1
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Varga V, Petersen P, Zutshi I, Huszar R, Zhang Y, Buzsáki G. Working memory features are embedded in hippocampal place fields. Cell Rep 2024; 43:113807. [PMID: 38401118 PMCID: PMC11044127 DOI: 10.1016/j.celrep.2024.113807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 12/13/2023] [Accepted: 01/31/2024] [Indexed: 02/26/2024] Open
Abstract
Hippocampal principal neurons display both spatial tuning properties and memory features. Whether this distinction corresponds to separate neuron types or a context-dependent continuum has been debated. We report here that the task-context ("splitter") feature is highly variable along both trial and spatial position axes. Neurons acquire or lose splitter features across trials even when place field features remain unaltered. Multiple place fields of the same neuron can individually encode both past or future run trajectories, implying that splitter fields are under the control of assembly activity. Place fields can be differentiated into subfields by the behavioral choice of the animal, and splitting within subfields evolves across trials. Interneurons also differentiate choices by integrating inputs from pyramidal cells. Finally, bilateral optogenetic inactivation of the medial entorhinal cortex reversibly decreases the fraction of splitter fields. Our findings suggest that place or splitter features are different manifestations of the same hippocampal computation.
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Affiliation(s)
- Viktor Varga
- Neuroscience Institute, Langone Health, New York University, New York, NY, USA; Subcortical Modulation Research Group, Institute of Experimental Medicine - Hungarian Research Network, Budapest, Hungary
| | - Peter Petersen
- Neuroscience Institute, Langone Health, New York University, New York, NY, USA; Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
| | - Ipshita Zutshi
- Neuroscience Institute, Langone Health, New York University, New York, NY, USA
| | - Roman Huszar
- Neuroscience Institute, Langone Health, New York University, New York, NY, USA
| | - Yiyao Zhang
- Neuroscience Institute, Langone Health, New York University, New York, NY, USA
| | - György Buzsáki
- Neuroscience Institute, Langone Health, New York University, New York, NY, USA; Department of Neuroscience and Physiology, Langone Health, New York University, New York, NY, USA; Department of Neurology, Langone Health, New York University, New York, NY, USA.
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2
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Robinson JC, Wilmot JH, Hasselmo ME. Septo-hippocampal dynamics and the encoding of space and time. Trends Neurosci 2023; 46:712-725. [PMID: 37479632 PMCID: PMC10538955 DOI: 10.1016/j.tins.2023.06.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Revised: 05/12/2023] [Accepted: 06/27/2023] [Indexed: 07/23/2023]
Abstract
Encoding an event in memory requires neural activity to represent multiple dimensions of behavioral experience in space and time. Recent experiments have explored the influence of neural dynamics regulated by the medial septum on the functional encoding of space and time by neurons in the hippocampus and associated structures. This review addresses these dynamics, focusing on the role of theta rhythm, the differential effects of septal inactivation and activation on the functional coding of space and time by individual neurons, and the influence on phase coding that appears as phase precession. We also discuss data indicating that theta rhythm plays a role in timing the internal dynamics of memory encoding and retrieval, as well as the behavioral influences of these neuronal manipulations with regard to memory function.
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Affiliation(s)
- Jennifer C Robinson
- Center for Systems Neuroscience, Boston University, 610 Commonwealth Avenue, Boston, MA 02215, USA.
| | - Jacob H Wilmot
- Center for Systems Neuroscience, Boston University, 610 Commonwealth Avenue, Boston, MA 02215, USA.
| | - Michael E Hasselmo
- Center for Systems Neuroscience, Boston University, 610 Commonwealth Avenue, Boston, MA 02215, USA.
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3
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Kim SH, GoodSmith D, Temme SJ, Moriya F, Ming GL, Christian KM, Song H, Knierim JJ. Global remapping in granule cells and mossy cells of the mouse dentate gyrus. Cell Rep 2023; 42:112334. [PMID: 37043350 PMCID: PMC10564968 DOI: 10.1016/j.celrep.2023.112334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 02/02/2023] [Accepted: 03/17/2023] [Indexed: 04/13/2023] Open
Abstract
Hippocampal place cells exhibit spatially modulated firing, or place fields, which can remap to encode changes in the environment or other variables. Unique among hippocampal subregions, the dentate gyrus (DG) has two excitatory populations of place cells, granule cells and mossy cells, which are among the least and most active spatially modulated cells in the hippocampus, respectively. Previous studies of remapping in the DG have drawn different conclusions about whether granule cells exhibit global remapping and contribute to the encoding of context specificity. By recording granule cells and mossy cells as mice foraged in different environments, we found that by most measures, both granule cells and mossy cells remapped robustly but through different mechanisms that are consistent with firing properties of each cell type. Our results resolve the ambiguity surrounding remapping in the DG and suggest that most spatially modulated granule cells contribute to orthogonal representations of distinct spatial contexts.
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Affiliation(s)
- Sang Hoon Kim
- Department of Neuroscience and Mahoney Institute for Neurosciences, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Douglas GoodSmith
- Department of Neuroscience and Mahoney Institute for Neurosciences, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Zanvyl Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, MD 21218, USA; The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Neurobiology and Neuroscience Institute, University of Chicago, Chicago, IL 60637, USA
| | - Stephanie J Temme
- Department of Neuroscience and Mahoney Institute for Neurosciences, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Fumika Moriya
- Department of Neuroscience and Mahoney Institute for Neurosciences, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Guo-Li Ming
- Department of Neuroscience and Mahoney Institute for Neurosciences, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Institute for Regenerative Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Kimberly M Christian
- Department of Neuroscience and Mahoney Institute for Neurosciences, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Hongjun Song
- Department of Neuroscience and Mahoney Institute for Neurosciences, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Institute for Regenerative Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; The Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - James J Knierim
- Zanvyl Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, MD 21218, USA; The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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4
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Wilmerding LK, Kondratyev I, Ramirez S, Hasselmo ME. Route-dependent spatial engram tagging in mouse dentate gyrus. Neurobiol Learn Mem 2023; 200:107738. [PMID: 36822466 PMCID: PMC10106405 DOI: 10.1016/j.nlm.2023.107738] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 01/30/2023] [Accepted: 02/16/2023] [Indexed: 02/23/2023]
Abstract
The dentate gyrus (DG) of hippocampus is hypothesized to act as a pattern separator that distinguishes between similar input patterns during memory formation and retrieval. Sparse ensembles of DG cells associated with learning and memory, i.e. engrams, have been labeled and manipulated to recall novel context memories. Functional studies of DG cell activity have demonstrated the spatial specificity and stability of DG cells during navigation. To reconcile how the DG contributes to separating global context as well as individual navigational routes, we trained mice to perform a delayed-non-match-to-position (DNMP) T-maze task and labeled DG neurons during performance of this task on a novel T-maze. The following day, mice navigated a second environment: the same T-maze, the same T-maze with one route permanently blocked but still visible, or a novel open field. We found that the degree of engram reactivation across days differed based on the traversal of maze routes, such that mice traversing only one arm had higher ensemble overlap than chance but less overlap than mice running the full two-route task. Mice experiencing the open field had similar ensemble sizes to the other groups but only chance-level ensemble reactivation. Ensemble overlap differences could not be explained by behavioral variability across groups, nor did behavioral metrics correlate to degree of ensemble reactivation. Together, these results support the hypothesis that DG contributes to spatial navigation memory and that partially non-overlapping ensembles encode different routes within the context of an environment.
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Affiliation(s)
- Lucius K Wilmerding
- Center for Systems Neuroscience, Boston University, United States; Graduate Program for Neuroscience, Boston University, United States; Department of Psychological and Brain Sciences, Boston University, United States.
| | - Ivan Kondratyev
- Center for Systems Neuroscience, Boston University, United States
| | - Steve Ramirez
- Center for Systems Neuroscience, Boston University, United States; Graduate Program for Neuroscience, Boston University, United States; Department of Psychological and Brain Sciences, Boston University, United States
| | - Michael E Hasselmo
- Center for Systems Neuroscience, Boston University, United States; Graduate Program for Neuroscience, Boston University, United States; Department of Psychological and Brain Sciences, Boston University, United States
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5
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Duvelle É, Grieves RM, van der Meer MAA. Temporal context and latent state inference in the hippocampal splitter signal. eLife 2023; 12:e82357. [PMID: 36622350 PMCID: PMC9829411 DOI: 10.7554/elife.82357] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 12/06/2022] [Indexed: 01/10/2023] Open
Abstract
The hippocampus is thought to enable the encoding and retrieval of ongoing experience, the organization of that experience into structured representations like contexts, maps, and schemas, and the use of these structures to plan for the future. A central goal is to understand what the core computations supporting these functions are, and how these computations are realized in the collective action of single neurons. A potential access point into this issue is provided by 'splitter cells', hippocampal neurons that fire differentially on the overlapping segment of trajectories that differ in their past and/or future. However, the literature on splitter cells has been fragmented and confusing, owing to differences in terminology, behavioral tasks, and analysis methods across studies. In this review, we synthesize consistent findings from this literature, establish a common set of terms, and translate between single-cell and ensemble perspectives. Most importantly, we examine the combined findings through the lens of two major theoretical ideas about hippocampal function: representation of temporal context and latent state inference. We find that unique signature properties of each of these models are necessary to account for the data, but neither theory, by itself, explains all of its features. Specifically, the temporal gradedness of the splitter signal is strong support for temporal context, but is hard to explain using state models, while its flexibility and task-dependence is naturally accounted for using state inference, but poses a challenge otherwise. These theories suggest a number of avenues for future work, and we believe their application to splitter cells is a timely and informative domain for testing and refining theoretical ideas about hippocampal function.
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Affiliation(s)
- Éléonore Duvelle
- Department of Psychological and Brain Sciences, Dartmouth CollegeHanoverUnited States
| | - Roddy M Grieves
- Department of Psychological and Brain Sciences, Dartmouth CollegeHanoverUnited States
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6
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Wirtshafter HS, Disterhoft JF. In Vivo Multi-Day Calcium Imaging of CA1 Hippocampus in Freely Moving Rats Reveals a High Preponderance of Place Cells with Consistent Place Fields. J Neurosci 2022; 42:4538-4554. [PMID: 35501152 PMCID: PMC9172072 DOI: 10.1523/jneurosci.1750-21.2022] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 04/15/2022] [Accepted: 04/19/2022] [Indexed: 11/21/2022] Open
Abstract
Calcium imaging using GCaMP indicators and miniature microscopes has been used to image cellular populations during long timescales and in different task phases, as well as to determine neuronal circuit topology and organization. Because the hippocampus (HPC) is essential for tasks of memory, spatial navigation, and learning, calcium imaging of large populations of HPC neurons can provide new insight on cell changes over time during these tasks. All reported HPC in vivo calcium imaging experiments have been done in mouse. However, rats have many behavioral and physiological experimental advantages over mice. In this paper, we present the first (to our knowledge) in vivo calcium imaging from CA1 HPC in freely moving male rats. Using the UCLA Miniscope, we demonstrate that, in rat, hundreds of cells can be visualized and held across weeks. We show that calcium events in these cells are highly correlated with periods of movement, with few calcium events occurring during periods without movement. We additionally show that an extremely large percent of cells recorded during a navigational task are place cells (77.3 ± 5.0%, surpassing the percent seen during mouse calcium imaging), and that these cells enable accurate decoding of animal position and can be held over days with consistent place fields in a consistent spatial map. A detailed protocol is included, and implications of these advancements on in vivo imaging and place field literature are discussed.SIGNIFICANCE STATEMENT In vivo calcium imaging in freely moving animals allows the visualization of cellular activity across days. In this paper, we present the first in vivo Ca2+ recording from CA1 hippocampus (HPC) in freely moving rats. We demonstrate that hundreds of cells can be visualized and held across weeks, and that calcium activity corresponds to periods of movement. We show that a high percentage (77.3 ± 5.0%) of imaged cells are place cells, and that these place cells enable accurate decoding and can be held stably over days with little change in field location. Because the HPC is essential for many tasks involving memory, navigation, and learning, imaging of large populations of HPC neurons can shed new insight on cellular activity changes and organization.
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Affiliation(s)
- Hannah S Wirtshafter
- Department of Neuroscience, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611
| | - John F Disterhoft
- Department of Neuroscience, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611
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7
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Johnson C, Kretsge LN, Yen WW, Sriram B, O'Connor A, Liu RS, Jimenez JC, Phadke RA, Wingfield KK, Yeung C, Jinadasa TJ, Nguyen TPH, Cho ES, Fuchs E, Spevack ED, Velasco BE, Hausmann FS, Fournier LA, Brack A, Melzer S, Cruz-Martín A. Highly unstable heterogeneous representations in VIP interneurons of the anterior cingulate cortex. Mol Psychiatry 2022; 27:2602-2618. [PMID: 35246635 PMCID: PMC11128891 DOI: 10.1038/s41380-022-01485-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 02/07/2022] [Accepted: 02/09/2022] [Indexed: 11/09/2022]
Abstract
A hallmark of the anterior cingulate cortex (ACC) is its functional heterogeneity. Functional and imaging studies revealed its importance in the encoding of anxiety-related and social stimuli, but it is unknown how microcircuits within the ACC encode these distinct stimuli. One type of inhibitory interneuron, which is positive for vasoactive intestinal peptide (VIP), is known to modulate the activity of pyramidal cells in local microcircuits, but it is unknown whether VIP cells in the ACC (VIPACC) are engaged by particular contexts or stimuli. Additionally, recent studies demonstrated that neuronal representations in other cortical areas can change over time at the level of the individual neuron. However, it is not known whether stimulus representations in the ACC remain stable over time. Using in vivo Ca2+ imaging and miniscopes in freely behaving mice to monitor neuronal activity with cellular resolution, we identified individual VIPACC that preferentially activated to distinct stimuli across diverse tasks. Importantly, although the population-level activity of the VIPACC remained stable across trials, the stimulus-selectivity of individual interneurons changed rapidly. These findings demonstrate marked functional heterogeneity and instability within interneuron populations in the ACC. This work contributes to our understanding of how the cortex encodes information across diverse contexts and provides insight into the complexity of neural processes involved in anxiety and social behavior.
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Affiliation(s)
- Connor Johnson
- Neurobiology Section in the Department of Biology, Boston University, Boston, MA, USA
| | - Lisa N Kretsge
- The Graduate Program for Neuroscience, Boston University, Boston, MA, USA
- Neurophotonics Center, Boston University, Boston, MA, USA
| | - William W Yen
- Neurobiology Section in the Department of Biology, Boston University, Boston, MA, USA
| | | | - Alexandra O'Connor
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Ruichen Sky Liu
- MS in Statistical Practice Program, Boston University, Boston, MA, USA
| | - Jessica C Jimenez
- Department of Neurology, University of California, San Francisco, San Francisco, CA, USA
| | - Rhushikesh A Phadke
- Molecular Biology, Cell Biology and Biochemistry Program, Boston University, Boston, MA, USA
| | - Kelly K Wingfield
- Neurophotonics Center, Boston University, Boston, MA, USA
- Department of Pharmacology and Experimental Therapeutics, Boston University, Boston, MA, USA
| | - Charlotte Yeung
- Neurobiology Section in the Department of Biology, Boston University, Boston, MA, USA
| | - Tushare J Jinadasa
- Neurobiology Section in the Department of Biology, Boston University, Boston, MA, USA
| | - Thanh P H Nguyen
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Eun Seon Cho
- Neurobiology Section in the Department of Biology, Boston University, Boston, MA, USA
| | - Erelle Fuchs
- Neurobiology Section in the Department of Biology, Boston University, Boston, MA, USA
| | - Eli D Spevack
- Neurobiology Section in the Department of Biology, Boston University, Boston, MA, USA
| | - Berta Escude Velasco
- Neurobiology Section in the Department of Biology, Boston University, Boston, MA, USA
| | - Frances S Hausmann
- Neurobiology Section in the Department of Biology, Boston University, Boston, MA, USA
| | - Luke A Fournier
- Neurobiology Section in the Department of Biology, Boston University, Boston, MA, USA
| | - Alison Brack
- Molecular Biology, Cell Biology and Biochemistry Program, Boston University, Boston, MA, USA
| | - Sarah Melzer
- Department of Neurobiology, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA
| | - Alberto Cruz-Martín
- Neurobiology Section in the Department of Biology, Boston University, Boston, MA, USA.
- Neurophotonics Center, Boston University, Boston, MA, USA.
- Molecular Biology, Cell Biology and Biochemistry Program, Boston University, Boston, MA, USA.
- Center for Systems Neuroscience, Boston University, Boston, MA, USA.
- The Center for Network Systems Biology, Boston University, Boston, MA, USA.
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8
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Liberti WA, Schmid TA, Forli A, Snyder M, Yartsev MM. A stable hippocampal code in freely flying bats. Nature 2022; 604:98-103. [PMID: 35355012 PMCID: PMC10212506 DOI: 10.1038/s41586-022-04560-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 02/17/2022] [Indexed: 12/31/2022]
Abstract
Neural activity in the hippocampus is known to reflect how animals move through an environment1,2. Although navigational behaviour may show considerable stability3-6, the tuning stability of individual hippocampal neurons remains unclear7-12. Here we used wireless calcium imaging to longitudinally monitor the activity of dorsal CA1 hippocampal neurons in freely flying bats performing highly reproducible flights in a familiar environment. We find that both the participation and the spatial selectivity of most neurons remain stable over days and weeks. We also find that apparent changes in tuning can be largely attributed to variations in the flight behaviour of the bats. Finally, we show that bats navigating in the same environment under different room lighting conditions (lights on versus lights off) exhibit substantial changes in flight behaviour that can give the illusion of neuronal instability. However, when similar flight paths are compared across conditions, the stability of the hippocampal code persists. Taken together, we show that the underlying hippocampal code is highly stable over days and across contexts if behaviour is taken into account.
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Affiliation(s)
| | - Tobias A Schmid
- Helen Wills Neuroscience Institute, UC Berkeley, Berkeley, CA, USA
| | - Angelo Forli
- Department of Bioengineering, UC Berkeley, Berkeley, CA, USA
| | | | - Michael M Yartsev
- Department of Bioengineering, UC Berkeley, Berkeley, CA, USA.
- Helen Wills Neuroscience Institute, UC Berkeley, Berkeley, CA, USA.
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9
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Liu Y, Levy S, Mau W, Geva N, Rubin A, Ziv Y, Hasselmo M, Howard M. Consistent population activity on the scale of minutes in the mouse hippocampus. Hippocampus 2022; 32:359-372. [PMID: 35225408 PMCID: PMC10085730 DOI: 10.1002/hipo.23409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 01/05/2022] [Accepted: 01/31/2022] [Indexed: 11/09/2022]
Abstract
Neurons in the hippocampus fire in consistent sequence over the timescale of seconds during the delay period of some memory experiments. For longer timescales, the firing of hippocampal neurons also changes slowly over minutes within experimental sessions. It was thought that these slow dynamics are caused by stochastic drift or a continuous change in the representation of the episode, rather than consistent sequences unfolding over minutes. This paper studies the consistency of contextual drift in three chronic calcium imaging recordings from the hippocampus CA1 region in mice. Computational measures of consistency show reliable sequences within experimental trials at the scale of seconds as one would expect from time cells or place cells during the trial, as well as across experimental trials on the scale of minutes within a recording session. Consistent sequences in the hippocampus are observed over a wide range of time scales, from seconds to minutes. The hippocampal activity could reflect a scale-invariant spatiotemporal context as suggested by theories of memory from cognitive psychology.
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Affiliation(s)
- Yue Liu
- Department of Physics, Boston University, Boston, Massachusetts, USA.,Center for Systems Neuroscience, Boston University, Boston, Massachusetts, USA.,Center for Memory and Brain, Boston University, Boston, Massachusetts, USA
| | - Samuel Levy
- Center for Systems Neuroscience, Boston University, Boston, Massachusetts, USA.,Center for Memory and Brain, Boston University, Boston, Massachusetts, USA.,Department of Psychological and Brain Sciences, Boston University, Boston, Massachusetts, USA
| | - William Mau
- Center for Systems Neuroscience, Boston University, Boston, Massachusetts, USA.,Center for Memory and Brain, Boston University, Boston, Massachusetts, USA.,Department of Psychological and Brain Sciences, Boston University, Boston, Massachusetts, USA
| | - Nitzan Geva
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
| | - Alon Rubin
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
| | - Yaniv Ziv
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
| | - Michael Hasselmo
- Center for Systems Neuroscience, Boston University, Boston, Massachusetts, USA.,Center for Memory and Brain, Boston University, Boston, Massachusetts, USA.,Department of Psychological and Brain Sciences, Boston University, Boston, Massachusetts, USA
| | - Marc Howard
- Department of Physics, Boston University, Boston, Massachusetts, USA.,Center for Systems Neuroscience, Boston University, Boston, Massachusetts, USA.,Center for Memory and Brain, Boston University, Boston, Massachusetts, USA.,Department of Psychological and Brain Sciences, Boston University, Boston, Massachusetts, USA
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10
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Self-healing codes: How stable neural populations can track continually reconfiguring neural representations. Proc Natl Acad Sci U S A 2022; 119:2106692119. [PMID: 35145024 PMCID: PMC8851551 DOI: 10.1073/pnas.2106692119] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/29/2021] [Indexed: 12/19/2022] Open
Abstract
The brain is capable of adapting while maintaining stable long-term memories and learned skills. Recent experiments show that neural responses are highly plastic in some circuits, while other circuits maintain consistent responses over time, raising the question of how these circuits interact coherently. We show how simple, biologically motivated Hebbian and homeostatic mechanisms in single neurons can allow circuits with fixed responses to continuously track a plastic, changing representation without reference to an external learning signal. As an adaptive system, the brain must retain a faithful representation of the world while continuously integrating new information. Recent experiments have measured population activity in cortical and hippocampal circuits over many days and found that patterns of neural activity associated with fixed behavioral variables and percepts change dramatically over time. Such “representational drift” raises the question of how malleable population codes can interact coherently with stable long-term representations that are found in other circuits and with relatively rigid topographic mappings of peripheral sensory and motor signals. We explore how known plasticity mechanisms can allow single neurons to reliably read out an evolving population code without external error feedback. We find that interactions between Hebbian learning and single-cell homeostasis can exploit redundancy in a distributed population code to compensate for gradual changes in tuning. Recurrent feedback of partially stabilized readouts could allow a pool of readout cells to further correct inconsistencies introduced by representational drift. This shows how relatively simple, known mechanisms can stabilize neural tuning in the short term and provides a plausible explanation for how plastic neural codes remain integrated with consolidated, long-term representations.
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11
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Abstract
The investigation of the topographic organization of spatially coding cell types in the medial entorhinal cortex (MEC) has so far been held back by the lack of appropriate tools that enable the precise recording of both the anatomical location and activity of large populations of cells while animals forage in open environments. In this study, we use the newest generation of head-mounted, miniaturized two-photon microscopes to image grid, head-direction, border, as well as object-vector cells in MEC and neighboring parasubiculum within the same animals. The majority of cell types were intermingled, but grid and object-vector cells exhibited little overlap. The results have implications for network models of spatial coding. The medial entorhinal cortex (MEC) creates a map of local space, based on the firing patterns of grid, head-direction (HD), border, and object-vector (OV) cells. How these cell types are organized anatomically is debated. In-depth analysis of this question requires collection of precise anatomical and activity data across large populations of neurons during unrestrained behavior, which neither electrophysiological nor previous imaging methods fully afford. Here, we examined the topographic arrangement of spatially modulated neurons in the superficial layers of MEC and adjacent parasubiculum using miniaturized, portable two-photon microscopes, which allow mice to roam freely in open fields. Grid cells exhibited low levels of co-occurrence with OV cells and clustered anatomically, while border, HD, and OV cells tended to intermingle. These data suggest that grid cell networks might be largely distinct from those of border, HD, and OV cells and that grid cells exhibit strong coupling among themselves but weaker links to other cell types.
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12
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Nyberg N, Duvelle É, Barry C, Spiers HJ. Spatial goal coding in the hippocampal formation. Neuron 2022; 110:394-422. [PMID: 35032426 DOI: 10.1016/j.neuron.2021.12.012] [Citation(s) in RCA: 42] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 10/18/2021] [Accepted: 12/08/2021] [Indexed: 12/22/2022]
Abstract
The mammalian hippocampal formation contains several distinct populations of neurons involved in representing self-position and orientation. These neurons, which include place, grid, head direction, and boundary-vector cells, are thought to collectively instantiate cognitive maps supporting flexible navigation. However, to flexibly navigate, it is necessary to also maintain internal representations of goal locations, such that goal-directed routes can be planned and executed. Although it has remained unclear how the mammalian brain represents goal locations, multiple neural candidates have recently been uncovered during different phases of navigation. For example, during planning, sequential activation of spatial cells may enable simulation of future routes toward the goal. During travel, modulation of spatial cells by the prospective route, or by distance and direction to the goal, may allow maintenance of route and goal-location information, supporting navigation on an ongoing basis. As the goal is approached, an increased activation of spatial cells may enable the goal location to become distinctly represented within cognitive maps, aiding goal localization. Lastly, after arrival at the goal, sequential activation of spatial cells may represent the just-taken route, enabling route learning and evaluation. Here, we review and synthesize these and other evidence for goal coding in mammalian brains, relate the experimental findings to predictions from computational models, and discuss outstanding questions and future challenges.
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Affiliation(s)
- Nils Nyberg
- Institute of Behavioural Neuroscience, Department of Experimental Psychology, University College London, London, UK.
| | - Éléonore Duvelle
- Department of Psychological and Brain Sciences, Dartmouth College, Hanover, NH, USA
| | - Caswell Barry
- Department of Cell and Developmental Biology, University College London, London, UK
| | - Hugo J Spiers
- Institute of Behavioural Neuroscience, Department of Experimental Psychology, University College London, London, UK.
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13
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Carstensen LC, Alexander AS, Chapman GW, Lee AJ, Hasselmo ME. Neural responses in retrosplenial cortex associated with environmental alterations. iScience 2021; 24:103377. [PMID: 34825142 PMCID: PMC8605176 DOI: 10.1016/j.isci.2021.103377] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 09/14/2021] [Accepted: 10/26/2021] [Indexed: 11/26/2022] Open
Abstract
The retrosplenial cortex (RSC) is an area interconnected with regions of the brain that display spatial correlates. Neurons in connected regions may encode an animal’s position in the environment and location or proximity to objects or boundaries. RSC has also been shown to be important for spatial memory, such as tracking distance from and between landmarks, contextual information, and orientation within an environment. For these reasons, it is important to determine how neurons in RSC represent cues such as objects or boundaries and their relationship to the environment. In the current work, we performed electrophysiological recordings in RSC, whereas rats foraged in arenas that could contain an object or in which the environment was altered. We report RSC neurons display changes in mean firing rate responding to alterations of the environment. These alterations include the arena rotating, changing size or shape, or an object being introduced into the arena. Insertion of an object induces a change in mean firing rate in retrosplenial neurons Cells that change mean firing rate (MFR) are not driven by speed modulation Population representation changes over time, but not in cells with MFR changes Manipulation of environmental features induces a change in mean firing rate
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Affiliation(s)
- Lucas C Carstensen
- Center for Systems Neuroscience, Boston University, 610 Commonwealth Avenue, Boston, MA 02215, USA.,Department of Psychological and Brain Sciences, Boston University, 610 Commonwealth Avenue, Boston, MA 02215, USA.,Graduate Program for Neuroscience, Boston University, 610 Commonwealth Avenue, Boston, MA 02215, USA
| | - Andrew S Alexander
- Center for Systems Neuroscience, Boston University, 610 Commonwealth Avenue, Boston, MA 02215, USA.,Department of Psychological and Brain Sciences, Boston University, 610 Commonwealth Avenue, Boston, MA 02215, USA
| | - G William Chapman
- Center for Systems Neuroscience, Boston University, 610 Commonwealth Avenue, Boston, MA 02215, USA.,Department of Psychological and Brain Sciences, Boston University, 610 Commonwealth Avenue, Boston, MA 02215, USA
| | - Aubrey J Lee
- Center for Systems Neuroscience, Boston University, 610 Commonwealth Avenue, Boston, MA 02215, USA
| | - Michael E Hasselmo
- Center for Systems Neuroscience, Boston University, 610 Commonwealth Avenue, Boston, MA 02215, USA.,Department of Psychological and Brain Sciences, Boston University, 610 Commonwealth Avenue, Boston, MA 02215, USA.,Graduate Program for Neuroscience, Boston University, 610 Commonwealth Avenue, Boston, MA 02215, USA
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14
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Griffin AL. The nucleus reuniens orchestrates prefrontal-hippocampal synchrony during spatial working memory. Neurosci Biobehav Rev 2021; 128:415-420. [PMID: 34217746 DOI: 10.1016/j.neubiorev.2021.05.033] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 05/07/2021] [Accepted: 05/10/2021] [Indexed: 12/11/2022]
Abstract
Spatial working memory, the ability to temporarily maintain an internal representation of spatial information for use in guiding upcoming decisions, has been shown to be dependent upon a network of brain structures that includes the hippocampus, a region known to be critical for spatial navigation and episodic memory, and the prefrontal cortex (PFC), a region known to be critical for executive function and goal directed behavior. Oscillatory synchronization between the hippocampus and the prefrontal cortex (PFC) is known to increase in situations of high working memory demand. Most of our knowledge about the anatomical connectivity between the PFC and hippocampus comes from the rodent literature. Thus, most of the findings that will be discussed here model human working memory using spatial working memory-dependent maze navigation tasks in rodents. It has been demonstrated that the ventral midline thalamic nucleus reuniens (Re) is reciprocally connected to both the infralimbic and prelimbic subregions of the PFC, collectively referred to as the medial PFC (mPFC), and the hippocampus. Given that the Re serves as a major anatomical route between the mPFC and hippocampus, it is perhaps not surprising that Re has been shown to be critical for spatial working memory. This review will describe the latest findings and ideas on how the Re contributes to prefrontal-hippocampal synchronization and spatial working memory in rodents. The review will conclude with possible future directions that will advance the understanding of the mechanisms that enable the Re to orchestrate long range synchrony in the prefrontal-hippocampal network.
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Affiliation(s)
- Amy L Griffin
- University of Delaware, Newark, DE, 19711, United States.
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15
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Mau W, Hasselmo ME, Cai DJ. The brain in motion: How ensemble fluidity drives memory-updating and flexibility. eLife 2020; 9:e63550. [PMID: 33372892 PMCID: PMC7771967 DOI: 10.7554/elife.63550] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 12/12/2020] [Indexed: 12/18/2022] Open
Abstract
While memories are often thought of as flashbacks to a previous experience, they do not simply conserve veridical representations of the past but must continually integrate new information to ensure survival in dynamic environments. Therefore, 'drift' in neural firing patterns, typically construed as disruptive 'instability' or an undesirable consequence of noise, may actually be useful for updating memories. In our view, continual modifications in memory representations reconcile classical theories of stable memory traces with neural drift. Here we review how memory representations are updated through dynamic recruitment of neuronal ensembles on the basis of excitability and functional connectivity at the time of learning. Overall, we emphasize the importance of considering memories not as static entities, but instead as flexible network states that reactivate and evolve across time and experience.
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Affiliation(s)
- William Mau
- Neuroscience Department, Icahn School of Medicine at Mount SinaiNew YorkUnited States
| | | | - Denise J Cai
- Neuroscience Department, Icahn School of Medicine at Mount SinaiNew YorkUnited States
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Rule ME, Loback AR, Raman DV, Driscoll LN, Harvey CD, O'Leary T. Stable task information from an unstable neural population. eLife 2020; 9:51121. [PMID: 32660692 PMCID: PMC7392606 DOI: 10.7554/elife.51121] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Accepted: 06/17/2020] [Indexed: 02/06/2023] Open
Abstract
Over days and weeks, neural activity representing an animal's position and movement in sensorimotor cortex has been found to continually reconfigure or 'drift' during repeated trials of learned tasks, with no obvious change in behavior. This challenges classical theories, which assume stable engrams underlie stable behavior. However, it is not known whether this drift occurs systematically, allowing downstream circuits to extract consistent information. Analyzing long-term calcium imaging recordings from posterior parietal cortex in mice (Mus musculus), we show that drift is systematically constrained far above chance, facilitating a linear weighted readout of behavioral variables. However, a significant component of drift continually degrades a fixed readout, implying that drift is not confined to a null coding space. We calculate the amount of plasticity required to compensate drift independently of any learning rule, and find that this is within physiologically achievable bounds. We demonstrate that a simple, biologically plausible local learning rule can achieve these bounds, accurately decoding behavior over many days.
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Affiliation(s)
- Michael E Rule
- Department of Engineering, University of Cambridge, Cambridge, United Kingdom
| | - Adrianna R Loback
- Department of Engineering, University of Cambridge, Cambridge, United Kingdom
| | - Dhruva V Raman
- Department of Engineering, University of Cambridge, Cambridge, United Kingdom
| | - Laura N Driscoll
- Department of Electrical Engineering, Stanford University, Stanford, United States
| | | | - Timothy O'Leary
- Department of Engineering, University of Cambridge, Cambridge, United Kingdom
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17
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Alexander AS, Robinson JC, Dannenberg H, Kinsky NR, Levy SJ, Mau W, Chapman GW, Sullivan DW, Hasselmo ME. Neurophysiological coding of space and time in the hippocampus, entorhinal cortex, and retrosplenial cortex. Brain Neurosci Adv 2020; 4:2398212820972871. [PMID: 33294626 PMCID: PMC7708714 DOI: 10.1177/2398212820972871] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 10/21/2020] [Indexed: 11/18/2022] Open
Abstract
Neurophysiological recordings in behaving rodents demonstrate neuronal response properties that may code space and time for episodic memory and goal-directed behaviour. Here, we review recordings from hippocampus, entorhinal cortex, and retrosplenial cortex to address the problem of how neurons encode multiple overlapping spatiotemporal trajectories and disambiguate these for accurate memory-guided behaviour. The solution could involve neurons in the entorhinal cortex and hippocampus that show mixed selectivity, coding both time and location. Some grid cells and place cells that code space also respond selectively as time cells, allowing differentiation of time intervals when a rat runs in the same location during a delay period. Cells in these regions also develop new representations that differentially code the context of prior or future behaviour allowing disambiguation of overlapping trajectories. Spiking activity is also modulated by running speed and head direction, supporting the coding of episodic memory not as a series of snapshots but as a trajectory that can also be distinguished on the basis of speed and direction. Recent data also address the mechanisms by which sensory input could distinguish different spatial locations. Changes in firing rate reflect running speed on long but not short time intervals, and few cells code movement direction, arguing against path integration for coding location. Instead, new evidence for neural coding of environmental boundaries in egocentric coordinates fits with a modelling framework in which egocentric coding of barriers combined with head direction generates distinct allocentric coding of location. The egocentric input can be used both for coding the location of spatiotemporal trajectories and for retrieving specific viewpoints of the environment. Overall, these different patterns of neural activity can be used for encoding and disambiguation of prior episodic spatiotemporal trajectories or for planning of future goal-directed spatiotemporal trajectories.
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Affiliation(s)
| | | | | | | | - Samuel J. Levy
- Center for Systems Neuroscience, Boston University, Boston, MA, USA
| | - William Mau
- Center for Systems Neuroscience, Boston University, Boston, MA, USA
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