101
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Spanò G, Intraub H, Edgin JO. Testing the "Boundaries" of boundary extension: Anticipatory scene representation across development and disorder. Hippocampus 2017; 27:726-739. [PMID: 28329909 DOI: 10.1002/hipo.22728] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2016] [Revised: 01/14/2017] [Accepted: 01/19/2017] [Indexed: 12/28/2022]
Abstract
Recent studies have suggested that Boundary Extension (BE), a scene construction error, may be linked to the function of the hippocampus. In this study, we tested BE in two groups with variations in hippocampal development and disorder: a typically developing sample ranging from preschool to adolescence and individuals with Down syndrome. We assessed BE across three different test modalities: drawing, visual recognition, and a 3D scene boundary reconstruction task. Despite confirmed fluctuations in memory function measured through a neuropsychological assessment, the results showed consistent BE in all groups across test modalities, confirming the near universal nature of BE. These results indicate that BE is an essential function driven by a complex set of processes, that occur even in the face of delayed memory development and hippocampal dysfunction in special populations.
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Affiliation(s)
- G Spanò
- Department of Psychology, University of Arizona, Tucson, Arizona, 85721.,Cognitive Science Program, University of Arizona, Tucson, Arizona, 85721
| | - H Intraub
- Department of Psychological and Brain Sciences, University of Delaware, Newark, Delaware, 19716
| | - J O Edgin
- Department of Psychology, University of Arizona, Tucson, Arizona, 85721.,Cognitive Science Program, University of Arizona, Tucson, Arizona, 85721.,Sonoran University Center for Excellence in Developmental Disabilities, University of Arizona, Tucson, Arizona, 85721
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102
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Chavlis S, Poirazi P. Pattern separation in the hippocampus through the eyes of computational modeling. Synapse 2017; 71. [PMID: 28316111 DOI: 10.1002/syn.21972] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 03/02/2017] [Accepted: 03/14/2017] [Indexed: 12/24/2022]
Abstract
Pattern separation is a mnemonic process that has been extensively studied over the years. It entails the ability -of primarily hippocampal circuits- to distinguish between highly similar inputs, via generating different neuronal activity (output) patterns. The dentate gyrus (DG) in particular has long been hypothesized to implement pattern separation by detecting and storing similar inputs as distinct representations. The ways in which these distinct representations can be generated have been explored in a number of theoretical and computational modeling studies. Here, we review two categories of pattern separation models: those that address the phenomenon in an abstract mathematical fashion and those that delve into the underlying biological mechanisms by taking into account the anatomy and/or physiology of hippocampal circuits. We summarize the strategies, findings and limitations of these modeling approaches in the light of new experimental findings and propose a unifying framework whereby different network, cellular and sub-cellular mechanisms converge to a common goal: controlling sparsity, the key determinant of pattern separation in the DG.
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Affiliation(s)
- Spyridon Chavlis
- Institute of Molecular Biology & Biotechnology (IMBB), Foundation for Research and Technology - Hellas (FORTH), N. Plastira 100, Heraklion, Crete, 70013, Greece.,Department of Biology, University of Crete, Vasilika Vouton, P.O. Box 2208, Heraklion, Crete, 71409, Greece
| | - Panayiota Poirazi
- Institute of Molecular Biology & Biotechnology (IMBB), Foundation for Research and Technology - Hellas (FORTH), N. Plastira 100, Heraklion, Crete, 70013, Greece
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103
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Kinnavane L, Amin E, Olarte-Sánchez CM, Aggleton JP. Medial temporal pathways for contextual learning: Network c- fos mapping in rats with or without perirhinal cortex lesions. Brain Neurosci Adv 2017; 1:2398212817694167. [PMID: 28685167 PMCID: PMC5496664 DOI: 10.1177/2398212817694167] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 01/25/2017] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND In the rat brain, context information is thought to engage network interactions between the postrhinal cortex, medial entorhinal cortex, and the hippocampus. In contrast, object information is thought to be more reliant on perirhinal cortex and lateral entorhinal cortex interactions with the hippocampus. METHOD The 'context network' was explored by mapping expression of the immediate-early gene, c-fos, after exposure to a new spatial environment. RESULTS Structural equation modelling of Fos counts produced networks of good fit that closely matched prior predictions based on anatomically-grounded functional models. These same models did not, however, fit the Fos data from home-cage controls nor did they fit the corresponding data from a previous study exploring object recognition. These additional analyses highlight the specificity of the context network. The home-cage controls, meanwhile, showed raised levels of inter-area Fos correlations between the many sites examined, i.e., their changes in Fos levels lacked anatomical specificity. Two additional groups of rats received perirhinal cortex lesions. While the loss of perirhinal cortex reduced lateral entorhinal c-fos activity, it did not affect mean levels of hippocampal c-fos expression. Similarly, overall c-fos expression in the prelimbic cortex, retrosplenial cortex and nucleus reuniens of the thalamus appeared unaffected by the perirhinal cortex lesions. CONCLUSION The perirhinal cortex lesions disrupted network interactions involving the medial entorhinal cortex and the hippocampus, highlighting ways in which perirhinal cortex might affect specific aspects of context learning.
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Affiliation(s)
| | - Eman Amin
- School of Psychology, Cardiff University, Cardiff, UK
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104
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Kalweit AN, Amanpour-Gharaei B, Colitti-Klausnitzer J, Manahan-Vaughan D. Changes in Neuronal Oscillations Accompany the Loss of Hippocampal LTP that Occurs in an Animal Model of Psychosis. Front Behav Neurosci 2017; 11:36. [PMID: 28337131 PMCID: PMC5340772 DOI: 10.3389/fnbeh.2017.00036] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 02/21/2017] [Indexed: 12/17/2022] Open
Abstract
The first-episode of psychosis is followed by a transient time-window of ca. 60 days during which therapeutic interventions have a higher likelihood of being effective than interventions that are started with a greater latency. This suggests that, in the immediate time-period after first-episode psychosis, functional changes occur in the brain that render it increasingly resistant to intervention. The precise mechanistic nature of these changes is unclear, but at the cognitive level, sensory and hippocampus-based dysfunctions become increasingly manifest. In an animal model of first-episode psychosis that comprises acute treatment of rats with the irreversible N-methyl-D-aspartate receptor (NMDAR)-antagonist, MK801, acute but also chronic deficits in long-term potentiation (LTP) and spatial memory occur. Neuronal oscillations, especially in the form of information transfer through θ and γ frequency oscillations are an intrinsic component of normal information processing in the hippocampus. Changes in θ-γ coupling and power are known to accompany deficits in hippocampal plasticity. Here, we examined whether changes in δ, θ, α, β and γ oscillations, or θ-γ coupling accompany the chronic loss of LTP that is observed in the MK801-animal model of psychosis. One and 4 weeks after acute systemic treatment of adult rats with MK801, a potent loss of hippocampal in vivo LTP was evident compared to vehicle-treated controls. Overall, the typical pattern of θ-γ oscillations that are characteristic for the successful induction of LTP was altered. In particular, θ-power was lower and an uncoupling of θ-γ oscillations was evident in MK801-treated rats. The alterations in network oscillations that accompany LTP deficits in this animal model may comprise a mechanism through which disturbances in sensory information processing and hippocampal function occur in psychosis. These data suggest that the hippocampus is likely to comprise a very early locus of functional change after instigation of a first-episode psychosis-like state in rodents.
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Affiliation(s)
- Alexander N Kalweit
- Department of Neurophysiology, Medical Faculty, Ruhr University BochumBochum, Germany; International Graduate School of Neuroscience, Ruhr University BochumBochum, Germany
| | - Bezhad Amanpour-Gharaei
- Department of Neurophysiology, Medical Faculty, Ruhr University BochumBochum, Germany; International Graduate School of Neuroscience, Ruhr University BochumBochum, Germany
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105
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Newman LA, Scavuzzo CJ, Gold PE, Korol DL. Training-induced elevations in extracellular lactate in hippocampus and striatum: Dissociations by cognitive strategy and type of reward. Neurobiol Learn Mem 2017; 137:142-153. [PMID: 27919829 PMCID: PMC5215615 DOI: 10.1016/j.nlm.2016.12.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 10/27/2016] [Accepted: 12/01/2016] [Indexed: 01/05/2023]
Abstract
Recent evidence suggests that astrocytes convert glucose to lactate, which is released from the astrocytes and supports learning and memory. This report takes a multiple memory perspective to test the role of astrocytes in cognition using real-time lactate measurements during learning and memory. Extracellular lactate levels in the hippocampus or striatum were determined with lactate biosensors while rats were learning place (hippocampus-sensitive) or response (striatum-sensitive) versions of T-mazes. In the first experiment, rats were trained on the place and response tasks to locate a food reward. Extracellular lactate levels in the hippocampus increased beyond those of feeding controls during place training but not during response training. However, striatal lactate levels did not increase beyond those of controls when rats were trained on either the place or the response version of the maze. Because food ingestion itself increased blood glucose and brain lactate levels, the contribution of feeding may have confounded the brain lactate measures. Therefore, we conducted a second similar experiment using water as the reward. A very different pattern of lactate responses to training emerged when water was used as the task reward. First, provision of water itself did not result in large increases in either brain or blood lactate levels. Moreover, extracellular lactate levels increased in the striatum during response but not place learning, whereas extracellular lactate levels in the hippocampus did not differ across tasks. The findings from the two experiments suggest that the relative engagement of the hippocampus and striatum dissociates not only by task but also by reward type. The divergent lactate responses of the hippocampus and striatum in place and response tasks under different reward conditions may reflect ethological constraints tied to foraging for food and water.
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Affiliation(s)
- Lori A Newman
- Department of Biology, Syracuse University, Syracuse, NY 13224, USA
| | - Claire J Scavuzzo
- Department of Psychology, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - Paul E Gold
- Department of Biology, Syracuse University, Syracuse, NY 13224, USA
| | - Donna L Korol
- Department of Biology, Syracuse University, Syracuse, NY 13224, USA.
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106
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Wisse LE, Daugherty AM, Olsen RK, Berron D, Carr VA, Stark CE, Amaral RS, Amunts K, Augustinack JC, Bender AR, Bernstein JD, Boccardi M, Bocchetta M, Burggren A, Chakravarty MM, Chupin M, Ekstrom A, de Flores R, Insausti R, Kanel P, Kedo O, Kennedy KM, Kerchner GA, LaRocque KF, Liu X, Maass A, Malykhin N, Mueller SG, Ofen N, Palombo DJ, Parekh MB, Pluta JB, Pruessner JC, Raz N, Rodrigue KM, Schoemaker D, Shafer AT, Steve TA, Suthana N, Wang L, Winterburn JL, Yassa MA, Yushkevich PA, la Joie R. A harmonized segmentation protocol for hippocampal and parahippocampal subregions: Why do we need one and what are the key goals? Hippocampus 2017; 27:3-11. [PMID: 27862600 PMCID: PMC5167633 DOI: 10.1002/hipo.22671] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 10/06/2016] [Accepted: 10/17/2016] [Indexed: 01/08/2023]
Abstract
The advent of high-resolution magnetic resonance imaging (MRI) has enabled in vivo research in a variety of populations and diseases on the structure and function of hippocampal subfields and subdivisions of the parahippocampal gyrus. Because of the many extant and highly discrepant segmentation protocols, comparing results across studies is difficult. To overcome this barrier, the Hippocampal Subfields Group was formed as an international collaboration with the aim of developing a harmonized protocol for manual segmentation of hippocampal and parahippocampal subregions on high-resolution MRI. In this commentary we discuss the goals for this protocol and the associated key challenges involved in its development. These include differences among existing anatomical reference materials, striking the right balance between reliability of measurements and anatomical validity, and the development of a versatile protocol that can be adopted for the study of populations varying in age and health. The commentary outlines these key challenges, as well as the proposed solution of each, with concrete examples from our working plan. Finally, with two examples, we illustrate how the harmonized protocol, once completed, is expected to impact the field by producing measurements that are quantitatively comparable across labs and by facilitating the synthesis of findings across different studies. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Laura E.M. Wisse
- Penn Image Computing and Science Laboratory, Department of Radiology, University of Pennsylvania, Philadelphia, USA
| | - Ana M. Daugherty
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Champaign, USA
| | - Rosanna K. Olsen
- Rotman Research Institute, Baycrest Health Sciences, Toronto, Ontario, Canada
| | - David Berron
- Institute of Cognitive Neurology and Dementia Research, Otto-von-Guericke University, Magdeburg, Germany
| | - Valerie A. Carr
- Department of Psychology, Stanford University, Palo Alto, USA
- Department of Psychology, San Jose State University, San Jose, USA
| | - Craig E.L. Stark
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, USA
| | - Robert S.C. Amaral
- Cerebral Imaging Centre, Douglas Mental Health University Institute, McGill University, Montreal, Canada
- Departments of Psychiatry and Biological and Biomedical Engineering, McGill University, Montreal, Canada
- Integrated Program in Neuroscience, McGill University, Montreal, Canada
| | - Katrin Amunts
- Institute of Neuroscience and Medicine, INM-1, Research Center Jülich, Jülich, Germany
- JARA-BRAIN, Jülich-Aachen Research Alliance, Jülich, Germany
- C. and O. Vogt Institute for Brain Research, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Jean C. Augustinack
- AA Martinos Center for Biomedical Imaging, Department of Radiology, Harvard Medical School, Massachusetts General Hospital, Boston, USA
| | - Andrew R. Bender
- Center for Lifespan Psychology, Max Planck Institute for Human Development, Berlin, Germany
| | - Jeffrey D. Bernstein
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Palo Alto, USA
| | - Marina Boccardi
- LANVIE Laboratory of Neuroimaging of Aging, University of Geneva, Geneva, Switzerland
| | - Martina Bocchetta
- Dementia Research Centre, Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London, UK
| | - Alison Burggren
- Department of Psychiatry and Biobehavioural Sciences, University of California Los Angeles, Los Angeles, USA
| | - M. Mallar Chakravarty
- Cerebral Imaging Centre, Douglas Mental Health University Institute, McGill University, Montreal, Canada
- Departments of Psychiatry and Biological and Biomedical Engineering, McGill University, Montreal, Canada
| | - Marie Chupin
- INSERM, CNRS, UMR-S975, Institut du Cerveau et de la Moelle Epinière (ICM), Paris, France
| | - Arne Ekstrom
- Center for Neuroscience, University of California Davis, Davis, USA
- Department of Psychology, University of California Davis, Davis, USA
| | - Robin de Flores
- INSERM U1077, Université de Caen Normandie, UMR-S1077, Ecole Pratique des Hautes Etudes, Centre Hospitalier Universitaire de Caen, Caen, France
| | - Ricardo Insausti
- Human Neuroanatomy Laboratory and C.R.I.B., School of Medicine, University of Castilla-La Mancha, Albacete, Spain
| | - Prabesh Kanel
- Department of Computer Science, Florida State University, Tallahassee, USA
| | - Olga Kedo
- Institute of Neuroscience and Medicine, INM-1, Research Center Jülich, Jülich, Germany
| | - Kristen M. Kennedy
- Center for Vital Longevity, School of Behavioral and Brain Sciences, University of Texas at Dallas, Dallas, USA
| | - Geoffrey A. Kerchner
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Palo Alto, USA
| | | | - Xiuwen Liu
- Department of Computer Science, Florida State University, Tallahassee, USA
| | - Anne Maass
- School of Public Health and Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, USA
| | - Nicolai Malykhin
- Department of Biomedical Engineering, University of Alberta, Edmonton, Canada
- The Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada
- Department of Psychiatry, University of Alberta, Edmonton, Canada
| | - Susanne G. Mueller
- Department of Radiology, University of California, San Francisco, USA
- Center for Imaging of Neurodegenerative Diseases, San Francisco VA Medical Center, San Francisco, USA
| | - Noa Ofen
- Psychology Department, Wayne State University, Detroit, USA
- Institute of Gerontology, Wayne State University, Detroit, USA
| | | | - Mansi B. Parekh
- Department of Radiology, Stanford University, Palo Alto, USA
| | - John B. Pluta
- Penn Image Computing and Science Laboratory, Department of Radiology, University of Pennsylvania, Philadelphia, USA
| | - Jens C. Pruessner
- McGill Centre for Studies in Aging, Faculty of Medicine, McGill University, Montreal, Canada
- Department of Psychology, McGill University, Montreal, Canada
| | - Naftali Raz
- Psychology Department, Wayne State University, Detroit, USA
- Institute of Gerontology, Wayne State University, Detroit, USA
| | - Karen M. Rodrigue
- Center for Vital Longevity, School of Behavioral and Brain Sciences, University of Texas at Dallas, Dallas, USA
| | - Dorothee Schoemaker
- McGill Centre for Studies in Aging, Faculty of Medicine, McGill University, Montreal, Canada
- Department of Psychology, McGill University, Montreal, Canada
| | - Andrea T. Shafer
- Psychology Department, Wayne State University, Detroit, USA
- Institute of Gerontology, Wayne State University, Detroit, USA
| | - Trevor A. Steve
- Division of Neurology, Department of Medicine, University of Alberta, Edmonton, Canada
| | - Nanthia Suthana
- Department of Psychiatry and Biobehavioural Sciences, University of California Los Angeles, Los Angeles, USA
- Department of Neurosurgery, University of California Los Angeles, Los Angeles, USA
| | - Lei Wang
- Northwestern University Feinberg School of Medicine, Chicago, USA
| | - Julie L. Winterburn
- Cerebral Imaging Centre, Douglas Mental Health University Institute, McGill University, Montreal, Canada
- Departments of Psychiatry and Biological and Biomedical Engineering, McGill University, Montreal, Canada
| | - Michael A. Yassa
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, USA
- Department of Neurology, University of California Irvine, Irvine, USA
| | - Paul A. Yushkevich
- Penn Image Computing and Science Laboratory, Department of Radiology, University of Pennsylvania, Philadelphia, USA
| | - Renaud la Joie
- INSERM U1077, Université de Caen Normandie, UMR-S1077, Ecole Pratique des Hautes Etudes, Centre Hospitalier Universitaire de Caen, Caen, France
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107
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De Shetler NG, Rissman J. Dissociable profiles of generalization/discrimination in the human hippocampus during associative retrieval. Hippocampus 2016; 27:115-121. [PMID: 27863445 DOI: 10.1002/hipo.22684] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 10/24/2016] [Accepted: 11/16/2016] [Indexed: 01/21/2023]
Abstract
When encountering stimuli that vary slightly from previous experiences, neural signals within the CA3 and dentate gyrus (CA3 DG) hippocampal subfields are thought to facilitate mnemonic discrimination, whereas CA1 may be less sensitive to minor stimulus changes, allowing for generalization across similar events. Studies have also posited a critical role for CA1 in the comparison of events to memory-derived expectations, but the degree to which these processes are impacted by explicit retrieval demands is yet unclear. To evaluate extant accounts of hippocampal subfield function, we acquired high-resolution fMRI data as participants performed a task in which famous names were used to cue the retrieval of previously paired images. Although both left CA3 DG and CA1 showed match enhancement effects, responding more to original paired images (targets) than to never-before-seen images (novels), the sensitivity of these subfields to stimulus changes and task demands diverged. CA3 DG showed a goal-independent, yet highly specific, preference for previously encountered stimuli, responding equally strongly to targets and mispaired associates, while showing equally weak responses to close lures and novels. In contrast, recognition signals in CA1 were goal-dependent (i.e., not evoked by mispaired associates), yet accommodating of subtle stimulus differences, such that close lures evoked comparable activity as targets. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Natalie G De Shetler
- Department of Psychology, University of California Los Angeles, Los Angeles, California
| | - Jesse Rissman
- Department of Psychology, University of California Los Angeles, Los Angeles, California.,Department of Psychiatry and Biobehavioral Sciences, University of California Los Angeles, Los Angeles, California.,Brain Research Institute, University of California Los Angeles, Los Angeles, California.,Integrative Center for Learning and Memory, University of California Los Angeles, Los Angeles, California
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108
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Satpute AB, Hanington L, Barrett LF. Novel response patterns during repeated presentation of affective and neutral stimuli. Soc Cogn Affect Neurosci 2016; 11:1919-1932. [PMID: 27928070 PMCID: PMC5141956 DOI: 10.1093/scan/nsw104] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 02/18/2016] [Accepted: 08/03/2016] [Indexed: 11/13/2022] Open
Abstract
Repeated stimulus presentations are commonly used in social and affective neuroimaging tasks, but much remains to be known about how the brain processes such repetitions. Using functional magnetic resonance imaging, we found three groups of brain regions with distinct response patterns during repeated presentations of natural scene images. One group consisted of several limbic, paralimbic, frontoparietal and medial prefrontal areas and showed a habituation-like response across pleasant, unpleasant, and neutral image categories. A second group of occipital and adjacent posterior cortical regions showed a pattern of diminishing responses with repeated presentations of affective images but not for neutral images, and also plateaued to activation levels above baseline for all image categories. A third group involved bilateral frontopolar areas and the precuneus and exhibited a novel, non-monotonic response pattern. Activity was low on the first presentation, peaked upon the second presentation (first repetition) and subsequently diminished. These findings indicate that the transition from novel to increasingly familiar, and also arousing to less arousing, involves a broad array of neural mechanisms alluding to both passive learning and active inference strategies.
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Affiliation(s)
- Ajay B Satpute
- Department of Psychology, Pomona College, Claremont, CA 91711, USA
| | - Lydia Hanington
- Department of Psychology, Northeastern University, Boston, MA 02115, USA
| | - Lisa F Barrett
- Department of Psychology, Northeastern University, Boston, MA 02115, USA
- Department of Psychiatry Harvard Medical School and Massachusetts General Hospital, Boston, MA 02115, USA
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109
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Baker S, Vieweg P, Gao F, Gilboa A, Wolbers T, Black S, Rosenbaum R. The Human Dentate Gyrus Plays a Necessary Role in Discriminating New Memories. Curr Biol 2016; 26:2629-2634. [DOI: 10.1016/j.cub.2016.07.081] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 06/08/2016] [Accepted: 07/28/2016] [Indexed: 12/25/2022]
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110
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Pytte CL. Adult Neurogenesis in the Songbird: Region-Specific Contributions of New Neurons to Behavioral Plasticity and Stability. BRAIN, BEHAVIOR AND EVOLUTION 2016; 87:191-204. [PMID: 27560148 DOI: 10.1159/000447048] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Our understanding of the role of new neurons in learning and encoding new information has been largely based on studies of new neurons in the mammalian dentate gyrus and olfactory bulb - brain regions that may be specialized for learning. Thus the role of new neurons in regions that serve other functions has yet to be fully explored. The song system provides a model for studying new neuron function in brain regions that contribute differently to song learning, song auditory discrimination, and song motor production. These regions subserve learning as well as long-term storage of previously learned information. This review examines the differences between learning-based and activity-based retention of new neurons and explores the potential contributions of new neurons to behavioral stability in the song motor production pathway.
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Affiliation(s)
- Carolyn L Pytte
- Psychology Department, Queens College and The Graduate Center, City University of New York, Flushing, N.Y., USA
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111
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Carrillo-Reid L, Yang W, Bando Y, Peterka DS, Yuste R. Imprinting and recalling cortical ensembles. Science 2016; 353:691-4. [PMID: 27516599 DOI: 10.1126/science.aaf7560] [Citation(s) in RCA: 174] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 07/20/2016] [Indexed: 12/15/2022]
Abstract
Neuronal ensembles are coactive groups of neurons that may represent building blocks of cortical circuits. These ensembles could be formed by Hebbian plasticity, whereby synapses between coactive neurons are strengthened. Here we report that repetitive activation with two-photon optogenetics of neuronal populations from ensembles in the visual cortex of awake mice builds neuronal ensembles that recur spontaneously after being imprinted and do not disrupt preexisting ones. Moreover, imprinted ensembles can be recalled by single- cell stimulation and remain coactive on consecutive days. Our results demonstrate the persistent reconfiguration of cortical circuits by two-photon optogenetics into neuronal ensembles that can perform pattern completion.
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Affiliation(s)
- Luis Carrillo-Reid
- NeuroTechnology Center, Department of Biological Sciences, Columbia University, New York, NY 10027, USA.
| | - Weijian Yang
- NeuroTechnology Center, Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Yuki Bando
- NeuroTechnology Center, Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Darcy S Peterka
- NeuroTechnology Center, Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Rafael Yuste
- NeuroTechnology Center, Department of Biological Sciences, Columbia University, New York, NY 10027, USA.
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112
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Anderson ML, James JR, Kirwan CB. An event-related potential investigation of pattern separation and pattern completion processes. Cogn Neurosci 2016; 8:9-23. [DOI: 10.1080/17588928.2016.1195804] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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113
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Cortical pattern separation and item-specific memory encoding. Neuropsychologia 2016; 85:256-71. [DOI: 10.1016/j.neuropsychologia.2016.03.026] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 03/22/2016] [Accepted: 03/23/2016] [Indexed: 12/22/2022]
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114
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Bao X, Raguet LL, Cole SM, Howard JD, Gottfried J. The role of piriform associative connections in odor categorization. eLife 2016; 5. [PMID: 27130519 PMCID: PMC4884078 DOI: 10.7554/elife.13732] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 04/27/2016] [Indexed: 11/24/2022] Open
Abstract
Distributed neural activity patterns are widely proposed to underlie object identification and categorization in the brain. In the olfactory domain, pattern-based representations of odor objects are encoded in piriform cortex. This region receives both afferent and associative inputs, though their relative contributions to odor perception are poorly understood. Here, we combined a placebo-controlled pharmacological fMRI paradigm with multivariate pattern analyses to test the role of associative connections in sustaining olfactory categorical representations. Administration of baclofen, a GABA(B) agonist known to attenuate piriform associative inputs, interfered with within-category pattern separation in piriform cortex, and the magnitude of this drug-induced change predicted perceptual alterations in fine-odor discrimination performance. Comparatively, baclofen reduced pattern separation between odor categories in orbitofrontal cortex, and impeded within-category generalization in hippocampus. Our findings suggest that odor categorization is a dynamic process concurrently engaging stimulus discrimination and generalization at different stages of olfactory information processing, and highlight the importance of associative networks in maintaining categorical boundaries. DOI:http://dx.doi.org/10.7554/eLife.13732.001 Imagine bringing your groceries home and tucking them into the refrigerator. You’ll probably organize the items by categories: lemons and oranges into the fruit drawer, carrots and cauliflower into the vegetable drawer. Categorization is essential, allowing us to interact with the world in the most efficient way possible. If the differences between objects are not relevant to the task at hand, the brain will group objects together based on their shared properties and develop mental representations of the “categories”. Importantly, we are still aware of the distinctions between objects within the same category. Categories of odor (for example, minty or fruity) are represented in a part of the brain called the olfactory (or piriform) cortex, which receives information from odor cues as well as “top-down” information from other areas of the brain. But how do these top-down pathways influence odor categorization? Bao et al. asked how the brain solves the problem of categorizing odors. For the experiments, human volunteers smelled six familiar odors belonging to three different categories while their brain activity was monitored using a magnetic resonance imaging (fMRI) scanner. Then, half of the participants were given a drug called baclofen that prevents top-down inputs, but not odor cues, from reaching the piriform cortex, while the rest received a placebo. After five days of taking the medication, all of the volunteers had another session of fMRI where they had to categorize the same odors as before. The experiments show that when comparing the fMRI scans before and after the drug treatment, the representations of odors belonging to the same category became more distinct in the piriform cortex in the placebo group. Put differently, as the volunteers were repeatedly exposed to odors of well-known categories, they became better at discriminating individual odors within the same category. However, these changes were disrupted in the group of volunteers that took baclofen. Bao et al.’s findings indicate that this “practice makes perfect” approach to recognizing odors relies on top-down inputs into the piriform cortex. In future work it will be important to study the roles of these inputs in learning new categories of odors, and to investigate whether the mechanisms identified here apply to other sensory information and to more abstract knowledge. DOI:http://dx.doi.org/10.7554/eLife.13732.002
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Affiliation(s)
- Xiaojun Bao
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, United States
| | | | - Sydni M Cole
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, United States
| | - James D Howard
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, United States
| | - Jay Gottfried
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, United States.,Department of Psychology, Northwestern University Weinberg College of Arts and Sciences, Evanston, United States
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115
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Svensson M, Grahm M, Ekstrand J, Höglund P, Johansson M, Tingström A. Effect of electroconvulsive seizures on cognitive flexibility. Hippocampus 2016; 26:899-910. [DOI: 10.1002/hipo.22573] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/01/2016] [Indexed: 12/26/2022]
Affiliation(s)
- Maria Svensson
- Department of Clinical Sciences Lund; Psychiatric Neuromodulation Unit, Lund University; Lund Sweden
| | - Matilda Grahm
- Department of Clinical Sciences Lund; Psychiatric Neuromodulation Unit, Lund University; Lund Sweden
| | - Joakim Ekstrand
- Department of Clinical Sciences Lund; Psychiatric Neuromodulation Unit, Lund University; Lund Sweden
| | - Peter Höglund
- Department of Laboratory Medicine; Division of Clinical Chemistry and Pharmacology, Lund University; Lund Sweden
| | - Mikael Johansson
- Department of Clinical Sciences Lund; Psychiatric Neuromodulation Unit, Lund University; Lund Sweden
- Department of Psychology; Neuropsychology, Lund University; Lund Sweden
| | - Anders Tingström
- Department of Clinical Sciences Lund; Psychiatric Neuromodulation Unit, Lund University; Lund Sweden
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116
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Scharfman HE, Myers CE. Corruption of the dentate gyrus by "dominant" granule cells: Implications for dentate gyrus function in health and disease. Neurobiol Learn Mem 2016; 129:69-82. [PMID: 26391451 PMCID: PMC4792754 DOI: 10.1016/j.nlm.2015.09.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 09/02/2015] [Accepted: 09/06/2015] [Indexed: 12/31/2022]
Abstract
The dentate gyrus (DG) and area CA3 of the hippocampus are highly organized lamellar structures which have been implicated in specific cognitive functions such as pattern separation and pattern completion. Here we describe how the anatomical organization and physiology of the DG and CA3 are consistent with structures that perform pattern separation and completion. We then raise a new idea related to the complex circuitry of the DG and CA3 where CA3 pyramidal cell 'backprojections' play a potentially important role in the sparse firing of granule cells (GCs), considered important in pattern separation. We also propose that GC axons, the mossy fibers, already known for their highly specialized structure, have a dynamic function that imparts variance--'mossy fiber variance'--which is important to pattern separation and completion. Computational modeling is used to show that when a subset of GCs become 'dominant,' one consequence is loss of variance in the activity of mossy fiber axons and a reduction in pattern separation and completion in the model. Empirical data are then provided using an example of 'dominant' GCs--subsets of GCs that develop abnormally and have increased excitability. Notably, these abnormal GCs have been identified in animal models of disease where DG-dependent behaviors are impaired. Together these data provide insight into pattern separation and completion, and suggest that behavioral impairment could arise from dominance of a subset of GCs in the DG-CA3 network.
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Affiliation(s)
- Helen E Scharfman
- The Nathan S. Kline Institute for Psychiatric Research, 140 Old Orangeburg Rd., Orangeburg, NY 10962, United States; Departments of Child & Adolescent Psychiatry, Physiology & Neuroscience, and Psychiatry, New York University Langone Medical Center, United States.
| | - Catherine E Myers
- VA New Jersey Health Care System, VA Medical Center, NeuroBehavioral Research Lab (Mail Stop 15a), 385 Tremont Avenue, East Orange, NJ 07018, United States; Department of Pharmacology, Physiology & Neuroscience, Rutgers-New Jersey Medical School, United States
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117
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Roberts WA, Guitar NA, Marsh HL, MacDonald H. Memory systems in the rat: effects of reward probability, context, and congruency between working and reference memory. Anim Cogn 2016; 19:593-604. [DOI: 10.1007/s10071-016-0964-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 02/02/2016] [Accepted: 02/09/2016] [Indexed: 05/29/2023]
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118
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Kent BA, Hvoslef-Eide M, Saksida LM, Bussey TJ. The representational-hierarchical view of pattern separation: Not just hippocampus, not just space, not just memory? Neurobiol Learn Mem 2016; 129:99-106. [PMID: 26836403 DOI: 10.1016/j.nlm.2016.01.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 01/06/2016] [Accepted: 01/13/2016] [Indexed: 12/29/2022]
Abstract
Pattern separation (PS) has been defined as a process of reducing overlap between similar input patterns to minimize interference amongst stored representations. The present article describes this putative PS process from the "representational-hierarchical" perspective (R-H), which uses a hierarchical continuum instead of a cognitive modular processing framework to describe the organization of the ventral visual perirhinal-hippocampal processing stream. Instead of trying to map psychological constructs onto anatomical modules in the brain, the R-H model suggests that the function of brain regions depends upon what representations they contain. We begin by discussing a main principle of the R-H framework, the resolution of "ambiguity" of lower level representations via the formation of unique conjunctive representations in higher level areas, and how this process is remarkably similar to definitions of PS. Work from several species and experimental approaches suggest that this principle of resolution of ambiguity via conjunctive representations has considerable explanatory power, leads to wide possibilities for experimentation, and also supports some perhaps surprising conclusions.
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Affiliation(s)
- B A Kent
- Department of Medicine, Division of Neurology, University of British Columbia, Vancouver, Canada.
| | - M Hvoslef-Eide
- Department of Psychology, University of Cambridge, Cambridge, UK
| | - L M Saksida
- Department of Psychology, University of Cambridge, Cambridge, UK; The Brain and Mind Institute, Western University, London, ON, Canada; Molecular Medicine Research Group, Robarts Research Institute, Schulich School of Medicine & Dentistry, Western University, London, ON, Canada; Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, Western University, London, ON, Canada; MRC and Wellcome Trust Behavioural and Clinical Neuroscience Institute, University of Cambridge, Downing St, Cambridge CB2 3EB, UK
| | - T J Bussey
- Department of Psychology, University of Cambridge, Cambridge, UK; The Brain and Mind Institute, Western University, London, ON, Canada; Molecular Medicine Research Group, Robarts Research Institute, Schulich School of Medicine & Dentistry, Western University, London, ON, Canada; Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, Western University, London, ON, Canada; MRC and Wellcome Trust Behavioural and Clinical Neuroscience Institute, University of Cambridge, Downing St, Cambridge CB2 3EB, UK
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119
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Liu KY, Gould RL, Coulson MC, Ward EV, Howard RJ. Tests of pattern separation and pattern completion in humans-A systematic review. Hippocampus 2016; 26:705-17. [DOI: 10.1002/hipo.22561] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/08/2015] [Indexed: 12/13/2022]
Affiliation(s)
- Kathy Y. Liu
- Department of Old Age Psychiatry; Institute of Psychiatry, Psychology and Neuroscience, King's College London; London United Kingdom
| | - Rebecca L. Gould
- Department of Old Age Psychiatry; Institute of Psychiatry, Psychology and Neuroscience, King's College London; London United Kingdom
| | - Mark C. Coulson
- Department of Psychology; School of Science and Technology, Middlesex University London; London United Kingdom
| | - Emma V. Ward
- Department of Psychology; School of Science and Technology, Middlesex University London; London United Kingdom
| | - Robert J. Howard
- Department of Old Age Psychiatry; Institute of Psychiatry, Psychology and Neuroscience, King's College London; London United Kingdom
- Division of Psychiatry; University College London; London United Kingdom
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120
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Hersman S, Rodriguez Barrera V, Fanselow M. Assigning Function to Adult-Born Neurons: A Theoretical Framework for Characterizing Neural Manipulation of Learning. Front Syst Neurosci 2016; 9:182. [PMID: 26778981 PMCID: PMC4700131 DOI: 10.3389/fnsys.2015.00182] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 12/07/2015] [Indexed: 12/26/2022] Open
Abstract
Neuroscientists are concerned with neural processes or computations, but these may not be directly observable. In the field of learning, a behavioral procedure is observed to lead to performance outcomes, but differing inferences on underlying internal processes can lead to difficulties in interpreting conflicting results. An example of this challenge is how many functions have been attributed to adult-born granule cells in the dentate gyrus. Some of these functions were suggested by computational models of the properties of these neurons, while others were hypothesized after manipulations of adult-born neurons resulted in changes to behavioral metrics. This review seeks to provide a framework, based in learning theory classification of behavioral procedures, of the processes that may be underlying behavioral results after manipulating procedure and observing performance. We propose that this framework can serve to clarify experimental findings on adult-born neurons as well as other classes of neural manipulations and their effects on behavior.
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Affiliation(s)
- Sarah Hersman
- Department of Psychology, University of California, Los AngelesLos Angeles, CA, USA
| | | | - Michael Fanselow
- Department of Psychology, University of California, Los AngelesLos Angeles, CA, USA
- Department of Psychiatry and Biobehavioral Sciences, University of California, Los AngelesLos Angeles, CA, USA
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121
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Moscovitch M, Cabeza R, Winocur G, Nadel L. Episodic Memory and Beyond: The Hippocampus and Neocortex in Transformation. Annu Rev Psychol 2016; 67:105-34. [PMID: 26726963 PMCID: PMC5060006 DOI: 10.1146/annurev-psych-113011-143733] [Citation(s) in RCA: 560] [Impact Index Per Article: 70.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The last decade has seen dramatic technological and conceptual changes in research on episodic memory and the brain. New technologies, and increased use of more naturalistic observations, have enabled investigators to delve deeply into the structures that mediate episodic memory, particularly the hippocampus, and to track functional and structural interactions among brain regions that support it. Conceptually, episodic memory is increasingly being viewed as subject to lifelong transformations that are reflected in the neural substrates that mediate it. In keeping with this dynamic perspective, research on episodic memory (and the hippocampus) has infiltrated domains, from perception to language and from empathy to problem solving, that were once considered outside its boundaries. Using the component process model as a framework, and focusing on the hippocampus, its subfields, and specialization along its longitudinal axis, along with its interaction with other brain regions, we consider these new developments and their implications for the organization of episodic memory and its contribution to functions in other domains.
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Affiliation(s)
- Morris Moscovitch
- Department of Psychology, University of Toronto, Toronto, Ontario M5S 3G3, Canada;
- Rotman Research Institute, Baycrest Center, Toronto, Ontario, M6A 2E1 Canada
- Department of Psychology, Baycrest Center, Toronto, Ontario M6A 2E1, Canada
| | - Roberto Cabeza
- Center for Cognitive Neuroscience, Duke University, Durham, North Carolina 27708;
| | - Gordon Winocur
- Rotman Research Institute, Baycrest Center, Toronto, Ontario, M6A 2E1 Canada
- Department of Psychology, Trent University, Peterborough, Ontario K9J 7B8, Canada
- Department of Psychiatry, University of Toronto, Toronto, Ontario M5T 1R8, Canada;
| | - Lynn Nadel
- Department of Psychology and Cognitive Science Program, University of Arizona, Tucson, Arizona 85721;
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122
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Kyle CT, Stokes JD, Lieberman JS, Hassan AS, Ekstrom AD. Successful retrieval of competing spatial environments in humans involves hippocampal pattern separation mechanisms. eLife 2015; 4. [PMID: 26613414 PMCID: PMC4733045 DOI: 10.7554/elife.10499] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 11/26/2015] [Indexed: 12/29/2022] Open
Abstract
The rodent hippocampus represents different spatial environments distinctly via changes in the pattern of “place cell” firing. It remains unclear, though, how spatial remapping in rodents relates more generally to human memory. Here participants retrieved four virtual reality environments with repeating or novel landmarks and configurations during high-resolution functional magnetic resonance imaging (fMRI). Both neural decoding performance and neural pattern similarity measures revealed environment-specific hippocampal neural codes. Conversely, an interfering spatial environment did not elicit neural codes specific to that environment, with neural activity patterns instead resembling those of competing environments, an effect linked to lower retrieval performance. We find that orthogonalized neural patterns accompany successful disambiguation of spatial environments while erroneous reinstatement of competing patterns characterized interference errors. These results provide the first evidence for environment-specific neural codes in the human hippocampus, suggesting that pattern separation/completion mechanisms play an important role in how we successfully retrieve memories. DOI:http://dx.doi.org/10.7554/eLife.10499.001 How do we remember the different places that we have visited during our day? Studies of brain activity in rats suggest that each place a rat visits is represented by a different pattern of activity in a region of the brain called hippocampus. However, it is not clear what role this “spatial remapping” plays in the formation of memories in humans. Kyle et al. used a technique called functional magnetic resonance imaging (fMRI) to investigate how our brain represents the different places we’ve visited, and how this is linked to how well we can remember these locations. For the experiments, human volunteers played a video game where they visited four virtual environments in a different order. Later, the volunteers were asked to remember details about the virtual environments they had visited while their brain activity was monitored using fMRI. The experiments show that in order to remember distinct locations – even if they have some features in common – the hippocampus produces patterns of activity that have very little overlap with each other. This process is termed “pattern separation”. Sometimes our memory confuses different locations, which could be due to a failure of the brain to distinguish between the patterns of brain activity that represent these locations. Kyle et al.’s findings provide the first evidence for spatial remapping in the human hippocampus and its importance in forming memories of locations. The next steps are to find out how many different environments our brain might be able to store at the same time, and to identify factors that could aid in our memory for spatial locations. DOI:http://dx.doi.org/10.7554/eLife.10499.002
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Affiliation(s)
- Colin T Kyle
- Center for Neuroscience, University of California, Davis, Davis, United States
| | - Jared D Stokes
- Center for Neuroscience, University of California, Davis, Davis, United States.,Department of Psychology, University of California, Davis, Davis, United States
| | | | - Abdul S Hassan
- Center for Neuroscience, University of California, Davis, Davis, United States
| | - Arne D Ekstrom
- Center for Neuroscience, University of California, Davis, Davis, United States.,Department of Psychology, University of California, Davis, Davis, United States
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123
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Neurocognitive Aging and the Hippocampus across Species. Trends Neurosci 2015; 38:800-812. [PMID: 26607684 DOI: 10.1016/j.tins.2015.10.003] [Citation(s) in RCA: 137] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Revised: 09/27/2015] [Accepted: 10/18/2015] [Indexed: 11/23/2022]
Abstract
There is extensive evidence that aging is associated with impairments in episodic memory. Many of these changes have been ascribed to neurobiological alterations to the hippocampal network and its input pathways. A cross-species consensus is beginning to emerge suggesting that subtle synaptic and functional changes within this network may underlie the majority of age-related memory impairments. In this review we survey convergent data from animal and human studies that have contributed significantly to our understanding of the brain-behavior relationships in this network, particularly in the aging brain. We utilize a cognitive as well as a neurobiological perspective and synthesize data across approaches and species to reach a more detailed understanding of age-related alterations in hippocampal memory function.
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124
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Park H, Yang J, Kim R, Li Y, Lee Y, Lee C, Park J, Lee D, Kim H, Kim E. Mice lacking the PSD-95-interacting E3 ligase, Dorfin/Rnf19a, display reduced adult neurogenesis, enhanced long-term potentiation, and impaired contextual fear conditioning. Sci Rep 2015; 5:16410. [PMID: 26553645 PMCID: PMC4639748 DOI: 10.1038/srep16410] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 10/14/2015] [Indexed: 11/09/2022] Open
Abstract
Protein ubiquitination has a significant influence on diverse aspects of neuronal development and function. Dorfin, also known as Rnf19a, is a RING finger E3 ubiquitin ligase implicated in amyotrophic lateral sclerosis and Parkinson's disease, but its in vivo functions have not been explored. We report here that Dorfin is a novel binding partner of the excitatory postsynaptic scaffolding protein PSD-95. Dorfin-mutant (Dorfin(-/-)) mice show reduced adult neurogenesis and enhanced long-term potentiation in the hippocampal dentate gyrus, but normal long-term potentiation in the CA1 region. Behaviorally, Dorfin(-/-) mice show impaired contextual fear conditioning, but normal levels of cued fear conditioning, fear extinction, spatial learning and memory, object recognition memory, spatial working memory, and pattern separation. Using a proteomic approach, we also identify a number of proteins whose ubiquitination levels are decreased in the Dorfin(-/-) brain. These results suggest that Dorfin may regulate adult neurogenesis, synaptic plasticity, and contextual fear memory.
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Affiliation(s)
- Hanwool Park
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea
| | - Jinhee Yang
- Department of Biological Sciences, KAIST, Daejeon 305-701, Korea
| | - Ryunhee Kim
- Department of Biological Sciences, KAIST, Daejeon 305-701, Korea
| | - Yan Li
- Center for Synaptic Brain Dysfunctions, Institute for Basic Science (IBS), Daejeon 305-701, Korea
| | - Yeunkum Lee
- Center for Synaptic Brain Dysfunctions, Institute for Basic Science (IBS), Daejeon 305-701, Korea
| | - Chungwoo Lee
- Department of Biological Sciences, KAIST, Daejeon 305-701, Korea
| | - Jongil Park
- Department of Biological Sciences, KAIST, Daejeon 305-701, Korea
| | - Dongmin Lee
- Department of Anatomy and Division of Brain Korea 21. Biomedical Science, College of Medicine, Korea University, Seoul 136-704, Korea
| | - Hyun Kim
- Department of Anatomy and Division of Brain Korea 21. Biomedical Science, College of Medicine, Korea University, Seoul 136-704, Korea
| | - Eunjoon Kim
- Department of Biological Sciences, KAIST, Daejeon 305-701, Korea.,Center for Synaptic Brain Dysfunctions, Institute for Basic Science (IBS), Daejeon 305-701, Korea
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125
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Lee JK, Wendelken C, Bunge SA, Ghetti S. A Time and Place for Everything: Developmental Differences in the Building Blocks of Episodic Memory. Child Dev 2015; 87:194-210. [PMID: 26493950 DOI: 10.1111/cdev.12447] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
This research investigated whether episodic memory development can be explained by improvements in relational binding processes, involved in forming novel associations between events and the context in which they occurred. Memory for item-space, item-time, and item-item relations was assessed in an ethnically diverse sample of 151 children aged 7-11 years and 28 young adults. Item-space memory reached adult performance by 9½ years, whereas item-time and item-item memory improved into adulthood. In path analysis, item-space, but not item-time best explained item-item memory. Across age groups, relational binding related to source memory and performance on standardized memory assessments. In conclusion, relational binding development depends on relation type, but relational binding overall supports episodic memory development.
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126
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Carasatorre M, Ochoa-Alvarez A, Velázquez-Campos G, Lozano-Flores C, Ramírez-Amaya V, Díaz-Cintra SY. Hippocampal Synaptic Expansion Induced by Spatial Experience in Rats Correlates with Improved Information Processing in the Hippocampus. PLoS One 2015; 10:e0132676. [PMID: 26244549 PMCID: PMC4526663 DOI: 10.1371/journal.pone.0132676] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 06/18/2015] [Indexed: 12/31/2022] Open
Abstract
Spatial water maze (WM) overtraining induces hippocampal mossy fiber (MF) expansion, and it has been suggested that spatial pattern separation depends on the MF pathway. We hypothesized that WM experience inducing MF expansion in rats would improve spatial pattern separation in the hippocampal network. We first tested this by using the the delayed non-matching to place task (DNMP), in animals that had been previously trained on the water maze (WM) and found that these animals, as well as animals treated as swim controls (SC), performed better than home cage control animals the DNMP task. The "catFISH" imaging method provided neurophysiological evidence that hippocampal pattern separation improved in animals treated as SC, and this improvement was even clearer in animals that experienced the WM training. Moreover, these behavioral treatments also enhance network reliability and improve partial pattern separation in CA1 and pattern completion in CA3. By measuring the area occupied by synaptophysin staining in both the stratum oriens and the stratun lucidum of the distal CA3, we found evidence of structural synaptic plasticity that likely includes MF expansion. Finally, the measures of hippocampal network coding obtained with catFISH correlate significantly with the increased density of synaptophysin staining, strongly suggesting that structural synaptic plasticity in the hippocampus induced by the WM and SC experience is related to the improvement of spatial information processing in the hippocampus.
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Affiliation(s)
- Mariana Carasatorre
- Department of "Neurobiología del Desarrollo y Neurofisiología, Instituto de Neurobiología", Universidad Nacional Autónoma de México, Querétaro, México
| | - Adrian Ochoa-Alvarez
- Department of "Neurobiología del Desarrollo y Neurofisiología, Instituto de Neurobiología", Universidad Nacional Autónoma de México, Querétaro, México
| | - Giovanna Velázquez-Campos
- Department of "Neurobiología Conductual y Cognitiva, Instituto de Neurobiología, Universidad Nacional Autónoma de México", Querétaro, México; Departament of "Microbiología, Maestría en Neurometabolismo & Maestría en Nutrición Humana, Facultad de Ciencias Naturales, Universidad Autónoma de Querétaro, Querétaro, México
| | - Carlos Lozano-Flores
- Department of "Neurobiología del Desarrollo y Neurofisiología, Instituto de Neurobiología", Universidad Nacional Autónoma de México, Querétaro, México
| | - Víctor Ramírez-Amaya
- Department of "Neurobiología del Desarrollo y Neurofisiología, Instituto de Neurobiología", Universidad Nacional Autónoma de México, Querétaro, México
| | - Sofía Y Díaz-Cintra
- Departament of "Microbiología, Maestría en Neurometabolismo & Maestría en Nutrición Humana, Facultad de Ciencias Naturales, Universidad Autónoma de Querétaro, Querétaro, México
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127
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Abstract
The hippocampus has a pivotal role in learning and in the formation and consolidation of memory and is critically involved in the regulation of emotion, fear, anxiety, and stress. Studies of the hippocampus have been central to the study of memory in humans and in recent years, the regional specialization and organization of hippocampal functions have been elucidated in experimental models and in human neurological and psychiatric diseases. The hippocampus has long been considered a classic model for the study of neuroplasticity as many examples of synaptic plasticity such as long-term potentiation and -depression have been identified and demonstrated in hippocampal circuits. Neuroplasticity is the ability to adapt and reorganize the structure or function to internal or external stimuli and occurs at the cellular, population, network or behavioral level and is reflected in the cytological and network architecture as well as in intrinsic properties of hippocampal neurons and circuits. The high degree of hippocampal neuroplasticity might, however, be also negatively reflected in the pronounced vulnerability of the hippocampus to deleterious conditions such as ischemia, epilepsy, chronic stress, neurodegeneration and aging targeting hippocampal structure and function and leading to cognitive deficits. Considering this framework of plasticity and vulnerability, we here review basic principles of hippocampal anatomy and neuroplasticity on various levels as well as recent findings regarding the functional organization of the hippocampus in light of the regional vulnerability in Alzheimer's disease, ischemia, epilepsy, neuroinflammation and aging.
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Affiliation(s)
- T Bartsch
- Department of Neurology, Memory Disorders and Plasticity Group, University Hospital Schleswig-Holstein, Kiel, Germany.
| | - P Wulff
- Institute of Physiology, Neurophysiology, University of Kiel, Olshausenstrasse 40, 24098 Kiel, Germany.
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128
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Leiker EK, Johnson JD. Pattern reactivation co-varies with activity in the core recollection network during source memory. Neuropsychologia 2015; 75:88-98. [DOI: 10.1016/j.neuropsychologia.2015.05.021] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 05/01/2015] [Accepted: 05/21/2015] [Indexed: 01/13/2023]
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129
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Gidyk DC, Deibel SH, Hong NS, McDonald RJ. Barriers to developing a valid rodent model of Alzheimer's disease: from behavioral analysis to etiological mechanisms. Front Neurosci 2015; 9:245. [PMID: 26283893 PMCID: PMC4518326 DOI: 10.3389/fnins.2015.00245] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 06/29/2015] [Indexed: 12/30/2022] Open
Abstract
Sporadic Alzheimer's disease (AD) is the most prevalent form of age-related dementia. As such, great effort has been put forth to investigate the etiology, progression, and underlying mechanisms of the disease. Countless studies have been conducted, however, the details of this disease remain largely unknown. Rodent models provide opportunities to investigate certain aspects of AD that cannot be studied in humans. These animal models vary from study to study and have provided some insight, but no real advancements in the prevention or treatment of the disease. In this Hypothesis and Theory paper, we discuss what we perceive as barriers to impactful discovery in rodent AD research and we offer potential solutions for moving forward. Although no single model of AD is capable of providing the solution to the growing epidemic of the disease, we encourage a comprehensive approach that acknowledges the complex etiology of AD with the goal of enhancing the bidirectional translatability from bench to bedside and vice versa.
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Affiliation(s)
- Darryl C. Gidyk
- *Correspondence: Darryl C. Gidyk, Department of Neuroscience, Canadian Centre for Behavioural Neuroscience, University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 6W4, Canada
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130
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Rolls ET. Pattern separation, completion, and categorisation in the hippocampus and neocortex. Neurobiol Learn Mem 2015; 129:4-28. [PMID: 26190832 DOI: 10.1016/j.nlm.2015.07.008] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 07/02/2015] [Accepted: 07/11/2015] [Indexed: 12/22/2022]
Abstract
The mechanisms for pattern completion and pattern separation are described in the context of a theory of hippocampal function in which the hippocampal CA3 system operates as a single attractor or autoassociation network to enable rapid, one-trial, associations between any spatial location (place in rodents, or spatial view in primates) and an object or reward, and to provide for completion of the whole memory during recall from any part. The factors important in the pattern completion in CA3 and also a large number of independent memories stored in CA3 include: a sparse distributed representation, representations that are independent due to the randomizing effect of the mossy fibres, heterosynaptic long-term depression as well as long-term potentiation in the recurrent collateral synapses, and diluted connectivity to minimize the number of multiple synapses between any pair of CA3 neurons which otherwise distort the basins of attraction. Recall of information from CA3 is implemented by the entorhinal cortex perforant path synapses to CA3 cells, which in acting as a pattern associator allow some pattern generalization. Pattern separation is performed in the dentate granule cells using competitive learning to convert grid-like entorhinal cortex firing to place-like fields, and in the dentate to CA3 connections that have diluted connectivity. Recall to the neocortex is achieved by a reverse hierarchical series of pattern association networks implemented by the hippocampo-cortical backprojections, each one of which performs some pattern generalization, to retrieve a complete pattern of cortical firing in higher-order cortical areas. New results on competitive networks show which factors contribute to their ability to perform pattern separation, pattern clustering, and pattern categorisation, and how these apply in different hippocampal and neocortical systems.
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Affiliation(s)
- Edmund T Rolls
- Oxford Centre for Computational Neuroscience, Oxford, England, United Kingdom; University of Warwick, Department of Computer Science, Coventry CV4 7AL, England, United Kingdom.
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131
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Whitfield JF, Chiarini A, Dal Prà I, Armato U, Chakravarthy B. The Possible Roles of the Dentate Granule Cell's Leptin and Other Ciliary Receptors in Alzheimer's Neuropathology. Cells 2015; 4:253-74. [PMID: 26184316 PMCID: PMC4588035 DOI: 10.3390/cells4030253] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 06/18/2015] [Accepted: 07/06/2015] [Indexed: 12/20/2022] Open
Abstract
Dentate-gyral granule cells in the hippocampus plus dentate gyrus memory-recording/retrieving machine, unlike most other neurons in the brain, are continuously being generated in the adult brain with the important task of separating overlapping patterns of data streaming in from the outside world via the entorhinal cortex. This "adult neurogenesis" is driven by tools in the mature granule cell's cilium. Here we report our discovery of leptin's LepRb receptor in this cilium. In addition, we discuss how ciliary LepRb signaling might be involved with ciliary p75NTR and SSTR3 receptors in adult neurogenesis and memory formation as well as attenuation of Alzheimer's neuropathology by reducing the production of its toxic amyloid-β-derived drivers.
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Affiliation(s)
- James F Whitfield
- Human Health Therapeutics, National Research Council of Canada, Ottawa, ON K1A 0R6, Canada.
| | - Anna Chiarini
- Histology & Embryology Unit, Department of Life & Reproduction Sciences, University of Verona Medical School, 8 Strada Le Grazie, Verona, Venetia 37134, Italy.
| | - Ilaria Dal Prà
- Histology & Embryology Unit, Department of Life & Reproduction Sciences, University of Verona Medical School, 8 Strada Le Grazie, Verona, Venetia 37134, Italy.
| | - Ubaldo Armato
- Histology & Embryology Unit, Department of Life & Reproduction Sciences, University of Verona Medical School, 8 Strada Le Grazie, Verona, Venetia 37134, Italy.
| | - Balu Chakravarthy
- Human Health Therapeutics, National Research Council of Canada, Ottawa, ON K1A 0R6, Canada.
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132
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Trieu BH, Kramár EA, Cox CD, Jia Y, Wang W, Gall CM, Lynch G. Pronounced differences in signal processing and synaptic plasticity between piriform-hippocampal network stages: a prominent role for adenosine. J Physiol 2015; 593:2889-907. [PMID: 25902928 DOI: 10.1113/jp270398] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 04/17/2015] [Indexed: 01/02/2023] Open
Abstract
KEY POINTS Extended trains of theta rhythm afferent activity lead to a biphasic response facilitation in field CA1 but not in the lateral perforant path input to the dentate gyrus. Processes that reverse long-term potentiation in field CA1 are not operative in the lateral perforant path: multiple lines of evidence indicate that this reflects differences in adenosine signalling. Adenosine A1 receptors modulate baseline synaptic transmission in the lateral olfactory tract but not the associational afferents of the piriform cortex. Levels of ecto-5'-nucleotidase (CD73), an enzyme that converts extracellular ATP into adenosine, are markedly different between regions and correlate with adenosine signalling and the efficacy of theta pulse stimulation in reversing long-term potentiation. Variations in transmitter mobilization, CD73 levels, and afferent divergence result in multivariate differences in signal processing through nodes in the cortico-hippocampal network. ABSTRACT The present study evaluated learning-related synaptic operations across the serial stages of the olfactory cortex-hippocampus network. Theta frequency stimulation produced very different time-varying responses in the Schaffer-commissural projections than in the lateral perforant path (LPP), an effect associated with distinctions in transmitter mobilization. Long-term potentiation (LTP) had a higher threshold in LPP field potential studies but not in voltage clamped neurons; coupled with input/output relationships, these results suggest that LTP threshold differences reflect the degree of input divergence. Theta pulse stimulation erased LTP in CA1 but not in the dentate gyrus (DG), although adenosine eliminated potentiation in both areas, suggesting that theta increases extracellular adenosine to a greater degree in CA1. Moreover, adenosine A1 receptor antagonism had larger effects on theta responses in CA1 than in the DG, and concentrations of ecto-5'-nucleotidase (CD73) were much higher in CA1. Input/output curves for two connections in the piriform cortex were similar to those for the LPP, whereas adenosine modulation again correlated with levels of CD73. In sum, multiple relays in a network extending from the piriform cortex through the hippocampus can be differentiated along three dimensions (input divergence, transmitter mobilization, adenosine modulation) that potently influence throughput and plasticity. A model that incorporates the regional differences, supplemented with data for three additional links, suggests that network output goes through three transitions during the processing of theta input. It is proposed that individuated relays allow the circuit to deal with different types of behavioural problems.
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Affiliation(s)
- Brian H Trieu
- Department of Anatomy and Neurobiology, University of California, Irvine, CA, USA
| | - Enikö A Kramár
- Department of Neurobiology and Behavior, University of California, Irvine, CA, USA
| | - Conor D Cox
- Department of Anatomy and Neurobiology, University of California, Irvine, CA, USA
| | - Yousheng Jia
- Department of Anatomy and Neurobiology, University of California, Irvine, CA, USA
| | - Weisheng Wang
- Department of Anatomy and Neurobiology, University of California, Irvine, CA, USA
| | - Christine M Gall
- Department of Anatomy and Neurobiology, University of California, Irvine, CA, USA.,Department of Neurobiology and Behavior, University of California, Irvine, CA, USA
| | - Gary Lynch
- Department of Anatomy and Neurobiology, University of California, Irvine, CA, USA.,Department of Psychiatry and Human Behavior, University of California, Irvine, CA, USA
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133
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Kinnavane L, Albasser MM, Aggleton JP. Advances in the behavioural testing and network imaging of rodent recognition memory. Behav Brain Res 2015; 285:67-78. [PMID: 25106740 PMCID: PMC4383364 DOI: 10.1016/j.bbr.2014.07.049] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 07/23/2014] [Accepted: 07/28/2014] [Indexed: 12/12/2022]
Abstract
Research into object recognition memory has been galvanised by the introduction of spontaneous preference tests for rodents. The standard task, however, contains a number of inherent shortcomings that reduce its power. Particular issues include the problem that individual trials are time consuming, so limiting the total number of trials in any condition. In addition, the spontaneous nature of the behaviour and the variability between test objects add unwanted noise. To combat these issues, the 'bow-tie maze' was introduced. Although still based on the spontaneous preference of novel over familiar stimuli, the ability to give multiple trials within a session without handling the rodents, as well as using the same objects as both novel and familiar samples on different trials, overcomes key limitations in the standard task. Giving multiple trials within a single session also creates new opportunities for functional imaging of object recognition memory. A series of studies are described that examine the expression of the immediate-early gene, c-fos. Object recognition memory is associated with increases in perirhinal cortex and area Te2 c-fos activity. When rats explore novel objects the pathway from the perirhinal cortex to lateral entorhinal cortex, and then to the dentate gyrus and CA3, is engaged. In contrast, when familiar objects are explored the pathway from the perirhinal cortex to lateral entorhinal cortex, and then to CA1, takes precedence. The switch to the perforant pathway (novel stimuli) from the temporoammonic pathway (familiar stimuli) may assist the enhanced associative learning promoted by novel stimuli.
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Affiliation(s)
- Lisa Kinnavane
- School of Psychology, Cardiff University, Tower Building, 70 Park Place, Cardiff, Wales CF10 3AT, United Kingdom.
| | - Mathieu M Albasser
- School of Psychology, Cardiff University, Tower Building, 70 Park Place, Cardiff, Wales CF10 3AT, United Kingdom
| | - John P Aggleton
- School of Psychology, Cardiff University, Tower Building, 70 Park Place, Cardiff, Wales CF10 3AT, United Kingdom
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134
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Lambert FR, Lavenex P, Lavenex PB. Improvement of allocentric spatial memory resolution in children from 2 to 4 years of age. INTERNATIONAL JOURNAL OF BEHAVIORAL DEVELOPMENT 2015. [DOI: 10.1177/0165025415584808] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Allocentric spatial memory, the memory for locations coded in relation to objects comprising our environment, is a fundamental component of episodic memory and is dependent on the integrity of the hippocampal formation in adulthood. Previous research from different laboratories reported that basic allocentric spatial memory abilities are reliably observed in children after 2 years of age. Based on work performed in monkeys and rats, we had proposed that the functional maturation of direct entorhinal cortex projections to the CA1 field of the hippocampus might underlie the emergence of basic allocentric spatial memory. We also proposed that the protracted development of the dentate gyrus and its projections to the CA3 field of the hippocampus might underlie the development of high-resolution allocentric spatial memory capacities, based on the essential contribution of these structures to the process known as pattern separation. Here, we present an experiment designed to assess the development of spatial pattern separation capacities and its impact on allocentric spatial memory performance in children from 18 to 48 months of age. We found that: (1) allocentric spatial memory performance improved with age, (2) as compared to younger children, a greater number of children older than 36 months advanced to the final stage requiring the highest degree of spatial resolution, and (3) children that failed at different stages exhibited difficulties in discriminating locations that required higher spatial resolution abilities. These results are consistent with the hypothesis that improvements in human spatial memory performance might be linked to improvements in pattern separation capacities.
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Affiliation(s)
| | - Pierre Lavenex
- University of Fribourg, Switzerland
- University of Lausanne, Switzerland
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135
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Vieweg P, Stangl M, Howard LR, Wolbers T. Changes in pattern completion--a key mechanism to explain age-related recognition memory deficits? Cortex 2015; 64:343-51. [PMID: 25597525 PMCID: PMC4884644 DOI: 10.1016/j.cortex.2014.12.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 10/29/2014] [Accepted: 12/09/2014] [Indexed: 12/27/2022]
Abstract
Accurate memory retrieval from partial or degraded input requires the reactivation of memory traces, a hippocampal mechanism termed pattern completion. Age-related changes in hippocampal integrity have been hypothesized to shift the balance of memory processes in favor of the retrieval of already stored information (pattern completion), to the detriment of encoding new events (pattern separation). Using a novel behavioral paradigm, we investigated the impact of cognitive aging (1) on recognition performance across different levels of stimulus completeness, and (2) on potential response biases. Participants were required to identify previously learned scenes among new ones. Additionally, all stimuli were presented in gradually masked versions to alter stimulus completeness. Both young and older adults performed increasingly poorly as the scenes became less complete, and this decline in performance was more pronounced in elderly participants indicative of a pattern completion deficit. Intriguingly, when novel scenes were shown, only the older adults showed an increased tendency to identify these as familiar scenes. In line with theoretical models, we argue that this reflects an age-related bias towards pattern completion.
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Affiliation(s)
- Paula Vieweg
- German Center for Neurodegenerative Diseases (DZNE), Aging and Cognition Research Group, Magdeburg, Germany.
| | - Matthias Stangl
- German Center for Neurodegenerative Diseases (DZNE), Aging and Cognition Research Group, Magdeburg, Germany
| | - Lorelei R Howard
- German Center for Neurodegenerative Diseases (DZNE), Aging and Cognition Research Group, Magdeburg, Germany
| | - Thomas Wolbers
- German Center for Neurodegenerative Diseases (DZNE), Aging and Cognition Research Group, Magdeburg, Germany; Center for Behavioral Brain Sciences, Magdeburg, Germany
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136
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van Goethem NP, Schreiber R, Newman-Tancredi A, Varney M, Prickaerts J. Divergent effects of the 'biased' 5-HT1 A receptor agonists F15599 and F13714 in a novel object pattern separation task. Br J Pharmacol 2015; 172:2532-43. [PMID: 25572672 DOI: 10.1111/bph.13071] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 12/04/2014] [Accepted: 12/30/2014] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND AND PURPOSE Pattern separation, that is, the formation of distinct representations from similar inputs, is an important hippocampal process implicated in cognitive domains like episodic memory. A deficit in pattern separation could lead to memory impairments in several psychiatric and neurological disorders. Hence, mechanisms by which pattern separation can be increased are of potential therapeutic interest. EXPERIMENTAL APPROACH 5-HT1A receptors are involved in spatial memory. Herein we tested the 'biased' 5-HT1A receptor agonists F15599, which preferentially activates post-synaptic heteroreceptors, and F13714, which preferentially activates raphe-located autoreceptors, in rats in a novel spatial task assessing pattern separation, the object pattern separation (OPS) task. KEY RESULTS The acetylcholinesterase inhibitor donepezil, which served as a positive control, significantly improved spatial pattern separation at a dose of 1 mg·kg(-1) , p.o. F15599 increased pattern separation at 0.04 mg·kg(-1) , i.p., while F13714 decreased pattern separation at 0.0025 mg·kg(-1) , i.p. The selective 5-HT1A receptor antagonist WAY-100635 (0.63 mg·kg(-1) , s.c.) counteracted the effects of both agonists. These data suggest that acute preferential activation of post-synaptic 5-HT1A heteroreceptors improves spatial pattern separation, whereas acute preferential activation of raphe-located 5-HT1A autoreceptors impairs performance. CONCLUSIONS AND IMPLICATIONS We successfully established and validated a novel, simple and robust OPS task and observed a diverging profile of response with 'biased' 5-HT1A receptor agonists based on their targeting of receptors in distinct brain regions. Our data suggest that the post-synaptic 5-HT1A receptor consists of a potential novel molecular target to improve pattern separation performance.
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Affiliation(s)
- N P van Goethem
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
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137
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Lavenex PB, Bostelmann M, Brandner C, Costanzo F, Fragnière E, Klencklen G, Lavenex P, Menghini D, Vicari S. Allocentric spatial learning and memory deficits in Down syndrome. Front Psychol 2015; 6:62. [PMID: 25762946 PMCID: PMC4329802 DOI: 10.3389/fpsyg.2015.00062] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 01/13/2015] [Indexed: 02/05/2023] Open
Abstract
Studies have shown that persons with Down syndrome (DS) exhibit relatively poor language capacities, and impaired verbal and visuoperceptual memory, whereas their visuospatial memory capacities appear comparatively spared. Individuals with DS recall better where an object was previously seen than what object was previously seen. However, most of the evidence concerning preserved visuospatial memory comes from tabletop or computerized experiments which are biased toward testing egocentric (viewpoint-dependent) spatial representations. Accordingly, allocentric (viewpoint-independent) spatial learning and memory capacities may not be necessary to perform these tasks. Thus, in order to more fully characterize the spatial capacities of individuals with DS, allocentric processes underlying real-world navigation must also be investigated. We tested 20 participants with DS and 16 mental age-matched, typically developing (TD) children in a real-world, allocentric spatial (AS) memory task. During local cue (LC) trials, participants had to locate three rewards marked by local color cues, among 12 locations distributed in a 4 m × 4 m arena. During AS trials, participants had to locate the same three rewards, in absence of LCs, based on their relations to distal environmental cues. All TD participants chose rewarded locations in LC and AS trials at above chance level. In contrast, although all but one of the participants with DS exhibited a preference for the rewarded locations in LC trials, only 50% of participants with DS chose the rewarded locations at above chance level in AS trials. As a group, participants with DS performed worse than TD children on all measures of task performance. These findings demonstrate that individuals with DS are impaired at using an AS representation to learn and remember discrete locations in a controlled environment, suggesting persistent and pervasive deficits in hippocampus-dependent memory in DS.
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Affiliation(s)
- Pamela Banta Lavenex
- Laboratory for Experimental Research on Behavior, Institute of Psychology, University of Lausanne Lausanne, Switzerland
| | - Mathilde Bostelmann
- Laboratory for Experimental Research on Behavior, Institute of Psychology, University of Lausanne Lausanne, Switzerland
| | - Catherine Brandner
- Laboratory for Experimental Research on Behavior, Institute of Psychology, University of Lausanne Lausanne, Switzerland
| | - Floriana Costanzo
- Department of Neuroscience, Bambino Gesù Children's Hospital Rome, Italy
| | - Emilie Fragnière
- Laboratory for Experimental Research on Behavior, Institute of Psychology, University of Lausanne Lausanne, Switzerland
| | - Giuliana Klencklen
- Laboratory for Experimental Research on Behavior, Institute of Psychology, University of Lausanne Lausanne, Switzerland
| | - Pierre Lavenex
- Laboratory for Experimental Research on Behavior, Institute of Psychology, University of Lausanne Lausanne, Switzerland
| | - Deny Menghini
- Department of Neuroscience, Bambino Gesù Children's Hospital Rome, Italy
| | - Stefano Vicari
- Department of Neuroscience, Bambino Gesù Children's Hospital Rome, Italy
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138
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A computational theory of hippocampal function, and tests of the theory: New developments. Neurosci Biobehav Rev 2015; 48:92-147. [DOI: 10.1016/j.neubiorev.2014.11.009] [Citation(s) in RCA: 226] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2014] [Revised: 10/24/2014] [Accepted: 11/12/2014] [Indexed: 01/01/2023]
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139
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Paleja M, Girard TA, Herdman KA, Christensen BK. Two distinct neural networks functionally connected to the human hippocampus during pattern separation tasks. Brain Cogn 2014; 92C:101-111. [DOI: 10.1016/j.bandc.2014.10.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2014] [Revised: 10/20/2014] [Accepted: 10/23/2014] [Indexed: 01/03/2023]
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140
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Roles of human hippocampal subfields in retrieval of spatial and temporal context. Behav Brain Res 2014; 278:549-58. [PMID: 25446813 DOI: 10.1016/j.bbr.2014.10.034] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 10/17/2014] [Accepted: 10/22/2014] [Indexed: 12/25/2022]
Abstract
While numerous studies indicate the involvement of the hippocampus in encoding and retrieval of spatial and temporal context, the neural basis of spatial and temporal processing within the hippocampal circuit remains unclear. We employed a novel paradigm in which participants encoded stores within a spatial layout by visiting them in a specific temporal order. Participants then underwent high-resolution functional magnetic resonance imaging (fMRI) targeting the hippocampus while retrieving details of the spatial or temporal context in alternating blocks. During retrieval, participants made judgments about either near or far intervals within the spatial layout or temporal sequence. Across both near and far intervals, we found that retrieving spatial layout and temporal order information resulted in comparable levels of activation in the hippocampus that was not preferentially localized to a specific subfield. Furthermore, using a multivariate approach called multivariate pattern similarity analysis (MPSA), we found that correct near judgments vs. correct far judgments differed in their patterns of activity for spatial vs. temporal order judgments. Despite these differences in MPSA patterns, we did not find any specific subfields differentially recruited for spatial vs. temporal order retrieval. We discuss our results in terms of their relation to computational models of hippocampal subfield function and suggest mechanisms by which the hippocampus could process space and temporal order without the need for specific contributions from hippocampal subfields.
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141
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Abstract
Episodic memory loss is one of the hallmarks of age-related cognitive decline and a major symptom of Alzheimer's disease. The persistence and strength of memories is determined by modulatory factors such as emotional arousal. Whether emotional memories are preserved with age or if these memories are just as susceptible to loss and forgetting is not well understood. We have recently shown that emotion alters how similar memories are stored using nonoverlapping representations (i.e., pattern separation) in an emotional mnemonic discrimination task. Here, we extend this work to testing young and older adults at 2 time points (immediately after encoding and 24 hr later). Overall, older adults performed worse than young adults, a memory deficit that was not secondary to perceptual or attentional deficits. When tested immediately, older adults were impaired on neutral target recognition but intact on emotional target recognition. We also found that a pattern we previously reported in young adults (reduced emotional compared to neutral discrimination of similar items) was reversed in older adults. When tested after 24 hr, young adults exhibited less forgetting of emotional targets compared to neutral, while older adults exhibited more forgetting of emotional targets. Finally, discrimination of highly similar positive items was preserved in older adults. These results suggest that emotional modulation of memory interacts with age in a complex manner such that the emotion-induced memory trade-off reported in young adults is reversed in older adults. These findings shed light on how emotion and memory interact in the aging brain.
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Affiliation(s)
- Stephanie L. Leal
- Department of Psychological and Brain Sciences, Johns Hopkins University
| | - Michael A. Yassa
- Department of Psychological and Brain Sciences, Johns Hopkins University
- Department of Neurobiology and Behavior, University of California, Irvine
- Center for Neurobiology of Learning and Memory, Neurological Disorders, University of California, Irvine
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine
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142
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Kesner RP, Hui X, Sommer T, Wright C, Barrera VR, Fanselow MS. The role of postnatal neurogenesis in supporting remote memory and spatial metric processing. Hippocampus 2014; 24:1663-71. [PMID: 25112894 DOI: 10.1002/hipo.22346] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/08/2014] [Indexed: 01/15/2023]
Abstract
In this study, we determined the contribution of juvenile neurogenesis to the performance of mice on a remote memory for temporally based association task and in a novelty based spatial pattern separation task. This was accomplished by mating homozygous DNMT1-loxP mice with heterozygous GFAP-Cre mice and comparing Cre+ (no postnatal neurogenesis) to Cre- (wild type) littermate offspring. The results indicate that Cre+ mice are impaired relative to Cre- mice in the remote memory for a temporal based association task and in a novelty based spatial pattern separation task. These results support the temporal integration model of Aimone et al., [(2006) Nat Neurosci 9:723-727] and provide further support for an important role for postnatally born neurons in spatial pattern separation. In contrast, Cre+ mice are not impaired relative to Cre- mice in an object-context recognition task and a spatial location recognition task. These latter data suggest that postnatally derived neurons in the dentate gyrus (DG) do not support all spatial and object recognition functions of the DG.
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Affiliation(s)
- Raymond P Kesner
- Department of Psychology, University of Utah, Salt Lake City, Utah
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143
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Mattson MP. Superior pattern processing is the essence of the evolved human brain. Front Neurosci 2014; 8:265. [PMID: 25202234 PMCID: PMC4141622 DOI: 10.3389/fnins.2014.00265] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 08/05/2014] [Indexed: 01/18/2023] Open
Abstract
Humans have long pondered the nature of their mind/brain and, particularly why its capacities for reasoning, communication and abstract thought are far superior to other species, including closely related anthropoids. This article considers superior pattern processing (SPP) as the fundamental basis of most, if not all, unique features of the human brain including intelligence, language, imagination, invention, and the belief in imaginary entities such as ghosts and gods. SPP involves the electrochemical, neuronal network-based, encoding, integration, and transfer to other individuals of perceived or mentally-fabricated patterns. During human evolution, pattern processing capabilities became increasingly sophisticated as the result of expansion of the cerebral cortex, particularly the prefrontal cortex and regions involved in processing of images. Specific patterns, real or imagined, are reinforced by emotional experiences, indoctrination and even psychedelic drugs. Impaired or dysregulated SPP is fundamental to cognitive and psychiatric disorders. A broader understanding of SPP mechanisms, and their roles in normal and abnormal function of the human brain, may enable the development of interventions that reduce irrational decisions and destructive behaviors.
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Affiliation(s)
- Mark P Mattson
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program Baltimore, MD, USA ; Department of Neuroscience, Johns Hopkins University School of Medicine Baltimore, MD, USA
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144
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Olarte-Sánchez CM, Kinnavane L, Amin E, Aggleton JP. Contrasting networks for recognition memory and recency memory revealed by immediate-early gene imaging in the rat. Behav Neurosci 2014; 128:504-22. [PMID: 24933661 PMCID: PMC4105319 DOI: 10.1037/a0037055] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 03/31/2014] [Accepted: 04/17/2014] [Indexed: 01/08/2023]
Abstract
The expression of the immediate-early gene c-fos was used to compare networks of activity associated with recency memory (temporal order memory) and recognition memory. In Experiment 1, rats were first familiarized with sets of objects and then given pairs of different, familiar objects to explore. For the recency test group, each object in a pair was separated by 110 min in the time between their previous presentations. For the recency control test, each object in a pair was separated by less than a 1 min between their prior presentations. Temporal discrimination of the objects correlated with c-fos activity in the recency test group in several sites, including area Te2, the perirhinal cortex, lateral entorhinal cortex, as well as the dentate gyrus, hippocampal fields CA3 and CA1. For both the test and control conditions, network models were derived using structural equation modeling. The recency test model emphasized serial connections from the perirhinal cortex to lateral entorhinal cortex and then to the CA1 subfield. The recency control condition involved more parallel pathways, but again highlighted CA1 within the hippocampus. Both models contrasted with those derived from tests of object recognition (Experiment 2), because stimulus novelty was associated with pathways from the perirhinal cortex to lateral entorhinal cortex that then involved both the dentate gyrus (and CA3) and CA1 in parallel. The present findings implicate CA1 for the processing of familiar stimuli, including recency discriminations, while the dentate gyrus and CA3 pathways are recruited when the perirhinal cortex signals novel stimuli.
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Affiliation(s)
| | - Lisa Kinnavane
- Neuroscience and Mental Health Research Institute, Cardiff University
| | - Eman Amin
- School of Psychology, Cardiff University
| | - John P Aggleton
- Neuroscience and Mental Health Research Institute, Cardiff University
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145
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Hummos A, Franklin CC, Nair SS. Intrinsic mechanisms stabilize encoding and retrieval circuits differentially in a hippocampal network model. Hippocampus 2014; 24:1430-48. [DOI: 10.1002/hipo.22324] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 06/13/2014] [Accepted: 06/16/2014] [Indexed: 01/09/2023]
Affiliation(s)
- Ali Hummos
- Department of Health Informatics; University of Missouri; Columbia Missouri
- Department of Psychiatry; University of Missouri; Columbia Missouri
| | - Charles C. Franklin
- Department of Electrical & Computer Engineering; University of Missouri; Columbia Missouri
| | - Satish S. Nair
- Department of Electrical & Computer Engineering; University of Missouri; Columbia Missouri
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146
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Roberts JM, Ly M, Murray E, Yassa MA. Temporal discrimination deficits as a function of lag interference in older adults. Hippocampus 2014; 24:1189-96. [PMID: 24811482 DOI: 10.1002/hipo.22303] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/06/2014] [Indexed: 12/23/2022]
Abstract
A vital component of episodic memory is the ability to determine the temporal order of remembered events. Although it has been demonstrated that the hippocampus plays a crucial role in this ability, the details of its contributions are not yet fully understood. One proposed contribution of the hippocampus is the reduction of mnemonic interference through pattern separation. Prior studies have used behavioral paradigms designed to assess this function in the temporal domain by evaluating the ability to determine the order of remembered events as a function of proximity in time. Results from these paradigms in older adults (OA) have been mixed, possibly due to limitations in controlling elapsed time and narrow range of temporal lags. Here, we introduce a novel behavioral paradigm designed to overcome these limitations. We report that OAs are impaired relative to younger adults at moderate and high temporal lags but not at low lags (where performance approached floor). We evaluated OAs' ability to benefit from primacy (enhanced order judgment on the first few items of any given sequence) and found two distinct subgroups: one group was on par with young adults [aged-unimpaired (AU)] and the other group was two standard deviations below the mean of young adults [aged-impaired (AI)]. Temporal discrimination performance in AU adults was consistent with a pattern separation deficit, while performance in AI adults was consistent with a generalized temporal processing deficit. We propose that the task introduced is a sensitive marker for episodic memory deficits with age, and may have diagnostic value for early detection of age-related pathology.
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Affiliation(s)
- Jared M Roberts
- Department of Neurobiology and Behavior, University of California, Irvine, California; Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, Maryland
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147
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Abstract
Adult neurogenesis, a developmental process of generating functionally integrated neurons, occurs throughout life in the hippocampus of the mammalian brain and showcases the highly plastic nature of the mature central nervous system. Significant progress has been made in recent years to decipher how adult neurogenesis contributes to brain functions. Here we review recent findings that inform our understanding of adult hippocampal neurogenesis processes and special properties of adult-born neurons. We further discuss potential roles of adult-born neurons at the circuitry and behavioral levels in cognitive and affective functions and how their dysfunction may contribute to various brain disorders. We end by considering a general model proposing that adult neurogenesis is not a cell-replacement mechanism, but instead maintains a plastic hippocampal neuronal circuit via the continuous addition of immature, new neurons with unique properties and structural plasticity of mature neurons induced by new-neuron integration.
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148
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Lee JK, Ekstrom AD, Ghetti S. Volume of hippocampal subfields and episodic memory in childhood and adolescence. Neuroimage 2014; 94:162-171. [PMID: 24642282 DOI: 10.1016/j.neuroimage.2014.03.019] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Revised: 02/01/2014] [Accepted: 03/08/2014] [Indexed: 12/26/2022] Open
Abstract
Episodic memory critically depends on the hippocampus to bind the features of an experience into memory. Episodic memory develops in childhood and adolescence, and hippocampal changes during this period may contribute to this development. Little is known, however, about how the hippocampus contributes to episodic memory development. The hippocampus is comprised of several cytoarchitectural subfields with functional significance for episodic memory. However, hippocampal subfields have not been assessed in vivo during child development, nor has their relation with episodic memory been assessed during this period. In the present study, high-resolution T2-weighted images of the hippocampus were acquired in 39 children and adolescents aged 8 to 14 years (M=11.30, SD=2.38), and hippocampal subfields were segmented using a protocol previously validated in adult populations. We first validated the method in children and adolescents and examined age-related differences in hippocampal subfields and correlations between subfield volumes and episodic memory. Significant age-related increases in the subfield volume were observed into early adolescence in the right CA3/DG and CA1. The right CA3/DG subfield volumes were positively correlated with accurate episodic memory for item-color relations, and the right CA3/DG and subiculum were negatively correlated with item false alarm rates. Subfield development appears to follow a protracted developmental trajectory, and likely plays a pivotal role in episodic memory development.
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Affiliation(s)
- Joshua K Lee
- Department of Psychology, University of California, Davis, 135 Young Hall, One Shields Avenue, Davis, CA 95616, USA; Center for Mind and Brain, University of California, Davis, 202 Cousteau Place, Davis, CA 95618, USA.
| | - Arne D Ekstrom
- Department of Psychology, University of California, Davis, 135 Young Hall, One Shields Avenue, Davis, CA 95616, USA; Center for Neuroscience, University of California, Davis, 1544 Newton Court, Davis, CA 95618, USA
| | - Simona Ghetti
- Department of Psychology, University of California, Davis, 135 Young Hall, One Shields Avenue, Davis, CA 95616, USA; Center for Mind and Brain, University of California, Davis, 202 Cousteau Place, Davis, CA 95618, USA
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149
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Deuker L, Doeller CF, Fell J, Axmacher N. Human neuroimaging studies on the hippocampal CA3 region - integrating evidence for pattern separation and completion. Front Cell Neurosci 2014; 8:64. [PMID: 24624058 PMCID: PMC3941178 DOI: 10.3389/fncel.2014.00064] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 02/13/2014] [Indexed: 12/29/2022] Open
Abstract
Human functional magnetic resonance imaging (fMRI) studies have long investigated the hippocampus without differentiating between its subfields, even though theoretical models and rodent studies suggest that subfields support different and potentially even opposite functions. The CA3 region of the hippocampus has been ascribed a pivotal role both in initially forming associations during encoding and in reconstructing a memory representation based on partial cues during retrieval. These functions have been related to pattern separation and pattern completion, respectively. In recent years, studies using high-resolution fMRI in humans have begun to separate different hippocampal subregions and identify the role of the CA3 subregion relative to the other subregions. However, some of these findings have been inconsistent with theoretical models and findings from electrophysiology. In this review, we describe selected recent studies and highlight how their results might help to define different processes and functions that are presumably carried out by the CA3 region, in particular regarding the seemingly opposing functions of pattern separation and pattern completion. We also describe how these subfield-specific processes are related to behavioral, functional and structural alterations in patients with mild cognitive impairment and Alzheimer’s disease. We conclude with discussing limitations of functional imaging and briefly outline possible future developments of the field.
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Affiliation(s)
- Lorena Deuker
- Department of Epileptology, University of Bonn Bonn, Germany ; Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Nijmegen, Netherlands
| | - Christian F Doeller
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Nijmegen, Netherlands
| | - Juergen Fell
- Department of Epileptology, University of Bonn Bonn, Germany
| | - Nikolai Axmacher
- Department of Epileptology, University of Bonn Bonn, Germany ; German Center for Neurodegenerative Diseases Bonn, Germany
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150
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Leal SL, Tighe SK, Yassa MA. Asymmetric effects of emotion on mnemonic interference. Neurobiol Learn Mem 2014; 111:41-8. [PMID: 24607286 DOI: 10.1016/j.nlm.2014.02.013] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 02/21/2014] [Accepted: 02/24/2014] [Indexed: 01/11/2023]
Abstract
Emotional experiences can strengthen memories so that they can be used to guide future behavior. Emotional arousal, mediated by the amygdala, is thought to modulate storage by the hippocampus, which may encode unique episodic memories via pattern separation--the process by which similar memories are stored using non-overlapping representations. While prior work has examined mnemonic interference due to similarity and emotional modulation of memory independently, examining the mechanisms by which emotion influences mnemonic interference has not been previously accomplished in humans. To this end, we developed an emotional memory task where emotional content and stimulus similarity were varied to examine the effect of emotion on fine mnemonic discrimination (a putative behavioral correlate of hippocampal pattern separation). When tested immediately after encoding, discrimination was reduced for similar emotional items compared to similar neutral items, consistent with a reduced bias towards pattern separation. After 24h, recognition of emotional target items was preserved compared to neutral items, whereas similar emotional item discrimination was further diminished. This suggests a potential mechanism for the emotional modulation of memory with a selective remembering of gist, as well as a selective forgetting of detail, indicating an emotion-induced reduction in pattern separation. This can potentially increase the effective signal-to-noise ratio in any given situation to promote survival. Furthermore, we found that individuals with depressive symptoms hyper-discriminate negative items, which correlated with their symptom severity. This suggests that utilizing mnemonic discrimination paradigms allows us to tease apart the nuances of disorders with aberrant emotional mnemonic processing.
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Affiliation(s)
- Stephanie L Leal
- Department of Neurobiology and Behavior, University of California, Irvine, United States; Department of Psychological and Brain Sciences, Johns Hopkins University, United States
| | - Sarah K Tighe
- Department of Psychiatry, University of Iowa Carver College of Medicine, United States
| | - Michael A Yassa
- Department of Neurobiology and Behavior, University of California, Irvine, United States; Department of Psychological and Brain Sciences, Johns Hopkins University, United States.
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