1
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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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2
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Miranda M, Silva A, Morici JF, Coletti MA, Belluscio M, Bekinschtein P. Retrieval of contextual memory can be predicted by CA3 remapping and is differentially influenced by NMDAR activity in rat hippocampus subregions. PLoS Biol 2024; 22:e3002706. [PMID: 38950066 PMCID: PMC11244845 DOI: 10.1371/journal.pbio.3002706] [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] [Received: 10/05/2023] [Revised: 07/12/2024] [Accepted: 06/12/2024] [Indexed: 07/03/2024] Open
Abstract
Episodic memory is essential to navigate in a changing environment by recalling past events, creating new memories, and updating stored information from experience. Although the mechanisms for acquisition and consolidation have been profoundly studied, much less is known about memory retrieval. Hippocampal spatial representations are key for retrieval of contextually guided episodic memories. Indeed, hippocampal place cells exhibit stable location-specific activity which is thought to support contextual memory, but can also undergo remapping in response to environmental changes. It is unclear if remapping is directly related to the expression of different episodic memories. Here, using an incidental memory recognition task in rats, we showed that retrieval of a contextually guided memory is reflected by the levels of CA3 remapping, demonstrating a clear link between external cues, hippocampal remapping, and episodic memory retrieval that guides behavior. Furthermore, we describe NMDARs as key players in regulating the balance between retrieval and memory differentiation processes by controlling the reactivation of specific memory traces. While an increase in CA3 NMDAR activity boosts memory retrieval, dentate gyrus NMDAR activity enhances memory differentiation. Our results contribute to understanding how the hippocampal circuit sustains a flexible balance between memory formation and retrieval depending on the environmental cues and the internal representations of the individual. They also provide new insights into the molecular mechanisms underlying the contributions of hippocampal subregions to generate this balance.
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Affiliation(s)
- Magdalena Miranda
- Laboratorio de Memoria y Cognición Molecular, Instituto de Neurociencia Cognitiva y Traslacional, CONICET-Fundación INECO-Universidad Favaloro, Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina
| | - Azul Silva
- Laboratorio Bases neuronales del comportamiento, Departamento de Ciencias Fisiológicas, Facultad de Ciencias Médicas, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina
- CONICET—Universidad de Buenos Aires, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay), Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina
| | - Juan Facundo Morici
- Laboratorio de Memoria y Cognición Molecular, Instituto de Neurociencia Cognitiva y Traslacional, CONICET-Fundación INECO-Universidad Favaloro, Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina
| | - Marcos Antonio Coletti
- Laboratorio Bases neuronales del comportamiento, Departamento de Ciencias Fisiológicas, Facultad de Ciencias Médicas, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina
- CONICET—Universidad de Buenos Aires, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay), Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina
| | - Mariano Belluscio
- Laboratorio Bases neuronales del comportamiento, Departamento de Ciencias Fisiológicas, Facultad de Ciencias Médicas, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina
- CONICET—Universidad de Buenos Aires, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay), Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina
| | - Pedro Bekinschtein
- Laboratorio de Memoria y Cognición Molecular, Instituto de Neurociencia Cognitiva y Traslacional, CONICET-Fundación INECO-Universidad Favaloro, Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina
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3
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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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4
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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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5
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Grella SL, Donaldson TN. Contextual memory engrams, and the neuromodulatory influence of the locus coeruleus. Front Mol Neurosci 2024; 17:1342622. [PMID: 38375501 PMCID: PMC10875109 DOI: 10.3389/fnmol.2024.1342622] [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: 11/22/2023] [Accepted: 01/19/2024] [Indexed: 02/21/2024] Open
Abstract
Here, we review the basis of contextual memory at a conceptual and cellular level. We begin with an overview of the philosophical foundations of traversing space, followed by theories covering the material bases of contextual representations in the hippocampus (engrams), exploring functional characteristics of the cells and subfields within. Next, we explore various methodological approaches for investigating contextual memory engrams, emphasizing plasticity mechanisms. This leads us to discuss the role of neuromodulatory inputs in governing these dynamic changes. We then outline a recent hypothesis involving noradrenergic and dopaminergic projections from the locus coeruleus (LC) to different subregions of the hippocampus, in sculpting contextual representations, giving a brief description of the neuroanatomical and physiological properties of the LC. Finally, we examine how activity in the LC influences contextual memory processes through synaptic plasticity mechanisms to alter hippocampal engrams. Overall, we find that phasic activation of the LC plays an important role in promoting new learning and altering mnemonic processes at the behavioral and cellular level through the neuromodulatory influence of NE/DA in the hippocampus. These findings may provide insight into mechanisms of hippocampal remapping and memory updating, memory processes that are potentially dysregulated in certain psychiatric and neurodegenerative disorders.
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Affiliation(s)
- Stephanie L. Grella
- MNEME Lab, Department of Psychology, Program in Neuroscience, Loyola University Chicago, Chicago, IL, United States
| | - Tia N. Donaldson
- Systems Neuroscience and Behavior Lab, Department of Psychology, The University of New Mexico, Albuquerque, NM, United States
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6
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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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7
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Levenstein D, Alvarez VA, Amarasingham A, Azab H, Chen ZS, Gerkin RC, Hasenstaub A, Iyer R, Jolivet RB, Marzen S, Monaco JD, Prinz AA, Quraishi S, Santamaria F, Shivkumar S, Singh MF, Traub R, Nadim F, Rotstein HG, Redish AD. On the Role of Theory and Modeling in Neuroscience. J Neurosci 2023; 43:1074-1088. [PMID: 36796842 PMCID: PMC9962842 DOI: 10.1523/jneurosci.1179-22.2022] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 12/14/2022] [Accepted: 12/18/2022] [Indexed: 02/18/2023] Open
Abstract
In recent years, the field of neuroscience has gone through rapid experimental advances and a significant increase in the use of quantitative and computational methods. This growth has created a need for clearer analyses of the theory and modeling approaches used in the field. This issue is particularly complex in neuroscience because the field studies phenomena that cross a wide range of scales and often require consideration at varying degrees of abstraction, from precise biophysical interactions to the computations they implement. We argue that a pragmatic perspective of science, in which descriptive, mechanistic, and normative models and theories each play a distinct role in defining and bridging levels of abstraction, will facilitate neuroscientific practice. This analysis leads to methodological suggestions, including selecting a level of abstraction that is appropriate for a given problem, identifying transfer functions to connect models and data, and the use of models themselves as a form of experiment.
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Affiliation(s)
- Daniel Levenstein
- Montreal Neurological Institute, McGill University, Montreal, Quebec H3A 2B4, Canada
| | - Veronica A Alvarez
- Laboratory on Neurobiology of Compulsive Behaviors, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland 20892
| | - Asohan Amarasingham
- Departments of Mathematics and Biology, City College and the Graduate Center, City University of New York, New York, New York 10032
| | - Habiba Azab
- Department of Neuroscience, Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota 55455
| | - Zhe S Chen
- Department of Psychiatry, Neuroscience & Physiology, New York University School of Medicine, New York, New York, 10016
| | - Richard C Gerkin
- School of Life Sciences, Arizona State University, Tempe, Arizona 85281
| | - Andrea Hasenstaub
- Department of Otolaryngology-Head and Neck Surgery, University of California San Francisco, San Francisco, California 94115
| | | | - Renaud B Jolivet
- Maastricht Centre for Systems Biology, Maastricht University, Maastricht, The Netherlands
| | - Sarah Marzen
- W. M. Keck Science Department, Pitzer, Scripps, and Claremont McKenna Colleges, Claremont, California 91711
| | - Joseph D Monaco
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland 21218
| | - Astrid A Prinz
- Department of Biology, Emory University, Atlanta, Georgia 30322
| | - Salma Quraishi
- Neuroscience, Developmental and Regnerative Biology Department, University of Texas at San Antonio, San Antonio, Texas 78249
| | - Fidel Santamaria
- Neuroscience, Developmental and Regnerative Biology Department, University of Texas at San Antonio, San Antonio, Texas 78249
| | - Sabyasachi Shivkumar
- Brain and Cognitive Sciences, University of Rochester, Rochester, New York 14627
| | - Matthew F Singh
- Department of Psychological & Brain Sciences, Department of Electrical & Systems Engineering, Washington University in St. Louis, St. Louis, Missouri 63112
| | - Roger Traub
- IBM T.J. Watson Research Center, AI Foundations, Yorktown Heights, New York 10598
| | - Farzan Nadim
- Montreal Neurological Institute, McGill University, Montreal, Quebec H3A 2B4, Canada
- Department of Otolaryngology-Head and Neck Surgery, University of California San Francisco, San Francisco, California 94115
| | - Horacio G Rotstein
- Montreal Neurological Institute, McGill University, Montreal, Quebec H3A 2B4, Canada
- Department of Otolaryngology-Head and Neck Surgery, University of California San Francisco, San Francisco, California 94115
| | - A David Redish
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455
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8
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Duvelle É, Grieves RM, van der Meer MAA. Temporal context and latent state inference in the hippocampal splitter signal. eLife 2023; 12:e82357. [PMID: 36622350 PMCID: PMC9829411 DOI: 10.7554/elife.82357] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 12/06/2022] [Indexed: 01/10/2023] Open
Abstract
The hippocampus is thought to enable the encoding and retrieval of ongoing experience, the organization of that experience into structured representations like contexts, maps, and schemas, and the use of these structures to plan for the future. A central goal is to understand what the core computations supporting these functions are, and how these computations are realized in the collective action of single neurons. A potential access point into this issue is provided by 'splitter cells', hippocampal neurons that fire differentially on the overlapping segment of trajectories that differ in their past and/or future. However, the literature on splitter cells has been fragmented and confusing, owing to differences in terminology, behavioral tasks, and analysis methods across studies. In this review, we synthesize consistent findings from this literature, establish a common set of terms, and translate between single-cell and ensemble perspectives. Most importantly, we examine the combined findings through the lens of two major theoretical ideas about hippocampal function: representation of temporal context and latent state inference. We find that unique signature properties of each of these models are necessary to account for the data, but neither theory, by itself, explains all of its features. Specifically, the temporal gradedness of the splitter signal is strong support for temporal context, but is hard to explain using state models, while its flexibility and task-dependence is naturally accounted for using state inference, but poses a challenge otherwise. These theories suggest a number of avenues for future work, and we believe their application to splitter cells is a timely and informative domain for testing and refining theoretical ideas about hippocampal function.
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Affiliation(s)
- Éléonore Duvelle
- Department of Psychological and Brain Sciences, Dartmouth CollegeHanoverUnited States
| | - Roddy M Grieves
- Department of Psychological and Brain Sciences, Dartmouth CollegeHanoverUnited States
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9
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Poh JH, Vu MAT, Stanek JK, Hsiung A, Egner T, Adcock RA. Hippocampal convergence during anticipatory midbrain activation promotes subsequent memory formation. Nat Commun 2022; 13:6729. [PMID: 36344524 PMCID: PMC9640528 DOI: 10.1038/s41467-022-34459-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 10/25/2022] [Indexed: 11/09/2022] Open
Abstract
The hippocampus has been a focus of memory research since H.M's surgery abolished his ability to form new memories, yet its mechanistic role in memory remains debated. Here, we identify a candidate memory mechanism: an anticipatory hippocampal "convergence state", observed while awaiting valuable information, and which predicts subsequent learning. During fMRI, participants viewed trivia questions eliciting high or low curiosity, followed seconds later by its answer. We reasoned that encoding success requires a confluence of conditions, so that hippocampal states more conducive to memory formation should converge in state space. To operationalize convergence of neural states, we quantified the typicality of multivoxel patterns in the medial temporal lobes during anticipation and encoding of trivia answers. We found that the typicality of anticipatory hippocampal patterns increased during high curiosity. Crucially, anticipatory hippocampal pattern typicality increased with dopaminergic midbrain activation and uniquely accounted for the association between midbrain activation and subsequent recall. We propose that hippocampal convergence states may complete a cascade from motivation and midbrain activation to memory enhancement, and may be a general predictor of memory formation.
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Affiliation(s)
- Jia-Hou Poh
- Center for Cognitive Neuroscience, Duke University, Durham, NC, USA.
| | - Mai-Anh T Vu
- Center for Cognitive Neuroscience, Duke University, Durham, NC, USA
- Department of Neurobiology, Duke University, Durham, NC, USA
- Department of Psychological & Brain Sciences, Boston University, Boston, MA, USA
| | - Jessica K Stanek
- Center for Cognitive Neuroscience, Duke University, Durham, NC, USA
- Department of Psychology & Neuroscience, Duke University, Durham, NC, USA
| | - Abigail Hsiung
- Center for Cognitive Neuroscience, Duke University, Durham, NC, USA
- Department of Psychology & Neuroscience, Duke University, Durham, NC, USA
| | - Tobias Egner
- Center for Cognitive Neuroscience, Duke University, Durham, NC, USA
- Department of Psychology & Neuroscience, Duke University, Durham, NC, USA
| | - R Alison Adcock
- Center for Cognitive Neuroscience, Duke University, Durham, NC, USA.
- Department of Neurobiology, Duke University, Durham, NC, USA.
- Department of Psychology & Neuroscience, Duke University, Durham, NC, USA.
- Department of Psychiatry & Behavioral Sciences, Duke University, Durham, NC, USA.
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10
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Rats use strategies to make object choices in spontaneous object recognition tasks. Sci Rep 2022; 12:16973. [PMID: 36216920 PMCID: PMC9550825 DOI: 10.1038/s41598-022-21537-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 09/28/2022] [Indexed: 12/29/2022] Open
Abstract
Rodent spontaneous object recognition (SOR) paradigms are widely used to study the mechanisms of complex memory in many laboratories. Due to the absence of explicit reinforcement in these tasks, there is an underlying assumption that object exploratory behaviour is 'spontaneous'. However, rodents can strategise, readily adapting their behaviour depending on the current information available and prior predications formed from learning and memory. Here, using the object-place-context (episodic-like) recognition task and novel analytic methods relying on multiple trials within a single session, we demonstrate that rats use a context-based or recency-based object recognition strategy for the same types of trials, depending on task conditions. Exposure to occasional ambiguous conditions changed animals' responses towards a recency-based preference. However, more salient and predictable conditions led to animals exploring objects on the basis of episodic novelty reliant on contextual information. The results have important implications for future research using SOR tasks, especially in the way experimenters design, analyse and interpret object recognition experiments in non-human animals.
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11
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Ross TW, Easton A. The Hippocampal Horizon: Constructing and Segmenting Experience for Episodic Memory. Neurosci Biobehav Rev 2021; 132:181-196. [PMID: 34826509 DOI: 10.1016/j.neubiorev.2021.11.038] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 11/19/2021] [Accepted: 11/22/2021] [Indexed: 12/29/2022]
Abstract
How do we recollect specific events that have occurred during continuous ongoing experience? There is converging evidence from non-human animals that spatially modulated cellular activity of the hippocampal formation supports the construction of ongoing events. On the other hand, recent human oriented event cognition models have outlined that our experience is segmented into discrete units, and that such segmentation can operate on shorter or longer timescales. Here, we describe a unification of how these dynamic physiological mechanisms of the hippocampus relate to ongoing externally and internally driven event segmentation, facilitating the demarcation of specific moments during experience. Our cross-species interdisciplinary approach offers a novel perspective in the way we construct and remember specific events, leading to the generation of many new hypotheses for future research.
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Affiliation(s)
- T W Ross
- Department of Psychology, Durham University, South Road, Durham, DH1 3LE, United Kingdom; Centre for Learning and Memory Processes, Durham University, United Kingdom.
| | - A Easton
- Department of Psychology, Durham University, South Road, Durham, DH1 3LE, United Kingdom; Centre for Learning and Memory Processes, Durham University, United Kingdom
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12
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Fetterhoff D, Sobolev A, Leibold C. Graded remapping of hippocampal ensembles under sensory conflicts. Cell Rep 2021; 36:109661. [PMID: 34525357 DOI: 10.1016/j.celrep.2021.109661] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 04/09/2021] [Accepted: 08/13/2021] [Indexed: 11/18/2022] Open
Abstract
Hippocampal place cells are thought to constitute a cognitive map of space derived from multimodal sensory inputs. Alteration of allocentric (visual) cues in a fixed environment is known to induce modulations of place cell activity to varying degrees from rate changes to global remapping. To determine how hippocampal ensembles combine multimodal sensory cues, we examine hippocampal CA1 remapping in Mongolian gerbils in a 1D virtual reality experiment, during which self-motion cues (locomotor, vestibular, and optic flow information) and allocentric visual cues are altered. We observe that self-motion cues are over-represented, but responsiveness to allocentric visual cues, although task-irrelevant, elicits both rate and global remapping in the hippocampal ensemble. We propose that remapping can be reconciled by considering global, partial, and rate remapping on a continuous scale on which the graded change of activity in the entire CA1 population can be interpreted as the expectancy about the animal's spatial environment.
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Affiliation(s)
- Dustin Fetterhoff
- Department Biologie II, Ludwig-Maximilians-Universität München, 82152 Munich, Germany.
| | - Andrey Sobolev
- Department Biologie II, Ludwig-Maximilians-Universität München, 82152 Munich, Germany
| | - Christian Leibold
- Department Biologie II, Ludwig-Maximilians-Universität München, 82152 Munich, Germany; Bernstein Center for Computational Neuroscience Munich, 82152 Munich, Germany
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13
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Dvorak D, Chung A, Park EH, Fenton AA. Dentate spikes and external control of hippocampal function. Cell Rep 2021; 36:109497. [PMID: 34348165 PMCID: PMC8369486 DOI: 10.1016/j.celrep.2021.109497] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 06/04/2021] [Accepted: 07/14/2021] [Indexed: 11/11/2022] Open
Abstract
Mouse hippocampus CA1 place-cell discharge typically encodes current location, but during slow gamma dominance (SGdom), when SG oscillations (30-50 Hz) dominate mid-frequency gamma oscillations (70-90 Hz) in CA1 local field potentials, CA1 discharge switches to represent distant recollected locations. We report that dentate spike type 2 (DSM) events initiated by medial entorhinal cortex II (MECII)→ dentate gyrus (DG) inputs promote SGdom and change excitation-inhibition coordinated discharge in DG, CA3, and CA1, whereas type 1 (DSL) events initiated by lateral entorhinal cortex II (LECII)→DG inputs do not. Just before SGdom, LECII-originating SG oscillations in DG and CA3-originating SG oscillations in CA1 phase and frequency synchronize at the DSM peak when discharge within DG and CA3 increases to promote excitation-inhibition cofiring within and across the DG→CA3→CA1 pathway. This optimizes discharge for the 5-10 ms DG-to-CA1 neuro-transmission that SGdom initiates. DSM properties identify extrahippocampal control of SGdom and a cortico-hippocampal mechanism that switches between memory-related modes of information processing.
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Affiliation(s)
- Dino Dvorak
- Center for Neural Science, New York University, New York, NY 10003, USA
| | - Ain Chung
- Center for Neural Science, New York University, New York, NY 10003, USA
| | - Eun Hye Park
- Center for Neural Science, New York University, New York, NY 10003, 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 10003, USA.
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14
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Grau-Perales AB, Gámiz F, Gallo M. Effect of hippocampal 6-OHDA lesions on the contextual modulation of taste recognition memory. Behav Brain Res 2021; 409:113320. [PMID: 33901433 DOI: 10.1016/j.bbr.2021.113320] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 04/19/2021] [Accepted: 04/20/2021] [Indexed: 12/23/2022]
Abstract
Taste recognition memory is evident in rodents because the initial neophobia to novel tastes attenuates across exposures as the taste becomes familiar and safe. This attenuation of taste neophobia (AN) is context-dependent and an auditory background change could induce the recovery of the neophobic response. The AN auditory context-dependency requires the hippocampal integrity but the neurochemical mechanisms underlying the interaction with the taste memory circuit remain unexplored. We have applied pharmacological intervention by 6-hidroxydopamine (6-OHDA) hippocampal lesion for assessing the role of catecholamines in the hippocampal system to Wistar rats that drank a novel 3% vinegar solution for several consecutive days. Additionally, we manipulated the auditory background as a context that could either change or remain constant across all the drinking sessions. We found that a disruption of the context-dependent AN was induced by intracerebral administration of 6-OHDA targeted to the ventral CA1 hippocampus (vCA1). We conclude that the ability of the auditory context to modulate taste recognition memory involves the catecholaminergic activity in the ventral hippocampal circuit for the proper acquisition of safe taste memory.
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Affiliation(s)
- Alejandro Borja Grau-Perales
- Department of Psychobiology, Institute of Neurosciences, Center for Biomedical Research (CIBM), University of Granada, Spain.
| | - Fernando Gámiz
- Department of Psychobiology, Institute of Neurosciences, Center for Biomedical Research (CIBM), University of Granada, Spain
| | - Milagros Gallo
- Department of Psychobiology, Institute of Neurosciences, Center for Biomedical Research (CIBM), University of Granada, Spain
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15
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Ahuja N, Lobellová V, Stuchlík A, Kelemen E. Navigation in a Space With Moving Objects: Rats Can Avoid Specific Locations Defined With Respect to a Moving Robot. Front Behav Neurosci 2020; 14:576350. [PMID: 33281571 PMCID: PMC7689095 DOI: 10.3389/fnbeh.2020.576350] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 10/13/2020] [Indexed: 11/13/2022] Open
Abstract
Animals can organize their behavior with respect to other moving animals or objects; when hunting or escaping a predator, when migrating in groups or during various social interactions. In rats, we aimed to characterize spatial behaviors relative to moving objects and to explore the cognitive mechanisms controlling these behaviors. Three groups of animals were trained to avoid a mild foot-shock delivered in one of three positions: either in front, on the left side, or on the right side of a moving robot. We showed the rats can recognize and avoid these specific areas. The avoidance behavior specific for the left or right side of the robot demonstrated animals not only react to "simple" stimuli such as increasing noise level or growing retinal image of an approaching object, but they process their spatial position relative to the object. Using an all-white robot without prominent visual patterns that would distinguish its different sides, we showed that the behavior does not depend on responses to prominent visual patterns, but that the rats can guide their navigation according to geometrical spatial relationship relative to the moving object. Rats' competence for navigation in space defined by a moving object resembles navigation abilities in stationary space. Recording of hippocampal single unit activity during rat's interaction with the robot proved feasibility of the task to uncover neuronal mechanism of this type of navigation.
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Affiliation(s)
- Nikhil Ahuja
- Institute of Physiology, Czech Academy of Sciences, Prague, Czechia.,Faculty of Science, Charles University, Prague, Czechia
| | | | - Aleš Stuchlík
- Institute of Physiology, Czech Academy of Sciences, Prague, Czechia
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16
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Sanders H, Wilson MA, Gershman SJ. Hippocampal remapping as hidden state inference. eLife 2020; 9:51140. [PMID: 32515352 PMCID: PMC7282808 DOI: 10.7554/elife.51140] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 05/09/2020] [Indexed: 11/13/2022] Open
Abstract
Cells in the hippocampus tuned to spatial location (place cells) typically change their tuning when an animal changes context, a phenomenon known as remapping. A fundamental challenge to understanding remapping is the fact that what counts as a ‘‘context change’’ has never been precisely defined. Furthermore, different remapping phenomena have been classified on the basis of how much the tuning changes after different types and degrees of context change, but the relationship between these variables is not clear. We address these ambiguities by formalizing remapping in terms of hidden state inference. According to this view, remapping does not directly reflect objective, observable properties of the environment, but rather subjective beliefs about the hidden state of the environment. We show how the hidden state framework can resolve a number of puzzles about the nature of remapping.
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Affiliation(s)
- Honi Sanders
- Center for Brains Minds and Machines, Harvard University, Cambridge, United States.,Picower Institute for Learning and Memory and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, United States
| | - Matthew A Wilson
- Center for Brains Minds and Machines, Harvard University, Cambridge, United States.,Picower Institute for Learning and Memory and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, United States
| | - Samuel J Gershman
- Center for Brains Minds and Machines, Harvard University, Cambridge, United States.,Department of Psychology, Harvard University, Cambridge, United States
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17
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Abstract
Contemporary brain research seeks to understand how cognition is reducible to neural activity. Crucially, much of this effort is guided by a scientific paradigm that views neural activity as essentially driven by external stimuli. In contrast, recent perspectives argue that this paradigm is by itself inadequate and that understanding patterns of activity intrinsic to the brain is needed to explain cognition. Yet, despite this critique, the stimulus-driven paradigm still dominates-possibly because a convincing alternative has not been clear. Here, we review a series of findings suggesting such an alternative. These findings indicate that neural activity in the hippocampus occurs in one of three brain states that have radically different anatomical, physiological, representational, and behavioral correlates, together implying different functional roles in cognition. This three-state framework also indicates that neural representations in the hippocampus follow a surprising pattern of organization at the timescale of ∼1 s or longer. Lastly, beyond the hippocampus, recent breakthroughs indicate three parallel states in the cortex, suggesting shared principles and brain-wide organization of intrinsic neural activity.
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Affiliation(s)
- Kenneth Kay
- Howard Hughes Medical Institute, Kavli Institute for Fundamental Neuroscience, Department of Physiology, University of California San Francisco, San Francisco, California
| | - Loren M Frank
- Howard Hughes Medical Institute, Kavli Institute for Fundamental Neuroscience, Department of Physiology, University of California San Francisco, San Francisco, California
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18
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Sheintuch L, Geva N, Baumer H, Rechavi Y, Rubin A, Ziv Y. Multiple Maps of the Same Spatial Context Can Stably Coexist in the Mouse Hippocampus. Curr Biol 2020; 30:1467-1476.e6. [PMID: 32220328 DOI: 10.1016/j.cub.2020.02.018] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 01/15/2020] [Accepted: 02/07/2020] [Indexed: 11/29/2022]
Abstract
Hippocampal place cells selectively fire when an animal traverses a particular location and are considered a neural substrate of spatial memory. Place cells were shown to change their activity patterns (remap) across different spatial contexts but to maintain their spatial tuning in a fixed familiar context. Here, we show that mouse hippocampal neurons can globally remap, forming multiple distinct representations (maps) of the same familiar environment, without any apparent changes in sensory input or behavior. Alternations between maps occurred only across separate visits to the environment, implying switching between distinct stable attractors in the hippocampal network. Importantly, the different maps were spatially informative and persistent over weeks, demonstrating that they can be reliably stored and retrieved from long-term memory. Taken together, our results suggest that a memory of a given spatial context could be associated with multiple distinct neuronal representations, rather than just one.
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Affiliation(s)
- Liron Sheintuch
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Nitzan Geva
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Hadas Baumer
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Yoav Rechavi
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Alon Rubin
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel.
| | - Yaniv Ziv
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel.
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19
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Nagele J, Herz AVM, Stemmler MB. Untethered firing fields and intermittent silences: Why grid-cell discharge is so variable. Hippocampus 2020; 30:367-383. [PMID: 32045073 DOI: 10.1002/hipo.23191] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 12/20/2019] [Accepted: 12/31/2019] [Indexed: 11/07/2022]
Abstract
Grid cells in medial entorhinal cortex are notoriously variable in their responses, despite the striking hexagonal arrangement of their spatial firing fields. Indeed, when the animal moves through a firing field, grid cells often fire much more vigorously than predicted or do not fire at all. The source of this trial-to-trial variability is not completely understood. By analyzing grid-cell spike trains from mice running in open arenas and on linear tracks, we characterize the phenomenon of "missed" firing fields using the statistical theory of zero inflation. We find that one major cause of grid-cell variability lies in the spatial representation itself: firing fields are not as strongly anchored to spatial location as the averaged grid suggests. In addition, grid fields from different cells drift together from trial to trial, regardless of whether the environment is real or virtual, or whether the animal moves in light or darkness. Spatial realignment across trials sharpens the grid representation, yielding firing fields that are more pronounced and significantly narrower. These findings indicate that ensembles of grid cells encode relative position more reliably than absolute position.
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Affiliation(s)
- Johannes Nagele
- Bernstein Center for Computational Neuroscience Munich and Faculty of Biology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Andreas V M Herz
- Bernstein Center for Computational Neuroscience Munich and Faculty of Biology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Martin B Stemmler
- Bernstein Center for Computational Neuroscience Munich and Faculty of Biology, Ludwig-Maximilians-Universität München, Munich, Germany
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20
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Kay K, Chung JE, Sosa M, Schor JS, Karlsson MP, Larkin MC, Liu DF, Frank LM. Constant Sub-second Cycling between Representations of Possible Futures in the Hippocampus. Cell 2020; 180:552-567.e25. [PMID: 32004462 DOI: 10.1016/j.cell.2020.01.014] [Citation(s) in RCA: 112] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 11/17/2019] [Accepted: 01/09/2020] [Indexed: 02/07/2023]
Abstract
Cognitive faculties such as imagination, planning, and decision-making entail the ability to represent hypothetical experience. Crucially, animal behavior in natural settings implies that the brain can represent hypothetical future experience not only quickly but also constantly over time, as external events continually unfold. To determine how this is possible, we recorded neural activity in the hippocampus of rats navigating a maze with multiple spatial paths. We found neural activity encoding two possible future scenarios (two upcoming maze paths) in constant alternation at 8 Hz: one scenario per ∼125-ms cycle. Further, we found that the underlying dynamics of cycling (both inter- and intra-cycle dynamics) generalized across qualitatively different representational correlates (location and direction). Notably, cycling occurred across moving behaviors, including during running. These findings identify a general dynamic process capable of quickly and continually representing hypothetical experience, including that of multiple possible futures.
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Affiliation(s)
- Kenneth Kay
- Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA 94158, USA; Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA.
| | - Jason E Chung
- Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA 94158, USA; Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Marielena Sosa
- Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA 94158, USA; Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Jonathan S Schor
- Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Mattias P Karlsson
- Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA 94158, USA; Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Margaret C Larkin
- Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA 94158, USA; Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Daniel F Liu
- Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA 94158, USA; Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Loren M Frank
- Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA 94158, USA; Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA; Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA.
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21
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Wang C, Chen X, Knierim JJ. Egocentric and allocentric representations of space in the rodent brain. Curr Opin Neurobiol 2019; 60:12-20. [PMID: 31794917 DOI: 10.1016/j.conb.2019.11.005] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 10/27/2019] [Accepted: 11/08/2019] [Indexed: 12/17/2022]
Abstract
Spatial signals are prevalent within the hippocampus and its neighboring regions. It is generally accepted that these signals are defined with respect to the external world (i.e., a world-centered, or allocentric, frame of reference). Recently, evidence of egocentric processing (i.e., self-centered, defined relative to the subject) in the extended hippocampal system has accumulated. These results support the idea that egocentric sensory information, derived from primary sensory cortical areas, may be transformed to allocentric representations that interact with the allocentric hippocampal system. We propose a framework to explain the implications of the egocentric-allocentric transformations to the functions of the medial temporal lobe memory system.
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Affiliation(s)
- Cheng Wang
- Guangdong Provincial Key Laboratory of Brain Connectome and Behavior, The Brain Cognition and Brain Disease Institute (BCBDI), Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China; Zanvyl Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, MD, USA.
| | - Xiaojing Chen
- Zanvyl Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, MD, USA
| | - James J Knierim
- Zanvyl Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, MD, USA; Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD, USA.
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22
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Krajcovic B, Fajnerova I, Horacek J, Kelemen E, Kubik S, Svoboda J, Stuchlik A. Neural and neuronal discoordination in schizophrenia: From ensembles through networks to symptoms. Acta Physiol (Oxf) 2019; 226:e13282. [PMID: 31002202 DOI: 10.1111/apha.13282] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 03/27/2019] [Accepted: 04/12/2019] [Indexed: 12/22/2022]
Abstract
Despite the substantial knowledge accumulated by past research, the exact mechanisms of the pathogenesis of schizophrenia and causal treatments still remain unclear. Deficits of cognition and information processing in schizophrenia are today often viewed as the primary and core symptoms of this devastating disorder. These deficits likely result from disruptions in the coordination of neuronal and neural activity. The aim of this review is to bring together convergent evidence of discoordinated brain circuits in schizophrenia at multiple levels of resolution, ranging from principal cells and interneurons, neuronal ensembles and local circuits, to large-scale brain networks. We show how these aberrations could underlie deficits in cognitive control and other higher order cognitive-behavioural functions. Converging evidence from both animal models and patients with schizophrenia is presented in an effort to gain insight into common features of deficits in the brain information processing in this disorder, marked by disruption of several neurotransmitter and signalling systems and severe behavioural outcomes.
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Affiliation(s)
- Branislav Krajcovic
- Department of Neurophysiology of Memory Institute of Physiology of the Czech Academy of Sciences Prague Czech Republic
- Third Faculty of Medicine Charles University Prague Czech Republic
| | - Iveta Fajnerova
- Department of Neurophysiology of Memory Institute of Physiology of the Czech Academy of Sciences Prague Czech Republic
- Research Programme 3 - Applied Neurosciences and Brain Imaging National Institute of Mental Health Klecany Czech Republic
| | - Jiri Horacek
- Third Faculty of Medicine Charles University Prague Czech Republic
- Research Programme 3 - Applied Neurosciences and Brain Imaging National Institute of Mental Health Klecany Czech Republic
| | - Eduard Kelemen
- Research Programme 1 - Experimental Neurobiology National Institute of Mental Health Klecany Czech Republic
| | - Stepan Kubik
- Department of Neurophysiology of Memory Institute of Physiology of the Czech Academy of Sciences Prague Czech Republic
| | - Jan Svoboda
- Department of Neurophysiology of Memory Institute of Physiology of the Czech Academy of Sciences Prague Czech Republic
| | - Ales Stuchlik
- Department of Neurophysiology of Memory Institute of Physiology of the Czech Academy of Sciences Prague Czech Republic
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23
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Impaired cerebellar Purkinje cell potentiation generates unstable spatial map orientation and inaccurate navigation. Nat Commun 2019; 10:2251. [PMID: 31113954 PMCID: PMC6529420 DOI: 10.1038/s41467-019-09958-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 04/05/2019] [Indexed: 12/29/2022] Open
Abstract
Cerebellar activity supported by PKC-dependent long-term depression in Purkinje cells (PCs) is involved in the stabilization of self-motion based hippocampal representation, but the existence of cerebellar processes underlying integration of allocentric cues remains unclear. Using mutant-mice lacking PP2B in PCs (L7-PP2B mice) we here assess the role of PP2B-dependent PC potentiation in hippocampal representation and spatial navigation. L7-PP2B mice display higher susceptibility to spatial map instability relative to the allocentric cue and impaired allocentric as well as self-motion goal-directed navigation. These results indicate that PP2B-dependent potentiation in PCs contributes to maintain a stable hippocampal representation of a familiar environment in an allocentric reference frame as well as to support optimal trajectory toward a goal during navigation. It is known that Purkinje cell PKC-dependent depression is involved in the stabilization of self-motion based hippocampal representation. Here the authors describe decreased stability of hippocampal place cells based on allocentric cues in mice lacking Purkinje cell PP2B-dependent potentiation.
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24
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O'Reilly KC, Perica MI, Fenton AA. Synaptic plasticity/dysplasticity, process memory and item memory in rodent models of mental dysfunction. Schizophr Res 2019; 207:22-36. [PMID: 30174252 PMCID: PMC6395534 DOI: 10.1016/j.schres.2018.08.025] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 08/14/2018] [Accepted: 08/14/2018] [Indexed: 12/21/2022]
Abstract
Activity-dependent changes in the effective connection strength of synapses are a fundamental feature of a nervous system. This so-called synaptic plasticity is thought to underlie storage of information in memory and has been hypothesized to be crucial for the effects of cognitive behavioral therapy. Synaptic plasticity stores information in a neural network, creating a trace of neural activity from past experience. The plasticity can also change the behavior of the network so the network can differentially transform/compute information in future activations. We discuss these two related but separable functions of synaptic plasticity; one we call "item memory" as it represents and stores items of information in memory, the other we call "process memory" as it encodes and stores functions such as computations to modify network information processing capabilities. We review evidence of item and process memory operations in behavior and evidence that experience modifies the brain's functional networks. We discuss neurodevelopmental rodent models relevant for understanding mental illness and compare two models in which one model, neonatal ventral hippocampal lesion (NVHL) has beneficial adult outcomes after being exposed to an adolescent cognitive experience that is potentially similar to cognitive behavioral therapy. The other model, gestational day 17 methylazoxymethanol acetate (GD17-MAM), does not benefit from the same adolescent cognitive experience. We propose that process memory is altered by early cognitive experience in NVHL rats but not in GD17-MAM rats, and discuss how dysplasticity factors may contribute to the differential adult outcomes after early cognitive experience in the NVHL and MAM models.
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Affiliation(s)
- Kally C O'Reilly
- Center for Neural Science, New York University, New York, NY 10003, USA.
| | - Maria I Perica
- Center for Neural Science, New York University, New York, NY 10003, USA
| | - André A Fenton
- Center for Neural Science, New York University, New York, NY 10003, USA; Neuroscience Institute at the New York University Langone Medical Center, New York, NY 10016, USA; Department of Physiology & Pharmacology, Robert F. Furchgott Center for Neuroscience, State University of New York, Downstate Medical Center, Brooklyn, NY 11203, USA.
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25
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Madar AD, Ewell LA, Jones MV. Pattern separation of spiketrains in hippocampal neurons. Sci Rep 2019; 9:5282. [PMID: 30918288 PMCID: PMC6437159 DOI: 10.1038/s41598-019-41503-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 03/08/2019] [Indexed: 11/30/2022] Open
Abstract
Pattern separation is a process that minimizes overlap between patterns of neuronal activity representing similar experiences. Theoretical work suggests that the dentate gyrus (DG) performs this role for memory processing but a direct demonstration is lacking. One limitation is the difficulty to measure DG inputs and outputs simultaneously. To rigorously assess pattern separation by DG circuitry, we used mouse brain slices to stimulate DG afferents and simultaneously record DG granule cells (GCs) and interneurons. Output spiketrains of GCs are more dissimilar than their input spiketrains, demonstrating for the first time temporal pattern separation at the level of single neurons in the DG. Pattern separation is larger in GCs than in fast-spiking interneurons and hilar mossy cells, and is amplified in CA3 pyramidal cells. Analysis of the neural noise and computational modelling suggest that this form of pattern separation is not explained by simple randomness and arises from specific presynaptic dynamics. Overall, by reframing the concept of pattern separation in dynamic terms and by connecting it to the physiology of different types of neurons, our study offers a new window of understanding in how hippocampal networks might support episodic memory.
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Affiliation(s)
- Antoine D Madar
- Department of Neuroscience, University of Wisconsin, Madison, WI, 53705, USA. .,Department of Neurobiology, Grossman Institute for Neuroscience, Quantitative Biology and Human Behavior, University of Chicago, Chicago, IL, 60637, USA.
| | - Laura A Ewell
- Department of Neuroscience, University of Wisconsin, Madison, WI, 53705, USA.,Institute of Experimental Epileptology and Cognition Research, University of Bonn - Medical Center, Bonn, Germany
| | - Mathew V Jones
- Department of Neuroscience, University of Wisconsin, Madison, WI, 53705, USA
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26
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Sanders H, Ji D, Sasaki T, Leutgeb JK, Wilson MA, Lisman JE. Temporal coding and rate remapping: Representation of nonspatial information in the hippocampus. Hippocampus 2018; 29:111-127. [PMID: 30129985 DOI: 10.1002/hipo.23020] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 07/19/2018] [Accepted: 08/14/2018] [Indexed: 12/11/2022]
Abstract
Hippocampal place cells represent nonspatial information through a process called rate remapping, which involves a change in the firing rate of a place cell without changes in its spatial specificity. However, many hippocampal phenomena occur on very short time scales over which long-term average firing rates are not an appropriate description of activity. To understand how rate remapping relates to fine-scale temporal firing phenomena, we asked how rate remapping affected burst firing and trial-to-trial spike count variability. In addition, we looked at how rate remapping relates to the theta-frequency oscillations of the hippocampus, which are thought to temporally organize firing on time scales faster than 100 ms. We found that theta phase coding was preserved through changes in firing rate due to rate remapping. Interestingly, rate remapping in CA1 in response to task demands preferentially occurred during the first half of the theta cycle. The other half of the theta cycle contained preferential expression of phase precession, a phenomenon associated with place cell sequences, in agreement with previous results. This difference of place cell coding during different halves of the theta cycle supports recent theoretical suggestions that different processes occur during the two halves of the theta cycle. The differentiation between the halves of the theta cycle was not clear in recordings from CA3 during rate remapping induced by task-irrelevant sensory changes. These findings provide new insight into the way that temporal coding is utilized in the hippocampus and how rate remapping is expressed through that temporal code.
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Affiliation(s)
- Honi Sanders
- Volen Center for Complex Systems, Brandeis University, Waltham, Massachusetts.,Neuroscience Program, Brandeis University, Waltham, Massachusetts
| | - Daoyun Ji
- Department of Brain and Cognitive Sciences, Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Takuya Sasaki
- Division of Biological Sciences, Neurobiology Section and Center for Neural Circuits and Behavior, University of California, San Diego, California
| | - Jill K Leutgeb
- Division of Biological Sciences, Neurobiology Section and Center for Neural Circuits and Behavior, University of California, San Diego, California
| | - Matthew A Wilson
- Department of Brain and Cognitive Sciences, Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - John E Lisman
- Volen Center for Complex Systems, Brandeis University, Waltham, Massachusetts.,Department of Biology, Brandeis University, Waltham, Massachusetts
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27
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Abstract Representation of Prospective Reward in the Hippocampus. J Neurosci 2018; 38:10093-10101. [PMID: 30282732 DOI: 10.1523/jneurosci.0719-18.2018] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 09/21/2018] [Accepted: 09/25/2018] [Indexed: 11/21/2022] Open
Abstract
Motivation enhances memory by increasing hippocampal engagement during encoding. However, whether such increased hippocampal activation reflects encoding of the value of highly rewarding events per se is less understood. Here, using a monetary incentive encoding task with a novel manipulation, we tested in humans whether the hippocampus represents abstract reward value, independent of perceptual content. During functional MRI scanning, men and women studied object pairs, each preceded by a monetary reward cue indicating the amount of money they would receive if they successfully remembered the object pair at test. Reward cues varied on both the level of reward (penny, dime, and dollar) and visual form (picture or word) across trials to dissociate hippocampal responses to reward value from those reflecting the perceptual properties of the cues. Behaviorally, participants remembered pairs associated with the high reward (dollar) more often than pairs associated with lower rewards. Neural pattern-similarity analysis revealed that hippocampal and parahippocampal cortex activation patterns discriminated between cues of different value regardless of their visual form, and that hippocampal discrimination of value was most pronounced in participants who showed the greatest behavioral sensitivity to reward. Strikingly, hippocampal patterns were most distinct for reward cues that differed in value but had similar visual appearance, consistent with theoretical proposals of hippocampal-pattern differentiation of competing representations. Our data illustrate how contextual representations within the hippocampus go beyond space and time to include information about the motivational salience of events, with hippocampal reward coding tracking the motivational impact on later memory.SIGNIFICANCE STATEMENT Motivation, such as the promise of future rewards, enhances hippocampal engagement during encoding and promotes successful retention of events associated with valuable rewards. However, whether the hippocampus explicitly encodes reward value, dissociable from sensory information, is unclear. Here, we show that the hippocampus forms abstract representation of valuable rewards, encoding conceptual rather than perceptual information about the motivational context of individual events. Reward representation within the hippocampus is associated with preferential retention of high-value events in memory. Furthermore, we show that hippocampal-pattern differentiation serves to emphasize differences between visually similar events with distinct motivational salience. Collectively, these findings indicate that hippocampal contextual representations enable individuals to distinguish the motivational value of events, leading to prioritized encoding of significant memories.
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Li M, Xie K, Kuang H, Liu J, Wang D, Fox GE, Shi Z, Chen L, Zhao F, Mao Y, Tsien JZ. Neural Coding of Cell Assemblies via Spike-Timing Self-Information. Cereb Cortex 2018; 28:2563-2576. [PMID: 29688285 PMCID: PMC5998964 DOI: 10.1093/cercor/bhy081] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Indexed: 12/31/2022] Open
Abstract
Cracking brain's neural code is of general interest. In contrast to the traditional view that enormous spike variability in resting states and stimulus-triggered responses reflects noise, here, we examine the "Neural Self-Information Theory" that the interspike-interval (ISI), or the silence-duration between 2 adjoining spikes, carries self-information that is inversely proportional to its variability-probability. Specifically, higher-probability ISIs convey minimal information because they reflect the ground state, whereas lower-probability ISIs carry more information, in the form of "positive" or "negative surprisals," signifying the excitatory or inhibitory shifts from the ground state, respectively. These surprisals serve as the quanta of information to construct temporally coordinated cell-assembly ternary codes representing real-time cognitions. Accordingly, we devised a general decoding method and unbiasedly uncovered 15 cell assemblies underlying different sleep cycles, fear-memory experiences, spatial navigation, and 5-choice serial-reaction time (5CSRT) visual-discrimination behaviors. We further revealed that robust cell-assembly codes were generated by ISI surprisals constituted of ~20% of the skewed ISI gamma-distribution tails, conforming to the "Pareto Principle" that specifies, for many events-including communication-roughly 80% of the output or consequences come from 20% of the input or causes. These results demonstrate that real-time neural coding arises from the temporal assembly of neural-clique members via silence variability-based self-information codes.
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Affiliation(s)
- Meng Li
- Brain and Behavior Discovery Institute and Department of Neurology, Medical College of Georgia at Augusta University, Augusta, GA, USA
| | - Kun Xie
- Brain and Behavior Discovery Institute and Department of Neurology, Medical College of Georgia at Augusta University, Augusta, GA, USA
- The Brain Decoding Center, Banna Biomedical Research Institute, Yunnan Province Academy of Science and Technology, Xi-Shuang-Ban-Na Prefecture, Yunnan, China
| | - Hui Kuang
- Brain and Behavior Discovery Institute and Department of Neurology, Medical College of Georgia at Augusta University, Augusta, GA, USA
| | - Jun Liu
- Brain and Behavior Discovery Institute and Department of Neurology, Medical College of Georgia at Augusta University, Augusta, GA, USA
| | - Deheng Wang
- Brain and Behavior Discovery Institute and Department of Neurology, Medical College of Georgia at Augusta University, Augusta, GA, USA
- The Brain Decoding Center, Banna Biomedical Research Institute, Yunnan Province Academy of Science and Technology, Xi-Shuang-Ban-Na Prefecture, Yunnan, China
| | - Grace E Fox
- Brain and Behavior Discovery Institute and Department of Neurology, Medical College of Georgia at Augusta University, Augusta, GA, USA
| | - Zhifeng Shi
- Department of Neuropathology, Huashan Hospital, Fudan University, Shanghai, China
| | - Liang Chen
- Department of Neuropathology, Huashan Hospital, Fudan University, Shanghai, China
| | - Fang Zhao
- Brain and Behavior Discovery Institute and Department of Neurology, Medical College of Georgia at Augusta University, Augusta, GA, USA
- The Brain Decoding Center, Banna Biomedical Research Institute, Yunnan Province Academy of Science and Technology, Xi-Shuang-Ban-Na Prefecture, Yunnan, China
| | - Ying Mao
- Department of Neuropathology, Huashan Hospital, Fudan University, Shanghai, China
| | - Joe Z Tsien
- Brain and Behavior Discovery Institute and Department of Neurology, Medical College of Georgia at Augusta University, Augusta, GA, USA
- The Brain Decoding Center, Banna Biomedical Research Institute, Yunnan Province Academy of Science and Technology, Xi-Shuang-Ban-Na Prefecture, Yunnan, China
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Szczurowska E, Ahuja N, Jiruška P, Kelemen E, Stuchlík A. Impairment of neural coordination in hippocampal neuronal ensembles after a psychotomimetic dose of dizocilpine. Prog Neuropsychopharmacol Biol Psychiatry 2018; 81:275-283. [PMID: 28935586 DOI: 10.1016/j.pnpbp.2017.09.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 09/15/2017] [Accepted: 09/16/2017] [Indexed: 11/19/2022]
Abstract
The discoordination hypothesis of schizophrenia posits discoordination of neural activity as the central mechanism that underlies some psychotic symptoms (including 'hallmark' cognitive symptoms) of schizophrenia. To test this proposition, we studied the activity of hippocampal neurons in urethane anesthetized Long Evans rats after 0.15mg/kg dizocilpine (MK-801), an N-Methyl-d-aspartate (NMDA) glutamate receptor antagonist, which can cause psychotic symptoms in humans and cognitive control impairments in animals. We observed that MK-801 altered the temporal coordination, but not rate, of neuronal firing. Coactivation between neurons increased, driven primarily by increased coincident firing of cell pairs that did not originally fire together before MK-801 injection. Increased pairwise coactivation manifested as disorganized discharge on the level of neuronal ensembles, which in turn could lead to disorganization in information processing. Disorganization of neuronal activity after a psychotomimetic dose of MK-801 supports the discoordination hypothesis of psychosis.
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Affiliation(s)
- Ewa Szczurowska
- National Institute of Mental Health, Topolová 748, 250 67 Klecany, Czech Republic
| | - Nikhil Ahuja
- Department of Neurophysiology of Memory and Institute of Physiology, Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague, Czech Republic
| | - Přemysl Jiruška
- Department of Developmental Epileptology, Institute of Physiology, Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague, Czech Republic
| | - Eduard Kelemen
- National Institute of Mental Health, Topolová 748, 250 67 Klecany, Czech Republic.
| | - Aleš Stuchlík
- Department of Neurophysiology of Memory and Institute of Physiology, Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague, Czech Republic.
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Normal CA1 Place Fields but Discoordinated Network Discharge in a Fmr1-Null Mouse Model of Fragile X Syndrome. Neuron 2018; 97:684-697.e4. [PMID: 29358017 DOI: 10.1016/j.neuron.2017.12.043] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 10/06/2017] [Accepted: 12/27/2017] [Indexed: 11/21/2022]
Abstract
Silence of FMR1 causes loss of fragile X mental retardation protein (FMRP) and dysregulated translation at synapses, resulting in the intellectual disability and autistic symptoms of fragile X syndrome (FXS). Synaptic dysfunction hypotheses for how intellectual disabilities like cognitive inflexibility arise in FXS predict impaired neural coding in the absence of FMRP. We tested the prediction by comparing hippocampus place cells in wild-type and FXS-model mice. Experience-driven CA1 synaptic function and synaptic plasticity changes are excessive in Fmr1-null mice, but CA1 place fields are normal. However, Fmr1-null discharge relationships to local field potential oscillations are abnormally weak, stereotyped, and homogeneous; also, discharge coordination within Fmr1-null place cell networks is weaker and less reliable than wild-type. Rather than disruption of single-cell neural codes, these findings point to invariant tuning of single-cell responses and inadequate discharge coordination within neural ensembles as a pathophysiological basis of cognitive inflexibility in FXS. VIDEO ABSTRACT.
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Dvorak D, Radwan B, Sparks FT, Talbot ZN, Fenton AA. Control of recollection by slow gamma dominating mid-frequency gamma in hippocampus CA1. PLoS Biol 2018; 16:e2003354. [PMID: 29346381 PMCID: PMC5790293 DOI: 10.1371/journal.pbio.2003354] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 01/30/2018] [Accepted: 12/28/2017] [Indexed: 11/19/2022] Open
Abstract
Behavior is used to assess memory and cognitive deficits in animals like Fmr1-null mice that model Fragile X Syndrome, but behavior is a proxy for unknown neural events that define cognitive variables like recollection. We identified an electrophysiological signature of recollection in mouse dorsal Cornu Ammonis 1 (CA1) hippocampus. During a shocked-place avoidance task, slow gamma (SG) (30–50 Hz) dominates mid-frequency gamma (MG) (70–90 Hz) oscillations 2–3 s before successful avoidance, but not failures. Wild-type (WT) but not Fmr1-null mice rapidly adapt to relocating the shock; concurrently, SG/MG maxima (SGdom) decrease in WT but not in cognitively inflexible Fmr1-null mice. During SGdom, putative pyramidal cell ensembles represent distant locations; during place avoidance, these are avoided places. During shock relocation, WT ensembles represent distant locations near the currently correct shock zone, but Fmr1-null ensembles represent the formerly correct zone. These findings indicate that recollection occurs when CA1 SG dominates MG and that accurate recollection of inappropriate memories explains Fmr1-null cognitive inflexibility. Behavior is often used as proxy to study memory and cognitive deficits in animals like Fmr1-KO mice that model Fragile X Syndrome, the most prevalent single-gene cause of intellectual disability and autism. However, it is unclear what neural events define cognitive variables like recollection of memory and cognitive inflexibility. We identified a signature of recollection in the local field potentials of mouse dorsal CA1 hippocampus. When mice on a rotating platform avoided an invisible, fixed shock zone, slow gamma (30–50 Hz) oscillations dominated mid-frequency gamma (70–90 Hz) oscillations (SGdom) 2–3 s before mice successfully avoided the shock zone. Wild-type but not Fmr1-KO mice adapt to relocating the shock zone; concurrently, SGdom decreases in wild-type but not in cognitively inflexible Fmr1-KO mice. During SGdom, principal cell ensembles represent distant locations; during place avoidance, these are avoided places in the shock zone vicinity. During shock relocation, wild-type ensembles encode distant locations near the currently correct shock zone, but Fmr1-KO ensembles manifest representational inflexibility, encoding the formerly correct zone. These findings suggest evidence for competition amongst CA1 inputs for CA1 information-processing modes and indicate that recollection occurs when CA1 slow gamma dominates mid-frequency gamma and that accurate recollection of inappropriate memories explains Fmr1-KO cognitive inflexibility.
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Affiliation(s)
- Dino Dvorak
- Center for Neural Science, New York University, New York, New York, United States of America
| | - Basma Radwan
- Center for Neural Science, New York University, New York, New York, United States of America
| | - Fraser T. Sparks
- Center for Neural Science, New York University, New York, New York, United States of America
| | - Zoe Nicole Talbot
- School of Medicine, New York University, New York, New York, United States of America
| | - André A. Fenton
- Center for Neural Science, New York University, New York, New York, United States of America
- Neuroscience Institute at the New York University Langone Medical Center, New York, New York, United States of America
- Department of Physiology and Pharmacology, The Robert F. Furchgott Center for Neural & Behavioral Science, State University of New York, Downstate Medical Center, Brooklyn, New York, United States of America
- * E-mail:
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Phencyclidine Discoordinates Hippocampal Network Activity But Not Place Fields. J Neurosci 2017; 37:12031-12049. [PMID: 29118102 DOI: 10.1523/jneurosci.0630-17.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 09/22/2017] [Accepted: 10/17/2017] [Indexed: 11/21/2022] Open
Abstract
We used the psychotomimetic phencyclidine (PCP) to investigate the relationships among cognitive behavior, coordinated neural network function, and information processing within the hippocampus place cell system. We report in rats that PCP (5 mg/kg, i.p.) impairs a well learned, hippocampus-dependent place avoidance behavior in rats that requires cognitive control even when PCP is injected directly into dorsal hippocampus. PCP increases 60-100 Hz medium-freguency gamma oscillations in hippocampus CA1 and these increases correlate with the cognitive impairment caused by systemic PCP administration. PCP discoordinates theta-modulated medium-frequency and slow gamma oscillations in CA1 LFPs such that medium-frequency gamma oscillations become more theta-organized than slow gamma oscillations. CA1 place cell firing fields are preserved under PCP, but the drug discoordinates the subsecond temporal organization of discharge among place cells. This discoordination causes place cell ensemble representations of a familiar space to cease resembling pre-PCP representations despite preserved place fields. These findings point to the cognitive impairments caused by PCP arising from neural discoordination. PCP disrupts the timing of discharge with respect to the subsecond timescales of theta and gamma oscillations in the LFP. Because these oscillations arise from local inhibitory synaptic activity, these findings point to excitation-inhibition discoordination as the root of PCP-induced cognitive impairment.SIGNIFICANCE STATEMENT Hippocampal neural discharge is temporally coordinated on timescales of theta and gamma oscillations in the LFP and the discharge of a subset of pyramidal neurons called "place cells" is spatially organized such that discharge is restricted to locations called a cell's "place field." Because this temporal coordination and spatial discharge organization is thought to represent spatial knowledge, we used the psychotomimetic phencyclidine (PCP) to disrupt cognitive behavior and assess the importance of neural coordination and place fields for spatial cognition. PCP impaired the judicious use of spatial information and discoordinated hippocampal discharge without disrupting firing fields. These findings dissociate place fields from spatial cognitive behavior and suggest that hippocampus discharge coordination is crucial to spatial cognition.
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Corticosteroid-induced dendrite loss and behavioral deficiencies can be blocked by activation of Abl2/Arg kinase. Mol Cell Neurosci 2017; 85:226-234. [PMID: 29107098 DOI: 10.1016/j.mcn.2017.10.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 10/25/2017] [Indexed: 12/31/2022] Open
Abstract
Stressor exposure induces neuronal remodeling in specific brain regions. Given the persistence of stress-related illnesses, key next steps in determining the contributions of neural structure to mental health are to identify cell types that fail to recover from stressor exposure and to identify "trigger points" and molecular underpinnings of stress-related neural degeneration. We evaluated dendrite arbor structure on hippocampal CA1 pyramidal neurons before, during, and following prolonged exposure to one key mediator of the stress response - corticosterone (cortisol in humans). Basal dendrite arbors progressively simplified during a 3-week exposure period, and failed to recover when corticosterone was withdrawn. Corticosterone exposure decreased levels of the dendrite stabilization factor Abl2/Arg nonreceptor tyrosine kinase and phosphorylation of its substrates p190RhoGAP and cortactin within 11days, suggesting that disruption of Arg-mediated signaling may trigger dendrite arbor atrophy and, potentially, behavioral abnormalities resulting from corticosterone exposure. To test this, we administered the novel, bioactive Arg kinase activator, 5-(1,3-diaryl-1H-pyrazol-4-yl)hydantoin, 5-[3-(4-fluorophenyl)-1-phenyl-1H-pyrazol-4-yl]-2,4-imidazolidinedione (DPH), in conjunction with corticosterone. We found that repeated treatment corrected CA1 arbor structure, otherwise simplified by corticosterone. DPH also corrected corticosterone-induced errors in a hippocampal-dependent reversal learning task and anhedonic-like behavior. Thus, pharmacological compounds that target cytoskeletal regulators, rather than classical neurotransmitter systems, may interfere with stress-associated cognitive decline and mental health concerns.
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Lisman J, Buzsáki G, Eichenbaum H, Nadel L, Ranganath C, Redish AD. Viewpoints: how the hippocampus contributes to memory, navigation and cognition. Nat Neurosci 2017; 20:1434-1447. [PMID: 29073641 PMCID: PMC5943637 DOI: 10.1038/nn.4661] [Citation(s) in RCA: 386] [Impact Index Per Article: 55.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The hippocampus serves a critical function in memory, navigation, and cognition. Nature Neuroscience asked John Lisman to lead a group of researchers in a dialog on shared and distinct viewpoints on the hippocampus. There has been a long history of studying the hippocampus, but recent work has made it possible to study the cellular and network basis of defined operations—operations that include cognitive processes that have been otherwise difficult to study (see Box 1 for useful terminology). These operations deal with the context-dependent representation of complex memories, the role of mental exploration based on imagined rather than real movements, and the use of recalled information for navigation and decision-making. The progress that has been made in understanding the hippocampus has motivated the study of other brain regions that provide hippocampal input or receive hippocampal output; the hippocampus is thus serving as a nucleating point for the larger goal of understanding the neural codes that allow inter-regional communication and more generally, understanding how memory-guided behavior is achieved by large scale integration of brain regions. In generating a discussion among experts in the study of the cognitive processes of the hippocampus, the editors and I have posed questions that probe important principles of hippocampal function. We hope that the resulting discussion will make clear to readers the progress that has been made, while also identifying issues where consensus has not yet been achieved and that should be pursued in future research. – John Lisman
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Affiliation(s)
- John Lisman
- Department of Biology at Brandeis University, Waltham, Massachusetts, USA
| | - György Buzsáki
- NYU Neuroscience Institute at New York University, New York, New York, USA
| | - Howard Eichenbaum
- Center for Memory and Brain at Boston University, Boston, Massachusetts, USA
| | - Lynn Nadel
- Department of Psychology and Cognitive Science Program at University of Arizona, Tucson, Arizona, USA
| | - Charan Ranganath
- Center for Neuroscience and Department of Psychology at the University of California, Davis, California, USA
| | - A David Redish
- Department of Neuroscience at the University of Minnesota, Minneapolis, Minnesota, USA
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35
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Flexible weighting of diverse inputs makes hippocampal function malleable. Neurosci Lett 2017; 680:13-22. [PMID: 28587901 DOI: 10.1016/j.neulet.2017.05.063] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 05/29/2017] [Accepted: 05/29/2017] [Indexed: 12/17/2022]
Abstract
Classic theories of hippocampal function have emphasized its role as a dedicated memory system, but recent research has shown that it contributes broadly to many aspects of cognition, including attention and perception. We propose that the reason the hippocampus plays such a broad role in cognition is that its function is particularly malleable. We argue that this malleability arises because the hippocampus receives diverse anatomical inputs and these inputs are flexibly weighted based on behavioral goals. We discuss examples of how hippocampal representations can be flexibly weighted, focusing on hippocampal modulation by attention. Finally, we suggest some general neural mechanisms and core hippocampal computations that may enable the hippocampus to support diverse cognitive functions, including attention, perception, and memory. Together, this work suggests that great progress can and has been made in understanding the hippocampus by considering how the domain-general computations it performs allow it to dynamically contribute to many different behaviors.
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Svoboda J, Lobellová V, Popelíková A, Ahuja N, Kelemen E, Stuchlík A. Transient inactivation of the anterior cingulate cortex in rats disrupts avoidance of a dynamic object. Neurobiol Learn Mem 2017; 139:144-148. [PMID: 28065714 DOI: 10.1016/j.nlm.2017.01.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2016] [Revised: 12/05/2016] [Accepted: 01/04/2017] [Indexed: 11/20/2022]
Abstract
Although animals often learn and monitor the spatial properties of relevant moving objects such as conspecifics and predators to properly organize their own spatial behavior, the underlying brain substrate has received little attention and hence remains elusive. Because the anterior cingulate cortex (ACC) participates in conflict monitoring and effort-based decision making, and ACC neurons respond to objects in the environment, it may also play a role in the monitoring of moving cues and exerting the appropriate spatial response. We used a robot avoidance task in which a rat had to maintain at least a 25cm distance from a small programmable robot to avoid a foot shock. In successive sessions, we trained ten Long Evans male rats to avoid a fast-moving robot (4cm/s), a stationary robot, and a slow-moving robot (1cm/s). In each condition, the ACC was transiently inactivated by bilateral injections of muscimol in the penultimate session and a control saline injection was given in the last session. Compared to the corresponding saline session, ACC-inactivated rats received more shocks when tested in the fast-moving condition, but not in the stationary or slow robot conditions. Furthermore, ACC-inactivated rats less frequently responded to an approaching robot with appropriate escape responses although their response to shock stimuli remained preserved. Since we observed no effect on slow or stationary robot avoidance, we conclude that the ACC may exert cognitive efforts for monitoring dynamic updating of the position of an object, a role complementary to the dorsal hippocampus.
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Affiliation(s)
- Jan Svoboda
- Department of Neurophysiology of Memory, Institute of Physiology CAS, Prague, Czech Republic.
| | - Veronika Lobellová
- Department of Neurophysiology of Memory, Institute of Physiology CAS, Prague, Czech Republic
| | - Anna Popelíková
- Department of Neurophysiology of Memory, Institute of Physiology CAS, Prague, Czech Republic
| | - Nikhil Ahuja
- Department of Neurophysiology of Memory, Institute of Physiology CAS, Prague, Czech Republic
| | - Eduard Kelemen
- Department of Neurophysiology of Memory, Institute of Physiology CAS, Prague, Czech Republic; National Institute of Mental Health, Klecany, Czech Republic
| | - Aleš Stuchlík
- Department of Neurophysiology of Memory, Institute of Physiology CAS, Prague, Czech Republic.
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Buchtová H, Fajnerová I, Stuchlík A, Kubík Š. Acute systemic MK-801 induced functional uncoupling between hippocampal areas CA3 and CA1 with distant effect in the retrosplenial cortex. Hippocampus 2016; 27:134-144. [DOI: 10.1002/hipo.22678] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/31/2016] [Indexed: 01/24/2023]
Affiliation(s)
- Helena Buchtová
- Laboratory of Neurophysiology of Memory; Institute of Physiology of the Czech Academy of Sciences; Videnska 1083, 14220 Prague 4 Czech Republic
| | - Iveta Fajnerová
- Laboratory of Neurophysiology of Memory; Institute of Physiology of the Czech Academy of Sciences; Videnska 1083, 14220 Prague 4 Czech Republic
| | - Aleš Stuchlík
- Laboratory of Neurophysiology of Memory; Institute of Physiology of the Czech Academy of Sciences; Videnska 1083, 14220 Prague 4 Czech Republic
| | - Štěpán Kubík
- Laboratory of Neurophysiology of Memory; Institute of Physiology of the Czech Academy of Sciences; Videnska 1083, 14220 Prague 4 Czech Republic
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Rolls ET, Kesner RP. Pattern separation and pattern completion in the hippocampal system. Introduction to the Special Issue. Neurobiol Learn Mem 2016; 129:1-3. [PMID: 26872593 DOI: 10.1016/j.nlm.2016.02.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Edmund T Rolls
- Oxford Centre for Computational Neuroscience, Oxford, United Kingdom; University of Warwick, Department of Computer Science, Coventry CV4 7AL, United Kingdom.
| | - Raymond P Kesner
- University of Utah, Department of Psychology, Salt Lake City, UT 84112, USA.
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