconclusive with respect to some issues, we conclude that on balance it favors MTT. In the final sections of the chapter, we consider new directions in which the field is moving, with special emphasis on the relation between remote memory and other functions such as sematic memory, planning for the future, problem solving, theory of mind, and imagination. © 2008 Elsevier B.V. All rights reserved.
• Nadel, L., Ellmore, T. M., Stouffer, K., & Nadel, L. -. (2008). Divergence of explicit and implicit processing speed during associative memory retrieval. Brain research, 1229.
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  Consolidation theory assumes that as time passes, some memories are strengthened and become resistant to change while other memories are weakened and forgotten. Recent demonstrations that implicit, or procedural, memories are retrieved more efficiently after learning and retention are consistent with the idea that these particular memory traces have strengthened with time, and therefore may be accessed faster. However, it is not clear whether the process of explicit memory retrieval also becomes more efficient with time. In two experiments, we explored 1) how much time is required for retrieval of separate explicit and implicit components of hippocampal-dependent visuomotor associative memories after variable retention intervals, and 2) how the explicit and implicit processing times change when the associations are rehearsed after initial retrieval. We found that after learning and retention, explicit and implicit processing times diverged: 1) the time taken to retrieve successfully the explicit component increased relative to a pre-retention baseline but, after spaced rehearsal, decreased, although not to a level significantly below that obtained at the end of learning, and 2) the implicit, or procedural, component processing times continued to gradually decrease after retention, and with continued rehearsal, reached a level significantly below the pre-retention baseline. We conclude that the observed divergence in post-retention reaction times suggests that explicit and implicit memory systems may reorganize differently after learning, and that as a consequence, different amounts of processing time may be required for retrieval of these different memory components.
• Nadel, L., Hupbach, A., Hardt, O., & Gomez, R. (2008). Chapter 1.4 Episodic memory: reconsolidation. Handbook of Behavioral Neuroscience, 18, 43-56.
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  Abstract: In contrast to the accepted wisdom that memories become fixed over time, recent evidence has renewed interest in the dynamic quality of memory, suggesting that even old memories are subject to revision and reconsolidation given the right circumstances. We discuss a new paradigm developed to study reconsolidation of episodic memory in humans, showing that reminders can open a previously established memory to updating based on new experience. We show that under laboratory conditions the experimental context plays a critical role in determining whether or not such memory updating will occur; but that under conditions where the context is highly familiar other factors might play this role. The nature of context is explored, linking our results to work on hippocampus, and the results of a neuroimaging study exploring the impact of reactivation of well-established memory are described. Our results, situated within a broader context, set the stage for future explorations of the cognitive neuroscience of the malleability of memory. © 2008 Elsevier B.V. All rights reserved.
• Nadel, L., Hupbach, A., Hardt, O., Gomez, R., & Nadel, L. -. (2008). The dynamics of memory: context-dependent updating. Learning & memory (Cold Spring Harbor, N.Y.), 15(8).
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  Understanding the dynamics of memory change is one of the current challenges facing cognitive neuroscience. Recent animal work on memory reconsolidation shows that memories can be altered long after acquisition. When reactivated, memories can be modified and require a restabilization (reconsolidation) process. We recently extended this finding to human episodic memory by showing that memory reactivation mediates the incorporation of new information into existing memory. Here we show that the spatial context plays a unique role for this type of memory updating: Being in the same spatial context during original and new learning is both necessary and sufficient for the incorporation of new information into existing episodic memories. Memories are automatically reactivated when subjects return to an original learning context, where updating by incorporating new contents can occur. However, when in a novel context, updating of existing memories does not occur, and a new episodic memory is created instead.
• Nadel, L., Ryan, L., Cox, C., Hayes, S. M., & Nadel, L. -. (2008). Hippocampal activation during episodic and semantic memory retrieval: comparing category production and category cued recall. Neuropsychologia, 46(8).
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  Whether or not the hippocampus participates in semantic memory retrieval has been the focus of much debate in the literature. However, few neuroimaging studies have directly compared hippocampal activation during semantic and episodic retrieval tasks that are well matched in all respects other than the source of the retrieved information. In Experiment 1, we compared hippocampal fMRI activation during a classic semantic memory task, category production, and an episodic version of the same task, category cued recall. Left hippocampal activation was observed in both episodic and semantic conditions, although other regions of the brain clearly distinguished the two tasks. Interestingly, participants reported using retrieval strategies during the semantic retrieval task that relied on autobiographical and spatial information; for example, visualizing themselves in their kitchen while producing items for the category kitchen utensils. In Experiment 2, we considered whether the use of these spatial and autobiographical retrieval strategies could have accounted for the hippocampal activation observed in Experiment 1. Categories were presented that elicited one of three retrieval strategy types, autobiographical and spatial, autobiographical and nonspatial, and neither autobiographical nor spatial. Once again, similar hippocampal activation was observed for all three category types, regardless of the inclusion of spatial or autobiographical content. We conclude that the distinction between semantic and episodic memory is more complex than classic memory models suggest.
• Ryan, L., Cox, C., Hayes, S. M., & Nadel, L. (2008). Hippocampal activation during episodic and semantic memory retrieval: Comparing category production and category cued recall. Neuropsychologia, 46(8), 2109-2121.
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  PMID: 18420234;PMCID: PMC2482601;Abstract: Whether or not the hippocampus participates in semantic memory retrieval has been the focus of much debate in the literature. However, few neuroimaging studies have directly compared hippocampal activation during semantic and episodic retrieval tasks that are well matched in all respects other than the source of the retrieved information. In Experiment 1, we compared hippocampal fMRI activation during a classic semantic memory task, category production, and an episodic version of the same task, category cued recall. Left hippocampal activation was observed in both episodic and semantic conditions, although other regions of the brain clearly distinguished the two tasks. Interestingly, participants reported using retrieval strategies during the semantic retrieval task that relied on autobiographical and spatial information; for example, visualizing themselves in their kitchen while producing items for the category kitchen utensils. In Experiment 2, we considered whether the use of these spatial and autobiographical retrieval strategies could have accounted for the hippocampal activation observed in Experiment 1. Categories were presented that elicited one of three retrieval strategy types, autobiographical and spatial, autobiographical and nonspatial, and neither autobiographical nor spatial. Once again, similar hippocampal activation was observed for all three category types, regardless of the inclusion of spatial or autobiographical content. We conclude that the distinction between semantic and episodic memory is more complex than classic memory models suggest. © 2008 Elsevier Ltd. All rights reserved.
• Ryan, L., Hoscheidt, S., & Nadel, L. (2008). Chapter 1.1 Perspectives on episodic and semantic memory retrieval. Handbook of Behavioral Neuroscience, 18, 5-18,616.
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  Abstract: Episodic or autobiographical recollection involves re-experiencing a past event that is specific in time and place, while semantic recollection is concerned with facts and general knowledge about the world. Several prominent memory theories posit that the hippocampus differentiates between these two types of memories, mediating episodic, but not semantic, retrieval. In this chapter we explore a different view of hippocampus, one that emphasizes a singular response of the hippocampus during memory encoding and retrieval of both episodic and semantic memories, based on an amalgam of two existing theories of hippocampal function, multiple trace theory (MTT; Nadel & Moscovitch, 1997), and cognitive map theory (O'Keefe & Nadel, 1978). We review neuropsychological and neuroimaging literature suggesting that both semantic and episodic memory retrieval engages the hippocampus, at least within the normally functioning brain. We then describe an updated version of MTT that incorporates these new findings. Finally, we explore the notion that differences in the role the hippocampus plays in these forms of memory reflect two critical factors - the nature of the information being retrieved, and the requirements of the retrieval task. © 2008 Elsevier B.V. All rights reserved.
• Fidler, D. J., & Nadel, L. (2007). Education and children with down syndrome: Neuroscience, development, and intervention. Mental Retardation and Developmental Disabilities Research Reviews, 13(3), 262-271.
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  PMID: 17910079;Abstract: Of the recent advances in education-related research in Down syndrome, the characterization of the Down syndrome behavioral phenotype has become a potentially critical tool for shaping education and intervention in this population. This article briefly reviews the literature on brain-behavior connections in Down syndrome and identifies aspects of the Down syndrome behavioral phenotype that are potentially relevant to educators. Potential challenges to etiologically informed educational planning are discussed. © 2007 Wiley-Liss, Inc.
• Hayes, S. M., Hayes, S. M., Nadel, L., Nadel, L., Ryan, L., & Ryan, L. (2007). The effect of scene context on episodic object recognition: Parahippocampal cortex mediates memory encoding and retrieval success. Hippocampus, 17(9), 873-889.
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  PMID: 17604348;PMCID: PMC3615418;Abstract: Previous research has investigated intentional retrieval of contextual information and contextual influences on object identification and word recognition, yet few studies have investigated context effects in episodic memory for objects. To address this issue, unique objects embedded in a visually rich scene or on a white background were presented to participants. At test, objects were presented either in the original scene or on a white background. A series of behavioral studies with young adults demonstrated a context shift decrement (CSD) - decreased recognition performance when context is changed between encoding and retrieval. The CSD was not attenuated by encoding or retrieval manipulations, suggesting that binding of object and context may be automatic. A final experiment explored the neural correlates of the CSD, using functional Magnetic Resonance Imaging. Parahippocampal cortex (PHC) activation (right greater than left) during incidental encoding was associated with subsequent memory of objects in the context shift condition. Greater activity in right PHC was also observed during successful recognition of objects previously presented in a scene. Finally, a subset of regions activated during scene encoding, such as bilateral PHC, was reactivated when the object was presented on a white background at retrieval. Although participants were not required to intentionally retrieve contextual information, the results suggest that PHC may reinstate visual context to mediate successful episodic memory retrieval. The CSD is attributed to automatic and obligatory binding of object and context. The results suggest that PHC is important not only for processing of scene information, but also plays a role in successful episodic memory encoding and retrieval. These findings are consistent with the view that spatial information is stored in the hippocampal complex, one of the central tenets of Multiple Trace Theory. © 2007 Wiley-Liss, Inc.
• Hupbach, A., Gomez, R., Hardt, O., & Nadel, L. (2007). Reconsolidation of episodic memories: A subtle reminder triggers integration of new information. Learning and Memory, 14(1), 47-53.
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  PMID: 17202429;PMCID: PMC1838545;Abstract: Recent demonstrations of "reconsolidation" suggest that memories can be modified when they are reactivated. Reconsolidation has been observed in human procedural memory and in implicit memory in infants. This study asks whether episodic memory undergoes reconsolidation. College students learned a list of objects on Day 1. On Day 2, they received a reminder or not, and then learned a second list. Memory for List 1 was tested immediately on Day 2 (Experiment 2) or on Day 3 (Experiment 1). Although the reminder did not moderate the number of items recalled from List 1 on either day, subjects who received a reminder incorrectly intermixed items from the second list when recalling List 1 on Day 3. Experiment 2 showed that this effect does not occur immediately and thus is time-dependent. The reminder did not affect memory for List 2 on Day 3 (Experiment 3), demonstrating that modification occurred only for the original memory (List 1). The study demonstrates the crucial role of reminders for the modification of episodic memory, that reconsolidation of episodic memory is time-dependent, and, in contrast to previous reconsolidation findings, that reconsolidation is also a constructive process, one that supports the incorporation of new information in memory. ©2007 by Cold Spring Harbor Laboratory Press.
• Hupbach, A., Hardt, O., Nadel, L., & Bohbot, V. D. (2007). Spatial reorientation: Effects of verbal and spatial shadowing. Spatial Cognition and Computation, 7(2), 213-226.
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  Abstract: Spatially disoriented adults flexibly conjoin geometric information (macroscopic shape) and nongeometric information (e.g., the color of a wall) to re-establish their bearings. It has been proposed that non-geometric information is incorporated into a geometric frame of reference through the use of spatial language. Support for this assumption comes from dual-task studies in which participants failed to use non-geometric features when they shadowed a verbal message concurrent to the reorientation task. These studies were performed in small rectangular spaces. In contrast, our study was performed in a large square room. Experiment 1 showed that verbal shadowing did not disrupt non-geometric feature use in this environment. In Experiment 2, we found that a spatial shadowing task that required the encoding of frequently changing spatial directions impaired reorientation behavior. Our study shows that nongeometric information can be used for reorientation without recourse to linguistic processes, and suggests that the use of non-geometric features is dependent upon a spatial coding process. © 2007, Lawrence Erlbaum Associates, Inc.
• Kallai, J., Karádi, K., Bereczkei, T., Rózsa, S., Jacobs, W. J., & Nadel, L. (2007). Spatial exploration behaviour in an extended labyrinth in patients with panic disorder and agoraphobia. Psychiatry Research, 149(1-3), 223-230.
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  PMID: 17150259;Abstract: Finding one's way through a labyrinth is both stressful and panicogenic for individuals suffering from panic disorder with agoraphobia (PDA), whilst normal subjects experience no stress. In this study the spatial exploratory behaviour of 15 subjects suffering from PDA, together with 15 patients with generalised anxiety disorder (GAD) and a further 15 normal control subjects - all female - was analysed during a walk through a labyrinth-like basement in an attempt to find the exit. The study covered behavioural variables, i.e., anxiety levels whilst route-searching and exploration-related movements (the frequency and intensity of trunk and head rotation, touching oneself and folding one's arms across the chest) and also physiological variables (blood pressure, heart rate) before and after the labyrinth walk. Data obtained in the PDA subjects were compared with those of the GAD and control subjects, and it was found that the PDA subjects' high blood pressure was associated with disturbed exploratory activity, which restricted their contact to the environment. As a consequence, they did not detect navigation signals to find the right route to the labyrinth exit. The interpretation focused on the analysis of the structure of human extraterritorial fear. © 2006 Elsevier Ltd. All rights reserved.
• Kallai, J., Makany, T., Csatho, A., Karadi, K., Horvath, D., Kovacs-Labadi, B., Jarai, R., Nadel, L., & Jacobs, J. W. (2007). Cognitive and affective aspects of thigmotaxis strategy in humans. Behavioral Neuroscience, 121(1), 21-30.
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  PMID: 17324048;Abstract: The present article describes the cognitive and emotional aspects of human thigmotaxis (a wall-following spatial strategy) during exploration of virtual and physical spaces. The authors assessed 106 participants with spatial and nonspatial performance-based learning-memory tasks and with fear and anxiety questionnaires. The results demonstrate that thigmotaxis plays a distinct role at different phases of spatial learning. The 1st phase shows a positive correlation between thigmotaxis and general phobic avoidance, whereas there is no association between thigmotaxis and general phobic avoidance during later phases of learning. Furthermore, participants who underperformed in working memory tests and in a spatial construction task exhibited greater thigmotaxis and a higher potential for fear response. Findings are interpreted in the framework of interactions among emotion-, action-, and knowledge-controlled spatial learning theories. © 2007 APA, all rights reserved.
• Nadel, L. -., Hayes, S. M., Ryan, ., & L., . (2007). The Effect of Scene Context on Episodic Object Recognition: Parahippocampal Cortex Mediates Memory Encoding and Retrieval Success. Hippocampus.
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  ;Your Role: Helped design experiments and write paper.;Full Citation: Hayes, S. M., Nadel, L. and Ryan, L. The Effect of Scene Context on Episodic Object Recognition: Parahippocampal Cortex Mediates Memory Encoding and Retrieval Success, Hippocampus, 17, 873-889, 2007.;Collaborative with graduate student: Yes;Collaborative with faculty member in unit: Yes;
• Nadel, L. -., Hupbach, A., Bohbot, V., & Hardt, O. (2007). Spatial reorientation: Effects of verbal and spatial shadowing.. Journal of Spatial Cognition and Computation.
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  ;Your Role: Helped write paper.;Full Citation: Hupbach, A., Bohbot, V., Hardt, O. and Nadel, L. Spatial reorientation: Effects of verbal and spatial shadowing. Journal of Spatial Cognition and Computation, 7, 213-226, 2007.;Other collaborative: Yes;Specify other collaborative: Collaborative with postdocs at UA and colleague at McGill.;
• Nadel, L. -., Hupbach, A., Gomez, R., & Hardt, O. (2007). Reconsolidation of episodic memories: A subtle reminder triggers integration of new information. Learning and Memory.
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  ;Your Role: Helped design experiments and write paper.;Full Citation: Hupbach, A., Gomez, R., Nadel, L. & Hardt, O. Reconsolidation of episodic memories: A subtle reminder triggers integration of new information Learning and Memory, 14, 47-53, 2007.;Collaborative with faculty member in unit: Yes;Other collaborative: Yes;Specify other collaborative: Collaborative with post-docs.;
• Nadel, L. -., Kallai, J., Karádi, K., Bereczkei, T., RĂłzsa, S., & Jacobs, W. J. (2007). Spatial exploration behaviour in an extended labyrinth in patients with panic disorder with agoraphobia.. Psychiatry Research.
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  ;Your Role: Helped write the paper.;Full Citation: Kallai, J., Karádi, K., Bereczkei, T., Rózsa, S., Jacobs, W. J. & Nadel, L. Spatial exploration behaviour in an extended labyrinth in patients with panic disorder with agoraphobia. Psychiatry Research, 149, 223-230, 2007.;Collaborative with faculty member in unit: Yes;Other collaborative: Yes;Specify other collaborative: Collaborative with colleague at UA and group in Hungary.;
• Nadel, L. -., Kallai, J., Makány, T., CsathĂł, A., Karádi, K., Horváth, D., Kovacs-Labadi, B., Jarai, R., & Jacobs, W. J. (2007). Cognitive and affective aspects of thigmotaxis strategy in humans.. Behavioral Neuroscience.
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  ;Your Role: Helped write paper;Full Citation: Kallai, J., Makány, T., Csathó, A., Karádi, K., Horváth, D., Kovacs-Labadi, B., Jarai, R., Nadel, L. and Jacobs, W.J. Cognitive and affective aspects of thigmotaxis strategy in humans. Behavioral Neuroscience, 121, 21-30, 2007.;Collaborative with faculty member in unit: Yes;Other collaborative: Yes;Specify other collaborative: Collaborative with colleague at UA and group in Hungary.;
• Nadel, L. -., Payne, J. D., Jackson, E., Hoscheidt, S., Ryan, L., & Jacobs, W. J. (2007). Stress Impairs Neutral but Enhances Emotional Episodic Memories. Learning and Memory.
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  ;Your Role: Helped design experiments and write paper.;Full Citation: Payne, J.D., Jackson, E., Hoscheidt, S., Ryan, L., Jacobs, W.J. and Nadel, L. Stress Impairs Neutral but Enhances Emotional Episodic Memories, Learning and Memory, 14, 861-868, 2007.;Collaborative with graduate student: Yes;Collaborative with faculty member in unit: Yes;
• Nadel, L. -., Winocur, G., Ryan, L., Moscovitch, ., & M, . (2007). Systems Consolidation and Hippocampus: Two Views.. Debates in Neuroscience.
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  ;Your Role: Wrote first draft and oversaw final version.;Full Citation: Nadel, L., Winocur, G., Ryan, L. and Moscovitch, M. Systems Consolidation and Hippocampus: Two Views. Debates in Neuroscience, online. 2007.;Collaborative with faculty member in unit: Yes;Other collaborative: Yes;Specify other collaborative: Collaborative with colleague at UA and others at Toronto.;
• Nadel, L., Campbell, J., & Ryan, L. (2007). Autobiographical memory retrieval and hippocampal activation as a function of repetition and the passage of time. Neural Plasticity, 2007.
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  PMID: 18274617;PMCID: PMC2233815;Abstract: Multiple trace theory (MTT) predicts that hippocampal memory traces expand and strengthen as a function of repeated memory retrievals. We tested this hypothesis utilizing fMRI, comparing the effect of memory retrieval versus the mere passage of time on hippocampal activation. While undergoing fMRI scanning, participants retrieved remote autobiographical memories that had been previously retrieved either one month earlier, two days earlier, or multiple times during the preceding month. Behavioral analyses revealed that the number and consistency of memory details retrieved increased with multiple retrievals but not with the passage of time. While all three retrieval conditions activated a similar set of brain regions normally associated with autobiographical memory retrieval including medial temporal lobe structures, hippocampal activation did not change as a function of either multiple retrievals or the passage of time. However, activation in other brain regions, including the precuneus, lateral prefrontal cortex, parietal cortex, lateral temporal lobe, and perirhinal cortex increased after multiple retrievals, but was not influenced by the passage of time. These results have important implications for existing theories of long-term memory consolidation.
• Nadel, L., Winocur, G., Ryan, L., & Moscovitch, M. (2007). Systems consolidation and hippocampus: Two views. Debates in Neuroscience, 1(2-4), 55-66.
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  Abstract: Two approaches to systems-level memory consolidation are contrasted. The standard model and multiple trace theory are spelled out, their implications are outlined, and their fit to the data from a number of approaches is evaluated. We conclude that the data from neuroimaging studies strongly support multiple trace theory, that data from neuropsychological studies favor but does not conclusively support multiple trace theory, while evidence from a new approach, the study of prospective memory, also supporting multiple trace theory, offers a promising new way to distinguish between these two theories. Work with animals is largely consistent with this conclusion. We suggest that the hippocampal and neocortical systems are critical for different forms of memory, and that the shift of memory from dependence on hippocampus to dependence on neocortex during consolidation is a reflection of the fact that memory often is transformed with time, becoming more generic in nature. Insofar as detailed episodic recollections are retained, the data show that they are dependent on the hippocampal system, much as multiple trace theory postulated. © Springer Verlag 2007.
• Payne, J. D., Jackson, E. D., Hoscheidt, S., Ryan, L., Jacobs, W. J., & Nadel, L. (2007). Stress administered prior to encoding impairs neutral but enhances emotional long-term episodic memories. Learning and Memory, 14(12), 861-868.
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  PMID: 18086830;PMCID: PMC2151024;Abstract: Stressful events frequently comprise both neutral and emotionally arousing information, yet the impact of stress on emotional and neutral events is still not fully understood. The hippocampus and frontal cortex have dense concentrations of receptors for stress hormones, such as cortisol, which at high levels can impair performance on hippocampally dependent memory tasks. Yet, the same stress hormones can facilitate memory for emotional information, which involves interactions between the hippocampus and amygdala. Here, we induced psychosocial stress prior to encoding and examined its long-term effects on memory for emotional and neutral episodes. The stress manipulation disrupted long-term memory for a neutral episode, but facilitated long-term memory for an equivalent emotional episode compared with a control condition. The stress manipulation also increased salivary cortisol, catecholamines as indicated by the presence of α-amylase, heart rate, and subjectively reported stress. Stressed subjects reported more false memories than nonstressed control subjects, and these false memories correlated positively with cortisol levels, providing evidence for a relationship between stress and false memory formation. Our results demonstrate that stress, when administered prior to encoding, produces different patterns of long-term remembering for neutral and emotional episodes. These differences likely emerge from differential actions of stress hormones on memory-relevant regions of the brain. © 2007 Cold Spring Harbor Laboratory Press.
• Gómez, R. L., Bootzin, R. R., & Nadel, L. (2006). Naps promote abstraction in language-learning infants. Psychological Science, 17(8), 670-674.
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  PMID: 16913948;Abstract: Infants engage in an extraordinary amount of learning during their waking hours even though much of their day is consumed by sleep. What role does sleep play in infant learning? Fifteen-month-olds were familiarized with an artificial language 4 hr prior to a lab visit. Learning the language involved relating initial and final words in auditory strings by remembering the exact word dependencies or by remembering an abstract relation between initial and final words. One group napped during the interval between familiarization and test. Another group did not nap. Infants who napped appeared to remember a more abstract relation, one they could apply to stimuli that were similar but not identical to those from familiarization. Infants who did not nap showed a memory effect. Naps appear to promote a qualitative change in memory, one involving greater flexibility in learning. Copyright © 2006 Association for Psychological Science.
• Jackson, E. D., Payne, J. D., Nadel, L., & Jacobs, W. J. (2006). Stress differentially modulates fear conditioning in healthy men and women. Biological Psychiatry, 59(6), 516-522.
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  PMID: 16213468;Abstract: Background: Stress and stress hormones modulate emotional learning in rats and might have similar effects in humans. Theoretic accounts of posttraumatic stress disorder (PTSD), for example, implicate the stress-induced modulation of fear conditioning in the development of intrusive emotional reactions. The present study examined the impact of acute stress and cortisol (CORT) on classically conditioned fear in men and women. Methods: Ninety-four healthy undergraduates were exposed to a mild stressor (or control condition) while subjective anxiety and glucocorticoid stress responses (salivary CORT) were measured. One hour later, all participants participated in a differential fear conditioning procedure while conditioned skin conductance responses (SCR) were recorded. Results: Exposure to the stressor increased subjective anxiety and elevated CORT levels. In men, stress exposure facilitated fear conditioning; whereas in women, stress appeared to inhibit fear conditioning. The impact of stress on differential conditioning in men was associated with increased CORT levels. Conclusions: Consistent with animal models, these results demonstrate that stress exposure can modulate classical conditioning in humans, possibly via hormonal mechanisms. The enhancing effects of stress on the formation of conditioned fear might provide a useful model for the formation of pathological emotional reactions, such as those found in PTSD. © 2005 Society of Biological Psychiatry.
• Moscovitch, M., Nadel, L., Winocur, G., Gilboa, A., & Rosenbaum, R. S. (2006). The cognitive neuroscience of remote episodic, semantic and spatial memory. Current Opinion in Neurobiology, 16(2), 179-190.
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  PMID: 16564688;Abstract: The processes and mechanisms implicated in retention and retrieval of memories as they age is an enduring problem in cognitive neuroscience. Research from lesion and functional neuroimaging studies on remote episodic, semantic and spatial memory in humans is crucial for evaluating three theories of hippocampal and/or medial temporal lobe-neocortical interaction in memory retention and retrieval: cognitive map theory, standard consolidation theory and multiple trace theory. Each theory makes different predictions regarding first, the severity and extent of retrograde amnesia following lesions to some or all of the structures mentioned; second, the extent of activation of these structures to retrieval of memory across time; and third, the type of memory being retrieved. Each of these theories has strengths and weaknesses, and there are various unresolved issues. We propose a unified account based on multiple trace theory. This theory states that the hippocampus is needed for re-experiencing detailed episodic and spatial memories no matter how old they are, and that it contributes to the formation and assimilation of semantic memories and schematic spatial maps. © 2006 Elsevier Ltd. All rights reserved.
• Nadel, L. (2006). Preface. Cognitive Systems - Information Processing Meets Brain Science, ix-x.
• Nadel, L. -. (2006). The cognitive neuroscience of remote episodic, semantic and spatial memory.. Current Opinion in Neurobiology.
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  ;Your Role: Developing the theory and helping to write the paper.;Full Citation: Moscovitch, M., Nadel, L., Winocur, G., Gilboa, A. and Rosenbaum, S. The cognitive neuroscience of remote episodic, semantic and spatial memory. Current Opinion in Neurobiology, 16, 179-190, 2006.;Other collaborative: Yes;Specify other collaborative: Review article written with colleagues at Toronto, with whom I have developed the theory under discussion.;
• Nadel, L. -., Gomez, R. L., & Bootzin, R. R. (2006). Naps promote language learning in infants. Psychological Science.
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  ;Your Role: Originated idea, co-wrote the paper.;Full Citation: Gomez, R.L., Bootzin, R.R. and Nadel, L. Naps promote language learning in infants, Psychological Science, 17, 670-674, 2006.;Collaborative with faculty member in unit: Yes;
• Nadel, L. -., Jackson, E. D., Payne, J. D., & Jacobs, W. J. (2006). Stress differentially modulates fear conditioning in healthy men and women. Biological Psychiatry.
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  ;Your Role: Helped design study and write up paper.;Full Citation: Jackson, E.D., Payne, J.D., Nadel, L. and Jacobs, W.J. Stress differentially modulates fear conditioning in healthy men and women Biological Psychiatry, 59, 516-522, 2006.;Collaborative with graduate student: Yes;Collaborative with faculty member in unit: Yes;
• Nadel, L. -., Payne, J. D., Jackson, E. D., Ryan, L., Hoscheidt, S., & Jacobs, W. J. (2006). The Impact of Stress on Neutral and Emotional Aspects of Episodic Memory.. Memory.
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  ;Your Role: Helped design study and write up paper.;Full Citation: Payne, J.D., Jackson, E.D., Ryan, L., Hoscheidt, S., Jacobs, W.J. and Nadel, L. The Impact of Stress on Neutral and Emotional Aspects of Episodic Memory. Memory, 1, 1-16, 2006.;Collaborative with undergraduate student: Yes;Collaborative with graduate student: Yes;Collaborative with faculty member in unit: Yes;
• Nadel, L., Gómez, R. L., Bootzin, R. R., & Nadel, L. -. (2006). Naps promote abstraction in language-learning infants. Psychological science, 17(8).
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  Infants engage in an extraordinary amount of learning during their waking hours even though much of their day is consumed by sleep. What role does sleep play in infant learning? Fifteen-month-olds were familiarized with an artificial language 4 hr prior to a lab visit. Learning the language involved relating initial and final words in auditory strings by remembering the exact word dependencies or by remembering an abstract relation between initial and final words. One group napped during the interval between familiarization and test. Another group did not nap. Infants who napped appeared to remember a more abstract relation, one they could apply to stimuli that were similar but not identical to those from familiarization. Infants who did not nap showed a memory effect. Naps appear to promote a qualitative change in memory, one involving greater flexibility in learning.
• Nadel, L., Payne, J. D., Jackson, E. D., Ryan, L., Hoscheidt, S., Jacobs, J. W., & Nadel, L. -. (2006). The impact of stress on neutral and emotional aspects of episodic memory. Memory (Hove, England), 14(1).
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  The present experiment demonstrates that exposure to a significant psychological stressor (administered before watching a slide show) preserves or even enhances memory for emotional aspects of an event, and simultaneously disrupts memory for non-emotional aspects of the same event. Stress exposure also disrupted memory for information that was visually and thematically central to the event depicted in the slide show. Memory for peripheral information, on the other hand, was unaffected by stress. These results are consistent with theories invoking differential effects of stress on brain systems responsible for encoding and retrieving emotional memories (the amygdala) and non-emotional memories (e.g., the hippocampal formation), and inconsistent with the view that memories formed under high levels of stress are qualitatively the same as those formed under ordinary emotional circumstances. These data, which are also consistent with results obtained in a number of studies using animals and humans, have implications for the traumatic memory debate and theories regarding human memory.
• Payne, J. D., Jackson, E. D., Ryan, L., Hoscheidt, S., Jacobs, W. J., & Nadel, L. (2006). The impact of stress on neutral and emotional aspects of episodic memory. Memory, 14(1), 1-16.
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  PMID: 16423737;Abstract: The present experiment demonstrates that exposure to a significant psychological stressor (administered before watching a slide show) preserves or even enhances memory for emotional aspects of an event, and simultaneously disrupts memory for non-emotional aspects of the same event. Stress exposure also disrupted memory for information that was visually and thematically central to the event depicted in the slide show. Memory for peripheral information, on the other hand, was unaffected by stress. These results are consistent with theories invoking differential effects of stress on brain systems responsible for encoding and retrieving emotional memories (the amygdala) and non-emotional memories (e.g., the hippocampal formation), and inconsistent with the view that memories formed under high levels of stress are qualitatively the same as those formed under ordinary emotional circumstances. These data, which are also consistent with results obtained in a number of studies using animals and humans, have implications for the traumatic memory debate and theories regarding human memory. © 2006 Psychology Press Ltd.
• Hupbach, A., & Nadel, L. (2005). Reorientation in a rhombic environment: No evidence for an encapsulated geometric module. Cognitive Development, 20(2), 279-302.
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  Abstract: Reorientation behavior of young children has been described as dependent upon a geometric module that is incapable of interacting with landmark information. Whereas previous studies typically used rectangular spaces that provided geometric information about distance, we used a rhombic space that allowed us to explore the way children use geometric information about angles. Reorientation was studied in manipulatory space (Experiment 1) and locomotor space (Experiment 2) in the presence and absence of a salient landmark. In the absence of salient landmarks, 4- to 6-year-olds used geometric features to reorient in both spaces. When a salient landmark was available in manipulatory space, 4-year-olds used the landmark and ignored the geometry. Five- and 6-year-olds used the geometry, but in combination with the landmark. In locomotor space, this combined use was already seen at age 4, and increased with age. Taken together, these results offer no support for the notion that reorientation behavior in young children depends on an informationally encapsulated geometric module. © 2005 Elsevier Inc. All rights reserved.
• Kallai, J., Csathó, Á., Kövér, F., Makány, T., Nemes, J., Horváth, K., Kovács, N., Manning, J. T., Nadel, L., & Nagy, F. (2005). MRI-assessed volume of left and right hippocampi in females correlates with the relative length of the second and fourth fingers (the 2D:4D ratio). Psychiatry Research - Neuroimaging, 140(2), 199-210.
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  PMID: 16257514;Abstract: Atrophy of the left or right side of the hippocampus has been related to cognitive deficits and psychiatric disease. In this study, we examined the correlation between the hippocampal volume laterality index and the relative lengths of the second (index finger) and fourth (ring finger) digits (2D:4D) in healthy female subjects. The 2D:4D ratio is fixed in utero, and the ratio is higher in women than in men. There is evidence that this ratio is an indicator of the intrauterine concentration of testosterone, which influences the development of different regions of the brain. Assessing the volume of different parts of the brain of 40 healthy adult female students by magnetic resonance imaging (MRI), we found that the 2D:4D ratio was associated with an asymmetry in the hippocampal sub-regions. Smaller volume on the left side was found in the posterior part of the hippocampus in females with a low (masculine type) 2D:4D ratio. On the other hand, smaller volume on the left side was found in the middle part of the hippocampus in females with a high (female type) 2D:4D ratio. Thus, the development of the middle and posterior regions of the hippocampal formation may respond in opposite ways to prenatal levels of testosterone. Other brain regions such as the amygdala, the cerebral cortex, the total volume hippocampus, and the head of the hippocampus did not show such a difference. © 2005 Elsevier Ireland Ltd. All rights reserved.
• Lane, R. D., & Nadel, L. (2005). Ongoing discussion: Douglas F. Watt's book review of lane & nadel, cognitive neuroscience of emotion. Neuropsychoanalysis, 7(1), 103-105.
• Moscovitch, M., Rosenbaum, R. S., Gilboa, A., Addis, D. R., Westmacott, R., Grady, C., McAndrews, M. P., Levine, B., Black, S., Winocur, G., & Nadel, L. (2005). Functional neuroanatomy of remote episodic, semantic and spatial memory: A unified account based on multiple trace theory. Journal of Anatomy, 207(1), 35-66.
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  PMID: 16011544;PMCID: PMC1571502;Abstract: We review lesion and neuroimaging evidence on the role of the hippocampus, and other structures, in retention and retrieval of recent and remote memories. We examine episodic, semantic and spatial memory, and show that important distinctions exist among different types of these memories and the structures that mediate them. We argue that retention and retrieval of detailed, vivid autobiographical memories depend on the hippocampal system no matter how long ago they were acquired. Semantic memories, on the other hand, benefit from hippocampal contribution for some time before they can be retrieved independently of the hippocampus. Even semantic memories, however, can have episodic elements associated with them that continue to depend on the hippocampus. Likewise, we distinguish between experientially detailed spatial memories (akin to episodic memory) and more schematic memories (akin to semantic memory) that are sufficient for navigation but not for re-experiencing the environment in which they were acquired. Like their episodic and semantic counterparts, the former type of spatial memory is dependent on the hippocampus no matter how long ago it was acquired, whereas the latter can survive independently of the hippocampus and is represented in extra-hippocampal structures. In short, the evidence reviewed suggests strongly that the function of the hippocampus (and possibly that of related limbic structures) is to help encode, retain, and retrieve experiences, no matter how long ago the events comprising the experience occurred, and no matter whether the memories are episodic or spatial. We conclude that the evidence favours a multiple trace theory (MTT) of memory over two other models: (1) traditional consolidation models which posit that the hippocampus is a time-limited memory structure for all forms of memory; and (2) versions of cognitive map theory which posit that the hippocampus is needed for representing all forms of allocentric space in memory. © Anatomical Society of Great Britain and Ireland 2005.
• Moscovitch, M., Westmacott, R., Gilboa, A., Addis, D. R., Rosenbaum, R. S., Viskontas, I., Priselac, S., Svoboda, E., Ziegler, M., Black, S., Gao, F., Grady, C., Freedman, M., Köhler, S., Leach, L., Levine, B., McAndrews, M. P., Nadel, L., Proulx, G., , Richards, B., et al. (2005). Hippocampal complex contribution to retention and retrieval of recent and remote episodic and semantic memories: Evidence from behavioral and neuroimaging studies of healthy and brain-damaged people. Dynamic Cognitive Processes, 333-380.
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  Abstract: For over a hundred years, it has been accepted that remote memories are less vulnerable to disruption than are recent memories. The standard consolidation model posits that the hippocampus and related structures are temporary memory structures, necessary for acquisition, retention, and retrieval of all explicit (declarative) memories until they are consolidated elsewhere in the brain. We review lesion and neuroimaging evidence showing that important distinctions exist among different types of explicit memory and the structures that mediate them. We argue that retention and retrieval of detailed, vivid autobiographical memories depend on the hippocampal system no matter how long ago they were acquired. Semantic memories, on the other hand, benefit from hippocampal contribution for some time before they can be retrieved independently of the hippocampus. Even semantic memories, however, can have episodic elements associated with them which continue to depend on the hippocampus. In short, the evidence reviewed suggests strongly that the function of the hippocampus (and possibly of related limbic structures) is to help encode, retain, and retrieve experiences, no matter how long ago the events comprising the experience occurred. We conclude that the evidence favors a multiple trace theory (MTT) of memory over the traditional model, and we indicate what future work is needed to resolve disputes. © 2005 Springer-Verlag Tokyo.
• Nadel, L. -., & Hupbach, A. (2005). Reorientation in a rhombic-shaped environment: No evidence for an encapsulated geometric module.. Cognitive Development.
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  ;Your Role: Co-developed of the empirical study and co-author of the paper.;Full Citation: Hupbach, A. and Nadel, L. Reorientation in a rhombic-shaped environment: No evidence for an encapsulated geometric module. Cognitive Development, 20, 279-302, 2005;Other collaborative: Yes;Specify other collaborative: Collaborative with post-doc.;
• Nadel, L. -., & Samsonovich, A. (2005). Fundamental principles and mechanisms of the conscious self. Cortex.
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  ;Your Role: Co-author and co-developer of the theoretical views in this paper.;Full Citation: Samsonovich, A. & Nadel, L. Fundamental principles and mechanisms of the conscious self. Cortex, 41, 669-689, 2005.;Other collaborative: Yes;Specify other collaborative: Collaborative with a post-doc;
• Nadel, L. -., Kallai, J., Nagy, ., Nemes, ., Manning, ., T., J., & Nagy, . (2005). MRI-assessed volume of left and right hippocampi in females correlates with the relative length of the second and fourth fingers (the 2D:4D ratio).. Psychiatry Research: Neuroimaging.
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  ;Your Role: Helped with ideas and writing of paper.;Full Citation: Kallai J, Csathó, Nagy, F., Kövér, F., Makány, T., Nemes, J., Horváth, K., Kovács, N., Manning, J. T., Nadel L. & Nagy, F. MRI-assessed volume of left and right hippocampi in females correlates with the relative length of the second and fourth fingers (the 2D:4D ratio). Psychiatry Research: Neuroimaging 140: 199-210, 2005.;Other collaborative: Yes;Specify other collaborative: Empirical paper based on work in Hungary done as part of a funded collaboration with Dr. Kallai's group there.;
• Nadel, L. -., Moscovitch, M., Rosenbaum, S., Gilboa, A., Addis, D., Westmacott, R., Grady, C., McAndrews, M. P., & Winocur, G. (2005). Functional neuroanatomy of remote episodic (autobiographical), semantic and spatial memory in humans as determined by lesion and functional neuroimaging studies: A unified account based on Multiple Trace Theory. Journal of Anatomy.
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  ;Your Role: Co-author of the theory being reviewed, and on of many who contributed to the drafting of the paper.;Full Citation: Moscovitch, M., Rosenbaum, S., Gilboa, A., Addis, D., Westmacott, R., Grady, C., McAndrews, M.P., Winocur, G. and Nadel, L. Functional neuroanatomy of remote episodic (autobiographical), semantic and spatial memory in humans as determined by lesion and functional neuroimaging studies: A unified account based on Multiple Trace Theory, Journal of Anatomy, 207, 35-66, 2005.;Other collaborative: Yes;Specify other collaborative: A review paper covering work testing a theory of which I was co-originator in 1997.;
• Nadel, L. -., Payne, J. D., Britton, W., & Bootzin, R. (2005). Beyond Acetylcholine: Next Steps for Sleep and Memory Research.. Brain and Behavioral Sciences.
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  ;Your Role: Contributed to writing.;Full Citation: Payne, J.D., Britton, W., Bootzin, R. and Nadel, L. Beyond Acetylcholine: Next Steps for Sleep and Memory Research. Brain and Behavioral Sciences, 28, 77, 2005.;Collaborative with graduate student: Yes;Collaborative with faculty member in unit: Yes;
• Payne, J. D., Britton, W. B., Bootzin, R. R., & Nadel, L. (2005). Beyond acetylcholine: Next steps for sleep and memory research. Behavioral and Brain Sciences, 28(1), 77-.
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  Abstract: We consider Walker's thorough review in the context of thinking about future research on the relation between sleep and memory. We first address methodological issues including type of memory and sleep-stage dependency. We suggest a broader investigation of potential signaling molecules that may be critical to sleep-related consolidation. A brief review of the importance of the stress hormone cortisol illustrates this point.
• Samsonovich, A. V., & Nadel, L. (2005). Fundamental principles and mechanisms of the conscious self. Cortex, 41(5), 669-689.
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  PMID: 16209330;Abstract: We start by assuming that the self is implemented in the brain as a functional unit, with a definite set of properties. We deduce the fundamental properties of the self from an analysis of neurological disorders and from introspection. We formulate a functionalist concept of the self based on these properties reduced to constraints. We use the formalism of schemas in our functionalist analysis, i.e. a symbolic level description of brain dynamics. We then reformulate the functionalist model at a connectionist level and address the emergent "context shifting" problem. We suggest how the model might be mapped onto the functional neuroanatomy of the brain, and how it could be used to give an account of a range of neurological disorders, including hippocampal amnesia, various forms of schizophrenia, multiple personality, autism, PTSD, hemineglect, and reversible anosognosia. Finally, we briefly discuss future perspectives and possible applications of computer implementations of the model.
• Hayes, S. M., Ryan, L., Schnyer, D. M., & Nadel, L. (2004). An fMRI study of episodic memory: Retrieval of object, spatial, and temporal information. Behavioral Neuroscience, 118(5), 885-896.
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  PMID: 15506871;PMCID: PMC3172698;Abstract: Sixteen participants viewed a videotaped tour of 4 houses that highlighted a series of objects and their spatial locations. Participants were tested for memory of object, spatial, and temporal-order information while undergoing functional magnetic resonance imaging. Preferential activation was observed in the right parahippocampal gyrus during the retrieval of spatial-location information. Retrieval of contextual information (spatial location and temporal order) was associated with activation in the right dorsolateral prefrontal cortex. In bilateral posterior parietal regions, greater activation was associated with processing of visual scenes regardless of the memory judgment. These findings support current theories positing roles for frontal and medial temporal regions during episodic retrieval and suggest a specific role for the hippocampal complex in the retrieval of spatial-location information.
• Nadel, L., & Hardt, O. (2004). The spatial brain. Neuropsychology, 18(3), 473-476.
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  PMID: 15291725;Abstract: Themes emerging from the collection of articles in the Special Section on Long-Term Spatial Memory include the notion of multiple spatial systems, the relation between spatial representations and episodic memory, the role of context, and the neural systems involved in space. The authors conclude that distinguishing between egocentric and allocentric spatial systems makes sense of both behavioral and neurobiological data. The special role of the hippocampal system in allocentric space, and as a consequence, in context, suggests how a spatial system might end up central to the ability to remember episodes.
• Nadel, L., Hayes, S. M., Ryan, L., Schnyer, D. M., & Nadel, L. -. (2004). An fMRI study of episodic memory: retrieval of object, spatial, and temporal information. Behavioral neuroscience, 118(5).
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  Sixteen participants viewed a videotaped tour of 4 houses that highlighted a series of objects and their spatial locations. Participants were tested for memory of object, spatial, and temporal-order information while undergoing functional magnetic resonance imaging. Preferential activation was observed in the right parahippocampal gyrus during the retrieval of spatial-location information. Retrieval of contextual information (spatial location and temporal order) was associated with activation in the right dorsolateral prefrontal cortex. In bilateral posterior parietal regions, greater activation was associated with processing of visual scenes regardless of the memory judgment. These findings support current theories positing roles for frontal and medial temporal regions during episodic retrieval and suggest a specific role for the hippocampal complex in the retrieval of spatial-location information.
• Payne, J. D., & Nadel, L. (2004). Sleep, dreams, and memory consolidation: The role of the stress hormone cortisol. Learning and Memory, 11(6), 671-678.
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  PMID: 15576884;PMCID: PMC534695;Abstract: We discuss the relationship between sleep, dreams, and memory, proposing that the content of dreams reflects aspects of memory consolidation taking place during the different stages of sleep. Although we acknowledge the likely involvement of various neuromodulators in these phenomena, we focus on the hormone cortisol, which is known to exert influence on many of the brain systems involved in memory. The concentration of cortisol escalates over the course of the night's sleep, in ways that we propose can help explain the changing nature of dreams across the sleep cycle.
• Laurance, H. E., Learmonth, A. E., Nadel, L., & Jacobs, W. J. (2003). Maturation of spatial navigation strategies: Convergent findings from computerized spatial environments and self-report. Journal of Cognition and Development, 4(2), 211-238.
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  Abstract: Using 2 computerized spatial navigation tasks, we examined the development of cue and place learning in children ages 3 to 10 years, comparing their data to adults. We also examined relations between place learning in computerized and real space. Results showed children use the 2-dimensional space as if it were real space. Results also demonstrated that children ages 3 to 10 years cue learn (locating a visible target) but do not show evidence of mature place learning (locating an invisible target) until around age 10 years. Self-report data indicated an age-related increase in use of relations among distal cues during place learning. Children ages 3 to 4 years did not report using distal cues; most 9- to 10-year-old children reported using multiple distal cues to guide their search during place learning. Results suggest that, as maturation proceeds, children make increasing use of relations among multiple distal cues to guide a search for places in space. Copyright © 2003, Lawrence Erlbaum Associates.
• Nadel, L. (2003). Down's syndrome: A genetic disorder in biobehavioral perspective. Genes, Brain and Behavior, 2(3), 156-166.
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  PMID: 12931789;Abstract: Down's syndrome is a genetic disorder that can lead to mental retardation of varying degrees. How this chromosomal abnormality causes mental retardation remains an open question. This paper reviews what is currently known about the neural and cognitive features of Down's syndrome, noting the growing evidence of disproportionate impairment of specific systems such as the hippocampal formation, the prefrontal cortex and the cerebellum. The development of animal models of these defects offers a way of ultimately connecting the genetic disorder to its cognitive consequences.
• Pennington, B. F., Moon, J., Edgin, J., Stedron, J., Nadel, L., Pennington, B. F., Moon, J., Edgin, J., Stedron, J., & Nadel, L. (2003). The Neuropsychology of Down Syndrome: Evidence for Hippocampal Dysfunction. Child Development, 74(1), 75-93.
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  PMID: 12625437;Abstract: This study tested prefrontal and hippocampal functions in a sample of 28 school-aged (M = 14.7 years, SD = 2.7) individuals with Down syndrome (DS) compared with 28 (M = 4.9 years, SD = .75) typically developing children individually matched on mental age (MA). Both neuropsychological domains were tested with multiple behavioral measures. Benchmark measures of verbal and spatial function demonstrated that this DS sample was similar to others in the literature. The main finding was a significant Group × Domain interaction effect indicating differential hippocampal dysfunction in the group with DS. However, there was a moderate partial correlation (r = .54, controlling for chronological age) between hippocampal and prefrontal composite scores in the DS group, and both composites contributed unique variance to the prediction of MA and adaptive behavior in that group. In sum, these results indicate a particular weakness in hippocampal functions in DS in the context of overall cognitive dysfunction. It is interesting that these results are similar to what has been found in a mouse model of DS. Such a model will make it easier to understand the neurobiological mechanisms that lead to the development of hippocampal dysfunction in DS.
• Bohbot, V. D., Jech, R., Růžička, E., Nadel, L., Kalina, M., Stěpánková, K., & Bureš, J. (2002). Rat spatial memory tasks adapted for humans: Characterization in subjects with intact brain and subjects with medial temporal lobe lesions. Physiological Research, 51(SUPPL. 1), S49-S65.
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  PMID: 12479786;Abstract: In the present paper we describe five tests, 3 of which were designed to be similar to tasks used with rodents. Results obtained from control subjects, patients with selective thermo-coagulation lesions to the medial temporal lobe and results from non-human primates and rodents are discussed. The tests involve memory for spatial locations acquired by moving around in a room, memory for objects subjects interacted with, or memory for objects and their locations. Two of the spatial memory tasks were designed specifically as analogs of the Morris water task and the 8-arm radial-maze tasks used with rats. The Morris water task was modeled by hiding a sensor under the carpet of a room (Invisible Sensor Task). Subjects had to learn its location by using an array of visual cues available in the room. A path integration task was developed in order to study the non-visual acquisition of a cognitive representation of the spatial location of objects. In the non-visual spatial memory task, we blindfolded subjects and led them to a room where they had to find 3 objects and remember their locations. We designed an object location task by placing 4 objects in a room that subjects observed for later recall of their locations. A recognition task, and a novelty detection task were given subsequent to the recall task. An 8-arm radial-maze was recreated by placing stands at equal distance from each other around the room, and asking subjects to visit each stand once, from a central point. A non-spatial working memory task was designed to be the non-spatial equivalent of the radial maze. Search paths recorded on the first trial of the Invisible Sensor Task, when subjects search for the target by trial and error are reported. An analysis of the search paths revealed that patients with lesions to the right or left hippocampus or parahippocampal cortex employed the same type of search strategies as normal controls did, showing similarities and differences to the search behavior recorded in rats. Interestingly, patients with lesions that included the right parahippocampal cortex were impaired relative to patients with lesions to the right hippocampus that spared the parahippocampal cortex, when recall of the sensor was tested after a 30 min delay (Bohbot et al. 1998). No differences were obtained between control subjects and patients with selective thermal lesions to the medial temporal lobe, when tested on the radial-maze, the non-spatial analogue to the radial-maze and the path integration tasks. Differences in methodological procedures, learning strategies and lesion location could account for some of the discrepant results between humans and non-human species. Patients with lesions to the right hippocampus, irrespective of whether the right parahippocampal cortex was spared or damaged, had difficulties remembering the particular configuration and identity of objects in the novelty detection of the object location task. This supports the role of the human right hippocampus for spatial memory, in this case, involving memory for the location of elements in the room; learning known to require the hippocampus in the rat.
• Learmonth, A. E., Nadel, L., & Newcombe, N. S. (2002). Children's use of landmarks: Implications for modularity theory. Psychological Science, 13(4), 337-341.
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  PMID: 12137136;Abstract: Previous studies have shown that disoriented children use the geometric features of the environment to reorient, but the results have not consistently demonstrated whether children can combine such information with landmark information. Results indicating that they cannot suggest the existence of a geometric module for reorientation. However, results indicating that children can use geometric information in combination with landmark information challenge the modularity interpretation. An uncontrolled variable in the studies yielding conflicting results has been the size of the experimental space. In the present studies, which tested young children in spaces of two different sizes, the size of the space affected their ability to use available landmark information. In the small space, the children did not use the landmark to reorient, but in the large space they did. The ability of children to use landmarks in combination with geometric information raises important questions about the existence of an encapsulated geometric module. Copyright © 2002 American Psychological Society.
• Makány, T., Karádi, K., Kállai, J., & Nadel, L. (2002). Interference between verbal concept formation and spatial mental rotation in female subjects. Perceptual and Motor Skills, 95(1), 227-232.
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  PMID: 12365259;Abstract: In this study the relation between spatial cognition and verbal intelligence abilities was examined in case of 52 women. Interference between mental rotation performance and verbal intelligence scores was found. Women with good verbal abilities have lower scores in mental rotation tasks than subjects with poorer verbal abilities. This finding is in accordance with some basic models of a dual-coding system. The spatial functions represented in mental rotation interfered with verbal-based concept formation and lexical knowledge in college women.
• Nadel, L., Payne, J. D., & Jacobs, W. J. (2002). The relationship between episodic memory and context: Clues from memory errors made while under stress. Physiological Research, 51(SUPPL. 1), S3-S11.
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  PMID: 12479781;
• Payne, J. D., Nadel, L., Allen, J. J., Thomas, K. G., & Jacobs, W. J. (2002). The effects of experimentally induced stress on false recognition. Memory, 10(1), 1-6.
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  PMID: 11747571;Abstract: The fallibility of memory has become an issue of considerable practical and theoretical importance. Here we studied the impact of experimentally induced stress on the ability of human participants to accurately recognise words presented on a list. We found that stress selectively disrupted participants' ability to distinguish words that were presented for study from critical lure words that were semantically related, but not presented for study. This finding indicates that stress, possibly through its impact on the hippocampus and prefrontal cortex, can potentiate false memories.
• G., K., Hsu, M., Laurance, H. E., Nadel, L., & Jacobs, W. J. (2001). Place learning in virtual space III: Investigation of spatial navigation training procedures and their application to fMRI and clinical neuropsychology. Behavior Research Methods, Instruments, and Computers, 33(1), 21-37.
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  PMID: 11296717;Abstract: This paper describes the utilization of a desktop virtual environment task, the Computer-Generated (C-G) Arena, in the study of human spatial navigation. First, four experiments examined the efficacy of various training procedures in the C-G Arena. In Experiment 1, participants efficiently located a hidden target after only observing the virtual environment from a fixed position (placement learning). In Experiment 2, participants efficiently located a hidden target after only observing an experimenter search the virtual environment (observational learning). In Experiment 3, participants failed to display a latent learning effect in the virtual environment. In Experiment 4, all training procedures effectively taught participants the layout of the virtual environment, but the observational learning procedure most effectively taught participants the location of a hidden target within the environment. Finally, two experiments demonstrated the application of C-G Arena procedures to neuroimaging (Experiment 5) and neuropsychological (Experiment 6) investigations of human spatial navigation.
• Nadel, L., & Bohbot, V. (2001). Consolidation of memory. Hippocampus, 11(1), 56-60.
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  PMID: 11261773;Abstract: Animal studies have proven useful in addressing aspects of memory formation and consolidation that cannot be readily answered in research with humans. In particular, they offer the possibility of controlling both the extent and locus of brain lesions, and the exact nature of the experiences to be remembered. Taking advantage of these possibilities, recent studies indicated that the graded retrograde amnesia often seen after lesions to the hippocampal system is not uniform across lesions site and task, nor is it an indication that all of the remembered information available in intact subjects becomes available after hippocampal system lesions made a long time after learning. Rather, these studies support the notion that information is stored in both hippocampal and extrahippocampal sites, and that retrieval from different sites involves access to different kinds of information. The strongest evidence in support of this view is the set of findings indicating that when remote memories are retrieved, in either human or animal subjects that have suffered hippocampal system damage, these memories are not qualitatively the same as remote memories retrieved in intact subjects. In sum, memory appears to be rather more dynamic than most current conceptions allow, such that retrieval events trigger new encodings, and these new encodings engage the hippocampal system once again. As a result, older, reactivated memories become more resistant to disruption, and this mechanism helps to explain why graded retrograde amnesia is sometimes seen after brain damage. The use of new neuroimaging techniques, coupled with more sensitive neuropsychological tests in lesioned subjects, should further illuminate the complex nature of memory in coming years. It is likely that animal studies will continue to prove important in these developments.
• Nadel, L., & Moscovitch, M. (2001). The hippocampal complex and long-term memory revisited. Trends in Cognitive Sciences, 5(6), 228-230.
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  Abstract: A recent report by Cipolotti et al. demontrates that the hippocampus and perhaps the parahippocampal area are essential for retrieval of remote episodic memory and important for remote semantic memory. This report, along with other recent findings, re-opens the debate about the role of these medial temporal lobe structures, indicating that their role extends much further than traditional theory had suggested. Copyright © 2001 Elsevier Science Ltd.
• Baddeley, A., Bueno, O., Cahill, L., Fuster, J. M., Izquierdo, I., McGaugh, J. L., Morris, R. G., Nadel, L., Routtenberg, A., Xavier, G., & Cunha, C. D. (2000). The brain decade in debate: I. Neurobiology of learning and memory. Brazilian Journal of Medical and Biological Research, 33(9), 993-1002.
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  PMID: 10973129;Abstract: This article is a transcription of an electronic symposium in which some active researchers were invited by the Brazilian Society for Neuroscience and Behavior (SBNeC) to discuss the last decade's advances in neurobiology of learning and memory. The way different parts of the brain are recruited during the storage of different kinds of memory (e.g., short-term vs long-term memory, declarative vs procedural memory) and even the property of these divisions were discussed. It was pointed out that the brain does not really store memories, but stores traces of information that are later used to create memories, not always expressing a completely veridical picture of the past experienced reality. To perform this process different parts of the brain act as important nodes of the neural network that encode, store and retrieve the information that will be used to create memories. Some of the brain regions are recognizably active during the activation of short-term working memory (e.g., prefrontal cortex), or the storage of information retrieved as long-term explicit memories (e.g., hippocampus and related cortical areas) or the modulation of the storage of memories related to emotional events (e.g., amygdala). This does not mean that there is a separate neural structure completely supporting the storage of each kind of memory but means that these memories critically depend on the functioning of these neural structures. The current view is that there is no sense in talking about hippocampus-based or amygdala-based memory since this implies that there is a one-to-one correspondence. The present question to be solved is how systems interact in memory. The pertinence of attributing a critical role to cellular processes like synaptic tagging and protein kinase A activation to explain the memory storage processes at the cellular level was also discussed.
• Bohbot, V. D., J., J., & Nadel, L. (2000). Memory deficits characterized by patterns of lesions to the hippocampus and parahippocampal cortex. Annals of the New York Academy of Sciences, 911, 355-368.
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  PMID: 10911885;Abstract: Spatial and nonspatial memory tests were given to patients with small thermal lesions administered to the medial temporal lobes in an attempt at alleviating pharmacologically resistant epilepsy. In all three spatial memory experiments presented in this paper, patients with lesions that included the right parahippocampal cortex were seriously impaired. Their impairment, together with the performance of patients with lesions to the right hippocampus (sparing the right parahippocampal cortex), provides the different patterns of deficits that lead to different interpretations of the function of the parahippocampal cortex. The distinction between the effects of functional damage in hippocampus and the effects of a lesion to the hippocampus or to regions surrounding the hippocampus, such as the parahippocampal cortex, is emphasized. We conclude that the right parahippocampal cortex participates in spatial memory beyond serving as a gateway to the hippocampus.
• Nadel, L. (2000). Meeting on The Parahippocampal Region: Basic Science and Clinical Implications, Baltimore, 23-26 September 1999. Hippocampus, 10(2), 133-135.
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  PMID: 10791834;
• Nadel, L., & Land, C. (2000). Memory traces revisited. Nature Reviews Neuroscience, 1(3), 209-212.
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  PMID: 11257909;Abstract: Recent findings on the possibility of disrupting a stable memory after retrieval challenge some of our widely accepted views on memory consolidation.This article comments on the implications of these and earlier findings to our understanding of consolidation, and explores their possible relationship to the idea that retrieval creates a new memory trace, increasing the resistance of older memories to disruption.
• Nadel, L., Samsonovich, A., Ryan, L., & Moscovitch, M. (2000). Multiple trace theory of human memory: Computational, neuroimaging, and neuropsychological results. Hippocampus, 10(4), 352-368.
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  PMID: 10985275;Abstract: Hippocampal-neocortical interactions in memory have typically been characterized within the ″standard model″ of memory consolidation. In this view, memory storage initially requires hippocampal linking of dispersed neocortical storage sites, but over time this need dissipates, and the hippocampal component is rendered unnecessary. This change in function over time is held to account for the retorgrade amnesia (RA) gradients often seen in patients with hippocampal damage. Recent evidence, however, calls this standard model into question, and we have recently proposed a new approach, the ″multiple memory trace″ (MMT) theory. In this view, hippocampal ensembles are always involved in storage and retrieval of episodic information, but semantic (gist) information can be established in neocortex, and will survive damage to the hippocampal system if enough time has elapsed. This approach accounts more readily for the very long RA gradients often observed in amnesia. We report the results of analytic and connectionist simulations that demonstrate the feasibility of MMT. We also report a neuroimaging study showing that retrieval of very remote (25-year-old) memories elicits as much activation in hippocampus as retrieval of quite recent memories. Finally, we report new data from the study of patients with temporal lobe damage, using more sensitive measures than previously the case, showing that deficits in both episodic and spatial detail can bed observed even for very remote memories. Overall, these findings indicate that the standard model of memory consolidation, which views the hippocampus as having only a temporary role in memory, is wrong. Instead, the data support the view that for episodic and spatial detail the hippocampal system is always necessary. (C) 2000 Wiley-Liss, Inc.
• Rosenbaum, R. S., Priselac, S., Köhler, S., Black, S. E., Gao, F., Nadel, L., & Moscovitch, M. (2000). Remote spatial memory in an amnesic person with extensive bilateral hippocampal lesions. Nature Neuroscience, 3(10), 1044-1048.
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  PMID: 11017178;Abstract: The hippocampus may have a time-limited role in memory, being needed only until information is permanently stored elsewhere, or this region may permanently represent long-term allocentric spatial information or cognitive maps in memory. To test these ideas, we investigated remote spatial memory in K.C., a patient with bilateral hippocampal lesions and amnesia for autobiographical events. In his spatial knowledge, general aspects were preserved, but details were lost, a pattern that resembled his memory loss in other domains. K.C. performed normally on allocentric spatial tests of his neighborhood and the world. He had difficulty, however, in recognizing and identifying non-salient neighborhood landmarks, and in recognizing city locations on world maps. This suggests that the hippocampus is not crucial for maintenance and retrieval of remotely formed spatial representations of major landmarks, routes, distances and directions, but is necessary for specifying location details, regardless of when they were acquired.
• Jacobs, W. J., & Nadel, L. (1999). The first panic attack: A neurobiological theory. Canadian Journal of Experimental Psychology, 53(1), 92-107.
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  Abstract: We extend a neurodevelopmental model of specific phobias to the etiology of an initial panic attack and its elaboration into panic disorder. An important difference between the initial panic attack and specific phobia is the developmental timing of critical emotional experience: Those occurring early in development lead to panic; those occurring later in development lead to specific phobia. By this account, sensory and emotional experiences that occur early in development are stored in a set of modules, each with a unique developmental trajectory. Reinstatement, which occurs during hormonal stress, produces an aggregate of sensory and emotional memories and the first experience of an unexplained panic attack. Panic disorder, which evolves from unexplained panic attacks, involves retrieval of a disaggregate set of sensory and emotional memory fragments supplemented by an inferential fitting of an explanatory context to this incomplete aggregate.
• Jacobs, W. J., & Nadel, L. (1999). The first panic attack: a neurobiological theory.. Canadian journal of experimental psychology = Revue canadienne de psychologie expérimentale, 53(1), 92-107.
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  PMID: 10389492;Abstract: We extend a neurodevelopmental model of specific phobias to the etiology of an initial panic attack and its elaboration into panic disorder. An important difference between the initial panic attack and specific phobia is the developmental timing of critical emotional experience: Those occurring early in development lead to panic; those occurring later in development lead to specific phobia. By this account, sensory and emotional experiences that occur early in development are stored in a set of modules, each with a unique developmental trajectory. Reinstatement, which occurs during hormonal stress, produces an aggregate of sensory and emotional memories and the first experience of an unexplained panic attack. Panic disorder, which evolves from unexplained panic attacks, involves retrieval of a disaggregate set of sensory and emotional memory fragments supplemented by an inferential fitting of an explanatory context to this incomplete aggregate.
• Moscovitch, M., & Nadel, L. (1999). Multiple-trace theory and semantic dementia: Response to K.S. Graham (1999). Trends in Cognitive Sciences, 3(3), 87-89.
• Nadel, L., & Eichenbaum, H. (1999). Introduction to the special issue on place cells. Hippocampus, 9(4), 341-345.
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  PMID: 10495016;
• Nadel, L., Ryan, L., Keil, K., & Putnam, K. (1999). Episodic memory: It's about time (and space). Behavioral and Brain Sciences, 22(3), 463-464.
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  Abstract: Aggleton and Brown rightly point out the shortcomings of the medial temporal lobe hypothesis as an approach to anterograde amnesia. Their broader perspective is a necessary corrective, and one hopes it will be taken very seriously. Although they correctly note the dangers of conflating recognition and recall, they themselves make a similar mistake in discussing familiarity; we suggest an alternative approach. We also discuss implications of their view for an analysis of retrograde amnesia. The notion that there are two routes by which the hippocampus can reactivate neuronal ensembles in the neocortex could help us understand some currently puzzling facts about the dynamics of memory consolidation.
• Bohbot, V. D., Kalina, M., Stepankova, K., Spackova, N., Petrides, M., & Nadel, L. (1998). Spatial memory deficits in patients with lesions to the right hippocampus and to the right parahippocampal cortex. Neuropsychologia, 36(11), 1217-1238.
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  PMID: 9842767;Abstract: Spatial memory tasks, performance of which is known to be sensitive to hippocampal lesions in the rat, or to medial temporal lesions in the human, were administered in order to investigate the effects of selective damage to medial temporal lobe structures of the human brain. The patients had undergone thermo-coagulation with a single electrode along the amygdalohippocampal axis in an attempt to alleviate their epilepsy. With this surgical technique, lesions to single medial temporal lobe structures can be carried out. The locations of the lesions were assessed by means of digital high-resolution magnetic resonance imaging and software allowing a 3-D reconstruction of the brain. A break in the collateral sulcus, dividing it into the anterior collateral sulcus and the posterior collateral sulcus is reported. This division may correspond to the end of the entorhinal/perirhinal cortex and the start of the parahippocampal cortex. The results confirmed the role of the right hippocampus in visuo-spatial memory tasks (object location, Rey-Osterrieth Figure with and without delay) and the left for verbal memory tasks (Rey Auditory Verbal Learning Task with delay). However, patients with lesions either to the right or to the left hippocampus were unimpaired on several memory tasks, including a spatial one, with a 30 min delay, designed to be analogous to the Morris water maze. Patients with lesions to the right parahippocampal cortex were impaired on this task with a 30 min delay, suggesting that the parahippocampal cortex itself may play an important role in spatial memory.
• Czéh, B., Seress, L., Nadel, L., & Bures, J. (1998). Lateralized fascia dentata lesion and blockade of one hippocampus: Effect on spatial memory in rats. Hippocampus, 8(6), 647-650.
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  PMID: 9882022;Abstract: Unilateral blockade of the dorsal hippocampus by tetrodetoxin makes it possible to form lateralized spatial memories, which rapidly transfer to the naive hippocampus when training continues with intact brain. Unilateral X-ray irradiation of newborn rats causes irreversible destruction of granule cells in the ipsilateral fascia dentata (FD). Possible compensation of poor learning in the lesioned hemisphere by commissural transfer of memories from the intact hippocampus was examined in seven rats with unilateral FD lesion, which were first trained in the Morris water maze to asymptotic performance (mean escape latency 6 ± 1 s). Subsequent testing during functional ablation either of the intact or of the lesioned hippocampus by tetrodotoxin revealed escape latencies 35 ± 8 s or 8 ± 1 s, respectively. Probe trial tests during inactivation of the intact and lesioned hippocampus showed target quadrant preference of 32 ± 2% or 54 ± 3%, respectively. The results indicate: (a) that one intact hippocampus alone can support the water maze task, (b) that no, or only a very weak, memory trace is available in the lesioned hippocampus. It is concluded that the above results are due to the inability of the FD lesioned hippocampus to process the information received from the ipsilateral entorhinal cortex.
• Jacobs, W. J., & Nadel, L. (1998). Neurobiology of reconstructed memory. Psychology, Public Policy, and Law, 4(4), 1110-1134.
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  Abstract: The authors present evidence that normal autobiographical memories and "recovered" autobiographical memories of long-forgotten traumatic events are produced by the same mechanisms. The basic process involves the parallel storage of information in a set of independent modules, the selective retrieval and reaggregation of this dispersed information within an appropriate spatiotemporal context, and the organization of this aggregate by a narrative. The result is a seamless blend of retrieved information (that which is recalled) and knowledge (that which is inferred) experienced as an autobiographical memory. The critical difference between normal and recovered memories, by this account, is the impact of trauma on the storage process: The physiological consequences of trauma can include a disabling of the neural module responsible for encoding the appropriate spatiotemporal context. Recovered memory involves retrieval of memory fragments, confabulation (innocent or not) driven by inference, and the fitting of a context to this incomplete aggregate. This too is experienced as an autobiographical memory. The implications of this view for estimating the veridicality of recovered memories are discussed.
• Jacobs, W. J., G., K., Laurance, H. E., & Nadel, L. (1998). Place Learning in Virtual Space: II. Topographical Relations as One Dimension of Stimulus Control. Learning and Motivation, 29(3), 288-308.
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  Abstract: Three experiments using human participants examined a major prediction derived from cognitive mapping theory of place learning: In the absence of proximal cues, place performance depends on relations among distal cues. Experiments 1 and 2 showed that, after learning to find an invisible target in computer-generated (C-G) space, removing the full set of distal stimuli disrupted place performance but removing subsets of distal stimuli did not. These results demonstrate that the full array of distal cues are critical to stimulus control of place performance in this C-G space whereas individual stimuli are not. Experiment 3 showed that, after learning to find an invisible target in the same C-G space, changes in topographical relations among the distal stimuli disrupted place performance. As predicted by cognitive mapping theory, the results suggest that participants use relations among distal cues to guide place performance in C-G space. In addition, the results support the assertion that place learning in C-G space is comparable to both rat and human place learning in mundane space. © 1998 Academic Press.
• Moscovitch, M., & Nadel, L. (1998). Consolidation and the hippocampal complex revisited: In defense of the multiple-trace model. Current Opinion in Neurobiology, 8(2), 297-300.
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  PMID: 9635217;
• Nadel, L., & Jacobs, W. J. (1998). Traumatic memory is special. Current Directions in Psychological Science, 7(5), 154-157.
• Nadel, L., & Moscovitch, M. (1998). Hippocampal contributions to cortical plasticity. Neuropharmacology, 37(4-5), 431-439.
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  PMID: 9704984;Abstract: The hippocampal complex and neocortex are both integrally important in memory function, in particular as regards memory for episodes and knowledge about the world that is derived from them. It is traditionally assumed that the role of the hippocampus is time-limited, after which retrieval of episodic memory depends only upon neocortical stores. A number of lines of evidence indicate that this traditional view is incorrect. We propose that the hippocampal complex is always necessary for retrieval of episodes and their contextual frame, and that hippocampal-neocortical interactions contribute instead to the extraction of semantic information to be stored in the neocortex.
• Uecker, A., & Nadel, L. (1998). Spatial but not object memory impairments in children with fetal alcohol syndrome. American Journal on Mental Retardation, 103(1), 12-18.
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  PMID: 9678226;Abstract: Behavioral dissociations on tests of cognitive abilities are powerful tools that can help define the neuropsychology of developmentally disabling conditions. Animals gestationally exposed to alcohol demonstrate spatial (place) but not object (cue) memory impairments. Whether children with fetal alcohol syndrome demonstrate a similar dissociation has received little attention. In this experiment, 30 Native American children, 15 previously identified with fetal alcohol syndrome and 15 control children, were asked to recall places and objects in a task previously shown to be sensitive to memory skills in individuals with and without mental retardation. As in animal models, children with fetal alcohol syndrome demonstrated a spatial but not an object memory impairment. A possible role for the hippocampus was discussed.
• Bohbot, V. D., Nadel, L., Jech, R., Ruzicka, E., & Bures, J. (1997). Spatial and nonspatial memory involvement in myasthenia gravis [2]. Journal of Neurology, 244(8), 529-532.
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  PMID: 9309563;
• Bohbot, V., Kalina, M., Stepankova, K., Spackova, N., Petrides, M., & Nadel, L. (1997). Lesions to the right parahippocampal cortex cause navigational memory deficits in humans. NeuroImage, 5(4 PART II), S626.
• Czurkó, A., Czéh, B., Seress, L., Nadel, L., & Bures, J. (1997). Severe spatial navigation deficit in the Morris water maze after single high dose of neonatal x-ray irradiation in the rat. Proceedings of the National Academy of Sciences of the United States of America, 94(6), 2766-2771.
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  PMID: 9122269;PMCID: PMC20165;Abstract: Ambiguous spatial behavior deficits induced in adult rats by different types of dentate gyrus lesions were examined by subjecting neonatal rats to x-ray irradiation, which reduces the granule cell population in fascia dentata without affecting the number of hilar neurons and pyramidal cells of Ammon's horn. Three- to six-month-old irradiated and intact male Long-Evans rats were tested in the Morris water maze. Four experiments were done. (i) Rats were trained to find an invisible escape platform, when started from any of four equidistant points at the circumference of the pool. (ii) The same rats then were trained to find a visible platform in the same pool. Poor performance of irradiated rats in both experiments suggested a visual deficit. (iii) Navigation in the absence of visual cues was studied in other rats trained in total darkness to find the escape platform under conditions of fixed start-fixed goal geometry. (iv) Contribution of nonvisual allocentric cues and egocentric path integration mechanisms to spatial performance of the above rats was tested in darkness after rotating both the start and goal positions by 90°clockwise. Impairment of irradiated rats in Exp. 3 and 4 and histological examination of their brains support the conclusion that 60-70% reduction of granule cells in the dorsal hippocampus causes significant deterioration in both allocentric and egocentric orientation.
• Nadel, L., & Moscovitch, M. (1997). Memory consolidation, retrograde amnesia and the hippocampal complex. Current Opinion in Neurobiology, 7(2), 217-227.
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  PMID: 9142752;Abstract: Results from recent studies of retrograde amnesia following damage to the hippocampal complex of human and non-human subjects have shown that retrograde amnesia is extensive and can encompass much of a subject's lifetime; the degree of loss may depend upon the type of memory assessed. These and other findings suggest that the hippocampal formation and related structures are involved in certain forms of memory (e.g. autobiographical episodic and spatial memory) for as long as they exist and contribute to the transformation and stabilization of other forms of memory stored elsewhere in the brain.
• Bohbot, V., Otahal, P., Liu, Z., Nadel, L., & Bures, J. (1996). Erratum: Electroconvulsive shock and lidocaine reveal rapid consolidation of spatial working memory in the water maze (Proceedings of the National Academy of Science of the United States of America (April 30, 1996) 93:9 (4016-4019)). Proceedings of the National Academy of Sciences of the United States of America, 93(16), 8796-.
• Bohbot, V., Otáhal, P., Liu, Z., Nadel, L., & Bures, J. (1996). Electroconvulsive shock and lidocaine reveal rapid consolidation of spatial working memory in the water maze. Proceedings of the National Academy of Sciences of the United States of America, 93(9), 4016-4019.
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  PMID: 8633008;PMCID: PMC39478;Abstract: Head trauma leading to concussion and electroconvulsive shock (ECS) in humans causes amnesia for events that occurred shortly before the injury (retrograde amnesia). The present experiment investigated the amnesic effect of lidocaine and ECS in 25 rats trained on a working memory version of the Morris water task. Each day, the escape platform was moved to a new location; learning was evidenced by a decrease in the latency to find the platform from the first to the second trial. 'Consolidation' of this newly encoded spatial engram was disrupted by bilateral inactivation of the dorsal hippocampus with 1 μl of 4% lidocaine applied as soon as possible after the first trial. When trial 2 was given after recovery from the lidocaine (30 min after the injection), a normal decrease in latency indicated that the new engram was not disrupted. When trial 2 was given under the influence of lidocaine (5 min after injection), absence of latency decrease demonstrated both the success of the inactivation and the importance of hippocampus for the task. To examine the role of events immediately after learning, ECS (30 or 100 mA, 50 Hz, 1.2 sec) was applied 0 sec to 45 sec after a single escape to the new platform location. A 2-h delay between ECS and trial 2 allowed the effects of ECS to dissipate. ECS applied 45 sec or 30 sec after trial 1 caused no retrograde amnesia: escape latencies on trial 2 were the same as in control rats. However, ECS applied 0 see or 15 sec after trial 1 induced clear retrograde amnesia: escape latencies on trial 2 were no shorter than on trial 1. It is concluded that the consolidation of a newly formed memory for spatial location can only be disrupted by ECS within 30 sec after learning.
• Jacobs, W. J., Laurance, H. E., Thomas, K. G., Luzcak, S. E., & Nadel, L. (1996). On the veracity and variability of traumatic memory. Traumatology, 2(2), 15-22.
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  Abstract: We specify conditions under which a memory for a traumatic event has a high, medium, or low probability of accurately reflecting the target event. In addition, we specify circumstances under which a second party may have a large, medium, or minimal influence on the content of traumatic memory. © 1996 Traumatology Forum.
• Uecker, A., & Nadel, L. (1996). Spatial locations gone awry: Object and spatial memory deficits in children with fetal alcohol syndrome. Neuropsychologia, 34(3), 209-223.
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  PMID: 8868278;Abstract: Hippocampus vulnerability following gestational alcohol exposure has been demonstrated neuroanatomically and behaviorally in animal models of fetal alcohol syndrome (FAS). There have been no similar demonstrations in humans. The Smith and Milner (1981) Memory for 16 Objects task has been used to explore the effects of right vs left temporal lobectomy with varying degrees of damage to the hippocampus. In the present experiment, this same task was administered to 15 children with FAS (mean age 10.03, S.D. = 2.33) and 15 control children (mean age 10.02, S.D. = 2.31). Similar to patients with right temporal lobectomies and a large excision to the hippocampus, children with FAS were able to perform immediate but not delayed object recall, had a general spatial memory deficit (P < 0.05), and significantly distorted the spatial array (P < 0.05). Although these results are consistent with an interpretation of hippocampal dysfunction, gestational alcohol exposure is known to result in a wide-ranging spectrum of neuropsychological deficits that vary in both extent and severity. Visuospatial deficits on the Beery test of Visuomotor Integration and Clock Drawing are suggestive of the other neural regions that may be involved in producing the behavioral deficits in children with FAS.
• Wilcox, T., Nadel, L., & Rosser, R. (1996). Location memory in healthy preterm and full-term infants. Infant Behavior and Development, 19(3), 309-323.
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  Abstract: Current research suggests that preterm birth, in and of itself, can have important consequences for the development of cognitive abilities. The research reported here investigated the development of egocentric location memory, and related attention behaviors, in preterm and full-term infants. In Experiment 1, healthy preterm and full-term infants were tested longitudinally at 2.5, 4.5, and 6.5 months of age on a location memory task. The preterm infants were tested at corrected age (i.e., age since expected due date). In this task, infants saw a toy lion hidden at one of two identical locations, a delay was imposed (5, 10, and 30 s at 2.5, 4.5, and 6.5 months, respectively), and then the lion either reappeared at the correct location (expected test event) or at the incorrect location (unexpected test event). At each age tested, the infants looked significantly longer at the unexpected than expected event, as if they remembered the correct location of hiding and found the reappearance of the lion at the incorrect location surprising. There were no reliable differences between the full-term and preterm infants. Results from a control experiment (Experiment 1A) suggest that the longer looking times to the unexpected event were not due to superficial differences between the two test events. Examination of attention behaviors (i.e., mean length of looks and trial length) during the encoding period also revealed no reliable differences between the preterm and full-term infants. However, looking times to the test events, and mean length of looks during the encoding period, decreased reliably with age. Experiment 2 was conducted to investigate whether the observed changes in attention could be attributed repeated exposure to the test events or to longer delay intervals. The results of Experiment 2 suggest that the observed changes in attention were not due to either of these factors. Together, the results of Experiments 1 and 2 suggest that (a) even very young infants can represent and remember the location of a hidden object, (b) attention behaviors during the location memory task change reliably with age, and (c) uncomplicated premature birth has no obvious effect on the development of location memory and related attentional abilities during the first 6.5 months corrected age. © 1996 Ablex Publishing Corporation.
• Nadel, L., & Nadel, L. (1995). The role of the hippocampus in declarative memory: A comment on Zola-Morgan, Squire, and Ramus (1994). Hippocampus, 5(3), 232-239.
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  PMID: 7550618;
• Wilcox, T., Rosser, R., & Nadel, L. (1994). Representation of object location in 6.5-month-old infants. Cognitive Development, 9(2), 193-209.
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  Abstract: Within a small bounded space, the location of a hidden object can be coded in terms of distance information, general area of hiding, or the boundary of the space. 6.5-month-old infants' use of these three coding strategies was examined using a visual search task. Infants watched as an object was hidden at one of four identical locations. After a short delay (10 s), the object either reappeared at the location where it was hidden (possible event), or reappeared at one of the other three locations (impossible event). Looking behavior was not systematically influenced by the amount of distance the object moved from the original location of hiding or by whether the object was hidden near a boundary. Infants did not appear to code the location of a hidden object in terms of distance information, general area of hiding, or whether it was hidden at a boundary. However, the location of reappearance (i.e., impossible event) did influence looking times. Infants were surprised when the object reappeared at a boundary position that was previously unoccupied. They were not surprised when the object reappeared at a central location. Thus, two factors influenced coding of location: boundary information (but in a different way than specified) and the nature of the change (absence vs. presence of an object). The influence of these two factors on coding of spatial information was discussed. © 1994.
• Nadel, L. (1992). Multiple memory systems: What and why. Journal of Cognitive Neuroscience, 4(3), X1-188.
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  Abstract: Evidence from a variety of domains converges on the view that there are multiple learning/memory systems, but there is no clear understanding of what these systems are, and why they should exist. I review an hypothesis about multiple memory systems postulated by O'Keefe and Nadel (The hippocampus as a cognitive map, Oxford: Clarendon Press, 1978), in particular our assertions about the nature of two kinds of systems (the locale and taxon systems), and what differentiates them from each other. I concentrate on our assumption that systems differ in terms of the type of information they process, rather than in terms of the temporal duration over which they function. Our "content-driven" dichotomy is contrasted with several other current views, none of which appears to explain extant data, or provides clear predictions about when one or the other kind of system would be engaged. Finally, I briefly consider why such distinct systems might have evolved.
• Nadel, L. (1991). The hippocampus and space revisited.. Hippocampus, 1(3), 221-229.
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  PMID: 1669368;
• Polster, M. R., Nadel, L., & Schacter, D. L. (1991). Cognitive neuroscience analyses of memory: A historical perspective. Journal of Cognitive Neuroscience, 3(2), X1-116.
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  Abstract: As part of the general trend toward interdisciplinary research in recent years, a growing number of investigators have come to consider both cognitive and neuroscientific perspectives when theorizing about memory. Although such cognitive neuroscience analyses are a relatively recent development, the approach has precedents in earlier scientific thinking about memory. In this article we present a historical review of three major issues in memory research-consolidation processes, the nature of memory representations, and multiple memory systems. We discuss the nature of the relation between cognitive and neuroscientific approaches to each of these issues with respect to the distinction between collateral, complementary, and convergent relations (Schacter, 1986). Although some early investigators offered analyses that linked psychological and physiological perspectives, there is little historical evidence of systematic or sustained interdisciplinary research. However, more recent work, especially with respect to hypotheses about memory systems, suggests progress toward establishing programmatic interdisciplinary research.
• Nadel, L. (1990). Varieties of spatial cognition. Psychobiological considerations. Annals of the New York Academy of Sciences, 608, 613-636.
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  PMID: 2075964;
• Morris, R. G., Hagan, J. J., Nadel, L., Jensen, J., Baudry, M., & Lynch, G. S. (1987). Spatial learning in the rat: impairment induced by the thiol-proteinase inhibitor, leupeptin, and an analysis of [³H]glutamate receptor binding in relation to learning. Behavioral and Neural Biology, 47(3), 333-345.
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  PMID: 2886115;Abstract: Rats were given continuous intraventricular infusion of saline or the thiolproteinase inhibitor leupeptin, via subcutaneously implanted osmotic minipumps, while being trained on a spatial learning water task using spaced trials. Leupeptin caused overnight forgetting during training, but performance eventually reached asymptote in both groups. A retention test conducted 48 h later to assess spatial memory revealed no significant group differences, but did cause, in saline-treated rats only, a disruption of subsequent retraining back to the correct spatial location. The groups showed no differences in Cl-dependent [3H]glutamate receptor binding to hippocampal or entorhinal cortex membranes subsequent to training. In a second experiment, normal rats trained on the same task also showed no differences in Cl-dependent [3H]glutamate binding relative to rats exposed to the water task but given random spatial position training and handled controls. The results are discussed in relation to the hypothesis of Lynch and Baudry (Science (1984) 224, 1057-1063) that a calcium-dependent thiol proteinase is involved in memory formation through its ability to modify glutamate receptor distribution and dendritic spine shape. © 1987 Academic Press, Inc.
• Wilson, D. A., Willner, J., Kurz, E. M., & Nadel, L. (1986). Early handling increases hippocampal long-term potentiation in young rats. Behavioural Brain Research, 21(3), 223-227.
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  PMID: 3021181;Abstract: The hippocampal formation undergoes major anatomical and physiological changes postnatally, and thus might be expected to be particularly sensitive to early handling effects. Long-term potentiation (LTP) in the hippocampal formation, a form of brain plasticity thought to be important in learning and memory, was examined in young rats following early handling or control treatments. The amplitude of LTP was reliably greater in rats receiving the early handling regime. Possible mechanisms and consequences of enhanced LTP were discussed. © 1986.
• Jacobs, W. J., & Nadel, L. (1985). Stress-Induced Recovery of Fears and Phobias. Psychological Review, 92(4), 512-531.
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  PMID: 3903814;Abstract: Accounts of human fears and phobias based on current conditioning models using data from adults are examined and found wanting. Instead, the characteristics of human phobias resemble the kind of learning found during the amnesic period of infancy. As certain neural systems mature, conditioning begins to exhibit adult characteristics: context dependency, sharp generalization, and rapid extinction. Although direct behavioral control by the early learning systems wanes, the adult learning system seems to be structured at least partially through the lasting influence of infantile experience. Under (hormonal) stress, residues of early experience are reinstated and incorporated into adult memory where they directly control behavior. This control exhibits infantile characteristics. The evidence suggests that once acquired, such conditional fears might never be eliminated using traditional extinction or counterconditioning procedures. The view leads to a renewed emphasis upon the role of experience in human development, accepting the disproportionate importance of infant experience as the foundation upon which subsequent learning and cognitive function rest. © 1985 American Psychological Association.
• Squire, L. R., Nadel, L., & Slater, P. C. (1981). Anterograde amnesia and memory for temporal order. Neuropsychologia, 19(1), 141-145.
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  PMID: 7231659;Abstract: Because amnesic patients have great difficulty remembering the order in which events occur, anterograde amnesia has sometimes been considered to be a selective defect in this ability. The present study showed that temporal order information is fragile in normal subjects to the same extent as it is in amnesic patients. It is suggested that in many respects amnesic patients qualitatively resemble normal subjects tested long after learning. © 1981.
• Barnes, C. A., Nadel, L., & Honig, W. K. (1980). Spatial memory deficit in senescent rats.. Canadian journal of psychology, 34(1), 29-39.
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  PMID: 7388694;
• Nadel, L., & MacDonald, L. (1980). Hippocampus: Cognitive map or working memory?. Behavioral and Neural Biology, 29(3), 405-409.
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  PMID: 7417203;Abstract: The cognitive map theory of hippocampal function (O'Keefe & Nadel, 1978, The Hippocampus as a Cognitive Map, Oxford: Oxford Univ. Press) has recently been challenged by the assertion that this neural structure is involved in 'working memory' rather than mapping (Olton, Becker, & Handelmann, 1979, The Behavioral and Brain Sciences, 2, 313-365). In a within-subjects design where each lesioned animal served as its own control, rats were trained on two versions (PLACE and CUE) of a maze task designed to simultaneously assess long-term and short-term (working) memory function. After lesions in the hippocampus, rats rapidly regained criterion in the CUE task but not the PLACE task. Their performance was uninfluenced by the putative working memory aspects of the tasks. These data support cognitive map theory and its assertion that the defect following damage to the hippocampus is, at least in rats, selectively spatial.
• Nadel, L., & Willner, J. (1980). Context and conditioning: A place for space. Physiological Psychology, 8(2), 218-228.
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  Abstract: Notions about the influence of environmental context on behavior are briefly reviewed and criticized. In contrast to the traditional view that a context is merely a compound CS, to be treated in learning theory in much the same way as simple CSs, we propose that contexts are superordinate to such CSs. Within this hierarchical relation, a context both contains and predicts CSs. This approach to environmental context derives from cognitive map theory (O'Keefe & Nadel, 1978), and predictions based on that theory and the present extension are offered for several conditioning paradigms.
• O'Keefe, J., Nadel, L., & Willner, J. (1979). Tuning out irrelevancy? Comments on Solomon's temporal mapping view of the hippocampus. Psychological Bulletin, 86(6), 1280-1289.
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  PMID: 515283;Abstract: In his analysis of the present author's series of studies on the role of the hippocampus in spatial information processing (A. H. Black, L. Nadel, and J. O'Keefe; 1974, 1975, 1976, 1979), P. R. Solomon (see record 1980-04864-001) proposed an extension to the cognitive map theory of hippocampal function. He cites evidence drawn mainly from the literature on the classical conditioning of the rabbit's nictitating membrane response, which he claims can not be satisfactorily explained within the framework of the present theory. The present article shows that the deficits following hippocampal lesions can be predicted from understanding the role of place learning in each paradigm and shows that electrophysiological data are open to different interpretation. It is concluded that the data cited by Solomon do not require any modification of the theory. (2 p ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved).
• Black, A. H., Nadel, L., & O'Keefe, J. (1977). Hippocampal function in avoidance learning and punishment. Psychological Bulletin, 84(6), 1107-1129.
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  PMID: 928572;Abstract: Discusses the effects of hippocampal lesions in avoidance and punishment situations. It is proposed that animals with such lesions cannot process information about places and therefore cannot employ place strategies in avoidance learning and punishment situations; they can only employ cue strategies that involve learning to approach or avoid a cue or to perform a response in the presence of a cue. Intact animals, on the other hand, can employ both place and cue strategies. The data are, to a large extent, consistent with this hypothesis. Implications for theories of learning in situations involving aversive reinforcers are discussed. (125 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved). © 1977 American Psychological Association.
• Nadel, L., O'Keefe, J., & Black, A. (1975). Slam on the brakes: A critique of Altman, Brunner, and Bayer's response-inhibition model of hippocampal function. Behavioral Biology, 14(2), 151-162.
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  PMID: 1137539;Abstract: A recent paper by Altman, Brunner, and Bayer (1973) reviewed much of the literature on the hippocampus and suggested that this structure is involved in response 'braking.' However, their discussion of the data often failed to include all the relevant studies, and sometimes misinterpreted those that it did cite. We would contend that the literature does not support the response-braking model, and further, that their paper perpetuates a view of the hippocampus as an inhibitory structure which is neither supported by the data nor takes into account some interesting facets of the hippocampal syndrome. © 1975 Academic Press, Inc.
• O'Keefe, J., Nadel, L., Keightley, S., & Kill, D. (1975). Fornix lesions selectively abolish place learning in the rat. Experimental Neurology, 48(1), 152-166.
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  PMID: 1093867;Abstract: Rats with lesions in the fornix, a major afferent/efferent pathway of the hippocampus, failed on a water-finding task when place learning was required but succeeded in the same task when cue learning was required. These data, in conjunction with earlier physiological findings, indicate that the hippocampus functions as a cognitive mapping system. © 1975.
• Nadel, L. (1971). Interhemispheric transfer: Monocular input and varied sensory conditions. Physiology and Behavior, 6(6), 655-661.
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  PMID: 5148509;Abstract: The interhemispheric transfer of a visual discrimination was explored in rats. On Day 1 they were trained the task with one cortical hemisphere rendered non-functional by cortical spreading depression (CSD). This typically has the effect of limiting the information to the functional (trained) hemisphere. On Day 2 interdepression trials (IDT) were given with visual input limited to one eye, which has the effect of largely limiting the input to one hemisphere, either the trained hemisphere (the direct-access case, DA). or the untrained hemisphere (the indirect-access case, IA). On Day 3 savings were measured with either of the hemispheres depressed. Three basic IDT conditions were explored; (1) normal IDT, where IDT is identical with Day 1 training; (2) reversed IDT, where the stimuli during IDT are the reverse of that during Day 1 training; and, (3) non-specific IDT, where totally new stimuli are used during IDT. It was found that normal IDT facilitated transfer only under IA conditions, while reversed and non-specific IDT facilitated transfer only under DA conditions. It was further suggested that transfer under IA conditions is highly specific, while under DA conditions it involves perhaps two components, and is not specific to the training on Day 1. The results were discussed within the framework of a model of interhemispheric transfer involving two main components: (1) a trans-commissural write-in from the trained to the untrained hemisphere; and, (2) a comparison of the information transferred from the trained to the untrained hemisphere with the direct sensory input to the untrained hemisphere during IDT. © 1971.
• Burešová, O., & Nadel, L. (1970). Interhemispheric transfer in the rat. Physiology and Behavior, 5(8), 849-853.
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  PMID: 5522503;Abstract: The mechanisms of interhemispheric transfer of brightness or pattern discrimination were explored in rats, using cortical spreading depression (CSD) to achieve a functional split-brain. After monocular acquisition of the task retrieval was tested during unilateral CSD. The savings were 70 and 38 per cent for the primary trace (hemisphere contralateral to the open eye during initial acquisition) and secondary trace (hemisphere ipsilateral to the open eye) respectively. The secondary trace could not be improved by initial monocular overtraining. In a second study extensive monocular training was preceded by lateralized acquisition of the discrimination task (using CSD) in the primary hemisphere. Retention testing (under CSD) revealed a transferred trace similar to the secondary trace seen when monocular training was not preceded by lateralized training of the primary hemisphere. Thus, monocular training activates interhemispheric write-in processes yielding transferred traces which cannot be improved either by initial monocular overtraining or by prior lateralized training of the primary hemisphere. These results were compared to previous findings indicating that several monocular training trials given with input mainly directed to the untrained hemisphere (after prior lateralized acquisition under CSD) initiate a more powerful transfer. It is suggested that comparison of the transcommissurally transferred information with direct sensory input to the untrained hemisphere is a prerequisite of efficient interhemispheric transfer. © 1970.
• Nadel, L. (1970). Interhemispheric transfer and monoocular input: reversal trials.. Activitas Nervosa Superior, 12(2), 167-168.
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  PMID: 5443018;
• Nadel, L. (1969). Czechoslovakia: Extend a hand [2]. Science, 164(3880), 629-630.
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  PMID: 5778016;
• Nadel, L., & Burešová, O. (1969). Interocular transfer in the hooded rat. Physiology and Behavior, 4(4), 613-619.
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  Abstract: Cortical spreading depression was used as a means of providing a reversible split-brain in several experiments on interocular transfer in the hooded rat. It was shown that this phenomenon cannot be explained on the basis of the presence of a small number of ipsilateral fibers, but that central mechanisms are likely involved. Two such mechanisms were described: (1) the bilateral storage of memory traces during monocular learning, with the primary trace (hemisphere contralateral to the open eye) being stronger than the secondary trace (ipsilateral hemisphere); and, (2) the use of the traces in both hemispheres during monocular performance through the naive eye. Implications of these results for the general problem of interhemispheric communication are discussed. © 1969.
• Nadel, L. (1968). Dorsal and ventral hippocampal lesions and behavior. Physiology and Behavior, 3(6), 891-900.
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  Abstract: The behavior of rats with either dorsal or ventral hippocampal lesions was compared to that of a control group in a series of tests. Dorsal hippocampal lesions made rats hyperactive in novel situations, did not affect rates of habituation, facilitated acquisition of a conditioned emotional response (CER), and retarded acquisition of a one-way active avoidance response. Ventral hippocampal lesions made rats hyperactive in novel situations, affected the rate of habituation of exploratory responses, retarded extinction of the CER, and tended to facilitate acquisition of the one-way active avoidance response. These results demonstrate that the dorsal and ventral hippocampus are functionally distinct. When applied to an examination of previous data, this differentiation may help to clarify present confusion about hippocampal function. Possible functions of the dorsal and ventral areas are discussed. © 1968.
• Nadel, L., & Buresova, O. (1968). Monocular input and interhemispheric transfer in the reversible split-brain [20]. Nature, 220(5170), 914-915.
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  PMID: 5722141;Abstract: STUDIES in which sensory input is restricted to one cortical hemisphere have indicated that memory traces are established bilaterally and that the integrity of the corpus callosum is crucial to this dual trace system1. It seems that there is extensive communication between the two cortical hemispheres during both learning and retention. © 1968 Nature Publishing Group.

Proceedings Publications

• Newman-Smith, K., Yourison, R., Gerken, L., Bootzin, R. R., Nadel, L., Gomez, R. L., Newman-Smith, K., Yourison, R., Gerken, L., Bootzin, R. R., Nadel, L., & Gomez, R. L. (2012). State of rest in 17-month old infants differentially affects attention to new information. In Sleep, 35, A96.
• Spano, G., Anand, P., Breslin, J. H., Bootzin, R. R., Nadel, L., Edgin, J. O., Spano, G., Anand, P., Breslin, J. H., Bootzin, R. R., Nadel, L., & Edgin, J. O. (2012). Obstructive sleep apnea in Down Syndrome: Obesity correlates. In Sleep, 35, A379.

Presentations

• Nadel, L. -. (2007, 2007-04-01). Does spatial context play by associative rules.. Associative Learning Symposium. Gregynog, Wales, UK.
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  ;Invited: Yes;Type of Presentation: Invited/Plenary Speaker;
• Nadel, L. -. (2007, 2007-05-01). Hippocampus and memory.. Western Psychological Association. Vancouver.
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  ;Invited: Yes;Type of Presentation: Invited/Plenary Speaker;
• Nadel, L. -. (2007, 2007-06-01). Stress and human explicit memory: effects on encoding, consolidation and retrieval.. Dutch Endo-Neuro-Psycho Meeting. Doorwerth, The Netherlands.
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  ;Invited: Yes;Type of Presentation: Academic Conference;
• Nadel, L. -. (2007, 2007-09-01). Stress and human explicit memory: effects on encoding, consolidation and retrieval.. European Brain and Behavior Society. Trieste, Italy.
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  ;Invited: Yes;Type of Presentation: Academic Conference;
• Nadel, L. -., & Gomez, R. L. (2007, 2007-09-01). Reconsolidation in human episodic memory.. Memory Disorders Research Society. Cambridge, UK.
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  ;Your Role: Helped design research and write paper;Invited: Yes;Collaborative with faculty member in unit: Yes;Type of Presentation: Academic Conference/Workshop;
• Nadel, L. -., Breslin, J. H., Fridel, K. W., & Bootzin, R. R. (2007, 2007-02-01). Overnight Sleep-Dependent Visual Discrimination Task Improvement is Associated with Waking and Light Sleep. Associated Professional Sleep Societies.
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  ;Your Role: Helped design study and write abstract;Submitted: Yes;Collaborative with graduate student: Yes;Collaborative with faculty member in unit: Yes;Type of Presentation: Academic Conference;
• Nadel, L. -., Gomez, R. L., Hupbach, A., & Bootzin, R. B. (2007, 2007-09-01). The contribution of naps to infant learning and memory consolidation. Memory Disorders Research Society. Cambridge, UK.
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  ;Your Role: Helped design study and write abstract;Invited: Yes;Collaborative with faculty member in unit: Yes;Other collaborative: Yes;Specify other collaborative: Collaborative with faculty colleagues and postdoc;Type of Presentation: Academic Conference/Workshop;
• Nadel, L. -., Gomez, R., & Hupbach, A. (2007, 2007-04-01). How memory contributes to plasticity.. Society for Research on Child Development. Boston.
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  ;Your Role: Helped design study and write abstract;Invited: Yes;Collaborative with faculty member in unit: Yes;Other collaborative: Yes;Specify other collaborative: Collaborative with faculty colleague and postdoc;Type of Presentation: Academic Conference/Workshop;
• Nadel, L. -., Gomez, R., Hupbach, A., & Bootzin, D. (2007, 2007-05-01). The contribution of naps to infant learning.. Association for Psychological Science. Washington DC.
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  ;Your Role: Helped design study and write abstract;Submitted: Yes;Collaborative with faculty member in unit: Yes;Other collaborative: Yes;Specify other collaborative: Collaborative with faculty colleagues and postdoc;Type of Presentation: Academic Conference;
• Nadel, L. -., Hupbach, A., Gomez, ., & R.L., . (2007, 2007-12-01). Reconsolidation of episodic memories: A look at the conditions that trigger updating.. Psychonomic Society. Long Beach, CA.
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  ;Your Role: Helped design research and write abstract;Submitted: Yes;Collaborative with faculty member in unit: Yes;Other collaborative: Yes;Specify other collaborative: Collaborative with faculty colleague and postdoc;Type of Presentation: Academic Conference;
• Nadel, L. -., Hupbach, A., Gomez, R. L., & Hardt, O. (2007, 2007-04-01). Reconsolidation of children's episodic memories: A subtle reminder triggers integration of new information.. Society for Research in Child Development. Boston.
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  ;Your Role: Helped design study and write abstract;Submitted: Yes;Collaborative with faculty member in unit: Yes;Other collaborative: Yes;Specify other collaborative: Collaborative with faculty colleague and postdocs;Type of Presentation: Academic Conference;
• Nadel, L. -., Hupbach, A., Gomez, R. L., & Hardt, O. (2007, 2007-05-01). Updating Episodic Memories: A Special Role of Spatial Context. European Cognitive Science Conference. Greece.
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  ;Your Role: Helped design study and write abstract;Submitted: Yes;Collaborative with faculty member in unit: Yes;Other collaborative: Yes;Specify other collaborative: Collaborative with faculty colleague and postdocs;Type of Presentation: Academic Conference;
• Nadel, L. -., Hupbach, A., Hardt, O., Gomez, ., & R., . (2007, 2007-11-01). Reconsolidation of episodic memories: A look at the conditions that trigger updating.. Society for Neuroscience. San Diego.
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  ;Your Role: Helped design research and write abstract;Submitted: Yes;Collaborative with faculty member in unit: Yes;Other collaborative: Yes;Specify other collaborative: Collaborative with faculty colleague and postdocs;Type of Presentation: Academic Conference;
• Nadel, L. -., Lin, C., Ketcham, K., & Ryan, L. (2007, 2007-05-01). Common and differential brain regions associated with retrieving spatial and non-spatial information from episodic and semantic memory.. Cognitive Neuroscience Society. New York City.
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  ;Your Role: Helped design study and write abstract;Submitted: Yes;Collaborative with graduate student: Yes;Collaborative with faculty member in unit: Yes;Type of Presentation: Academic Conference;
• Nadel, L. -. (2006, 2006-01-01). Hippocampus and memory.. D.O. Hebb Lecture Series. McGill University.
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  ;Invited: Yes;Type of Presentation: Invited/Plenary Speaker;
• Nadel, L. -. (2006, 2006-04-01). Cognitive maps in the brain.. Louisville, KY.
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  ;Your Role: co-wrote;Invited: Yes;Type of Presentation: Grawemeyer Prize Lecture;
• Nadel, L. -., Breslin, J. H., Britton, W. B., Smith, L. J., & Bootzin, R. R. (2006, 2006-07-01). Both arousal and slow-wave sleep facilitate sleep-related memory.. American Psychological Society. New York City.
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  ;Your Role: Helped design study and write abstract;Submitted: Yes;Collaborative with graduate student: Yes;Collaborative with faculty member in unit: Yes;Type of Presentation: Academic Conference;
• Nadel, L. -., Breslin, J. H., Britton, W. B., Smith, L. J., & Bootzin, R. R. (2006, 2007-12-01). Both arousal and slow-wave sleep facilitate sleep-related memory.. Associated Professional Sleep Societies. Salt Lake City.
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  ;Your Role: Helped design study and write abstract;Submitted: Yes;Collaborative with graduate student: Yes;Collaborative with faculty member in unit: Yes;Type of Presentation: Academic Conference;
• Nadel, L. -., Cox, C., Hayes, S., Patterson, D., Ryan, ., & L., . (2006, 2006-10-01). Precuneus deactivations in a semantic memory retrieval task as measured by fMRI.. Society for Neuroscience. Atlanta.
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  ;Your Role: Helped design study and write abstract;Submitted: Yes;Collaborative with graduate student: Yes;Collaborative with faculty member in unit: Yes;Type of Presentation: Academic Conference;
• Nadel, L. -., Ellmore, T. M., Stouffer, K., & McNaughton, B. L. (2006, 2006-10-01). A measure of decision time changes as a function of the interval between the last successful trial of associative learning and the first successful retrieval attempt.. Society for Neuroscience. Atlanta.
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  ;Your Role: Helped design study and write abstract;Submitted: Yes;Collaborative with graduate student: Yes;Collaborative with faculty member in unit: Yes;Type of Presentation: Academic Conference;
• Nadel, L. -., Greenleaf, J. L., Ryan, ., & L., . (2006, 2006-10-01). Repeated memory retrieval results in schematization and decreased hippocampal activity.. Society for Neuroscience. Atlanta.
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  ;Your Role: Helped design study and write abstract;Submitted: Yes;Collaborative with graduate student: Yes;Collaborative with faculty member in unit: Yes;Type of Presentation: Academic Conference;
• Nadel, L. -. (2005, 2005-02-01). Down Syndrome: Toward Optimal Synaptic Function and Cognition. Down Syndrome Workshop. Washington, DC.
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  ;Invited: Yes;Type of Presentation: Academic Conference/Workshop;
• Nadel, L. -. (2005, 2005-03-01). Hippocampus: When and Where. International Neuropsychological Society. St. Louis.
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  ;Invited: Yes;Type of Presentation: Invited/Plenary Speaker;
• Nadel, L. -. (2005, 2005-04-01). Battig Memorial Lecture. Rocky Mountain Psychological Society. Phoenix, Arizona.
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  ;Invited: Yes;Type of Presentation: Invited/Plenary Speaker;
• Nadel, L. -. (2005, 2005-06-01). Assessing fMRI activation during encoding and retrieval of spatial contextual components of episodic memory.. Organization for Human Brain Mapping. Toronto, Canada.
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  ;Your Role: Helped design study and prepare talk.;Submitted: Yes;Collaborative with graduate student: Yes;Collaborative with faculty member in unit: Yes;Type of Presentation: Academic Conference;
• Nadel, L. -. (2005, 2005-08-01). Neal Miller Invited Lecture. American Psychological Association. Washington DC.
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  ;Invited: Yes;Type of Presentation: Invited/Plenary Speaker;
• Nadel, L. -., & Hupbach, A. (2005, 2005-10-01). Spatial reorientation: modular or flexible.. Cognitive Development Society. San Diego.
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  ;Your Role: Helped plan study and write abstract;Submitted: Yes;Other collaborative: Yes;Specify other collaborative: Collaborative with post-doc.;Type of Presentation: Academic Conference;
• Nadel, L. -., & Hupbach, A. (2005, 2005-11-01). Navigation and the geometric 'module': The case of re-orientation.. Workshop on Evolution and Spatial Cognition. Marseille, France.
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  ;Your Role: Wrote presentation and helped design research;Invited: Yes;Other collaborative: Yes;Specify other collaborative: Collaborative with postdoc;Type of Presentation: Academic Conference/Workshop;
• Nadel, L. -., Cox, C. L., Patterson, D. L., Ryan, ., & T., . (2005, 2005-11-01). Comparing real and imagined autobiographical event memories with fMRI.. Society for Neuroscience. Washington DC.
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  ;Your Role: Helped design study and write abstract;Submitted: Yes;Collaborative with graduate student: Yes;Collaborative with faculty member at UA: Yes;Type of Presentation: Academic Conference;
• Nadel, L. -., Gomez, R., & Bootzin, R. R. (2005, 2005-05-01). Sleep and memory consolidation in infant learning.. Conference on New Approaches to Infant Learning and Cognition. Duke University.
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  ;Your Role: Planned research;Invited: Yes;Collaborative with faculty member in unit: Yes;Type of Presentation: Academic Conference/Workshop;
• Nadel, L. -., Gomez, R., & Bootzin, R. R. (2005, 2005-10-01). Naps promote abstraction in language learning infants.. Cognitive Development Society. San Diego.
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  ;Your Role: Helped design study and write abstract;Submitted: Yes;Collaborative with faculty member in unit: Yes;Type of Presentation: Academic Conference;
• Nadel, L. -., Greenleaf, J. L., Ryan, ., & L., . (2005, 2005-11-01). Hippocampal activation as a function of repeated retrieval of episodic memories: an fMRI study.. Society for Neuroscience. Washington DC.
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  ;Your Role: Helped design study and write abstract;Submitted: Yes;Collaborative with graduate student: Yes;Collaborative with faculty member in unit: Yes;Type of Presentation: Academic Conference;
• Nadel, L. -., Hoscheidt, S. M., Payne, J. D., Patterson, D., Ryan, ., & L., . (2005, 2005-06-01). Varying Spatial Information in Semantic and Episodic Memory Retrieval: An fMRI Study.. Organization for Human Brain Mapping. Toronto, Canada.
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  ;Your Role: Helped design study and write abstract.;Submitted: Yes;Collaborative with graduate student: Yes;Collaborative with faculty member in unit: Yes;Type of Presentation: Academic Conference;
• Nadel, L. -., Hoscheidt, S. M., Payne, J. D., Patterson, D., Ryan, ., & L., . (2005, 2005-11-01). Retrieval of spatial information in semantic and episodic memory: an fMRI study.. Society for Neuroscience. Washington DC.
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  ;Your Role: Helped design study and write abstract;Submitted: Yes;Collaborative with graduate student: Yes;Collaborative with faculty member in unit: Yes;Type of Presentation: Academic Conference;
• Nadel, L. -., Jackson, E. D., Jacobs, ., & W.J., . (2005, 2007-11-01). Glucocorticoids impair the consolidation of emotional memories and fear conditioning in humans.. Society for Neuroscience. Washington DC.
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  ;Your Role: Helped design study and write abstract;Submitted: Yes;Collaborative with graduate student: Yes;Collaborative with faculty member in unit: Yes;Type of Presentation: Academic Conference;
• Nadel, L. -., Jackson, E. D., Spencer, A., Jacobs, ., & W.J., . (2005, 2005-07-01). Cortisol Inhibits Emotional Memory Consolidation in Humans. American Psychological Association. Los Angeles.
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  ;Your Role: Helped designed study and prepare abstract.;Submitted: Yes;Collaborative with undergraduate student: Yes;Collaborative with graduate student: Yes;Collaborative with faculty member in unit: Yes;Type of Presentation: Academic Conference;
• Nadel, L. -., Ketcham, K., & L., R. (2005, 2005-11-01). Hippocampal involvement in processing of spatial and other relational information.. Society for Neuroscience. Washington DC.
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  ;Your Role: Helped design study and write abstract.;Submitted: Yes;Collaborative with graduate student: Yes;Collaborative with faculty member in unit: Yes;Type of Presentation: Academic Conference;
• Nadel, L. -., Ryan, L., Cox, C., & Patterson, D. (2005, 2005-06-01). Comparing fMRI activation of real and imagined autobiographical event memories.. Organization for Human Brain Mapping. Toronto, Canada.
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  ;Your Role: Helped design study and write talk.;Submitted: Yes;Collaborative with graduate student: Yes;Collaborative with faculty member in unit: Yes;Type of Presentation: Academic Conference;
• Nadel, L. -., Thomas, K., Laurance, H. E., Hancock, T., Jacobs, ., & W., J. (2005, 2005-07-01). Exposure to acute stressors disrupts spatial cognition in females but not males.. American Psychological Association. Los Angeles.
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  ;Your Role: Helped write abstract;Submitted: Yes;Collaborative with undergraduate student: Yes;Collaborative with graduate student: Yes;Collaborative with faculty member in unit: Yes;Type of Presentation: Academic Conference;

Reviews

• Nadel, L. -. (2007. Review of Beyond 9 to 5: Your Life in Time.
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  ;Your Role: Wrote it.;Full Citation: Nadel, L. Review of Beyond 9 to 5: Your Life in Time by Sarah Norgate. Cerebrum, 2007.;
• Nadel, L. -. (2007. The Hippocampus Book: a Review.
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  ;Your Role: Wrote it;Full Citation: Nadel, L. The Hippocampus Book: a Review, Hippocampus, 17, 1013-1016, 2007.;

Creative Performances

• Nadel, L. (2014. A Stroll Down Memory Lane. ECE Summer School. Bochum, Germany.
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  Keynote Talk
• Nadel, L. (2013. Jan Bures: A Man for all Seasons. FENS Regional Meeting. Prague, Czech Republic.
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  Invited Talk
• Nadel, L. (2012. What is episodic memory for?. Summer Institute for Cognitive Neuroscience. Santa Barbara.
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  Invited lecture

Others

• Nadel, L. -. (2007). Cognitive Biology.
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  This is an edited book from a conference I co-organized in Vienna in 2006.;Collaborative with faculty member in unit: Yes;Other collaborative: Yes;Please specify if you select "Other collaborative" : Collaborative with colleagues at UA and in Italy;Full Citation: L. Tommassi, L. Nadel & M.A. Peterson (Eds.) Cognitive Biology, MIT Press, Cambridge, USA, in preparation.;Status: Submitted But Not Yet Accepted;
• Nadel, L. -. (2007). Handbook of Episodic Memory Research.
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  This is an edited book that is nearly ready to go to press.;Other collaborative: Yes;Please specify if you select "Other collaborative" : Collaborative with colleagues in the UK and Germany.;Full Citation: E. Dere, J. Huston, A. Easton & L. Nadel (Eds.) Handbook of Episodic Memory Research, Elsevier, London, UK, in preparation.;Status: Submitted But Not Yet Accepted;
• Nadel, L. -. (2007). Hippocampal Activation during Episodic and Semantic Memory Retrieval: Comparing Category Production and Category Cued Recall.
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  ;Collaborative with graduate student: Yes;Collaborative with faculty member in unit: Yes;Full Citation: Ryan, L., Cox. C., Hayes, S. & Nadel, L. Hippocampal Activation during Episodic and Semantic Memory Retrieval: Comparing Category Production and Category Cued Recall (Neuropsychologia, submitted);Status: Under Revision (Revise and Resubmit);
• Nadel, L. -. (2007). Stress induced impairment of spatial navigation in females: Implications for sex differences in anxiety disorders.
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  ;Collaborative with graduate student: Yes;Collaborative with faculty member in unit: Yes;Other collaborative: Yes;Please specify if you select "Other collaborative" : Collaborative with colleagues at UA and in South Africa;Full Citation: Thomas, K.G.F., Laurance, H.E., Nadel, L. & Jacobs, W.J. Stress induced impairment of spatial navigation in females: Implications for sex differences in anxiety disorders (South African Journal of Psychology, submitted);Status: Submitted But Not Yet Accepted;
• Nadel, L. -. (2007). The Dynamics of Memory: Context-Dependent Updating.
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  ;Collaborative with faculty member in unit: Yes;Other collaborative: Yes;Please specify if you select "Other collaborative" : Collaborative with postdocs;Full Citation: Hupbach, A., Hardt, O., Gomez, R. & Nadel, L. The Dynamics of Memory: Context-Dependent Updating (Psychological Bulletin & Review, submitted);Status: Submitted But Not Yet Accepted;
• Nadel, L. -. (2007). Thigmotaxis navigation strategy and hippocampus volumetry: A study with Morris type mazes and the neurobehavioural correlates of spatial learning and strategy in female subjects.
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  ;Collaborative with faculty member at UA: Yes;Other collaborative: Yes;Please specify if you select "Other collaborative" : Collaborative with colleagues at UA and in Hungary;Full Citation: Kallai, J., Makany, T., Horvath, D., Csathu, A., Karadi, K., Kovacs, N., Kver, F., Horvath, K., Jacobs, W. J., Nagy, F., Nadel, L. Thigmotaxis navigation strategy and hippocampus volumetry: A study with Morris type mazes and the neurobehavioural correlates of spatial learning and strategy in female subjects. (Behavioural Brain Research, submitted) ;Status: Submitted But Not Yet Accepted;