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Thibeault KC, Leonard MZ, Kondev V, Emerson SD, Bethi R, Lopez AJ, Sens JP, Nabit BP, Elam HB, Winder DG, Patel S, Kiraly DD, Grueter BA, Calipari ES. A Cocaine-Activated Ensemble Exerts Increased Control Over Behavior While Decreasing in Size. Biol Psychiatry 2024:S0006-3223(24)01388-X. [PMID: 38901723 DOI: 10.1016/j.biopsych.2024.06.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 06/06/2024] [Accepted: 06/11/2024] [Indexed: 06/22/2024]
Abstract
BACKGROUND Substance use disorder is characterized by long-lasting changes in reward-related brain regions, such as the nucleus accumbens. Previous work has shown that cocaine exposure induces plasticity in broad, genetically defined cell types in the nucleus accumbens; however, in response to a stimulus, only a small percentage of neurons are transcriptionally active-termed an ensemble. Here, we identify an Arc-expressing neuronal ensemble that has a unique trajectory of recruitment and causally controls drug self-administration after repeated, but not acute, cocaine exposure. METHODS Using Arc-CreERT2 transgenic mice, we expressed transgenes in Arc+ ensembles activated by cocaine exposure (either acute [1 × 10 mg/kg intraperitoneally] or repeated [10 × 10 mg/kg intraperitoneally]). Using genetic, optical, and physiological recording and manipulation strategies, we assessed the contribution of these ensembles to behaviors associated with substance use disorder. RESULTS Repeated cocaine exposure reduced the size of the ensemble while simultaneously increasing its control over behavior. Neurons within the repeated cocaine ensemble were hyperexcitable, and their optogenetic excitation was sufficient for reinforcement. Finally, lesioning the repeated cocaine, but not the acute cocaine, ensemble blunted cocaine self-administration. Thus, repeated cocaine exposure reduced the size of the ensemble while simultaneously increasing its contributions to drug reinforcement. CONCLUSIONS We showed that repeated, but not acute, cocaine exposure induced a physiologically distinct ensemble characterized by the expression of the immediate early gene Arc, which was uniquely capable of modulating reinforcement behavior.
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Affiliation(s)
- Kimberly C Thibeault
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee; Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, Tennessee
| | - Michael Z Leonard
- Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, Tennessee; Department of Pharmacology, Vanderbilt University, Nashville, Tennessee
| | - Veronika Kondev
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee; Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, Tennessee
| | - Soren D Emerson
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee; Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, Tennessee
| | - Rishik Bethi
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee; Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, Tennessee
| | - Alberto J Lopez
- Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, Tennessee; Department of Pharmacology, Vanderbilt University, Nashville, Tennessee
| | - Jonathon P Sens
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, North Carolina
| | - Brett P Nabit
- Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, Tennessee; Department of Pharmacology, Vanderbilt University, Nashville, Tennessee
| | - Hannah B Elam
- Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, Tennessee; Department of Pharmacology, Vanderbilt University, Nashville, Tennessee
| | - Danny G Winder
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee; Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, Tennessee; Department of Pharmacology, Vanderbilt University, Nashville, Tennessee; Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee; Department of Psychiatry and Behavioral Sciences, Vanderbilt University Medical Center, Nashville, Tennessee; Vanderbilt JF Kennedy Center, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Sachin Patel
- Department of Psychiatry, Northwestern University, Chicago, Illinois
| | - Drew D Kiraly
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, North Carolina
| | - Brad A Grueter
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee; Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, Tennessee; Department of Pharmacology, Vanderbilt University, Nashville, Tennessee; Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee; Department of Psychiatry and Behavioral Sciences, Vanderbilt University Medical Center, Nashville, Tennessee; Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Erin S Calipari
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee; Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, Tennessee; Department of Pharmacology, Vanderbilt University, Nashville, Tennessee; Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee; Department of Psychiatry and Behavioral Sciences, Vanderbilt University Medical Center, Nashville, Tennessee; Vanderbilt JF Kennedy Center, Vanderbilt University School of Medicine, Nashville, Tennessee.
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2
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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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3
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Yadav N, Toader A, Rajasethupathy P. Beyond hippocampus: Thalamic and prefrontal contributions to an evolving memory. Neuron 2024; 112:1045-1059. [PMID: 38272026 DOI: 10.1016/j.neuron.2023.12.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 11/07/2023] [Accepted: 12/22/2023] [Indexed: 01/27/2024]
Abstract
The hippocampus has long been at the center of memory research, and rightfully so. However, with emerging technological capabilities, we can increasingly appreciate memory as a more dynamic and brain-wide process. In this perspective, our goal is to begin developing models to understand the gradual evolution, reorganization, and stabilization of memories across the brain after their initial formation in the hippocampus. By synthesizing studies across the rodent and human literature, we suggest that as memory representations initially form in hippocampus, parallel traces emerge in frontal cortex that cue memory recall, and as they mature, with sustained support initially from limbic then diencephalic then cortical circuits, they become progressively independent of hippocampus and dependent on a mature cortical representation. A key feature of this model is that, as time progresses, memory representations are passed on to distinct circuits with progressively longer time constants, providing the opportunity to filter, forget, update, or reorganize memories in the process of committing to long-term storage.
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Affiliation(s)
- Nakul Yadav
- Laboratory of Neural Dynamics & Cognition, The Rockefeller University, New York, NY, USA
| | - Andrew Toader
- Laboratory of Neural Dynamics & Cognition, The Rockefeller University, New York, NY, USA
| | - Priya Rajasethupathy
- Laboratory of Neural Dynamics & Cognition, The Rockefeller University, New York, NY, USA.
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4
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McGowan JC, Ladner LR, Shubeck CX, Tapia J, LaGamma CT, Anqueira-González A, DeFrancesco A, Chen BK, Hunsberger HC, Sydnor EJ, Logan RW, Yu TS, Kernie SG, Denny CA. Traumatic Brain Injury-Induced Fear Generalization in Mice Involves Hippocampal Memory Trace Dysfunction and Is Alleviated by (R,S)-Ketamine. Biol Psychiatry 2024; 95:15-26. [PMID: 37423591 PMCID: PMC10772211 DOI: 10.1016/j.biopsych.2023.06.030] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 06/12/2023] [Accepted: 06/29/2023] [Indexed: 07/11/2023]
Abstract
BACKGROUND Traumatic brain injury (TBI) is a debilitating neurological disorder caused by an impact to the head by an outside force. TBI results in persistent cognitive impairments, including fear generalization and the inability to distinguish between aversive and neutral stimuli. The mechanisms underlying fear generalization have not been fully elucidated, and there are no targeted therapeutics to alleviate this symptom of TBI. METHODS To identify the neural ensembles mediating fear generalization, we utilized ArcCreERT2 × enhanced yellow fluorescent protein (EYFP) mice, which allow for activity-dependent labeling and quantification of memory traces. Mice were administered a sham surgery or the controlled cortical impact model of TBI. Mice were then administered a contextual fear discrimination paradigm and memory traces were quantified in numerous brain regions. In a separate group of mice, we tested if (R,S)-ketamine could decrease fear generalization and alter the corresponding memory traces in TBI mice. RESULTS TBI mice exhibited increased fear generalization when compared with sham mice. This behavioral phenotype was paralleled by altered memory traces in the dentate gyrus, CA3, and amygdala, but not by alterations in inflammation or sleep. In TBI mice, (R,S)-ketamine facilitated fear discrimination, and this behavioral improvement was reflected in dentate gyrus memory trace activity. CONCLUSIONS These data show that TBI induces fear generalization by altering fear memory traces and that this deficit can be improved with a single injection of (R,S)-ketamine. This work enhances our understanding of the neural basis of TBI-induced fear generalization and reveals potential therapeutic avenues for alleviating this symptom.
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Affiliation(s)
- Josephine C McGowan
- Doctoral Program in Neurobiology and Behavior, Columbia University, New York, New York.
| | | | | | | | - Christina T LaGamma
- Division of Systems Neuroscience, Research Foundation for Mental Hygiene, Inc./New York State Psychiatric Institute, New York, New York; Department of Psychiatry, Columbia University Irving Medical Center, New York, New York
| | | | - Ariana DeFrancesco
- Department of Behavioral Neuroscience, Queens College, New York, New York
| | - Briana K Chen
- Division of Systems Neuroscience, Research Foundation for Mental Hygiene, Inc./New York State Psychiatric Institute, New York, New York; Department of Psychiatry, Columbia University Irving Medical Center, New York, New York
| | - Holly C Hunsberger
- Center for Neurodegenerative Diseases and Therapeutics, Rosalind Franklin University of Medicine and Science, Chicago Medical School, Chicago, Illinois
| | - Ezra J Sydnor
- Division of Systems Neuroscience, Research Foundation for Mental Hygiene, Inc./New York State Psychiatric Institute, New York, New York
| | - Ryan W Logan
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, Massachusetts; Department of Psychiatry, University of Massachusetts Chan Medical School, Worcester, Massachusetts
| | - Tzong-Shiue Yu
- Department of Pediatrics, Columbia University College of Physicians and Surgeons, New York, New York
| | - Steven G Kernie
- Department of Pediatrics, Columbia University College of Physicians and Surgeons, New York, New York; Department of Neurology, Columbia University College of Physicians and Surgeons, New York, New York
| | - Christine A Denny
- Division of Systems Neuroscience, Research Foundation for Mental Hygiene, Inc./New York State Psychiatric Institute, New York, New York; Department of Psychiatry, Columbia University Irving Medical Center, New York, New York.
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5
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Jung JH, Wang Y, Rashid AJ, Zhang T, Frankland PW, Josselyn SA. Examining memory linking and generalization using scFLARE2, a temporally precise neuronal activity tagging system. Cell Rep 2023; 42:113592. [PMID: 38103203 PMCID: PMC10842737 DOI: 10.1016/j.celrep.2023.113592] [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: 08/28/2023] [Revised: 10/26/2023] [Accepted: 11/30/2023] [Indexed: 12/18/2023] Open
Abstract
How memories are organized in the brain influences whether they are remembered discretely versus linked with other experiences or whether generalized information is applied to entirely novel situations. Here, we used scFLARE2 (single-chain fast light- and activity-regulated expression 2), a temporally precise tagging system, to manipulate mouse lateral amygdala neurons active during one of two 3 min threat experiences occurring close (3 h) or further apart (27 h) in time. Silencing scFLARE2-tagged neurons showed that two threat experiences occurring at distal times are dis-allocated to orthogonal engram ensembles and remembered discretely, whereas the same two threat experiences occurring in close temporal proximity are linked via co-allocation to overlapping engram ensembles. Moreover, we found that co-allocation mediates memory generalization applied to a completely novel stimulus. These results indicate that endogenous temporal evolution of engram ensemble neuronal excitability determines how memories are organized and remembered and that this would not be possible using conventional immediate-early gene-based tagging methods.
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Affiliation(s)
- Jung Hoon Jung
- Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada
| | - Ying Wang
- Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Asim J Rashid
- Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada
| | - Tao Zhang
- Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada
| | - Paul W Frankland
- Program in Neurosciences & Mental Health, Hospital for Sick Children, 555 University Avenue, 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 Avenue, 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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6
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Salery M, Godino A, Xu YQ, Fullard JF, Durand-de Cuttoli R, LaBanca AR, Holt LM, Russo SJ, Roussos P, Nestler EJ. Transcriptional correlates of cocaine-associated learning in striatal ARC ensembles. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.13.571585. [PMID: 38168167 PMCID: PMC10760161 DOI: 10.1101/2023.12.13.571585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Learned associations between the rewarding effects of drugs and the context in which they are experienced underlie context-induced relapse. Previous work demonstrates the importance of sparse neuronal populations - called neuronal ensembles - in associative learning and cocaine seeking, but it remains unknown whether the encoding vs. retrieval of cocaine-associated memories involves similar or distinct mechanisms of ensemble activation and reactivation in nucleus accumbens (NAc). We use ArcCreER T2 mice to establish that mostly distinct NAc ensembles are recruited by initial vs. repeated exposures to cocaine, which are then differentially reactivated and exert distinct effects during cocaine-related memory retrieval. Single-nuclei RNA-sequencing of these ensembles demonstrates predominant recruitment of D1 medium spiny neurons and identifies transcriptional properties that are selective to cocaine-recruited NAc neurons and could explain distinct excitability features. These findings fundamentally advance our understanding of how cocaine drives pathological memory formation during repeated exposures.
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7
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Masi M. An evidence-based critical review of the mind-brain identity theory. Front Psychol 2023; 14:1150605. [PMID: 37965649 PMCID: PMC10641890 DOI: 10.3389/fpsyg.2023.1150605] [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: 01/24/2023] [Accepted: 09/18/2023] [Indexed: 11/16/2023] Open
Abstract
In the philosophy of mind, neuroscience, and psychology, the causal relationship between phenomenal consciousness, mentation, and brain states has always been a matter of debate. On the one hand, material monism posits consciousness and mind as pure brain epiphenomena. One of its most stringent lines of reasoning relies on a 'loss-of-function lesion premise,' according to which, since brain lesions and neurochemical modifications lead to cognitive impairment and/or altered states of consciousness, there is no reason to doubt the mind-brain identity. On the other hand, dualism or idealism (in one form or another) regard consciousness and mind as something other than the sole product of cerebral activity pointing at the ineffable, undefinable, and seemingly unphysical nature of our subjective qualitative experiences and its related mental dimension. Here, several neuroscientific findings are reviewed that question the idea that posits phenomenal experience as an emergent property of brain activity, and argue that the premise of material monism is based on a logical correlation-causation fallacy. While these (mostly ignored) findings, if considered separately from each other, could, in principle, be recast into a physicalist paradigm, once viewed from an integral perspective, they substantiate equally well an ontology that posits mind and consciousness as a primal phenomenon.
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Affiliation(s)
- Marco Masi
- Independent Researcher, Knetzgau, Germany
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8
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Robins S. The 21st century engram. WILEY INTERDISCIPLINARY REVIEWS. COGNITIVE SCIENCE 2023; 14:e1653. [PMID: 37177850 DOI: 10.1002/wcs.1653] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 04/10/2023] [Accepted: 04/22/2023] [Indexed: 05/15/2023]
Abstract
The search for the engram-the neural mechanism of memory-has been a guiding research project for neuroscience since its emergence as a distinct scientific field. Recent developments in the tools and techniques available for investigating the mechanisms of memory have allowed researchers to proclaimed the search is over. While there is ongoing debate about the justification for that claim, renewed interest in the engram is clear. This attention highlights the impoverished status of the engram concept. As research accelerates, the simple characterization of the engram as an enduring physical change is stretched thin. Now that the engram commitment has been made more explicit, it must also be made more precise. If the project of 20th century neurobiology was finding the engram, the project of the 21st must be supplying a richer account of what's been found. This paper sketches a history of the engram, and a way forward. This article is categorized under: Philosophy > Foundations of Cognitive Science.
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Affiliation(s)
- Sarah Robins
- Department of Philosophy, University of Kansas, Lawrence, Kansas, USA
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9
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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: 17] [Impact Index Per Article: 17.0] [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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10
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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: 14] [Impact Index Per Article: 14.0] [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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11
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Leal Santos S, Chen BK, Pereira GR, Pham V, Denny CA. Propranolol Administration Modulates Neural Activity in the Hippocampal Hilus During Fear Retrieval. Front Behav Neurosci 2022; 16:919831. [PMID: 35874651 PMCID: PMC9301278 DOI: 10.3389/fnbeh.2022.919831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 06/13/2022] [Indexed: 11/23/2022] Open
Abstract
Altered fear learning is a strong behavioral component of anxiety disorders such as post-traumatic stress disorder (PTSD). Recent efforts have attempted to combine exposure therapies with drugs that target fear memory retrieval and memory reconsolidation, in order to improve treatment efficacy. The noradrenergic (NA) signaling system is of particular interest, due to its role in regulating the stress response and its involvement in fear and learning processes. Importantly, propranolol (P), a non-selective β-adrenergic antagonist, has shown the potential in decreasing exaggerated fear in both humans and animal models. In a previous study, we utilized an activity-dependent tagging murine model to determine the neural mechanisms by which propranolol attenuates learned fear. We found that propranolol acutely decreased memory trace reactivation specifically in the dorsal dentate gyrus (dDG), but not in CA3 or CA1. Here, we extended our previous study by investigating whether propranolol additionally altered activity in the hilus, a polymorphic layer that consists of neurons, mossy cells, and GABAergic interneurons. We found that propranolol acutely reduced overall hilar activity in both the dorsal and ventral hilus. Moreover, we report that propranolol significantly altered the activity of parvalbumin (PV)+ cells in the ventral (vDG), but not dorsal DG (dDG). Together, these results suggest that a β-adrenergic blockade may affect the activity of excitatory and inhibitory cell types in the hilar layer of the DG, and that these alterations may contribute to manipulating fear memory traces.
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Affiliation(s)
- Sofia Leal Santos
- Department of Psychiatry, Columbia University Irving Medical Center, New York, NY, United States
- Division of Systems Neuroscience, Research Foundation for Mental Hygiene, Inc. (RFMH)/New York State Psychiatric Institute (NYSPI), New York, NY, United States
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal
- Instituto de Investigação em Ciências da Vida e da Saúde (ICVS)/3Bs - PT Government Associate Laboratory, Guimarães, Portugal
| | - Briana K. Chen
- Neurobiology and Behavior (NB&B) Graduate Program, Columbia University, New York, NY, United States
| | - Guilherme R. Pereira
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal
- Instituto de Investigação em Ciências da Vida e da Saúde (ICVS)/3Bs - PT Government Associate Laboratory, Guimarães, Portugal
| | - Vananh Pham
- Department of Psychiatry, Columbia University Irving Medical Center, New York, NY, United States
- Division of Systems Neuroscience, Research Foundation for Mental Hygiene, Inc. (RFMH)/New York State Psychiatric Institute (NYSPI), New York, NY, United States
| | - Christine A. Denny
- Department of Psychiatry, Columbia University Irving Medical Center, New York, NY, United States
- Division of Systems Neuroscience, Research Foundation for Mental Hygiene, Inc. (RFMH)/New York State Psychiatric Institute (NYSPI), New York, NY, United States
- *Correspondence: Christine A. Denny,
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12
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Marks WD, Yokose J, Kitamura T, Ogawa SK. Neuronal Ensembles Organize Activity to Generate Contextual Memory. Front Behav Neurosci 2022; 16:805132. [PMID: 35368306 PMCID: PMC8965349 DOI: 10.3389/fnbeh.2022.805132] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 02/14/2022] [Indexed: 11/17/2022] Open
Abstract
Contextual learning is a critical component of episodic memory and important for living in any environment. Context can be described as the attributes of a location that are not the location itself. This includes a variety of non-spatial information that can be derived from sensory systems (sounds, smells, lighting, etc.) and internal state. In this review, we first address the behavioral underpinnings of contextual memory and the development of context memory theory, with a particular focus on the contextual fear conditioning paradigm as a means of assessing contextual learning and the underlying processes contributing to it. We then present the various neural centers that play roles in contextual learning. We continue with a discussion of the current knowledge of the neural circuitry and physiological processes that underlie contextual representations in the Entorhinal cortex-Hippocampal (EC-HPC) circuit, as the most well studied contributor to contextual memory, focusing on the role of ensemble activity as a representation of context with a description of remapping, and pattern separation and completion in the processing of contextual information. We then discuss other critical regions involved in contextual memory formation and retrieval. We finally consider the engram assembly as an indicator of stored contextual memories and discuss its potential contribution to contextual memory.
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Affiliation(s)
- William D. Marks
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Jun Yokose
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Takashi Kitamura
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Sachie K. Ogawa
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, United States
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13
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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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14
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Marks WD, Yamamoto N, Kitamura T. Complementary roles of differential medial entorhinal cortex inputs to the hippocampus for the formation and integration of temporal and contextual memory (Systems Neuroscience). Eur J Neurosci 2021; 54:6762-6779. [PMID: 32277786 PMCID: PMC8187108 DOI: 10.1111/ejn.14737] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 03/28/2020] [Accepted: 03/30/2020] [Indexed: 11/29/2022]
Abstract
In humans and rodents, the entorhinal cortical (EC)-hippocampal (HPC) circuit is crucial for the formation and recall of memory, preserving both spatial information and temporal information about the occurrence of past events. Both modeling and experimental studies have revealed circuits within this network that play crucial roles in encoding space and context. However, our understanding about the time-related aspects of memory is just beginning to be understood. In this review, we first describe updates regarding recent anatomical discoveries for the EC-HPC network, as several important neural circuits critical for memory formation have been discovered by newly developed neural tracing technologies. Second, we examine the complementary roles of multiple medial entorhinal cortical inputs, including newly discovered circuits, into the hippocampus for the temporal and spatial aspects of memory. Finally, we will discuss how temporal and contextual memory information is integrated in HPC cornu ammonis 1 cells. We provide new insights into the neural circuit mechanisms for anatomical and functional segregation and integration of the temporal and spatial aspects of memory encoding in the EC-HPC networks.
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Affiliation(s)
- William D. Marks
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, 75390, USA
| | - Naoki Yamamoto
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, 75390, USA
| | - Takashi Kitamura
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, 75390, USA
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, Texas, 75390, USA
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15
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Cummings KA, Lacagnina AF, Clem RL. GABAergic microcircuitry of fear memory encoding. Neurobiol Learn Mem 2021; 184:107504. [PMID: 34425220 DOI: 10.1016/j.nlm.2021.107504] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 08/12/2021] [Accepted: 08/15/2021] [Indexed: 12/30/2022]
Abstract
The paradigm of fear conditioning is largely responsible for our current understanding of how memories are encoded at the cellular level. Its most fundamental underlying mechanism is considered to be plasticity of synaptic connections between excitatory projection neurons (PNs). However, recent studies suggest that while PNs execute critical memory functions, their activity at key stages of learning and recall is extensively orchestrated by a diverse array of GABAergic interneurons (INs). Here we review the contributions of genetically-defined INs to processing of threat-related stimuli in fear conditioning, with a particular focus on how synaptic interactions within interconnected networks of INs modulates PN activity through both inhibition and disinhibition. Furthermore, we discuss accumulating evidence that GABAergic microcircuits are an important locus for synaptic plasticity during fear learning and therefore a viable substrate for long-term memory. These findings suggest that further investigation of INs could unlock unique conceptual insights into the organization and function of fear memory networks.
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Affiliation(s)
- Kirstie A Cummings
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States; Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States; Department of Neurobiology, University of Alabama Birmingham School of Medicine, Birmingham, AL 35294, United States
| | - Anthony F Lacagnina
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States; Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Roger L Clem
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States; Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States.
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16
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Leal Santos S, Stackmann M, Muñoz Zamora A, Mastrodonato A, De Landri AV, Vaughan N, Chen BK, Lanio M, Denny CA. Propranolol Decreases Fear Expression by Modulating Fear Memory Traces. Biol Psychiatry 2021; 89:1150-1161. [PMID: 33766406 PMCID: PMC8201901 DOI: 10.1016/j.biopsych.2021.01.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 01/11/2021] [Accepted: 01/12/2021] [Indexed: 01/27/2023]
Abstract
BACKGROUND Posttraumatic stress disorder can develop after a traumatic event and results in heightened, inappropriate fear and anxiety. Although approximately 8% of the U.S. population is affected by posttraumatic stress disorder, only two drugs have been approved by the Food and Drug Administration to treat it, both with limited efficacy. Propranolol, a nonselective β-adrenergic antagonist, has shown efficacy in decreasing exaggerated fear, and there has been renewed interest in using it to treat fear disorders. METHODS Here, we sought to determine the mechanisms by which propranolol attenuates fear by utilizing an activity-dependent tagging system, ArcCreERT2 x eYFP mice. 129S6/SvEv mice were administered a 4-shock contextual fear conditioning paradigm followed by immediate or delayed context reexposures. Saline or propranolol was administered either before or after the first context reexposure. To quantify hippocampal, prefrontal, and amygdalar memory traces, ArcCreERT2 x eYFP mice were administered a delayed context reexposure with either a saline or propranolol injection before context reexposure. RESULTS Propranolol decreased fear expression only when administered before a delayed context reexposure. Fear memory traces were affected in the dorsal dentate gyrus and basolateral amygdala after propranolol administration in the ArcCreERT2 x eYFP mice. Propranolol acutely altered functional connectivity between the hippocampal, cortical, and amygdalar regions. CONCLUSIONS These data indicate that propranolol may decrease fear expression by altering network-correlated activity and by weakening the reactivation of the initial traumatic memory trace. This work contributes to the understanding of noradrenergic drugs as therapeutic aids for patients with posttraumatic stress disorder.
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Affiliation(s)
- Sofia Leal Santos
- Department of Psychiatry, Columbia University Irving Medical Center, New York, New York; Division of Systems Neuroscience, Research Foundation for Mental Hygiene Inc/New York State Psychiatric Institute, New York, New York; Life and Health Sciences Research Institute, School of Medicine, University of Minho, Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga, Portugal
| | - Michelle Stackmann
- Neurobiology and Behavior Graduate Program, Columbia University, New York, New York
| | - Andrea Muñoz Zamora
- Division of Systems Neuroscience, Research Foundation for Mental Hygiene Inc/New York State Psychiatric Institute, New York, New York
| | - Alessia Mastrodonato
- Department of Psychiatry, Columbia University Irving Medical Center, New York, New York; Division of Systems Neuroscience, Research Foundation for Mental Hygiene Inc/New York State Psychiatric Institute, New York, New York
| | - Allegra V De Landri
- Division of Systems Neuroscience, Research Foundation for Mental Hygiene Inc/New York State Psychiatric Institute, New York, New York; Columbia College, Columbia University, New York, New York
| | - Nick Vaughan
- Columbia College, Columbia University, New York, New York
| | - Briana K Chen
- Neurobiology and Behavior Graduate Program, Columbia University, New York, New York
| | - Marcos Lanio
- Medical Scientist Training Program, Columbia University Irving Medical Center, New York, New York; Neurobiology and Behavior Graduate Program, Columbia University, New York, New York
| | - Christine A Denny
- Department of Psychiatry, Columbia University Irving Medical Center, New York, New York; Division of Systems Neuroscience, Research Foundation for Mental Hygiene Inc/New York State Psychiatric Institute, New York, New York.
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17
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Neuronal ensembles in memory processes. Semin Cell Dev Biol 2021; 125:136-143. [PMID: 33858772 DOI: 10.1016/j.semcdb.2021.04.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 03/30/2021] [Accepted: 04/01/2021] [Indexed: 12/19/2022]
Abstract
A neuronal ensemble represents the concomitant activity of a specific group of neurons that could encompass a broad repertoire of brain functions such as motor, perceptual, memory or cognitive states. On the other hand, a memory engram portrays the physical manifestation of memory or the changes that enable learning and retrieval. Engram studies focused for many years on finding where memories are stored as in, which cells or brain regions represent a memory trace, and disregarded the investigation of how neuronal activity patterns give rise to such memories. Recent experiments suggest that the association and reactivation of specific neuronal groups could be the main mechanism underlying the brain's ability to remember past experiences and envision future actions. Thus, the growing consensus is that the interaction between neuronal ensembles could allow sequential activity patterns to become memories and recurrent memories to compose complex behaviors. The goal of this review is to propose how the neuronal ensemble framework could be translated and useful to understand memory processes.
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18
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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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19
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Salery M, Godino A, Nestler EJ. Drug-activated cells: From immediate early genes to neuronal ensembles in addiction. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2021; 90:173-216. [PMID: 33706932 DOI: 10.1016/bs.apha.2020.09.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Beyond their rapid rewarding effects, drugs of abuse can durably alter an individual's response to their environment as illustrated by the compulsive drug seeking and risk of relapse triggered by drug-associated stimuli. The persistence of these associations even long after cessation of drug use demonstrates the enduring mark left by drugs on brain reward circuits. However, within these circuits, neuronal populations are differently affected by drug exposure and growing evidence indicates that relatively small subsets of neurons might be involved in the encoding and expression of drug-mediated associations. The identification of sparse neuronal populations recruited in response to drug exposure has benefited greatly from the study of immediate early genes (IEGs) whose induction is critical in initiating plasticity programs in recently activated neurons. In particular, the development of technologies to manipulate IEG-expressing cells has been fundamental to implicate broadly distributed neuronal ensembles coincidently activated by either drugs or drug-associated stimuli and to then causally establish their involvement in drug responses. In this review, we summarize the literature regarding IEG regulation in different learning paradigms and addiction models to highlight their role as a marker of activity and plasticity. As the exploration of neuronal ensembles in addiction improves our understanding of drug-associated memory encoding, it also raises several questions regarding the cellular and molecular characteristics of these discrete neuronal populations as they become incorporated in drug-associated neuronal ensembles. We review recent efforts towards this goal and discuss how they will offer a more comprehensive understanding of addiction pathophysiology.
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Affiliation(s)
- Marine Salery
- Nash Family Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Arthur Godino
- Nash Family Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Eric J Nestler
- Nash Family Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States.
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20
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Mechanism of seizure-induced retrograde amnesia. Prog Neurobiol 2020; 200:101984. [PMID: 33388373 DOI: 10.1016/j.pneurobio.2020.101984] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 12/09/2020] [Accepted: 12/22/2020] [Indexed: 11/21/2022]
Abstract
Seizures cause retrograde amnesia, but underlying mechanisms are poorly understood. We tested whether seizure activated neuronal circuits overlap with spatial memory engram and whether seizures saturate LTP in engram cells. A seizure caused retrograde amnesia for spatial memory task. Spatial learning and a seizure caused cFos expression and synaptic plasticity overlapping set of neurons in the CA1 of the hippocampus. Recordings from learning-labeled CA1 pyramidal neurons showed potentiated synapses. Seizure-tagged neurons were also more excitable with larger rectifying excitatory postsynaptic currents than surrounding unlabeled neurons. These neurons had enlarged dendritic spines and saturated LTP. A seizure immediately after learning, reset the memory engram. Seizures cause retrograde amnesia through shared ensembles and mechanisms.
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21
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Sullivan KE, Kendrick RM, Cembrowski MS. Elucidating memory in the brain via single-cell transcriptomics. J Neurochem 2020; 157:982-992. [PMID: 33230878 DOI: 10.1111/jnc.15250] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Revised: 11/17/2020] [Accepted: 11/19/2020] [Indexed: 01/17/2023]
Abstract
Elucidating the neural mechanisms of memory in the brain is a central goal of neuroscience. Here, we discuss modern-day transcriptomics methodologies, and how they are well-poised to revolutionize our insight into memory mechanisms at unprecedented resolution and throughput. Focusing on the hippocampus and amygdala, two regions extensively examined in memory research, we show how single-cell transcriptomics technologies have been leveraged to understand the naïve state of these brain regions. Building upon this foundation, we show that these technologies can be applied to single-trial learning paradigms to comprehensively identify molecules and cells that participate in the encoding and retrieval of memory. Transcriptomics also provides an opportunity to understand the cell-type organization of the human hippocampus and amygdala, and due to conservation of these brain regions between humans and rodents, to infer behavioral and causal contributions in the human brain by leveraging rodent cell-type homologies and interventions. Ultimately, such transcriptomic technologies are poised to usher in a qualitatively novel understanding of memory in the brain.
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Affiliation(s)
- Kaitlin E Sullivan
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, Canada
| | - Rennie M Kendrick
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, Canada
| | - Mark S Cembrowski
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, Canada.,School of Biomedical Engineering, University of British Columbia, Vancouver, Canada.,Institute of Applied Mathematics, University of British Columbia, Vancouver, Canada
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22
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Leblanc H, Ramirez S. Linking Social Cognition to Learning and Memory. J Neurosci 2020; 40:8782-8798. [PMID: 33177112 PMCID: PMC7659449 DOI: 10.1523/jneurosci.1280-20.2020] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 09/30/2020] [Accepted: 10/02/2020] [Indexed: 12/16/2022] Open
Abstract
Many mammals have evolved to be social creatures. In humans, the ability to learn from others' experiences is essential to survival; and from an early age, individuals are surrounded by a social environment that helps them develop a variety of skills, such as walking, talking, and avoiding danger. Similarly, in rodents, behaviors, such as food preference, exploration of novel contexts, and social approach, can be learned through social interaction. Social encounters facilitate new learning and help modify preexisting memories throughout the lifespan of an organism. Moreover, social encounters can help buffer stress or the effects of negative memories, as well as extinguish maladaptive behaviors. Given the importance of such interactions, there has been increasing work studying social learning and applying its concepts in a wide range of fields, including psychotherapy and medical sociology. The process of social learning, including its neural and behavioral mechanisms, has also been a rapidly growing field of interest in neuroscience. However, the term "social learning" has been loosely applied to a variety of psychological phenomena, often without clear definition or delineations. Therefore, this review gives a definition for specific aspects of social learning, provides an overview of previous work at the circuit, systems, and behavioral levels, and finally, introduces new findings on the social modulation of learning. We contextualize such social processes in the brain both through the role of the hippocampus and its capacity to process "social engrams" as well as through the brainwide realization of social experiences. With the integration of new technologies, such as optogenetics, chemogenetics, and calcium imaging, manipulating social engrams will likely offer a novel therapeutic target to enhance the positive buffering effects of social experiences or to inhibit fear-inducing social stimuli in models of anxiety and post-traumatic stress disorder.
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Affiliation(s)
- Heloise Leblanc
- Department of Psychological and Brain Sciences, Boston University, Boston, Massachusetts, 02119
- Boston University School of Medicine, Boston, Massachusetts, 02118
| | - Steve Ramirez
- Department of Psychological and Brain Sciences, Boston University, Boston, Massachusetts, 02119
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, 02119
- Neurophotonics Center at Boston University, Boston, Massachusetts, 02119
- Center for Systems Neuroscience at Boston University, Boston, Massachusetts, 02119
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23
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Morales C, Morici JF, Miranda M, Gallo FT, Bekinschtein P, Weisstaub NV. Neurophotonics Approaches for the Study of Pattern Separation. Front Neural Circuits 2020; 14:26. [PMID: 32587504 PMCID: PMC7298152 DOI: 10.3389/fncir.2020.00026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 04/20/2020] [Indexed: 11/26/2022] Open
Abstract
Successful memory involves not only remembering over time but also keeping memories distinct. Computational models suggest that pattern separation appears as a highly efficient process to discriminate between overlapping memories. Furthermore, lesion studies have shown that the dentate gyrus (DG) participates in pattern separation. However, these manipulations did not allow identifying the neuronal mechanism underlying pattern separation. The development of different neurophotonics techniques, together with other genetic tools, has been useful for the study of the microcircuit involved in this process. It has been shown that less-overlapped information would generate distinct neuronal representations within the granule cells (GCs). However, because glutamatergic or GABAergic cells in the DG are not functionally or structurally homogeneous, identifying the specific role of the different subpopulations remains elusive. Then, understanding pattern separation requires the ability to manipulate a temporal and spatially specific subset of cells in the DG and ideally to analyze DG cells activity in individuals performing a pattern separation dependent behavioral task. Thus, neurophotonics and calcium imaging techniques in conjunction with activity-dependent promoters and high-resolution microscopy appear as important tools for this endeavor. In this work, we review how different neurophotonics techniques have been implemented in the elucidation of a neuronal network that supports pattern separation alone or in combination with traditional techniques. We discuss the limitation of these techniques and how other neurophotonic techniques could be used to complement the advances presented up to this date.
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Affiliation(s)
- Cristian Morales
- Departamento de Psiquiatria, Centro Interdisciplinario de Neurociencia, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Juan Facundo Morici
- Instituto de Neurociencias Cognitiva y Traslacional (INCYT), Concejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Instituto de Neurología Cognitiva (INECO), Universidad Favaloro, Buenos Aires, Argentina
| | - Magdalena Miranda
- Instituto de Neurociencias Cognitiva y Traslacional (INCYT), Concejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Instituto de Neurología Cognitiva (INECO), Universidad Favaloro, Buenos Aires, Argentina
| | - Francisco Tomás Gallo
- Instituto de Neurociencias Cognitiva y Traslacional (INCYT), Concejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Instituto de Neurología Cognitiva (INECO), Universidad Favaloro, Buenos Aires, Argentina
| | - Pedro Bekinschtein
- Instituto de Neurociencias Cognitiva y Traslacional (INCYT), Concejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Instituto de Neurología Cognitiva (INECO), Universidad Favaloro, Buenos Aires, Argentina
| | - Noelia V. Weisstaub
- Instituto de Neurociencias Cognitiva y Traslacional (INCYT), Concejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Instituto de Neurología Cognitiva (INECO), Universidad Favaloro, Buenos Aires, Argentina
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24
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Gutzeit VA, Ahuna K, Santos TL, Cunningham AM, Sadsad Rooney M, Muñoz Zamora A, Denny CA, Donaldson ZR. Optogenetic reactivation of prefrontal social neural ensembles mimics social buffering of fear. Neuropsychopharmacology 2020; 45:1068-1077. [PMID: 32035426 PMCID: PMC7162965 DOI: 10.1038/s41386-020-0631-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 01/23/2020] [Accepted: 01/28/2020] [Indexed: 12/12/2022]
Abstract
Social buffering occurs when the presence of a companion attenuates the physiological and/or behavioral effects of a stressful or fear-provoking event. It represents a way in which social interactions can immediately and potently modulate behavior. As such, social buffering is one mechanism by which strong social support increases resilience to mental illness. Although the behavioral and neuroendocrine impacts of social buffering are well studied in multiple species, including humans, the neuronal underpinnings of this behavioral phenomenon remain largely unexplored. Previous work has shown that the infralimbic prefrontal cortex (IL-PFC) is important for processing social information and, in separate studies, for modulating fear and anxiety. Thus, we hypothesized that socially active cells within the IL-PFC may integrate social information to modulate fear responsivity. To test this hypothesis, we employed social buffering paradigms in male and female mice. Similar to prior studies in rats, we found that the presence of a cagemate reduced freezing in fear- and anxiety-provoking contexts. In accordance with previous work, we demonstrated that interaction with a novel or familiar conspecific induces activity in the IL-PFC as evidenced by increased immediate early gene (IEG) expression. We then utilized an activity-dependent tagging murine line, the ArcCreERT2 mice, to express channelrhodopsin (ChR2) in neurons active during the social encoding of a new cagemate. We found that optogenetic reactivation of these socially active neuronal ensembles phenocopied the effects of cagemate presence in male and female mice in learned and innate fear contexts without being inherently rewarding or altering locomotion. These data suggest that a social neural ensemble within the IL-PFC may contribute to social buffering of fear. These neurons may represent a novel therapeutic target for fear and anxiety disorders.
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Affiliation(s)
- Vanessa A. Gutzeit
- 000000041936877Xgrid.5386.8Neuroscience Graduate Program, Weill Cornell Graduate School of Medical Sciences, New York, NY 10065 USA
| | - Kylia Ahuna
- 0000000096214564grid.266190.aDepartment of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO 80309 USA
| | - Tabia L. Santos
- Zucker School of Medicine at Hofstra/Northwell, Hempstead, NY 11549 USA
| | - Ashley M. Cunningham
- 0000 0001 0670 2351grid.59734.3cMt. Sinai School of Medicine, New York, NY 10029 USA
| | | | - Andrea Muñoz Zamora
- 0000000419368729grid.21729.3fDepartment of Psychiatry, Columbia University Irving Medical Center (CUIMC), New York, NY 10032 USA ,0000 0000 8499 1112grid.413734.6Division of Systems Neuroscience, New York State Psychiatric Institute (NYSPI)/Research Foundation for Mental Hygiene, Inc. (RFMH), New York, NY 10032 USA
| | - Christine A. Denny
- 0000000419368729grid.21729.3fDepartment of Psychiatry, Columbia University Irving Medical Center (CUIMC), New York, NY 10032 USA ,0000 0000 8499 1112grid.413734.6Division of Systems Neuroscience, New York State Psychiatric Institute (NYSPI)/Research Foundation for Mental Hygiene, Inc. (RFMH), New York, NY 10032 USA
| | - Zoe R. Donaldson
- 0000000096214564grid.266190.aDepartment of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO 80309 USA ,0000000096214564grid.266190.aDepartment of Molecular, Cellular and Developmental Biology, University of Colorado Boulder, Boulder, CO 80309 USA
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25
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Josselyn SA, Tonegawa S. Memory engrams: Recalling the past and imagining the future. Science 2020; 367:367/6473/eaaw4325. [PMID: 31896692 DOI: 10.1126/science.aaw4325] [Citation(s) in RCA: 446] [Impact Index Per Article: 111.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
In 1904, Richard Semon introduced the term "engram" to describe the neural substrate for storing memories. An experience, Semon proposed, activates a subset of cells that undergo off-line, persistent chemical and/or physical changes to become an engram. Subsequent reactivation of this engram induces memory retrieval. Although Semon's contributions were largely ignored in his lifetime, new technologies that allow researchers to image and manipulate the brain at the level of individual neurons has reinvigorated engram research. We review recent progress in studying engrams, including an evaluation of evidence for the existence of engrams, the importance of intrinsic excitability and synaptic plasticity in engrams, and the lifetime of an engram. Together, these findings are beginning to define an engram as the basic unit of memory.
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Affiliation(s)
- Sheena A Josselyn
- Program in Neurosciences & Mental Health, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada. .,Department of Psychology, University of Toronto, Toronto, Ontario M5S 3G3, Canada.,Department of Physiology, University of Toronto, Toronto, Ontario M5G 1X8, Canada.,Institute of Medical Sciences, University of Toronto, Toronto, Ontario M5S 1A8, Canada.,Brain, Mind & Consciousness Program, Canadian Institute for Advanced Research (CIFAR), Toronto, Ontario M5G 1M1, Canada
| | - Susumu Tonegawa
- RIKEN-MIT Laboratory for Neural Circuit Genetics at the Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. .,Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Harel A, Ryan TJ. The memory toolbox: how genetic manipulations and cellular imaging are transforming our understanding of learned information. Curr Opin Behav Sci 2020. [DOI: 10.1016/j.cobeha.2020.02.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Frankland PW, Josselyn SA, Köhler S. The neurobiological foundation of memory retrieval. Nat Neurosci 2019; 22:1576-1585. [PMID: 31551594 DOI: 10.1038/s41593-019-0493-1] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 08/08/2019] [Indexed: 02/07/2023]
Abstract
Memory retrieval involves the interaction between external sensory or internally generated cues and stored memory traces (or engrams) in a process termed 'ecphory'. While ecphory has been examined in human cognitive neuroscience research, its neurobiological foundation is less understood. To the extent that ecphory involves 'reawakening' of engrams, leveraging recently developed technologies that can identify and manipulate engrams in rodents provides a fertile avenue for examining retrieval at the level of neuronal ensembles. Here we evaluate emerging neuroscientific research of this type, using cognitive theory as a guiding principle to organize and interpret initial findings. Our Review highlights the critical interaction between engrams and retrieval cues (environmental or artificial) for memory accessibility and retrieval success. These findings also highlight the intimate relationship between the mechanisms important in forming engrams and those important in their recovery, as captured in the cognitive notion of 'encoding specificity'. Finally, we identify several questions that currently remain unanswered.
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Affiliation(s)
- Paul W Frankland
- Program in Neurosciences & Mental Health, Hospital for Sick Children, Toronto, Ontario, Canada. .,Institute of Medical Sciences, University of Toronto, Toronto, Ontario, Canada. .,Department of Psychology, University of Toronto, Toronto, Ontario, Canada. .,Department of Physiology, University of Toronto, Toronto, Ontario, Canada. .,Child & Brain Development Program, Canadian Institute for Advanced Research, Toronto, Ontario, Canada.
| | - Sheena A Josselyn
- Program in Neurosciences & Mental Health, Hospital for Sick Children, Toronto, Ontario, Canada.,Institute of Medical Sciences, University of Toronto, Toronto, Ontario, Canada.,Department of Psychology, University of Toronto, Toronto, Ontario, Canada.,Department of Physiology, University of Toronto, Toronto, Ontario, Canada.,Brain, Mind & Consciousness Program, Canadian Institute for Advanced Research, Toronto, Ontario, Canada
| | - Stefan Köhler
- Department of Psychology, University of Western Ontario, London, Ontario, Canada. .,The Brain and Mind Institute, University of Western Ontario, London, Ontario, Canada.
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Neuronal competition: microcircuit mechanisms define the sparsity of the engram. Curr Opin Neurobiol 2018; 54:163-170. [PMID: 30423499 DOI: 10.1016/j.conb.2018.10.013] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 10/11/2018] [Accepted: 10/24/2018] [Indexed: 11/23/2022]
Abstract
Extensive work in computational modeling has highlighted the advantages for employing sparse yet distributed data representation and storage Kanerva (1998), properties that extend to neuronal networks encoding mnemonic information (memory traces or engrams). While neurons that participate in an engram are distributed across multiple brain regions, within each region, the cellular sparsity of the mnemonic representation appears to be quite fixed. Although technological advances have enabled significant progress in identifying and manipulating engrams, relatively little is known about the region-dependent microcircuit rules governing the cellular sparsity of an engram. Here we review recent studies examining the mechanisms that help shape engram architecture and examine how these processes may regulate memory function. We speculate that countervailing forces in local microcircuits contribute to the generation and maintenance of engrams and discuss emerging questions regarding how engrams are formed, stored and used.
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Outsmarting (and outrunning) nature's harsh decree. Nat Neurosci 2018; 21:1141-1142. [PMID: 30127426 DOI: 10.1038/s41593-018-0214-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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