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Masala N, Mittag M, Giovannetti EA, O'Neil DA, Distler FJ, Rupprecht P, Helmchen F, Yuste R, Fuhrmann M, Beck H, Wenzel M, Kelly T. Aberrant hippocampal Ca 2+ microwaves following synapsin-dependent adeno-associated viral expression of Ca 2+ indicators. eLife 2024; 13:RP93804. [PMID: 39042440 PMCID: PMC11265795 DOI: 10.7554/elife.93804] [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] [Indexed: 07/24/2024] Open
Abstract
Genetically encoded calcium indicators (GECIs) such as GCaMP are invaluable tools in neuroscience to monitor neuronal activity using optical imaging. The viral transduction of GECIs is commonly used to target expression to specific brain regions, can be conveniently used with any mouse strain of interest without the need for prior crossing with a GECI mouse line, and avoids potential hazards due to the chronic expression of GECIs during development. A key requirement for monitoring neuronal activity with an indicator is that the indicator itself minimally affects activity. Here, using common adeno-associated viral (AAV) transduction procedures, we describe spatially confined aberrant Ca2+ microwaves slowly travelling through the hippocampus following expression of GCaMP6, GCaMP7, or R-CaMP1.07 driven by the synapsin promoter with AAV-dependent gene transfer in a titre-dependent fashion. Ca2+ microwaves developed in hippocampal CA1 and CA3, but not dentate gyrus nor neocortex, were typically first observed at 4 wk after viral transduction, and persisted up to at least 8 wk. The phenomenon was robust and observed across laboratories with various experimenters and setups. Our results indicate that aberrant hippocampal Ca2+ microwaves depend on the promoter and viral titre of the GECI, density of expression, as well as the targeted brain region. We used an alternative viral transduction method of GCaMP which avoids this artefact. The results show that commonly used Ca2+-indicator AAV transduction procedures can produce artefactual Ca2+ responses. Our aim is to raise awareness in the field of these artefactual transduction-induced Ca2+ microwaves, and we provide a potential solution.
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Affiliation(s)
- Nicola Masala
- University of Bonn, Faculty of Medicine, Institute for Experimental Epileptology and Cognition Research (IEECR)BonnGermany
- University Hospital BonnBonnGermany
- Department of Epileptology, University Hospital BonnBonnGermany
| | - Manuel Mittag
- Neuroimmunology and Imaging Group, German Center for Neurodegenerative Diseases (DZNE)BonnGermany
| | | | - Darik A O'Neil
- NeuroTechnology Center, Columbia UniversityNew YorkUnited States
| | - Fabian J Distler
- University of Bonn, Faculty of Medicine, Institute for Experimental Epileptology and Cognition Research (IEECR)BonnGermany
- University Hospital BonnBonnGermany
| | - Peter Rupprecht
- Brain Research Institute, University of ZurichZurichSwitzerland
- Neuroscience Center Zurich, University of ZurichZurichSwitzerland
| | - Fritjof Helmchen
- Brain Research Institute, University of ZurichZurichSwitzerland
- Neuroscience Center Zurich, University of ZurichZurichSwitzerland
| | - Rafael Yuste
- NeuroTechnology Center, Columbia UniversityNew YorkUnited States
| | - Martin Fuhrmann
- Neuroimmunology and Imaging Group, German Center for Neurodegenerative Diseases (DZNE)BonnGermany
| | - Heinz Beck
- University of Bonn, Faculty of Medicine, Institute for Experimental Epileptology and Cognition Research (IEECR)BonnGermany
- University Hospital BonnBonnGermany
- German Center for Neurodegenerative Diseases (DZNE)BonnGermany
| | - Michael Wenzel
- University of Bonn, Faculty of Medicine, Institute for Experimental Epileptology and Cognition Research (IEECR)BonnGermany
- University Hospital BonnBonnGermany
- Department of Epileptology, University Hospital BonnBonnGermany
| | - Tony Kelly
- University of Bonn, Faculty of Medicine, Institute for Experimental Epileptology and Cognition Research (IEECR)BonnGermany
- University Hospital BonnBonnGermany
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2
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Wirt RA, Soluoku TK, Ricci RM, Seamans JK, Hyman JM. Temporal information in the anterior cingulate cortex relates to accumulated experiences. Curr Biol 2024; 34:2921-2931.e3. [PMID: 38908372 DOI: 10.1016/j.cub.2024.05.045] [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: 09/08/2023] [Revised: 04/02/2024] [Accepted: 05/23/2024] [Indexed: 06/24/2024]
Abstract
Anterior cingulate cortex (ACC) activity is important for operations that require the ability to integrate multiple experiences over time, such as rule learning, cognitive flexibility, working memory, and long-term memory recall. To shed light on this, we analyzed neuronal activity while rats repeated the same behaviors during hour-long sessions to investigate how activity changed over time. We recorded neuronal ensembles as rats performed a decision-free operant task with varying reward likelihoods at three different response ports (n = 5). Neuronal state space analysis revealed that each repetition of a behavior was distinct, with more recent behaviors more similar than those further apart in time. ACC activity was dominated by a slow, gradual change in low-dimensional representations of neural state space aligning with the pace of behavior. Temporal progression, or drift, was apparent on the top principal component for every session and was driven by the accumulation of experiences and not an internal clock. Notably, these signals were consistent across subjects, allowing us to accurately predict trial numbers based on a model trained on data from a different animal. We observed that non-continuous ramping firing rates over extended durations (tens of minutes) drove the low-dimensional ensemble representations. 40% of ACC neurons' firing ramped over a range of trial lengths and combinations of shorter duration ramping neurons created ensembles that tracked longer durations. These findings provide valuable insights into how the ACC, at an ensemble level, conveys temporal information by reflecting the accumulation of experiences over extended periods.
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Affiliation(s)
- Ryan A Wirt
- University of Nevada, Las Vegas, Interdisciplinary Program in Neuroscience, Las Vegas, NV 89154-1003, USA
| | - Talha K Soluoku
- University of Nevada, Las Vegas, Interdisciplinary Program in Neuroscience, Las Vegas, NV 89154-1003, USA
| | - Ryan M Ricci
- University of Nevada, Las Vegas, College of Medical Sciences, Las Vegas, NV 89154-1003, USA
| | - Jeremy K Seamans
- University of British Columbia, Department of Psychiatry, 2255 Wesbrook Mall, Vancouver, BC V6T 2A1, Canada
| | - James M Hyman
- University of Nevada, Las Vegas, Interdisciplinary Program in Neuroscience, Las Vegas, NV 89154-1003, USA; University of Nevada, Las Vegas, Department of Psychology, Las Vegas, NV 89154-1003, USA.
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3
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McNaughton N, Bannerman D. The homogenous hippocampus: How hippocampal cells process available and potential goals. Prog Neurobiol 2024; 240:102653. [PMID: 38960002 DOI: 10.1016/j.pneurobio.2024.102653] [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: 01/04/2024] [Revised: 04/25/2024] [Accepted: 06/24/2024] [Indexed: 07/05/2024]
Abstract
We present here a view of the firing patterns of hippocampal cells that is contrary, both functionally and anatomically, to conventional wisdom. We argue that the hippocampus responds to efference copies of goals encoded elsewhere; and that it uses these to detect and resolve conflict or interference between goals in general. While goals can involve space, hippocampal cells do not encode spatial (or other special types of) memory, as such. We also argue that the transverse circuits of the hippocampus operate in an essentially homogeneous way along its length. The apparently different functions of different parts (e.g. memory retrieval versus anxiety) result from the different (situational/motivational) inputs on which those parts perform the same fundamental computational operations. On this view, the key role of the hippocampus is the iterative adjustment, via Papez-like circuits, of synaptic weights in cell assemblies elsewhere.
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Affiliation(s)
- Neil McNaughton
- Department of Psychology and Brain Health Research Centre, University of Otago, POB56, Dunedin 9054, New Zealand.
| | - David Bannerman
- Department of Experimental Psychology, University of Oxford, South Parks Road, Oxford, England, UK
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4
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Zuniga A, Han J, Miller-Crews I, Agee LA, Hofmann HA, Drew MR. Extinction training suppresses activity of fear memory ensembles across the hippocampus and alters transcriptomes of fear-encoding cells. Neuropsychopharmacology 2024:10.1038/s41386-024-01897-0. [PMID: 38877180 DOI: 10.1038/s41386-024-01897-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 05/06/2024] [Accepted: 05/30/2024] [Indexed: 06/16/2024]
Abstract
Contextual fear conditioning has been shown to activate a set of "fear ensemble" cells in the hippocampal dentate gyrus (DG) whose reactivation is necessary and sufficient for expression of contextual fear. We previously demonstrated that extinction learning suppresses reactivation of these fear ensemble cells and activates a competing set of DG cells-the "extinction ensemble." Here, we tested whether extinction was sufficient to suppress reactivation in other regions and used single nucleus RNA sequencing (snRNA-seq) of cells in the dorsal dentate gyrus to examine how extinction affects the transcriptomic activity of fear ensemble and fear recall-activated cells. Our results confirm the suppressive effects of extinction in the dorsal and ventral dentate gyrus and demonstrate that this same effect extends to fear ensemble cells located in the dorsal CA1. Interestingly, the extinction-induced suppression of fear ensemble activity was not detected in ventral CA1. Our snRNA-seq analysis demonstrates that extinction training markedly changes transcription patterns in fear ensemble cells and that cells activated during recall of fear and recall of extinction have distinct transcriptomic profiles. Together, our results indicate that extinction training suppresses a broad portion of the fear ensemble in the hippocampus, and this suppression is accompanied by changes in the transcriptomes of fear ensemble cells and the emergence of a transcriptionally unique extinction ensemble.
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Affiliation(s)
- Alfredo Zuniga
- Department of Neuroscience, The University of Texas at Austin, Austin, TX, USA
- Center for Learning and Memory, University of Texas at Austin, Austin, TX, USA
- Department of Neuroscience, The College of Wooster, 1189 Beall Ave, Wooster, OH, 44691, USA
| | - Jiawei Han
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX, USA
- Interdisciplinary Life Sciences Graduate Programs, The University of Texas at Austin, Austin, TX, USA
| | - Isaac Miller-Crews
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX, USA
| | - Laura A Agee
- Department of Neuroscience, The University of Texas at Austin, Austin, TX, USA
- Center for Learning and Memory, University of Texas at Austin, Austin, TX, USA
| | - Hans A Hofmann
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX, USA.
- Interdisciplinary Life Sciences Graduate Programs, The University of Texas at Austin, Austin, TX, USA.
- Institute for Neuroscience, The University of Texas at Austin, Austin, TX, USA.
| | - Michael R Drew
- Department of Neuroscience, The University of Texas at Austin, Austin, TX, USA.
- Center for Learning and Memory, University of Texas at Austin, Austin, TX, USA.
- Institute for Neuroscience, The University of Texas at Austin, Austin, TX, USA.
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5
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Fenton AA. Remapping revisited: how the hippocampus represents different spaces. Nat Rev Neurosci 2024; 25:428-448. [PMID: 38714834 DOI: 10.1038/s41583-024-00817-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/04/2024] [Indexed: 05/25/2024]
Abstract
The representation of distinct spaces by hippocampal place cells has been linked to changes in their place fields (the locations in the environment where the place cells discharge strongly), a phenomenon that has been termed 'remapping'. Remapping has been assumed to be accompanied by the reorganization of subsecond cofiring relationships among the place cells, potentially maximizing hippocampal information coding capacity. However, several observations challenge this standard view. For example, place cells exhibit mixed selectivity, encode non-positional variables, can have multiple place fields and exhibit unreliable discharge in fixed environments. Furthermore, recent evidence suggests that, when measured at subsecond timescales, the moment-to-moment cofiring of a pair of cells in one environment is remarkably similar in another environment, despite remapping. Here, I propose that remapping is a misnomer for the changes in place fields across environments and suggest instead that internally organized manifold representations of hippocampal activity are actively registered to different environments to enable navigation, promote memory and organize knowledge.
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Affiliation(s)
- André A Fenton
- Center for Neural Science, New York University, New York, NY, USA.
- Neuroscience Institute at the NYU Langone Medical Center, New York, NY, USA.
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6
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Lopez MR, Wasberg SMH, Gagliardi CM, Normandin ME, Muzzio IA. Mystery of the memory engram: History, current knowledge, and unanswered questions. Neurosci Biobehav Rev 2024; 159:105574. [PMID: 38331127 DOI: 10.1016/j.neubiorev.2024.105574] [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: 09/18/2023] [Revised: 12/22/2023] [Accepted: 02/03/2024] [Indexed: 02/10/2024]
Abstract
The quest to understand the memory engram has intrigued humans for centuries. Recent technological advances, including genetic labelling, imaging, optogenetic and chemogenetic techniques, have propelled the field of memory research forward. These tools have enabled researchers to create and erase memory components. While these innovative techniques have yielded invaluable insights, they often focus on specific elements of the memory trace. Genetic labelling may rely on a particular immediate early gene as a marker of activity, optogenetics may activate or inhibit one specific type of neuron, and imaging may capture activity snapshots in a given brain region at specific times. Yet, memories are multifaceted, involving diverse arrays of neuronal subpopulations, circuits, and regions that work in concert to create, store, and retrieve information. Consideration of contributions of both excitatory and inhibitory neurons, micro and macro circuits across brain regions, the dynamic nature of active ensembles, and representational drift is crucial for a comprehensive understanding of the complex nature of memory.
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Affiliation(s)
- M R Lopez
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine and Science, Rochester, MN, United States
| | - S M H Wasberg
- Department of Psychological and Brain Sciences, University of Iowa, Iowa City, IA 52242, USA
| | - C M Gagliardi
- Department of Psychological and Brain Sciences, University of Iowa, Iowa City, IA 52242, USA
| | - M E Normandin
- Department of Psychological and Brain Sciences, University of Iowa, Iowa City, IA 52242, USA
| | - I A Muzzio
- Department of Psychological and Brain Sciences, University of Iowa, Iowa City, IA 52242, USA.
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7
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Shi J, Nutkovich B, Kushinsky D, Rao BY, Herrlinger SA, Mihaila TS, Malina KCK, O’Toole CK, Conde Paredes ME, Yong HC, Varol E, Losonczy A, Spiegel I. 2P-NucTag: on-demand phototagging for molecular analysis of functionally identified cortical neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.21.586118. [PMID: 38585980 PMCID: PMC10996538 DOI: 10.1101/2024.03.21.586118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Neural circuits are characterized by genetically and functionally diverse cell types. A mechanistic understanding of circuit function is predicated on linking the genetic and physiological properties of individual neurons. However, it remains highly challenging to map the functional properties of transcriptionally heterogeneous neuronal subtypes in mammalian cortical circuits in vivo. Here, we introduce a high-throughput two-photon nuclear phototagging (2P-NucTag) approach optimized for on-demand and indelible labeling of single neurons via a photoactivatable red fluorescent protein following in vivo functional characterization in behaving mice. We demonstrate the utility of this function-forward pipeline by selectively labeling and transcriptionally profiling previously inaccessible 'place' and 'silent' cells in the mouse hippocampus. Our results reveal unexpected differences in gene expression between these hippocampal pyramidal neurons with distinct spatial coding properties. Thus, 2P-NucTag opens a new way to uncover the molecular principles that govern the functional organization of neural circuits.
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Affiliation(s)
- Jingcheng Shi
- Department of Neuroscience, Columbia University, New York, NY, United States
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, United States
- Doctoral Program in Neurobiology and Behavior, Columbia University, New York, NY, United States
| | - Boaz Nutkovich
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel
- Department of Molecular Neuroscience, Weizmann Institute of Science, Rehovot, Israel
| | - Dahlia Kushinsky
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel
- Department of Molecular Neuroscience, Weizmann Institute of Science, Rehovot, Israel
| | - Bovey Y. Rao
- Department of Neuroscience, Columbia University, New York, NY, United States
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, United States
- Doctoral Program in Neurobiology and Behavior, Columbia University, New York, NY, United States
| | - Stephanie A. Herrlinger
- Department of Neuroscience, Columbia University, New York, NY, United States
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, United States
| | - Tiberiu S. Mihaila
- Department of Neuroscience, Columbia University, New York, NY, United States
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, United States
| | - Katayun Cohen-Kashi Malina
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel
- Department of Molecular Neuroscience, Weizmann Institute of Science, Rehovot, Israel
| | - Cliodhna K. O’Toole
- Department of Neuroscience, Columbia University, New York, NY, United States
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, United States
| | - Margaret E. Conde Paredes
- Department of Neuroscience, Columbia University, New York, NY, United States
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, United States
- Doctoral Program in Neurobiology and Behavior, Columbia University, New York, NY, United States
- Tandon School of Engineering, New York University, New York, NY, United States
| | - Hyun Choong Yong
- Department of Neuroscience, Columbia University, New York, NY, United States
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, United States
| | - Erdem Varol
- Tandon School of Engineering, New York University, New York, NY, United States
| | - Attila Losonczy
- Department of Neuroscience, Columbia University, New York, NY, United States
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, United States
| | - Ivo Spiegel
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel
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8
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Sosa M, Plitt MH, Giocomo LM. Hippocampal sequences span experience relative to rewards. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.12.27.573490. [PMID: 38234842 PMCID: PMC10793396 DOI: 10.1101/2023.12.27.573490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2024]
Abstract
Hippocampal place cells fire in sequences that span spatial environments and non-spatial modalities, suggesting that hippocampal activity can anchor to the most behaviorally salient aspects of experience. As reward is a highly salient event, we hypothesized that sequences of hippocampal activity can anchor to rewards. To test this, we performed two-photon imaging of hippocampal CA1 neurons as mice navigated virtual environments with changing hidden reward locations. When the reward moved, the firing fields of a subpopulation of cells moved to the same relative position with respect to reward, constructing a sequence of reward-relative cells that spanned the entire task structure. The density of these reward-relative sequences increased with task experience as additional neurons were recruited to the reward-relative population. Conversely, a largely separate subpopulation maintained a spatially-based place code. These findings thus reveal separate hippocampal ensembles can flexibly encode multiple behaviorally salient reference frames, reflecting the structure of the experience.
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Affiliation(s)
- Marielena Sosa
- Department of Neurobiology, Stanford University School of Medicine; Stanford, CA, USA
| | - Mark H. Plitt
- Department of Neurobiology, Stanford University School of Medicine; Stanford, CA, USA
- Present address: Department of Molecular and Cell Biology, University of California Berkeley; Berkeley, CA, USA
| | - Lisa M. Giocomo
- Department of Neurobiology, Stanford University School of Medicine; Stanford, CA, USA
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9
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Krishnan S, Sheffield ME. Reward Expectation Reduces Representational Drift in the Hippocampus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.21.572809. [PMID: 38187677 PMCID: PMC10769341 DOI: 10.1101/2023.12.21.572809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
Spatial memory in the hippocampus involves dynamic neural patterns that change over days, termed representational drift. While drift may aid memory updating, excessive drift could impede retrieval. Memory retrieval is influenced by reward expectation during encoding, so we hypothesized that diminished reward expectation would exacerbate representational drift. We found that high reward expectation limited drift, with CA1 representations on one day gradually re-emerging over successive trials the following day. Conversely, the absence of reward expectation resulted in increased drift, as the gradual re-emergence of the previous day's representation did not occur. At the single cell level, lowering reward expectation caused an immediate increase in the proportion of place-fields with low trial-to-trial reliability. These place fields were less likely to be reinstated the following day, underlying increased drift in this condition. In conclusion, heightened reward expectation improves memory encoding and retrieval by maintaining reliable place fields that are gradually reinstated across days, thereby minimizing representational drift.
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10
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Tuncdemir SN, Grosmark AD, Chung H, Luna VM, Lacefield CO, Losonczy A, Hen R. Adult-born granule cells facilitate remapping of spatial and non-spatial representations in the dentate gyrus. Neuron 2023; 111:4024-4039.e7. [PMID: 37820723 PMCID: PMC10841867 DOI: 10.1016/j.neuron.2023.09.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 06/10/2023] [Accepted: 09/13/2023] [Indexed: 10/13/2023]
Abstract
Adult-born granule cells (abGCs) have been implicated in memory discrimination through a neural computation known as pattern separation. Here, using in vivo Ca2+ imaging, we examined how chronic ablation or acute chemogenetic silencing of abGCs affects the activity of mature granule cells (mGCs). In both cases, we observed altered remapping of mGCs. Rather than broadly modulating the activity of all mGCs, abGCs promote the remapping of place cells' firing fields while increasing rate remapping of mGCs that represent sensory cues. In turn, these remapping deficits are associated with behavioral impairments in animals' ability to correctly identify new goal locations. Thus, abGCs facilitate pattern separation through the formation of non-overlapping representations for identical sensory cues encountered in different locations. In the absence of abGCs, the dentate gyrus shifts to a state that is dominated by cue information, a situation that is consistent with the overgeneralization often observed in anxiety or age-related disorders.
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Affiliation(s)
- Sebnem N Tuncdemir
- Departments of Psychiatry and Neuroscience, Columbia University, New York, NY 10032, USA; Division of Systems Neuroscience, New York State Psychiatric Institute, New York, NY 10032, USA
| | - Andres D Grosmark
- Department of Neuroscience, Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Hannah Chung
- Division of Systems Neuroscience, New York State Psychiatric Institute, New York, NY 10032, USA
| | - Victor M Luna
- Departments of Psychiatry and Neuroscience, Columbia University, New York, NY 10032, USA; Division of Systems Neuroscience, New York State Psychiatric Institute, New York, NY 10032, USA
| | - Clay O Lacefield
- Departments of Psychiatry and Neuroscience, Columbia University, New York, NY 10032, USA; Division of Systems Neuroscience, New York State Psychiatric Institute, New York, NY 10032, USA
| | - Attila Losonczy
- Department of Neuroscience, Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Rene Hen
- Departments of Psychiatry and Neuroscience, Columbia University, New York, NY 10032, USA; Division of Systems Neuroscience, New York State Psychiatric Institute, New York, NY 10032, USA.
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11
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Chiu Y, Dong C, Krishnan S, Sheffield MEJ. The Precision of Place Fields Governs Their Fate across Epochs of Experience. eNeuro 2023; 10:ENEURO.0261-23.2023. [PMID: 37973379 PMCID: PMC10706252 DOI: 10.1523/eneuro.0261-23.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 10/30/2023] [Accepted: 10/31/2023] [Indexed: 11/19/2023] Open
Abstract
Spatial memories are represented by hippocampal place cells during navigation. This spatial code is dynamic, undergoing changes across time, known as representational drift, and across changes in internal state, even while navigating the same spatial environment with consistent behavior. A dynamic code may provide the hippocampus a means to track distinct epochs of experience that occur at different times or during different internal states and update spatial memories. Changes to the spatial code include place fields (PFs) that remap to new locations and place fields that vanish, while others are stable. However, what determines place field fate across epochs remains unclear. We measured the lap-by-lap properties of place cells in mice during navigation for a block of trials in a rewarded virtual environment. We then determined the position of the place fields in another block of trials in the same spatial environment either separated by a day (a distinct temporal epoch) or during the same session but with reward removed to change reward expectation (a distinct internal state epoch). We found that place cells with remapped place fields across epochs tended to have lower spatial precision during navigation in the initial epoch. Place cells with stable or vanished place fields tended to have higher spatial precision. We conclude that place cells with less precise place fields have greater spatial flexibility, allowing them to respond to, and track, distinct epochs of experience in the same spatial environment, while place cells with precise place fields generally preserve spatial information when their fields reappear.
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Affiliation(s)
- YuHung Chiu
- Department of Physics, University of Chicago, Chicago, 60637, IL
- Institute for Neuroscience, University of Chicago, Chicago, 60637, IL
| | - Can Dong
- Department of Neurobiology, University of Chicago, Chicago, 60637, IL
- Institute for Neuroscience, University of Chicago, Chicago, 60637, IL
| | - Seetha Krishnan
- Department of Neurobiology, University of Chicago, Chicago, 60637, IL
- Institute for Neuroscience, University of Chicago, Chicago, 60637, IL
| | - Mark E J Sheffield
- Department of Neurobiology, University of Chicago, Chicago, 60637, IL
- Institute for Neuroscience, University of Chicago, Chicago, 60637, IL
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12
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Plitt MH, Kaganovsky K, Südhof TC, Giocomo LM. Hippocampal place code plasticity in CA1 requires postsynaptic membrane fusion. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.20.567978. [PMID: 38045362 PMCID: PMC10690209 DOI: 10.1101/2023.11.20.567978] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
Rapid delivery of glutamate receptors to the postsynaptic membrane via vesicle fusion is a central component of synaptic plasticity. However, it is unknown how this process supports specific neural computations during behavior. To bridge this gap, we combined conditional genetic deletion of a component of the postsynaptic membrane fusion machinery, Syntaxin3 (Stx3), in hippocampal CA1 neurons of mice with population in vivo calcium imaging. This approach revealed that Stx3 is necessary for forming the neural dynamics that support novelty processing, spatial reward memory and offline memory consolidation. In contrast, CA1 Stx3 was dispensable for maintaining aspects of the neural code that exist presynaptic to CA1 such as representations of context and space. Thus, manipulating postsynaptic membrane fusion identified computations that specifically require synaptic restructuring via membrane trafficking in CA1 and distinguished them from neural representation that could be inherited from upstream brain regions or learned through other mechanisms.
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13
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Dyakonova VE. DNA Instability in Neurons: Lifespan Clock and Driver of Evolution. BIOCHEMISTRY. BIOKHIMIIA 2023; 88:1719-1731. [PMID: 38105193 DOI: 10.1134/s0006297923110044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 07/19/2023] [Accepted: 09/20/2023] [Indexed: 12/19/2023]
Abstract
In the last ten years, the discovery of neuronal DNA postmitotic instability has changed the theoretical landscape in neuroscience and, more broadly, biology. In 2003, A. M. Olovnikov suggested that neuronal DNA is the "initial substrate of aging". Recent experimental data have significantly increased the likelihood of this hypothesis. How does neuronal DNA accumulate damage and in what genome regions? What factors contribute to this process and how are they associated with aging and lifespan? These questions will be discussed in the review. In the course of Metazoan evolution, the instability of neuronal DNA has been accompanied by searching for the pathways to reduce the biological cost of brain activity. Various processes and activities, such as sleep, evolutionary increase in the number of neurons in the vertebrate brain, adult neurogenesis, distribution of neuronal activity, somatic polyploidy, and RNA editing in cephalopods, can be reconsidered in the light of the trade-off between neuronal plasticity and DNA instability in neurons. This topic is of considerable importance for both fundamental neuroscience and translational medicine.
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Affiliation(s)
- Varvara E Dyakonova
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, Moscow, 119334, Russia.
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14
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Levy ERJ, Carrillo-Segura S, Park EH, Redman WT, Hurtado JR, Chung S, Fenton AA. A manifold neural population code for space in hippocampal coactivity dynamics independent of place fields. Cell Rep 2023; 42:113142. [PMID: 37742193 PMCID: PMC10842170 DOI: 10.1016/j.celrep.2023.113142] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 06/14/2023] [Accepted: 08/30/2023] [Indexed: 09/26/2023] Open
Abstract
Hippocampus place cell discharge is temporally unreliable across seconds and days, and place fields are multimodal, suggesting an "ensemble cofiring" spatial coding hypothesis with manifold dynamics that does not require reliable spatial tuning, in contrast to hypotheses based on place field (spatial tuning) stability. We imaged mouse CA1 (cornu ammonis 1) ensembles in two environments across three weeks to evaluate these coding hypotheses. While place fields "remap," being more distinct between than within environments, coactivity relationships generally change less. Decoding location and environment from 1-s ensemble location-specific activity is effective and improves with experience. Decoding environment from cell-pair coactivity relationships is also effective and improves with experience, even after removing place tuning. Discriminating environments from 1-s ensemble coactivity relies crucially on the cells with the most anti-coactive cell-pair relationships because activity is internally organized on a low-dimensional manifold of non-linear coactivity relationships that intermittently reregisters to environments according to the anti-cofiring subpopulation activity.
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Affiliation(s)
| | - Simón Carrillo-Segura
- Center for Neural Science, New York University, New York, NY 10003, USA; Graduate Program in Mechanical and Aerospace Engineering, Tandon School of Engineering, New York University, Brooklyn, NY 11201, USA
| | - Eun Hye Park
- Center for Neural Science, New York University, New York, NY 10003, USA
| | - William Thomas Redman
- Interdepartmental Graduate Program in Dynamical Neuroscience, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | | | - SueYeon Chung
- Center for Neural Science, New York University, New York, NY 10003, USA; Flatiron Institute Center for Computational Neuroscience, New York, NY 10010, USA
| | - André Antonio Fenton
- Center for Neural Science, New York University, New York, NY 10003, USA; Neuroscience Institute at the NYU Langone Medical Center, New York, NY 10016, USA.
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15
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Lee JQ, Brandon MP. Time and experience are independent determinants of representational drift in CA1. Neuron 2023; 111:2275-2277. [PMID: 37536286 DOI: 10.1016/j.neuron.2023.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 07/03/2023] [Accepted: 07/04/2023] [Indexed: 08/05/2023]
Abstract
In this issue of Neuron, Khatib et al.1 and Geva et al.2 present complementary and breakthrough discoveries demonstrating that elapsed time and active experience independently affect unique aspects of representational drift in the hippocampus.
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Affiliation(s)
- J Quinn Lee
- Department of Psychiatry, Faculty of Medicine, Douglas Hospital Research Centre, McGill University, Montreal, Canada
| | - Mark P Brandon
- Department of Psychiatry, Faculty of Medicine, Douglas Hospital Research Centre, McGill University, Montreal, Canada; Integrated Program in Neuroscience, Faculty of Medicine, McGill University, Montreal, Canada.
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16
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Ambrogioni L, Ólafsdóttir HF. Rethinking the hippocampal cognitive map as a meta-learning computational module. Trends Cogn Sci 2023:S1364-6613(23)00128-6. [PMID: 37357064 DOI: 10.1016/j.tics.2023.05.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 04/26/2023] [Accepted: 05/24/2023] [Indexed: 06/27/2023]
Abstract
A hallmark of biological intelligence is the ability to adaptively draw on past experience to guide behaviour under novel situations. Yet, the neurobiological principles that underlie this form of meta-learning remain relatively unexplored. In this Opinion, we review the existing literature on hippocampal spatial representations and reinforcement learning theory and describe a novel theoretical framework that aims to account for biological meta-learning. We conjecture that so-called hippocampal cognitive maps of familiar environments are part of a larger meta-representation (meta-map) that encodes information states and sources, which support exploration and provides a foundation for learning. We also introduce concrete hypotheses on how these generic states can be encoded using a principle of superposition.
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Affiliation(s)
- Luca Ambrogioni
- Donders Institute for Brain, Cognition & Behaviour, Radboud Universiteit, Nijmegen, The Netherlands.
| | - H Freyja Ólafsdóttir
- Donders Institute for Brain, Cognition & Behaviour, Radboud Universiteit, Nijmegen, The Netherlands.
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17
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Geva N, Deitch D, Rubin A, Ziv Y. Time and experience differentially affect distinct aspects of hippocampal representational drift. Neuron 2023:S0896-6273(23)00378-1. [PMID: 37315556 DOI: 10.1016/j.neuron.2023.05.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 02/22/2023] [Accepted: 05/08/2023] [Indexed: 06/16/2023]
Abstract
Hippocampal activity is critical for spatial memory. Within a fixed, familiar environment, hippocampal codes gradually change over timescales of days to weeks-a phenomenon known as representational drift. The passage of time and the amount of experience are two factors that profoundly affect memory. However, thus far, it has remained unclear to what extent these factors drive hippocampal representational drift. Here, we longitudinally recorded large populations of hippocampal neurons in mice while they repeatedly explored two different familiar environments that they visited at different time intervals over weeks. We found that time and experience differentially affected distinct aspects of representational drift: the passage of time drove changes in neuronal activity rates, whereas experience drove changes in the cells' spatial tuning. Changes in spatial tuning were context specific and largely independent of changes in activity rates. Thus, our results suggest that representational drift is a multi-faceted process governed by distinct neuronal mechanisms.
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Affiliation(s)
- Nitzan Geva
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Daniel Deitch
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Alon Rubin
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel.
| | - Yaniv Ziv
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel.
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18
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Khatib D, Ratzon A, Sellevoll M, Barak O, Morris G, Derdikman D. Active experience, not time, determines within-day representational drift in dorsal CA1. Neuron 2023:S0896-6273(23)00387-2. [PMID: 37315557 DOI: 10.1016/j.neuron.2023.05.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 02/22/2023] [Accepted: 05/09/2023] [Indexed: 06/16/2023]
Abstract
Memories of past events can be recalled long after the event, indicating stability. But new experiences are also integrated into existing memories, indicating plasticity. In the hippocampus, spatial representations are known to remain stable but have also been shown to drift over long periods of time. We hypothesized that experience, more than the passage of time, is the driving force behind representational drift. We compared the within-day stability of place cells' representations in dorsal CA1 of the hippocampus of mice traversing two similar, familiar tracks for different durations. We found that the more time the animals spent actively traversing the environment, the greater the representational drift, regardless of the total elapsed time between visits. Our results suggest that spatial representation is a dynamic process, related to the ongoing experiences within a specific context, and is related to memory update rather than to passive forgetting.
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Affiliation(s)
- Dorgham Khatib
- Department of Neuroscience, The Rappaport Faculty of Medicine and Research Institute, Technion - Israel Institute of Technology, Haifa 32000, Israel
| | - Aviv Ratzon
- Department of Neuroscience, The Rappaport Faculty of Medicine and Research Institute, Technion - Israel Institute of Technology, Haifa 32000, Israel
| | - Mariell Sellevoll
- Department of Neuroscience, The Rappaport Faculty of Medicine and Research Institute, Technion - Israel Institute of Technology, Haifa 32000, Israel
| | - Omri Barak
- Department of Neuroscience, The Rappaport Faculty of Medicine and Research Institute, Technion - Israel Institute of Technology, Haifa 32000, Israel; Network Biology Research Laboratories, Technion - Israel Institute of Technology, Haifa 32000, Israel
| | - Genela Morris
- Department of Neuroscience, The Rappaport Faculty of Medicine and Research Institute, Technion - Israel Institute of Technology, Haifa 32000, Israel; Tel Aviv Sourasky Medical Center, Tel Aviv, Israel.
| | - Dori Derdikman
- Department of Neuroscience, The Rappaport Faculty of Medicine and Research Institute, Technion - Israel Institute of Technology, Haifa 32000, Israel.
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19
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de Snoo ML, Miller AMP, Ramsaran AI, Josselyn SA, Frankland PW. Exercise accelerates place cell representational drift. Curr Biol 2023; 33:R96-R97. [PMID: 36750030 PMCID: PMC9930168 DOI: 10.1016/j.cub.2022.12.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Stable neural ensembles are often thought to underlie stable learned behaviors and memory. Recent longitudinal experiments, however, that tracked the activity of the same neurons over days to weeks have shown that neuronal activity patterns can change over extended timescales even if behaviors remain the same - a phenomenon termed representational drift1. We have tested whether neural circuit remodeling, defined as any change in structural connectivity, contributes to representational drift. To do this, we tracked how hippocampal CA1 spatial representations of a familiar environment change with time in conventionally housed mice relative to mice housed with a running wheel. Voluntary exercise is an environmental stimulus that promotes hippocampal circuit remodeling, primarily via promoting adult neurogenesis in the dentate gyrus. Adult neurogenesis alters structural connectivity patterns, as the integration of adult-generated granule cells (abGCs) is a competitive process where new input-output synaptic connections may co-exist and/or even replace existing synaptic connections2. Comparing the spatial activity of downstream hippocampal CA1 place cells in the same familiar environment over two weeks, we found that the activity of place cells in exercise mice exhibited accelerated representational drift compared to control mice, suggesting that hippocampal circuit remodeling may indeed drive representational drift.
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Affiliation(s)
- Mitchell L de Snoo
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, 686 Bay Street, Toronto, Ontario, Canada, M5G 0A4; Institute of Medical Sciences, University of Toronto, 1 King's College Circle, Medical Sciences Building, Room 2374, Toronto, Ontario, Canada, M5S 1A8
| | - Adam M P Miller
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, 686 Bay Street, Toronto, Ontario, Canada, M5G 0A4
| | - Adam I Ramsaran
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, 686 Bay Street, Toronto, Ontario, Canada, M5G 0A4; Department of Psychology, University of Toronto, 100 St. George Street, 4th Floor Sidney Smith Hall, Toronto, Ontario, Canada, M5S 3G3
| | - Sheena A Josselyn
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, 686 Bay Street, Toronto, Ontario, Canada, M5G 0A4; Institute of Medical Sciences, University of Toronto, 1 King's College Circle, Medical Sciences Building, Room 2374, Toronto, Ontario, Canada, M5S 1A8; Department of Psychology, University of Toronto, 100 St. George Street, 4th Floor Sidney Smith Hall, Toronto, Ontario, Canada, M5S 3G3; Department of Physiology, University of Toronto, 1 King's College Circle, Medical Sciences Building, Toronto, Ontario, Canada, M5S 1A8; Child & Brain Development Program, Canadian Institute for Advanced Research, 661 University Avenue, Toronto, Ontario, Canada, M5G 1M1
| | - Paul W Frankland
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, 686 Bay Street, Toronto, Ontario, Canada, M5G 0A4; Institute of Medical Sciences, University of Toronto, 1 King's College Circle, Medical Sciences Building, Room 2374, Toronto, Ontario, Canada, M5S 1A8; Department of Psychology, University of Toronto, 100 St. George Street, 4th Floor Sidney Smith Hall, Toronto, Ontario, Canada, M5S 3G3; Department of Physiology, University of Toronto, 1 King's College Circle, Medical Sciences Building, Toronto, Ontario, Canada, M5S 1A8; Child & Brain Development Program, Canadian Institute for Advanced Research, 661 University Avenue, Toronto, Ontario, Canada, M5G 1M1.
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20
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Aery Jones EA, Giocomo LM. Neural ensembles in navigation: From single cells to population codes. Curr Opin Neurobiol 2023; 78:102665. [PMID: 36542882 PMCID: PMC9845194 DOI: 10.1016/j.conb.2022.102665] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 10/27/2022] [Accepted: 11/21/2022] [Indexed: 12/23/2022]
Abstract
The brain can represent behaviorally relevant information through the firing of individual neurons as well as the coordinated firing of ensembles of neurons. Neurons in the hippocampus and associated cortical regions participate in a variety of types of ensembles to support navigation. These ensemble types include single cell codes, population codes, time-compressed sequences, behavioral sequences, and engrams. We present the physiological basis and behavioral relevance of ensemble firing. We discuss how these traditional definitions of ensembles can constrain or expand potential analyses due to the underlying assumptions and abstractions made. We highlight how coding can change at the ensemble level while underlying single cell codes remain intact. Finally, we present how ensemble definitions could be broadened to better understand the full complexity of the brain.
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Affiliation(s)
- Emily A Aery Jones
- Department of Neurobiology, Stanford University School of Medicine, Stanford, CA, 94305, USA.
| | - Lisa M Giocomo
- Department of Neurobiology, Stanford University School of Medicine, Stanford, CA, 94305, USA.
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21
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Fukai T. Computational models of Idling brain activity for memory processing. Neurosci Res 2022; 189:75-82. [PMID: 36592825 DOI: 10.1016/j.neures.2022.12.024] [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: 12/28/2022] [Accepted: 12/29/2022] [Indexed: 01/01/2023]
Abstract
Studying the underlying neural mechanisms of cognitive functions of the brain is one of the central questions in modern biology. Moreover, it has significantly impacted the development of novel technologies in artificial intelligence. Spontaneous activity is a unique feature of the brain and is currently lacking in many artificially constructed intelligent machines. Spontaneous activity may represent the brain's idling states, which are internally driven by neuronal networks and possibly participate in offline processing during awake, sleep, and resting states. Evidence is accumulating that the brain's spontaneous activity is not mere noise but part of the mechanisms to process information about previous experiences. A bunch of literature has shown how previous sensory and behavioral experiences influence the subsequent patterns of brain activity with various methods in various animals. It seems, however, that the patterns of neural activity and their computational roles differ significantly from area to area and from function to function. In this article, I review the various forms of the brain's spontaneous activity, especially those observed during memory processing, and some attempts to model the generation mechanisms and computational roles of such activities.
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Affiliation(s)
- Tomoki Fukai
- Okinawa Institute of Science and Technology, Tancha 1919-1, Onna-son, Okinawa 904-0495, Japan.
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22
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Song C, Wei W, Wang T, Zhou M, Li Y, Xiao B, Huang D, Gu J, Shi L, Peng J, Jin D. Microglial infiltration mediates cognitive dysfunction in rat models of hypothalamic obesity via a hypothalamic-hippocampal circuit involving the lateral hypothalamic area. Front Cell Neurosci 2022; 16:971100. [PMID: 36072565 PMCID: PMC9443213 DOI: 10.3389/fncel.2022.971100] [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: 06/16/2022] [Accepted: 07/29/2022] [Indexed: 11/13/2022] Open
Abstract
This study aimed to explore the mechanism underlying cognitive dysfunction mediated by the lateral hypothalamic area (LHA) in a hypothalamic-hippocampal circuit in rats with lesion-induced hypothalamic obesity (HO). The HO model was established by electrically lesioning the hypothalamic nuclei. The open field (OP) test, Morris water maze (MWM), novel object recognition (NOR), and novel object location memory (NLM) tests were used to evaluate changes in cognition due to alterations in the hypothalamic-hippocampal circuit. Western blotting, immunohistochemical staining, and cholera toxin subunit B conjugated with Alexa Fluor 488 (CTB488) reverse tracer technology were used to determine synaptophysin (SYN), postsynaptic density protein 95 (PSD95), ionized calcium binding adaptor molecule 1 (Iba1), neuronal nuclear protein (NeuN), and Caspase3 expression levels and the hypothalamic-hippocampal circuit. In HO rats, severe obesity was associated with cognitive dysfunction after the lesion of the hypothalamus. Furthermore, neuronal apoptosis and activated microglia in the downstream of the lesion area (the LHA) induced microglial infiltration into the intact hippocampus via the LHA-hippocampal circuit, and the synapses engulfment in the hippocampus may be the underlying mechanism by which the remodeled microglial mediates memory impairments in HO rats. The HO rats exhibited microglial infiltration and synapse loss into the hippocampus from the lesioned LHA via the hypothalamic-hippocampal circuit. The underlying mechanisms of memory function may be related to the circuit.
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Affiliation(s)
- Chong Song
- Department of Neurosurgery, The Central Hospital of Dalian University of Technology, Dalian, China
- Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou, China
- *Correspondence: Chong Song,
| | - Wei Wei
- Department of Neurosurgery, The Central Hospital of Dalian University of Technology, Dalian, China
| | - Tong Wang
- Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou, China
- Department of Neurosurgery, The Third Hospital of Mianyang (Sichuan Mental Health Center), Mianyang, China
| | - Min Zhou
- Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Yunshi Li
- The First School of Clinical Medicine, Southern Medical University, Guangzhou, China
| | - Bing Xiao
- The First School of Clinical Medicine, Southern Medical University, Guangzhou, China
| | - Dongyi Huang
- The First School of Clinical Medicine, Southern Medical University, Guangzhou, China
| | - Junwei Gu
- Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Linyong Shi
- Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Junjie Peng
- Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou, China
- *Correspondence: Chong Song,
| | - Dianshi Jin
- Department of Neurosurgery, The Central Hospital of Dalian University of Technology, Dalian, China
- *Correspondence: Chong Song,
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