1
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Boyle LM, Posani L, Irfan S, Siegelbaum SA, Fusi S. Tuned geometries of hippocampal representations meet the computational demands of social memory. Neuron 2024; 112:1358-1371.e9. [PMID: 38382521 PMCID: PMC11186585 DOI: 10.1016/j.neuron.2024.01.021] [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: 06/16/2023] [Revised: 11/03/2023] [Accepted: 01/19/2024] [Indexed: 02/23/2024]
Abstract
Social memory consists of two processes: the detection of familiar compared with novel conspecifics and the detailed recollection of past social episodes. We investigated the neural bases for these processes using calcium imaging of dorsal CA2 hippocampal pyramidal neurons, known to be important for social memory, during social/spatial encounters with novel conspecifics and familiar littermates. Whereas novel individuals were represented in a low-dimensional geometry that allows for generalization of social identity across different spatial locations and of location across different identities, littermates were represented in a higher-dimensional geometry that supports high-capacity memory storage. Moreover, familiarity was represented in an abstract format, independent of individual identity. The degree to which familiarity increased the dimensionality of CA2 representations for individual mice predicted their performance in a social novelty recognition memory test. Thus, by tuning the geometry of structured neural activity, CA2 is able to meet the demands of distinct social memory processes.
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Affiliation(s)
- Lara M Boyle
- Department of Neuroscience, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, NY 10027, USA
| | - Lorenzo Posani
- Center for Theoretical Neuroscience, Columbia University, New York, NY 10027, USA; Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
| | | | - Steven A Siegelbaum
- Department of Neuroscience, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, NY 10027, USA; Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA; Department of Pharmacology, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, NY 10032, USA; Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA.
| | - Stefano Fusi
- Department of Neuroscience, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, NY 10027, USA; Center for Theoretical Neuroscience, Columbia University, New York, NY 10027, USA; Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA; Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA.
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2
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Whitebirch AC, Santoro B, Barnett A, Lisgaras CP, Scharfman HE, Siegelbaum SA. Reduced Cholecystokinin-Expressing Interneuron Input Contributes to Disinhibition of the Hippocampal CA2 Region in a Mouse Model of Temporal Lobe Epilepsy. J Neurosci 2023; 43:6930-6949. [PMID: 37643861 PMCID: PMC10573827 DOI: 10.1523/jneurosci.2091-22.2023] [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: 11/09/2022] [Revised: 08/04/2023] [Accepted: 08/15/2023] [Indexed: 08/31/2023] Open
Abstract
A significant proportion of temporal lobe epilepsy (TLE) patients experience drug-resistant seizures associated with mesial temporal sclerosis, in which there is extensive cell loss in the hippocampal CA1 and CA3 subfields, with a relative sparing of dentate gyrus granule cells and CA2 pyramidal neurons (PNs). A role for CA2 in seizure generation was suggested based on findings of a reduction in CA2 synaptic inhibition (Williamson and Spencer, 1994) and the presence of interictal-like spike activity in CA2 in resected hippocampal tissue from TLE patients (Wittner et al., 2009). We recently found that in the pilocarpine-induced status epilepticus (PILO-SE) mouse model of TLE there was an increase in CA2 intrinsic excitability associated with a loss of CA2 synaptic inhibition. Furthermore, chemogenetic silencing of CA2 significantly reduced seizure frequency, consistent with a role of CA2 in promoting seizure generation and/or propagation (Whitebirch et al., 2022). In the present study, we explored the cellular basis of this inhibitory deficit using immunohistochemical and electrophysiological approaches in PILO-SE male and female mice. We report a widespread decrease in the density of pro-cholecystokinin-immunopositive (CCK+) interneurons and a functional impairment of CCK+ interneuron-mediated inhibition of CA2 PNs. We also found a disruption in the perisomatic perineuronal net in the CA2 stratum pyramidale. Such pathologic alterations may contribute to an enhanced excitation of CA2 PNs and CA2-dependent seizure activity in the PILO-SE mouse model.SIGNIFICANCE STATEMENT Impaired synaptic inhibition in hippocampal circuits has been identified as a key feature that contributes to the emergence and propagation of seizure activity in human patients and animal models of temporal lobe epilepsy (TLE). Among the hippocampal subfields, the CA2 region is particularly resilient to seizure-associated neurodegeneration and has been suggested to play a key role in seizure activity in TLE. Here we report that perisomatic inhibition of CA2 pyramidal neurons mediated by cholecystokinin-expressing interneurons is selectively reduced in acute hippocampal slices from epileptic mice. Parvalbumin-expressing interneurons, in contrast, appear relatively conserved in epileptic mice. These findings advance our understanding of the cellular mechanisms underlying inhibitory disruption in hippocampal circuits in a mouse model of spontaneous recurring seizures.
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Affiliation(s)
- Alexander C Whitebirch
- Departments of Neuroscience and Pharmacology, Kavli Institute for Brain Science, Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University Irving Medical Center, New York, New York 10027
| | - Bina Santoro
- Departments of Neuroscience and Pharmacology, Kavli Institute for Brain Science, Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University Irving Medical Center, New York, New York 10027
| | - Anastasia Barnett
- Departments of Neuroscience and Pharmacology, Kavli Institute for Brain Science, Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University Irving Medical Center, New York, New York 10027
| | - Christos Panagiotis Lisgaras
- Department of Child & Adolescent Psychiatry, New York University Langone Health, New York, New York 10016
- Department of Neuroscience & Physiology, New York University Langone Health, New York, New York 10016
- Department of Psychiatry, New York University Langone Health, New York, New York 10016
- The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, New York 10962
| | - Helen E Scharfman
- Department of Child & Adolescent Psychiatry, New York University Langone Health, New York, New York 10016
- Department of Neuroscience & Physiology, New York University Langone Health, New York, New York 10016
- Department of Psychiatry, New York University Langone Health, New York, New York 10016
- The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, New York 10962
| | - Steven A Siegelbaum
- Departments of Neuroscience and Pharmacology, Kavli Institute for Brain Science, Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University Irving Medical Center, New York, New York 10027
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3
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Milstein AD, Tran S, Ng G, Soltesz I. Offline memory replay in recurrent neuronal networks emerges from constraints on online dynamics. J Physiol 2023; 601:3241-3264. [PMID: 35907087 PMCID: PMC9885000 DOI: 10.1113/jp283216] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 07/22/2022] [Indexed: 02/01/2023] Open
Abstract
During spatial exploration, neural circuits in the hippocampus store memories of sequences of sensory events encountered in the environment. When sensory information is absent during 'offline' resting periods, brief neuronal population bursts can 'replay' sequences of activity that resemble bouts of sensory experience. These sequences can occur in either forward or reverse order, and can even include spatial trajectories that have not been experienced, but are consistent with the topology of the environment. The neural circuit mechanisms underlying this variable and flexible sequence generation are unknown. Here we demonstrate in a recurrent spiking network model of hippocampal area CA3 that experimental constraints on network dynamics such as population sparsity, stimulus selectivity, rhythmicity and spike rate adaptation, as well as associative synaptic connectivity, enable additional emergent properties, including variable offline memory replay. In an online stimulus-driven state, we observed the emergence of neuronal sequences that swept from representations of past to future stimuli on the timescale of the theta rhythm. In an offline state driven only by noise, the network generated both forward and reverse neuronal sequences, and recapitulated the experimental observation that offline memory replay events tend to include salient locations like the site of a reward. These results demonstrate that biological constraints on the dynamics of recurrent neural circuits are sufficient to enable memories of sensory events stored in the strengths of synaptic connections to be flexibly read out during rest and sleep, which is thought to be important for memory consolidation and planning of future behaviour. KEY POINTS: A recurrent spiking network model of hippocampal area CA3 was optimized to recapitulate experimentally observed network dynamics during simulated spatial exploration. During simulated offline rest, the network exhibited the emergent property of generating flexible forward, reverse and mixed direction memory replay events. Network perturbations and analysis of model diversity and degeneracy identified associative synaptic connectivity and key features of network dynamics as important for offline sequence generation. Network simulations demonstrate that population over-representation of salient positions like the site of reward results in biased memory replay.
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Affiliation(s)
- Aaron D. Milstein
- Department of Neurosurgery, Stanford University School of Medicine, Stanford CA
- Department of Neuroscience and Cell Biology, Robert Wood Johnson Medical School and Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, NJ
| | - Sarah Tran
- Department of Neurosurgery, Stanford University School of Medicine, Stanford CA
| | - Grace Ng
- Department of Neurosurgery, Stanford University School of Medicine, Stanford CA
| | - Ivan Soltesz
- Department of Neurosurgery, Stanford University School of Medicine, Stanford CA
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4
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Diethorn EJ, Gould E. Development of the hippocampal CA2 region and the emergence of social recognition. Dev Neurobiol 2023; 83:143-156. [PMID: 37326250 PMCID: PMC10529477 DOI: 10.1002/dneu.22919] [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: 02/20/2023] [Revised: 05/08/2023] [Accepted: 05/29/2023] [Indexed: 06/17/2023]
Abstract
Social memories formed in early life, like those for family and unrelated peers, are known to contribute to healthy social interactions throughout life, although how the developing brain supports social memory remains relatively unexplored. The CA2 subregion of the hippocampus is involved in social memory function, but most literature on this subject is restricted to studies of adult rodents. Here, we review the current literature on the embryonic and postnatal development of hippocampal subregion CA2 in mammals, with a focus on the emergence of its unusual molecular and cellular characteristics, including its notably high expression of plasticity-suppressing molecules. We also consider the connectivity of the CA2 with other brain areas, including intrahippocampal regions, such as the dentate gyrus, CA3, and CA1 regions, and extrahippocampal regions, such as the hypothalamus, ventral tegmental area, basal forebrain, raphe nuclei, and the entorhinal cortex. We review developmental milestones of CA2 molecular, cellular, and circuit-level features that may contribute to emerging social recognition abilities for kin and unrelated conspecifics in early life. Lastly, we consider genetic mouse models related to neurodevelopmental disorders in humans in order to survey evidence about whether atypical formation of the CA2 may contribute to social memory dysfunction.
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Affiliation(s)
- Emma J Diethorn
- Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey, USA
| | - Elizabeth Gould
- Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey, USA
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5
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Zhou Z, Norimoto H. Sleep sharp wave ripple and its functions in memory and synaptic plasticity. Neurosci Res 2023; 189:20-28. [PMID: 37045494 DOI: 10.1016/j.neures.2023.01.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 12/12/2022] [Accepted: 12/16/2022] [Indexed: 04/14/2023]
Abstract
Memory is one of the fundamental cognitive functions of brain. The formation and consolidation of memory depend on the hippocampus and sleep. Sharp wave ripple (SWR) is an electrophysiological event which is most frequently observed in the hippocampus during sleep. It represents a highly synchronized neuronal activity pattern which modulates numerous brain regions including the neocortex, subcortical areas, and the hippocampus itself. In this review, we discuss how SWRs link experiences to memories and what happens in the hippocampus and other brain regions during sleep by focusing on synaptic plasticity.
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Affiliation(s)
- Zhiwen Zhou
- Graduate School of Medicine, Hokkaido University, West 7 North 15 Kita-ku, Sapporo, Hokkaido 060-8638, Japan.
| | - Hiroaki Norimoto
- Graduate School of Medicine, Hokkaido University, West 7 North 15 Kita-ku, Sapporo, Hokkaido 060-8638, Japan.
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6
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Oliva A, Fernandez-Ruiz A, Karaba LA. CA2 orchestrates hippocampal network dynamics. Hippocampus 2023; 33:241-251. [PMID: 36575880 PMCID: PMC9974898 DOI: 10.1002/hipo.23495] [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: 08/02/2022] [Revised: 11/25/2022] [Accepted: 12/11/2022] [Indexed: 12/29/2022]
Abstract
The hippocampus is composed of various subregions: CA1, CA2, CA3, and the dentate gyrus (DG). Despite the abundant hippocampal research literature, until recently, CA2 received little attention. The development of new genetic and physiological tools allowed recent studies characterizing the unique properties and functional roles of this hippocampal subregion. Despite its small size, the cellular content of CA2 is heterogeneous at the molecular and physiological levels. CA2 has been heavily implicated in social behaviors, including social memory. More generally, the mechanisms by which the hippocampus is involved in memory include the reactivation of neuronal ensembles following experience. This process is coordinated by synchronous network events known as sharp-wave ripples (SWRs). Recent evidence suggests that CA2 plays an important role in the generation of SWRs. The unique connectivity and physiological properties of CA2 pyramidal cells make this region a computational hub at the core of hippocampal information processing. Here, we review recent findings that support the role of CA2 in coordinating hippocampal network dynamics from a systems neuroscience perspective.
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Affiliation(s)
- Azahara Oliva
- Department of Neurobiology and Behavior, Cornell University, Ithaca, New York, USA
| | | | - Lindsay A Karaba
- Department of Neurobiology and Behavior, Cornell University, Ithaca, New York, USA
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7
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Chevaleyre V, Piskorowski R. New hues for CA2. Hippocampus 2023; 33:161-165. [PMID: 36585825 DOI: 10.1002/hipo.23496] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 12/10/2022] [Accepted: 12/16/2022] [Indexed: 01/01/2023]
Affiliation(s)
- Vivien Chevaleyre
- INSERM U1266, Institute of Psychiatry and Neuroscience of Paris (IPNP), Université Paris Cité, Paris, France.,GHU Paris Psychiatrie et Neurosciences, Hôpital Sainte Anne, Paris, France
| | - Rebecca Piskorowski
- INSERM U1266, Institute of Psychiatry and Neuroscience of Paris (IPNP), Université Paris Cité, Paris, France.,GHU Paris Psychiatrie et Neurosciences, Hôpital Sainte Anne, Paris, France
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8
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Kilias A, Tulke S, Barheier N, Ruther P, Häussler U. Integration of the CA2 region in the hippocampal network during epileptogenesis. Hippocampus 2023; 33:223-240. [PMID: 36421040 DOI: 10.1002/hipo.23479] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 10/14/2022] [Accepted: 11/02/2022] [Indexed: 11/26/2022]
Abstract
The CA2 pyramidal cells are mostly resistant to cell death in mesial temporal lobe epilepsy (MTLE) with hippocampal sclerosis, but they are aberrantly integrated into the epileptic hippocampal network via mossy fiber sprouting. Furthermore, they show increased excitability in vitro in hippocampal slices obtained from human MTLE specimens or animal epilepsy models. Although these changes promote CA2 to contribute to epileptic activity (EA) in vivo, the role of CA2 in the epileptic network within and beyond the sclerotic hippocampus is still unclear. We used the intrahippocampal kainate mouse model for MTLE, which recapitulates most features of the human disease including pharmacoresistant epileptic seizures and hippocampal sclerosis, with preservation of dentate gyrus (DG) granule cells and CA2 pyramidal cells. In vivo recordings with electrodes in CA2 and the DG showed that EA occurs at high coincidence between the ipsilateral DG and CA2 and current source density analysis of silicon probe recordings in dorsal ipsilateral CA2 revealed CA2 as a local source of EA. Cell-specific viral tracing in Amigo2-icreERT2 mice confirmed the preservation of the axonal projection from ipsilateral CA2 pyramidal cells to contralateral CA2 under epileptic conditions and indeed, EA propagated from ipsi- to contralateral CA2 with increasing likelihood with time after KA injection, but always at lower intensity than within the ipsilateral hippocampus. Furthermore, we show that CA2 presents with local theta oscillations and like the DG, shows a pathological reduction of theta frequency already from 2 days after KA onward. The early changes in activity might be facilitated by the loss of glutamic acid decarboxylase 67 (Gad67) mRNA-expressing interneurons directly after the initial status epilepticus in ipsi- but not contralateral CA2. Together, our data highlight CA2 as an active player in the epileptic network and with its contralateral connections as one possible router of aberrant activity.
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Affiliation(s)
- Antje Kilias
- Institute for Physiology I, Medical Faculty, University of Freiburg, Freiburg, Germany
| | - Susanne Tulke
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany
| | - Nicole Barheier
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Patrick Ruther
- Microsystem Materials Laboratory, Department of Microsystems Engineering (IMTEK), University of Freiburg, Freiburg, Germany.,Center BrainLinks-BrainTools, University of Freiburg, Freiburg, Germany
| | - Ute Häussler
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.,Center BrainLinks-BrainTools, University of Freiburg, Freiburg, Germany
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9
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Bienkowski MS. Further refining the boundaries of the hippocampus CA2 with gene expression and connectivity: Potential subregions and heterogeneous cell types. Hippocampus 2023; 33:150-160. [PMID: 36786207 PMCID: PMC9987718 DOI: 10.1002/hipo.23508] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 01/20/2023] [Accepted: 01/23/2023] [Indexed: 02/15/2023]
Abstract
Over the last two decades, the definition of hippocampal area CA2 has evolved from Lorente de Nó's original Golgi-based morphological description with the discovery of specific CA2 gene expression markers. Exploiting the specificity of these molecules has allowed for the genetic dissection of CA2 structure and function in transgenic mice. With this change in criteria, the anatomical boundaries of the CA2 have expanded across the hippocampal axis but the CA2's full rostrocaudal extent is not consistently delineated across atlases. The Hippocampus Gene Expression Atlas (HGEA) provides a comprehensive map of 20 gene expression domains across the entire mouse hippocampus including the CA2. In this commentary, I will review the consensus gene expression patterns that demarcate the expanded CA2 boundaries in the HGEA. Using DropViz single-cell transcriptomics and Mouse Connectome Project connectomics data, I will then suggest potential differences in CA2 cell type heterogeneity and connectivity that may identify and characterize further CA2 subregions.
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Affiliation(s)
- Michael S Bienkowski
- USC Mark and Mary Stevens Neuroimaging and Informatics Institute, Keck School of Medicine of USC, University of Southern California, Los Angeles, California, USA
- Zilkha Neurogenetic Institute, Keck School of Medicine of University of Southern California, Los Angeles, California, USA
- USC Center for Integrative Connectomics, Keck School of Medicine of University of Southern California, Los Angeles, CA, USA
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10
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Shinohara Y, Kohara K. Projections of hippocampal CA2 pyramidal neurons: Distinct innervation patterns of CA2 compared to CA3 in rodents. Hippocampus 2023; 33:691-699. [PMID: 36855258 DOI: 10.1002/hipo.23519] [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: 09/01/2022] [Revised: 02/01/2023] [Accepted: 02/14/2023] [Indexed: 03/02/2023]
Abstract
The hippocampus is a center for spatial and episodic memory formation in rodents. Understanding the composition of subregions and circuitry maps of the hippocampus is essential for elucidating the mechanism of memory formation and recall. For decades, the trisynaptic circuit (entorhinal cortex layer II-dentate gyrus - CA3-CA1) has been considered the neural network substrate responsible for learning and memory. Recently, CA2 has emerged as an important area in the hippocampal circuitry, with distinct functions from those of CA3. In this article, we review the historical definition of the hippocampal area CA2 and the differential projection patterns between CA2 and CA3 pyramidal neurons. We provide a concise and comprehensive map of CA2 outputs by comparing (1) ipsi versus contra projections, (2) septal versus temporal projections, and (3) lamellar structures of CA2 and CA3 pyramidal neurons.
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Affiliation(s)
- Yoshiaki Shinohara
- Department of Anatomy and Cell Biology, Faculty of Medicine, University of Yamanashi, Chuo, Yamanashi, Japan
| | - Keigo Kohara
- KMU Biobank Center, Institute of Biomedical Science, Kansai Medical University, Hirakata, Osaka, Japan
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11
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Okamoto K, Kamikubo Y, Yamauchi K, Okamoto S, Takahashi M, Ishida Y, Koike M, Ikegaya Y, Sakurai T, Hioki H. Specific AAV2/PHP.eB-mediated gene transduction of CA2 pyramidal cells via injection into the lateral ventricle. Sci Rep 2023; 13:323. [PMID: 36609635 PMCID: PMC9822962 DOI: 10.1038/s41598-022-27372-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 12/30/2022] [Indexed: 01/09/2023] Open
Abstract
Given its limited accessibility, the CA2 area has been less investigated compared to other subregions of the hippocampus. While the development of transgenic mice expressing Cre recombinase in the CA2 has revealed unique features of this area, the use of mouse lines has several limitations, such as lack of specificity. Therefore, a specific gene delivery system is required. Here, we confirmed that the AAV-PHP.eB capsid preferably infected CA2 pyramidal cells following retro-orbital injection and demonstrated that the specificity was substantially higher after injection into the lateral ventricle. In addition, a tropism for the CA2 area was observed in organotypic slice cultures. Combined injection into the lateral ventricle and stereotaxic injection into the CA2 area specifically introduced the transgene into CA2 pyramidal cells, enabling us to perform targeted patch-clamp recordings and optogenetic manipulation. These results suggest that AAV-PHP.eB is a versatile tool for specific gene transduction in CA2 pyramidal cells.
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Affiliation(s)
- Kazuki Okamoto
- grid.258269.20000 0004 1762 2738Department of Neuroanatomy, Juntendo University Graduate School of Medicine, Bunkyo-Ku, Tokyo, 113-8421 Japan ,grid.258269.20000 0004 1762 2738Department of Cell Biology and Neuroscience, Juntendo University Graduate School of Medicine, Bunkyo-Ku, Tokyo, 113-8421 Japan ,grid.258269.20000 0004 1762 2738Juntendo Advanced Research Institute for Health Science, Juntendo University, Bunkyo-Ku, Tokyo, 113-8421 Japan
| | - Yuji Kamikubo
- grid.258269.20000 0004 1762 2738Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-Ku, Tokyo, 113-8421 Japan
| | - Kenta Yamauchi
- grid.258269.20000 0004 1762 2738Department of Neuroanatomy, Juntendo University Graduate School of Medicine, Bunkyo-Ku, Tokyo, 113-8421 Japan ,grid.258269.20000 0004 1762 2738Department of Cell Biology and Neuroscience, Juntendo University Graduate School of Medicine, Bunkyo-Ku, Tokyo, 113-8421 Japan ,grid.258269.20000 0004 1762 2738Juntendo Advanced Research Institute for Health Science, Juntendo University, Bunkyo-Ku, Tokyo, 113-8421 Japan
| | - Shinichiro Okamoto
- grid.258269.20000 0004 1762 2738Department of Neuroanatomy, Juntendo University Graduate School of Medicine, Bunkyo-Ku, Tokyo, 113-8421 Japan ,grid.258269.20000 0004 1762 2738Department of Cell Biology and Neuroscience, Juntendo University Graduate School of Medicine, Bunkyo-Ku, Tokyo, 113-8421 Japan ,grid.258269.20000 0004 1762 2738Juntendo Advanced Research Institute for Health Science, Juntendo University, Bunkyo-Ku, Tokyo, 113-8421 Japan
| | - Megumu Takahashi
- grid.258269.20000 0004 1762 2738Department of Neuroanatomy, Juntendo University Graduate School of Medicine, Bunkyo-Ku, Tokyo, 113-8421 Japan ,grid.258269.20000 0004 1762 2738Department of Cell Biology and Neuroscience, Juntendo University Graduate School of Medicine, Bunkyo-Ku, Tokyo, 113-8421 Japan ,grid.258799.80000 0004 0372 2033Department of Neuroscience, Graduate School of Medicine, Kyoto University, Kyoto, Kyoto 606-8501 Japan ,grid.54432.340000 0001 0860 6072Research Fellow of Japan Society for the Promotion of Science (JSPS), Chiyoda-ku, Tokyo, 102-0083 Japan
| | - Yoko Ishida
- grid.258269.20000 0004 1762 2738Department of Neuroanatomy, Juntendo University Graduate School of Medicine, Bunkyo-Ku, Tokyo, 113-8421 Japan ,grid.258269.20000 0004 1762 2738Department of Cell Biology and Neuroscience, Juntendo University Graduate School of Medicine, Bunkyo-Ku, Tokyo, 113-8421 Japan ,grid.258269.20000 0004 1762 2738Juntendo Advanced Research Institute for Health Science, Juntendo University, Bunkyo-Ku, Tokyo, 113-8421 Japan
| | - Masato Koike
- grid.258269.20000 0004 1762 2738Department of Cell Biology and Neuroscience, Juntendo University Graduate School of Medicine, Bunkyo-Ku, Tokyo, 113-8421 Japan ,grid.258269.20000 0004 1762 2738Juntendo Advanced Research Institute for Health Science, Juntendo University, Bunkyo-Ku, Tokyo, 113-8421 Japan
| | - Yuji Ikegaya
- grid.26999.3d0000 0001 2151 536XLaboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo‐ku, Tokyo, 113‐0033 Japan ,grid.28312.3a0000 0001 0590 0962Center for Information and Neural Networks, National Institute of Information and Communications Technology, Suita, Osaka 565-0871 Japan ,grid.26999.3d0000 0001 2151 536XInstitute for AI and Beyond, The University of Tokyo, Bunkyo‐ku, Tokyo, 113‐0033 Japan
| | - Takashi Sakurai
- grid.258269.20000 0004 1762 2738Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-Ku, Tokyo, 113-8421 Japan
| | - Hiroyuki Hioki
- Department of Neuroanatomy, Juntendo University Graduate School of Medicine, Bunkyo-Ku, Tokyo, 113-8421, Japan. .,Department of Cell Biology and Neuroscience, Juntendo University Graduate School of Medicine, Bunkyo-Ku, Tokyo, 113-8421, Japan. .,Department of Multi-Scale Brain Structure Imaging, Juntendo University Graduate School of Medicine, Bunkyo-Ku, Tokyo, 113-8421, Japan.
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12
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Whitebirch AC, LaFrancois JJ, Jain S, Leary P, Santoro B, Siegelbaum SA, Scharfman HE. Enhanced excitability of the hippocampal CA2 region and its contribution to seizure activity in a mouse model of temporal lobe epilepsy. Neuron 2022; 110:3121-3138.e8. [PMID: 35987207 PMCID: PMC9547935 DOI: 10.1016/j.neuron.2022.07.020] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 05/26/2022] [Accepted: 07/19/2022] [Indexed: 11/25/2022]
Abstract
The hippocampal CA2 region, an area important for social memory, has been suspected to play a role in temporal lobe epilepsy (TLE) because of its resistance to degeneration observed in neighboring CA1 and CA3 regions in both humans and rodent models of TLE. However, little is known about whether alterations in CA2 properties promote seizure generation or propagation. Here, we addressed the role of CA2 using the pilocarpine-induced status epilepticus model of TLE. Ex vivo electrophysiological recordings from acute hippocampal slices revealed a set of coordinated changes that enhance CA2 PC intrinsic excitability, reduce CA2 inhibitory input, and increase CA2 excitatory output to its major CA1 synaptic target. Moreover, selective chemogenetic silencing of CA2 pyramidal cells caused a significant decrease in the frequency of spontaneous seizures measured in vivo. These findings provide the first evidence that CA2 actively contributes to TLE seizure activity and may thus be a promising therapeutic target.
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Affiliation(s)
- Alexander C Whitebirch
- Departments of Neuroscience and Pharmacology, Kavli Institute for Brain Science, Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University Irving Medical Center, New York, NY 10027, USA
| | - John J LaFrancois
- The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA
| | - Swati Jain
- The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA
| | - Paige Leary
- Department of Neuroscience and Physiology, New York University Langone Health, New York, NY 10016, USA
| | - Bina Santoro
- Departments of Neuroscience and Pharmacology, Kavli Institute for Brain Science, Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University Irving Medical Center, New York, NY 10027, USA
| | - Steven A Siegelbaum
- Departments of Neuroscience and Pharmacology, Kavli Institute for Brain Science, Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University Irving Medical Center, New York, NY 10027, USA.
| | - Helen E Scharfman
- Department of Child Psychiatry, New York University Langone Health, New York, NY 10016, USA; Department of Neuroscience and Physiology, New York University Langone Health, New York, NY 10016, USA; Department of Psychiatry, New York University Langone Health, New York, NY 10016, USA; The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA.
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13
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Soldatkina O, Schönsberg F, Treves A. Challenges for Place and Grid Cell Models. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1359:285-312. [DOI: 10.1007/978-3-030-89439-9_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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14
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Abstract
Astrocytes play a key role in brain homeostasis and functions such as memory. Specifically, astrocytes express multiple receptors that transduce signals via the second messenger cAMP. However, the involvement of astrocytic cAMP in animal behavior and the underlying glial-neuronal interactions remains largely unknown. Here, we show that an increase in astrocytic cAMP is sufficient to induce synaptic plasticity and modulate memory. We developed a method to increase astrocytic cAMP levels in vivo using photoactivated adenylyl cyclase and found that increased cAMP in hippocampal astrocytes at different time points facilitated memory formation but interrupted memory retention via NMDA receptor-dependent plasticity. Furthermore, we found that the cAMP-induced modulation of memory was mediated by the astrocyte-neuron lactate shuttle. Thus, our study unveils a role of astrocytic cAMP in brain function by providing a tool to modulate astrocytic cAMP in vivo.
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15
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Lehr AB, Kumar A, Tetzlaff C, Hafting T, Fyhn M, Stöber TM. CA2 beyond social memory: Evidence for a fundamental role in hippocampal information processing. Neurosci Biobehav Rev 2021; 126:398-412. [PMID: 33775693 DOI: 10.1016/j.neubiorev.2021.03.020] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 03/16/2021] [Accepted: 03/18/2021] [Indexed: 01/16/2023]
Abstract
Hippocampal region CA2 has received increased attention due to its importance in social recognition memory. While its specific function remains to be identified, there are indications that CA2 plays a major role in a variety of situations, widely extending beyond social memory. In this targeted review, we highlight lines of research which have begun to converge on a more fundamental role for CA2 in hippocampus-dependent memory processing. We discuss recent proposals that speak to the computations CA2 may perform within the hippocampal circuit.
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Affiliation(s)
- Andrew B Lehr
- Department of Computational Neuroscience, University of Göttingen, Germany; Bernstein Center for Computational Neuroscience, University of Göttingen, Germany; Department of Computational Physiology, Simula Research Laboratory, Lysaker, Norway; Centre for Integrative Neuroplasticity, University of Oslo, Norway.
| | - Arvind Kumar
- Department of Computational Science and Technology, KTH Royal Institute of Technology, Sweden
| | - Christian Tetzlaff
- Department of Computational Neuroscience, University of Göttingen, Germany; Bernstein Center for Computational Neuroscience, University of Göttingen, Germany
| | - Torkel Hafting
- Centre for Integrative Neuroplasticity, University of Oslo, Norway; Institute of Basic Medical Sciences, University of Oslo, Norway
| | - Marianne Fyhn
- Centre for Integrative Neuroplasticity, University of Oslo, Norway; Department of Biosciences, University of Oslo, Norway
| | - Tristan M Stöber
- Department of Computational Physiology, Simula Research Laboratory, Lysaker, Norway; Centre for Integrative Neuroplasticity, University of Oslo, Norway; Department of Informatics, University of Oslo, Norway.
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16
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Stöber TM, Lehr AB, Hafting T, Kumar A, Fyhn M. Selective neuromodulation and mutual inhibition within the
CA3–CA2
system can prioritize sequences for replay. Hippocampus 2020; 30:1228-1238. [DOI: 10.1002/hipo.23256] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 07/10/2020] [Accepted: 08/07/2020] [Indexed: 11/06/2022]
Affiliation(s)
- Tristan M. Stöber
- Department of Computational Physiology Simula Research Laboratory Lysaker Norway
- Centre for Integrative Neuroplasticity University of Oslo Oslo Norway
- Department of Informatics University of Oslo Oslo Norway
| | - Andrew B. Lehr
- Department of Computational Physiology Simula Research Laboratory Lysaker Norway
- Centre for Integrative Neuroplasticity University of Oslo Oslo Norway
- Department of Computational Neuroscience University of Göttingen Göttingen Germany
| | - Torkel Hafting
- Centre for Integrative Neuroplasticity University of Oslo Oslo Norway
- Institute of Basic Medical Sciences University of Oslo Oslo Norway
| | - Arvind Kumar
- Department of Computational Science and Technology KTH Royal Institute of Technology Stockholm Sweden
| | - Marianne Fyhn
- Centre for Integrative Neuroplasticity University of Oslo Oslo Norway
- Department of Biosciences University of Oslo Oslo Norway
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17
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de la Prida LM. Potential factors influencing replay across CA1 during sharp-wave ripples. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190236. [PMID: 32248778 DOI: 10.1098/rstb.2019.0236] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Sharp-wave ripples are complex neurophysiological events recorded along the trisynaptic hippocampal circuit (i.e. from CA3 to CA1 and the subiculum) during slow-wave sleep and awake states. They arise locally but scale brain-wide to the hippocampal target regions at cortical and subcortical structures. During these events, neuronal firing sequences are replayed retrospectively or prospectively and in the forward or reverse order as defined by experience. They could reflect either pre-configured firing sequences, learned sequences or an option space to inform subsequent decisions. How can different sequences arise during sharp-wave ripples? Emerging data suggest the hippocampal circuit is organized in different loops across the proximal (close to dentate gyrus) and distal (close to entorhinal cortex) axis. These data also disclose a so-far neglected laminar organization of the hippocampal output during sharp-wave events. Here, I discuss whether by incorporating cell-type-specific mechanisms converging on deep and superficial CA1 sublayers along the proximodistal axis, some novel factors influencing the organization of hippocampal sequences could be unveiled. This article is part of the Theo Murphy meeting issue 'Memory reactivation: replaying events past, present and future'.
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Abstract
Although Lorente de No' recognized the anatomical distinction of the hippocampal Cornu Ammonis (CA) 2 region, it had, until recently, been assigned no unique function. Its location between the key players of the circuit, CA3 and CA1, which along with the entorhinal cortex and dentate gyrus compose the classic trisynaptic circuit, further distracted research interest. However, the connectivity of CA2 pyramidal cells, together with unique patterns of gene expression, hints at a much larger contribution to hippocampal information processing than has been ascribed. Here we review recent advances that have identified new roles for CA2 in hippocampal centric processing, together with specialized functions in social memory and, potentially, as a broadcaster of novelty. These new data, together with CA2's role in disease, justify a closer look at how this small region exerts its influence and how it might best be exploited to understand and treat disease-related circuit dysfunctions.
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Affiliation(s)
- Steven J Middleton
- Laboratory for Circuit and Behavioral Physiology, RIKEN Center for Brain Science, Wako-shi, Saitama 351-0198, Japan; ,
| | - Thomas J McHugh
- Laboratory for Circuit and Behavioral Physiology, RIKEN Center for Brain Science, Wako-shi, Saitama 351-0198, Japan; ,
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