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Park S, Ko SY, Frankland PW, Josselyn SA. Comparing behaviours induced by natural memory retrieval and optogenetic reactivation of an engram ensemble in mice. Philos Trans R Soc Lond B Biol Sci 2024; 379:20230227. [PMID: 38853560 DOI: 10.1098/rstb.2023.0227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 04/09/2024] [Indexed: 06/11/2024] Open
Abstract
Memories are thought to be stored within sparse collections of neurons known as engram ensembles. Neurons active during a training episode are allocated to an engram ensemble ('engram neurons'). Memory retrieval is initiated by external sensory or internal cues present at the time of training reactivating engram neurons. Interestingly, optogenetic reactivation of engram ensemble neurons alone in the absence of external sensory cues is sufficient to induce behaviour consistent with memory retrieval in mice. However, there may exist differences between the behaviours induced by natural retrieval cues or artificial engram reactivation. Here, we compared two defensive behaviours (freezing and the syllable structure of ultrasonic vocalizations, USVs) induced by sensory cues present at training (natural memory retrieval) and optogenetic engram ensemble reactivation (artificial memory retrieval) in a threat conditioning paradigm in the same mice. During natural memory recall, we observed a strong positive correlation between freezing levels and distinct USV syllable features (characterized by an unsupervised algorithm, MUPET (Mouse Ultrasonic Profile ExTraction)). Moreover, we observed strikingly similar behavioural profiles in terms of freezing and USV characteristics between natural memory recall and artificial memory recall in the absence of sensory retrieval cues. Although our analysis focused on two behavioural measures of threat memory (freezing and USV characteristics), these results underscore the similarities between threat memory recall triggered naturally and through optogenetic reactivation of engram ensembles. This article is part of a discussion meeting issue 'Long-term potentiation: 50 years on'.
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Affiliation(s)
- Sungmo Park
- Program in Neurosciences and Mental Health, Hospital for Sick Children, 555 University Avenue , Toronto, Ontario M5G 1X8, Canada
| | - Sang Yoon Ko
- Program in Neurosciences and Mental Health, Hospital for Sick Children, 555 University Avenue , Toronto, Ontario M5G 1X8, Canada
- Department of Physiology, University of Toronto , Toronto, Ontario M5G 1X8, Canada
| | - Paul W Frankland
- Program in Neurosciences and Mental Health, Hospital for Sick Children, 555 University Avenue , Toronto, Ontario M5G 1X8, Canada
- Department of Physiology, University of Toronto , Toronto, Ontario M5G 1X8, Canada
- Department of Psychology, University of Toronto , Toronto, Ontario M5G 1X8, Canada
| | - Sheena A Josselyn
- Program in Neurosciences and Mental Health, Hospital for Sick Children, 555 University Avenue , Toronto, Ontario M5G 1X8, Canada
- Department of Physiology, University of Toronto , Toronto, Ontario M5G 1X8, Canada
- Department of Psychology, University of Toronto , Toronto, Ontario M5G 1X8, Canada
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2
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Zhang ZH, Wang B, Peng Y, Xu YW, Li CH, Ning YL, Zhao Y, Shan FB, Zhang B, Yang N, Zhang J, Chen X, Xiong RP, Zhou YG, Li P. Identification of a Hippocampus-to-Zona Incerta Projection involved in Motor Learning. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024:e2307185. [PMID: 38958448 DOI: 10.1002/advs.202307185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 05/19/2024] [Indexed: 07/04/2024]
Abstract
Motor learning (ML), which plays a fundamental role in growth and physical rehabilitation, involves different stages of learning and memory processes through different brain regions. However, the neural mechanisms that underlie ML are not sufficiently understood. Here, a previously unreported neuronal projection from the dorsal hippocampus (dHPC) to the zona incerta (ZI) involved in the regulation of ML behaviors is identified. Using recombinant adeno-associated virus, the projections to the ZI are surprisingly identified as originating from the dorsal dentate gyrus (DG) and CA1 subregions of the dHPC. Furthermore, projection-specific chemogenetic and optogenetic manipulation reveals that the projections from the dorsal CA1 to the ZI play key roles in the acquisition and consolidation of ML behaviors, whereas the projections from the dorsal DG to the ZI mediate the retrieval/retention of ML behaviors. The results reveal new projections from the dorsal DG and dorsal CA1 to the ZI involved in the regulation of ML and provide insight into the stages over which this regulation occurs.
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Affiliation(s)
- Zhuo-Hang Zhang
- The Molecular Biology Center, State Key Laboratory of Trauma, Burn and Combined Injury, Department of Army Occupational Disease, Daping Hospital, Army Medical University (Third Military Medical University), 10 Changjiang Zhilu, Chongqing, 400042, China
- Department of Rehabilitation Medicine, The Second Affiliated Hospital of Chongqing Medical University, 76 Linjiang Road, Yuzhong, Chongqing, 400010, China
| | - Bo Wang
- The Molecular Biology Center, State Key Laboratory of Trauma, Burn and Combined Injury, Department of Army Occupational Disease, Daping Hospital, Army Medical University (Third Military Medical University), 10 Changjiang Zhilu, Chongqing, 400042, China
| | - Yan Peng
- The Molecular Biology Center, State Key Laboratory of Trauma, Burn and Combined Injury, Department of Army Occupational Disease, Daping Hospital, Army Medical University (Third Military Medical University), 10 Changjiang Zhilu, Chongqing, 400042, China
| | - Ya-Wei Xu
- The Molecular Biology Center, State Key Laboratory of Trauma, Burn and Combined Injury, Department of Army Occupational Disease, Daping Hospital, Army Medical University (Third Military Medical University), 10 Changjiang Zhilu, Chongqing, 400042, China
| | - Chang-Hong Li
- The Molecular Biology Center, State Key Laboratory of Trauma, Burn and Combined Injury, Department of Army Occupational Disease, Daping Hospital, Army Medical University (Third Military Medical University), 10 Changjiang Zhilu, Chongqing, 400042, China
| | - Ya-Lei Ning
- The Molecular Biology Center, State Key Laboratory of Trauma, Burn and Combined Injury, Department of Army Occupational Disease, Daping Hospital, Army Medical University (Third Military Medical University), 10 Changjiang Zhilu, Chongqing, 400042, China
| | - Yan Zhao
- The Molecular Biology Center, State Key Laboratory of Trauma, Burn and Combined Injury, Department of Army Occupational Disease, Daping Hospital, Army Medical University (Third Military Medical University), 10 Changjiang Zhilu, Chongqing, 400042, China
| | - Fa-Bo Shan
- The Molecular Biology Center, State Key Laboratory of Trauma, Burn and Combined Injury, Department of Army Occupational Disease, Daping Hospital, Army Medical University (Third Military Medical University), 10 Changjiang Zhilu, Chongqing, 400042, China
| | - Bo Zhang
- The Molecular Biology Center, State Key Laboratory of Trauma, Burn and Combined Injury, Department of Army Occupational Disease, Daping Hospital, Army Medical University (Third Military Medical University), 10 Changjiang Zhilu, Chongqing, 400042, China
| | - Nan Yang
- The Molecular Biology Center, State Key Laboratory of Trauma, Burn and Combined Injury, Department of Army Occupational Disease, Daping Hospital, Army Medical University (Third Military Medical University), 10 Changjiang Zhilu, Chongqing, 400042, China
| | - Jing Zhang
- The Molecular Biology Center, State Key Laboratory of Trauma, Burn and Combined Injury, Department of Army Occupational Disease, Daping Hospital, Army Medical University (Third Military Medical University), 10 Changjiang Zhilu, Chongqing, 400042, China
| | - Xing Chen
- The Molecular Biology Center, State Key Laboratory of Trauma, Burn and Combined Injury, Department of Army Occupational Disease, Daping Hospital, Army Medical University (Third Military Medical University), 10 Changjiang Zhilu, Chongqing, 400042, China
| | - Ren-Ping Xiong
- The Molecular Biology Center, State Key Laboratory of Trauma, Burn and Combined Injury, Department of Army Occupational Disease, Daping Hospital, Army Medical University (Third Military Medical University), 10 Changjiang Zhilu, Chongqing, 400042, China
| | - Yuan-Guo Zhou
- The Molecular Biology Center, State Key Laboratory of Trauma, Burn and Combined Injury, Department of Army Occupational Disease, Daping Hospital, Army Medical University (Third Military Medical University), 10 Changjiang Zhilu, Chongqing, 400042, China
| | - Ping Li
- The Molecular Biology Center, State Key Laboratory of Trauma, Burn and Combined Injury, Department of Army Occupational Disease, Daping Hospital, Army Medical University (Third Military Medical University), 10 Changjiang Zhilu, Chongqing, 400042, China
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3
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Premachandran H, Wilkin J, Arruda-Carvalho M. Minimizing Variability in Developmental Fear Studies in Mice: Toward Improved Replicability in the Field. Curr Protoc 2024; 4:e1040. [PMID: 38713136 DOI: 10.1002/cpz1.1040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
In rodents, the first weeks of postnatal life feature remarkable changes in fear memory acquisition, retention, extinction, and discrimination. Early development is also marked by profound changes in brain circuits underlying fear memory processing, with heightened sensitivity to environmental influences and stress, providing a powerful model to study the intersection between brain structure, function, and the impacts of stress. Nevertheless, difficulties related to breeding and housing young rodents, preweaning manipulations, and potential increased variability within that population pose considerable challenges to developmental fear research. Here we discuss several factors that may promote variability in studies examining fear conditioning in young rodents and provide recommendations to increase replicability. We focus primarily on experimental conditions, design, and analysis of rodent fear data, with an emphasis on mouse studies. The convergence of anatomical, synaptic, physiological, and behavioral changes during early life may increase variability, but careful practice and transparency in reporting may improve rigor and consensus in the field. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC.
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Affiliation(s)
- Hanista Premachandran
- Department of Psychology, University of Toronto Scarborough, Toronto, Ontario, Canada
- These authors contributed equally to this work
| | - Jennifer Wilkin
- Department of Psychology, University of Toronto Scarborough, Toronto, Ontario, Canada
- These authors contributed equally to this work
| | - Maithe Arruda-Carvalho
- Department of Psychology, University of Toronto Scarborough, Toronto, Ontario, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
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4
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Mocle AJ, Ramsaran AI, Jacob AD, Rashid AJ, Luchetti A, Tran LM, Richards BA, Frankland PW, Josselyn SA. Excitability mediates allocation of pre-configured ensembles to a hippocampal engram supporting contextual conditioned threat in mice. Neuron 2024; 112:1487-1497.e6. [PMID: 38447576 PMCID: PMC11065628 DOI: 10.1016/j.neuron.2024.02.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 01/08/2024] [Accepted: 02/05/2024] [Indexed: 03/08/2024]
Abstract
Little is understood about how engrams, sparse groups of neurons that store memories, are formed endogenously. Here, we combined calcium imaging, activity tagging, and optogenetics to examine the role of neuronal excitability and pre-existing functional connectivity on the allocation of mouse cornu ammonis area 1 (CA1) hippocampal neurons to an engram ensemble supporting a contextual threat memory. Engram neurons (high activity during recall or TRAP2-tagged during training) were more active than non-engram neurons 3 h (but not 24 h to 5 days) before training. Consistent with this, optogenetically inhibiting scFLARE2-tagged neurons active in homecage 3 h, but not 24 h, before conditioning disrupted memory retrieval, indicating that neurons with higher pre-training excitability were allocated to the engram. We also observed stable pre-configured functionally connected sub-ensembles of neurons whose activity cycled over days. Sub-ensembles that were more active before training were allocated to the engram, and their functional connectivity increased at training. Therefore, both neuronal excitability and pre-configured functional connectivity mediate allocation to an engram ensemble.
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Affiliation(s)
- Andrew J Mocle
- Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Ave., Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5G 1X8, Canada
| | - Adam I Ramsaran
- Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Ave., Toronto, ON M5G 1X8, Canada; Department of Psychology, University of Toronto, Toronto, ON M5G 1X8, Canada
| | - Alexander D Jacob
- Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Ave., Toronto, ON M5G 1X8, Canada; Department of Psychology, University of Toronto, Toronto, ON M5G 1X8, Canada
| | - Asim J Rashid
- Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Ave., Toronto, ON M5G 1X8, Canada
| | - Alessandro Luchetti
- Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Ave., Toronto, ON M5G 1X8, Canada
| | - Lina M Tran
- Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Ave., Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5G 1X8, Canada; Vector Institute, Toronto, ON M5G 1M1, Canada
| | | | - Paul W Frankland
- Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Ave., Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5G 1X8, Canada; Department of Psychology, University of Toronto, Toronto, ON M5G 1X8, Canada; Child & Brain Development Program, Canadian Institute for Advanced Research (CIFAR), Toronto, ON M5G 1M1, Canada
| | - Sheena A Josselyn
- Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Ave., Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5G 1X8, Canada; Department of Psychology, University of Toronto, Toronto, ON M5G 1X8, Canada.
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5
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Bevandić J, Chareyron LJ, Bachevalier J, Cacucci F, Genzel L, Newcombe NS, Vargha-Khadem F, Ólafsdóttir HF. Episodic memory development: Bridging animal and human research. Neuron 2024; 112:1060-1080. [PMID: 38359826 PMCID: PMC11129319 DOI: 10.1016/j.neuron.2024.01.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 12/22/2023] [Accepted: 01/19/2024] [Indexed: 02/17/2024]
Abstract
Human episodic memory is not functionally evident until about 2 years of age and continues to develop into the school years. Behavioral studies have elucidated this developmental timeline and its constituent processes. In tandem, lesion and neurophysiological studies in non-human primates and rodents have identified key neural substrates and circuit mechanisms that may underlie episodic memory development. Despite this progress, collaborative efforts between psychologists and neuroscientists remain limited, hindering progress. Here, we seek to bridge human and non-human episodic memory development research by offering a comparative review of studies using humans, non-human primates, and rodents. We highlight critical theoretical and methodological issues that limit cross-fertilization and propose a common research framework, adaptable to different species, that may facilitate cross-species research endeavors.
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Affiliation(s)
- Juraj Bevandić
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, the Netherlands
| | - Loïc J Chareyron
- Cognitive Neuroscience and Neuropsychiatry, Developmental Neurosciences, University College London Great Ormond Street Institute of Child Health, London, UK; Laboratory of Brain and Cognitive Development, Institute of Psychology, University of Lausanne, Lausanne, Switzerland
| | - Jocelyne Bachevalier
- Division of Developmental and Cognitive Neuroscience, Emory National Primate Research Center, Department of Psychology, Emory University, Atlanta, GA, USA.
| | - Francesca Cacucci
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK.
| | - Lisa Genzel
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, the Netherlands.
| | - Nora S Newcombe
- Department of Psychology, Temple University, Philadelphia, PA, USA.
| | - Faraneh Vargha-Khadem
- Cognitive Neuroscience and Neuropsychiatry, Developmental Neurosciences, University College London Great Ormond Street Institute of Child Health, London, UK.
| | - H Freyja Ólafsdóttir
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, the Netherlands.
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6
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Contreras MP, Mendez M, Shan X, Fechner J, Sawangjit A, Born J, Inostroza M. Context memory formed in medial prefrontal cortex during infancy enhances learning in adulthood. Nat Commun 2024; 15:2475. [PMID: 38509099 PMCID: PMC10954687 DOI: 10.1038/s41467-024-46734-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 03/06/2024] [Indexed: 03/22/2024] Open
Abstract
Adult behavior is commonly thought to be shaped by early-life experience, although episodes experienced during infancy appear to be forgotten. Exposing male rats during infancy to discrete spatial experience we show that these rats in adulthood are significantly better at forming a spatial memory than control rats without such infantile experience. We moreover show that the adult rats' improved spatial memory capability is mainly based on memory for context information during the infantile experiences. Infantile spatial experience increased c-Fos activity at memory testing during adulthood in the prelimbic medial prefrontal cortex (mPFC), but not in the hippocampus. Inhibiting prelimbic mPFC at testing during adulthood abolished the enhancing effect of infantile spatial experience on learning. Adult spatial memory capability only benefitted from spatial experience occurring during the sensitive period of infancy, but not when occurring later during childhood, and when sleep followed the infantile experience. In conclusion, the infantile brain, by a sleep-dependent mechanism, favors consolidation of memory for the context in which episodes are experienced. These representations comprise mPFC regions and context-dependently facilitate learning in adulthood.
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Affiliation(s)
- María P Contreras
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany
- Graduate School of Neural & Behavioral Science, International Max Planck Research School, Tübingen, Germany
- Leibniz-Institute of Neurobiology, Magdeburg, Germany
| | - Marta Mendez
- Laboratory of Neuroscience, Department of Psychology, Instituto de Neurociencias del Principado de Asturias (INEUROPA), University of Oviedo, Plaza Feijoo, Oviedo, Spain
| | - Xia Shan
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany
- Graduate School of Neural & Behavioral Science, International Max Planck Research School, Tübingen, Germany
| | - Julia Fechner
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany
- Graduate School of Neural & Behavioral Science, International Max Planck Research School, Tübingen, Germany
| | - Anuck Sawangjit
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany
| | - Jan Born
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany.
- Werner Reichert Center for Integrative Neuroscience, University of Tübingen, Tübingen, Germany.
- German Center for Diabetes Research (DZD)-Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich (IDM) at the University Tübingen, Tübingen, Germany.
| | - Marion Inostroza
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany.
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7
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Naffaa MM. Significance of the anterior cingulate cortex in neurogenesis plasticity: Connections, functions, and disorders across postnatal and adult stages. Bioessays 2024; 46:e2300160. [PMID: 38135889 DOI: 10.1002/bies.202300160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 12/12/2023] [Accepted: 12/14/2023] [Indexed: 12/24/2023]
Abstract
The anterior cingulate cortex (ACC) is a complex and continually evolving brain region that remains a primary focus of research due to its multifaceted functions. Various studies and analyses have significantly advanced our understanding of how the ACC participates in a wide spectrum of memory and cognitive processes. However, despite its strong connections to brain areas associated with hippocampal and olfactory neurogenesis, the functions of the ACC in regulating postnatal and adult neurogenesis in these regions are still insufficiently explored. Investigating the intricate involvement of the ACC in neurogenesis could enhance our comprehension of essential aspects of brain plasticity. This involvement stems from its complex circuitry with other relevant brain regions, thereby exerting both direct and indirect impacts on the neurogenesis process. This review sheds light on the promising significance of the ACC in orchestrating postnatal and adult neurogenesis in conditions related to memory, cognitive behavior, and associated disorders.
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Affiliation(s)
- Moawiah M Naffaa
- Department of Psychology and Neuroscience, Duke University, Durham, North Carolina, USA
- Department of Cell Biology, Duke University School of Medicine, Durham, North Carolina, USA
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8
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Jin B, Gongwer MW, Ohanian L, Holden-Wingate L, Le B, Darmawan A, Nakayama Y, Rueda Mora SA, DeNardo LA. A developmental brain-wide screen identifies retrosplenial cortex as a key player in the emergence of persistent memory. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.07.574554. [PMID: 38260633 PMCID: PMC10802387 DOI: 10.1101/2024.01.07.574554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Memories formed early in life are short-lived while those formed later persist. Recent work revealed that infant memories are stored in a latent state. But why they fail to be retrieved is poorly understood. Here we investigated brain-wide circuit mechanisms underlying infantile amnesia in mice. We performed a screen that combined activity-dependent neuronal tagging at different postnatal ages, tissue clearing and light sheet microscopy. We observed striking developmental transitions in the organization of fear memory networks and changes in the activity and functional connectivity of the retrosplenial cortex (RSP) that aligned with the emergence of persistent memory. 7 days after learning, chemogenetic reactivation of tagged RSP ensembles enhanced memory in adults but not in infants. But after 33 days, reactivating infant-tagged RSP ensembles recovered forgotten memories. These studies show that RSP ensembles store latent infant memories, reveal the time course of RSP functional maturation, and suggest that immature RSP functional networks contribute to infantile amnesia.
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9
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Ortega-de San Luis C, Pezzoli M, Urrieta E, Ryan TJ. Engram cell connectivity as a mechanism for information encoding and memory function. Curr Biol 2023; 33:5368-5380.e5. [PMID: 37992719 DOI: 10.1016/j.cub.2023.10.074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 09/18/2023] [Accepted: 10/31/2023] [Indexed: 11/24/2023]
Abstract
Information derived from experiences is incorporated into the brain as changes to ensembles of cells, termed engram cells, which allow memory storage and recall. The mechanism by which those changes hold specific information is unclear. Here, we test the hypothesis that the specific synaptic wiring between engram cells is the substrate of information storage. First, we monitor how learning modifies the connectivity pattern between engram cells at a monosynaptic connection involving the hippocampal ventral CA1 (vCA1) region and the amygdala. Then, we assess the functional significance of these connectivity changes by artificially activating or inhibiting its presynaptic and postsynaptic components, respectively. Finally, we identify a synaptic plasticity mechanism mediated by postsynaptic density protein 95 (PSD-95), which impacts the connectivity pattern among engram cells and contributes to the long-term stability of the memory. These findings impact our theory of learning and memory by helping us explain the translation of specific information into engram cells and how these connections shape brain function.
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Affiliation(s)
- Clara Ortega-de San Luis
- School of Biochemistry and Immunology, Trinity College of Dublin, Dublin D02 PN40, Ireland; Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin D02 PN40, Ireland
| | - Maurizio Pezzoli
- School of Biochemistry and Immunology, Trinity College of Dublin, Dublin D02 PN40, Ireland; Brain Mind Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne 1015, Switzerland
| | - Esteban Urrieta
- School of Biochemistry and Immunology, Trinity College of Dublin, Dublin D02 PN40, Ireland; Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin D02 PN40, Ireland
| | - Tomás J Ryan
- School of Biochemistry and Immunology, Trinity College of Dublin, Dublin D02 PN40, Ireland; Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin D02 PN40, Ireland; Florey Institute of Neuroscience and Mental Health, Melbourne Brain Centre, University of Melbourne, Melbourne, VIC 3052, Australia; Child & Brain Development Program, Canadian Institute for Advanced Research (CIFAR), Toronto, ON M5G 1M1, Canada.
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10
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Power SD, Stewart E, Zielke LG, Byrne EP, Douglas A, Ortega-de San Luis C, Lynch L, Ryan TJ. Immune activation state modulates infant engram expression across development. SCIENCE ADVANCES 2023; 9:eadg9921. [PMID: 37939176 PMCID: PMC10631722 DOI: 10.1126/sciadv.adg9921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 10/06/2023] [Indexed: 11/10/2023]
Abstract
Infantile amnesia is possibly the most ubiquitous form of memory loss in mammals. We investigated how memories are stored in the brain throughout development by integrating engram labeling technology with mouse models of infantile amnesia. Here, we found a phenomenon in which male offspring in maternal immune activation models of autism spectrum disorder do not experience infantile amnesia. Maternal immune activation altered engram ensemble size and dendritic spine plasticity. We rescued the same apparently forgotten infantile memories in neurotypical mice by optogenetically reactivating dentate gyrus engram cells labeled during complex experiences in infancy. Furthermore, we permanently reinstated lost infantile memories by artificially updating the memory engram, demonstrating that infantile amnesia is a reversible process. Our findings suggest not only that infantile amnesia is due to a reversible retrieval deficit in engram expression but also that immune activation during development modulates innate, and reversible, forgetting switches that determine whether infantile amnesia will occur.
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Affiliation(s)
- Sarah D. Power
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin, Ireland
- Trinity College Institute for Neuroscience, Trinity College Dublin, Dublin, Ireland
- Center for Lifespan Psychology, Max Planck Institute for Human Development, Berlin, Germany
| | - Erika Stewart
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin, Ireland
- Trinity College Institute for Neuroscience, Trinity College Dublin, Dublin, Ireland
| | - Louisa G. Zielke
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin, Ireland
- Trinity College Institute for Neuroscience, Trinity College Dublin, Dublin, Ireland
- Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, Netherlands
| | - Eric P. Byrne
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin, Ireland
| | - Aaron Douglas
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin, Ireland
- Trinity College Institute for Neuroscience, Trinity College Dublin, Dublin, Ireland
| | - Clara Ortega-de San Luis
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin, Ireland
- Trinity College Institute for Neuroscience, Trinity College Dublin, Dublin, Ireland
| | - Lydia Lynch
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin, Ireland
- Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Tomás J. Ryan
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin, Ireland
- Trinity College Institute for Neuroscience, Trinity College Dublin, Dublin, Ireland
- Florey Institute of Neuroscience and Mental Health, Melbourne Brain Centre, University of Melbourne, Melbourne, VIC, Australia
- Child & Brain Development Program, Canadian Institute for Advanced Research (CIFAR), Toronto, ON, Canada
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11
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Luis CODS, Pezzoli M, Urrieta E, Ryan TJ. Engram cell connectivity as a mechanism for information encoding and memory function. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.21.558774. [PMID: 37790352 PMCID: PMC10542553 DOI: 10.1101/2023.09.21.558774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
Information derived from experiences is incorporated into the brain as changes to ensembles of cells, termed engram cells, that allow memory storage and recall. The mechanism by which those changes hold specific information is unclear. Here we test the hypothesis that the specific synaptic wiring between engram cells is the substrate of information storage. First, we monitor how learning modifies the connectivity pattern between engram cells at a monosynaptic connection involving the hippocampal vCA1 region and the amygdala. Then, we assess the functional significance of these connectivity changes by artificially activating or inhibiting its presynaptic and postsynaptic components respectively. Finally, we identify a synaptic plasticity mechanism mediated by PSD-95, which impacts the connectivity pattern among engram cells and contributes to the long-term stability of the memory. These findings impact our theory of learning and memory by helping us explain the translation of specific information into engram cells and how these connections shape brain function.
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Affiliation(s)
- Clara Ortega-de San Luis
- School of Biochemistry and Immunology, Trinity College of Dublin, Dublin, Ireland
- Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland
| | - Maurizio Pezzoli
- School of Biochemistry and Immunology, Trinity College of Dublin, Dublin, Ireland
- Brain Mind Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Switzerland
| | - Esteban Urrieta
- School of Biochemistry and Immunology, Trinity College of Dublin, Dublin, Ireland
- Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland
| | - Tomás J Ryan
- School of Biochemistry and Immunology, Trinity College of Dublin, Dublin, Ireland
- Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland
- Florey Institute of Neuroscience and Mental Health, Melbourne Brain Centre, University of Melbourne, Melbourne, Victoria, Australia
- Child & Brain Development Program, Canadian Institute for Advanced Research (CIFAR), Toronto, Ontario, Canada
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12
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Autore L, O'Leary JD, Ortega-de San Luis C, Ryan TJ. Adaptive expression of engrams by retroactive interference. Cell Rep 2023; 42:112999. [PMID: 37590145 DOI: 10.1016/j.celrep.2023.112999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 06/17/2023] [Accepted: 08/01/2023] [Indexed: 08/19/2023] Open
Abstract
Long-term memories are stored as configurations of neuronal ensembles, termed engrams. Although investigation of engram cell properties and functionality in memory recall has been extensive, less is known about how engram cells are affected by forgetting. We describe a form of interference-based forgetting using an object memory behavioral paradigm. By using activity-dependent cell labeling, we show that although retroactive interference results in decreased engram cell reactivation during recall trials, optogenetic stimulation of the labeled engram cells is sufficient to induce memory retrieval. Forgotten engrams may be reinstated via the presentation of similar or related environmental information. Furthermore, we demonstrate that engram activity is necessary for interference to occur. Taken together, these findings indicate that retroactive interference modules engram expression in a manner that is both reversible and updatable. Inference may constitute a form of adaptive forgetting where, in everyday life, new perceptual and environmental inputs modulate the natural forgetting process.
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Affiliation(s)
- Livia Autore
- School of Biochemistry and Immunology, Trinity College of Dublin, Dublin, Ireland; Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland
| | - James D O'Leary
- School of Biochemistry and Immunology, Trinity College of Dublin, Dublin, Ireland; Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland
| | - Clara Ortega-de San Luis
- School of Biochemistry and Immunology, Trinity College of Dublin, Dublin, Ireland; Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland
| | - Tomás J Ryan
- School of Biochemistry and Immunology, Trinity College of Dublin, Dublin, Ireland; Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland; Florey Institute of Neuroscience and Mental Health, Melbourne Brain Centre, University of Melbourne, Melbourne, VIC, Australia; Child & Brain Development Program, Canadian Institute for Advanced Research (CIFAR), Toronto, ON, Canada.
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13
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Guskjolen A, Cembrowski MS. Engram neurons: Encoding, consolidation, retrieval, and forgetting of memory. Mol Psychiatry 2023; 28:3207-3219. [PMID: 37369721 PMCID: PMC10618102 DOI: 10.1038/s41380-023-02137-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 06/02/2023] [Accepted: 06/13/2023] [Indexed: 06/29/2023]
Abstract
Tremendous strides have been made in our understanding of the neurobiological substrates of memory - the so-called memory "engram". Here, we integrate recent progress in the engram field to illustrate how engram neurons transform across the "lifespan" of a memory - from initial memory encoding, to consolidation and retrieval, and ultimately to forgetting. To do so, we first describe how cell-intrinsic properties shape the initial emergence of the engram at memory encoding. Second, we highlight how these encoding neurons preferentially participate in synaptic- and systems-level consolidation of memory. Third, we describe how these changes during encoding and consolidation guide neural reactivation during retrieval, and facilitate memory recall. Fourth, we describe neurobiological mechanisms of forgetting, and how these mechanisms can counteract engram properties established during memory encoding, consolidation, and retrieval. Motivated by recent experimental results across these four sections, we conclude by proposing some conceptual extensions to the traditional view of the engram, including broadening the view of cell-type participation within engrams and across memory stages. In collection, our review synthesizes general principles of the engram across memory stages, and describes future avenues to further understand the dynamic engram.
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Affiliation(s)
- Axel Guskjolen
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada.
| | - Mark S Cembrowski
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada.
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada.
- School of Biomedical Engineering, University of British Columbia, Vancouver, BC, Canada.
- Department of Mathematics, University of British Columbia, Vancouver, BC, Canada.
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14
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Borzello M, Ramirez S, Treves A, Lee I, Scharfman H, Stark C, Knierim JJ, Rangel LM. Assessments of dentate gyrus function: discoveries and debates. Nat Rev Neurosci 2023; 24:502-517. [PMID: 37316588 PMCID: PMC10529488 DOI: 10.1038/s41583-023-00710-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/28/2023] [Indexed: 06/16/2023]
Abstract
There has been considerable speculation regarding the function of the dentate gyrus (DG) - a subregion of the mammalian hippocampus - in learning and memory. In this Perspective article, we compare leading theories of DG function. We note that these theories all critically rely on the generation of distinct patterns of activity in the region to signal differences between experiences and to reduce interference between memories. However, these theories are divided by the roles they attribute to the DG during learning and recall and by the contributions they ascribe to specific inputs or cell types within the DG. These differences influence the information that the DG is thought to impart to downstream structures. We work towards a holistic view of the role of DG in learning and memory by first developing three critical questions to foster a dialogue between the leading theories. We then evaluate the extent to which previous studies address our questions, highlight remaining areas of conflict, and suggest future experiments to bridge these theories.
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Affiliation(s)
- Mia Borzello
- Department of Cognitive Science, University of California, San Diego, La Jolla, CA, USA
| | - Steve Ramirez
- Department of Psychological and Brain Sciences, Boston University, Boston, MA, USA
| | | | - Inah Lee
- Department of Brain and Cognitive Sciences, Seoul National University, Seoul, South Korea
| | - Helen Scharfman
- Departments of Child and Adolescent Psychiatry, Neuroscience and Physiology and Psychiatry and the Neuroscience Institute, New York University Langone Health, New York, NY, USA
- The Nathan Kline Institute for Psychiatric Research, Orangeburg, NY, USA
| | - Craig Stark
- Department of Neurobiology and Behaviour, University of California, Irvine, Irvine, CA, USA
| | - James J Knierim
- Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, MD, USA
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD, USA
| | - Lara M Rangel
- Department of Cognitive Science, University of California, San Diego, La Jolla, CA, USA.
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15
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Terranova JI, Yokose J, Osanai H, Ogawa SK, Kitamura T. Systems consolidation induces multiple memory engrams for a flexible recall strategy in observational fear memory in male mice. Nat Commun 2023; 14:3976. [PMID: 37407567 DOI: 10.1038/s41467-023-39718-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 06/20/2023] [Indexed: 07/07/2023] Open
Abstract
Observers learn to fear the context in which they witnessed a demonstrator's aversive experience, called observational contextual fear conditioning (CFC). The neural mechanisms governing whether recall of the observational CFC memory occurs from the observer's own or from the demonstrator's point of view remain unclear. Here, we show in male mice that recent observational CFC memory is recalled in the observer's context only, but remote memory is recalled in both observer and demonstrator contexts. Recall of recent memory in the observer's context requires dorsal hippocampus activity, while recall of remote memory in both contexts requires the medial prefrontal cortex (mPFC)-basolateral amygdala pathway. Although mPFC neurons activated by observational CFC are involved in remote recall in both contexts, distinct mPFC subpopulations regulate remote recall in each context. Our data provide insights into a flexible recall strategy and the functional reorganization of circuits and memory engram cells underlying observational CFC memory.
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Affiliation(s)
- Joseph I Terranova
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
- Department of Anatomy, Midwestern University, Downers Grove, IL, 60615, USA
| | - Jun Yokose
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Hisayuki Osanai
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Sachie K Ogawa
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Takashi Kitamura
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
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16
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Teng SW, Wang XR, Du BW, Chen XL, Fu GZ, Liu YF, Xu SQ, Shuai JC, Chen ZY. Altered fear engram encoding underlying conditioned versus unconditioned stimulus-initiated memory updating. SCIENCE ADVANCES 2023; 9:eadf0284. [PMID: 37285430 DOI: 10.1126/sciadv.adf0284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 05/03/2023] [Indexed: 06/09/2023]
Abstract
It is known that post-retrieval extinction but not extinction alone could erase fear memory. However, whether the coding pattern of original fear engrams is remodeled or inhibited remains largely unclear. We found increased reactivation of engram cells in the prelimbic cortex and basolateral amygdala during memory updating. Moreover, conditioned stimulus- and unconditioned stimulus-initiated memory updating depends on the engram cell reactivation in the prelimbic cortex and basolateral amygdala, respectively. Last, we found that memory updating causes increased overlapping between fear and extinction cells, and the original fear engram encoding was altered during memory updating. Our data provide the first evidence to show the overlapping ensembles between fear and extinction cells and the functional reorganization of original engrams underlying conditioned stimulus- and unconditioned stimulus-initiated memory updating.
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Affiliation(s)
- Shuai-Wen Teng
- Department of Anatomy and Neurobiology, Shandong Provincial Key Laboratory of Mental Disorders, School of Basic Medical Sciences and Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, P.R. China
| | - Xin-Rong Wang
- Department of Anatomy and Neurobiology, Shandong Provincial Key Laboratory of Mental Disorders, School of Basic Medical Sciences and Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, P.R. China
| | - Bo-Wen Du
- Department of Anatomy and Neurobiology, Shandong Provincial Key Laboratory of Mental Disorders, School of Basic Medical Sciences and Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, P.R. China
| | - Xiao-Lin Chen
- Department of Anatomy and Neurobiology, Shandong Provincial Key Laboratory of Mental Disorders, School of Basic Medical Sciences and Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, P.R. China
| | - Guan-Zhou Fu
- Department of Anatomy and Neurobiology, Shandong Provincial Key Laboratory of Mental Disorders, School of Basic Medical Sciences and Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, P.R. China
| | - Yun-Fei Liu
- Department of Anatomy and Neurobiology, Shandong Provincial Key Laboratory of Mental Disorders, School of Basic Medical Sciences and Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, P.R. China
| | - Shu-Qi Xu
- Department of Anatomy and Neurobiology, Shandong Provincial Key Laboratory of Mental Disorders, School of Basic Medical Sciences and Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, P.R. China
| | - Jia-Chen Shuai
- Department of Anatomy and Neurobiology, Shandong Provincial Key Laboratory of Mental Disorders, School of Basic Medical Sciences and Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, P.R. China
| | - Zhe-Yu Chen
- Department of Anatomy and Neurobiology, Shandong Provincial Key Laboratory of Mental Disorders, School of Basic Medical Sciences and Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, P.R. China
- Institute of Brain Science, Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine, Shanghai 201203, P.R. China
- Institution of Traditional Chinese Medicine Innovation Research, Shandong University of Traditional Chinese Medicine, Jinan 250355, P.R. China
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17
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Jung JH, Wang Y, Mocle AJ, Zhang T, Köhler S, Frankland PW, Josselyn SA. Examining the engram encoding specificity hypothesis in mice. Neuron 2023; 111:1830-1845.e5. [PMID: 36990091 DOI: 10.1016/j.neuron.2023.03.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 02/07/2023] [Accepted: 03/06/2023] [Indexed: 03/30/2023]
Abstract
According to the encoding specificity hypothesis, memory is best recalled by retrieval cues that overlap with training cues. Human studies generally support this hypothesis. However, memories are thought to be stored in neuronal ensembles (engrams), and retrieval cues are thought to reactivate neurons in an engram to induce memory recall. Here, we visualized engrams in mice to test whether retrieval cues that overlap with training cues produce maximal memory recall via high engram reactivation (engram encoding specificity hypothesis). Using variations of cued threat conditioning (pairing conditioned stimulus [CS] with footshock), we manipulated encoding and retrieval conditions along multiple domains, including pharmacological state, external sensory cue, and internal optogenetic cue. Maximal engram reactivation and memory recall occurred when retrieval conditions closely matched training conditions. These findings provide a biological basis for the encoding specificity hypothesis and highlight the important interaction between stored information (engram) and cues available at memory retrieval (ecphory).
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Affiliation(s)
- Jung Hoon Jung
- Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Ave., Toronto, ON M5G 1X8, Canada
| | - Ying Wang
- Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Ave., Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Andrew J Mocle
- Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Ave., Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Tao Zhang
- Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Ave., Toronto, ON M5G 1X8, Canada
| | - Stefan Köhler
- Department of Psychology, University of Western Ontario, London, ON N6A 5C2, Canada; The Brain and Mind Institute, University of Western Ontario, London, ON N6A 3K7, Canada
| | - Paul W Frankland
- Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Ave., Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Psychology, University of Toronto, Toronto, ON M5S 3G3, Canada; Child & Brain Development Program, Canadian Institute for Advanced Research (CIFAR), Toronto, ON M5G 1M1, Canada
| | - Sheena A Josselyn
- Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Ave., Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Psychology, University of Toronto, Toronto, ON M5S 3G3, Canada.
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18
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Kenna M, Marek R, Sah P. Insights into the encoding of memories through the circuitry of fear. Curr Opin Neurobiol 2023; 80:102712. [PMID: 37003106 DOI: 10.1016/j.conb.2023.102712] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 02/27/2023] [Accepted: 02/28/2023] [Indexed: 04/03/2023]
Abstract
Associative learning induces physical changes to a network of cells, known as the memory engram. Fear is widely used as a model to understand the circuit motifs that underpin associative memories. Recent advances suggest that the distinct circuitry engaged by different conditioned stimuli (e.g. tone vs. context) can provide insights into what information is being encoded in the fear engram. Moreover, as the fear memory matures, the circuitry engaged indicates how information is remodelled after learning and hints at potential mechanisms for consolidation. Finally, we propose that the consolidation of fear memories involves plasticity of engram cells through coordinated activity between brain regions, and the inherent characteristics of the circuitry may mediate this process.
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Affiliation(s)
- Matthew Kenna
- Queensland Brain Institute, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Roger Marek
- Queensland Brain Institute, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Pankaj Sah
- Queensland Brain Institute, The University of Queensland, St Lucia, QLD 4072, Australia.
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19
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Bolsius YG, Heckman PRA, Paraciani C, Wilhelm S, Raven F, Meijer EL, Kas MJH, Ramirez S, Meerlo P, Havekes R. Recovering object-location memories after sleep deprivation-induced amnesia. Curr Biol 2023; 33:298-308.e5. [PMID: 36577400 DOI: 10.1016/j.cub.2022.12.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 10/19/2022] [Accepted: 12/02/2022] [Indexed: 12/29/2022]
Abstract
It is well established that sleep deprivation after learning impairs hippocampal memory processes and can cause amnesia. It is unknown, however, whether sleep deprivation leads to the loss of information or merely the suboptimal storage of information that is difficult to retrieve. Here, we show that hippocampal object-location memories formed under sleep deprivation conditions can be successfully retrieved multiple days following training, using optogenetic dentate gyrus (DG) memory engram activation or treatment with the clinically approved phosphodiesterase 4 (PDE4) inhibitor roflumilast. Moreover, the combination of optogenetic DG memory engram activation and roflumilast treatment, 2 days following training and sleep deprivation, made the memory more persistently accessible for retrieval even several days later (i.e., without further optogenetic or pharmacological manipulation). Altogether, our studies in mice demonstrate that sleep deprivation does not necessarily cause memory loss but instead leads to the suboptimal storage of information that cannot be retrieved without drug treatment or optogenetic stimulation. Furthermore, our findings suggest that object-location memories, consolidated under sleep deprivation conditions and thought to be lost, can be made accessible again several days after the learning and sleep deprivation episode, using the clinically approved PDE4 inhibitor roflumilast.
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Affiliation(s)
- Youri G Bolsius
- Neurobiology Expertise Group, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Nijenborgh 7, 9747 AG Groningen, the Netherlands
| | - Pim R A Heckman
- Neurobiology Expertise Group, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Nijenborgh 7, 9747 AG Groningen, the Netherlands; Department of Neuropsychology and Psychopharmacology, Faculty of Psychology and Neuroscience, Maastricht University, Universiteitssingel 40, 6229 ER Maastricht, the Netherlands
| | - Camilla Paraciani
- Neurobiology Expertise Group, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Nijenborgh 7, 9747 AG Groningen, the Netherlands
| | - Sophia Wilhelm
- Neurobiology Expertise Group, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Nijenborgh 7, 9747 AG Groningen, the Netherlands
| | - Frank Raven
- Neurobiology Expertise Group, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Nijenborgh 7, 9747 AG Groningen, the Netherlands
| | - Elroy L Meijer
- Neurobiology Expertise Group, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Nijenborgh 7, 9747 AG Groningen, the Netherlands
| | - Martien J H Kas
- Neurobiology Expertise Group, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Nijenborgh 7, 9747 AG Groningen, the Netherlands
| | - Steve Ramirez
- Department of Psychological and Brain Sciences, The Center for Systems Neuroscience, Boston University, Boston, MA 02215, USA
| | - Peter Meerlo
- Neurobiology Expertise Group, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Nijenborgh 7, 9747 AG Groningen, the Netherlands
| | - Robbert Havekes
- Neurobiology Expertise Group, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Nijenborgh 7, 9747 AG Groningen, the Netherlands.
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20
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Fölsz O, Trouche S, Croset V. Adult-born neurons add flexibility to hippocampal memories. Front Neurosci 2023; 17:1128623. [PMID: 36875670 PMCID: PMC9975346 DOI: 10.3389/fnins.2023.1128623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 01/30/2023] [Indexed: 02/17/2023] Open
Abstract
Although most neurons are generated embryonically, neurogenesis is maintained at low rates in specific brain areas throughout adulthood, including the dentate gyrus of the mammalian hippocampus. Episodic-like memories encoded in the hippocampus require the dentate gyrus to decorrelate similar experiences by generating distinct neuronal representations from overlapping inputs (pattern separation). Adult-born neurons integrating into the dentate gyrus circuit compete with resident mature cells for neuronal inputs and outputs, and recruit inhibitory circuits to limit hippocampal activity. They display transient hyperexcitability and hyperplasticity during maturation, making them more likely to be recruited by any given experience. Behavioral evidence suggests that adult-born neurons support pattern separation in the rodent dentate gyrus during encoding, and they have been proposed to provide a temporal stamp to memories encoded in close succession. The constant addition of neurons gradually degrades old connections, promoting generalization and ultimately forgetting of remote memories in the hippocampus. This makes space for new memories, preventing saturation and interference. Overall, a small population of adult-born neurons appears to make a unique contribution to hippocampal information encoding and removal. Although several inconsistencies regarding the functional relevance of neurogenesis remain, in this review we argue that immature neurons confer a unique form of transience on the dentate gyrus that complements synaptic plasticity to help animals flexibly adapt to changing environments.
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Affiliation(s)
- Orsolya Fölsz
- Department of Biosciences, Durham University, Durham, United Kingdom.,MSc in Neuroscience Programme, University of Oxford, Oxford, United Kingdom
| | - Stéphanie Trouche
- Institute of Functional Genomics, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Vincent Croset
- Department of Biosciences, Durham University, Durham, United Kingdom
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21
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Fan X, Song J, Ma C, Lv Y, Wang F, Ma L, Liu X. Noradrenergic signaling mediates cortical early tagging and storage of remote memory. Nat Commun 2022; 13:7623. [PMID: 36494350 PMCID: PMC9734098 DOI: 10.1038/s41467-022-35342-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 11/30/2022] [Indexed: 12/13/2022] Open
Abstract
The neocortical prefrontal memory engram generated during initial learning is critical for remote episodic memory storage, however, the nature of early cortical tagging remains unknown. Here we found that in mice, increased norepinephrine (NE) release from the locus coeruleus (LC) to the medial prefrontal cortex (mPFC) during contextual fear conditioning (CFC) was critical for engram tagging and remote memory storage, which was regulated by the ventrolateral periaqueductal grey. β-Blocker infusion, or knockout of β1-adrenergic receptor (β1-AR) in the mPFC, impaired the storage of remote CFC memory, which could not be rescued by activation of LC-mPFC NE projection. Remote memory retrieval induced the activation of mPFC engram cells that were tagged during CFC. Inhibition of LC-mPFC NE projection or β1-AR knockout impaired mPFC engram tagging. Juvenile mice had fewer LC NE neurons than adults and showed deficiency in mPFC engram tagging and remote memory of CFC. Activation of β1-AR signaling promoted mPFC early tagging and remote memory storage in juvenile mice. Our data demonstrate that activation of LC NEergic signaling during CFC memory encoding mediates engram early tagging in the mPFC and systems consolidation of remote memory.
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Affiliation(s)
- Xiaocen Fan
- grid.8547.e0000 0001 0125 2443School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Department of Neurology, Pharmacology Research Center, Huashan Hospital, Fudan University, Shanghai, 200032 China ,grid.506261.60000 0001 0706 7839Research Unit of Addiction Memory, Chinese Academy of Medical Sciences (2021RU009), Shanghai, 200032 China
| | - Jiachen Song
- grid.8547.e0000 0001 0125 2443School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Department of Neurology, Pharmacology Research Center, Huashan Hospital, Fudan University, Shanghai, 200032 China ,grid.506261.60000 0001 0706 7839Research Unit of Addiction Memory, Chinese Academy of Medical Sciences (2021RU009), Shanghai, 200032 China
| | - Chaonan Ma
- grid.8547.e0000 0001 0125 2443School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Department of Neurology, Pharmacology Research Center, Huashan Hospital, Fudan University, Shanghai, 200032 China ,grid.506261.60000 0001 0706 7839Research Unit of Addiction Memory, Chinese Academy of Medical Sciences (2021RU009), Shanghai, 200032 China
| | - Yanbo Lv
- grid.8547.e0000 0001 0125 2443School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Department of Neurology, Pharmacology Research Center, Huashan Hospital, Fudan University, Shanghai, 200032 China ,grid.506261.60000 0001 0706 7839Research Unit of Addiction Memory, Chinese Academy of Medical Sciences (2021RU009), Shanghai, 200032 China
| | - Feifei Wang
- grid.8547.e0000 0001 0125 2443School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Department of Neurology, Pharmacology Research Center, Huashan Hospital, Fudan University, Shanghai, 200032 China ,grid.506261.60000 0001 0706 7839Research Unit of Addiction Memory, Chinese Academy of Medical Sciences (2021RU009), Shanghai, 200032 China
| | - Lan Ma
- grid.8547.e0000 0001 0125 2443School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Department of Neurology, Pharmacology Research Center, Huashan Hospital, Fudan University, Shanghai, 200032 China ,grid.506261.60000 0001 0706 7839Research Unit of Addiction Memory, Chinese Academy of Medical Sciences (2021RU009), Shanghai, 200032 China
| | - Xing Liu
- grid.8547.e0000 0001 0125 2443School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Department of Neurology, Pharmacology Research Center, Huashan Hospital, Fudan University, Shanghai, 200032 China ,grid.506261.60000 0001 0706 7839Research Unit of Addiction Memory, Chinese Academy of Medical Sciences (2021RU009), Shanghai, 200032 China
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22
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Howe ML. Early Childhood Memories Are not Repressed: Either They Were Never Formed or Were Quickly Forgotten. Top Cogn Sci 2022. [PMID: 36458626 DOI: 10.1111/tops.12636] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 03/11/2022] [Accepted: 07/11/2022] [Indexed: 12/03/2022]
Abstract
Early childhood events are rarely remembered in adulthood. In fact, memory for these early experiences declines during childhood itself. This holds regardless of whether these memories of autobiographical experiences are traumatic or mundane, everyday experiences. Indeed, what people tend to remember from their childhoods involves relatively innocuous experiences, ones often devoid of emotion. In this article, I provide an overview of the types of memories adults recall from their childhoods and the ages at which these memories are believed to have been formed. Along the way, I provide a brief exegesis of the neurobiological and cognitive underpinnings of early memory development. I will show that changes and growth in neural interconnectivity as well as the development of various cognitive structures (e.g., the inception of the cognitive self) help propel the emergence of a mature autobiographical memory system, one that can and does serve as a reconstructive base for remembering events that occur in later childhood and adulthood. During the course of this review, I detail the nature of early memories, their fragility, and the adaptive consequences of forgetting and supplanting these memories with newer, more age-appropriate experiences throughout childhood.
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Affiliation(s)
- Mark L Howe
- Department of Psychology, School of Health and Psychological Sciences, City, University of London
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23
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Park S, Jung JH, Karimi SA, Jacob AD, Josselyn SA. Opto-extinction of a threat memory in mice. Brain Res Bull 2022; 191:61-68. [DOI: 10.1016/j.brainresbull.2022.10.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 10/17/2022] [Indexed: 11/02/2022]
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24
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Lods M, Mortessagne P, Pacary E, Terral G, Farrugia F, Mazier W, Masachs N, Charrier V, Cota D, Ferreira G, Abrous DN, Tronel S. Chemogenetic stimulation of adult neurogenesis, and not neonatal neurogenesis, is sufficient to improve long-term memory accuracy. Prog Neurobiol 2022; 219:102364. [DOI: 10.1016/j.pneurobio.2022.102364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 09/21/2022] [Accepted: 10/06/2022] [Indexed: 12/05/2022]
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25
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Miranda JM, Cruz E, Bessières B, Alberini CM. Hippocampal parvalbumin interneurons play a critical role in memory development. Cell Rep 2022; 41:111643. [PMID: 36384113 PMCID: PMC9737056 DOI: 10.1016/j.celrep.2022.111643] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 08/16/2022] [Accepted: 10/19/2022] [Indexed: 11/18/2022] Open
Abstract
Episodic memories formed in early childhood rapidly decay, but their latent traces remain stored long term. These memories require the dorsal hippocampus (dHPC) and seem to undergo a developmental critical period. It remains to be determined whether the maturation of parvalbumin interneurons (PVIs), a major mechanism of critical periods, contributes to memory development. Here, we show that episodic infantile learning significantly increases the levels of parvalbumin in the dHPC 48 h after training. Chemogenetic inhibition of PVIs before learning indicated that these neurons are required for infantile memory formation. A bilateral dHPC injection of the γ-aminobutyric acid type A receptor agonist diazepam after training elicited long-term memory expression in infant rats, although direct PVI chemogenetic activation had no effect. Finally, PVI activity was required for brain-derived neurotrophic factor (BDNF)-dependent maturation of memory competence, i.e., adult-like long-term memory expression. Thus, dHPC PVIs are critical for the formation of infantile memories and for memory development.
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Affiliation(s)
- Janelle M Miranda
- Center for Neural Science, New York University, 4 Washington Place, New York, NY 10003, USA
| | - Emmanuel Cruz
- Center for Neural Science, New York University, 4 Washington Place, New York, NY 10003, USA
| | - Benjamin Bessières
- Center for Neural Science, New York University, 4 Washington Place, New York, NY 10003, USA
| | - Cristina M Alberini
- Center for Neural Science, New York University, 4 Washington Place, New York, NY 10003, USA.
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López-Oropeza G, Durán P, Martínez-Canabal A. Maternal enrichment increases infantile spatial amnesia mediated by postnatal neurogenesis modulation. Front Behav Neurosci 2022; 16:971359. [PMID: 36090654 PMCID: PMC9452746 DOI: 10.3389/fnbeh.2022.971359] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 07/27/2022] [Indexed: 11/13/2022] Open
Abstract
Infantile amnesia, the inability to form long-lasting episodic memories, is a phenomenon extensively known but with no clear understanding of its origins. However, a recent study showed that high rates of hippocampal postnatal neurogenesis degrade episodic-like memories in infants a few days after memory acquisition. Additionally, new studies indicate that exposure to an enriched environment in mice leads to high hippocampal neurogenesis in their offspring. Nevertheless, it is still unclear how this intergenerational trait affects the persistence of hippocampal memories. Therefore, we evaluated spatial memory retention in the offspring of enriched female mice after weaning to address this question. Ten days after spatial learning, we tested memory retention, observing that the offspring of enriched dams increased spatial memory failure; this finding correlates with high proliferation rates in the hippocampus. Furthermore, we evaluated the causal relationship between postnatal hippocampal neurogenesis and memory failure using the antiproliferative drug Temozolomide (TMZ), which rescued spatial memory retrieval. Finally, we evaluated neuronal activity in the hippocampus quantifying the cells expressing the immediate early gene c-Fos. This evaluation showed engram modifications between groups. This neural activity pattern indicates that the high neurogenesis rates can modify memory engrams and cognitive performance. In conclusion, the inherited increase of hippocampal neurogenesis by enriched dams leads to plastic changes that exacerbate infantile amnesia in a spatial task.
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Featherstone RE, Shimada T, Crown LM, Melnychenko O, Yi J, Matsumoto M, Tajinda K, Mihara T, Adachi M, Siegel SJ. Calcium/calmodulin-dependent protein kinase IIα heterozygous knockout mice show electroencephalogram and behavioral changes characteristic of a subpopulation of schizophrenia and intellectual impairment. Neuroscience 2022; 499:104-117. [PMID: 35901933 DOI: 10.1016/j.neuroscience.2022.07.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Revised: 07/17/2022] [Accepted: 07/19/2022] [Indexed: 12/01/2022]
Abstract
Cognitive deficit remains an intractable symptom of schizophrenia, accounting for substantial disability. Despite this, little is known about the cause of cognitive dysfunction in schizophrenia. Recent studies suggest that schizophrenia patients show several changes in dentate gyrus structure and functional characteristic of immaturity. The immature dentate gyrus (iDG) has been replicated in several mouse models, most notably the αCaMKII heterozygous mouse (CaMKIIa-hKO). The current study characterizes behavioral phenotypes of CaMKIIa-hKO mice and determines their neurophysiological profile using electroencephalogram (EEG) recording from hippocampus. CaMKIIa-hKO mice were hypoactive in home-cage environment; however, they displayed less anxiety-like phenotype, suggestive of impulsivity-like behavior. In addition, severe cognitive dysfunction was evident in CaMKIIa-hKO mice as examined by novel object recognition and contextual fear conditioning. Several EEG phenomena established in both patients and relevant animal models indicate key pathological changes associated with the disease, include auditory event-related potentials and time-frequency EEG oscillations. CaMKIIa-hKO mice showed altered event-related potentials characterized by an increase in amplitude of the N40 and P80, as well as increased P80 latency. These mice also showed increased power in theta range time-frequency measures. Additionally, CaMKIIa-hKO mice showed spontaneous bursts of spike wave activity, possibly indicating absence seizures. The GABAB agonist baclofen increased, while the GABAB antagonist CGP35348 and the T-Type Ca2+ channel blocker Ethosuximide decreased spike wave burst frequency. None of these changes in event-related potentials or EEG oscillations are characteristic of those observed in general population of patients with schizophrenia; yet, CaMKIIa-hKO mice likely model a subpopulation of patients with schizophrenia.
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Affiliation(s)
- Robert E Featherstone
- Department of Psychiatry and Behavioral Sciences, University of Southern California, Los, Angeles, CA, USA
| | - Takeshi Shimada
- Drug Discovery Research, Astellas Pharma, Inc, Tsukuba, Japan
| | - Lindsey M Crown
- Department of Psychiatry and Behavioral Sciences, University of Southern California, Los, Angeles, CA, USA
| | - Olya Melnychenko
- Department of Psychiatry and Behavioral Sciences, University of Southern California, Los, Angeles, CA, USA
| | - Janice Yi
- Department of Psychiatry and Behavioral Sciences, University of Southern California, Los, Angeles, CA, USA
| | | | | | - Takuma Mihara
- Drug Discovery Research, Astellas Pharma, Inc, Tsukuba, Japan
| | - Megumi Adachi
- Astellas Research Institute of America, San Diego, CA, USA.
| | - Steven J Siegel
- Department of Psychiatry and Behavioral Sciences, University of Southern California, Los, Angeles, CA, USA.
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Zhang Y, Smolen P, Alberini CM, Baxter DA, Byrne JH. Computational analysis of memory consolidation following inhibitory avoidance (IA) training in adult and infant rats: Critical roles of CaMKIIα and MeCP2. PLoS Comput Biol 2022; 18:e1010239. [PMID: 35759520 PMCID: PMC9269953 DOI: 10.1371/journal.pcbi.1010239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 07/08/2022] [Accepted: 05/23/2022] [Indexed: 11/18/2022] Open
Abstract
Key features of long-term memory (LTM), such as its stability and persistence, are acquired during processes collectively referred to as consolidation. The dynamics of biological changes during consolidation are complex. In adult rodents, consolidation exhibits distinct periods during which the engram is more or less resistant to disruption. Moreover, the ability to consolidate memories differs during developmental periods. Although the molecular mechanisms underlying consolidation are poorly understood, the initial stages rely on interacting signaling pathways that regulate gene expression, including brain-derived neurotrophic factor (BDNF) and Ca2+/calmodulin-dependent protein kinase II α (CaMKIIα) dependent feedback loops. We investigated the ways in which these pathways may contribute to developmental and dynamical features of consolidation. A computational model of molecular processes underlying consolidation following inhibitory avoidance (IA) training in rats was developed. Differential equations described the actions of CaMKIIα, multiple feedback loops regulating BDNF expression, and several transcription factors including methyl-CpG binding protein 2 (MeCP2), histone deacetylase 2 (HDAC2), and SIN3 transcription regulator family member A (Sin3a). This model provides novel explanations for the (apparent) rapid forgetting of infantile memory and the temporal progression of memory consolidation in adults. Simulations predict that dual effects of MeCP2 on the expression of bdnf, and interaction between MeCP2 and CaMKIIα, play critical roles in the rapid forgetting of infantile memory and the progress of memory resistance to disruptions. These insights suggest new potential targets of therapy for memory impairment.
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Affiliation(s)
- Yili Zhang
- Department of Neurobiology and Anatomy; W.M. Keck Center for the Neurobiology of Learning and Memory; The University of Texas Medical School at Houston, Houston, Texas, United States of America
| | - Paul Smolen
- Department of Neurobiology and Anatomy; W.M. Keck Center for the Neurobiology of Learning and Memory; The University of Texas Medical School at Houston, Houston, Texas, United States of America
| | - Cristina M. Alberini
- Center for Neural Science, New York University, New York City, New York, United States of America
| | - Douglas A. Baxter
- Department of Neurobiology and Anatomy; W.M. Keck Center for the Neurobiology of Learning and Memory; The University of Texas Medical School at Houston, Houston, Texas, United States of America
- Department of Neurobiology and Experimental Therapeutics, College of Medicine, Texas A&M University, Houston, Texas, United States of America
| | - John H. Byrne
- Department of Neurobiology and Anatomy; W.M. Keck Center for the Neurobiology of Learning and Memory; The University of Texas Medical School at Houston, Houston, Texas, United States of America
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29
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Berdugo-Vega G, Graeff J. Inquiring the librarian about the location of memory. Cogn Neurosci 2022; 13:134-136. [PMID: 35616221 DOI: 10.1080/17588928.2022.2076075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Where memories are stored in the brain is an age-old question in psychology and neuroscience alike. In particular, whether hippocampus-encoded memories are transferred to the cortex or remain hippocampus-dependent over time has not been definitely answered. New evidence from fMRI studies in humans suggest that while hippocampo-cortical connections lose weight during declarative memory consolidation, the hippocampus - alongside corticocortical connections - stays equally engaged between recent and remote memory recall. These findings lend experimental support for the indexing theory of memory consolidation, which postulates the hippocampus to act as a librarian to retrieve the cortical books of memory.
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Affiliation(s)
- Gabriel Berdugo-Vega
- Laboratory of Neuroepigenetics, Brain Mind Institute, School of Life Sciences, Ecole Polytechnique Fédérale Lausanne (EPFL-EPFL-SV-BMI-UPGRAEFF), Station 19, Lausanne, Switzerland
| | - Johannes Graeff
- Laboratory of Neuroepigenetics, Brain Mind Institute, School of Life Sciences, Ecole Polytechnique Fédérale Lausanne (EPFL-EPFL-SV-BMI-UPGRAEFF), Station 19, Lausanne, Switzerland
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30
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Ortega-de San Luis C, Ryan TJ. Understanding the physical basis of memory: Molecular mechanisms of the engram. J Biol Chem 2022; 298:101866. [PMID: 35346687 PMCID: PMC9065729 DOI: 10.1016/j.jbc.2022.101866] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 03/08/2022] [Accepted: 03/11/2022] [Indexed: 12/18/2022] Open
Abstract
Memory, defined as the storage and use of learned information in the brain, is necessary to modulate behavior and critical for animals to adapt to their environments and survive. Despite being a cornerstone of brain function, questions surrounding the molecular and cellular mechanisms of how information is encoded, stored, and recalled remain largely unanswered. One widely held theory is that an engram is formed by a group of neurons that are active during learning, which undergoes biochemical and physical changes to store information in a stable state, and that are later reactivated during recall of the memory. In the past decade, the development of engram labeling methodologies has proven useful to investigate the biology of memory at the molecular and cellular levels. Engram technology allows the study of individual memories associated with particular experiences and their evolution over time, with enough experimental resolution to discriminate between different memory processes: learning (encoding), consolidation (the passage from short-term to long-term memories), and storage (the maintenance of memory in the brain). Here, we review the current understanding of memory formation at a molecular and cellular level by focusing on insights provided using engram technology.
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Affiliation(s)
- Clara Ortega-de San Luis
- School of Biochemistry and Immunology and Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland.
| | - Tomás J Ryan
- School of Biochemistry and Immunology and Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland; Florey Institute of Neuroscience and Mental Health, Melbourne Brain Centre, University of Melbourne, Parkville, Victoria, Australia; Child & Brain Development Program, Canadian Institute for Advanced Research (CIFAR), Toronto, Ontario, Canada.
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Leuenberger M. Memory Modification and Authenticity: A Narrative Approach. NEUROETHICS-NETH 2022; 15:10. [PMID: 35222738 PMCID: PMC8847193 DOI: 10.1007/s12152-022-09489-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 11/11/2021] [Indexed: 12/16/2022]
Abstract
The potential of memory modification techniques (MMTs) has raised concerns and sparked a debate in neuroethics, particularly in the context of identity and authenticity. This paper addresses the question whether and how MMTs influence authenticity. I proceed by drawing two distinctions within the received views on authenticity. From this, I conclude that an analysis of MMTs based on a dual-basis, process view of authenticity is warranted, which implies that the influence of MMTs on authenticity crucially depends on the specifics of how memory modification would eventually work. Therefore, I continue with a systematic analysis of possible properties of MMTs in which I distinguish between the dimensions of memories and the kinds of experiences that can be modified as well as the properties of the process of memory modification. The impact of MMTs on authenticity is analyzed regarding the possible properties of MMTs and based on a narrative approach to authenticity which fulfills the requirements of a dual-basis, process view of authenticity. Lastly, I explore the potential of MMTs to shift the balance between self-discovery and self-creation within authenticity and thereby alter the concept itself as well as the value of authenticity.
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Affiliation(s)
- Muriel Leuenberger
- Oxford Uehiro Centre for Practical Ethics, Faculty of Philosophy, University of Oxford, Suite 8 Littlegate House, 16/17 St Ebbe’s Street, Oxford, OX1 1PT UK
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32
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Ryan TJ, Frankland PW. Forgetting as a form of adaptive engram cell plasticity. Nat Rev Neurosci 2022; 23:173-186. [PMID: 35027710 DOI: 10.1038/s41583-021-00548-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/25/2021] [Indexed: 12/30/2022]
Abstract
One leading hypothesis suggests that memories are stored in ensembles of neurons (or 'engram cells') and that successful recall involves reactivation of these ensembles. A logical extension of this idea is that forgetting occurs when engram cells cannot be reactivated. Forms of 'natural forgetting' vary considerably in terms of their underlying mechanisms, time course and reversibility. However, we suggest that all forms of forgetting involve circuit remodelling that switches engram cells from an accessible state (where they can be reactivated by natural recall cues) to an inaccessible state (where they cannot). In many cases, forgetting rates are modulated by environmental conditions and we therefore propose that forgetting is a form of neuroplasticity that alters engram cell accessibility in a manner that is sensitive to mismatches between expectations and the environment. Moreover, we hypothesize that disease states associated with forgetting may hijack natural forgetting mechanisms, resulting in reduced engram cell accessibility and memory loss.
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Affiliation(s)
- Tomás J Ryan
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin, Ireland. .,Trinity College Institute for Neuroscience, Trinity College Dublin, Dublin, Ireland. .,Florey Institute of Neuroscience and Mental Health, Melbourne Brain Centre, University of Melbourne, Melbourne, Victoria, Australia. .,Child & Brain Development Program, Canadian Institute for Advanced Research (CIFAR), Toronto, Ontario, Canada.
| | - Paul W Frankland
- Child & Brain Development Program, Canadian Institute for Advanced Research (CIFAR), Toronto, Ontario, Canada. .,Program in Neurosciences & Mental Health, Hospital for Sick Children, Toronto, Ontario, Canada. .,Department of Psychology, University of Toronto, Toronto, Ontario, Canada. .,Department of Physiology, University of Toronto, Toronto, Ontario, Canada. .,Institute of Medical Sciences, University of Toronto, Toronto, Ontario, Canada.
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Ohana O, Alberini CM, Donato F. Introduction to the special issue on the ontogeny of hippocampal functions. Hippocampus 2022; 32:69-72. [PMID: 35005808 PMCID: PMC9303776 DOI: 10.1002/hipo.23406] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Ora Ohana
- Institute for Molecular and Cellular Cognition, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | | | - Flavio Donato
- Biozentrum of the University of Basel, Basel, Switzerland
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34
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Abrous DN, Koehl M, Lemoine M. A Baldwin interpretation of adult hippocampal neurogenesis: from functional relevance to physiopathology. Mol Psychiatry 2022; 27:383-402. [PMID: 34103674 PMCID: PMC8960398 DOI: 10.1038/s41380-021-01172-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 05/03/2021] [Accepted: 05/12/2021] [Indexed: 02/05/2023]
Abstract
Hippocampal adult neurogenesis has been associated to many cognitive, emotional, and behavioral functions and dysfunctions, and its status as a selected effect or an "appendix of the brain" has been debated. In this review, we propose to understand hippocampal neurogenesis as the process underlying the "Baldwin effect", a particular situation in evolution where fitness does not rely on the natural selection of genetic traits, but on "ontogenetic adaptation" to a changing environment. This supports the view that a strong distinction between developmental and adult hippocampal neurogenesis is made. We propose that their functions are the constitution and the lifelong adaptation, respectively, of a basic repertoire of cognitive and emotional behaviors. This lifelong adaptation occurs through new forms of binding, i.e., association or dissociation of more basic elements. This distinction further suggests that a difference is made between developmental vulnerability (or resilience), stemming from dysfunctional (or highly functional) developmental hippocampal neurogenesis, and adult vulnerability (or resilience), stemming from dysfunctional (or highly functional) adult hippocampal neurogenesis. According to this hypothesis, developmental and adult vulnerability are distinct risk factors for various mental disorders in adults. This framework suggests new avenues for research on hippocampal neurogenesis and its implication in mental disorders.
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Affiliation(s)
- Djoher Nora Abrous
- Univ. Bordeaux, INSERM, Neurocentre Magendie, U1215, Neurogenesis and Pathophysiology group, F-33000, Bordeaux, France.
| | - Muriel Koehl
- grid.412041.20000 0001 2106 639XUniv. Bordeaux, INSERM, Neurocentre Magendie, U1215, Neurogenesis and Pathophysiology group, F-33000 Bordeaux, France
| | - Maël Lemoine
- grid.412041.20000 0001 2106 639XUniversity Bordeaux, CNRS, ImmunoConcEpT, UMR 5164, Bordeaux, France
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35
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Learning and memory: Shuffling memory traces by relearning. Curr Biol 2021; 31:R1588-R1591. [PMID: 34932971 DOI: 10.1016/j.cub.2021.11.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Memory engram cells are a subpopulation of neurons activated during learning, and are necessary and sufficient for memory recall. New findings show that relearning induces the turnover of the memory engram cell population involved in fear memory recall.
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36
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Shan X, Contreras MP, Mendez M, Born J, Inostroza M. Unfolding of spatial representation at systems level in infant rats. Hippocampus 2021; 32:121-133. [PMID: 34786798 DOI: 10.1002/hipo.23392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 10/25/2021] [Accepted: 11/01/2021] [Indexed: 11/10/2022]
Abstract
Spatial representations enable navigation from early life on. However, the brain regions essential to form spatial representations, like the hippocampus, are considered functionally immature before weaning. Here, we examined the formation of representations of space in rat pups on postnatal day (PD) 16, using a simple habituation paradigm where the pups were exposed to an arena on three occasions, separated by ~140 min. Whereas on the first two occasions the arena was the same, on the third "test" occasion either proximal cues (Prox group), or distal cues (Dist group), or proximal and distal cues (Prox-Dist group), or no cues (No-change group) were rearranged. Locomotion (distance traveled) was used as behavioral measure of habituation, and c-Fos expression to measure regional brain activity at test. Locomotion generally decreased across the first two occasions. At test, it reached a minimum in the No-change group, indicating familiarity with the spatial conditions. By contrast, the Prox-Dist group displayed a significant increase in locomotion which was less robust in the Prox group and absent in the Dist group, a pattern suggesting that the pups relied more on proximal than distal cues during spatial exploration. c-Fos activity in the No-change group was significantly suppressed in the hippocampus (CA1, CA3, dentate gyrus) but simultaneously enhanced in the prelimbic area (PL) of the medial prefrontal cortex, compared with untreated Home-cage controls, pointing to a possible involvement of the PL in regulating locomotion in familiar spaces. By contrast, in both Prox-Dist and Prox groups c-Fos activity was enhanced in hippocampal CA1 and CA3 regions, suggesting these regions might be particularly involved in regulating exploration of spatial novelty. Our findings show that functional representations of space at a systems level are formed already in pre-weanling rats.
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Affiliation(s)
- Xia Shan
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany.,Graduate School of Neural & Behavioral Science, International Max Planck Research School, Tübingen, Germany
| | - María P Contreras
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany.,Graduate School of Neural & Behavioral Science, International Max Planck Research School, Tübingen, Germany
| | - Marta Mendez
- Laboratory of Neuroscience, Department of Psychology, Instituto de Neurociencias del Principado de Asturias (INEUROPA), University of Oviedo, Plaza Feijoo, Oviedo, Spain
| | - Jan Born
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany.,German Center for Diabetes Research (DZD), Institute for Diabetes Research & Metabolic Diseases of the Helmholtz Center Munich at the University Tübingen (IDM), Tübingen, Germany.,Werner Reichert Center for Integrative Neuroscience, University of Tübingen, Tübingen, Germany
| | - Marion Inostroza
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany
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37
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Botterill JJ, Khlaifia A, Walters BJ, Brimble MA, Scharfman HE, Arruda-Carvalho M. Off-Target Expression of Cre-Dependent Adeno-Associated Viruses in Wild-Type C57BL/6J Mice. eNeuro 2021; 8:ENEURO.0363-21.2021. [PMID: 34785571 PMCID: PMC8614227 DOI: 10.1523/eneuro.0363-21.2021] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 10/26/2021] [Accepted: 10/29/2021] [Indexed: 11/21/2022] Open
Abstract
Adeno-associated viruses (AAVs) are a commonly used tool in neuroscience to efficiently label, trace, and/or manipulate neuronal populations. Highly specific targeting can be achieved through recombinase-dependent AAVs in combination with transgenic rodent lines that express Cre-recombinase in specific cell types. Visualization of viral expression is typically achieved through fluorescent reporter proteins (e.g., GFP or mCherry) packaged within the AAV genome. Although nonamplified fluorescence is usually sufficient to observe viral expression, immunohistochemical amplification of the fluorescent reporter is routinely used to improve viral visualization. In the present study, Cre-dependent AAVs were injected into the neocortex of wild-type C57BL/6J mice. While we observed weak but consistent nonamplified off-target double inverted open reading frame (DIO) expression in C57BL/6J mice, antibody amplification of the GFP or mCherry reporter revealed notable Cre-independent viral expression. Off-target expression of DIO constructs in wild-type C57BL/6J mice occurred independent of vendor, AAV serotype, or promoter. We also evaluated whether Cre-independent expression had functional effects via designer receptors exclusively activated by designer drugs (DREADDs). The DREADD agonist C21 (compound 21) had no effect on contextual fear conditioning or c-Fos expression in DIO-hM3Dq-mCherry+ cells of C57BL/6J mice. Together, our results indicate that DIO constructs have off-target expression in wild-type subjects. Our findings are particularly important for the design of experiments featuring sensitive systems and/or quantitative measurements that could be negatively impacted by off-target expression.
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Affiliation(s)
- Justin J Botterill
- Department of Psychology, University of Toronto Scarborough, Toronto, Ontario M1C 1A4, Canada
| | - Abdessattar Khlaifia
- Department of Psychology, University of Toronto Scarborough, Toronto, Ontario M1C 1A4, Canada
| | - Brandon J Walters
- Department of Cell & Systems Biology, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, Canada
| | - Mark A Brimble
- Department of Surgery, St. Jude Children's Research Hospital, Memphis, Tennnessee 38105
| | - Helen E Scharfman
- Center for Dementia Research, The Nathan Kline Institute for Psychiatric Research, Orangeburg, New York 10962
- Departments of Child & Adolescent Psychiatry, Neuroscience & Physiology, and Psychiatry, and New York University Neuroscience Institute, New York University Langone Health, New York, New York 10016
| | - Maithe Arruda-Carvalho
- Department of Psychology, University of Toronto Scarborough, Toronto, Ontario M1C 1A4, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada
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38
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Developmental emergence of persistent memory for contextual and auditory fear in mice. Learn Mem 2021; 28:414-421. [PMID: 34663694 DOI: 10.1101/lm.053471.121] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 07/30/2021] [Indexed: 02/02/2023]
Abstract
The ability to generate memories that persist throughout a lifetime (that is, memory persistence) emerges in early development across species. Although it has been shown that persistent fear memories emerge between late infancy and adolescence in mice, it is unclear exactly when this transition takes place, and whether two major fear conditioning tasks, contextual and auditory fear, share the same time line of developmental onset. Here, we compared the ontogeny of remote contextual and auditory fear in C57BL/6J mice across early life. Mice at postnatal day (P)15, 21, 25, 28, and 30 underwent either contextual or auditory fear training and were tested for fear retrieval 1 or 30 d later. We found that mice displayed 30-d memory for context- and tone-fear starting at P25. We did not find sex differences in the ontogeny of either type of fear memory. Furthermore, 30-d contextual fear retrieval led to an increase in the number of c-Fos positive cells in the prelimbic region of the prefrontal cortex only at an age in which the contextual fear memory was successfully retrieved. These data delineate a precise time line for the emergence of persistent contextual and auditory fear memories in mice and suggest that the prelimbic cortex is only recruited for remote memory recall upon the onset of memory persistence.
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Cho HY, Shin W, Lee HS, Lee Y, Kim M, Oh JP, Han J, Jeong Y, Suh B, Kim E, Han JH. Turnover of fear engram cells by repeated experience. Curr Biol 2021; 31:5450-5461.e4. [PMID: 34687608 DOI: 10.1016/j.cub.2021.10.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 09/07/2021] [Accepted: 10/01/2021] [Indexed: 10/20/2022]
Abstract
A sparse population of neurons active during a learning event has been identified as memory engram cells. However, cells that are recruited to support memory when experience is repeated have been scarcely explored. Evidence from previous studies provides contradictory views. To address these questions, we employed learning-dependent cell labeling in the lateral amygdala (LA) and applied electrophysiological recording, spine imaging, and optogenetic tools to the labeled neurons with or without retraining. We found that engram cells established from original fear learning became dispensable for memory retrieval specifically with relearning, and this correlated with a reduction of synaptic transmission and loss of dendritic spines in these neurons. Despite such decreased connectivity, direct activation of these neurons resulted in fear-memory recall. We further identified that repeated memory was encoded in neurons active during relearning. These results suggest a shift in neuronal ensembles encoding fear memory in the LA by relearning through disconnection of the existing engram neurons established from original experience.
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Affiliation(s)
- Hye-Yeon Cho
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Yuseong-gu, Daejeon 34141, Korea; KAIST Institute for the BioCentury (KIB), Korea Advanced Institute of Science and Technology (KAIST), Yuseong-gu, Daejeon 34141, Korea
| | - Wangyong Shin
- Center for Synaptic Brain Dysfunctions, Institute for Basic Science (IBS), Daejeon 34141, Korea
| | - Han-Sol Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Yuseong-gu, Daejeon 34141, Korea; KAIST Institute for the BioCentury (KIB), Korea Advanced Institute of Science and Technology (KAIST), Yuseong-gu, Daejeon 34141, Korea
| | - Yeji Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Yuseong-gu, Daejeon 34141, Korea; KAIST Institute for the BioCentury (KIB), Korea Advanced Institute of Science and Technology (KAIST), Yuseong-gu, Daejeon 34141, Korea
| | - Mujun Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Yuseong-gu, Daejeon 34141, Korea; KAIST Institute for the BioCentury (KIB), Korea Advanced Institute of Science and Technology (KAIST), Yuseong-gu, Daejeon 34141, Korea
| | - Jung-Pyo Oh
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Yuseong-gu, Daejeon 34141, Korea; KAIST Institute for the BioCentury (KIB), Korea Advanced Institute of Science and Technology (KAIST), Yuseong-gu, Daejeon 34141, Korea
| | - Junho Han
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Yuseong-gu, Daejeon 34141, Korea; KAIST Institute for the BioCentury (KIB), Korea Advanced Institute of Science and Technology (KAIST), Yuseong-gu, Daejeon 34141, Korea
| | - Yire Jeong
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Yuseong-gu, Daejeon 34141, Korea; KAIST Institute for the BioCentury (KIB), Korea Advanced Institute of Science and Technology (KAIST), Yuseong-gu, Daejeon 34141, Korea
| | - Boin Suh
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Yuseong-gu, Daejeon 34141, Korea; KAIST Institute for the BioCentury (KIB), Korea Advanced Institute of Science and Technology (KAIST), Yuseong-gu, Daejeon 34141, Korea
| | - Eunjoon Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Yuseong-gu, Daejeon 34141, Korea; Center for Synaptic Brain Dysfunctions, Institute for Basic Science (IBS), Daejeon 34141, Korea
| | - Jin-Hee Han
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Yuseong-gu, Daejeon 34141, Korea; KAIST Institute for the BioCentury (KIB), Korea Advanced Institute of Science and Technology (KAIST), Yuseong-gu, Daejeon 34141, Korea.
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40
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Bisaz R, Bessières B, Miranda JM, Travaglia A, Alberini CM. Recovery of memory from infantile amnesia is developmentally constrained. ACTA ACUST UNITED AC 2021; 28:300-306. [PMID: 34400531 PMCID: PMC8372561 DOI: 10.1101/lm.052621.120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 07/05/2021] [Indexed: 11/24/2022]
Abstract
Episodic memories formed during infancy are rapidly forgotten, a phenomenon associated with infantile amnesia, the inability of adults to recall early-life memories. In both rats and mice, infantile memories, although not expressed, are actually stored long term in a latent form. These latent memories can be reinstated later in life by certain behavioral reminders or by artificial reactivations of neuronal ensembles activated at training. Whether the recovery of infantile memories is limited by developmental age, maternal presence, or contingency of stimuli presentation remains to be determined. Here, we show that the return of inhibitory avoidance memory in rats following a behavioral reactivation consisting of an exposure to the context (conditioned stimuli [CS]) and footshock (unconditioned stimuli [US]) given in a temporally unpaired fashion, is evident immediately after US and is limited by the developmental age at which the reactivations are presented; however, it is not influenced by maternal presence or the time interval between training and reactivation. We conclude that one limiting factor for infantile memory reinstatement is developmental age, suggesting that a brain maturation process is necessary to allow the recovery of a “lost” infantile memory.
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Affiliation(s)
- Reto Bisaz
- Center for Neural Science, New York University, New York, New York 10003, USA
| | - Benjamin Bessières
- Center for Neural Science, New York University, New York, New York 10003, USA
| | - Janelle M Miranda
- Center for Neural Science, New York University, New York, New York 10003, USA
| | - Alessio Travaglia
- Center for Neural Science, New York University, New York, New York 10003, USA
| | - Cristina M Alberini
- Center for Neural Science, New York University, New York, New York 10003, USA
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41
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Ko SY, Frankland PW. Neurogenesis-dependent transformation of hippocampal engrams. Neurosci Lett 2021; 762:136176. [PMID: 34400284 DOI: 10.1016/j.neulet.2021.136176] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 07/29/2021] [Accepted: 08/11/2021] [Indexed: 11/29/2022]
Abstract
In humans and other mammals, memories of events are encoded by neuronal ensembles (or engrams) in the hippocampus. The mnemonic information stored in these engrams can then be used to guide future behavior, including prediction- and decision-making in dynamic environments. While some hippocampal engrams may be persistently stored, others are modified over time, suggesting that the represented memories may also be transformed. How might hippocampal engrams be modified through time? Adult hippocampal neurogenesis represents one process that continuously rewires hippocampal circuitry, presumably including stored hippocampal engrams. At intermediate stages, we propose that neurogenesis-mediated rewiring of hippocampal engram circuitry induces forgetting of specific stimulus attributes, and this less precise engram allows for generalization. At more advanced stages, we propose that neurogenesis-mediated rewiring of hippocampal engram circuitry leads to silencing of hippocampal engrams, rendering them no longer accessible by natural retrieval cues.
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Affiliation(s)
- Sangyoon Y Ko
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada; Temerty Centre for AI Research and Education in Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Paul W Frankland
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Psychology, University of Toronto, Toronto, ON M5S 3G3, Canada; Institute of Medical Sciences, University of Toronto, Toronto, ON M5S 1A8, Canada; Child and Brain Development Program, Canadian Institute for Advanced Research (CIFAR), Toronto, ON M5G 1M1, Canada.
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42
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Ellis CT, Skalaban LJ, Yates TS, Bejjanki VR, Córdova NI, Turk-Browne NB. Evidence of hippocampal learning in human infants. Curr Biol 2021; 31:3358-3364.e4. [PMID: 34022155 DOI: 10.1016/j.cub.2021.04.072] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 03/19/2021] [Accepted: 04/28/2021] [Indexed: 01/26/2023]
Abstract
The hippocampus is essential for human memory.1 The protracted maturation of memory capacities from infancy through early childhood2-4 is thus often attributed to hippocampal immaturity.5-7 The hippocampus of human infants has been characterized in terms of anatomy,8,9 but its function has never been tested directly because of technical challenges.10,11 Here, we use recently developed methods for task-based fMRI in awake human infants12 to test the hypothesis that the infant hippocampus supports statistical learning.13-15 Hippocampal activity increased with exposure to visual sequences of objects when the temporal order contained regularities to be learned, compared to when the order was random. Despite the hippocampus doubling in anatomical volume across infancy, learning-related functional activity bore no relationship to age. This suggests that the hippocampus is recruited for statistical learning at the youngest ages in our sample, around 3 months. Within the hippocampus, statistical learning was clearer in anterior than posterior divisions. This is consistent with the theory that statistical learning occurs in the monosynaptic pathway,16 which is more strongly represented in the anterior hippocampus.17,18 The monosynaptic pathway develops earlier than the trisynaptic pathway, which is linked to episodic memory,19,20 raising the possibility that the infant hippocampus participates in statistical learning before it forms durable memories. Beyond the hippocampus, the medial prefrontal cortex showed statistical learning, consistent with its role in adult memory integration21 and generalization.22 These results suggest that the hippocampus supports the vital ability of infants to extract the structure of their environment through experience.
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Affiliation(s)
- Cameron T Ellis
- Department of Psychology, Yale University, 2 Hillhouse Avenue, New Haven, CT 06511, USA
| | - Lena J Skalaban
- Department of Psychology, Yale University, 2 Hillhouse Avenue, New Haven, CT 06511, USA
| | - Tristan S Yates
- Department of Psychology, Yale University, 2 Hillhouse Avenue, New Haven, CT 06511, USA
| | - Vikranth R Bejjanki
- Department of Psychology, Hamilton College, 198 College Hill Road, Clinton, NY 13323, USA
| | - Natalia I Córdova
- Department of Psychology, Yale University, 2 Hillhouse Avenue, New Haven, CT 06511, USA
| | - Nicholas B Turk-Browne
- Department of Psychology, Yale University, 2 Hillhouse Avenue, New Haven, CT 06511, USA.
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Abstract
In mammals, the selective transformation of transient experience into stored memory occurs in the hippocampus, which develops representations of specific events in the context in which they occur. In this review, we focus on the development of hippocampal circuits and the self-organized dynamics embedded within them since the latter critically support the role of the hippocampus in learning and memory. We first discuss evidence that adult hippocampal cells and circuits are sculpted by development as early as during embryonic neurogenesis. We argue that these primary developmental programs provide a scaffold onto which later experience of the external world can be grafted. Next, we review the different sequences in the development of hippocampal cells and circuits at anatomical and functional levels. We cover a period extending from neurogenesis and migration to the appearance of phenotypic diversity within hippocampal cells, and their wiring into functional networks. We describe the progressive emergence of network dynamics in the hippocampus, from sensorimotor-driven early sharp waves to sequences of place cells tracking relational information. We outline the critical turn points and discontinuities in that developmental journey, and close by formulating open questions. We propose that rewinding the process of hippocampal development helps understand the main organization principles of memory circuits.
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Affiliation(s)
- Rosa Cossart
- Inserm, INMED, Turing Center for Living Systems, Aix Marseille University, Marseille, France
| | - Rustem Khazipov
- Inserm, INMED, Turing Center for Living Systems, Aix Marseille University, Marseille, France.,Laboratory of Neurobiology, Kazan Federal University, Kazan Russia
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44
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Han DH, Park P, Choi DI, Bliss TVP, Kaang BK. The essence of the engram: Cellular or synaptic? Semin Cell Dev Biol 2021; 125:122-135. [PMID: 34103208 DOI: 10.1016/j.semcdb.2021.05.033] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 05/28/2021] [Accepted: 05/31/2021] [Indexed: 10/21/2022]
Abstract
Memory is composed of various phases including cellular consolidation, systems consolidation, reconsolidation, and extinction. In the last few years it has been shown that simple association memories can be encoded by a subset of the neuronal population called engram cells. Activity of these cells is necessary and sufficient for the recall of association memory. However, it is unclear which molecular mechanisms allow cellular engrams to encode the diverse phases of memory. Further research is needed to examine the possibility that it is the synapses between engram cells (the synaptic engram) that constitute the memory. In this review we summarize recent findings on cellular engrams with a focus on different phases of memory, and discuss the distinct molecular mechanism required for cellular and synaptic engrams.
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Affiliation(s)
- Dae Hee Han
- School of Biological Sciences, College of Natural Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Pojeong Park
- School of Biological Sciences, College of Natural Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Dong Il Choi
- School of Biological Sciences, College of Natural Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Tim V P Bliss
- Group leader emeritus, The Francis Crick Institute, 1 Midland Rd, Somers Town, London NW1 1AT, UK
| | - Bong-Kiun Kaang
- School of Biological Sciences, College of Natural Sciences, Seoul National University, Seoul 08826, Republic of Korea.
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45
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Ryan TJ, Ortega-de San Luis C, Pezzoli M, Sen S. Engram cell connectivity: an evolving substrate for information storage. Curr Opin Neurobiol 2021; 67:215-225. [PMID: 33812274 DOI: 10.1016/j.conb.2021.01.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 01/15/2021] [Accepted: 01/16/2021] [Indexed: 01/02/2023]
Abstract
Understanding memory requires an explanation for how information can be stored in the brain in a stable state. The change in the brain that accounts for a given memory is referred to as an engram. In recent years, the term engram has been operationalized as the cells that are activated by a learning experience, undergoes plasticity, and are sufficient and necessary for memory recall. Using this framework, and a growing toolbox of related experimental techniques, engram manipulation has become a central topic in behavioral, systems, and molecular neuroscience. Recent research on the topic has provided novel insights into the mechanisms of long-term memory storage, and its overlap with instinct. We propose that memory and instinct may be embodied as isomorphic topological structures within the brain's microanatomical circuitry.
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Affiliation(s)
- Tomás J Ryan
- School of Biochemistry and Immunology and Trinity College Institute for Neuroscience, Trinity College Dublin, Dublin, D02 PN40, Ireland; Florey Institute of Neuroscience and Mental Health, Melbourne Brain Centre, University of Melbourne, Parkville, VIC 3052, Australia; Child & Brain Development Program, Canadian Institute for Advanced Research (CIFAR), Toronto, Ontario M5G 1M1, Canada.
| | - Clara Ortega-de San Luis
- School of Biochemistry and Immunology and Trinity College Institute for Neuroscience, Trinity College Dublin, Dublin, D02 PN40, Ireland
| | - Maurizio Pezzoli
- School of Biochemistry and Immunology and Trinity College Institute for Neuroscience, Trinity College Dublin, Dublin, D02 PN40, Ireland
| | - Siddhartha Sen
- Centre for Research on Adaptive Nanostructures and Nanodevices and School of Physics, Trinity College Dublin, D02 PN40, Ireland
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Bidirectional Regulation of Cognitive and Anxiety-like Behaviors by Dentate Gyrus Mossy Cells in Male and Female Mice. J Neurosci 2021; 41:2475-2495. [PMID: 33472828 DOI: 10.1523/jneurosci.1724-20.2021] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Revised: 12/04/2020] [Accepted: 01/04/2021] [Indexed: 02/08/2023] Open
Abstract
The dentate gyrus (DG) of the hippocampus is important for cognition and behavior. However, the circuits underlying these functions are unclear. DG mossy cells (MCs) are potentially important because of their excitatory synapses on the primary cell type, granule cells (GCs). However, MCs also activate GABAergic neurons, which inhibit GCs. We used viral delivery of designer receptors exclusively activated by designer drugs (DREADDs) in mice to implement a gain- and loss-of-function study of MCs in diverse behaviors. Using this approach, manipulations of MCs could bidirectionally regulate behavior. The results suggest that inhibiting MCs can reduce anxiety-like behavior and improve cognitive performance. However, not all cognitive or anxiety-related behaviors were influenced, suggesting specific roles of MCs in some, but not all, types of cognition and anxiety. Notably, several behaviors showed sex-specific effects, with females often showing more pronounced effects than the males. We also used the immediate early gene c-Fos to address whether DREADDs bidirectionally regulated MC or GC activity. We confirmed excitatory DREADDs increased MC c-Fos. However, there was no change in GC c-Fos, consistent with MC activation leading to GABAergic inhibition of GCs. In contrast, inhibitory DREADDs led to a large increase in GC c-Fos, consistent with a reduction in MC excitation of GABAergic neurons, and reduced inhibition of GCs. Together, these results suggest that MCs regulate anxiety and cognition in specific ways. We also raise the possibility that cognitive performance may be improved by reducing anxiety.SIGNIFICANCE STATEMENT The dentate gyrus (DG) has many important cognitive roles as well as being associated with affective behavior. This study addressed how a glutamatergic DG cell type called mossy cells (MCs) contributes to diverse behaviors, which is timely because it is known that MCs regulate the activity of the primary DG cell type, granule cells (GCs), but how MC activity influences behavior is unclear. We show, surprisingly, that activating MCs can lead to adverse behavioral outcomes, and inhibiting MCs have an opposite effect. Importantly, the results appeared to be task-dependent and showed that testing both sexes was important. Additional experiments indicated what MC and GC circuitry was involved. Together, the results suggest how MCs influence behaviors that involve the DG.
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Zawadzki P, Adamczyk AK. Personality and Authenticity in Light of the Memory-Modifying Potential of Optogenetics. AJOB Neurosci 2021; 12:3-21. [PMID: 33528319 DOI: 10.1080/21507740.2020.1866097] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
There has been a growing interest in research concerning memory modification technologies (MMTs) in recent years. Neuroscientists and psychologists are beginning to explore the prospect of controllable and intentional modification of human memory. One of the technologies with the greatest potential to this end is optogenetics-an invasive neuromodulation technique involving the use of light to control the activity of individual brain cells. It has recently shown the potential to modify specific long-term memories in animal models in ways not yet possible with other MMTs. As the therapeutic potential of optogenetics has already prompted approval of the first human trials, it is especially important and timely to consider the opportunities and dangers this technology may entail. In this article, we focus on possible consequences of optogenetics as an MMT by analyzing fundamental threats potentially associated with memory modifications: the potential disruption of personality and authenticity.
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48
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Bessières B, Cruz E, Alberini CM. Metabolomic profiling reveals a differential role for hippocampal glutathione reductase in infantile memory formation. eLife 2021; 10:68590. [PMID: 34825649 PMCID: PMC8626085 DOI: 10.7554/elife.68590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 11/09/2021] [Indexed: 01/12/2023] Open
Abstract
The metabolic mechanisms underlying the formation of early-life episodic memories remain poorly characterized. Here, we assessed the metabolomic profile of the rat hippocampus at different developmental ages both at baseline and following episodic learning. We report that the hippocampal metabolome significantly changes over developmental ages and that learning regulates differential arrays of metabolites according to age. The infant hippocampus had the largest number of significant changes following learning, with downregulation of 54 metabolites. Of those, a large proportion was associated with the glutathione-mediated cellular defenses against oxidative stress. Further biochemical, molecular, and behavioral assessments revealed that infantile learning evokes a rapid and persistent increase in the activity of neuronal glutathione reductase, the enzyme that regenerates reduced glutathione from its oxidized form. Inhibition of glutathione reductase selectively impaired long-term memory formation in infant but not in juvenile and adult rats, confirming its age-specific role. Thus, metabolomic profiling revealed that the hippocampal glutathione-mediated antioxidant pathway is differentially required for the formation of infantile memory.
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Affiliation(s)
| | - Emmanuel Cruz
- Center for Neural Science, New York UniversityNew YorkUnited States
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49
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The Ontogeny of Hippocampus-Dependent Memories. J Neurosci 2020; 41:920-926. [PMID: 33328296 DOI: 10.1523/jneurosci.1651-20.2020] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 10/16/2020] [Accepted: 10/20/2020] [Indexed: 11/21/2022] Open
Abstract
The formation of memories that contain information about the specific time and place of acquisition, which are commonly referred to as "autobiographical" or "episodic" memories, critically relies on the hippocampus and on a series of interconnected structures located in the medial temporal lobe of the mammalian brain. The observation that adults retain very few of these memories from the first years of their life has fueled a long-standing debate on whether infants can make the types of memories that in adults are processed by the hippocampus-dependent memory system, and whether the hippocampus is involved in learning and memory processes early in life. Recent evidence shows that, even at a time when its circuitry is not yet mature, the infant hippocampus is able to produce long-lasting memories. However, the ability to acquire and store such memories relies on molecular pathways and network-based activity dynamics different from the adult system, which mature with age. The mechanisms underlying the formation of hippocampus-dependent memories during infancy, and the role that experience exerts in promoting the maturation of the hippocampus-dependent memory system, remain to be understood. In this review, we discuss recent advances in our understanding of the ontogeny and the biological correlates of hippocampus-dependent memories.
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50
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Goode TD, Tanaka KZ, Sahay A, McHugh TJ. An Integrated Index: Engrams, Place Cells, and Hippocampal Memory. Neuron 2020; 107:805-820. [PMID: 32763146 PMCID: PMC7486247 DOI: 10.1016/j.neuron.2020.07.011] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 06/17/2020] [Accepted: 07/13/2020] [Indexed: 01/10/2023]
Abstract
The hippocampus and its extended network contribute to encoding and recall of episodic experiences. Drawing from recent anatomical, physiological, and behavioral studies, we propose that hippocampal engrams function as indices to mediate memory recall. We broaden this idea to discuss potential relationships between engrams and hippocampal place cells, as well as the molecular, cellular, physiological, and circuit determinants of engrams that permit flexible routing of information to intra- and extrahippocampal circuits for reinstatement, a feature critical to memory indexing. Incorporating indexing into frameworks of memory function opens new avenues of study and even therapies for hippocampal dysfunction.
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Affiliation(s)
- Travis D Goode
- Center for Regenerative Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Harvard Stem Cell Institute, Cambridge, MA 02138, USA; Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114 USA; Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
| | - Kazumasa Z Tanaka
- Memory Research Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Kunigami-gun, Okinawa, Japan
| | - Amar Sahay
- Center for Regenerative Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Harvard Stem Cell Institute, Cambridge, MA 02138, USA; Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114 USA; Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA.
| | - Thomas J McHugh
- Laboratory for Circuit and Behavioral Physiology, RIKEN Center for Brain Science, Wakoshi, Saitama, Japan.
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