1
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Zheng ZS, Huszár R, Hainmueller T, Bartos M, Williams AH, Buzsáki G. Perpetual step-like restructuring of hippocampal circuit dynamics. Cell Rep 2024; 43:114702. [PMID: 39217613 PMCID: PMC11485410 DOI: 10.1016/j.celrep.2024.114702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 06/17/2024] [Accepted: 08/15/2024] [Indexed: 09/04/2024] Open
Abstract
Representation of the environment by hippocampal populations is known to drift even within a familiar environment, which could reflect gradual changes in single-cell activity or result from averaging across discrete switches of single neurons. Disambiguating these possibilities is crucial, as they each imply distinct mechanisms. Leveraging change point detection and model comparison, we find that CA1 population vectors decorrelate gradually within a session. In contrast, individual neurons exhibit predominantly step-like emergence and disappearance of place fields or sustained changes in within-field firing. The changes are not restricted to particular parts of the maze or trials and do not require apparent behavioral changes. The same place fields emerge, disappear, and reappear across days, suggesting that the hippocampus reuses pre-existing assemblies, rather than forming new fields de novo. Our results suggest an internally driven perpetual step-like reorganization of the neuronal assemblies.
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Affiliation(s)
- Zheyang Sam Zheng
- Center for Neural Science, New York University, New York, NY, USA; Neuroscience Institute, NYU Grossman School of Medicine, New York University, New York, NY, USA
| | - Roman Huszár
- Center for Neural Science, New York University, New York, NY, USA; Neuroscience Institute, NYU Grossman School of Medicine, New York University, New York, NY, USA
| | - Thomas Hainmueller
- Department of Psychiatry, NYU Grossman School of Medicine, New York University, New York, NY, USA
| | - Marlene Bartos
- Institute for Physiology I, University of Freiburg Medical Faculty, 79104 Freiburg, Germany
| | - Alex H Williams
- Center for Neural Science, New York University, New York, NY, USA; Neuroscience Institute, NYU Grossman School of Medicine, New York University, New York, NY, USA; Center for Computational Neuroscience, Flatiron Institute, New York, NY, USA.
| | - György Buzsáki
- Neuroscience Institute, NYU Grossman School of Medicine, New York University, New York, NY, USA; Department of Neurology, NYU Grossman School of Medicine, New York University, New York, NY, USA.
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2
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McKenzie S, Sommer AL, Donaldson TN, Pimentel I, Kakani M, Choi IJ, Newman EL, English DF. Event boundaries drive norepinephrine release and distinctive neural representations of space in the rodent hippocampus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.30.605900. [PMID: 39131365 PMCID: PMC11312532 DOI: 10.1101/2024.07.30.605900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 08/13/2024]
Abstract
Episodic memories are temporally segmented around event boundaries that tend to coincide with moments of environmental change. During these times, the state of the brain should change rapidly, or reset, to ensure that the information encountered before and after an event boundary is encoded in different neuronal populations. Norepinephrine (NE) is thought to facilitate this network reorganization. However, it is unknown whether event boundaries drive NE release in the hippocampus and, if so, how NE release relates to changes in hippocampal firing patterns. The advent of the new GRABNE sensor now allows for the measurement of NE binding with sub-second resolution. Using this tool in mice, we tested whether NE is released into the dorsal hippocampus during event boundaries defined by unexpected transitions between spatial contexts and presentations of novel objections. We found that NE binding dynamics were well explained by the time elapsed after each of these environmental changes, and were not related to conditioned behaviors, exploratory bouts of movement, or reward. Familiarity with a spatial context accelerated the rate in which phasic NE binding decayed to baseline. Knowing when NE is elevated, we tested how hippocampal coding of space differs during these moments. Immediately after context transitions we observed relatively unique patterns of neural spiking which settled into a modal state at a similar rate in which NE returned to baseline. These results are consistent with a model wherein NE release drives hippocampal representations away from a steady-state attractor. We hypothesize that the distinctive neural codes observed after each event boundary may facilitate long-term memory and contribute to the neural basis for the primacy effect.
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Affiliation(s)
- Sam McKenzie
- Department of Neurosciences, University of New Mexico Health Science Center, Albuquerque, NM 87106
| | - Alexandra L. Sommer
- Department of Neurosciences, University of New Mexico Health Science Center, Albuquerque, NM 87106
| | - Tia N. Donaldson
- Department of Neurosciences, University of New Mexico Health Science Center, Albuquerque, NM 87106
| | - Infania Pimentel
- Department of Neurosciences, University of New Mexico Health Science Center, Albuquerque, NM 87106
- Department of Mechanical Engineering, Tufts School of Engineering, Medford MA 02155
| | - Meenakshi Kakani
- Department of Neurosciences, University of New Mexico Health Science Center, Albuquerque, NM 87106
- Department of Biology, Virginia Commonwealth University, Richmond, VA 23284
| | - Irene Jungyeon Choi
- Psychological and Brain Sciences, Indiana University, Bloomington, IN, 47405
| | - Ehren L. Newman
- Psychological and Brain Sciences, Indiana University, Bloomington, IN, 47405
- Program in Neuroscience, Indiana University, Bloomington, IN, 47405
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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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Zheng Z(S, Huszár R, Hainmueller T, Bartos M, Williams A, Buzsáki G. Perpetual step-like restructuring of hippocampal circuit dynamics. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.22.590576. [PMID: 38712105 PMCID: PMC11071370 DOI: 10.1101/2024.04.22.590576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Representation of the environment by hippocampal populations is known to drift even within a familiar environment, which could reflect gradual changes in single cell activity or result from averaging across discrete switches of single neurons. Disambiguating these possibilities is crucial, as they each imply distinct mechanisms. Leveraging change point detection and model comparison, we found that CA1 population vectors decorrelated gradually within a session. In contrast, individual neurons exhibited predominantly step-like emergence and disappearance of place fields or sustained change in within-field firing. The changes were not restricted to particular parts of the maze or trials and did not require apparent behavioral changes. The same place fields emerged, disappeared, and reappeared across days, suggesting that the hippocampus reuses pre-existing assemblies, rather than forming new fields de novo. Our results suggest an internally-driven perpetual step-like reorganization of the neuronal assemblies.
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Affiliation(s)
| | - Roman Huszár
- Center for Neural Science, New York University, New York, NY, USA
- Neuroscience Institute, New York University, New York, NY, USA
| | - Thomas Hainmueller
- Department of Psychiatry, NYU Grossman School of Medicine, New York University, New York, NY, USA
| | - Marlene Bartos
- Institute for Physiology I, University of Freiburg, Medical Faculty, 79104 Freiburg, Germany
| | - Alex Williams
- Center for Neural Science, New York University, New York, NY, USA
- Neuroscience Institute, New York University, New York, NY, USA
- Center for Computational Neuroscience, Flatiron Institute
| | - György Buzsáki
- Neuroscience Institute, New York University, New York, NY, USA
- Department of Neurology, and New York University, New York, NY, USA
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5
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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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6
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Fenton AA, Hurtado JR, Broek JAC, Park E, Mishra B. Do Place Cells Dream of Deceptive Moves in a Signaling Game? Neuroscience 2023; 529:129-147. [PMID: 37591330 PMCID: PMC10592151 DOI: 10.1016/j.neuroscience.2023.08.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 07/27/2023] [Accepted: 08/06/2023] [Indexed: 08/19/2023]
Abstract
We consider the possibility of applying game theory to analysis and modeling of neurobiological systems. Specifically, the basic properties and features of information asymmetric signaling games are considered and discussed as having potential to explain diverse neurobiological phenomena; we focus on neuronal action potential discharge that can represent cognitive variables in memory and purposeful behavior. We begin by arguing that there is a pressing need for conceptual frameworks that can permit analysis and integration of information and explanations across many scales of biological function including gene regulation, molecular and biochemical signaling, cellular and metabolic function, neuronal population, and systems level organization to generate plausible hypotheses across these scales. Developing such integrative frameworks is crucial if we are to understand cognitive functions like learning, memory, and perception. The present work focuses on systems neuroscience organized around the connected brain regions of the entorhinal cortex and hippocampus. These areas are intensely studied in rodent subjects as model neuronal systems that undergo activity-dependent synaptic plasticity to form neuronal circuits and represent memories and spatial knowledge used for purposeful navigation. Examples of cognition-related spatial information in the observed neuronal discharge of hippocampal place cell populations and medial entorhinal head-direction cell populations are used to illustrate possible challenges to information maximization concepts. It may be natural to explain these observations using the ideas and features of information asymmetric signaling games.
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Affiliation(s)
- André A Fenton
- Neurobiology of Cognition Laboratory, Center for Neural Science, New York University, New York, NY, USA; Neuroscience Institute at the NYU Langone Medical Center, New York, NY, USA.
| | - José R Hurtado
- Neurobiology of Cognition Laboratory, Center for Neural Science, New York University, New York, NY, USA
| | - Jantine A C Broek
- Departments of Computer Science and Mathematics, Courant Institute of Mathematical Sciences, New York University, New York, NY, USA
| | - EunHye Park
- Neurobiology of Cognition Laboratory, Center for Neural Science, New York University, New York, NY, USA
| | - Bud Mishra
- Departments of Computer Science and Mathematics, Courant Institute of Mathematical Sciences, New York University, New York, NY, USA; Department of Cell Biology, NYU Langone Medical Center, New York, NY, USA; Simon Center for Quantitative Biology, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
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7
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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: 13] [Impact Index Per Article: 13.0] [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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8
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Billig AJ, Lad M, Sedley W, Griffiths TD. The hearing hippocampus. Prog Neurobiol 2022; 218:102326. [PMID: 35870677 PMCID: PMC10510040 DOI: 10.1016/j.pneurobio.2022.102326] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 06/08/2022] [Accepted: 07/18/2022] [Indexed: 11/17/2022]
Abstract
The hippocampus has a well-established role in spatial and episodic memory but a broader function has been proposed including aspects of perception and relational processing. Neural bases of sound analysis have been described in the pathway to auditory cortex, but wider networks supporting auditory cognition are still being established. We review what is known about the role of the hippocampus in processing auditory information, and how the hippocampus itself is shaped by sound. In examining imaging, recording, and lesion studies in species from rodents to humans, we uncover a hierarchy of hippocampal responses to sound including during passive exposure, active listening, and the learning of associations between sounds and other stimuli. We describe how the hippocampus' connectivity and computational architecture allow it to track and manipulate auditory information - whether in the form of speech, music, or environmental, emotional, or phantom sounds. Functional and structural correlates of auditory experience are also identified. The extent of auditory-hippocampal interactions is consistent with the view that the hippocampus makes broad contributions to perception and cognition, beyond spatial and episodic memory. More deeply understanding these interactions may unlock applications including entraining hippocampal rhythms to support cognition, and intervening in links between hearing loss and dementia.
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Affiliation(s)
| | - Meher Lad
- Translational and Clinical Research Institute, Newcastle University Medical School, Newcastle upon Tyne, UK
| | - William Sedley
- Translational and Clinical Research Institute, Newcastle University Medical School, Newcastle upon Tyne, UK
| | - Timothy D Griffiths
- Biosciences Institute, Newcastle University Medical School, Newcastle upon Tyne, UK; Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, London, UK; Human Brain Research Laboratory, Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, USA
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9
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Kumar MG, Tan C, Libedinsky C, Yen SC, Tan AYY. A Nonlinear Hidden Layer Enables Actor-Critic Agents to Learn Multiple Paired Association Navigation. Cereb Cortex 2022; 32:3917-3936. [PMID: 35034127 DOI: 10.1093/cercor/bhab456] [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: 07/23/2021] [Revised: 11/05/2021] [Accepted: 11/06/2021] [Indexed: 11/15/2022] Open
Abstract
Navigation to multiple cued reward locations has been increasingly used to study rodent learning. Though deep reinforcement learning agents have been shown to be able to learn the task, they are not biologically plausible. Biologically plausible classic actor-critic agents have been shown to learn to navigate to single reward locations, but which biologically plausible agents are able to learn multiple cue-reward location tasks has remained unclear. In this computational study, we show versions of classic agents that learn to navigate to a single reward location, and adapt to reward location displacement, but are not able to learn multiple paired association navigation. The limitation is overcome by an agent in which place cell and cue information are first processed by a feedforward nonlinear hidden layer with synapses to the actor and critic subject to temporal difference error-modulated plasticity. Faster learning is obtained when the feedforward layer is replaced by a recurrent reservoir network.
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Affiliation(s)
- M Ganesh Kumar
- Integrative Sciences and Engineering Programme, NUS Graduate School, National University of Singapore, Singapore 119077, Singapore
- The N.1 Institute for Health, National University of Singapore, Singapore 117456, Singapore
- Innovation and Design Programme, Faculty of Engineering, National University of Singapore, Singapore 117579, Singapore
| | - Cheston Tan
- Institute for Infocomm Research, Agency for Science, Technology and Research, Singapore 138632, Singapore
| | - Camilo Libedinsky
- Integrative Sciences and Engineering Programme, NUS Graduate School, National University of Singapore, Singapore 119077, Singapore
- The N.1 Institute for Health, National University of Singapore, Singapore 117456, Singapore
- Department of Psychology, National University of Singapore, Singapore 117570, Singapore
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore 138673, Singapore
| | - Shih-Cheng Yen
- Integrative Sciences and Engineering Programme, NUS Graduate School, National University of Singapore, Singapore 119077, Singapore
- The N.1 Institute for Health, National University of Singapore, Singapore 117456, Singapore
- Innovation and Design Programme, Faculty of Engineering, National University of Singapore, Singapore 117579, Singapore
| | - Andrew Y Y Tan
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117593, Singapore
- Healthy Longevity Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
- Cardiovascular Disease Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
- Neurobiology Programme, Life Sciences Institute, National University of Singapore, Singapore 119077, Singapore
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10
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Abstract
By linking the past with the future, our memories define our sense of identity. Because human memory engages the conscious realm, its examination has historically been approached from language and introspection and proceeded largely along separate parallel paths in humans and other animals. Here, we first highlight the achievements and limitations of this mind-based approach and make the case for a new brain-based understanding of declarative memory with a focus on hippocampal physiology. Next, we discuss the interleaved nature and common physiological mechanisms of navigation in real and mental spacetime. We suggest that a distinguishing feature of memory types is whether they subserve actions for single or multiple uses. Finally, in contrast to the persisting view of the mind as a highly plastic blank slate ready for the world to make its imprint, we hypothesize that neuronal networks are endowed with a reservoir of neural trajectories, and the challenge faced by the brain is how to select and match preexisting neuronal trajectories with events in the world.
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Affiliation(s)
- György Buzsáki
- Neuroscience Institute and Department of Neurology, NYU Grossman School of Medicine, New York University, New York, NY 10016, USA;
- Center for Neural Science, New York University, New York, NY 10003, USA
| | - Sam McKenzie
- Department of Neurosciences, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - Lila Davachi
- Department of Psychology, Columbia University, New York, NY 10027, USA
- Center for Biomedical Imaging and Neuromodulation, Nathan S. Kline Institute for Psychiatric Research, Orangeburg, New York 10962, USA
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11
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Wikenheiser AM, Gardner MPH, Mueller LE, Schoenbaum G. Spatial Representations in Rat Orbitofrontal Cortex. J Neurosci 2021; 41:6933-6945. [PMID: 34210776 PMCID: PMC8360685 DOI: 10.1523/jneurosci.0830-21.2021] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Revised: 06/09/2021] [Accepted: 06/20/2021] [Indexed: 01/03/2023] Open
Abstract
The orbitofrontal cortex (OFC) and hippocampus share striking cognitive and functional similarities. As a result, both structures have been proposed to encode "cognitive maps" that provide useful scaffolds for planning complex behaviors. However, while this function has been exemplified by spatial coding in neurons of hippocampal regions-particularly place and grid cells-spatial representations in the OFC have been investigated far less. Here we sought to address this by recording OFC neurons from male rats engaged in an open-field foraging task like that originally developed to characterize place fields in rodent hippocampal neurons. Single-unit activity was recorded as rats searched for food pellets scattered randomly throughout a large enclosure. In some sessions, particular flavors of food occurred more frequently in particular parts of the enclosure; in others, only a single flavor was used. OFC neurons showed spatially localized firing fields in both conditions, and representations changed between flavored and unflavored foraging periods in a manner reminiscent of remapping in the hippocampus. Compared with hippocampal recordings taken under similar behavioral conditions, OFC spatial representations were less temporally reliable, and there was no significant evidence of grid tuning in OFC neurons. These data confirm that OFC neurons show spatial firing fields in a large, two-dimensional environment in a manner similar to hippocampus. Consistent with the focus of the OFC on biological meaning and goals, spatial coding was weaker than in hippocampus and influenced by outcome identity.SIGNIFICANCE STATEMENT The orbitofrontal cortex (OFC) and hippocampus have both been proposed to encode "cognitive maps" that provide useful scaffolds for planning complex behaviors. This function is exemplified by place and grid cells identified in hippocampus, the activity of which maps spatial environments. The current study directly demonstrates very similar, though not identical, spatial representatives in OFC neurons, confirming that OFC-like hippocampus-can represent a spatial map under the appropriate experimental conditions.
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Affiliation(s)
- Andrew M Wikenheiser
- Department of Psychology, University of California, Los Angeles, Los Angeles, California 90095
- Brain Research Institute, University of California, Los Angeles, Los Angeles, California 90095
| | - Matthew P H Gardner
- Behavioral Neurophysiology Research Section, Cellular Neurobiology Research Branch, Intramural Research Program, National Institute on Drug Abuse, Baltimore, Maryland 21224
| | - Lauren E Mueller
- Behavioral Neurophysiology Research Section, Cellular Neurobiology Research Branch, Intramural Research Program, National Institute on Drug Abuse, Baltimore, Maryland 21224
| | - Geoffrey Schoenbaum
- Behavioral Neurophysiology Research Section, Cellular Neurobiology Research Branch, Intramural Research Program, National Institute on Drug Abuse, Baltimore, Maryland 21224
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12
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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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13
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McKenzie S, Huszár R, English DF, Kim K, Christensen F, Yoon E, Buzsáki G. Preexisting hippocampal network dynamics constrain optogenetically induced place fields. Neuron 2021; 109:1040-1054.e7. [PMID: 33539763 PMCID: PMC8095399 DOI: 10.1016/j.neuron.2021.01.011] [Citation(s) in RCA: 60] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 10/19/2020] [Accepted: 01/11/2021] [Indexed: 02/06/2023]
Abstract
Memory models often emphasize the need to encode novel patterns of neural activity imposed by sensory drive. Prior learning and innate architecture likely restrict neural plasticity, however. Here, we test how the incorporation of synthetic hippocampal signals is constrained by preexisting circuit dynamics. We optogenetically stimulated small groups of CA1 neurons as mice traversed a chosen segment of a linear track, mimicking the emergence of place fields. Stimulation induced persistent place field remapping in stimulated and non-stimulated neurons. The emergence of place fields could be predicted from sporadic firing in the new place field location and the temporal relationship to peer neurons before the optogenetic perturbation. Circuit modification was reflected by altered spike transmission between connected pyramidal cells and inhibitory interneurons, which persisted during post-experience sleep. We hypothesize that optogenetic perturbation unmasked sub-threshold place fields. Plasticity in recurrent/lateral inhibition may drive learning through the rapid association of existing states.
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Affiliation(s)
- Sam McKenzie
- The Neuroscience Institute, Department of Neurology, NYU Langone Medical Center and Center for Neural Science, New York, NY 10016, USA; Department of Neurosciences, University of New Mexico, Albuquerque, NM 87131, USA
| | - Roman Huszár
- The Neuroscience Institute, Department of Neurology, NYU Langone Medical Center and Center for Neural Science, New York, NY 10016, USA; Center for Neural Science, New York University, 4 Washington Place, New York, NY 10003, USA
| | - Daniel F English
- The Neuroscience Institute, Department of Neurology, NYU Langone Medical Center and Center for Neural Science, New York, NY 10016, USA; School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - Kanghwan Kim
- Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI 48109, USA
| | - Fletcher Christensen
- Department of Mathematics and Statistics, The University of New Mexico, Albuquerque, NM 87131, USA
| | - Euisik Yoon
- Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI 48109, USA; Center for Nanomedicine, Institute for Basic Science (IBS) and Graduate Program of Nano Biomedical Engineering (Nano BME), Yonsei University, Seoul 03722, Republic of Korea
| | - György Buzsáki
- The Neuroscience Institute, Department of Neurology, NYU Langone Medical Center and Center for Neural Science, New York, NY 10016, USA; Center for Neural Science, New York University, 4 Washington Place, New York, NY 10003, USA.
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14
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Dabaghian Y. From Topological Analyses to Functional Modeling: The Case of Hippocampus. Front Comput Neurosci 2021; 14:593166. [PMID: 33505262 PMCID: PMC7829363 DOI: 10.3389/fncom.2020.593166] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Accepted: 12/02/2020] [Indexed: 11/13/2022] Open
Abstract
Topological data analyses are widely used for describing and conceptualizing large volumes of neurobiological data, e.g., for quantifying spiking outputs of large neuronal ensembles and thus understanding the functions of the corresponding networks. Below we discuss an approach in which convergent topological analyses produce insights into how information may be processed in mammalian hippocampus—a brain part that plays a key role in learning and memory. The resulting functional model provides a unifying framework for integrating spiking data at different timescales and following the course of spatial learning at different levels of spatiotemporal granularity. This approach allows accounting for contributions from various physiological phenomena into spatial cognition—the neuronal spiking statistics, the effects of spiking synchronization by different brain waves, the roles played by synaptic efficacies and so forth. In particular, it is possible to demonstrate that networks with plastic and transient synaptic architectures can encode stable cognitive maps, revealing the characteristic timescales of memory processing.
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Affiliation(s)
- Yuri Dabaghian
- Department of Neurology, The University of Texas McGovern Medical School, Houston, TX, United States
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15
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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: 55] [Impact Index Per Article: 13.8] [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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16
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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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17
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van der Meer MAA, Kemere C, Diba K. Progress and issues in second-order analysis of hippocampal replay. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190238. [PMID: 32248780 DOI: 10.1098/rstb.2019.0238] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Patterns of neural activity that occur spontaneously during sharp-wave ripple (SWR) events in the hippocampus are thought to play an important role in memory formation, consolidation and retrieval. Typical studies examining the content of SWRs seek to determine whether the identity and/or temporal order of cell firing is different from chance. Such 'first-order' analyses are focused on a single time point and template (map), and have been used to show, for instance, the existence of preplay. The major methodological challenge in first-order analyses is the construction and interpretation of different chance distributions. By contrast, 'second-order' analyses involve a comparison of SWR content between different time points, and/or between different templates. Typical second-order questions include tests of experience-dependence (replay) that compare SWR content before and after experience, and comparisons or replay between different arms of a maze. Such questions entail additional methodological challenges that can lead to biases in results and associated interpretations. We provide an inventory of analysis challenges for second-order questions about SWR content, and suggest ways of preventing, identifying and addressing possible analysis biases. Given evolving interest in understanding SWR content in more complex experimental scenarios and across different time scales, we expect these issues to become increasingly pervasive. This article is part of the Theo Murphy meeting issue 'Memory reactivation: replaying events past, present and future'.
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Affiliation(s)
| | - Caleb Kemere
- Department of Electrical and Computer Engineering, Rice University, Houston, TX, USA
| | - Kamran Diba
- Neuroscience Graduate Program, University of Michigan Medical School, Ann Arbor, MI 48109, USA.,Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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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: 38] [Impact Index Per Article: 9.5] [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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The hippocampal sharp wave-ripple in memory retrieval for immediate use and consolidation. Nat Rev Neurosci 2019; 19:744-757. [PMID: 30356103 DOI: 10.1038/s41583-018-0077-1] [Citation(s) in RCA: 229] [Impact Index Per Article: 45.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Various cognitive functions have long been known to require the hippocampus. Recently, progress has been made in identifying the hippocampal neural activity patterns that implement these functions. One such pattern is the sharp wave-ripple (SWR), an event associated with highly synchronous neural firing in the hippocampus and modulation of neural activity in distributed brain regions. Hippocampal spiking during SWRs can represent past or potential future experience, and SWR-related interventions can alter subsequent memory performance. These findings and others suggest that SWRs support both memory consolidation and memory retrieval for processes such as decision-making. In addition, studies have identified distinct types of SWR based on representational content, behavioural state and physiological features. These various findings regarding SWRs suggest that different SWR types correspond to different cognitive functions, such as retrieval and consolidation. Here, we introduce another possibility - that a single SWR may support more than one cognitive function. Taking into account classic psychological theories and recent molecular results that suggest that retrieval and consolidation share mechanisms, we propose that the SWR mediates the retrieval of stored representations that can be utilized immediately by downstream circuits in decision-making, planning, recollection and/or imagination while simultaneously initiating memory consolidation processes.
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21
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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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22
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Aoki Y, Igata H, Ikegaya Y, Sasaki T. The Integration of Goal-Directed Signals onto Spatial Maps of Hippocampal Place Cells. Cell Rep 2019; 27:1516-1527.e5. [DOI: 10.1016/j.celrep.2019.04.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 02/17/2019] [Accepted: 03/27/2019] [Indexed: 12/23/2022] Open
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23
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Dabaghian Y. Through synapses to spatial memory maps via a topological model. Sci Rep 2019; 9:572. [PMID: 30679520 PMCID: PMC6345962 DOI: 10.1038/s41598-018-36807-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 11/22/2018] [Indexed: 12/16/2022] Open
Abstract
Various neurophysiological and cognitive functions are based on transferring information between spiking neurons via a complex system of synaptic connections. In particular, the capacity of presynaptic inputs to influence the postsynaptic outputs–the efficacy of the synapses–plays a principal role in all aspects of hippocampal neurophysiology. However, a direct link between the information processed at the level of individual synapses and the animal’s ability to form memories at the organismal level has not yet been fully understood. Here, we investigate the effect of synaptic transmission probabilities on the ability of the hippocampal place cell ensembles to produce a cognitive map of the environment. Using methods from algebraic topology, we find that weakening synaptic connections increase spatial learning times, produce topological defects in the large-scale representation of the ambient space and restrict the range of parameters for which place cell ensembles are capable of producing a map with correct topological structure. On the other hand, the results indicate a possibility of compensatory phenomena, namely that spatial learning deficiencies may be mitigated through enhancement of neuronal activity.
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Affiliation(s)
- Yuri Dabaghian
- Department of Neurology, The University of Texas McGovern Medical School, 6431 Fannin St, Houston, TX, 77030, USA.
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24
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Ramirez-Villegas JF, Willeke KF, Logothetis NK, Besserve M. Dissecting the Synapse- and Frequency-Dependent Network Mechanisms of In Vivo Hippocampal Sharp Wave-Ripples. Neuron 2018; 100:1224-1240.e13. [DOI: 10.1016/j.neuron.2018.09.041] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 06/25/2018] [Accepted: 09/24/2018] [Indexed: 01/14/2023]
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25
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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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26
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Wohlgemuth MJ, Yu C, Moss CF. 3D Hippocampal Place Field Dynamics in Free-Flying Echolocating Bats. Front Cell Neurosci 2018; 12:270. [PMID: 30190673 PMCID: PMC6115611 DOI: 10.3389/fncel.2018.00270] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 08/02/2018] [Indexed: 12/20/2022] Open
Abstract
A large body of laboratory research has investigated the process by which environmental cues are acquired and used for spatial navigation in rodents; however, the key to differentiating between species specializations and general principles lies in comparative research. Rodent research has focused on a class of neurons in the hippocampus implicated in the representation of allocentric space - termed place cells - and the process by which these representations form. One class of models of hippocampal place field formation depends on continuous theta, a low frequency brain oscillation that is prevalent in crawling rodents. Comparative studies of hippocampal activity in echolocating bats have reported many findings that parallel the rodent literature, but also describe noteworthy species differences, especially with respect to theta rhythm. Here, we first discuss studies of the bat hippocampal formation and point to gaps in our knowledge, which motivate our new lines of inquiry. We present data from the free-flying laryngeal echolocating big brown bat, which shows 3-D place cells without continuous theta, similar to reports from the lingual echolocating Egyptian fruit bat. We also report findings, which demonstrate that the animal's control over echolocation call rate (sensory sampling) influences place field tuning. These results motivate future comparative research on hippocampal function in the context of natural sensory-guided behaviors.
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Affiliation(s)
- Melville J. Wohlgemuth
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, United States
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27
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The cognitive nuances of surprising events: exposure to unexpected stimuli elicits firing variations in neurons of the dorsal CA1 hippocampus. Brain Struct Funct 2018; 223:3183-3211. [PMID: 29789932 PMCID: PMC6132666 DOI: 10.1007/s00429-018-1681-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2017] [Accepted: 05/08/2018] [Indexed: 12/02/2022]
Abstract
The ability to recognize novel situations is among the most fascinating and vital of the brain functions. A hypothesis posits that encoding of novelty is prompted by failures in expectancy, according to computation matching incoming information with stored events. Thus, unexpected changes in context are detected within the hippocampus and transferred to downstream structures, eliciting the arousal of the dopamine system. Nevertheless, the precise locus of detection is a matter of debate. The dorsal CA1 hippocampus (dCA1) appears as an ideal candidate for operating a mismatch computation and discriminating the occurrence of diverse stimuli within the same environment. In this study, we sought to determine dCA1 neuronal firing during the experience of novel stimuli embedded in familiar contexts. We performed population recordings while head-fixed mice navigated virtual environments. Three stimuli were employed, namely a novel pattern of visual cues, an odor, and a reward with enhanced valence. The encounter of unexpected events elicited profound variations in dCA1 that were assessed both as opposite rate directions and altered network connectivity. When experienced in sequence, novel stimuli elicited specific responses that often exhibited cross-sensitization. Short-latency, event-triggered responses were in accordance with the detection of novelty being computed within dCA1. We postulate that firing variations trigger neuronal disinhibition, and constitute a fundamental mechanism in the processing of unexpected events and in learning. Elucidating the mechanisms underlying detection and computation of novelty might help in understanding hippocampal-dependent cognitive dysfunctions associated with neuropathologies and psychiatric conditions.
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28
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On How the Dentate Gyrus Contributes to Memory Discrimination. Neuron 2018; 98:832-845.e5. [PMID: 29731252 DOI: 10.1016/j.neuron.2018.04.018] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 02/13/2018] [Accepted: 04/16/2018] [Indexed: 11/20/2022]
Abstract
The dentate gyrus (DG) is crucial for behaviorally discriminating similar spatial memories, predicting that DG place cells change ("remap") their relative spatial tuning ("place fields") for memory discrimination. This prediction was never tested, although DG place cells remap across similar environments without memory tasks. We confirm this prior finding but find that DG place fields do not remap across spatial tasks that require DG-dependent memory discrimination. Instead of remapping, place-discriminating discharge is observed transiently among DG place cells, particularly when memory discrimination is most necessary. The DG network may signal memory discrimination by expressing distinctive sub-second network patterns of co-firing at memory discrimination sites. This involves increased coupling of discharge from place cells and interneurons, as was observed during successful, but not failed, behavioral expression of memory discrimination. Instead of remapping, these findings indicate that memory discrimination is signaled by sub-second patterns of correlated discharge within the dentate network.
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29
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Yagi S, Igata H, Shikano Y, Aoki Y, Sasaki T, Ikegaya Y. Time-varying synchronous cell ensembles during consummatory periods correlate with variable numbers of place cell spikes. Hippocampus 2018; 28:471-483. [DOI: 10.1002/hipo.22846] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 02/20/2018] [Accepted: 03/25/2018] [Indexed: 11/09/2022]
Affiliation(s)
- Saichiro Yagi
- Graduate School of Pharmaceutical Sciences; University of Tokyo, 7-3-1 Hongo Bunkyo-ku; Tokyo, 113-0033 Japan
| | - Hideyoshi Igata
- Graduate School of Pharmaceutical Sciences; University of Tokyo, 7-3-1 Hongo Bunkyo-ku; Tokyo, 113-0033 Japan
| | - Yu Shikano
- Graduate School of Pharmaceutical Sciences; University of Tokyo, 7-3-1 Hongo Bunkyo-ku; Tokyo, 113-0033 Japan
| | - Yuki Aoki
- Graduate School of Pharmaceutical Sciences; University of Tokyo, 7-3-1 Hongo Bunkyo-ku; Tokyo, 113-0033 Japan
| | - Takuya Sasaki
- Graduate School of Pharmaceutical Sciences; University of Tokyo, 7-3-1 Hongo Bunkyo-ku; Tokyo, 113-0033 Japan
| | - Yuji Ikegaya
- Graduate School of Pharmaceutical Sciences; University of Tokyo, 7-3-1 Hongo Bunkyo-ku; Tokyo, 113-0033 Japan
- Center for Information and Neural Networks; Suita City Osaka, 565-0871 Japan
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30
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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: 39] [Impact Index Per Article: 6.5] [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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Cholvin T, Hok V, Giorgi L, Chaillan FA, Poucet B. Ventral Midline Thalamus Is Necessary for Hippocampal Place Field Stability and Cell Firing Modulation. J Neurosci 2018; 38:158-172. [PMID: 29133436 PMCID: PMC6705806 DOI: 10.1523/jneurosci.2039-17.2017] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 10/12/2017] [Accepted: 11/07/2017] [Indexed: 12/21/2022] Open
Abstract
The reuniens (Re) and rhomboid (Rh) nuclei of the ventral midline thalamus are reciprocally connected with the hippocampus (Hip) and the medial prefrontal cortex (mPFC). Growing evidence suggests that these nuclei might play a crucial role in cognitive processes requiring Hip-mPFC interactions, including spatial navigation. Here, we tested the effect of ReRh lesions on the firing properties and spatial activity of dorsal hippocampal CA1 place cells as male rats explored a familiar or a novel environment. We found no change in the spatial characteristics of CA1 place cells in the familiar environment following ReRh lesions. Contrariwise, spatial coherence was decreased during the first session in a novel environment. We then investigated field stability of place cells recorded across 5 d both in the familiar and in a novel environment presented in a predefined sequence. While the remapping capacity of the place cells was not affected by the lesion, our results clearly demonstrated a disruption of the CA1 cellular representation of both environments in ReRh rats. More specifically, we found ReRh lesions to produce (1) a pronounced and long-lasting decrease of place field stability and (2) a strong alteration of overdispersion (i.e., firing variability). Thus, in ReRh rats, exploration of a novel environment appears to interfere with the representation of the familiar one, leading to decreased field stability in both environments. The present study shows the involvement of ReRh nuclei in the long-term spatial stability of CA1 place fields.SIGNIFICANCE STATEMENT Growing evidence suggest that the ventral midline thalamic nuclei (reuniens and rhomboid) might play a substantial role in various cognitive tasks including spatial memory. In the present article, we show that the lesions of these nuclei impair the spatial representations encoded by CA1 place cells of both familiar and novel environments. First, reduced variability of place cell firing appears to indicate an impairment of attentional processes. Second, impaired stability of place cell representations could explain the long-term memory deficits observed in previous behavioral studies.
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Affiliation(s)
- Thibault Cholvin
- Laboratoire de Neurosciences Cognitives and
- Federation 3C, CNRS, Aix Marseille University, 13331 Marseille, France
| | - Vincent Hok
- Laboratoire de Neurosciences Cognitives and
- Federation 3C, CNRS, Aix Marseille University, 13331 Marseille, France
| | - Lisa Giorgi
- Laboratoire de Neurosciences Cognitives and
- Federation 3C, CNRS, Aix Marseille University, 13331 Marseille, France
| | - Franck A Chaillan
- Laboratoire de Neurosciences Cognitives and
- Federation 3C, CNRS, Aix Marseille University, 13331 Marseille, France
| | - Bruno Poucet
- Laboratoire de Neurosciences Cognitives and
- Federation 3C, CNRS, Aix Marseille University, 13331 Marseille, France
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Tanila H, Ku S, Kloosterman F, Wilson MA. Characteristics of CA1 place fields in a complex maze with multiple choice points. Hippocampus 2017; 28:81-96. [PMID: 29072798 DOI: 10.1002/hipo.22810] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 10/21/2017] [Accepted: 10/24/2017] [Indexed: 11/06/2022]
Abstract
For the sake of rigorous control of task variables, hippocampal place cells have been usually studied in relatively simple environments. To approach the situation of real-life navigation in an urban-like environment, we recorded CA1 place cells while rats performance a memory task in a "Townmaze" with two start locations, three alternate paths in the maze midsection, followed by a two-way choice that determined the trial outcome, access to a goal compartment. Further, to test the ability of place cells to update their spatial representation upon local changes in the environment while maintaining the integrity of the overall spatial map to allow effective navigation, we occasionally introduced barriers in the maze mid-section to force the rat to select a nonpreferred route. The "Townmaze" revealed many new interesting features of CA1 neurons. First, we found neurons with 3-5 fields that appear to represent segments on a single common route through the maze. Second, we found neurons with 3-5 fields similarly aligned along the longitudinal or transverse maze axis. Responses to the barriers were assessed separately near and far from the barriers. Appearance of new fields in response to the barriers took place almost exclusively only locally near the barrier, whereas in-field firing rate changes occurred throughout the maze. Further, field location changes did not correlate with the task performance, whereas firing rate changes did. These findings suggest that in a complex environment with blocked distal views, CA1 neurons code for the environment as sequences of significant nodes but are also capable of extracting and associating common elements across these sequences.
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Affiliation(s)
- H Tanila
- A. I. Virtanen Institute, University of Eastern Finland, Kuopio, Finland
| | - S Ku
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - F Kloosterman
- Neuro-Electronics Research Flanders, Leuven, Belgium.,Imec, Leuven, Belgium.,Biological Psychology, KU Leuven, Leuven, Belgium
| | - M A Wilson
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts
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35
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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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36
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Newman EL, Venditto SJC, Climer JR, Petter EA, Gillet SN, Levy S. Precise spike timing dynamics of hippocampal place cell activity sensitive to cholinergic disruption. Hippocampus 2017. [PMID: 28628945 PMCID: PMC5638075 DOI: 10.1002/hipo.22753] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
New memory formation depends on both the hippocampus and modulatory effects of acetylcholine. The mechanism by which acetylcholine levels in the hippocampus enable new encoding remains poorly understood. Here, we tested the hypothesis that cholinergic modulation supports memory formation by leading to structured spike timing in the hippocampus. Specifically, we tested if phase precession in dorsal CA1 was reduced under the influence of a systemic cholinergic antagonist. Unit and field potential were recorded from the dorsal CA1 of rats as they completed laps on a circular track for food rewards before and during the influence of the systemically administered acetylcholine muscarinic receptor antagonist scopolamine. We found that scopolamine significantly reduced phase precession of spiking relative to the field theta, and that this was due to a decrease in the frequency of the spiking rhythmicity. We also found that the correlation between position and theta phase was significantly reduced. This effect was not due to changes in spatial tuning as tuning remained stable for those cells analyzed. Similarly, it was not due to changes in lap‐to‐lap reliability of spiking onset or offset relative to either position or phase as the reliability did not decrease following scopolamine administration. These findings support the hypothesis that memory impairments that follow muscarinic blockade are the result of degraded spike timing in the hippocampus.
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Affiliation(s)
- Ehren L Newman
- Department of Psychological and Brain Sciences, 1101 E 10th St, Bloomington, Indiana, 47405
| | - Sarah Jo C Venditto
- Department of Psychological and Brain Sciences, 1101 E 10th St, Bloomington, Indiana, 47405
| | - Jason R Climer
- Center for Memory and Brain, Department of Psychology, Boston University, 2 Cummington Mall, Boston, Massachusetts, 02215.,Department of Neurobiology, Northwestern University, Hogan 2-160 2205 Tech Drive Evanston, IL, 60208
| | - Elijah A Petter
- Department of Psychology and Neuroscience, Duke University, 417 Chapel Drive Campus Box 90086 Duke University Durham, NC, 27708
| | - Shea N Gillet
- Center for Neural Circuits and Behavior and Department of Neurosciences, University of California, San Diego, La Jolla, CA, 92093
| | - Sam Levy
- Center for Memory and Brain, Department of Psychology, Boston University, 2 Cummington Mall, Boston, Massachusetts, 02215
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37
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Mark S, Romani S, Jezek K, Tsodyks M. Theta-paced flickering between place-cell maps in the hippocampus: A model based on short-term synaptic plasticity. Hippocampus 2017; 27:959-970. [PMID: 28558154 PMCID: PMC5575492 DOI: 10.1002/hipo.22743] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 05/16/2017] [Accepted: 05/18/2017] [Indexed: 01/29/2023]
Abstract
Hippocampal place cells represent different environments with distinct neural activity patterns. Following an abrupt switch between two familiar configurations of visual cues defining two environments, the hippocampal neural activity pattern switches almost immediately to the corresponding representation. Surprisingly, during a transient period following the switch to the new environment, occasional fast transitions between the two activity patterns (flickering) were observed (Jezek, Henriksen, Treves, Moser, & Moser, 2011). Here we show that an attractor neural network model of place cells with connections endowed with short‐term synaptic plasticity can account for this phenomenon. A memory trace of the recent history of network activity is maintained in the state of the synapses, allowing the network to temporarily reactivate the representation of the previous environment in the absence of the corresponding sensory cues. The model predicts that the number of flickering events depends on the amplitude of the ongoing theta rhythm and the distance between the current position of the animal and its position at the time of cue switching. We test these predictions with new analysis of experimental data. These results suggest a potential role of short‐term synaptic plasticity in recruiting the activity of different cell assemblies and in shaping hippocampal activity of behaving animals.
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Affiliation(s)
- Shirley Mark
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Sandro Romani
- HHMI Janelia Research Campus, Ashburn, Virginia, 20147, USA
| | - Karel Jezek
- Biomedical Center, Faculty of Medicine in Pilsen, Charles University, Pilsen, 32300, Czech Republic.,Kavli Institute for Systems Neuroscience and Centre for Neural Computation, Norwegian University of Science and Technology, Trondheim, 7491, Norway
| | - Misha Tsodyks
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, 76100, Israel
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38
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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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39
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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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40
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Hippocampal Offline Reactivation Consolidates Recently Formed Cell Assembly Patterns during Sharp Wave-Ripples. Neuron 2016; 92:968-974. [PMID: 27840002 PMCID: PMC5158132 DOI: 10.1016/j.neuron.2016.10.020] [Citation(s) in RCA: 170] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 08/16/2016] [Accepted: 09/21/2016] [Indexed: 12/15/2022]
Abstract
The ability to reinstate neuronal assemblies representing mnemonic information is thought to require their consolidation through offline reactivation during sleep/rest. To test this, we detected cell assembly patterns formed by repeated neuronal co-activations in the mouse hippocampus during exploration of spatial environments. We found that the reinstatement of assembly patterns representing a novel, but not a familiar, environment correlated with their offline reactivation and was impaired by closed-loop optogenetic disruption of sharp wave-ripple oscillations. Moreover, we discovered that reactivation was only required for the reinstatement of assembly patterns whose expression was gradually strengthened during encoding of a novel place. The context-dependent reinstatement of assembly patterns whose expression did not gain in strength beyond the first few minutes of spatial encoding was not dependent on reactivation. This demonstrates that the hippocampus can hold concurrent representations of space that markedly differ in their encoding dynamics and their dependence on offline reactivation for consolidation. Video Abstract
Multi-neuron co-activations form space-coding assembly patterns in the hippocampus Offline reactivation of new assembly patterns correlates with future reinstatement SWR silencing impairs consolidation of patterns of a novel, but not a familiar, place “Early stabilized” patterns representing a novel place do not require reactivation
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41
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Kelemen E, Fenton AA. Coordinating different representations in the hippocampus. Neurobiol Learn Mem 2016; 129:50-9. [DOI: 10.1016/j.nlm.2015.12.011] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Revised: 12/23/2015] [Accepted: 12/25/2015] [Indexed: 01/14/2023]
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42
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Attention promotes episodic encoding by stabilizing hippocampal representations. Proc Natl Acad Sci U S A 2016; 113:E420-9. [PMID: 26755611 DOI: 10.1073/pnas.1518931113] [Citation(s) in RCA: 110] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Attention influences what is later remembered, but little is known about how this occurs in the brain. We hypothesized that behavioral goals modulate the attentional state of the hippocampus to prioritize goal-relevant aspects of experience for encoding. Participants viewed rooms with paintings, attending to room layouts or painting styles on different trials during high-resolution functional MRI. We identified template activity patterns in each hippocampal subfield that corresponded to the attentional state induced by each task. Participants then incidentally encoded new rooms with art while attending to the layout or painting style, and memory was subsequently tested. We found that when task-relevant information was better remembered, the hippocampus was more likely to have been in the correct attentional state during encoding. This effect was specific to the hippocampus, and not found in medial temporal lobe cortex, category-selective areas of the visual system, or elsewhere in the brain. These findings provide mechanistic insight into how attention transforms percepts into memories.
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43
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Taouali W, Benvenuti G, Wallisch P, Chavane F, Perrinet LU. Testing the odds of inherent vs. observed overdispersion in neural spike counts. J Neurophysiol 2016; 115:434-44. [PMID: 26445864 PMCID: PMC4760471 DOI: 10.1152/jn.00194.2015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 10/04/2015] [Indexed: 01/15/2023] Open
Abstract
The repeated presentation of an identical visual stimulus in the receptive field of a neuron may evoke different spiking patterns at each trial. Probabilistic methods are essential to understand the functional role of this variance within the neural activity. In that case, a Poisson process is the most common model of trial-to-trial variability. For a Poisson process, the variance of the spike count is constrained to be equal to the mean, irrespective of the duration of measurements. Numerous studies have shown that this relationship does not generally hold. Specifically, a majority of electrophysiological recordings show an "overdispersion" effect: responses that exhibit more intertrial variability than expected from a Poisson process alone. A model that is particularly well suited to quantify overdispersion is the Negative-Binomial distribution model. This model is well-studied and widely used but has only recently been applied to neuroscience. In this article, we address three main issues. First, we describe how the Negative-Binomial distribution provides a model apt to account for overdispersed spike counts. Second, we quantify the significance of this model for any neurophysiological data by proposing a statistical test, which quantifies the odds that overdispersion could be due to the limited number of repetitions (trials). We apply this test to three neurophysiological data sets along the visual pathway. Finally, we compare the performance of this model to the Poisson model on a population decoding task. We show that the decoding accuracy is improved when accounting for overdispersion, especially under the hypothesis of tuned overdispersion.
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Affiliation(s)
- Wahiba Taouali
- Institut de Neurosciences de la Timone, Centre National de la Recherche Scientifique, Aix-Marseille Université, Marseille, France; and
| | - Giacomo Benvenuti
- Institut de Neurosciences de la Timone, Centre National de la Recherche Scientifique, Aix-Marseille Université, Marseille, France; and
| | - Pascal Wallisch
- Center for Neural Science, New York University, New York, New York
| | - Frédéric Chavane
- Institut de Neurosciences de la Timone, Centre National de la Recherche Scientifique, Aix-Marseille Université, Marseille, France; and
| | - Laurent U Perrinet
- Institut de Neurosciences de la Timone, Centre National de la Recherche Scientifique, Aix-Marseille Université, Marseille, France; and
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44
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Poucet B, Chaillan F, Truchet B, Save E, Sargolini F, Hok V. Is there a pilot in the brain? Contribution of the self-positioning system to spatial navigation. Front Behav Neurosci 2015; 9:292. [PMID: 26578920 PMCID: PMC4626564 DOI: 10.3389/fnbeh.2015.00292] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 10/15/2015] [Indexed: 11/13/2022] Open
Abstract
Since the discovery of place cells, the hippocampus is thought to be the neural substrate of a cognitive map. The later discovery of head direction cells, grid cells and border cells, as well as of cells with more complex spatial signals, has led to the idea that there is a brain system devoted to providing the animal with the information required to achieve efficient navigation. Current questioning is focused on how these signals are integrated in the brain. In this review, we focus on the issue of how self-localization is performed in the hippocampal place cell map. To do so, we first shortly review the sensory information used by place cells and then explain how this sensory information can lead to two coding modes, respectively based on external landmarks (allothetic information) and self-motion cues (idiothetic information). We hypothesize that these two modes can be used concomitantly with the rat shifting from one mode to the other during its spatial displacements. We then speculate that sequential reactivation of place cells could participate in the resetting of self-localization under specific circumstances and in learning a new environment. Finally, we provide some predictions aimed at testing specific aspects of the proposed ideas.
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Affiliation(s)
- Bruno Poucet
- Laboratory of Cognitive Neuroscience, CNRS and Aix-Marseille University Marseille, France ; Fédération 3C, CNRS and Aix-Marseille University Marseille, France
| | - Franck Chaillan
- Laboratory of Cognitive Neuroscience, CNRS and Aix-Marseille University Marseille, France ; Fédération 3C, CNRS and Aix-Marseille University Marseille, France
| | - Bruno Truchet
- Laboratory of Cognitive Neuroscience, CNRS and Aix-Marseille University Marseille, France ; Fédération 3C, CNRS and Aix-Marseille University Marseille, France
| | - Etienne Save
- Laboratory of Cognitive Neuroscience, CNRS and Aix-Marseille University Marseille, France ; Fédération 3C, CNRS and Aix-Marseille University Marseille, France
| | - Francesca Sargolini
- Laboratory of Cognitive Neuroscience, CNRS and Aix-Marseille University Marseille, France ; Fédération 3C, CNRS and Aix-Marseille University Marseille, France ; Institut Universitaire de France Paris, France
| | - Vincent Hok
- Laboratory of Cognitive Neuroscience, CNRS and Aix-Marseille University Marseille, France ; Fédération 3C, CNRS and Aix-Marseille University Marseille, France
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Noradrenergic signaling in the medial prefrontal cortex and amygdala differentially regulates vicarious trial-and-error in a spatial decision-making task. Behav Brain Res 2015; 297:104-11. [PMID: 26341318 DOI: 10.1016/j.bbr.2015.09.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 08/29/2015] [Accepted: 09/01/2015] [Indexed: 11/23/2022]
Abstract
In uncertain choice situations, we deliberately search and evaluate possible options before taking an action. Once we form a preference regarding the current situation, we take an action more automatically and with less deliberation. In rats, the deliberation process can be seen in vicarious trial-and-error behavior (VTE), which is a head-orienting behavior toward options at a choice point. Recent neurophysiological findings suggest that VTE reflects the rat's thinking about future options as deliberation, expectation, and planning when rats feel conflict. VTE occurs depending on the demand: an increase occurs during initial learning, and a decrease occurs with progression in learning. However, the brain circuit underlying the regulation of VTE has not been thoroughly examined. In situations in which VTE often appears, the medial prefrontal cortex (mPFC) and the amygdala (AMY) are crucial for learning and decision making. Our previous study reported that noradrenaline regulates VTE. Here, to investigate whether the mPFC and AMY are involved in regulation of VTE, we examined the effects of local injection of clonidine, an alpha2 adrenergic autoreceptor agonist, into either region in rats during VTE and choice behavior during a T-maze choice task. Injection of clonidine into either region impaired selection of the advantageous choice in the task. Furthermore, clonidine injection into the mPFC suppressed occurrence of VTE in the early phase of the task, whereas injection into the AMY inhibited the decrease in VTE in the later phase and thus maintained a high level of VTE throughout the task. These results suggest that the mPFC and AMY play a role in the increase and decrease in VTE, respectively, and that noradrenergic mechanisms mediate the dynamic regulation of VTE over experiences.
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Monasson R, Rosay S. Transitions between Spatial Attractors in Place-Cell Models. PHYSICAL REVIEW LETTERS 2015; 115:098101. [PMID: 26371684 DOI: 10.1103/physrevlett.115.098101] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Indexed: 06/05/2023]
Abstract
The spontaneous transitions between D-dimensional spatial maps in an attractor neural network are studied. Two scenarios for the transition from one map to another are found, depending on the level of noise: (i) through a mixed state, partly localized in both maps around positions where the maps are most similar, and (ii) through a weakly localized state in one of the two maps, followed by a condensation in the arrival map. Our predictions are confirmed by numerical simulations and qualitatively compared to recent recordings of hippocampal place cells during quick-environment-changing experiments in rats.
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Affiliation(s)
- R Monasson
- Laboratoire de Physique Théorique de l'Ecole Normale Supérieure, UMR 8549, associé au CNRS et à l'UPMC, 24 rue Lhomond, 75005 Paris, France
| | - S Rosay
- Laboratoire de Physique Théorique de l'Ecole Normale Supérieure, UMR 8549, associé au CNRS et à l'UPMC, 24 rue Lhomond, 75005 Paris, France
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Aly M, Turk-Browne NB. Attention Stabilizes Representations in the Human Hippocampus. Cereb Cortex 2015; 26:783-796. [PMID: 25766839 DOI: 10.1093/cercor/bhv041] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Attention and memory are intricately linked, but how attention modulates brain areas that subserve memory, such as the hippocampus, is unknown. We hypothesized that attention may stabilize patterns of activity in human hippocampus, resulting in distinct but reliable activity patterns for different attentional states. To test this prediction, we utilized high-resolution functional magnetic resonance imaging and a novel "art gallery" task. On each trial, participants viewed a room containing a painting, and searched a stream of rooms for a painting from the same artist (art state) or a room with the same layout (room state). Bottom-up stimulation was the same in both tasks, enabling the isolation of neural effects related to top-down attention. Multivariate analyses revealed greater pattern similarity in all hippocampal subfields for trials from the same, compared with different, attentional state. This stability was greater for the room than art state, was unrelated to univariate activity, and, in CA2/CA3/DG, was correlated with behavior. Attention therefore induces representational stability in the human hippocampus, resulting in distinct activity patterns for different attentional states. Modulation of hippocampal representational stability highlights the far-reaching influence of attention outside of sensory systems.
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Affiliation(s)
| | - Nicholas B Turk-Browne
- Princeton Neuroscience Institute.,Department of Psychology, Princeton University, Princeton, NJ 08544, USA
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Chadwick A, van Rossum MCW, Nolan MF. Independent theta phase coding accounts for CA1 population sequences and enables flexible remapping. eLife 2015; 4. [PMID: 25643396 PMCID: PMC4383210 DOI: 10.7554/elife.03542] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Accepted: 02/01/2015] [Indexed: 12/27/2022] Open
Abstract
Hippocampal place cells encode an animal's past, current, and future location
through sequences of action potentials generated within each cycle of the network
theta rhythm. These sequential representations have been suggested to result from
temporally coordinated synaptic interactions within and between cell assemblies.
Instead, we find through simulations and analysis of experimental data that rate and
phase coding in independent neurons is sufficient to explain the organization of CA1
population activity during theta states. We show that CA1 population activity can be
described as an evolving traveling wave that exhibits phase coding, rate coding,
spike sequences and that generates an emergent population theta rhythm. We identify
measures of global remapping and intracellular theta dynamics as critical for
distinguishing mechanisms for pacemaking and coordination of sequential population
activity. Our analysis suggests that, unlike synaptically coupled assemblies,
independent neurons flexibly generate sequential population activity within the
duration of a single theta cycle. DOI:http://dx.doi.org/10.7554/eLife.03542.001 When we explore a new place, we naturally create a mental map of the location as we
go. This mental map is stored in a region of the brain called the hippocampus, which
contains cells called place cells. These cells can carry information about our past,
present, and future location in the form of electrical signals. They connect to each
other to form networks and it has been proposed that these connections can store the
information needed for the mental maps. Real-time maps are represented in the information carried by the electrical signals
themselves. A physical location is specified by the individual place cell that is
activated, and by the timing of the electrical signal it produces relative to a
‘brain wave’ called the theta rhythm. Brain waves are patterns of
electrical signals activated in sets of brain cells and the theta rhythm is produced
in the hippocampus of an animal as it explores its surroundings. Previous experiments suggested that when a rat explores an area, several sets of
brain cells in the hippocampus are activated in sequence within each cycle of the
theta rhythm. As the rat moves forward, the sequence shifts to different sets of
cells to reflect the upcoming locations ahead of the rat. It has been thought that
these sequences are triggered by the individual connections between the place
cells. Here, Chadwick et al. developed mathematical models of the electrical activity in the
brains of rats as they explored. They used these models to analyze data from previous
experiments and found that the sequences of electrical activity arise from the timing
of each cell's activity relative to the theta rhythm, rather than from the
connections between the cells. Chadwick et al.'s findings suggest that the mental map may be highly flexible,
allowing vast numbers of distinct memories to be stored within the same network of
place cells without interference. Future studies will involve investigating the role
of brain waves in the forming new mental maps and creating new memories. DOI:http://dx.doi.org/10.7554/eLife.03542.002
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Affiliation(s)
- Angus Chadwick
- Institute for Adaptive and Neural Computation, School of Informatics, University of Edinburgh, Edinburgh, United Kingdom
| | - Mark C W van Rossum
- Institute for Adaptive and Neural Computation, School of Informatics, University of Edinburgh, Edinburgh, United Kingdom
| | - Matthew F Nolan
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
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Retrospectively and prospectively modulated hippocampal place responses are differentially distributed along a common path in a continuous T-maze. J Neurosci 2014; 34:13163-9. [PMID: 25253861 DOI: 10.1523/jneurosci.0819-14.2014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Hippocampal place responses can be prospectively or retrospectively modulated by the animal's future or prior trajectory. Two main hypotheses explain this. The "multiple-map hypothesis" switches between different maps for different trajectories (rate remapping). In contrast, in the "buffer hypothesis," the hippocampus encodes an ongoing representation that includes the recent past and/or the impending future choice. This study examines the distribution of prospective and retrospective responses distributed along a common path in a continuous T-maze (providing all four combinations of provenance and destination) during a visual discrimination task. The multiple-map hypothesis predicts either uniform distributions or concerted shifts about a task-decision relevant point, whereas the buffer hypothesis predicts a time-limited overexpression around choice points (with retrospective responses after the central arm entry point and prospective responses nearer its exit). Here bilateral recordings in the dorsal CA1 region of the rat hippocampus show that retrospective responses were twice as prevalent as prospective responses. Furthermore, retrospective and prospective modulations have distinct spatial distributions, with retrospective primarily in the first two-thirds of the central arm and prospective restricted to the last third. To test for possible trial-by-trial remapping in relation to the two-thirds transition point, data from the first and second halves of the sessions were compared. Backward drift of path-modulated activity was significant only for retrospective, but not prospective, fields. Thus, these data are more consistent with the buffer hypothesis. Retrospective and prospective modulation would then participate in a single hippocampal representation of spatial and behavioral context.
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Abstract
Spatial information about the environment is encoded by the activity of place and grid cells in the hippocampal formation. As an animal traverses a cell's firing field, action potentials progressively shift to earlier phases of the theta oscillation (6-10 Hz). This "phase precession" is observed also in the prefrontal cortex and the ventral striatum, but mechanisms for its generation are unknown. However, once phase precession exists in one region, it might also propagate to downstream regions. Using a computational model, we analyze such inheritance of phase precession, for example, from the entorhinal cortex to CA1 and from CA3 to CA1. We find that distinctive subthreshold and suprathreshold features of the membrane potential of CA1 pyramidal cells (Harvey et al., 2009; Mizuseki et al., 2012; Royer et al., 2012) can be explained by inheritance and that excitatory input is essential. The model explains how inhibition modulates the slope and range of phase precession and provides two main testable predictions. First, theta-modulated inhibitory input to a CA1 pyramidal cell is not necessary for phase precession. Second, theta-modulated inhibitory input on its own generates membrane potential peaks that are in phase with peaks of the extracellular field. Furthermore, we suggest that the spatial distribution of field centers of a population of phase-precessing input cells determines, not only the place selectivity, but also the characteristics of phase precession of the targeted output cell. The inheritance model thus can explain why phase precession is observed throughout the hippocampal formation and other areas of the brain.
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