1
|
Raghuraman R, Navakkode S, Sajikumar S. Alteration of hippocampal CA2 plasticity and social memory in adult rats impacted by juvenile stress. Hippocampus 2023; 33:745-758. [PMID: 36965045 PMCID: PMC10946601 DOI: 10.1002/hipo.23531] [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: 06/15/2022] [Revised: 03/09/2023] [Accepted: 03/11/2023] [Indexed: 03/27/2023]
Abstract
The hippocampal CA2 region has received greater attention in recent years due to its fundamental role in social memory and hippocampus-dependent memory processing. Unlike entorhinal cortical inputs, the Schaffer collateral inputs to CA2 do not support activity-dependent long-term potentiation (LTP), which serves as the basis for long-term memories. This LTP-resistant zone also expresses genes that restrict plasticity. With the aim of exploring social interaction and sociability in rats that were subjected to juvenile stress, we addressed questions about how the neural circuitry is altered and its effects on social behavior. Although there was induction of LTP in both Schaffer collateral and entorhinal cortical pathways in juvenile-stressed rats, LTP declined in both pathways after 2-3 h. Moreover, exogenous bath application of substance P, a neuropeptide that resulted in slow onset long-lasting potentiation in control animals while it failed to induce LTP in juvenile-stressed rats. Our study reveals that juvenile-stressed rats show behavioral and cellular abnormalities with a long-lasting impact in adulthood.
Collapse
Affiliation(s)
- Radha Raghuraman
- Department of PhysiologyNational University of SingaporeSingapore117593Singapore
- Life Sciences Institute Neurobiology ProgrammeCentre for Life Sciences, National University of SingaporeSingapore117456Singapore
- Present address:
Taub Institute for Research on Alzheimer's Disease and the Aging BrainColumbia University Irving Medical CenterNew YorkNew York10032USA
| | - Sheeja Navakkode
- Lee Kong Chian School of MedicineNanyang Technological UniversitySingapore308232Singapore
| | - Sreedharan Sajikumar
- Department of PhysiologyNational University of SingaporeSingapore117593Singapore
- Life Sciences Institute Neurobiology ProgrammeCentre for Life Sciences, National University of SingaporeSingapore117456Singapore
- Healthy Longevity Translational Research ProgrammeYong Loo Lin School of Medicine, National University of SingaporeSingapore117456Singapore
| |
Collapse
|
2
|
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.
Collapse
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
| |
Collapse
|
3
|
Loisy M, Farah A, Fafouri A, Fanton A, Ahmadi M, Therreau L, Chevaleyre V, Piskorowski RA. Environmental enrichment and social isolation modulate inhibitory transmission and plasticity in hippocampal area CA2. Hippocampus 2023; 33:197-207. [PMID: 36374115 DOI: 10.1002/hipo.23478] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 10/03/2022] [Accepted: 10/26/2022] [Indexed: 11/16/2022]
Abstract
Environmental factors are well-accepted to play a complex and interdependent role with genetic factors in learning and memory. The goal of this study was to examine how environmental conditions altered synaptic plasticity in hippocampal area CA2. To do this, we housed adult mice for 3 weeks in an enriched environment (EE) consisting of a larger cage with running wheel, and regularly changed toys, tunnels and treats. We then performed whole-cell or extracellular field recordings in hippocampal area CA2 and compared the synaptic plasticity from EE-housed mice with slices from littermate controls housed in standard environment (SE). We found that the inhibitory transmission recruited by CA3 input stimulation in CA2 was significantly less plastic in EE conditions as compared to SE following an electrical tetanus. We demonstrate that delta-opioid receptor (DOR) mediated plasticity is reduced in EE conditions by direct application of DOR agonist. We show that in EE conditions the overall levels of GABA transmission is reduced in CA2 cells by analyzing inhibition of ErbB4 receptor, spontaneous inhibitory currents and paired-pulse ratio. Furthermore, we report that the effect of EE of synaptic plasticity can be rapidly reversed by social isolation. These results demonstrate how the neurons in hippocampal area CA2 are sensitive to environment and may lead to promising therapeutic targets.
Collapse
Affiliation(s)
- Maïthé Loisy
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM U1266, Paris, France
| | - Amel Farah
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM U1266, Paris, France
| | - Assia Fafouri
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM U1266, Paris, France
| | - Aurélien Fanton
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM U1266, Paris, France
| | - Mahboubeh Ahmadi
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM U1266, Paris, France
| | - Ludivine Therreau
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM U1266, Paris, France
| | - Vivien Chevaleyre
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM U1266, Paris, France.,GHU Paris Psychiatrie et Neurosciences, Hôpital Sainte Anne, Paris, France
| | - Rebecca A Piskorowski
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM U1266, Paris, France.,GHU Paris Psychiatrie et Neurosciences, Hôpital Sainte Anne, Paris, France
| |
Collapse
|
4
|
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.
Collapse
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
| |
Collapse
|
5
|
Piskorowski RA, Chevaleyre V. Hippocampal area CA2: interneuron disfunction during pathological states. Front Neural Circuits 2023; 17:1181032. [PMID: 37180763 PMCID: PMC10174260 DOI: 10.3389/fncir.2023.1181032] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 04/07/2023] [Indexed: 05/16/2023] Open
Abstract
Hippocampal area CA2 plays a critical role in social recognition memory and has unique cellular and molecular properties that distinguish it from areas CA1 and CA3. In addition to having a particularly high density of interneurons, the inhibitory transmission in this region displays two distinct forms of long-term synaptic plasticity. Early studies on human hippocampal tissue have reported unique alteration in area CA2 with several pathologies and psychiatric disorders. In this review, we present recent studies revealing changes in inhibitory transmission and plasticity of area CA2 in mouse models of multiple sclerosis, autism spectrum disorder, Alzheimer's disease, schizophrenia and the 22q11.2 deletion syndrome and propose how these changes could underly deficits in social cognition observed during these pathologies.
Collapse
Affiliation(s)
- Rebecca A. Piskorowski
- Université Paris Cité, INSERM UMRS 1266, Institute of Psychiatry and Neuroscience of Paris, GHU Paris Psychiatrie et Neurosciences, Paris, France
- Institute of Biology Paris Seine, Neuroscience Paris Seine, CNRS UMR 8246, INSERM U1130, Sorbonne Université, Paris, France
- *Correspondence: Rebecca A. Piskorowski,
| | - Vivien Chevaleyre
- Université Paris Cité, INSERM UMRS 1266, Institute of Psychiatry and Neuroscience of Paris, GHU Paris Psychiatrie et Neurosciences, Paris, France
- Institute of Biology Paris Seine, Neuroscience Paris Seine, CNRS UMR 8246, INSERM U1130, Sorbonne Université, Paris, France
| |
Collapse
|
6
|
Oliva A. CA2 physiology underlying social memory. Curr Opin Neurobiol 2022; 77:102642. [PMID: 36215845 DOI: 10.1016/j.conb.2022.102642] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 08/23/2022] [Accepted: 09/11/2022] [Indexed: 01/10/2023]
Abstract
In recent years, convergent evidence has emerged in support of the idea of social brain networks, specific brain regions that are interconnected and support social behaviors. One of these regions is the CA2 area of the hippocampus, a small region strongly connected with cortical and subcortical areas implicated in social behaviors. Furthermore, CA2 area is enriched in receptors for several neuromodulators that are related to various aspects of social behaviors, suggesting that this area could be a key component of social information processing in the brain. In this review, recent findings related to the physiological mechanisms underlying the role of CA2 in social memory are discussed.
Collapse
Affiliation(s)
- Azahara Oliva
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, 14853, USA.
| |
Collapse
|
7
|
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.
Collapse
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.
| |
Collapse
|
8
|
Loisy M, Bouisset G, Lopez S, Muller M, Spitsyn A, Duval J, Piskorowski RA, Verret L, Chevaleyre V. Sequential inhibitory plasticities in hippocampal area CA2 and social memory formation. Neuron 2022; 110:2854-2866.e4. [PMID: 35858622 DOI: 10.1016/j.neuron.2022.06.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 04/22/2022] [Accepted: 06/10/2022] [Indexed: 11/25/2022]
Abstract
Area CA2 is a critical region for diverse hippocampal functions including social recognition memory. This region has unique properties and connectivity. Notably, intra-hippocampal excitatory inputs to CA2 lack canonical long-term plasticity, but inhibitory transmission expresses a long-term depression mediated by Delta-opioid receptors (DOR-iLTDs). Evidence indicates that DOR-iLTDs are insufficient to underlie social coding. Here, we report a novel inhibitory plasticity mediated by cannabinoid type 1 receptor activation (CB1R-iLTD). Surprisingly, CB1R-iLTD requires previous induction of DOR-iLTDs, indicating a permissive role for DOR plasticity. Blockade of CB1Rs in CA2 completely prevents social memory formation. Furthermore, the sequentiality of DOR- and CB1R-mediated plasticity occurs in vivo during successive social interactions. Finally, CB1R-iLTD is altered in a mouse model of schizophrenia with impaired social cognition but is rescued by a manipulation that also rescues social memory. Altogether, our data reveal a unique interplay between two inhibitory plasticities and a novel mechanism for social memory formation.
Collapse
Affiliation(s)
- Maïthé Loisy
- Université Paris Cité, INSERM U1266, Institute of Psychiatry and Neuroscience of Paris, 75014 Paris, France
| | - Guillaume Bouisset
- Research Center on Animal Cognition, Center for Integrative Biology, Toulouse University, CNRS, UPS, 31062 Toulouse, France
| | - Sébastien Lopez
- Research Center on Animal Cognition, Center for Integrative Biology, Toulouse University, CNRS, UPS, 31062 Toulouse, France
| | - Maud Muller
- Université Paris Cité, INSERM U1266, Institute of Psychiatry and Neuroscience of Paris, 75014 Paris, France
| | - Alena Spitsyn
- Université Paris Cité, INSERM U1266, Institute of Psychiatry and Neuroscience of Paris, 75014 Paris, France
| | - Jeanne Duval
- Université Paris Cité, INSERM U1266, Institute of Psychiatry and Neuroscience of Paris, 75014 Paris, France
| | - Rebecca Ann Piskorowski
- Université Paris Cité, INSERM U1266, Institute of Psychiatry and Neuroscience of Paris, 75014 Paris, France; GHU Paris Psychiatrie et Neurosciences, France
| | - Laure Verret
- Research Center on Animal Cognition, Center for Integrative Biology, Toulouse University, CNRS, UPS, 31062 Toulouse, France
| | - Vivien Chevaleyre
- Université Paris Cité, INSERM U1266, Institute of Psychiatry and Neuroscience of Paris, 75014 Paris, France; GHU Paris Psychiatrie et Neurosciences, France.
| |
Collapse
|
9
|
Reeves KC, Shah N, Muñoz B, Atwood BK. Opioid Receptor-Mediated Regulation of Neurotransmission in the Brain. Front Mol Neurosci 2022; 15:919773. [PMID: 35782382 PMCID: PMC9242007 DOI: 10.3389/fnmol.2022.919773] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 05/26/2022] [Indexed: 12/15/2022] Open
Abstract
Opioids mediate their effects via opioid receptors: mu, delta, and kappa. At the neuronal level, opioid receptors are generally inhibitory, presynaptically reducing neurotransmitter release and postsynaptically hyperpolarizing neurons. However, opioid receptor-mediated regulation of neuronal function and synaptic transmission is not uniform in expression pattern and mechanism across the brain. The localization of receptors within specific cell types and neurocircuits determine the effects that endogenous and exogenous opioids have on brain function. In this review we will explore the similarities and differences in opioid receptor-mediated regulation of neurotransmission across different brain regions. We discuss how future studies can consider potential cell-type, regional, and neural pathway-specific effects of opioid receptors in order to better understand how opioid receptors modulate brain function.
Collapse
Affiliation(s)
- Kaitlin C. Reeves
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, United States
- Department of Neuroscience, Charleston Alcohol Research Center, Medical University of South Carolina, Charleston, SC, United States
| | - Nikhil Shah
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, United States
- Medical Scientist Training Program, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Braulio Muñoz
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Brady K. Atwood
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, United States
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, United States
| |
Collapse
|
10
|
Enkephalin release from VIP interneurons in the hippocampal CA2/3a region mediates heterosynaptic plasticity and social memory. Mol Psychiatry 2022; 27:2879-2900. [PMID: 33990774 PMCID: PMC8590711 DOI: 10.1038/s41380-021-01124-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 03/23/2021] [Accepted: 04/13/2021] [Indexed: 12/22/2022]
Abstract
The hippocampus contains a diverse array of inhibitory interneurons that gate information flow through local cortico-hippocampal circuits to regulate memory storage. Although most studies of interneurons have focused on their role in fast synaptic inhibition mediated by GABA release, different classes of interneurons express unique sets of neuropeptides, many of which have been shown to exert powerful effects on neuronal function and memory when applied pharmacologically. However, relatively little is known about whether and how release of endogenous neuropeptides from inhibitory cells contributes to their behavioral role in regulating memory formation. Here we report that vasoactive intestinal peptide (VIP)-expressing interneurons participate in social memory storage by enhancing information transfer from hippocampal CA3 pyramidal neurons to CA2 pyramidal neurons. Notably, this action depends on release of the neuropeptide enkephalin from VIP neurons, causing long-term depression of feedforward inhibition onto CA2 pyramidal cells. Moreover, VIP neuron activity in the CA2 region is increased selectively during exploration of a novel conspecific. Our findings, thus, enhance our appreciation of how GABAergic neurons can regulate synaptic plasticity and mnemonic behavior by demonstrating that such actions can be mediated by release of a specific neuropeptide, rather than through classic fast inhibitory transmission.
Collapse
|
11
|
Rey CC, Robert V, Bouisset G, Loisy M, Lopez S, Cattaud V, Lejards C, Piskorowski RA, Rampon C, Chevaleyre V, Verret L. Altered inhibitory function in hippocampal CA2 contributes in social memory deficits in Alzheimer’s mouse model. iScience 2022; 25:103895. [PMID: 35243253 PMCID: PMC8873612 DOI: 10.1016/j.isci.2022.103895] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 12/07/2021] [Accepted: 02/07/2022] [Indexed: 11/10/2022] Open
Abstract
Parvalbumin (PV)-expressing interneurons which are often associated with the specific extracellular matrix perineuronal net (PNN) play a critical role in the alteration of brain activity and memory performance in Alzheimer’s disease (AD). The integrity of these neurons is crucial for normal functioning of the hippocampal subfield CA2, and hence, social memory formation. Here, we find that social memory deficits of mouse models of AD are associated with decreased presence of PNN around PV cells and long-term synaptic plasticity in area CA2. Furthermore, single local injection of the growth factor neuregulin-1 (NRG1) is sufficient to restore both PV/PNN levels and social memory performance of these mice. Thus, the PV/PNN disruption in area CA2 could play a causal role in social memory deficits of AD mice, and activating PV cell pro-maturation pathways may be sufficient to restore social memory. Tg2576 mouse model of AD have normal sociability, but cannot form social memory Tg2576 mice have less detectable PV interneurons and PNN in hippocampal area CA2 PV-dependent long-term plasticity is altered in CA2 of Tg2576 mice NRG1 in CA2 increases PV/PNN and restores social memory of these AD mice
Collapse
|
12
|
Robert V, Therreau L, Chevaleyre V, Lepicard E, Viollet C, Cognet J, Huang AJ, Boehringer R, Polygalov D, McHugh TJ, Piskorowski RA. Local circuit allowing hypothalamic control of hippocampal area CA2 activity and consequences for CA1. eLife 2021; 10:63352. [PMID: 34003113 PMCID: PMC8154026 DOI: 10.7554/elife.63352] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 05/17/2021] [Indexed: 12/28/2022] Open
Abstract
The hippocampus is critical for memory formation. The hypothalamic supramammillary nucleus (SuM) sends long-range projections to hippocampal area CA2. While the SuM-CA2 connection is critical for social memory, how this input acts on the local circuit is unknown. Using transgenic mice, we found that SuM axon stimulation elicited mixed excitatory and inhibitory responses in area CA2 pyramidal neurons (PNs). Parvalbumin-expressing basket cells were largely responsible for the feedforward inhibitory drive of SuM over area CA2. Inhibition recruited by the SuM input onto CA2 PNs increased the precision of action potential firing both in conditions of low and high cholinergic tone. Furthermore, SuM stimulation in area CA2 modulated CA1 activity, indicating that synchronized CA2 output drives a pulsed inhibition in area CA1. Hence, the network revealed here lays basis for understanding how SuM activity directly acts on the local hippocampal circuit to allow social memory encoding.
Collapse
Affiliation(s)
- Vincent Robert
- INSERM UMR1266, Institute of Psychiatry and Neuroscience of Paris, Team Synaptic Plasticity and Neural Networks, Université de Paris, Paris, France
| | - Ludivine Therreau
- INSERM UMR1266, Institute of Psychiatry and Neuroscience of Paris, Team Synaptic Plasticity and Neural Networks, Université de Paris, Paris, France
| | - Vivien Chevaleyre
- INSERM UMR1266, Institute of Psychiatry and Neuroscience of Paris, Team Synaptic Plasticity and Neural Networks, Université de Paris, Paris, France.,GHU Paris Psychiatrie and Neurosciences, Paris, France
| | - Eude Lepicard
- INSERM UMR1266, Institute of Psychiatry and Neuroscience of Paris, Team Synaptic Plasticity and Neural Networks, Université de Paris, Paris, France
| | - Cécile Viollet
- INSERM UMR1266, Institute of Psychiatry and Neuroscience of Paris, Team Synaptic Plasticity and Neural Networks, Université de Paris, Paris, France
| | - Julie Cognet
- INSERM UMR1266, Institute of Psychiatry and Neuroscience of Paris, Team Synaptic Plasticity and Neural Networks, Université de Paris, Paris, France
| | - Arthur Jy Huang
- Laboratory for Circuit and Behavioral Physiology, RIKEN Center for Brain Science, Saitama, Japan
| | - Roman Boehringer
- Laboratory for Circuit and Behavioral Physiology, RIKEN Center for Brain Science, Saitama, Japan
| | - Denis Polygalov
- Laboratory for Circuit and Behavioral Physiology, RIKEN Center for Brain Science, Saitama, Japan
| | - Thomas J McHugh
- Laboratory for Circuit and Behavioral Physiology, RIKEN Center for Brain Science, Saitama, Japan
| | - Rebecca Ann Piskorowski
- INSERM UMR1266, Institute of Psychiatry and Neuroscience of Paris, Team Synaptic Plasticity and Neural Networks, Université de Paris, Paris, France.,GHU Paris Psychiatrie and Neurosciences, Paris, France
| |
Collapse
|
13
|
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.
Collapse
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.
| |
Collapse
|
14
|
Silkis IG, Markevich VA. Possible Mechanisms of the Influence of the Supramillary Nucleus on the Functioning of the Dentate Gyrus and the CA2 Field of the Hippocamsus (Role of Disinhibition). NEUROCHEM J+ 2020. [DOI: 10.1134/s181971242004011x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
|
15
|
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
| |
Collapse
|
16
|
Dasgupta A, Lim YJ, Kumar K, Baby N, Pang KLK, Benoy A, Behnisch T, Sajikumar S. Group III metabotropic glutamate receptors gate long-term potentiation and synaptic tagging/capture in rat hippocampal area CA2. eLife 2020; 9:e55344. [PMID: 32310084 PMCID: PMC7170650 DOI: 10.7554/elife.55344] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 04/08/2020] [Indexed: 12/17/2022] Open
Abstract
Metabotropic glutamate receptors (mGluRs) play an important role in synaptic plasticity and memory and are largely classified based on amino acid sequence homology and pharmacological properties. Among group III metabotropic glutamate receptors, mGluR7 and mGluR4 show high relative expression in the rat hippocampal area CA2. Group III metabotropic glutamate receptors are known to down-regulate cAMP-dependent signaling pathways via the activation of Gi/o proteins. Here, we provide evidence that inhibition of group III mGluRs by specific antagonists permits an NMDA receptor- and protein synthesis-dependent long-lasting synaptic potentiation in the apparently long-term potentiation (LTP)-resistant Schaffer collateral (SC)-CA2 synapses. Moreover, long-lasting potentiation of these synapses transforms a transient synaptic potentiation of the entorhinal cortical (EC)-CA2 synapses into a stable long-lasting LTP, in accordance with the synaptic tagging/capture hypothesis (STC). Furthermore, this study also sheds light on the role of ERK/MAPK protein signaling and the downregulation of STEP protein in the group III mGluR inhibition-mediated plasticity in the hippocampal CA2 region, identifying them as critical molecular players. Thus, the regulation of group III mGluRs provides a conducive environment for the SC-CA2 synapses to respond to events that could lead to activity-dependent synaptic plasticity.
Collapse
Affiliation(s)
- Ananya Dasgupta
- Department of Physiology, Yong Loo Lin School of Medicine, National University of SingaporeSingaporeSingapore
- Life Sciences Institute Neurobiology Programme, National University of SingaporeSingaporeSingapore
| | - Yu Jia Lim
- Department of Physiology, Yong Loo Lin School of Medicine, National University of SingaporeSingaporeSingapore
| | - Krishna Kumar
- Department of Physiology, Yong Loo Lin School of Medicine, National University of SingaporeSingaporeSingapore
- Life Sciences Institute Neurobiology Programme, National University of SingaporeSingaporeSingapore
| | - Nimmi Baby
- Department of Physiology, Yong Loo Lin School of Medicine, National University of SingaporeSingaporeSingapore
- Life Sciences Institute Neurobiology Programme, National University of SingaporeSingaporeSingapore
| | - Ka Lam Karen Pang
- Department of Physiology, Yong Loo Lin School of Medicine, National University of SingaporeSingaporeSingapore
- Life Sciences Institute Neurobiology Programme, National University of SingaporeSingaporeSingapore
| | - Amrita Benoy
- Department of Physiology, Yong Loo Lin School of Medicine, National University of SingaporeSingaporeSingapore
- Life Sciences Institute Neurobiology Programme, National University of SingaporeSingaporeSingapore
| | - Thomas Behnisch
- Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan UniversityShanghaiChina
| | - Sreedharan Sajikumar
- Department of Physiology, Yong Loo Lin School of Medicine, National University of SingaporeSingaporeSingapore
- Life Sciences Institute Neurobiology Programme, National University of SingaporeSingaporeSingapore
| |
Collapse
|
17
|
Moradi K, Ascoli GA. A comprehensive knowledge base of synaptic electrophysiology in the rodent hippocampal formation. Hippocampus 2020; 30:314-331. [PMID: 31472001 DOI: 10.1101/632760] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 07/16/2019] [Accepted: 08/06/2019] [Indexed: 05/25/2023]
Abstract
The cellular and synaptic architecture of the rodent hippocampus has been described in thousands of peer-reviewed publications. However, no human- or machine-readable public catalog of synaptic electrophysiology data exists for this or any other neural system. Harnessing state-of-the-art information technology, we have developed a cloud-based toolset for identifying empirical evidence from the scientific literature pertaining to synaptic electrophysiology, for extracting the experimental data of interest, and for linking each entry to relevant text or figure excerpts. Mining more than 1,200 published journal articles, we have identified eight different signal modalities quantified by 90 different methods to measure synaptic amplitude, kinetics, and plasticity in hippocampal neurons. We have designed a data structure that both reflects the differences and maintains the existing relations among experimental modalities. Moreover, we mapped every annotated experiment to identified potential connections, that is, specific pairs of presynaptic and postsynaptic neuron types. To this aim, we leveraged Hippocampome.org, an open-access knowledge base of morphologically, electrophysiologically, and molecularly characterized neuron types in the rodent hippocampal formation. Specifically, we have implemented a computational pipeline to systematically translate neuron type properties into formal queries in order to find all compatible potential connections. With this system, we have collected nearly 40,000 synaptic data entities covering 88% of the 3,120 potential connections in Hippocampome.org. Correcting membrane potentials with respect to liquid junction potentials significantly reduced the difference between theoretical and experimental reversal potentials, thereby enabling the accurate conversion of all synaptic amplitudes to conductance. This data set allows for large-scale hypothesis testing of the general rules governing synaptic signals. To illustrate these applications, we confirmed several expected correlations between synaptic measurements and their covariates while suggesting previously unreported ones. We release all data open-source at Hippocampome.org in order to further research across disciplines.
Collapse
Affiliation(s)
- Keivan Moradi
- Neuroscience Program, Krasnow Institute for Advanced Study, George Mason University, Fairfax, Virginia
| | - Giorgio A Ascoli
- Neuroscience Program, Krasnow Institute for Advanced Study, George Mason University, Fairfax, Virginia
- Bioengineering Department, Krasnow Institute for Advanced Study, George Mason University, Fairfax, Virginia
| |
Collapse
|
18
|
Moradi K, Ascoli GA. A comprehensive knowledge base of synaptic electrophysiology in the rodent hippocampal formation. Hippocampus 2020; 30:314-331. [PMID: 31472001 PMCID: PMC7875289 DOI: 10.1002/hipo.23148] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 07/16/2019] [Accepted: 08/06/2019] [Indexed: 01/14/2023]
Abstract
The cellular and synaptic architecture of the rodent hippocampus has been described in thousands of peer-reviewed publications. However, no human- or machine-readable public catalog of synaptic electrophysiology data exists for this or any other neural system. Harnessing state-of-the-art information technology, we have developed a cloud-based toolset for identifying empirical evidence from the scientific literature pertaining to synaptic electrophysiology, for extracting the experimental data of interest, and for linking each entry to relevant text or figure excerpts. Mining more than 1,200 published journal articles, we have identified eight different signal modalities quantified by 90 different methods to measure synaptic amplitude, kinetics, and plasticity in hippocampal neurons. We have designed a data structure that both reflects the differences and maintains the existing relations among experimental modalities. Moreover, we mapped every annotated experiment to identified potential connections, that is, specific pairs of presynaptic and postsynaptic neuron types. To this aim, we leveraged Hippocampome.org, an open-access knowledge base of morphologically, electrophysiologically, and molecularly characterized neuron types in the rodent hippocampal formation. Specifically, we have implemented a computational pipeline to systematically translate neuron type properties into formal queries in order to find all compatible potential connections. With this system, we have collected nearly 40,000 synaptic data entities covering 88% of the 3,120 potential connections in Hippocampome.org. Correcting membrane potentials with respect to liquid junction potentials significantly reduced the difference between theoretical and experimental reversal potentials, thereby enabling the accurate conversion of all synaptic amplitudes to conductance. This data set allows for large-scale hypothesis testing of the general rules governing synaptic signals. To illustrate these applications, we confirmed several expected correlations between synaptic measurements and their covariates while suggesting previously unreported ones. We release all data open-source at Hippocampome.org in order to further research across disciplines.
Collapse
Affiliation(s)
- Keivan Moradi
- Neuroscience Program, Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA (USA)
| | - Giorgio A. Ascoli
- Neuroscience Program, Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA (USA)
- Bioengineering Department, Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA (USA)
| |
Collapse
|
19
|
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.
Collapse
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; ,
| |
Collapse
|
20
|
Domínguez S, Rey CC, Therreau L, Fanton A, Massotte D, Verret L, Piskorowski RA, Chevaleyre V. Maturation of PNN and ErbB4 Signaling in Area CA2 during Adolescence Underlies the Emergence of PV Interneuron Plasticity and Social Memory. Cell Rep 2019; 29:1099-1112.e4. [DOI: 10.1016/j.celrep.2019.09.044] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 07/31/2019] [Accepted: 09/13/2019] [Indexed: 12/28/2022] Open
|
21
|
Reinhard SM, Rais M, Afroz S, Hanania Y, Pendi K, Espinoza K, Rosenthal R, Binder DK, Ethell IM, Razak KA. Reduced perineuronal net expression in Fmr1 KO mice auditory cortex and amygdala is linked to impaired fear-associated memory. Neurobiol Learn Mem 2019; 164:107042. [PMID: 31326533 PMCID: PMC7519848 DOI: 10.1016/j.nlm.2019.107042] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 06/20/2019] [Accepted: 07/10/2019] [Indexed: 02/06/2023]
Abstract
Fragile X Syndrome (FXS) is a leading cause of heritable intellectual disability and autism. Humans with FXS show anxiety, sensory hypersensitivity and impaired learning. The mechanisms of learning impairments can be studied in the mouse model of FXS, the Fmr1 KO mouse, using tone-associated fear memory paradigms. Our previous study reported impaired development of parvalbumin (PV) positive interneurons and perineuronal nets (PNN) in the auditory cortex of Fmr1 KO mice. A recent study suggested PNN dynamics in the auditory cortex following tone-shock association is necessary for fear expression. Together these data suggest that abnormal PNN regulation may underlie tone-fear association learning deficits in Fmr1 KO mice. We tested this hypothesis by quantifying PV and PNN expression in the amygdala, hippocampus and auditory cortex of Fmr1 KO mice following fear conditioning. We found impaired tone-associated memory formation in Fmr1 KO mice. This was paralleled by impaired learning-associated regulation of PNNs in the superficial layers of auditory cortex in Fmr1 KO mice. PV cell density decreased in the auditory cortex in response to fear conditioning in both WT and Fmr1 KO mice. Learning-induced increase of PV expression in the CA3 hippocampus was only observed in WT mice. We also found reduced PNN density in the amygdala and auditory cortex of Fmr1 KO mice in all conditions, as well as reduced PNN intensity in CA2 hippocampus. There was a positive correlation between tone-associated memory and PNN density in the amygdala and auditory cortex, consistent with a tone-association deficit. Altogether our studies suggest a link between impaired PV and PNN regulation within specific regions of the fear conditioning circuit and impaired tone memory formation in Fmr1 KO mice.
Collapse
Affiliation(s)
- Sarah M Reinhard
- Psychology Department and Psychology Graduate Program, University of California, Riverside, CA 92521, USA
| | - Maham Rais
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA 92521, USA
| | - Sonia Afroz
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA 92521, USA
| | - Yasmien Hanania
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA 92521, USA
| | - Kasim Pendi
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA 92521, USA
| | - Katherine Espinoza
- Psychology Department and Psychology Graduate Program, University of California, Riverside, CA 92521, USA; Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA 92521, USA
| | - Robert Rosenthal
- Psychology Department and Psychology Graduate Program, University of California, Riverside, CA 92521, USA
| | - Devin K Binder
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA 92521, USA; Neuroscience Graduate Program, University of California, Riverside, CA 92521, USA
| | - Iryna M Ethell
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA 92521, USA; Neuroscience Graduate Program, University of California, Riverside, CA 92521, USA.
| | - Khaleel A Razak
- Psychology Department and Psychology Graduate Program, University of California, Riverside, CA 92521, USA; Neuroscience Graduate Program, University of California, Riverside, CA 92521, USA.
| |
Collapse
|
22
|
Routing Hippocampal Information Flow through Parvalbumin Interneuron Plasticity in Area CA2. Cell Rep 2019; 27:86-98.e3. [DOI: 10.1016/j.celrep.2019.03.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 12/12/2018] [Accepted: 03/02/2019] [Indexed: 11/23/2022] Open
|
23
|
Helton TD, Zhao M, Farris S, Dudek SM. Diversity of dendritic morphology and entorhinal cortex synaptic effectiveness in mouse CA2 pyramidal neurons. Hippocampus 2018; 29:78-92. [PMID: 30067288 DOI: 10.1002/hipo.23012] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 07/09/2018] [Accepted: 07/11/2018] [Indexed: 11/06/2022]
Abstract
Excitatory synaptic inputs from specific brain regions are often targeted to distinct dendritic arbors on hippocampal pyramidal neurons. Recent work has suggested that CA2 pyramidal neurons respond robustly and preferentially to excitatory input into the stratum lacunosum moleculare (SLM), with a relatively modest response to Schaffer collateral excitatory input into stratum radiatum (SR) in acute mouse hippocampal slices, but the extent to which this difference may be explained by morphology is unknown. In an effort to replicate these findings and to better understand the role of dendritic morphology in shaping responses from proximal and distal synaptic sites, we measured excitatory postsynaptic currents and action potentials in CA2 pyramidal cells in response to SR and SLM stimulation and subsequently analyzed confocal images of the filled cells. We found that, in contrast to previous reports, SR stimulation evoked substantial responses in all recorded CA2 pyramidal cells. Strikingly, however, we found that not all neurons responded to SLM stimulation, and in those neurons that did, responses evoked by SLM and SR were comparable in size and effectiveness in inducing action potentials. In a comprehensive morphometric analysis of CA2 pyramidal cell apical dendrites, we found that the neurons that were unresponsive to SLM stimulation were the same ones that lacked substantial apical dendritic arborization in the SLM. Neurons responsive to both SR and SLM stimulation had roughly equal amounts of dendritic branching in each layer. Remarkably, our study in mouse CA2 generally replicates the work characterizing the diversity of CA2 pyramidal cells in the guinea pig hippocampus. We conclude, then, that like in guinea pig, mouse CA2 pyramidal cells have a diverse apical dendrite morphology that is likely to be reflective of both the amount and source of excitatory input into CA2 from the entorhinal cortex and CA3.
Collapse
Affiliation(s)
- Thomas D Helton
- Neurobiology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina
| | - Meilan Zhao
- Neurobiology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina
| | - Shannon Farris
- Neurobiology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina
| | - Serena M Dudek
- Neurobiology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina
| |
Collapse
|
24
|
Piskorowski RA, Chevaleyre V. Memory circuits: CA2. Curr Opin Neurobiol 2018; 52:54-59. [DOI: 10.1016/j.conb.2018.04.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 04/09/2018] [Indexed: 01/01/2023]
|
25
|
Carstens KE, Dudek SM. Regulation of synaptic plasticity in hippocampal area CA2. Curr Opin Neurobiol 2018; 54:194-199. [PMID: 30120016 DOI: 10.1016/j.conb.2018.07.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 07/26/2018] [Accepted: 07/31/2018] [Indexed: 11/15/2022]
Abstract
Synaptic plasticity in the hippocampus is thought to play a vital role in both the refinement of neuronal circuits during development and in learning in the mature brain. Synapses in hippocampal area CA1 are known for a robust capacity for long-term potentiation (LTP), whereas synapses in the stratum radiatum of hippocampal area CA2 are particularly resistant to such changes. Although we have yet to fully understand the mechanisms behind this resistance to plasticity, a number of genes and extracellular matrix components highly expressed in CA2 appear to function as molecular brakes on plasticity and develop postnatally in the rodent brain. Curiously, the developmental profile of several CA2-enriched molecules is suggestive of a still undefined critical window of plasticity in the hippocampus.
Collapse
Affiliation(s)
- Kelly E Carstens
- Neurobiology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Serena M Dudek
- Neurobiology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA.
| |
Collapse
|
26
|
Benoy A, Dasgupta A, Sajikumar S. Hippocampal area CA2: an emerging modulatory gateway in the hippocampal circuit. Exp Brain Res 2018; 236:919-931. [DOI: 10.1007/s00221-018-5187-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2017] [Accepted: 01/22/2018] [Indexed: 12/18/2022]
|
27
|
Hippocampal area CA2: properties and contribution to hippocampal function. Cell Tissue Res 2018; 373:525-540. [PMID: 29335778 DOI: 10.1007/s00441-017-2769-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 12/07/2017] [Indexed: 12/30/2022]
Abstract
This review focuses on area CA2 of the hippocampus, as recent results have revealed the unique properties and surprising role of this region in encoding social, temporal and contextual aspects of memory. Originally identified and described by Lorente de No, in 1934, this region of the hippocampus has unique intra-and extra-hippocampal connectivity, sending and receiving input to septal and hypothalamic regions. Recent in vivo studies have indicated that CA2 pyramidal neurons encode spatial information during immobility and play an important role in the generation of sharp-wave ripples. Furthermore, CA2 neurons act to control overall excitability in the hippocampal network and have been found to be consistently altered in psychiatric diseases, indicating that normal function of this region is necessary for normal cognition. With its unique role, area CA2 has a unique molecular profile, interneuron density and composition. Furthermore, this region has an unusual manifestation of synaptic plasticity that does not occur post-synaptically at pyramidal neuron dendrities but through the local network of inhibitory neurons. While much progress has recently been made in understanding the large contribution of area CA2 to social memory formation, much still needs to be learned.
Collapse
|
28
|
Billeh YN, Schaub MT. Feedforward architectures driven by inhibitory interactions. J Comput Neurosci 2017; 44:63-74. [PMID: 29139049 DOI: 10.1007/s10827-017-0669-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2017] [Revised: 10/10/2017] [Accepted: 10/17/2017] [Indexed: 11/25/2022]
Abstract
Directed information transmission is paramount for many social, physical, and biological systems. For neural systems, scientists have studied this problem under the paradigm of feedforward networks for decades. In most models of feedforward networks, activity is exclusively driven by excitatory neurons and the wiring patterns between them, while inhibitory neurons play only a stabilizing role for the network dynamics. Motivated by recent experimental discoveries of hippocampal circuitry, cortical circuitry, and the diversity of inhibitory neurons throughout the brain, here we illustrate that one can construct such networks even if the connectivity between the excitatory units in the system remains random. This is achieved by endowing inhibitory nodes with a more active role in the network. Our findings demonstrate that apparent feedforward activity can be caused by a much broader network-architectural basis than often assumed.
Collapse
Affiliation(s)
- Yazan N Billeh
- Computation and Neural Systems Program, California Institute of Technology, Pasadena, CA, USA.
- Allen Institute for Brain Science, Seattle, WA, USA.
| | - Michael T Schaub
- ICTEAM, Université catholique de Louvain, Louvain-la-Neuve, Belgium.
- Institute for Data, Systems, and Society, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Department of Engineering Science, University of Oxford, Oxford, UK.
| |
Collapse
|
29
|
Substance P induces plasticity and synaptic tagging/capture in rat hippocampal area CA2. Proc Natl Acad Sci U S A 2017; 114:E8741-E8749. [PMID: 28973908 DOI: 10.1073/pnas.1711267114] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The hippocampal area Cornu Ammonis (CA) CA2 is important for social interaction and is innervated by Substance P (SP)-expressing supramammillary (SuM) nucleus neurons. SP exerts neuromodulatory effects on pain processing and central synaptic transmission. Here we provide evidence that SP can induce a slowly developing NMDA receptor- and protein synthesis-dependent potentiation of synaptic transmission that can be induced not only at entorhinal cortical (EC)-CA2 synapses but also at long-term potentiation (LTP)-resistant Schaffer collateral (SC)-CA2 synapses. In addition, SP-induced potentiation of SC-CA2 synapses transforms a short-term potentiation of EC-CA2 synaptic transmission into LTP, consistent with the synaptic tagging and capture hypothesis. Interestingly, this SP-induced potentiation and associative interaction between the EC and SC inputs of CA2 neurons is independent of the GABAergic system. In addition, CaMKIV and PKMζ play a critical role in the SP-induced effects on SC-CA2 and EC-CA2 synapses. Thus, afferents from SuM neurons are ideally situated to prime CA2 synapses for the formation of long-lasting plasticity and associativity.
Collapse
|
30
|
Leroy F, Brann DH, Meira T, Siegelbaum SA. Input-Timing-Dependent Plasticity in the Hippocampal CA2 Region and Its Potential Role in Social Memory. Neuron 2017; 95:1089-1102.e5. [PMID: 28823730 DOI: 10.1016/j.neuron.2017.07.036] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 05/26/2017] [Accepted: 07/28/2017] [Indexed: 02/01/2023]
Abstract
Input-timing-dependent plasticity (ITDP) is a circuit-based synaptic learning rule by which paired activation of entorhinal cortical (EC) and Schaffer collateral (SC) inputs to hippocampal CA1 pyramidal neurons (PNs) produces a long-term enhancement of SC excitation. We now find that paired stimulation of EC and SC inputs also induces ITDP of SC excitation of CA2 PNs. However, whereas CA1 ITDP results from long-term depression of feedforward inhibition (iLTD) as a result of activation of CB1 endocannabinoid receptors on cholecystokinin-expressing interneurons, CA2 ITDP results from iLTD through activation of δ-opioid receptors on parvalbumin-expressing interneurons. Furthermore, whereas CA1 ITDP has been previously linked to enhanced specificity of contextual memory, we find that CA2 ITDP is associated with enhanced social memory. Thus, ITDP may provide a general synaptic learning rule for distinct forms of hippocampal-dependent memory mediated by distinct hippocampal regions.
Collapse
Affiliation(s)
- Felix Leroy
- Department of Neuroscience, Kavli Institute of Brain Science, Columbia University Medical Center, 1051 Riverside Drive, New York, NY, USA.
| | - David H Brann
- Department of Neuroscience, Kavli Institute of Brain Science, Columbia University Medical Center, 1051 Riverside Drive, New York, NY, USA
| | - Torcato Meira
- Department of Neuroscience, Kavli Institute of Brain Science, Columbia University Medical Center, 1051 Riverside Drive, New York, NY, USA; Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal; ICVS/3B's, PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Steven A Siegelbaum
- Department of Neuroscience, Kavli Institute of Brain Science, Columbia University Medical Center, 1051 Riverside Drive, New York, NY, USA.
| |
Collapse
|
31
|
Perineuronal Nets Suppress Plasticity of Excitatory Synapses on CA2 Pyramidal Neurons. J Neurosci 2017; 36:6312-20. [PMID: 27277807 DOI: 10.1523/jneurosci.0245-16.2016] [Citation(s) in RCA: 143] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 05/02/2016] [Indexed: 12/19/2022] Open
Abstract
UNLABELLED Long-term potentiation of excitatory synapses on pyramidal neurons in the stratum radiatum rarely occurs in hippocampal area CA2. Here, we present evidence that perineuronal nets (PNNs), a specialized extracellular matrix typically localized around inhibitory neurons, also surround mouse CA2 pyramidal neurons and envelop their excitatory synapses. CA2 pyramidal neurons express mRNA transcripts for the major PNN component aggrecan, identifying these neurons as a novel source for PNNs in the hippocampus. We also found that disruption of PNNs allows synaptic potentiation of normally plasticity-resistant excitatory CA2 synapses; thus, PNNs play a role in restricting synaptic plasticity in area CA2. Finally, we found that postnatal development of PNNs on CA2 pyramidal neurons is modified by early-life enrichment, suggesting that the development of circuits containing CA2 excitatory synapses are sensitive to manipulations of the rearing environment. SIGNIFICANCE STATEMENT Perineuronal nets (PNNs) are thought to play a major role in restricting synaptic plasticity during postnatal development, and are altered in several models of neurodevelopmental disorders, such as schizophrenia and Rett syndrome. Although PNNs have been predominantly studied in association with inhibitory neurons throughout the brain, we describe a dense expression of PNNs around excitatory pyramidal neurons in hippocampal area CA2. We also provide insight into a previously unrecognized role for PNNs in restricting plasticity at excitatory synapses and raise the possibility of an early critical period of hippocampal plasticity that may ultimately reveal a key mechanism underlying learning and memory impairments of PNN-associated neurodevelopmental disorders.
Collapse
|
32
|
Nasrallah K, Piskorowski RA, Chevaleyre V. Bi-directional interplay between proximal and distal inputs to CA2 pyramidal neurons. Neurobiol Learn Mem 2017; 138:173-181. [DOI: 10.1016/j.nlm.2016.06.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 06/22/2016] [Accepted: 06/25/2016] [Indexed: 10/21/2022]
|
33
|
Chevaleyre V, Piskorowski RA. Hippocampal Area CA2: An Overlooked but Promising Therapeutic Target. Trends Mol Med 2016; 22:645-655. [DOI: 10.1016/j.molmed.2016.06.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2016] [Revised: 06/10/2016] [Accepted: 06/10/2016] [Indexed: 10/21/2022]
|
34
|
Abstract
Hippocampal area CA2 has several features that distinguish it from CA1 and CA3, including a unique gene expression profile, failure to display long-term potentiation and relative resistance to cell death. A recent increase in interest in the CA2 region, combined with the development of new methods to define and manipulate its neurons, has led to some exciting new discoveries on the properties of CA2 neurons and their role in behaviour. Here, we review these findings and call attention to the idea that the definition of area CA2 ought to be revised in light of gene expression data.
Collapse
|
35
|
Age-Dependent Specific Changes in Area CA2 of the Hippocampus and Social Memory Deficit in a Mouse Model of the 22q11.2 Deletion Syndrome. Neuron 2016; 89:163-76. [PMID: 26748091 DOI: 10.1016/j.neuron.2015.11.036] [Citation(s) in RCA: 113] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Revised: 09/23/2015] [Accepted: 11/18/2015] [Indexed: 11/23/2022]
Abstract
Several neuropsychiatric disorders are associated with cognitive and social dysfunction. Postmortem studies of patients with schizophrenia have revealed specific changes in area CA2, a long-overlooked region of the hippocampus recently found to be critical for social memory formation. To examine how area CA2 is altered in psychiatric illness, we used the Df(16)A(+/-) mouse model of the 22q11.2 microdeletion, a genetic risk factor for developing several neuropsychiatric disorders, including schizophrenia. We report several age-dependent CA2 alterations: a decrease in the density of parvalbumin-expressing interneurons, a reduction in the amount of feedforward inhibition, and a change in CA2 pyramidal-neuron intrinsic properties. Furthermore, we found that area CA2 is less plastic in Df(16)A(+/-) mice, making it nearly impossible to evoke action potential firing in CA2 pyramidal neurons. Finally, we show that Df(16)A(+/-) mice display impaired social cognition, providing a potential mechanism and a neural substrate for this impairment in psychiatric disorders.
Collapse
|
36
|
Antic SD, Empson RM, Knöpfel T. Voltage imaging to understand connections and functions of neuronal circuits. J Neurophysiol 2016; 116:135-52. [PMID: 27075539 DOI: 10.1152/jn.00226.2016] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 04/11/2016] [Indexed: 12/30/2022] Open
Abstract
Understanding of the cellular mechanisms underlying brain functions such as cognition and emotions requires monitoring of membrane voltage at the cellular, circuit, and system levels. Seminal voltage-sensitive dye and calcium-sensitive dye imaging studies have demonstrated parallel detection of electrical activity across populations of interconnected neurons in a variety of preparations. A game-changing advance made in recent years has been the conceptualization and development of optogenetic tools, including genetically encoded indicators of voltage (GEVIs) or calcium (GECIs) and genetically encoded light-gated ion channels (actuators, e.g., channelrhodopsin2). Compared with low-molecular-weight calcium and voltage indicators (dyes), the optogenetic imaging approaches are 1) cell type specific, 2) less invasive, 3) able to relate activity and anatomy, and 4) facilitate long-term recordings of individual cells' activities over weeks, thereby allowing direct monitoring of the emergence of learned behaviors and underlying circuit mechanisms. We highlight the potential of novel approaches based on GEVIs and compare those to calcium imaging approaches. We also discuss how novel approaches based on GEVIs (and GECIs) coupled with genetically encoded actuators will promote progress in our knowledge of brain circuits and systems.
Collapse
Affiliation(s)
- Srdjan D Antic
- Stem Cell Institute, Institute for Systems Genomics, UConn Health, Farmington, Connecticut
| | - Ruth M Empson
- Department of Physiology, Brain Research New Zealand, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand; and
| | - Thomas Knöpfel
- Division of Brain Sciences, Department of Medicine and Centre for Neurotechnology, Institute of Biomedical Engineering, Imperial College London, London, United Kingdom
| |
Collapse
|