1
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Huang YC, Chen HC, Lin YT, Lin ST, Zheng Q, Abdelfattah AS, Lavis LD, Schreiter ER, Lin BJ, Chen TW. Dynamic assemblies of parvalbumin interneurons in brain oscillations. Neuron 2024; 112:2600-2613.e5. [PMID: 38955183 DOI: 10.1016/j.neuron.2024.05.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 03/21/2024] [Accepted: 05/10/2024] [Indexed: 07/04/2024]
Abstract
Brain oscillations are crucial for perception, memory, and behavior. Parvalbumin-expressing (PV) interneurons are critical for these oscillations, but their population dynamics remain unclear. Using voltage imaging, we simultaneously recorded membrane potentials in up to 26 PV interneurons in vivo during hippocampal ripple oscillations in mice. We found that PV cells generate ripple-frequency rhythms by forming highly dynamic cell assemblies. These assemblies exhibit rapid and significant changes from cycle to cycle, varying greatly in both size and membership. Importantly, this variability is not just random spiking failures of individual neurons. Rather, the activities of other PV cells contain significant information about whether a PV cell spikes or not in a given cycle. This coordination persists without network oscillations, and it exists in subthreshold potentials even when the cells are not spiking. Dynamic assemblies of interneurons may provide a new mechanism to modulate postsynaptic dynamics and impact cognitive functions flexibly and rapidly.
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Affiliation(s)
- Yi-Chieh Huang
- Institute of Neuroscience, National Yang Ming Chiao Tung University, Taipei 112, Taiwan
| | - Hui-Ching Chen
- Institute of Neuroscience, National Yang Ming Chiao Tung University, Taipei 112, Taiwan
| | - Yu-Ting Lin
- Institute of Neuroscience, National Yang Ming Chiao Tung University, Taipei 112, Taiwan
| | - Szu-Ting Lin
- Institute of Neuroscience, National Yang Ming Chiao Tung University, Taipei 112, Taiwan
| | - Qinsi Zheng
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Ahmed S Abdelfattah
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA; Department of Neuroscience, Brown University, Providence, RI, USA; Carney Institute for Brain Science, Brown University, Providence, RI, USA
| | - Luke D Lavis
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Eric R Schreiter
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Bei-Jung Lin
- Institute of Neuroscience, National Yang Ming Chiao Tung University, Taipei 112, Taiwan; Brain Research Center, National Yang Ming Chiao Tung University, Taipei 112, Taiwan.
| | - Tsai-Wen Chen
- Institute of Neuroscience, National Yang Ming Chiao Tung University, Taipei 112, Taiwan; Brain Research Center, National Yang Ming Chiao Tung University, Taipei 112, Taiwan.
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2
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Chamberland S, Grant G, Machold R, Nebet ER, Tian G, Stich J, Hanani M, Kullander K, Tsien RW. Functional specialization of hippocampal somatostatin-expressing interneurons. Proc Natl Acad Sci U S A 2024; 121:e2306382121. [PMID: 38640347 PMCID: PMC11047068 DOI: 10.1073/pnas.2306382121] [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: 04/23/2023] [Accepted: 02/27/2024] [Indexed: 04/21/2024] Open
Abstract
Hippocampal somatostatin-expressing (Sst) GABAergic interneurons (INs) exhibit considerable anatomical and functional heterogeneity. Recent single-cell transcriptome analyses have provided a comprehensive Sst-IN subpopulations census, a plausible molecular ground truth of neuronal identity whose links to specific functionality remain incomplete. Here, we designed an approach to identify and access subpopulations of Sst-INs based on transcriptomic features. Four mouse models based on single or combinatorial Cre- and Flp- expression differentiated functionally distinct subpopulations of CA1 hippocampal Sst-INs that largely tiled the morpho-functional parameter space of the Sst-INs superfamily. Notably, the Sst;;Tac1 intersection revealed a population of bistratified INs that preferentially synapsed onto fast-spiking interneurons (FS-INs) and were sufficient to interrupt their firing. In contrast, the Ndnf;;Nkx2-1 intersection identified a population of oriens lacunosum-moleculare INs that predominantly targeted CA1 pyramidal neurons, avoiding FS-INs. Overall, our results provide a framework to translate neuronal transcriptomic identity into discrete functional subtypes that capture the diverse specializations of hippocampal Sst-INs.
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Affiliation(s)
- Simon Chamberland
- New York University Neuroscience Institute, New York University Grossman School of Medicine, New York University, New York, NY10016
- Department of Neuroscience and Physiology, New York University, New York, NY10016
| | - Gariel Grant
- New York University Neuroscience Institute, New York University Grossman School of Medicine, New York University, New York, NY10016
- Department of Neuroscience and Physiology, New York University, New York, NY10016
| | - Robert Machold
- New York University Neuroscience Institute, New York University Grossman School of Medicine, New York University, New York, NY10016
- Department of Neuroscience and Physiology, New York University, New York, NY10016
| | - Erica R. Nebet
- New York University Neuroscience Institute, New York University Grossman School of Medicine, New York University, New York, NY10016
- Department of Neuroscience and Physiology, New York University, New York, NY10016
| | - Guoling Tian
- New York University Neuroscience Institute, New York University Grossman School of Medicine, New York University, New York, NY10016
- Department of Neuroscience and Physiology, New York University, New York, NY10016
| | - Joshua Stich
- New York University Neuroscience Institute, New York University Grossman School of Medicine, New York University, New York, NY10016
- Department of Neuroscience and Physiology, New York University, New York, NY10016
| | - Monica Hanani
- New York University Neuroscience Institute, New York University Grossman School of Medicine, New York University, New York, NY10016
- Department of Neuroscience and Physiology, New York University, New York, NY10016
| | - Klas Kullander
- Developmental Genetics, Department of Neuroscience, Uppsala University, Uppsala, Uppsala län752 37, Sweden
| | - Richard W. Tsien
- New York University Neuroscience Institute, New York University Grossman School of Medicine, New York University, New York, NY10016
- Center for Neural Science, New York University, New York, NY10003
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3
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Tamboli S, Singh S, Topolnik D, El Amine Barkat M, Radhakrishnan R, Guet-McCreight A, Topolnik L. Mouse hippocampal CA1 VIP interneurons detect novelty in the environment and support recognition memory. Cell Rep 2024; 43:114115. [PMID: 38607918 DOI: 10.1016/j.celrep.2024.114115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 02/17/2024] [Accepted: 03/29/2024] [Indexed: 04/14/2024] Open
Abstract
In the CA1 hippocampus, vasoactive intestinal polypeptide-expressing interneurons (VIP-INs) play a prominent role in disinhibitory circuit motifs. However, the specific behavioral conditions that lead to circuit disinhibition remain uncertain. To investigate the behavioral relevance of VIP-IN activity, we employed wireless technologies allowing us to monitor and manipulate their function in freely behaving mice. Our findings reveal that, during spatial exploration in new environments, VIP-INs in the CA1 hippocampal region become highly active, facilitating the rapid encoding of novel spatial information. Remarkably, both VIP-INs and pyramidal neurons (PNs) exhibit increased activity when encountering novel changes in the environment, including context- and object-related alterations. Concurrently, somatostatin- and parvalbumin-expressing inhibitory populations show an inverse relationship with VIP-IN and PN activity, revealing circuit disinhibition that occurs on a timescale of seconds. Thus, VIP-IN-mediated disinhibition may constitute a crucial element in the rapid encoding of novelty and the acquisition of recognition memory.
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Affiliation(s)
- Suhel Tamboli
- Neuroscience Axis, CRCHUQ-CHUL, Quebec City, PQ, Canada; Department of Biochemistry, Microbiology, and Bioinformatics, Université Laval, Quebec City, PQ, Canada
| | - Sanjay Singh
- Neuroscience Axis, CRCHUQ-CHUL, Quebec City, PQ, Canada; Department of Biochemistry, Microbiology, and Bioinformatics, Université Laval, Quebec City, PQ, Canada
| | - Dimitry Topolnik
- Neuroscience Axis, CRCHUQ-CHUL, Quebec City, PQ, Canada; Department of Biochemistry, Microbiology, and Bioinformatics, Université Laval, Quebec City, PQ, Canada
| | - Mohamed El Amine Barkat
- Neuroscience Axis, CRCHUQ-CHUL, Quebec City, PQ, Canada; Department of Biochemistry, Microbiology, and Bioinformatics, Université Laval, Quebec City, PQ, Canada
| | - Risna Radhakrishnan
- Neuroscience Axis, CRCHUQ-CHUL, Quebec City, PQ, Canada; Department of Biochemistry, Microbiology, and Bioinformatics, Université Laval, Quebec City, PQ, Canada
| | | | - Lisa Topolnik
- Neuroscience Axis, CRCHUQ-CHUL, Quebec City, PQ, Canada; Department of Biochemistry, Microbiology, and Bioinformatics, Université Laval, Quebec City, PQ, Canada.
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4
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Kopsick JD, Kilgore JA, Adam GC, Ascoli GA. Formation and Retrieval of Cell Assemblies in a Biologically Realistic Spiking Neural Network Model of Area CA3 in the Mouse Hippocampus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.27.586909. [PMID: 38585941 PMCID: PMC10996657 DOI: 10.1101/2024.03.27.586909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
The hippocampal formation is critical for episodic memory, with area Cornu Ammonis 3 (CA3) a necessary substrate for auto-associative pattern completion. Recent theoretical and experimental evidence suggests that the formation and retrieval of cell assemblies enable these functions. Yet, how cell assemblies are formed and retrieved in a full-scale spiking neural network (SNN) of CA3 that incorporates the observed diversity of neurons and connections within this circuit is not well understood. Here, we demonstrate that a data-driven SNN model quantitatively reflecting the neuron type-specific population sizes, intrinsic electrophysiology, connectivity statistics, synaptic signaling, and long-term plasticity of the mouse CA3 is capable of robust auto-association and pattern completion via cell assemblies. Our results show that a broad range of assembly sizes could successfully and systematically retrieve patterns from heavily incomplete or corrupted cues after a limited number of presentations. Furthermore, performance was robust with respect to partial overlap of assemblies through shared cells, substantially enhancing memory capacity. These novel findings provide computational evidence that the specific biological properties of the CA3 circuit produce an effective neural substrate for associative learning in the mammalian brain.
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Affiliation(s)
- Jeffrey D. Kopsick
- Center for Neural Informatics, Structures, & Plasticity, College of Engineering and Computing, George Mason University, Fairfax, VA, United States
- Interdisciplinary Program in Neuroscience, College of Science, George Mason University, Fairfax, VA, United States
| | - Joseph A. Kilgore
- Department of Electrical and Computer Engineering, George Washington University, Washington, D.C., United States
| | - Gina C. Adam
- Department of Electrical and Computer Engineering, George Washington University, Washington, D.C., United States
| | - Giorgio A. Ascoli
- Center for Neural Informatics, Structures, & Plasticity, College of Engineering and Computing, George Mason University, Fairfax, VA, United States
- Interdisciplinary Program in Neuroscience, College of Science, George Mason University, Fairfax, VA, United States
- Bioengineering Department, College of Engineering and Computing, George Mason University, Fairfax, VA, United States
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5
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Pochinok I, Stöber TM, Triesch J, Chini M, Hanganu-Opatz IL. A developmental increase of inhibition promotes the emergence of hippocampal ripples. Nat Commun 2024; 15:738. [PMID: 38272901 PMCID: PMC10810866 DOI: 10.1038/s41467-024-44983-z] [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: 08/14/2023] [Accepted: 01/10/2024] [Indexed: 01/27/2024] Open
Abstract
Sharp wave-ripples (SPW-Rs) are a hippocampal network phenomenon critical for memory consolidation and planning. SPW-Rs have been extensively studied in the adult brain, yet their developmental trajectory is poorly understood. While SPWs have been recorded in rodents shortly after birth, the time point and mechanisms of ripple emergence are still unclear. Here, we combine in vivo electrophysiology with optogenetics and chemogenetics in 4 to 12-day-old mice to address this knowledge gap. We show that ripples are robustly detected and induced by light stimulation of channelrhodopsin-2-transfected CA1 pyramidal neurons only from postnatal day 10 onwards. Leveraging a spiking neural network model, we mechanistically link the maturation of inhibition and ripple emergence. We corroborate these findings by reducing ripple rate upon chemogenetic silencing of CA1 interneurons. Finally, we show that early SPW-Rs elicit a more robust prefrontal cortex response than SPWs lacking ripples. Thus, development of inhibition promotes ripples emergence.
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Affiliation(s)
- Irina Pochinok
- Institute of Developmental Neurophysiology, Center for Molecular Neurobiology (ZMNH), Hamburg Center of Neuroscience (HCNS), University Medical Center Hamburg-Eppendorf, 20251, Hamburg, Germany
| | - Tristan M Stöber
- Frankfurt Institute for Advanced Studies, 60438, Frankfurt am Main, Germany
| | - Jochen Triesch
- Frankfurt Institute for Advanced Studies, 60438, Frankfurt am Main, Germany
| | - Mattia Chini
- Institute of Developmental Neurophysiology, Center for Molecular Neurobiology (ZMNH), Hamburg Center of Neuroscience (HCNS), University Medical Center Hamburg-Eppendorf, 20251, Hamburg, Germany.
| | - Ileana L Hanganu-Opatz
- Institute of Developmental Neurophysiology, Center for Molecular Neurobiology (ZMNH), Hamburg Center of Neuroscience (HCNS), University Medical Center Hamburg-Eppendorf, 20251, Hamburg, Germany.
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6
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Hainmueller T, Cazala A, Huang LW, Bartos M. Subfield-specific interneuron circuits govern the hippocampal response to novelty in male mice. Nat Commun 2024; 15:714. [PMID: 38267409 PMCID: PMC10808551 DOI: 10.1038/s41467-024-44882-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Accepted: 01/04/2024] [Indexed: 01/26/2024] Open
Abstract
The hippocampus is the brain's center for episodic memories. Its subregions, the dentate gyrus and CA1-3, are differentially involved in memory encoding and recall. Hippocampal principal cells represent episodic features like movement, space, and context, but less is known about GABAergic interneurons. Here, we performed two-photon calcium imaging of parvalbumin- and somatostatin-expressing interneurons in the dentate gyrus and CA1-3 of male mice exploring virtual environments. Parvalbumin-interneurons increased activity with running-speed and reduced it in novel environments. Somatostatin-interneurons in CA1-3 behaved similar to parvalbumin-expressing cells, but their dentate gyrus counterparts increased activity during rest and in novel environments. Congruently, chemogenetic silencing of dentate parvalbumin-interneurons had prominent effects in familiar contexts, while silencing somatostatin-expressing cells increased similarity of granule cell representations between novel and familiar environments. Our data indicate unique roles for parvalbumin- and somatostatin-positive interneurons in the dentate gyrus that are distinct from those in CA1-3 and may support routing of novel information.
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Affiliation(s)
- Thomas Hainmueller
- Institute for Physiology I, University of Freiburg, Medical Faculty, 79104, Freiburg, Germany.
- NYU Neuroscience Institute, 435 East 30th Street, New York, NY, 10016, USA.
- Department of Psychiatry, New York University Langone Medical Center, New York, NY, 10016, USA.
| | - Aurore Cazala
- Institute for Physiology I, University of Freiburg, Medical Faculty, 79104, Freiburg, Germany
| | - Li-Wen Huang
- Institute for Physiology I, University of Freiburg, Medical Faculty, 79104, Freiburg, Germany
| | - Marlene Bartos
- Institute for Physiology I, University of Freiburg, Medical Faculty, 79104, Freiburg, Germany.
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7
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Ruelas M, Medina-Ceja L, Fuentes-Aguilar RQ. A scoping review of the relationship between alcohol, memory consolidation and ripple activity: An overview of common methodologies to analyse ripples. Eur J Neurosci 2023; 58:4137-4154. [PMID: 37827165 DOI: 10.1111/ejn.16168] [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: 03/28/2022] [Revised: 08/27/2023] [Accepted: 09/26/2023] [Indexed: 10/14/2023]
Abstract
Alcohol abuse is not only responsible for 5.3% of the total deaths in the world but also has a substantial impact on neurological and memory disabilities throughout the population. One extensively studied brain area involved in cognitive functions is the hippocampus. Evidence in several rodent models has shown that ethanol produces cognitive impairment in hippocampal-dependent tasks and that the damage is varied according to the stage of development at which the rodent was exposed to ethanol and the dose. To the authors' knowledge, there is a biomarker for cognitive processes in the hippocampus that remains relatively understudied in association with memory impairment by alcohol administration. This biomarker is called sharp wave-ripples (SWRs) which are synchronous neuronal population events that are well known to be involved in memory consolidation. Methodologies for facilitated or automatic identification of ripples and their analysis have been reported for a wider bandwidth than SWRs. This review is focused on communicating the state of the art about the relationship between alcohol, memory consolidation and ripple activity, as well as the use of the common methodologies to identify SWRs automatically.
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Affiliation(s)
- Marina Ruelas
- School of Engineering and Sciences, Tecnológico de Monterrey, Zapopan, Jalisco, Mexico
| | - Laura Medina-Ceja
- Laboratory of Neurophysiology, Department of Cellular and Molecular Biology, CUCBA, University of Guadalajara, Zapopan, Jalisco, Mexico
| | - Rita Q Fuentes-Aguilar
- Institute of Advanced Materials for Sustainable Manufacturing, Tecnológico de Monterrey, Zapopan, Jalisco, Mexico
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8
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Tzilivaki A, Tukker JJ, Maier N, Poirazi P, Sammons RP, Schmitz D. Hippocampal GABAergic interneurons and memory. Neuron 2023; 111:3154-3175. [PMID: 37467748 PMCID: PMC10593603 DOI: 10.1016/j.neuron.2023.06.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 01/04/2023] [Accepted: 06/21/2023] [Indexed: 07/21/2023]
Abstract
One of the most captivating questions in neuroscience revolves around the brain's ability to efficiently and durably capture and store information. It must process continuous input from sensory organs while also encoding memories that can persist throughout a lifetime. What are the cellular-, subcellular-, and network-level mechanisms that underlie this remarkable capacity for long-term information storage? Furthermore, what contributions do distinct types of GABAergic interneurons make to this process? As the hippocampus plays a pivotal role in memory, our review focuses on three aspects: (1) delineation of hippocampal interneuron types and their connectivity, (2) interneuron plasticity, and (3) activity patterns of interneurons during memory-related rhythms, including the role of long-range interneurons and disinhibition. We explore how these three elements, together showcasing the remarkable diversity of inhibitory circuits, shape the processing of memories in the hippocampus.
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Affiliation(s)
- Alexandra Tzilivaki
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität Berlin, and Berlin Institute of Health, Neuroscience Research Center, 10117 Berlin, Germany; Einstein Center for Neurosciences, Chariteplatz 1, 10117 Berlin, Germany; NeuroCure Cluster of Excellence, Chariteplatz 1, 10117 Berlin, Germany
| | - John J Tukker
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität Berlin, and Berlin Institute of Health, Neuroscience Research Center, 10117 Berlin, Germany; German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
| | - Nikolaus Maier
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität Berlin, and Berlin Institute of Health, Neuroscience Research Center, 10117 Berlin, Germany
| | - Panayiota Poirazi
- Foundation for Research and Technology Hellas (FORTH), Institute of Molecular Biology and Biotechnology (IMBB), N. Plastira 100, Heraklion, Crete, Greece
| | - Rosanna P Sammons
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität Berlin, and Berlin Institute of Health, Neuroscience Research Center, 10117 Berlin, Germany
| | - Dietmar Schmitz
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität Berlin, and Berlin Institute of Health, Neuroscience Research Center, 10117 Berlin, Germany; Einstein Center for Neurosciences, Chariteplatz 1, 10117 Berlin, Germany; NeuroCure Cluster of Excellence, Chariteplatz 1, 10117 Berlin, Germany; German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany; Bernstein Center for Computational Neuroscience, Humboldt-Universität zu Berlin, Philippstrasse. 13, 10115 Berlin, Germany; Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Robert-Rössle-Straße 10, 13125 Berlin, Germany.
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9
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Michon FX, Laplante I, Bosson A, Robitaille R, Lacaille JC. mTORC1-mediated acquisition of reward-related representations by hippocampal somatostatin interneurons. Mol Brain 2023; 16:55. [PMID: 37400913 DOI: 10.1186/s13041-023-01042-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 06/03/2023] [Indexed: 07/05/2023] Open
Abstract
Plasticity of principal cells and inhibitory interneurons underlies hippocampal memory. Bidirectional modulation of somatostatin cell mTORC1 activity, a crucial translational control mechanism in synaptic plasticity, causes parallel changes in hippocampal CA1 somatostatin interneuron (SOM-IN) long-term potentiation and hippocampus-dependent memory, indicating a key role in learning. However, SOM-IN activity changes and behavioral correlates during learning, and the role of mTORC1 in these processes, remain ill-defined. To address these questions, we used two-photon Ca2+ imaging from SOM-INs during a virtual reality goal-directed spatial memory task in head-fixed control mice (SOM-IRES-Cre mice) or in mice with conditional knockout of Rptor (SOM-Rptor-KO mice) to block mTORC1 activity in SOM-INs. We found that control mice learn the task, but SOM-Raptor-KO mice exhibit a deficit. Also, SOM-IN Ca2+ activity became increasingly related to reward during learning in control mice but not in SOM-Rptor-KO mice. Four types of SOM-IN activity patterns related to reward location were observed, "reward off sustained", "reward off transient", "reward on sustained" and "reward on transient", and these responses showed reorganization after reward relocation in control but not SOM-Rptor-KO mice. Thus, SOM-INs develop mTORC1-dependent reward- related activity during learning. This coding may bi-directionally interact with pyramidal cells and other structures to represent and consolidate reward location.
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Affiliation(s)
- François-Xavier Michon
- Department of Neurosciences, Center for Interdisciplinary Research on Brain and Learning (CIRCA) and Research Group on Neural Signaling and Circuitry (GRSNC), Université de Montréal, Montreal, QC, H3C 3J7, Canada
| | - Isabel Laplante
- Department of Neurosciences, Center for Interdisciplinary Research on Brain and Learning (CIRCA) and Research Group on Neural Signaling and Circuitry (GRSNC), Université de Montréal, Montreal, QC, H3C 3J7, Canada
| | - Anthony Bosson
- Department of Neurosciences, Center for Interdisciplinary Research on Brain and Learning (CIRCA) and Research Group on Neural Signaling and Circuitry (GRSNC), Université de Montréal, Montreal, QC, H3C 3J7, Canada
| | - Richard Robitaille
- Department of Neurosciences, Center for Interdisciplinary Research on Brain and Learning (CIRCA) and Research Group on Neural Signaling and Circuitry (GRSNC), Université de Montréal, Montreal, QC, H3C 3J7, Canada
| | - Jean-Claude Lacaille
- Department of Neurosciences, Center for Interdisciplinary Research on Brain and Learning (CIRCA) and Research Group on Neural Signaling and Circuitry (GRSNC), Université de Montréal, Montreal, QC, H3C 3J7, Canada.
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10
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Kopsick JD, Tecuatl C, Moradi K, Attili SM, Kashyap HJ, Xing J, Chen K, Krichmar JL, Ascoli GA. Robust Resting-State Dynamics in a Large-Scale Spiking Neural Network Model of Area CA3 in the Mouse Hippocampus. Cognit Comput 2023; 15:1190-1210. [PMID: 37663748 PMCID: PMC10473858 DOI: 10.1007/s12559-021-09954-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Accepted: 10/10/2021] [Indexed: 12/19/2022]
Abstract
Hippocampal area CA3 performs the critical auto-associative function underlying pattern completion in episodic memory. Without external inputs, the electrical activity of this neural circuit reflects the spontaneous spiking interplay among glutamatergic pyramidal neurons and GABAergic interneurons. However, the network mechanisms underlying these resting-state firing patterns are poorly understood. Leveraging the Hippocampome.org knowledge base, we developed a data-driven, large-scale spiking neural network (SNN) model of mouse CA3 with 8 neuron types, 90,000 neurons, 51 neuron-type specific connections, and 250,000,000 synapses. We instantiated the SNN in the CARLsim4 multi-GPU simulation environment using the Izhikevich and Tsodyks-Markram formalisms for neuronal and synaptic dynamics, respectively. We analyzed the resultant population activity upon transient activation. The SNN settled into stable oscillations with a biologically plausible grand-average firing frequency, which was robust relative to a wide range of transient activation. The diverse firing patterns of individual neuron types were consistent with existing knowledge of cell type-specific activity in vivo. Altered network structures that lacked neuron- or connection-type specificity were neither stable nor robust, highlighting the importance of neuron type circuitry. Additionally, external inputs reflecting dentate mossy fibers shifted the observed rhythms to the gamma band. We freely released the CARLsim4-Hippocampome framework on GitHub to test hippocampal hypotheses. Our SNN may be useful to investigate the circuit mechanisms underlying the computational functions of CA3. Moreover, our approach can be scaled to the whole hippocampal formation, which may contribute to elucidating how the unique neuronal architecture of this system subserves its crucial cognitive roles.
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Affiliation(s)
- Jeffrey D. Kopsick
- Interdepartmental Program in Neuroscience, George Mason University, Fairfax, VA, USA
| | - Carolina Tecuatl
- Bioengineering Department, Volgenau School of Engineering, George Mason University, Fairfax, VA, USA
| | - Keivan Moradi
- Interdepartmental Program in Neuroscience, George Mason University, Fairfax, VA, USA
| | - Sarojini M. Attili
- Interdepartmental Program in Neuroscience, George Mason University, Fairfax, VA, USA
| | - Hirak J. Kashyap
- Department of Computer Science, University of California, Irvine, Irvine, CA, USA
| | - Jinwei Xing
- Department of Cognitive Sciences, University of California, Irvine, Irvine, CA, USA
| | - Kexin Chen
- Department of Cognitive Sciences, University of California, Irvine, Irvine, CA, USA
| | - Jeffrey L. Krichmar
- Department of Cognitive Sciences, University of California, Irvine, Irvine, CA, USA
- Department of Computer Science, University of California, Irvine, Irvine, CA, USA
| | - Giorgio A. Ascoli
- Interdepartmental Program in Neuroscience, George Mason University, Fairfax, VA, USA
- Bioengineering Department, Volgenau School of Engineering, George Mason University, Fairfax, VA, USA
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11
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Forro T, Klausberger T. Differential behavior-related activity of distinct hippocampal interneuron types during odor-associated spatial navigation. Neuron 2023:S0896-6273(23)00380-X. [PMID: 37279749 DOI: 10.1016/j.neuron.2023.05.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Revised: 04/02/2023] [Accepted: 05/10/2023] [Indexed: 06/08/2023]
Abstract
Hippocampal pyramidal cells represent an animal's position in space together with specific contexts and events. However, it is largely unknown how distinct types of GABAergic interneurons contribute to such computations. We recorded from the intermediate CA1 hippocampus of head-fixed mice exhibiting odor-to-place memory associations during navigation in a virtual reality (VR). The presence of an odor cue and its prediction of a different reward location induced a remapping of place cell activity in the virtual maze. Based on this, we performed extracellular recording and juxtacellular labeling of identified interneurons during task performance. The activity of parvalbumin (PV)-expressing basket, but not of PV-expressing bistratified cells, reflected the expected contextual change in the working-memory-related sections of the maze. Some interneurons, including identified cholecystokinin-expressing cells, decreased activity during visuospatial navigation and increased activity during reward. Our findings suggest that distinct types of GABAergic interneuron are differentially involved in cognitive processes of the hippocampus.
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Affiliation(s)
- Thomas Forro
- Division of Cognitive Neurobiology, Center for Brain Research, Medical University of Vienna, 1090 Vienna, Austria.
| | - Thomas Klausberger
- Division of Cognitive Neurobiology, Center for Brain Research, Medical University of Vienna, 1090 Vienna, Austria.
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12
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Chamberland S, Grant G, Machold R, Nebet ER, Tian G, Hanani M, Kullander K, Tsien RW. Functional specialization of hippocampal somatostatin-expressing interneurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.27.538511. [PMID: 37162922 PMCID: PMC10168348 DOI: 10.1101/2023.04.27.538511] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Hippocampal somatostatin-expressing (Sst) GABAergic interneurons (INs) exhibit considerable anatomical and functional heterogeneity. Recent single cell transcriptome analyses have provided a comprehensive Sst-IN subtype census, a plausible molecular ground truth of neuronal identity whose links to specific functionality remain incomplete. Here, we designed an approach to identify and access subpopulations of Sst-INs based on transcriptomic features. Four mouse models based on single or combinatorial Cre- and Flp- expression differentiated functionally distinct subpopulations of CA1 hippocampal Sst-INs that largely tiled the morpho-functional parameter space of the Sst-INs superfamily. Notably, the Sst;;Tac1 intersection revealed a population of bistratified INs that preferentially synapsed onto fast-spiking interneurons (FS-INs) and were both necessary and sufficient to interrupt their firing. In contrast, the Ndnf;;Nkx2-1 intersection identified a population of oriens lacunosum-moleculare (OLM) INs that predominantly targeted CA1 pyramidal neurons, avoiding FS-INs. Overall, our results provide a framework to translate neuronal transcriptomic identity into discrete functional subtypes that capture the diverse specializations of hippocampal Sst-INs.
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Affiliation(s)
- Simon Chamberland
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY 10016, USA
| | - Gariel Grant
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY 10016, USA
| | - Robert Machold
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY 10016, USA
| | - Erica R. Nebet
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY 10016, USA
| | - Guoling Tian
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY 10016, USA
| | - Monica Hanani
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY 10016, USA
| | - Klas Kullander
- Developmental Genetics, Department of Neuroscience, Uppsala University, Uppsala 752 37, Uppsala län, Sweden
| | - Richard W. Tsien
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY 10016, USA
- Center for Neural Science, New York University, New York, NY, 10003, USA
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13
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Chamberland S, Nebet ER, Valero M, Hanani M, Egger R, Larsen SB, Eyring KW, Buzsáki G, Tsien RW. Brief synaptic inhibition persistently interrupts firing of fast-spiking interneurons. Neuron 2023; 111:1264-1281.e5. [PMID: 36787751 PMCID: PMC10121938 DOI: 10.1016/j.neuron.2023.01.017] [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: 12/28/2020] [Revised: 06/06/2022] [Accepted: 01/18/2023] [Indexed: 02/16/2023]
Abstract
Neurons perform input-output operations that integrate synaptic inputs with intrinsic electrical properties; these operations are generally constrained by the brevity of synaptic events. Here, we report that sustained firing of CA1 hippocampal fast-spiking parvalbumin-expressing interneurons (PV-INs) can be persistently interrupted for several hundred milliseconds following brief GABAAR-mediated inhibition in vitro and in vivo. A single presynaptic neuron could interrupt PV-IN firing, occasionally with a single action potential (AP), and reliably with AP bursts. Experiments and computational modeling reveal that the persistent interruption of firing maintains neurons in a depolarized, quiescent state through a cell-autonomous mechanism. Interrupted PV-INs are strikingly responsive to Schaffer collateral inputs. The persistent interruption of firing provides a disinhibitory circuit mechanism favoring spike generation in CA1 pyramidal cells. Overall, our results demonstrate that neuronal silencing can far outlast brief synaptic inhibition owing to the well-tuned interplay between neurotransmitter release and postsynaptic membrane dynamics, a phenomenon impacting microcircuit function.
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Affiliation(s)
- Simon Chamberland
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY 10016, USA.
| | - Erica R Nebet
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY 10016, USA
| | - Manuel Valero
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY 10016, USA
| | - Monica Hanani
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY 10016, USA
| | - Robert Egger
- NYU Neuroscience Institute and Department of Otolaryngology, NYU Langone Medical Center, New York, NY 10016, USA; Center for Neural Science, New York University, New York, NY 10003, USA
| | - Samantha B Larsen
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY 10016, USA
| | - Katherine W Eyring
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY 10016, USA
| | - György Buzsáki
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY 10016, USA; Center for Neural Science, New York University, New York, NY 10003, USA; Department of Neurology, Langone Medical Center, New York University, New York, NY, USA
| | - Richard W Tsien
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY 10016, USA; Center for Neural Science, New York University, New York, NY 10003, USA.
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14
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Lévesque M, Wang S, Macey-Dare ADB, Salami P, Avoli M. Evolution of interictal activity in models of mesial temporal lobe epilepsy. Neurobiol Dis 2023; 180:106065. [PMID: 36907521 DOI: 10.1016/j.nbd.2023.106065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 02/22/2023] [Accepted: 03/02/2023] [Indexed: 03/12/2023] Open
Abstract
Interictal activity and seizures are the hallmarks of focal epileptic disorders (which include mesial temporal lobe epilepsy, MTLE) in humans and in animal models. Interictal activity, which is recorded with cortical and intracerebral EEG recordings, comprises spikes, sharp waves and high-frequency oscillations, and has been used in clinical practice to identify the epileptic zone. However, its relation with seizures remains debated. Moreover, it is unclear whether specific EEG changes in interictal activity occur during the time preceding the appearance of spontaneous seizures. This period, which is termed "latent", has been studied in rodent models of MTLE in which spontaneous seizures start to occur following an initial insult (most often a status epilepticus induced by convulsive drugs such as kainic acid or pilocarpine) and may mirror epileptogenesis, i.e., the process leading the brain to develop an enduring predisposition to seizure generation. Here, we will address this topic by reviewing experimental studies performed in MTLE models. Specifically, we will review data highlighting the dynamic changes in interictal spiking activity and high-frequency oscillations occurring during the latent period, and how optogenetic stimulation of specific cell populations can modulate them in the pilocarpine model. These findings indicate that interictal activity: (i) is heterogeneous in its EEG patterns and thus, presumably, in its underlying neuronal mechanisms; and (ii) can pinpoint to the epileptogenic processes occurring in focal epileptic disorders in animal models and, perhaps, in epileptic patients.
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Affiliation(s)
- Maxime Lévesque
- Montreal Neurological Institute-Hospital and Departments of Neurology & Neurosurgery, McGill University, 3801 Rue University, Montreal, H3A 2B4, QC, Canada.
| | - Siyan Wang
- Montreal Neurological Institute-Hospital and Departments of Neurology & Neurosurgery, McGill University, 3801 Rue University, Montreal, H3A 2B4, QC, Canada
| | - Anežka D B Macey-Dare
- Montreal Neurological Institute-Hospital and Departments of Neurology & Neurosurgery, McGill University, 3801 Rue University, Montreal, H3A 2B4, QC, Canada; Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Pariya Salami
- Montreal Neurological Institute-Hospital and Departments of Neurology & Neurosurgery, McGill University, 3801 Rue University, Montreal, H3A 2B4, QC, Canada; Department of Neurology, Massachusetts General Hospital and Harvard Medical School, 55 Fruit St., Boston, MA 02114, USA
| | - Massimo Avoli
- Montreal Neurological Institute-Hospital and Departments of Neurology & Neurosurgery, McGill University, 3801 Rue University, Montreal, H3A 2B4, QC, Canada; Department of Physiology, McGill University, 3655 Promenade Sir William Osler, Montreal, H3G 1Y6, QC, Canada
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15
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Goldenberg AM, Schmidt S, Mitelman R, Levy DR, Prigge M, Katz Y, Yizhar O, Beck H, Lampl I. Localized chemogenetic silencing of inhibitory neurons: a novel mouse model of focal cortical epileptic activity. Cereb Cortex 2023; 33:2838-2856. [PMID: 35788286 DOI: 10.1093/cercor/bhac245] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 05/17/2022] [Accepted: 05/18/2022] [Indexed: 11/13/2022] Open
Abstract
Focal cortical epilepsies are frequently refractory to available anticonvulsant drug therapies. One key factor contributing to this state is the limited availability of animal models that allow to reliably study focal cortical seizures and how they recruit surrounding brain areas in vivo. In this study, we selectively expressed the inhibitory chemogenetic receptor, hM4D, in GABAergic neurons in focal cortical areas using viral gene transfer. GABAergic silencing using Clozapine-N-Oxide (CNO) demonstrated reliable induction of local epileptiform events in the electroencephalogram signal of awake freely moving mice. Anesthetized mice experiments showed consistent induction of focal epileptiform-events in both the barrel cortex (BC) and the medial prefrontal cortex (mPFC), accompanied by high-frequency oscillations, a known characteristic of human seizures. Epileptiform-events showed propagation indication with favored propagation pathways: from the BC on 1 hemisphere to its counterpart and from the BC to the mPFC, but not vice-versa. Lastly, sensory whisker-pad stimulation evoked BC epileptiform events post-CNO, highlighting the potential use of this model in studying sensory-evoked seizures. Combined, our results show that targeted chemogenetic inhibition of GABAergic neurons using hM4D can serve as a novel, versatile, and reliable model of focal cortical epileptic activity suitable for systematically studying cortical ictogenesis in different cortical areas.
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Affiliation(s)
- Adi Miriam Goldenberg
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Sarah Schmidt
- Institute for Experimental Epileptology and Cognition Research, Life and Brain Center, University of Bonn, Bonn 53105, Germany
| | - Rea Mitelman
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Dana Rubi Levy
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Matthias Prigge
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Yonatan Katz
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Ofer Yizhar
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Heinz Beck
- Institute for Experimental Epileptology and Cognition Research, Life and Brain Center, University of Bonn, Bonn 53105, Germany
| | - Ilan Lampl
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
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16
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Single-Cell Labeling Strategies to Dissect Neuronal Structures and Local Functions. BIOLOGY 2023; 12:biology12020321. [PMID: 36829594 PMCID: PMC9953318 DOI: 10.3390/biology12020321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 02/09/2023] [Accepted: 02/14/2023] [Indexed: 02/19/2023]
Abstract
The brain network consists of ten billion neurons and is the most complex structure in the universe. Understanding the structure of complex brain networks and neuronal functions is one of the main goals of modern neuroscience. Since the seminal invention of Golgi staining, single-cell labeling methods have been among the most potent approaches for dissecting neuronal structures and neural circuits. Furthermore, the development of sparse single-cell transgenic methods has enabled single-cell gene knockout studies to examine the local functions of various genes in neural circuits and synapses. Here, we review non-transgenic single-cell labeling methods and recent advances in transgenic strategies for sparse single neuronal labeling. These methods and strategies will fundamentally contribute to the understanding of brain structure and function.
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17
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Lai N, Li Z, Xu C, Wang Y, Chen Z. Diverse nature of interictal oscillations: EEG-based biomarkers in epilepsy. Neurobiol Dis 2023; 177:105999. [PMID: 36638892 DOI: 10.1016/j.nbd.2023.105999] [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: 12/02/2022] [Revised: 01/07/2023] [Accepted: 01/09/2023] [Indexed: 01/11/2023] Open
Abstract
Interictal electroencephalogram (EEG) patterns, including high-frequency oscillations (HFOs), interictal spikes (ISs), and slow wave activities (SWAs), are defined as specific oscillations between seizure events. These interictal oscillations reflect specific dynamic changes in network excitability and play various roles in epilepsy. In this review, we briefly describe the electrographic characteristics of HFOs, ISs, and SWAs in the interictal state, and discuss the underlying cellular and network mechanisms. We also summarize representative evidence from experimental and clinical epilepsy to address their critical roles in ictogenesis and epileptogenesis, indicating their potential as electrophysiological biomarkers of epilepsy. Importantly, we put forwards some perspectives for further research in the field.
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Affiliation(s)
- Nanxi Lai
- Institute of Pharmacology & Toxicology, NHC and CAMS Key Laboratory of Medical Neurobiology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Zhisheng Li
- Institute of Pharmacology & Toxicology, NHC and CAMS Key Laboratory of Medical Neurobiology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Cenglin Xu
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou, China
| | - Yi Wang
- Institute of Pharmacology & Toxicology, NHC and CAMS Key Laboratory of Medical Neurobiology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China; Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou, China
| | - Zhong Chen
- Institute of Pharmacology & Toxicology, NHC and CAMS Key Laboratory of Medical Neurobiology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China; Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou, China; Epilepsy Center, Department of Neurology, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
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18
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Mysin I, Shubina L. Hippocampal non-theta state: The "Janus face" of information processing. Front Neural Circuits 2023; 17:1134705. [PMID: 36960401 PMCID: PMC10027749 DOI: 10.3389/fncir.2023.1134705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Accepted: 02/14/2023] [Indexed: 03/09/2023] Open
Abstract
The vast majority of studies on hippocampal rhythms have been conducted on animals or humans in situations where their attention was focused on external stimuli or solving cognitive tasks. These studies formed the basis for the idea that rhythmical activity coordinates the work of neurons during information processing. However, at rest, when attention is not directed to external stimuli, brain rhythms do not disappear, although the parameters of oscillatory activity change. What is the functional load of rhythmical activity at rest? Hippocampal oscillatory activity during rest is called the non-theta state, as opposed to the theta state, a characteristic activity during active behavior. We dedicate our review to discussing the present state of the art in the research of the non-theta state. The key provisions of the review are as follows: (1) the non-theta state has its own characteristics of oscillatory and neuronal activity; (2) hippocampal non-theta state is possibly caused and maintained by change of rhythmicity of medial septal input under the influence of raphe nuclei; (3) there is no consensus in the literature about cognitive functions of the non-theta-non-ripple state; and (4) the antagonistic relationship between theta and delta rhythms observed in rodents is not always observed in humans. Most attention is paid to the non-theta-non-ripple state, since this aspect of hippocampal activity has not been investigated properly and discussed in reviews.
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19
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The role of inhibitory circuits in hippocampal memory processing. Nat Rev Neurosci 2022; 23:476-492. [DOI: 10.1038/s41583-022-00599-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/22/2022] [Indexed: 11/08/2022]
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20
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Szabo GG, Farrell JS, Dudok B, Hou WH, Ortiz AL, Varga C, Moolchand P, Gulsever CI, Gschwind T, Dimidschstein J, Capogna M, Soltesz I. Ripple-selective GABAergic projection cells in the hippocampus. Neuron 2022; 110:1959-1977.e9. [PMID: 35489331 DOI: 10.1016/j.neuron.2022.04.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 02/10/2022] [Accepted: 04/04/2022] [Indexed: 10/18/2022]
Abstract
Ripples are brief high-frequency electrographic events with important roles in episodic memory. However, the in vivo circuit mechanisms coordinating ripple-related activity among local and distant neuronal ensembles are not well understood. Here, we define key characteristics of a long-distance projecting GABAergic cell group in the mouse hippocampus that selectively exhibits high-frequency firing during ripples while staying largely silent during theta-associated states when most other GABAergic cells are active. The high ripple-associated firing commenced before ripple onset and reached its maximum before ripple peak, with the signature theta-OFF, ripple-ON firing pattern being preserved across awake and sleep states. Controlled by septal GABAergic, cholinergic, and CA3 glutamatergic inputs, these ripple-selective cells innervate parvalbumin and cholecystokinin-expressing local interneurons while also targeting a variety of extra-hippocampal regions. These results demonstrate the existence of a hippocampal GABAergic circuit element that is uniquely positioned to coordinate ripple-related neuronal dynamics across neuronal assemblies.
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Affiliation(s)
- Gergely G Szabo
- Department of Neurosurgery, Stanford University, Stanford, CA, USA.
| | - Jordan S Farrell
- Department of Neurosurgery, Stanford University, Stanford, CA, USA
| | - Barna Dudok
- Department of Neurosurgery, Stanford University, Stanford, CA, USA
| | - Wen-Hsien Hou
- Department of Biomedicine, Aarhus University, Aarhus, Denmark; DANDRITE, The Danish Research Institute of Translational Neuroscience, Aarhus University, Aarhus, Denmark
| | - Anna L Ortiz
- Department of Neurosurgery, Stanford University, Stanford, CA, USA
| | - Csaba Varga
- Department of Neurosurgery, Stanford University, Stanford, CA, USA
| | | | | | - Tilo Gschwind
- Department of Neurosurgery, Stanford University, Stanford, CA, USA
| | - Jordane Dimidschstein
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Marco Capogna
- Department of Biomedicine, Aarhus University, Aarhus, Denmark; DANDRITE, The Danish Research Institute of Translational Neuroscience, Aarhus University, Aarhus, Denmark; Center for Proteins in Memory - PROMEMO, Danish National Research Foundation, Aarhus University, Aarhus, Denmark
| | - Ivan Soltesz
- Department of Neurosurgery, Stanford University, Stanford, CA, USA
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21
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Rolotti SV, Blockus H, Sparks FT, Priestley JB, Losonczy A. Reorganization of CA1 dendritic dynamics by hippocampal sharp-wave ripples during learning. Neuron 2022; 110:977-991.e4. [PMID: 35041805 PMCID: PMC8930454 DOI: 10.1016/j.neuron.2021.12.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 07/23/2021] [Accepted: 12/10/2021] [Indexed: 12/17/2022]
Abstract
The hippocampus plays a critical role in memory consolidation, mediated by coordinated network activity during sharp-wave ripple (SWR) events. Despite the link between SWRs and hippocampal plasticity, little is known about how network state affects information processing in dendrites, the primary sites of synaptic input integration and plasticity. Here, we monitored somatic and basal dendritic activity in CA1 pyramidal cells in behaving mice using longitudinal two-photon calcium imaging integrated with simultaneous local field potential recordings. We found immobility was associated with an increase in dendritic activity concentrated during SWRs. Coincident dendritic and somatic activity during SWRs predicted increased coupling during subsequent exploration of a novel environment. In contrast, somatic-dendritic coupling and SWR recruitment varied with cells' tuning distance to reward location during a goal-learning task. Our results connect SWRs with the stabilization of information processing within CA1 neurons and suggest that these mechanisms may be dynamically biased by behavioral demands.
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Affiliation(s)
- Sebi V Rolotti
- Department of Neuroscience, Columbia University, New York, NY 10027, USA; Doctoral Program in Neurobiology and Behavior, Columbia University, New York, NY 10027, USA; Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA.
| | - Heike Blockus
- Department of Neuroscience, Columbia University, New York, NY 10027, USA; Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Fraser T Sparks
- Department of Neuroscience, Columbia University, New York, NY 10027, USA; Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
| | - James B Priestley
- Department of Neuroscience, Columbia University, New York, NY 10027, USA; Doctoral Program in Neurobiology and Behavior, Columbia University, New York, NY 10027, USA; Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Attila Losonczy
- Department of Neuroscience, Columbia University, New York, NY 10027, USA; Mortimer B. 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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22
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Braun W, Memmesheimer RM. High-frequency oscillations and sequence generation in two-population models of hippocampal region CA1. PLoS Comput Biol 2022; 18:e1009891. [PMID: 35176028 PMCID: PMC8890743 DOI: 10.1371/journal.pcbi.1009891] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 03/02/2022] [Accepted: 02/02/2022] [Indexed: 11/19/2022] Open
Abstract
Hippocampal sharp wave/ripple oscillations are a prominent pattern of collective activity, which consists of a strong overall increase of activity with superimposed (140 − 200 Hz) ripple oscillations. Despite its prominence and its experimentally demonstrated importance for memory consolidation, the mechanisms underlying its generation are to date not understood. Several models assume that recurrent networks of inhibitory cells alone can explain the generation and main characteristics of the ripple oscillations. Recent experiments, however, indicate that in addition to inhibitory basket cells, the pattern requires in vivo the activity of the local population of excitatory pyramidal cells. Here, we study a model for networks in the hippocampal region CA1 incorporating such a local excitatory population of pyramidal neurons. We start by investigating its ability to generate ripple oscillations using extensive simulations. Using biologically plausible parameters, we find that short pulses of external excitation triggering excitatory cell spiking are required for sharp/wave ripple generation with oscillation patterns similar to in vivo observations. Our model has plausible values for single neuron, synapse and connectivity parameters, random connectivity and no strong feedforward drive to the inhibitory population. Specifically, whereas temporally broad excitation can lead to high-frequency oscillations in the ripple range, sparse pyramidal cell activity is only obtained with pulse-like external CA3 excitation. Further simulations indicate that such short pulses could originate from dendritic spikes in the apical or basal dendrites of CA1 pyramidal cells, which are triggered by coincident spike arrivals from hippocampal region CA3. Finally we show that replay of sequences by pyramidal neurons and ripple oscillations can arise intrinsically in CA1 due to structured connectivity that gives rise to alternating excitatory pulse and inhibitory gap coding; the latter denotes phases of silence in specific basket cell groups, which induce selective disinhibition of groups of pyramidal neurons. This general mechanism for sequence generation leads to sparse pyramidal cell and dense basket cell spiking, does not rely on synfire chain-like feedforward excitation and may be relevant for other brain regions as well.
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Affiliation(s)
- Wilhelm Braun
- Neural Network Dynamics and Computation, Institute of Genetics, University of Bonn, Bonn, Germany
- Institute of Computational Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- * E-mail: (WB); (R-MM)
| | - Raoul-Martin Memmesheimer
- Neural Network Dynamics and Computation, Institute of Genetics, University of Bonn, Bonn, Germany
- * E-mail: (WB); (R-MM)
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23
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Marks WD, Yamamoto N, Kitamura T. Complementary roles of differential medial entorhinal cortex inputs to the hippocampus for the formation and integration of temporal and contextual memory (Systems Neuroscience). Eur J Neurosci 2021; 54:6762-6779. [PMID: 32277786 PMCID: PMC8187108 DOI: 10.1111/ejn.14737] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 03/28/2020] [Accepted: 03/30/2020] [Indexed: 11/29/2022]
Abstract
In humans and rodents, the entorhinal cortical (EC)-hippocampal (HPC) circuit is crucial for the formation and recall of memory, preserving both spatial information and temporal information about the occurrence of past events. Both modeling and experimental studies have revealed circuits within this network that play crucial roles in encoding space and context. However, our understanding about the time-related aspects of memory is just beginning to be understood. In this review, we first describe updates regarding recent anatomical discoveries for the EC-HPC network, as several important neural circuits critical for memory formation have been discovered by newly developed neural tracing technologies. Second, we examine the complementary roles of multiple medial entorhinal cortical inputs, including newly discovered circuits, into the hippocampus for the temporal and spatial aspects of memory. Finally, we will discuss how temporal and contextual memory information is integrated in HPC cornu ammonis 1 cells. We provide new insights into the neural circuit mechanisms for anatomical and functional segregation and integration of the temporal and spatial aspects of memory encoding in the EC-HPC networks.
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Affiliation(s)
- William D. Marks
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, 75390, USA
| | - Naoki Yamamoto
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, 75390, USA
| | - Takashi Kitamura
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, 75390, USA
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, Texas, 75390, USA
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Gordon PC, Dörre S, Belardinelli P, Stenroos M, Zrenner B, Ziemann U, Zrenner C. Prefrontal Theta-Phase Synchronized Brain Stimulation With Real-Time EEG-Triggered TMS. Front Hum Neurosci 2021; 15:691821. [PMID: 34234662 PMCID: PMC8255809 DOI: 10.3389/fnhum.2021.691821] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 05/27/2021] [Indexed: 11/30/2022] Open
Abstract
Background Theta-band neuronal oscillations in the prefrontal cortex are associated with several cognitive functions. Oscillatory phase is an important correlate of excitability and phase synchrony mediates information transfer between neuronal populations oscillating at that frequency. The ability to extract and exploit the prefrontal theta rhythm in real time in humans would facilitate insight into neurophysiological mechanisms of cognitive processes involving the prefrontal cortex, and development of brain-state-dependent stimulation for therapeutic applications. Objectives We investigate individual source-space beamforming-based estimation of the prefrontal theta oscillation as a method to target specific phases of the ongoing theta oscillations in the human dorsomedial prefrontal cortex (DMPFC) with real-time EEG-triggered transcranial magnetic stimulation (TMS). Different spatial filters for extracting the prefrontal theta oscillation from EEG signals are compared and additional signal quality criteria are assessed to take into account the dynamics of this cortical oscillation. Methods Twenty two healthy participants were recruited for anatomical MRI scans and EEG recordings with 18 composing the final analysis. We calculated individual spatial filters based on EEG beamforming in source space. The extracted EEG signal was then used to simulate real-time phase-detection and quantify the accuracy as compared to post-hoc phase estimates. Different spatial filters and triggering parameters were compared. Finally, we validated the feasibility of this approach by actual real-time triggering of TMS pulses at different phases of the prefrontal theta oscillation. Results Higher phase-detection accuracy was achieved using individualized source-based spatial filters, as compared to an average or standard Laplacian filter, and also by detecting and avoiding periods of low theta amplitude and periods containing a phase reset. Using optimized parameters, prefrontal theta-phase synchronized TMS of DMPFC was achieved with an accuracy of ±55°. Conclusion This study demonstrates the feasibility of triggering TMS pulses during different phases of the ongoing prefrontal theta oscillation in real time. This method is relevant for brain state-dependent stimulation in human studies of cognition. It will also enable new personalized therapeutic repetitive TMS protocols for more effective treatment of neuropsychiatric disorders.
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Affiliation(s)
- Pedro Caldana Gordon
- Department of Neurology and Stroke, University of Tübingen, Tübingen, Germany.,Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Sara Dörre
- Department of Neurology and Stroke, University of Tübingen, Tübingen, Germany.,Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Paolo Belardinelli
- Department of Neurology and Stroke, University of Tübingen, Tübingen, Germany.,Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany.,CIMeC, Center for Mind/Brain Sciences, University of Trento, Rovereto, Italy
| | - Matti Stenroos
- Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland
| | - Brigitte Zrenner
- Department of Neurology and Stroke, University of Tübingen, Tübingen, Germany.,Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Ulf Ziemann
- Department of Neurology and Stroke, University of Tübingen, Tübingen, Germany.,Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Christoph Zrenner
- Department of Neurology and Stroke, University of Tübingen, Tübingen, Germany.,Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
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25
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Hájos N. Interneuron Types and Their Circuits in the Basolateral Amygdala. Front Neural Circuits 2021; 15:687257. [PMID: 34177472 PMCID: PMC8222668 DOI: 10.3389/fncir.2021.687257] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 05/11/2021] [Indexed: 11/29/2022] Open
Abstract
The basolateral amygdala (BLA) is a cortical structure based on its cell types, connectivity features, and developmental characteristics. This part of the amygdala is considered to be the main entry site of processed and multisensory information delivered via cortical and thalamic afferents. Although GABAergic inhibitory cells in the BLA comprise only 20% of the entire neuronal population, they provide essential control over proper network operation. Previous studies have uncovered that GABAergic cells in the basolateral amygdala are as diverse as those present in other cortical regions, including the hippocampus and neocortex. To understand the role of inhibitory cells in various amygdala functions, we need to reveal the connectivity and input-output features of the different types of GABAergic cells. Here, I review the recent achievements in uncovering the diversity of GABAergic cells in the basolateral amygdala with a specific focus on the microcircuit organization of these inhibitory cells.
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Affiliation(s)
- Norbert Hájos
- Laboratory of Network Neurophysiology, ELRN Institute of Experimental Medicine, Budapest, Hungary
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26
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Honoré E, Khlaifia A, Bosson A, Lacaille JC. Hippocampal Somatostatin Interneurons, Long-Term Synaptic Plasticity and Memory. Front Neural Circuits 2021; 15:687558. [PMID: 34149368 PMCID: PMC8206813 DOI: 10.3389/fncir.2021.687558] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 04/30/2021] [Indexed: 12/13/2022] Open
Abstract
A distinctive feature of the hippocampal structure is the diversity of inhibitory interneurons. These complex inhibitory interconnections largely contribute to the tight modulation of hippocampal circuitry, as well as to the formation and coordination of neuronal assemblies underlying learning and memory. Inhibitory interneurons provide more than a simple transitory inhibition of hippocampal principal cells (PCs). The synaptic plasticity of inhibitory neurons provides long-lasting changes in the hippocampal network and is a key component of memory formation. The dendrite targeting interneurons expressing the peptide somatostatin (SOM) are particularly interesting in this regard because they display unique long-lasting synaptic changes leading to metaplastic regulation of hippocampal networks. In this article, we examine the actions of the neuropeptide SOM on hippocampal cells, synaptic plasticity, learning, and memory. We address the different subtypes of hippocampal SOM interneurons. We describe the long-term synaptic plasticity that takes place at the excitatory synapses of SOM interneurons, its singular induction and expression mechanisms, as well as the consequences of these changes on the hippocampal network, learning, and memory. We also review evidence that astrocytes provide cell-specific dynamic regulation of inhibition of PC dendrites by SOM interneurons. Finally, we cover how, in mouse models of Alzheimer’s disease (AD), dysfunction of plasticity of SOM interneuron excitatory synapses may also contribute to cognitive impairments in brain disorders.
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Affiliation(s)
- Eve Honoré
- Department of Neurosciences, Centre for Interdisciplinary Research on Brain and Learning, Research Group on the Central Nervous System, Université de Montréal, Montreal, QC, Canada
| | - Abdessattar Khlaifia
- Department of Neurosciences, Centre for Interdisciplinary Research on Brain and Learning, Research Group on the Central Nervous System, Université de Montréal, Montreal, QC, Canada
| | - Anthony Bosson
- Department of Neurosciences, Centre for Interdisciplinary Research on Brain and Learning, Research Group on the Central Nervous System, Université de Montréal, Montreal, QC, Canada
| | - Jean-Claude Lacaille
- Department of Neurosciences, Centre for Interdisciplinary Research on Brain and Learning, Research Group on the Central Nervous System, Université de Montréal, Montreal, QC, Canada
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Andreakos N, Yue S, Cutsuridis V. Quantitative investigation of memory recall performance of a computational microcircuit model of the hippocampus. Brain Inform 2021; 8:9. [PMID: 33963952 PMCID: PMC8106564 DOI: 10.1186/s40708-021-00131-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Accepted: 04/13/2021] [Indexed: 12/05/2022] Open
Abstract
Memory, the process of encoding, storing, and maintaining information over time to influence future actions, is very important in our lives. Losing it, it comes with a great cost. Deciphering the biophysical mechanisms leading to recall improvement should thus be of outmost importance. In this study, we embarked on the quest to improve computationally the recall performance of a bio-inspired microcircuit model of the mammalian hippocampus, a brain region responsible for the storage and recall of short-term declarative memories. The model consisted of excitatory and inhibitory cells. The cell properties followed closely what is currently known from the experimental neurosciences. Cells’ firing was timed to a theta oscillation paced by two distinct neuronal populations exhibiting highly regular bursting activity, one tightly coupled to the trough and the other to the peak of theta. An excitatory input provided to excitatory cells context and timing information for retrieval of previously stored memory patterns. Inhibition to excitatory cells acted as a non-specific global threshold machine that removed spurious activity during recall. To systematically evaluate the model’s recall performance against stored patterns, pattern overlap, network size, and active cells per pattern, we selectively modulated feedforward and feedback excitatory and inhibitory pathways targeting specific excitatory and inhibitory cells. Of the different model variations (modulated pathways) tested, ‘model 1’ recall quality was excellent across all conditions. ‘Model 2’ recall was the worst. The number of ‘active cells’ representing a memory pattern was the determining factor in improving the model’s recall performance regardless of the number of stored patterns and overlap between them. As ‘active cells per pattern’ decreased, the model’s memory capacity increased, interference effects between stored patterns decreased, and recall quality improved.
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Affiliation(s)
- Nikolaos Andreakos
- School of Computer Science, University of Lincoln, Brayford Pool, Lincoln, LN6 7TS, UK
| | - Shigang Yue
- School of Computer Science, University of Lincoln, Brayford Pool, Lincoln, LN6 7TS, UK
| | - Vassilis Cutsuridis
- School of Computer Science, University of Lincoln, Brayford Pool, Lincoln, LN6 7TS, UK. .,Lincoln Sleep Research Center, University of Lincoln, Lincoln, LN6 7TS, UK.
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28
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Sanchez-Aguilera A, Wheeler DW, Jurado-Parras T, Valero M, Nokia MS, Cid E, Fernandez-Lamo I, Sutton N, García-Rincón D, de la Prida LM, Ascoli GA. An update to Hippocampome.org by integrating single-cell phenotypes with circuit function in vivo. PLoS Biol 2021; 19:e3001213. [PMID: 33956790 PMCID: PMC8130934 DOI: 10.1371/journal.pbio.3001213] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 05/18/2021] [Accepted: 03/30/2021] [Indexed: 02/03/2023] Open
Abstract
Understanding brain operation demands linking basic behavioral traits to cell-type specific dynamics of different brain-wide subcircuits. This requires a system to classify the basic operational modes of neurons and circuits. Single-cell phenotyping of firing behavior during ongoing oscillations in vivo has provided a large body of evidence on entorhinal-hippocampal function, but data are dispersed and diverse. Here, we mined literature to search for information regarding the phase-timing dynamics of over 100 hippocampal/entorhinal neuron types defined in Hippocampome.org. We identified missing and unresolved pieces of knowledge (e.g., the preferred theta phase for a specific neuron type) and complemented the dataset with our own new data. By confronting the effect of brain state and recording methods, we highlight the equivalences and differences across conditions and offer a number of novel observations. We show how a heuristic approach based on oscillatory features of morphologically identified neurons can aid in classifying extracellular recordings of single cells and discuss future opportunities and challenges towards integrating single-cell phenotypes with circuit function.
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Affiliation(s)
| | - Diek W. Wheeler
- Bioengineering Department, Volgenau School of Engineering, George Mason University, Virginia, United States of America
| | | | - Manuel Valero
- Instituto Cajal CSIC, Madrid, Spain
- NYU Neuroscience Institute, New York, United States of America
| | - Miriam S. Nokia
- Instituto Cajal CSIC, Madrid, Spain
- Department of Psychology, University of Jyvaskyla, Jyvaskyla, Finland
- Neuroscience Center, HiLIFE, University of Helsinki, Helsinki, Finland
| | | | | | - Nate Sutton
- Bioengineering Department, Volgenau School of Engineering, George Mason University, Virginia, United States of America
| | | | | | - Giorgio A. Ascoli
- Bioengineering Department, Volgenau School of Engineering, George Mason University, Virginia, United States of America
- * E-mail: (LMP); (GAA)
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29
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Total Number and Ratio of GABAergic Neuron Types in the Mouse Lateral and Basal Amygdala. J Neurosci 2021; 41:4575-4595. [PMID: 33837051 DOI: 10.1523/jneurosci.2700-20.2021] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 03/14/2021] [Accepted: 03/28/2021] [Indexed: 12/18/2022] Open
Abstract
GABAergic neurons are key circuit elements in cortical networks. Despite growing evidence showing that inhibitory cells play a critical role in the lateral (LA) and basal (BA) amygdala functions, neither the number of GABAergic neurons nor the ratio of their distinct types has been determined in these amygdalar nuclei. Using unbiased stereology, we found that the ratio of GABAergic neurons in the BA (22%) is significantly higher than in the LA (16%) in both male and female mice. No difference was observed between the right and left hemispheres in either sex. In addition, we assessed the ratio of the major inhibitory cell types in both amygdalar nuclei. Using transgenic mice and a viral strategy for visualizing inhibitory cells combined with immunocytochemistry, we estimated that the following cell types together compose the vast majority of GABAergic cells in the LA and BA: axo-axonic cells (5.5%-6%), basket cells expressing parvalbumin (17%-20%) or cholecystokinin (7%-9%), dendrite-targeting inhibitory cells expressing somatostatin (10%-16%), NPY-containing neurogliaform cells (14%-15%), VIP and/or calretinin-expressing interneuron-selective interneurons (29%-38%), and GABAergic projection neurons expressing somatostatin and neuronal nitric oxide synthase (5.5%-8%). Our results show that these amygdalar nuclei contain all major GABAergic neuron types as found in other cortical regions. Furthermore, our data offer an essential reference for future studies aiming to reveal changes in GABAergic cell number and in inhibitory cell types typically observed under different pathologic conditions, and to model functioning amygdalar networks in health and disease.SIGNIFICANCE STATEMENT GABAergic cells in cortical structures, as in the lateral and basal nucleus of the amygdala, have a determinant role in controlling circuit operation. In this study, we provide the first estimate for the total number of inhibitory cells in these two amygdalar nuclei. In addition, our study is the first to define the ratio of the major GABAergic cell types present in these cortical networks. Taking into account that hyperexcitability in the amygdala, arising from the imbalance between excitation and inhibition typifies many altered brain functions, including anxiety, post-traumatic stress disorder, schizophrenia, and autism, uncovering the number and ratio of distinct amygdalar inhibitory cell types offers a solid base for comparing the changes in inhibition in pathologic brain states.
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30
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Comprehensive Estimates of Potential Synaptic Connections in Local Circuits of the Rodent Hippocampal Formation by Axonal-Dendritic Overlap. J Neurosci 2020; 41:1665-1683. [PMID: 33361464 DOI: 10.1523/jneurosci.1193-20.2020] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 10/19/2020] [Accepted: 12/13/2020] [Indexed: 12/12/2022] Open
Abstract
A quantitative description of the hippocampal formation synaptic architecture is essential for understanding the neural mechanisms of episodic memory. Yet the existing knowledge of connectivity statistics between different neuron types in the rodent hippocampus only captures a mere 5% of this circuitry. We present a systematic pipeline to produce first-approximation estimates for most of the missing information. Leveraging the www.Hippocampome.org knowledge base, we derive local connection parameters between distinct pairs of morphologically identified neuron types based on their axonal-dendritic overlap within every layer and subregion of the hippocampal formation. Specifically, we adapt modern image analysis technology to determine the parcel-specific neurite lengths of every neuron type from representative morphologic reconstructions obtained from either sex. We then compute the average number of synapses per neuron pair using relevant anatomic volumes from the mouse brain atlas and ultrastructurally established interaction distances. Hence, we estimate connection probabilities and number of contacts for >1900 neuron type pairs, increasing the available quantitative assessments more than 11-fold. Connectivity statistics thus remain unknown for only a minority of potential synapses in the hippocampal formation, including those involving long-range (23%) or perisomatic (6%) connections and neuron types without morphologic tracings (7%). The described approach also yields approximate measurements of synaptic distances from the soma along the dendritic and axonal paths, which may affect signal attenuation and delay. Overall, this dataset fills a substantial gap in quantitatively describing hippocampal circuits and provides useful model specifications for biologically realistic neural network simulations, until further direct experimental data become available.SIGNIFICANCE STATEMENT The hippocampal formation is a crucial functional substrate for episodic memory and spatial representation. Characterizing the complex neuron type circuit of this brain region is thus important to understand the cellular mechanisms of learning and navigation. Here we present the first numerical estimates of connection probabilities, numbers of contacts per connected pair, and synaptic distances from the soma along the axonal and dendritic paths, for more than 1900 distinct neuron type pairs throughout the dentate gyrus, CA3, CA2, CA1, subiculum, and entorhinal cortex. This comprehensive dataset, publicly released online at www.Hippocampome.org, constitutes an unprecedented quantification of the majority of the local synaptic circuit for a prominent mammalian neural system and provides an essential foundation for data-driven, anatomically realistic neural network models.
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31
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Geiller T, Vancura B, Terada S, Troullinou E, Chavlis S, Tsagkatakis G, Tsakalides P, Ócsai K, Poirazi P, Rózsa BJ, Losonczy A. Large-Scale 3D Two-Photon Imaging of Molecularly Identified CA1 Interneuron Dynamics in Behaving Mice. Neuron 2020; 108:968-983.e9. [PMID: 33022227 PMCID: PMC7736348 DOI: 10.1016/j.neuron.2020.09.013] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 07/16/2020] [Accepted: 09/08/2020] [Indexed: 01/26/2023]
Abstract
Cortical computations are critically reliant on their local circuit, GABAergic cells. In the hippocampus, a large body of work has identified an unprecedented diversity of GABAergic interneurons with pronounced anatomical, molecular, and physiological differences. Yet little is known about the functional properties and activity dynamics of the major hippocampal interneuron classes in behaving animals. Here we use fast, targeted, three-dimensional (3D) two-photon calcium imaging coupled with immunohistochemistry-based molecular identification to retrospectively map in vivo activity onto multiple classes of interneurons in the mouse hippocampal area CA1 during head-fixed exploration and goal-directed learning. We find examples of preferential subtype recruitment with quantitative differences in response properties and feature selectivity during key behavioral tasks and states. These results provide new insights into the collective organization of local inhibitory circuits supporting navigational and mnemonic functions of the hippocampus.
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Affiliation(s)
- Tristan Geiller
- Department of Neuroscience, Columbia University, New York, NY, USA
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
| | - Bert Vancura
- Department of Neuroscience, Columbia University, New York, NY, USA
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
| | - Satoshi Terada
- Department of Neuroscience, Columbia University, New York, NY, USA
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
| | - Eirini Troullinou
- Institute of Computer Science, Foundation for Research and Technology Hellas, Heraklion, 70013, Greece
- Department of Computer Science, University of Crete, Heraklion, 70013, Greece
| | - Spyridon Chavlis
- Institute of Molecular Biology and Biotechnology (IMBB), Foundation for Research and Technology-Hellas (FORTH), Heraklion, Crete, 700 13, Greece
| | | | - Panagiotis Tsakalides
- Institute of Computer Science, Foundation for Research and Technology Hellas, Heraklion, 70013, Greece
- Department of Computer Science, University of Crete, Heraklion, 70013, Greece
| | - Katalin Ócsai
- Faculty of Information Technology, Pázmány Péter University, Budapest
| | - Panayiota Poirazi
- Institute of Molecular Biology and Biotechnology (IMBB), Foundation for Research and Technology-Hellas (FORTH), Heraklion, Crete, 700 13, Greece
| | - Balázs J Rózsa
- Faculty of Information Technology, Pázmány Péter University, Budapest
- Laboratory of 3D Functional Network and Dendritic Imaging, Institute of Experimental Medicine, Hungarian Academy of Sciences, Eötvös Loránd Research Network, Budapest, Hungary
| | - Attila Losonczy
- Department of Neuroscience, Columbia University, New York, NY, USA
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
- The Kavli Institute for Brain Science, Columbia University, New York, NY, USA
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Bocchio M, Gouny C, Angulo-Garcia D, Toulat T, Tressard T, Quiroli E, Baude A, Cossart R. Hippocampal hub neurons maintain distinct connectivity throughout their lifetime. Nat Commun 2020; 11:4559. [PMID: 32917906 PMCID: PMC7486410 DOI: 10.1038/s41467-020-18432-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 08/20/2020] [Indexed: 12/13/2022] Open
Abstract
The temporal embryonic origins of cortical GABA neurons are critical for their specialization. In the neonatal hippocampus, GABA cells born the earliest (ebGABAs) operate as ‘hubs’ by orchestrating population synchrony. However, their adult fate remains largely unknown. To fill this gap, we have examined CA1 ebGABAs using a combination of electrophysiology, neurochemical analysis, optogenetic connectivity mapping as well as ex vivo and in vivo calcium imaging. We show that CA1 ebGABAs not only operate as hubs during development, but also maintain distinct morpho-physiological and connectivity profiles, including a bias for long-range targets and local excitatory inputs. In vivo, ebGABAs are activated during locomotion, correlate with CA1 cell assemblies and display high functional connectivity. Hence, ebGABAs are specified from birth to ensure unique functions throughout their lifetime. In the adult brain, this may take the form of a long-range hub role through the coordination of cell assemblies across distant regions. In the neonatal hippocampus, GABA cells born the earliest operate as ‘hubs’ by orchestrating population synchrony. Here, the authors show that the earliest born GABAergic cells in the hippocampal CA1 region maintain distinct anatomical and functional properties throughout their lifetime.
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Affiliation(s)
- Marco Bocchio
- INMED (INSERM U1249), Aix-Marseille University, Turing Center for Living Systems (CENTURI), Parc Scientifique de Luminy, 13273, Marseille, France.
| | - Claire Gouny
- INMED (INSERM U1249), Aix-Marseille University, Turing Center for Living Systems (CENTURI), Parc Scientifique de Luminy, 13273, Marseille, France
| | - David Angulo-Garcia
- INMED (INSERM U1249), Aix-Marseille University, Turing Center for Living Systems (CENTURI), Parc Scientifique de Luminy, 13273, Marseille, France.,Grupo de Modelado Computacional-Dinámica y Complejidad de Sistemas, Instituto de Matemáticas Aplicadas, Universidad de Cartagena, 130001, Cartagena, Colombia
| | - Tom Toulat
- INMED (INSERM U1249), Aix-Marseille University, Turing Center for Living Systems (CENTURI), Parc Scientifique de Luminy, 13273, Marseille, France
| | - Thomas Tressard
- INMED (INSERM U1249), Aix-Marseille University, Turing Center for Living Systems (CENTURI), Parc Scientifique de Luminy, 13273, Marseille, France
| | - Eleonora Quiroli
- INMED (INSERM U1249), Aix-Marseille University, Turing Center for Living Systems (CENTURI), Parc Scientifique de Luminy, 13273, Marseille, France
| | - Agnès Baude
- INMED (INSERM U1249), Aix-Marseille University, Turing Center for Living Systems (CENTURI), Parc Scientifique de Luminy, 13273, Marseille, France
| | - Rosa Cossart
- INMED (INSERM U1249), Aix-Marseille University, Turing Center for Living Systems (CENTURI), Parc Scientifique de Luminy, 13273, Marseille, France.
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Mueller M, Egger V. Dendritic integration in olfactory bulb granule cells upon simultaneous multispine activation: Low thresholds for nonlocal spiking activity. PLoS Biol 2020; 18:e3000873. [PMID: 32966273 PMCID: PMC7535128 DOI: 10.1371/journal.pbio.3000873] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 10/05/2020] [Accepted: 08/24/2020] [Indexed: 11/18/2022] Open
Abstract
The inhibitory axonless olfactory bulb granule cells form reciprocal dendrodendritic synapses with mitral and tufted cells via large spines, mediating recurrent and lateral inhibition. As a case in point for dendritic transmitter release, rat granule cell dendrites are highly excitable, featuring local Na+ spine spikes and global Ca2+- and Na+-spikes. To investigate the transition from local to global signaling, we performed holographic, simultaneous 2-photon uncaging of glutamate at up to 12 granule cell spines, along with whole-cell recording and dendritic 2-photon Ca2+ imaging in acute juvenile rat brain slices. Coactivation of less than 10 reciprocal spines was sufficient to generate diverse regenerative signals that included regional dendritic Ca2+-spikes and dendritic Na+-spikes (D-spikes). Global Na+-spikes could be triggered in one third of granule cells. Individual spines and dendritic segments sensed the respective signal transitions as increments in Ca2+ entry. Dendritic integration as monitored by the somatic membrane potential was mostly linear until a threshold number of spines was activated, at which often D-spikes along with supralinear summation set in. As to the mechanisms supporting active integration, NMDA receptors (NMDARs) strongly contributed to all aspects of supralinearity, followed by dendritic voltage-gated Na+- and Ca2+-channels, whereas local Na+ spine spikes, as well as morphological variables, barely mattered. Because of the low numbers of coactive spines required to trigger dendritic Ca2+ signals and thus possibly lateral release of GABA onto mitral and tufted cells, we predict that thresholds for granule cell-mediated bulbar lateral inhibition are low. Moreover, D-spikes could provide a plausible substrate for granule cell-mediated gamma oscillations.
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Affiliation(s)
- Max Mueller
- Neurophysiology, Institute of Zoology, Universität Regensburg, Regensburg, Germany
| | - Veronica Egger
- Neurophysiology, Institute of Zoology, Universität Regensburg, Regensburg, Germany
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Sos KE, Mayer MI, Takács VT, Major A, Bardóczi Z, Beres BM, Szeles T, Saito T, Saido TC, Mody I, Freund TF, Nyiri G. Amyloid β induces interneuron-specific changes in the hippocampus of APPNL-F mice. PLoS One 2020; 15:e0233700. [PMID: 32469963 PMCID: PMC7259556 DOI: 10.1371/journal.pone.0233700] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 05/11/2020] [Indexed: 01/07/2023] Open
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder characterized by cognitive decline and amyloid-beta (Aβ) depositions generated by the proteolysis of amyloid precursor protein (APP) in the brain. In APPNL-F mice, APP gene was humanized and contains two familial AD mutations, and APP-unlike other mouse models of AD-is driven by the endogenous mouse APP promoter. Similar to people without apparent cognitive dysfunction but with heavy Aβ plaque load, we found no significant decline in the working memory of adult APPNL-F mice, but these mice showed decline in the expression of normal anxiety. Using immunohistochemistry and 3D block-face scanning electron microscopy, we found no changes in GABAA receptor positivity and size of somatic and dendritic synapses of hippocampal interneurons. We did not find alterations in the level of expression of perineuronal nets around parvalbumin (PV) interneurons or in the density of PV- or somatostatin-positive hippocampal interneurons. However, in contrast to other investigated cell types, PV interneuron axons were occasionally mildly dystrophic around Aβ plaques, and the synapses of PV-positive axon initial segment (AIS)-targeting interneurons were significantly enlarged. Our results suggest that PV interneurons are highly resistant to amyloidosis in APPNL-F mice and amyloid-induced increase in hippocampal pyramidal cell excitability may be compensated by PV-positive AIS-targeting cells. Mechanisms that make PV neurons more resilient could therefore be exploited in the treatment of AD for mitigating Aβ-related inflammatory effects on neurons.
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Affiliation(s)
- Katalin E. Sos
- Department of Cellular and Network Neurobiology, Institute of Experimental Medicine, HAS, Budapest, Hungary
- János Szentágothai Doctoral School of Neurosciences, Semmelweis University, Budapest, Hungary
| | - Márton I. Mayer
- Department of Cellular and Network Neurobiology, Institute of Experimental Medicine, HAS, Budapest, Hungary
- János Szentágothai Doctoral School of Neurosciences, Semmelweis University, Budapest, Hungary
| | - Virág T. Takács
- Department of Cellular and Network Neurobiology, Institute of Experimental Medicine, HAS, Budapest, Hungary
| | - Abel Major
- Department of Cellular and Network Neurobiology, Institute of Experimental Medicine, HAS, Budapest, Hungary
| | - Zsuzsanna Bardóczi
- Department of Cellular and Network Neurobiology, Institute of Experimental Medicine, HAS, Budapest, Hungary
| | - Barnabas M. Beres
- Department of Cellular and Network Neurobiology, Institute of Experimental Medicine, HAS, Budapest, Hungary
| | - Tamás Szeles
- Department of Cellular and Network Neurobiology, Institute of Experimental Medicine, HAS, Budapest, Hungary
| | - Takashi Saito
- Laboratory for Proteolytic Neuroscience, RIKEN, Center for Brain Science, Saitama, Japan
- Department of Neurocognitive Science, Nagoya City University Graduate School of Medical Science, Aichi, Japan
| | - Takaomi C. Saido
- Laboratory for Proteolytic Neuroscience, RIKEN, Center for Brain Science, Saitama, Japan
| | - István Mody
- Department of Neurology, University of California, Los Angeles, California, United States of America
| | - Tamás F. Freund
- Department of Cellular and Network Neurobiology, Institute of Experimental Medicine, HAS, Budapest, Hungary
| | - Gábor Nyiri
- Department of Cellular and Network Neurobiology, Institute of Experimental Medicine, HAS, Budapest, Hungary
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35
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McKenzie S, Nitzan N, English DF. Mechanisms of neural organization and rhythmogenesis during hippocampal and cortical ripples. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190237. [PMID: 32248777 PMCID: PMC7209923 DOI: 10.1098/rstb.2019.0237] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/26/2019] [Indexed: 12/19/2022] Open
Abstract
Neural activity during ripples has attracted great theoretical and experimental attention over the last three decades. Perhaps one reason for such interest is that ripples occur during quiet waking moments and during sleep, times when we reflect and dream about what has just occurred and what we expect to happen next. The hope is that understanding such 'offline' activity may yield insights into reflection, planning, and the purposes of sleep. This review focuses on the mechanisms by which neurons organize during these high-frequency events. In studying ripples, broader principles have emerged that relate intrinsic neural properties, network topology and synaptic plasticity in controlling neural activity. Ripples, therefore, serve as an excellent model for studying how properties of a neural network relate to neural dynamics. This article is part of the Theo Murphy meeting issue 'Memory reactivation: replaying events past, present and future'.
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Affiliation(s)
- Sam McKenzie
- NYULMC Neuroscience Institute, New York, NY, USA
| | - Noam Nitzan
- Neuroscience Research Center NWFZ, Berlin, Germany
| | - Daniel F. English
- Virginia Tech School of Neuroscience Blacksburg, Blacksburg, VA, USA
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36
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Kumar M, Deshmukh SS. Differential propagation of ripples along the proximodistal and septotemporal axes of dorsal CA1 of rats. Hippocampus 2020; 30:970-986. [PMID: 32386276 DOI: 10.1002/hipo.23211] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2019] [Revised: 03/15/2020] [Accepted: 04/09/2020] [Indexed: 11/10/2022]
Abstract
The functional connectivity of the hippocampus with its primary cortical input, the entorhinal cortex, is organized topographically. In area CA1 of the hippocampus, this leads to different functional gradients along the proximodistal and septotemporal axes of spatial/sensory responsivity and spatial resolution respectively. CA1 ripples, a network phenomenon, allow us to test whether the hippocampal neural network shows corresponding gradients in functional connectivity along the two axes. We studied the occurrence and propagation of ripples across the entire proximodistal axis along with a comparable spatial range of the septotemporal axis of dorsal CA1. We observed that ripples could occur at any location, and their amplitudes were independent of the tetrode location along the proximodistal and septotemporal axes. When a ripple was detected on a particular tetrode ("reference tetrode"), however, the probability of cooccurrence of ripples and ripple amplitude observed on the other tetrodes decreased as a function of distance from the reference tetrode. This reduction was greater along the proximodistal axis than the septotemporal axis. Furthermore, we found that ripples propagate primarily along the proximodistal axis. Thus, over a spatial scale of ∼1.5 mm, the network is anisotropic along the two axes, complementing the topographically organized cortico-hippocampal connections.
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Affiliation(s)
- Mekhala Kumar
- Centre for Neuroscience, Indian Institute of Science, Bangalore, Karnataka, India
| | - Sachin S Deshmukh
- Centre for Neuroscience, Indian Institute of Science, Bangalore, Karnataka, India
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37
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Flossmann T, Kaas T, Rahmati V, Kiebel SJ, Witte OW, Holthoff K, Kirmse K. Somatostatin Interneurons Promote Neuronal Synchrony in the Neonatal Hippocampus. Cell Rep 2020; 26:3173-3182.e5. [PMID: 30893591 DOI: 10.1016/j.celrep.2019.02.061] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 12/18/2018] [Accepted: 02/13/2019] [Indexed: 01/31/2023] Open
Abstract
Synchronized activity is a universal characteristic of immature neural circuits that is essential for their developmental refinement and strongly depends on GABAergic neurotransmission. A major subpopulation of GABA-releasing interneurons (INs) expresses somatostatin (SOM) and proved critical for rhythm generation in adulthood. Here, we report a mechanism whereby SOM INs promote neuronal synchrony in the neonatal CA1 region. Combining imaging and electrophysiological approaches, we demonstrate that SOM INs and pyramidal cells (PCs) coactivate during spontaneous activity. Bidirectional optogenetic manipulations reveal excitatory GABAergic outputs to PCs that evoke correlated network events in an NKCC1-dependent manner and contribute to spontaneous synchrony. Using a dynamic systems modeling approach, we show that SOM INs affect network dynamics through a modulation of network instability and amplification threshold. Our study identifies a network function of SOM INs with implications for the activity-dependent construction of developing brain circuits.
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Affiliation(s)
- Tom Flossmann
- Hans-Berger Department of Neurology, Jena University Hospital, 07747 Jena, Germany
| | - Thomas Kaas
- Hans-Berger Department of Neurology, Jena University Hospital, 07747 Jena, Germany
| | - Vahid Rahmati
- Department of Psychology, Technische Universität Dresden, 01187 Dresden, Germany
| | - Stefan J Kiebel
- Department of Psychology, Technische Universität Dresden, 01187 Dresden, Germany
| | - Otto W Witte
- Hans-Berger Department of Neurology, Jena University Hospital, 07747 Jena, Germany
| | - Knut Holthoff
- Hans-Berger Department of Neurology, Jena University Hospital, 07747 Jena, Germany
| | - Knut Kirmse
- Hans-Berger Department of Neurology, Jena University Hospital, 07747 Jena, Germany.
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38
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Dissociation of somatostatin and parvalbumin interneurons circuit dysfunctions underlying hippocampal theta and gamma oscillations impaired by amyloid β oligomers in vivo. Brain Struct Funct 2020; 225:935-954. [PMID: 32107637 PMCID: PMC7166204 DOI: 10.1007/s00429-020-02044-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 02/06/2020] [Indexed: 12/18/2022]
Abstract
Accumulation of amyloid β oligomers (AβO) in Alzheimer’s disease (AD) impairs hippocampal theta and gamma oscillations. These oscillations are important in memory functions and depend on distinct subtypes of hippocampal interneurons such as somatostatin-positive (SST) and parvalbumin-positive (PV) interneurons. Here, we investigated whether AβO causes dysfunctions in SST and PV interneurons by optogenetically manipulating them during theta and gamma oscillations in vivo in AβO-injected SST-Cre or PV-Cre mice. Hippocampal in vivo multi-electrode recordings revealed that optogenetic activation of channelrhodopsin-2 (ChR2)-expressing SST and PV interneurons in AβO-injected mice selectively restored AβO-induced reduction of the peak power of theta and gamma oscillations, respectively, and resynchronized CA1 pyramidal cell (PC) spikes. Moreover, SST and PV interneuron spike phases were resynchronized relative to theta and gamma oscillations, respectively. Whole-cell voltage-clamp recordings in CA1 PC in ex vivo hippocampal slices from AβO-injected mice revealed that optogenetic activation of SST and PV interneurons enhanced spontaneous inhibitory postsynaptic currents (IPSCs) selectively at theta and gamma frequencies, respectively. Furthermore, analyses of the stimulus–response curve, paired-pulse ratio, and short-term plasticity of SST and PV interneuron-evoked IPSCs ex vivo showed that AβO increased the initial GABA release probability to depress SST/PV interneuron’s inhibitory input to CA1 PC selectively at theta and gamma frequencies, respectively. Our results reveal frequency-specific and interneuron subtype-specific presynaptic dysfunctions of SST and PV interneurons’ input to CA1 PC as the synaptic mechanisms underlying AβO-induced impairments of hippocampal network oscillations and identify them as potential therapeutic targets for restoring hippocampal network oscillations in early AD.
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Park K, Lee J, Jang HJ, Richards BA, Kohl MM, Kwag J. Optogenetic activation of parvalbumin and somatostatin interneurons selectively restores theta-nested gamma oscillations and oscillation-induced spike timing-dependent long-term potentiation impaired by amyloid β oligomers. BMC Biol 2020; 18:7. [PMID: 31937327 PMCID: PMC6961381 DOI: 10.1186/s12915-019-0732-7] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 12/16/2019] [Indexed: 12/11/2022] Open
Abstract
Background Abnormal accumulation of amyloid β1–42 oligomers (AβO1–42), a hallmark of Alzheimer’s disease, impairs hippocampal theta-nested gamma oscillations and long-term potentiation (LTP) that are believed to underlie learning and memory. Parvalbumin-positive (PV) and somatostatin-positive (SST) interneurons are critically involved in theta-nested gamma oscillogenesis and LTP induction. However, how AβO1–42 affects PV and SST interneuron circuits is unclear. Through optogenetic manipulation of PV and SST interneurons and computational modeling of the hippocampal neural circuits, we dissected the contributions of PV and SST interneuron circuit dysfunctions on AβO1–42-induced impairments of hippocampal theta-nested gamma oscillations and oscillation-induced LTP. Results Targeted whole-cell patch-clamp recordings and optogenetic manipulations of PV and SST interneurons during in vivo-like, optogenetically induced theta-nested gamma oscillations in vitro revealed that AβO1–42 causes synapse-specific dysfunction in PV and SST interneurons. AβO1–42 selectively disrupted CA1 pyramidal cells (PC)-to-PV interneuron and PV-to-PC synapses to impair theta-nested gamma oscillogenesis. In contrast, while having no effect on PC-to-SST or SST-to-PC synapses, AβO1–42 selectively disrupted SST interneuron-mediated disinhibition to CA1 PC to impair theta-nested gamma oscillation-induced spike timing-dependent LTP (tLTP). Such AβO1–42-induced impairments of gamma oscillogenesis and oscillation-induced tLTP were fully restored by optogenetic activation of PV and SST interneurons, respectively, further supporting synapse-specific dysfunctions in PV and SST interneurons. Finally, computational modeling of hippocampal neural circuits including CA1 PC, PV, and SST interneurons confirmed the experimental observations and further revealed distinct functional roles of PV and SST interneurons in theta-nested gamma oscillations and tLTP induction. Conclusions Our results reveal that AβO1–42 causes synapse-specific dysfunctions in PV and SST interneurons and that optogenetic modulations of these interneurons present potential therapeutic targets for restoring hippocampal network oscillations and synaptic plasticity impairments in Alzheimer’s disease.
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Affiliation(s)
- Kyerl Park
- Department of Brain and Cognitive Engineering, Korea University, Seoul, 02841, Republic of Korea
| | - Jaedong Lee
- Department of Brain and Cognitive Engineering, Korea University, Seoul, 02841, Republic of Korea
| | - Hyun Jae Jang
- Department of Brain and Cognitive Engineering, Korea University, Seoul, 02841, Republic of Korea
| | - Blake A Richards
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, M1C 1A4, Canada
| | - Michael M Kohl
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, UK
| | - Jeehyun Kwag
- Department of Brain and Cognitive Engineering, Korea University, Seoul, 02841, Republic of Korea.
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40
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Andreakos N, Yue S, Cutsuridis V. Recall Performance Improvement in a Bio-Inspired Model of the Mammalian Hippocampus. Brain Inform 2020. [DOI: 10.1007/978-3-030-59277-6_29] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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41
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Arriaga M, Han EB. Structured inhibitory activity dynamics in new virtual environments. eLife 2019; 8:e47611. [PMID: 31591960 PMCID: PMC6850773 DOI: 10.7554/elife.47611] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 10/05/2019] [Indexed: 12/04/2022] Open
Abstract
Inhibition plays a powerful role in regulating network excitation and plasticity; however, the activity of defined interneuron types during spatial exploration remain poorly understood. Using two-photon calcium imaging, we recorded hippocampal CA1 somatostatin- and parvalbumin-expressing interneurons as mice performed a goal-directed spatial navigation task in new visual virtual reality (VR) contexts. Activity in both interneuron classes was strongly suppressed but recovered as animals learned to adapt the previously learned task to the new spatial context. Surprisingly, although there was a range of activity suppression across the population, individual somatostatin-expressing interneurons showed consistent levels of activity modulation across exposure to multiple novel environments, suggesting context-independent, stable network roles during spatial exploration. This work reveals population-level temporally dynamic interneuron activity in new environments, within which each interneuron shows stable and consistent activity modulation.
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Affiliation(s)
- Moises Arriaga
- Department of NeuroscienceWashington University School of MedicineSt. LouisUnited States
| | - Edward B Han
- Department of NeuroscienceWashington University School of MedicineSt. LouisUnited States
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42
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Nicola W, Clopath C. A diversity of interneurons and Hebbian plasticity facilitate rapid compressible learning in the hippocampus. Nat Neurosci 2019; 22:1168-1181. [PMID: 31235906 DOI: 10.1038/s41593-019-0415-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 04/23/2019] [Indexed: 11/09/2022]
Abstract
The hippocampus is able to rapidly learn incoming information, even if that information is only observed once. Furthermore, this information can be replayed in a compressed format in either forward or reverse modes during sharp wave-ripples (SPW-Rs). We leveraged state-of-the-art techniques in training recurrent spiking networks to demonstrate how primarily interneuron networks can achieve the following: (1) generate internal theta sequences to bind externally elicited spikes in the presence of inhibition from the medial septum; (2) compress learned spike sequences in the form of a SPW-R when septal inhibition is removed; (3) generate and refine high-frequency assemblies during SPW-R-mediated compression; and (4) regulate the inter-SPW interval timing between SPW-Rs in ripple clusters. From the fast timescale of neurons to the slow timescale of behaviors, interneuron networks serve as the scaffolding for one-shot learning by replaying, reversing, refining, and regulating spike sequences.
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Affiliation(s)
- Wilten Nicola
- Department of Bioengineering, Imperial College London, London, UK
| | - Claudia Clopath
- Department of Bioengineering, Imperial College London, London, UK.
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43
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44
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Rytova V, Ganella DE, Hawkes D, Bathgate RAD, Ma S, Gundlach AL. Chronic activation of the relaxin-3 receptor on GABA neurons in rat ventral hippocampus promotes anxiety and social avoidance. Hippocampus 2019; 29:905-920. [PMID: 30891856 DOI: 10.1002/hipo.23089] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 02/19/2019] [Accepted: 02/22/2019] [Indexed: 12/24/2022]
Abstract
Anxiety disorders are highly prevalent in modern society and better treatments are required. Key brain areas and signaling systems underlying anxiety include prefrontal cortex, hippocampus, and amygdala, and monoaminergic and peptidergic systems, respectively. Hindbrain GABAergic projection neurons that express the peptide, relaxin-3, broadly innervate the forebrain, particularly the septum and hippocampus, and relaxin-3 acts via a Gi/o -protein-coupled receptor known as the relaxin-family peptide 3 receptor (RXFP3). Thus, relaxin-3/RXFP3 signaling is implicated in modulation of arousal, motivation, mood, memory, and anxiety. Ventral hippocampus (vHip) is central to affective and cognitive processing and displays a high density of relaxin-3-positive nerve fibers and RXFP3 binding sites, but the identity of target neurons and associated effects on behavior are unknown. Therefore, in adult, male rats, we assessed the neurochemical nature of hippocampal RXFP3 mRNA-expressing neurons and anxiety-like and social behavior following chronic RXFP3 activation in vHip by viral vector expression of an RXFP3-selective agonist peptide, R3/I5. RXFP3 mRNA detected by fluorescent in situ hybridization was topographically distributed across the hippocampus in somatostatin- and parvalbumin-mRNA expressing GABA neurons. Chronic RXFP3 activation in vHip increased anxiety-like behavior in the light-dark box and elevated-plus maze, but not the large open-field test, and reduced social interaction with a conspecific stranger. Our data reveal disruptive effects of persistent RXFP3 signaling on hippocampal GABA networks important in anxiety; and identify a potential therapeutic target for anxiety disorders that warrants further investigation in relevant preclinical models.
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Affiliation(s)
- Valeria Rytova
- Discovery Science, The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia.,Florey Department of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, Australia
| | - Despina E Ganella
- Discovery Science, The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - David Hawkes
- Discovery Science, The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - Ross A D Bathgate
- Discovery Science, The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia.,Department of Biochemistry and Molecular Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Sherie Ma
- Discovery Science, The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia.,Florey Department of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, Australia
| | - Andrew L Gundlach
- Discovery Science, The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia.,Florey Department of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, Australia.,Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Victoria, Australia
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45
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Lévesque M, Avoli M. High-frequency oscillations and focal seizures in epileptic rodents. Neurobiol Dis 2018; 124:396-407. [PMID: 30590178 DOI: 10.1016/j.nbd.2018.12.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 11/26/2018] [Accepted: 12/22/2018] [Indexed: 01/09/2023] Open
Abstract
High-pass filtering (> 80 Hz) of EEG signals has enabled neuroscientists to analyze high-frequency oscillations (HFOs; i.e., ripples: 80-200 Hz and fast ripples: 250-500 Hz) in epileptic patients presenting with focal seizures and in animal models mimicking this condition. Evidence obtained from these studies indicate that HFOs mirror pathological network activity that may initiate and sustain ictogenesis and epileptogenesis. HFOs are observed in temporal lobe regions of epileptic animals during interictal periods but they also occur before seizure onset and during the ictal period, suggesting that they can pinpoint to the mechanisms of seizure generation. Accordingly, ripples and fast ripples predominate during two specific seizure onset patterns termed low-voltage fast and hypersynchronous, respectively. In this review we will: (i) summarize these experimental studies; (ii) consider the evolution of HFOs over time during epileptogenesis; (iii) address data obtained with optogenetic stimulating procedures both in vitro and in vivo, and (iv) take into account the impact of anti-epileptic drugs on HFOs. We expect these findings to contribute to understanding the neuronal mechanisms leading to ictogenesis and epileptogenesis thus leading to the development of mechanistically targeted anti-epileptic strategies.
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Affiliation(s)
| | - Massimo Avoli
- Montreal Neurological Institute, Canada; Departments of Neurology & Neurosurgery, and of Physiology, McGill University, Montréal, H3A 2B4 Québec, Canada; Department of Experimental Medicine, Facoltà di Medicina e Odontoiatria, Sapienza University of Rome, 00185 Roma, Italy
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46
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Francavilla R, Villette V, Luo X, Chamberland S, Muñoz-Pino E, Camiré O, Wagner K, Kis V, Somogyi P, Topolnik L. Connectivity and network state-dependent recruitment of long-range VIP-GABAergic neurons in the mouse hippocampus. Nat Commun 2018; 9:5043. [PMID: 30487571 PMCID: PMC6261953 DOI: 10.1038/s41467-018-07162-5] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 10/18/2018] [Indexed: 11/21/2022] Open
Abstract
GABAergic interneurons in the hippocampus provide for local and long-distance coordination of neurons in functionally connected areas. Vasoactive intestinal peptide-expressing (VIP+) interneurons occupy a distinct niche in circuitry as many of them specialize in innervating GABAergic cells, thus providing network disinhibition. In the CA1 hippocampus, VIP+ interneuron-selective cells target local interneurons. Here, we discover a type of VIP+ neuron whose axon innervates CA1 and also projects to the subiculum (VIP-LRPs). VIP-LRPs show specific molecular properties and target interneurons within the CA1 area but both interneurons and pyramidal cells within subiculum. They are interconnected through gap junctions but demonstrate sparse spike coupling in vitro. In awake mice, VIP-LRPs decrease their activity during theta-run epochs and are more active during quiet wakefulness but not coupled to sharp-wave ripples. Together, the data provide evidence for VIP interneuron molecular diversity and functional specialization in controlling cell ensembles along the hippocampo-subicular axis.
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Affiliation(s)
- Ruggiero Francavilla
- Neuroscience Axis, CHU de Québec Research Center, Université Laval, Quebec, QC, G1V 4G2, Canada
- Department of Biochemistry, Microbiology and Bio-informatics, Université Laval, Quebec, QC, G1V 0A6, Canada
| | - Vincent Villette
- Neuroscience Axis, CHU de Québec Research Center, Université Laval, Quebec, QC, G1V 4G2, Canada
- Department of Biochemistry, Microbiology and Bio-informatics, Université Laval, Quebec, QC, G1V 0A6, Canada
| | - Xiao Luo
- Neuroscience Axis, CHU de Québec Research Center, Université Laval, Quebec, QC, G1V 4G2, Canada
- Department of Biochemistry, Microbiology and Bio-informatics, Université Laval, Quebec, QC, G1V 0A6, Canada
| | - Simon Chamberland
- Department of Biochemistry, Microbiology and Bio-informatics, Université Laval, Quebec, QC, G1V 0A6, Canada
| | - Einer Muñoz-Pino
- Neuroscience Axis, CHU de Québec Research Center, Université Laval, Quebec, QC, G1V 4G2, Canada
- Department of Biochemistry, Microbiology and Bio-informatics, Université Laval, Quebec, QC, G1V 0A6, Canada
| | - Olivier Camiré
- Neuroscience Axis, CHU de Québec Research Center, Université Laval, Quebec, QC, G1V 4G2, Canada
- Department of Biochemistry, Microbiology and Bio-informatics, Université Laval, Quebec, QC, G1V 0A6, Canada
| | - Kristina Wagner
- Department of Pharmacology, Oxford University, Oxford, OX1 3QT, UK
| | - Viktor Kis
- Department of Pharmacology, Oxford University, Oxford, OX1 3QT, UK
| | - Peter Somogyi
- Department of Pharmacology, Oxford University, Oxford, OX1 3QT, UK
| | - Lisa Topolnik
- Neuroscience Axis, CHU de Québec Research Center, Université Laval, Quebec, QC, G1V 4G2, Canada.
- Department of Biochemistry, Microbiology and Bio-informatics, Université Laval, Quebec, QC, G1V 0A6, Canada.
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47
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Hussin AT, Leonard TK, Hoffman KL. Sharp-wave ripple features in macaques depend on behavioral state and cell-type specific firing. Hippocampus 2018; 30:50-59. [PMID: 30371963 PMCID: PMC7004038 DOI: 10.1002/hipo.23046] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 09/24/2018] [Accepted: 10/17/2018] [Indexed: 12/20/2022]
Abstract
Sharp-wave ripples (SWRs) are spontaneous, synchronized neural population events in the hippocampus widely thought to play a role in memory consolidation and retrieval. They occur predominantly in sleep and quiet immobility, and in primates, they also appear during active visual exploration. Typical measures of SWRs in behaving rats include changes in the rate of occurrence, or in the incidence of specific neural ensemble activity contained within the categorical SWR event. Much less is known about the relevance of spatiotemporal SWR features, though they may index underlying activity of specific cell types including ensemble-specific internally generated sequences. Furthermore, changes in SWR features during active exploratory states are unknown. In this study, we recorded hippocampal local-field potentials and single-units during periods of quiescence and as macaques performed a memory-guided visual search task. We observed that (a) ripples during quiescence have greater amplitudes and larger postripple waves (PRW) compared to those in task epochs, and (b) during "remembered" trials, ripples have larger amplitudes than during "forgotten" trials, with no change in duration or PRWs. We further found that spiking activity influences SWR features as a function of cell type and ripple timing. As expected, larger ripple amplitudes were associated with putative pyramidal or putative basket interneuron (IN) activity, even when the spikes in question exceed the duration of the ripple. In contrast, the PRW was attenuated with activity from low firing rate cells and enhanced with activity from high firing rate cells, with putative IN spikes during ripples leading to the most prominent PRW peaks. The selective changes in SWR features as a function of time window, cell type, and cognitive/vigilance states suggest that this mesoscopic field event can offer additional information about the local network and animal's state than would be appreciated from SWR event rates alone.
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Affiliation(s)
- Ahmed T Hussin
- Department of Biology, Centre for Vision Research, York University, Toronto, Ontario, Canada
| | - Timothy K Leonard
- Department of Psychology, Centre for Vision Research, York University, Toronto, Ontario, Canada
| | - Kari L Hoffman
- Department of Psychology, Centre for Vision Research, York University, Toronto, Ontario, Canada.,Department of Psychology, Center for Integrative and Cognitive Neuroscience, Vanderbilt Vision Research Center, Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee
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Long-Term Potentiation and Excitability in the Hippocampus Are Modulated Differently by θ Rhythm. eNeuro 2018; 5:eN-CFN-0236-18. [PMID: 30627662 PMCID: PMC6325566 DOI: 10.1523/eneuro.0236-18.2018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 11/02/2018] [Accepted: 11/05/2018] [Indexed: 01/27/2023] Open
Abstract
Oscillations in the brain facilitate neural processing and cognitive functions. This study investigated the dependence of long-term potentiation (LTP), a neural correlate of memory, on the phase of the hippocampal θ rhythm, a prominent brain oscillation. Multichannel field potentials and current source-sinks were analyzed in hippocampal CA1 of adult male rats under urethane anesthesia. A single burst (five pulses at 200 Hz) stimulation of stratum oriens (OR) induced LTP of the basal dendritic excitatory sink (ES), which was maximal when the burst was delivered at ∼340° and ∼160° of the distal dendritic θ rhythm. Apical dendritic sink evoked by stratum radiatum (RAD) stimulation also showed biphasic maxima at ∼30° and ∼210° of the distal dendritic θ rhythm, about 50° phase delay to basal dendritic LTP. By contrast, maximal population spike (PS) excitability, following single-pulse excitation of the basal or mid-apical dendrites, occurred at a θ phase of ∼140°, and maximal basal dendritic ES occurred at ∼20°; γ (30–57 Hz) activity recorded in CA1 RAD had maximal power at ∼300° of the distal dendritic θ rhythm, different from the phases of maximal LTP. LTP induced during the rising θ phase was NMDA receptor sensitive. It is suggested that the θ phase modulation of CA1 PS excitability is mainly provided by θ-rhythmic proximal inhibition, while dendritic LTP is also modulated by dendritic inhibition and excitation, specific to basal and apical dendrites. In summary, basal and apical dendritic synaptic plasticity and spike excitability are facilitated at different θ phases in a compartmental fashion.
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49
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Hyper-diversity of CRH interneurons in mouse hippocampus. Brain Struct Funct 2018; 224:583-598. [PMID: 30456559 DOI: 10.1007/s00429-018-1793-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 11/09/2018] [Indexed: 12/20/2022]
Abstract
Hippocampal inhibitory interneurons comprise an anatomically, neurochemically and electrophysiologically diverse population of cells that are essential for the generation of the oscillatory activity underlying hippocampal spatial and episodic memory processes. Here, we aimed to characterize a population of interneurons that express the stress-related neuropeptide corticotropin-releasing hormone (CRH) within existing interneuronal categories through the use of combined electrophysiological and immunocytochemical approaches. Focusing on CA1 strata pyramidale and radiatum of mouse hippocampus, CRH interneurons were found to exhibit a heterogeneous neurochemical phenotype with parvalbumin, cholecystokinin and calretinin co-expression observed to varying degrees. In contrast, CRH and somatostatin were never co-expressed. Electrophysiological categorization identified heterogeneous firing pattern of CRH neurons, with two distinct subtypes within stratum pyramidale and stratum radiatum. Together, these findings indicate that CRH-expressing interneurons do not segregate into any single distinct subtype of interneuron using conventional criteria. Rather our findings suggest that CRH is likely co-expressed in subpopulations of previously described hippocampal interneurons. In addition, the observed heterogeneity suggests that distinct CRH interneuron subtypes may have specific functional roles in the both physiological and pathophysiological hippocampal processes.
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Altered hippocampal gene expression and structure in transgenic mice overexpressing neuregulin 1 (Nrg1) type I. Transl Psychiatry 2018; 8:229. [PMID: 30348978 PMCID: PMC6197224 DOI: 10.1038/s41398-018-0288-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 08/24/2018] [Accepted: 09/26/2018] [Indexed: 11/26/2022] Open
Abstract
Transgenic mice overexpressing the type I isoform of neuregulin 1 (Nrg1; NRG1) have alterations in hippocampal gamma oscillations and an age-emergent deficit in hippocampus-dependent spatial working memory. Here, we examined the molecular and morphological correlates of these findings. Microarrays showed over 100 hippocampal transcripts differentially expressed in Nrg1tg-type I mice, with enrichment of genes related to neuromodulation and, in older mice, of genes involved in inflammation and immunity. Nrg1tg-type I mice had an enlarged hippocampus with a widened dentate gyrus. The results show that Nrg1 type I impacts on hippocampal gene expression and structure in a multifaceted and partly age-related way, complementing the evidence implicating Nrg1 signaling in aspects of hippocampal function. The findings are also relevant to the possible role of NRG1 signaling in the pathophysiology of schizophrenia or other disorders affecting this brain region.
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