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Zouridis IS, Balsamo G, Preston-Ferrer P, Burgalossi A. Anatomical and electrophysiological analysis of the fasciola cinerea of the mouse hippocampus. Hippocampus 2024. [PMID: 39105449 DOI: 10.1002/hipo.23623] [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: 06/13/2023] [Revised: 05/20/2024] [Accepted: 07/03/2024] [Indexed: 08/07/2024]
Abstract
The hippocampus is considered essential for several forms of declarative memory, including spatial and social memory. Despite the extensive research of the classic subfields of the hippocampus, the fasciola cinerea (FC)-a medially located structure within the hippocampal formation-has remained largely unexplored. In the present study, we performed a morpho-functional characterization of principal neurons in the mouse FC. Using in vivo juxtacellular recording of single neurons, we found that FC neurons are distinct from neighboring CA1 pyramidal cells, both morphologically and electrophysiologically. Specifically, FC neurons displayed non-pyramidal morphology and granule cell-like apical dendrites. Compared to neighboring CA1 pyramidal neurons, FC neurons exhibited more regular in vivo firing patterns and a lower tendency to fire spikes at short interspike intervals. Furthermore, tracing experiments revealed that the FC receives inputs from the lateral but not the medial entorhinal cortex and CA3, and it provides a major intra-hippocampal projection to the septal CA2 and sparser inputs to the distal CA1. Overall, our results indicate that the FC is a morphologically and electrophysiologically distinct subfield of the hippocampal formation; given the established role of CA2 in social memory and seizure initiation, the unique efferent intra-hippocampal connectivity of the FC points to possible roles in social cognition and temporal lobe epilepsy.
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Affiliation(s)
- Ioannis S Zouridis
- Institute of Neurobiology, Eberhard Karls University of Tübingen, Tübingen, Germany
- Werner-Reichardt Centre for Integrative Neuroscience, University of Tübingen, Tübingen, Germany
- Graduate Training Centre of Neuroscience-International Max-Planck Research School (IMPRS), Tübingen, Germany
| | - Giuseppe Balsamo
- Institute of Neurobiology, Eberhard Karls University of Tübingen, Tübingen, Germany
- Werner-Reichardt Centre for Integrative Neuroscience, University of Tübingen, Tübingen, Germany
- Graduate Training Centre of Neuroscience-International Max-Planck Research School (IMPRS), Tübingen, Germany
| | - Patricia Preston-Ferrer
- Institute of Neurobiology, Eberhard Karls University of Tübingen, Tübingen, Germany
- Werner-Reichardt Centre for Integrative Neuroscience, University of Tübingen, Tübingen, Germany
| | - Andrea Burgalossi
- Institute of Neurobiology, Eberhard Karls University of Tübingen, Tübingen, Germany
- Werner-Reichardt Centre for Integrative Neuroscience, University of Tübingen, Tübingen, Germany
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2
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Pizzarelli R, Pimpinella D, Jacobs C, Tartacca A, Kullolli U, Monyer H, Alberini CM, Griguoli M. Insulin-like growth factor 2 (IGF-2) rescues social deficits in NLG3 -/y mouse model of ASDs. Front Cell Neurosci 2024; 17:1332179. [PMID: 38298376 PMCID: PMC10827848 DOI: 10.3389/fncel.2023.1332179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Accepted: 12/18/2023] [Indexed: 02/02/2024] Open
Abstract
Autism spectrum disorders (ASDs) comprise developmental disabilities characterized by impairments of social interaction and repetitive behavior, often associated with cognitive deficits. There is no current treatment that can ameliorate most of the ASDs symptomatology; thus, identifying novel therapies is urgently needed. Here, we used the Neuroligin 3 knockout mouse (NLG3-/y), a model that recapitulates the social deficits reported in ASDs patients, to test the effects of systemic administration of IGF-2, a polypeptide that crosses the blood-brain barrier and acts as a cognitive enhancer. We show that systemic IGF-2 treatment reverses the typical defects in social interaction and social novelty discrimination reflective of ASDs-like phenotypes. This effect was not accompanied by any change in spontaneous glutamatergic synaptic transmission in CA2 hippocampal region, a mechanism found to be crucial for social novelty discrimination. However, in both NLG3+/y and NLG3-/y mice IGF-2 increased cell excitability. Although further investigation is needed to clarify the cellular and molecular mechanisms underpinning IGF-2 effect on social behavior, our findings highlight IGF-2 as a potential pharmacological tool for the treatment of social dysfunctions associated with ASDs.
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Affiliation(s)
| | | | | | | | | | - Hannah Monyer
- European Brain Research Institute (EBRI), Rome, Italy
- Department of Clinical Neurobiology at the Medical Faculty of Heidelberg University and German Cancer Research Center (DKFZ), Heidelberg, Germany
| | | | - Marilena Griguoli
- European Brain Research Institute (EBRI), Rome, Italy
- Institute of Molecular Biology and Pathology of the National Council of Research (IBPM-CNR), Rome, Italy
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3
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Pelkey KA, Vargish GA, Pellegrini LV, Calvigioni D, Chapeton J, Yuan X, Hunt S, Cummins AC, Eldridge MAG, Pickel J, Chittajallu R, Averbeck BB, Tóth K, Zaghloul K, McBain CJ. Evolutionary conservation of hippocampal mossy fiber synapse properties. Neuron 2023; 111:3802-3818.e5. [PMID: 37776852 PMCID: PMC10841147 DOI: 10.1016/j.neuron.2023.09.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 07/03/2023] [Accepted: 09/06/2023] [Indexed: 10/02/2023]
Abstract
Various specialized structural/functional properties are considered essential for contextual memory encoding by hippocampal mossy fiber (MF) synapses. Although investigated to exquisite detail in model organisms, synapses, including MFs, have undergone minimal functional interrogation in humans. To determine the translational relevance of rodent findings, we evaluated MF properties within human tissue resected to treat epilepsy. Human MFs exhibit remarkably similar hallmark features to rodents, including AMPA receptor-dominated synapses with small contributions from NMDA and kainate receptors, large dynamic range with strong frequency facilitation, NMDA receptor-independent presynaptic long-term potentiation, and strong cyclic AMP (cAMP) sensitivity of release. Array tomography confirmed the evolutionary conservation of MF ultrastructure. The astonishing congruence of rodent and human MF core features argues that the basic MF properties delineated in animal models remain critical to human MF function. Finally, a selective deficit in GABAergic inhibitory tone onto human MF postsynaptic targets suggests that unrestrained detonator excitatory drive contributes to epileptic circuit hyperexcitability.
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Affiliation(s)
- Kenneth A Pelkey
- Eunice Kennedy Shriver National Institute of Child Health and Human Development Intramural Research Program, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Geoffrey A Vargish
- Eunice Kennedy Shriver National Institute of Child Health and Human Development Intramural Research Program, National Institutes of Health, Bethesda, MD 20892, USA
| | - Leonardo V Pellegrini
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Brain and Mind Research Institute, Ottawa, ON K1H 8M5, Canada
| | - Daniela Calvigioni
- Eunice Kennedy Shriver National Institute of Child Health and Human Development Intramural Research Program, National Institutes of Health, Bethesda, MD 20892, USA
| | - Julio Chapeton
- National Institute of Neurological Disorders and Stroke Intramural Research Program, National Institutes of Health, Bethesda, MD 20892, USA
| | - Xiaoqing Yuan
- Eunice Kennedy Shriver National Institute of Child Health and Human Development Intramural Research Program, National Institutes of Health, Bethesda, MD 20892, USA
| | - Steven Hunt
- Eunice Kennedy Shriver National Institute of Child Health and Human Development Intramural Research Program, National Institutes of Health, Bethesda, MD 20892, USA
| | - Alex C Cummins
- National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
| | - Mark A G Eldridge
- National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
| | - James Pickel
- National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ramesh Chittajallu
- Eunice Kennedy Shriver National Institute of Child Health and Human Development Intramural Research Program, National Institutes of Health, Bethesda, MD 20892, USA
| | - Bruno B Averbeck
- National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
| | - Katalin Tóth
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Brain and Mind Research Institute, Ottawa, ON K1H 8M5, Canada
| | - Kareem Zaghloul
- National Institute of Neurological Disorders and Stroke Intramural Research Program, National Institutes of Health, Bethesda, MD 20892, USA
| | - Chris J McBain
- Eunice Kennedy Shriver National Institute of Child Health and Human Development Intramural Research Program, National Institutes of Health, Bethesda, MD 20892, USA.
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4
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Metcalf CS. Brake Early: RGS14 in CA2 Limits Seizures and Oxidative Stress After SE. Epilepsy Curr 2023; 23:372-374. [PMID: 38269350 PMCID: PMC10805082 DOI: 10.1177/15357597231199343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2024] Open
Abstract
RGS14 Limits Seizure-Induced Mitochondrial Oxidative Stress and Pathology in Hippocampus Harbin NH, Lustberg DJ, Hurst C, Pare J, Crotty KM, Waters AL, Yeligar SM, Smith Y, Seyfried NT, Weinschenker D, Hepler JR. Neurobiol Dis. 2023;181:106128. doi:10.1016/j.nbd.2023.106128 . PMID: 37075948 RGS14 is a complex multifunctional scaffolding protein that is highly enriched within pyramidal cells (PCs) of hippocampal area CA2. In these neurons, RGS14 suppresses glutamate-induced calcium influx and related G protein and ERK signaling in dendritic spines to restrain postsynaptic signaling and plasticity. Previous findings show that, unlike PCs of hippocampal areas CA1 and CA3, CA2 PCs are resistant to a number of neurological insults, including degeneration caused by temporal lobe epilepsy (TLE). While RGS14 is protective against peripheral injury, similar roles for RGS14 during pathological injury in hippocampus remain unexplored. Recent studies showed that area CA2 modulates hippocampal excitability, generates epileptiform activity and promotes hippocampal pathology in animal models and patients with TLE. Because RGS14 suppresses CA2 excitability and signaling, we hypothesized that RGS14 would moderate seizure behavior and early hippocampal pathology following seizure activity, possibly affording protection to CA2 PCs. Using kainic acid (KA) to induce status epilepticus (KA-SE) in mice, we show that the loss of RGS14 (RGS14 KO) accelerated onset of limbic motor seizures and mortality compared to wild type (WT) mice, and that KA-SE upregulated RGS14 protein expression in CA2 and CA1 PCs of WT. Our proteomics data show that the loss of RGS14 impacted the expression of a number of proteins at baseline and after KA-SE, many of which associated unexpectedly with mitochondrial function and oxidative stress. RGS14 was shown to localize to the mitochondria in CA2 PCs of mice and reduce mitochondrial respiration in vitro. As a readout of oxidative stress, we found that RGS14 KO dramatically increased 3-nitrotyrosine levels in CA2 PCs, which was greatly exacerbated following KA-SE and correlated with a lack of superoxide dismutase 2 (SOD2) induction. Assessing for hallmarks of seizure pathology in RGS14 KO, we unexpectedly found no differences in neuronal injury in CA2 PCs. However, we observed a striking and surprising lack of microgliosis in CA1 and CA2 of RGS14 KO compared to WT. Together, our data demonstrate a newly appreciated role for RGS14 in limiting intense seizure activity and pathology in hippocampus. Our findings are consistent with a model where RGS14 limits seizure onset and mortality and, after seizure, is upregulated to support mitochondrial function, prevent oxidative stress in CA2 PCs, and promote microglial activation in hippocampus.
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5
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Whitebirch AC, Santoro B, Barnett A, Lisgaras CP, Scharfman HE, Siegelbaum SA. Reduced Cholecystokinin-Expressing Interneuron Input Contributes to Disinhibition of the Hippocampal CA2 Region in a Mouse Model of Temporal Lobe Epilepsy. J Neurosci 2023; 43:6930-6949. [PMID: 37643861 PMCID: PMC10573827 DOI: 10.1523/jneurosci.2091-22.2023] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 08/04/2023] [Accepted: 08/15/2023] [Indexed: 08/31/2023] Open
Abstract
A significant proportion of temporal lobe epilepsy (TLE) patients experience drug-resistant seizures associated with mesial temporal sclerosis, in which there is extensive cell loss in the hippocampal CA1 and CA3 subfields, with a relative sparing of dentate gyrus granule cells and CA2 pyramidal neurons (PNs). A role for CA2 in seizure generation was suggested based on findings of a reduction in CA2 synaptic inhibition (Williamson and Spencer, 1994) and the presence of interictal-like spike activity in CA2 in resected hippocampal tissue from TLE patients (Wittner et al., 2009). We recently found that in the pilocarpine-induced status epilepticus (PILO-SE) mouse model of TLE there was an increase in CA2 intrinsic excitability associated with a loss of CA2 synaptic inhibition. Furthermore, chemogenetic silencing of CA2 significantly reduced seizure frequency, consistent with a role of CA2 in promoting seizure generation and/or propagation (Whitebirch et al., 2022). In the present study, we explored the cellular basis of this inhibitory deficit using immunohistochemical and electrophysiological approaches in PILO-SE male and female mice. We report a widespread decrease in the density of pro-cholecystokinin-immunopositive (CCK+) interneurons and a functional impairment of CCK+ interneuron-mediated inhibition of CA2 PNs. We also found a disruption in the perisomatic perineuronal net in the CA2 stratum pyramidale. Such pathologic alterations may contribute to an enhanced excitation of CA2 PNs and CA2-dependent seizure activity in the PILO-SE mouse model.SIGNIFICANCE STATEMENT Impaired synaptic inhibition in hippocampal circuits has been identified as a key feature that contributes to the emergence and propagation of seizure activity in human patients and animal models of temporal lobe epilepsy (TLE). Among the hippocampal subfields, the CA2 region is particularly resilient to seizure-associated neurodegeneration and has been suggested to play a key role in seizure activity in TLE. Here we report that perisomatic inhibition of CA2 pyramidal neurons mediated by cholecystokinin-expressing interneurons is selectively reduced in acute hippocampal slices from epileptic mice. Parvalbumin-expressing interneurons, in contrast, appear relatively conserved in epileptic mice. These findings advance our understanding of the cellular mechanisms underlying inhibitory disruption in hippocampal circuits in a mouse model of spontaneous recurring seizures.
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Affiliation(s)
- Alexander C Whitebirch
- Departments of Neuroscience and Pharmacology, Kavli Institute for Brain Science, Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University Irving Medical Center, New York, New York 10027
| | - Bina Santoro
- Departments of Neuroscience and Pharmacology, Kavli Institute for Brain Science, Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University Irving Medical Center, New York, New York 10027
| | - Anastasia Barnett
- Departments of Neuroscience and Pharmacology, Kavli Institute for Brain Science, Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University Irving Medical Center, New York, New York 10027
| | - Christos Panagiotis Lisgaras
- Department of Child & Adolescent Psychiatry, New York University Langone Health, New York, New York 10016
- Department of Neuroscience & Physiology, New York University Langone Health, New York, New York 10016
- Department of Psychiatry, New York University Langone Health, New York, New York 10016
- The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, New York 10962
| | - Helen E Scharfman
- Department of Child & Adolescent Psychiatry, New York University Langone Health, New York, New York 10016
- Department of Neuroscience & Physiology, New York University Langone Health, New York, New York 10016
- Department of Psychiatry, New York University Langone Health, New York, New York 10016
- The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, New York 10962
| | - Steven A Siegelbaum
- Departments of Neuroscience and Pharmacology, Kavli Institute for Brain Science, Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University Irving Medical Center, New York, New York 10027
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6
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Bod R, Tóth K, Essam N, Tóth EZ, Erõss L, Entz L, Bagó AG, Fabó D, Ulbert I, Wittner L. Synaptic alterations and neuronal firing in human epileptic neocortical excitatory networks. Front Synaptic Neurosci 2023; 15:1233569. [PMID: 37635750 PMCID: PMC10450510 DOI: 10.3389/fnsyn.2023.1233569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 07/25/2023] [Indexed: 08/29/2023] Open
Abstract
Epilepsy is a prevalent neurological condition, with underlying neuronal mechanisms involving hyperexcitability and hypersynchrony. Imbalance between excitatory and inhibitory circuits, as well as histological reorganization are relatively well-documented in animal models or even in the human hippocampus, but less is known about human neocortical epileptic activity. Our knowledge about changes in the excitatory signaling is especially scarce, compared to that about the inhibitory cell population. This study investigated the firing properties of single neurons in the human neocortex in vitro, during pharmacological blockade of glutamate receptors, and additionally evaluated anatomical changes in the excitatory circuit in tissue samples from epileptic and non-epileptic patients. Both epileptic and non-epileptic tissues exhibited spontaneous population activity (SPA), NMDA receptor antagonization reduced SPA recurrence only in epileptic tissue, whereas further blockade of AMPA/kainate receptors reversibly abolished SPA emergence regardless of epilepsy. Firing rates did not significantly change in excitatory principal cells and inhibitory interneurons during pharmacological experiments. Granular layer (L4) neurons showed an increased firing rate in epileptic compared to non-epileptic tissue. The burstiness of neurons remained unchanged, except for that of inhibitory cells in epileptic recordings, which decreased during blockade of glutamate receptors. Crosscorrelograms computed from single neuron discharge revealed both mono- and polysynaptic connections, particularly involving intrinsically bursting principal cells. Histological investigations found similar densities of SMI-32-immunopositive long-range projecting pyramidal cells in both groups, and shorter excitatory synaptic active zones with a higher proportion of perforated synapses in the epileptic group. These findings provide insights into epileptic modifications from the perspective of the excitatory system and highlight discrete alterations in firing patterns and synaptic structure. Our data suggest that NMDA-dependent glutamatergic signaling, as well as the excitatory synaptic machinery are perturbed in epilepsy, which might contribute to epileptic activity in the human neocortex.
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Affiliation(s)
- Réka Bod
- Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Eötvös Loránd Research Network, Budapest, Hungary
- Semmelweis University Doctoral School, Budapest, Hungary
| | - Kinga Tóth
- Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Eötvös Loránd Research Network, Budapest, Hungary
| | - Nour Essam
- Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Eötvös Loránd Research Network, Budapest, Hungary
| | - Estilla Zsófia Tóth
- Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Eötvös Loránd Research Network, Budapest, Hungary
- Semmelweis University Doctoral School, Budapest, Hungary
| | - Loránd Erõss
- National Institute of Mental Health, Neurology and Neurosurgery, Budapest, Hungary
| | - László Entz
- National Institute of Mental Health, Neurology and Neurosurgery, Budapest, Hungary
| | - Attila G. Bagó
- National Institute of Mental Health, Neurology and Neurosurgery, Budapest, Hungary
| | - Dániel Fabó
- National Institute of Mental Health, Neurology and Neurosurgery, Budapest, Hungary
| | - István Ulbert
- Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Eötvös Loránd Research Network, Budapest, Hungary
- Semmelweis University Doctoral School, Budapest, Hungary
- National Institute of Mental Health, Neurology and Neurosurgery, Budapest, Hungary
- Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary
| | - Lucia Wittner
- Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Eötvös Loránd Research Network, Budapest, Hungary
- Semmelweis University Doctoral School, Budapest, Hungary
- National Institute of Mental Health, Neurology and Neurosurgery, Budapest, Hungary
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7
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Harbin NH, Lustberg DJ, Hurst C, Pare J, Crotty KM, Waters AL, Yeligar SM, Smith Y, Seyfried NT, Weinshenker D, Hepler JR. RGS14 limits seizure-induced mitochondrial oxidative stress and pathology in hippocampus. Neurobiol Dis 2023; 181:106128. [PMID: 37075948 PMCID: PMC10259180 DOI: 10.1016/j.nbd.2023.106128] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 04/02/2023] [Accepted: 04/14/2023] [Indexed: 04/21/2023] Open
Abstract
RGS14 is a complex multifunctional scaffolding protein that is highly enriched within pyramidal cells (PCs) of hippocampal area CA2. In these neurons, RGS14 suppresses glutamate-induced calcium influx and related G protein and ERK signaling in dendritic spines to restrain postsynaptic signaling and plasticity. Previous findings show that, unlike PCs of hippocampal areas CA1 and CA3, CA2 PCs are resistant to a number of neurological insults, including degeneration caused by temporal lobe epilepsy (TLE). While RGS14 is protective against peripheral injury, similar roles for RGS14 during pathological injury in hippocampus remain unexplored. Recent studies showed that area CA2 modulates hippocampal excitability, generates epileptiform activity and promotes hippocampal pathology in animal models and patients with TLE. Because RGS14 suppresses CA2 excitability and signaling, we hypothesized that RGS14 would moderate seizure behavior and early hippocampal pathology following seizure activity, possibly affording protection to CA2 PCs. Using kainic acid (KA) to induce status epilepticus (KA-SE) in mice, we show that the loss of RGS14 (RGS14 KO) accelerated onset of limbic motor seizures and mortality compared to wild type (WT) mice, and that KA-SE upregulated RGS14 protein expression in CA2 and CA1 PCs of WT. Our proteomics data show that the loss of RGS14 impacted the expression of a number of proteins at baseline and after KA-SE, many of which associated unexpectedly with mitochondrial function and oxidative stress. RGS14 was shown to localize to the mitochondria in CA2 PCs of mice and reduce mitochondrial respiration in vitro. As a readout of oxidative stress, we found that RGS14 KO dramatically increased 3- nitrotyrosine levels in CA2 PCs, which was greatly exacerbated following KA-SE and correlated with a lack of superoxide dismutase 2 (SOD2) induction. Assessing for hallmarks of seizure pathology in RGS14 KO, we unexpectedly found no differences in neuronal injury in CA2 PCs. However, we observed a striking and surprising lack of microgliosis in CA1 and CA2 of RGS14 KO compared to WT. Together, our data demonstrate a newly appreciated role for RGS14 in limiting intense seizure activity and pathology in hippocampus. Our findings are consistent with a model where RGS14 limits seizure onset and mortality and, after seizure, is upregulated to support mitochondrial function, prevent oxidative stress in CA2 PCs, and promote microglial activation in hippocampus.
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Affiliation(s)
- N H Harbin
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, 1510 Clifton Rd, 5001 Rollins Research Ctr, Atlanta, GA 30322, United States.
| | - D J Lustberg
- Department of Human Genetics, Emory University School of Medicine, 615 Michael Street, Suite 301, Atlanta, GA 30322, United States
| | - C Hurst
- Department of Biochemistry, Emory University School of Medicine, 1510 Clifton Rd, 4001 Rollins Research Center, Atlanta, GA 30322, United States.
| | - J Pare
- Emory National Primate Research Center, Emory University, 954, Gatewood Rd NE, Atlanta, GA 30329, United States.
| | - K M Crotty
- Department of Medicine, Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Emory University, 1364 Clifton Road NE, Suite H-153, Atlanta, GA 30322, United States; Atlanta Veterans Affairs Health Care System, 1670 Clairmont Road, Decatur, GA 30033, United States.
| | - A L Waters
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, 1510 Clifton Rd, 5001 Rollins Research Ctr, Atlanta, GA 30322, United States.
| | - S M Yeligar
- Department of Medicine, Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Emory University, 1364 Clifton Road NE, Suite H-153, Atlanta, GA 30322, United States; Atlanta Veterans Affairs Health Care System, 1670 Clairmont Road, Decatur, GA 30033, United States.
| | - Y Smith
- Emory National Primate Research Center, Emory University, 954, Gatewood Rd NE, Atlanta, GA 30329, United States; Department of Neurology, Emory University School of Medicine, 12 Executive Park Dr NE, Atlanta, GA, 30322, United States.
| | - N T Seyfried
- Department of Biochemistry, Emory University School of Medicine, 1510 Clifton Rd, 4001 Rollins Research Center, Atlanta, GA 30322, United States.
| | - D Weinshenker
- Department of Human Genetics, Emory University School of Medicine, 615 Michael Street, Suite 301, Atlanta, GA 30322, United States.
| | - J R Hepler
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, 1510 Clifton Rd, 5001 Rollins Research Ctr, Atlanta, GA 30322, United States.
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8
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Oliva A, Fernandez-Ruiz A, Karaba LA. CA2 orchestrates hippocampal network dynamics. Hippocampus 2023; 33:241-251. [PMID: 36575880 PMCID: PMC9974898 DOI: 10.1002/hipo.23495] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 11/25/2022] [Accepted: 12/11/2022] [Indexed: 12/29/2022]
Abstract
The hippocampus is composed of various subregions: CA1, CA2, CA3, and the dentate gyrus (DG). Despite the abundant hippocampal research literature, until recently, CA2 received little attention. The development of new genetic and physiological tools allowed recent studies characterizing the unique properties and functional roles of this hippocampal subregion. Despite its small size, the cellular content of CA2 is heterogeneous at the molecular and physiological levels. CA2 has been heavily implicated in social behaviors, including social memory. More generally, the mechanisms by which the hippocampus is involved in memory include the reactivation of neuronal ensembles following experience. This process is coordinated by synchronous network events known as sharp-wave ripples (SWRs). Recent evidence suggests that CA2 plays an important role in the generation of SWRs. The unique connectivity and physiological properties of CA2 pyramidal cells make this region a computational hub at the core of hippocampal information processing. Here, we review recent findings that support the role of CA2 in coordinating hippocampal network dynamics from a systems neuroscience perspective.
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Affiliation(s)
- Azahara Oliva
- Department of Neurobiology and Behavior, Cornell University, Ithaca, New York, USA
| | | | - Lindsay A Karaba
- Department of Neurobiology and Behavior, Cornell University, Ithaca, New York, USA
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9
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Harbin NH, Lustberg DJ, Hurst C, Pare JF, Crotty KM, Waters AL, Yeligar SM, Smith Y, Seyfried NT, Weinshenker D, Hepler JR. RGS14 is neuroprotective against seizure-induced mitochondrial oxidative stress and pathology in hippocampus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.01.526349. [PMID: 36778349 PMCID: PMC9915580 DOI: 10.1101/2023.02.01.526349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
RGS14 is a complex multifunctional scaffolding protein that is highly enriched within pyramidal cells (PCs) of hippocampal area CA2. There, RGS14 suppresses glutamate-induced calcium influx and related G protein and ERK signaling in dendritic spines to restrain postsynaptic signaling and plasticity. Previous findings show that, unlike PCs of hippocampal areas CA1 and CA3, CA2 PCs are resistant to a number of neurological insults, including degeneration caused by temporal lobe epilepsy (TLE). While RGS14 is protective against peripheral injury, similar roles for RGS14 during pathological injury in hippocampus remain unexplored. Recent studies show that area CA2 modulates hippocampal excitability, generates epileptiform activity and promotes hippocampal pathology in animal models and patients with TLE. Because RGS14 suppresses CA2 excitability and signaling, we hypothesized that RGS14 would moderate seizure behavior and early hippocampal pathology following seizure activity. Using kainic acid (KA) to induce status epilepticus (KA-SE) in mice, we show loss of RGS14 (RGS14 KO) accelerated onset of limbic motor seizures and mortality compared to wild type (WT) mice, and that KA-SE upregulated RGS14 protein expression in CA2 and CA1 PCs of WT. Utilizing proteomics, we saw loss of RGS14 impacted the expression of a number of proteins at baseline and after KA-SE, many of which associated unexpectedly with mitochondrial function and oxidative stress. RGS14 was shown to localize to the mitochondria in CA2 PCs of mice and reduce mitochondrial respiration in vitro . As a readout of oxidative stress, we found RGS14 KO dramatically increased 3-nitrotyrosine levels in CA2 PCs, which was greatly exacerbated following KA-SE and correlated with a lack of superoxide dismutase 2 (SOD2) induction. Assessing for hallmarks of seizure pathology in RGS14 KO, we observed worse neuronal injury in area CA3 (but none in CA2 or CA1), and a lack of microgliosis in CA1 and CA2 compared to WT. Together, our data demonstrates a newly appreciated neuroprotective role for RGS14 against intense seizure activity in hippocampus. Our findings are consistent with a model where, after seizure, RGS14 is upregulated to support mitochondrial function and prevent oxidative stress in CA2 PCs, limit seizure onset and hippocampal neuronal injury, and promote microglial activation in hippocampus.
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10
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Chloride ion dysregulation in epileptogenic neuronal networks. Neurobiol Dis 2023; 177:106000. [PMID: 36638891 DOI: 10.1016/j.nbd.2023.106000] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 12/25/2022] [Accepted: 01/09/2023] [Indexed: 01/13/2023] Open
Abstract
GABA is the major inhibitory neurotransmitter in the mature CNS. When GABAA receptors are activated the membrane potential is driven towards hyperpolarization due to chloride entry into the neuron. However, chloride ion dysregulation that alters the ionic gradient can result in depolarizing GABAergic post-synaptic potentials instead. In this review, we highlight that GABAergic inhibition prevents and restrains focal seizures but then reexamine this notion in the context of evidence that a static and/or a dynamic chloride ion dysregulation, that increases intracellular chloride ion concentrations, promotes epileptiform activity and seizures. To reconcile these findings, we hypothesize that epileptogenic pathologically interconnected neuron (PIN) microcircuits, representing a small minority of neurons, exhibit static chloride dysregulation and should exhibit depolarizing inhibitory post-synaptic potentials (IPSPs). We speculate that chloride ion dysregulation and PIN cluster activation may generate fast ripples and epileptiform spikes as well as initiate the hypersynchronous seizure onset pattern and microseizures. Also, we discuss the genetic, molecular, and cellular players important in chloride dysregulation which regulate epileptogenesis and initiate the low-voltage fast seizure onset pattern. We conclude that chloride dysregulation in neuronal networks appears to be critical for epileptogenesis and seizure genesis, but feed-back and feed-forward inhibitory GABAergic neurotransmission plays an important role in preventing and restraining seizures as well.
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11
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Lisgaras CP, Oliva A, Mckenzie S, LaFrancois J, Siegelbaum SA, Scharman HE. Hippocampal area CA2 controls seizure dynamics, interictal EEG abnormalities and social comorbidity in mouse models of temporal lobe epilepsy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.15.524149. [PMID: 36711983 PMCID: PMC9882187 DOI: 10.1101/2023.01.15.524149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Temporal lobe epilepsy (TLE) is characterized by spontaneous recurrent seizures, abnormal activity between seizures, and impaired behavior. CA2 pyramidal neurons (PNs) are potentially important because inhibiting them with a chemogenetic approach reduces seizure frequency in a mouse model of TLE. However, whether seizures could be stopped by timing inhibition just as a seizure begins is unclear. Furthermore, whether inhibition would reduce the cortical and motor manifestations of seizures are not clear. Finally, whether interictal EEG abnormalities and TLE comorbidities would be improved are unknown. Therefore, real-time optogenetic silencing of CA2 PNs during seizures, interictal activity and behavior were studied in 2 mouse models of TLE. CA2 silencing significantly reduced seizure duration and time spent in convulsive behavior. Interictal spikes and high frequency oscillations were significantly reduced, and social behavior was improved. Therefore, brief focal silencing of CA2 PNs reduces seizures, their propagation, and convulsive manifestations, improves interictal EEG, and ameliorates social comorbidities. HIGHLIGHTS Real-time CA2 silencing at the onset of seizures reduces seizure durationWhen CA2 silencing reduces seizure activity in hippocampus it also reduces cortical seizure activity and convulsive manifestations of seizuresInterictal spikes and high frequency oscillations are reduced by real-time CA2 silencingReal-time CA2 silencing of high frequency oscillations (>250Hz) rescues social memory deficits of chronic epileptic mice.
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12
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Piskorowski RA, Chevaleyre V. Hippocampal area CA2: interneuron disfunction during pathological states. Front Neural Circuits 2023; 17:1181032. [PMID: 37180763 PMCID: PMC10174260 DOI: 10.3389/fncir.2023.1181032] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 04/07/2023] [Indexed: 05/16/2023] Open
Abstract
Hippocampal area CA2 plays a critical role in social recognition memory and has unique cellular and molecular properties that distinguish it from areas CA1 and CA3. In addition to having a particularly high density of interneurons, the inhibitory transmission in this region displays two distinct forms of long-term synaptic plasticity. Early studies on human hippocampal tissue have reported unique alteration in area CA2 with several pathologies and psychiatric disorders. In this review, we present recent studies revealing changes in inhibitory transmission and plasticity of area CA2 in mouse models of multiple sclerosis, autism spectrum disorder, Alzheimer's disease, schizophrenia and the 22q11.2 deletion syndrome and propose how these changes could underly deficits in social cognition observed during these pathologies.
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Affiliation(s)
- Rebecca A. Piskorowski
- Université Paris Cité, INSERM UMRS 1266, Institute of Psychiatry and Neuroscience of Paris, GHU Paris Psychiatrie et Neurosciences, Paris, France
- Institute of Biology Paris Seine, Neuroscience Paris Seine, CNRS UMR 8246, INSERM U1130, Sorbonne Université, Paris, France
- *Correspondence: Rebecca A. Piskorowski,
| | - Vivien Chevaleyre
- Université Paris Cité, INSERM UMRS 1266, Institute of Psychiatry and Neuroscience of Paris, GHU Paris Psychiatrie et Neurosciences, Paris, France
- Institute of Biology Paris Seine, Neuroscience Paris Seine, CNRS UMR 8246, INSERM U1130, Sorbonne Université, Paris, France
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13
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Whitebirch AC, LaFrancois JJ, Jain S, Leary P, Santoro B, Siegelbaum SA, Scharfman HE. Enhanced excitability of the hippocampal CA2 region and its contribution to seizure activity in a mouse model of temporal lobe epilepsy. Neuron 2022; 110:3121-3138.e8. [PMID: 35987207 PMCID: PMC9547935 DOI: 10.1016/j.neuron.2022.07.020] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 05/26/2022] [Accepted: 07/19/2022] [Indexed: 11/25/2022]
Abstract
The hippocampal CA2 region, an area important for social memory, has been suspected to play a role in temporal lobe epilepsy (TLE) because of its resistance to degeneration observed in neighboring CA1 and CA3 regions in both humans and rodent models of TLE. However, little is known about whether alterations in CA2 properties promote seizure generation or propagation. Here, we addressed the role of CA2 using the pilocarpine-induced status epilepticus model of TLE. Ex vivo electrophysiological recordings from acute hippocampal slices revealed a set of coordinated changes that enhance CA2 PC intrinsic excitability, reduce CA2 inhibitory input, and increase CA2 excitatory output to its major CA1 synaptic target. Moreover, selective chemogenetic silencing of CA2 pyramidal cells caused a significant decrease in the frequency of spontaneous seizures measured in vivo. These findings provide the first evidence that CA2 actively contributes to TLE seizure activity and may thus be a promising therapeutic target.
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Affiliation(s)
- Alexander C Whitebirch
- Departments of Neuroscience and Pharmacology, Kavli Institute for Brain Science, Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University Irving Medical Center, New York, NY 10027, USA
| | - John J LaFrancois
- The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA
| | - Swati Jain
- The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA
| | - Paige Leary
- Department of Neuroscience and Physiology, New York University Langone Health, New York, NY 10016, USA
| | - Bina Santoro
- Departments of Neuroscience and Pharmacology, Kavli Institute for Brain Science, Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University Irving Medical Center, New York, NY 10027, USA
| | - Steven A Siegelbaum
- Departments of Neuroscience and Pharmacology, Kavli Institute for Brain Science, Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University Irving Medical Center, New York, NY 10027, USA.
| | - Helen E Scharfman
- Department of Child Psychiatry, New York University Langone Health, New York, NY 10016, USA; Department of Neuroscience and Physiology, New York University Langone Health, New York, NY 10016, USA; Department of Psychiatry, New York University Langone Health, New York, NY 10016, USA; The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA.
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14
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Hofer KT, Kandrács Á, Tóth K, Hajnal B, Bokodi V, Tóth EZ, Erőss L, Entz L, Bagó AG, Fabó D, Ulbert I, Wittner L. Bursting of excitatory cells is linked to interictal epileptic discharge generation in humans. Sci Rep 2022; 12:6280. [PMID: 35428851 PMCID: PMC9012754 DOI: 10.1038/s41598-022-10319-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 03/25/2022] [Indexed: 11/23/2022] Open
Abstract
Knowledge about the activity of single neurons is essential in understanding the mechanisms of synchrony generation, and particularly interesting if related to pathological conditions. The generation of interictal spikes—the hypersynchronous events between seizures—is linked to hyperexcitability and to bursting behaviour of neurons in animal models. To explore its cellular mechanisms in humans we investigated the activity of clustered single neurons in a human in vitro model generating both physiological and epileptiform synchronous events. We show that non-epileptic synchronous events resulted from the finely balanced firing of excitatory and inhibitory cells, which was shifted towards an enhanced excitability in epileptic tissue. In contrast, interictal-like spikes were characterised by an asymmetric overall neuronal discharge initiated by excitatory neurons with the presumptive leading role of bursting pyramidal cells, and possibly terminated by inhibitory interneurons. We found that the overall burstiness of human neocortical neurons is not necessarily related to epilepsy, but the bursting behaviour of excitatory cells comprising both intrinsic and synaptically driven bursting is clearly linked to the generation of epileptiform synchrony.
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Affiliation(s)
- Katharina T Hofer
- Institute of Cognitive Neuroscience and Psychology, Research Center for Natural Sciences, Eötvös Loránd Research Network, Magyar tudósok körútja 2., 1117, Budapest, Hungary.,Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, 1083, Budapest, Hungary.,Department of Neurobiology, School of Medicine and Institute for Medical Research Israel-Canada, The Hebrew University, 91120, Jerusalem, Israel
| | - Ágnes Kandrács
- Institute of Cognitive Neuroscience and Psychology, Research Center for Natural Sciences, Eötvös Loránd Research Network, Magyar tudósok körútja 2., 1117, Budapest, Hungary.,Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, 1083, Budapest, Hungary
| | - Kinga Tóth
- Institute of Cognitive Neuroscience and Psychology, Research Center for Natural Sciences, Eötvös Loránd Research Network, Magyar tudósok körútja 2., 1117, Budapest, Hungary
| | - Boglárka Hajnal
- National Institute of Mental Health, Neurology and Neurosurgery, 1143, Budapest, Hungary.,Semmelweis University Doctoral School, 1026, Budapest, Hungary
| | - Virág Bokodi
- National Institute of Mental Health, Neurology and Neurosurgery, 1143, Budapest, Hungary
| | - Estilla Zsófia Tóth
- Institute of Cognitive Neuroscience and Psychology, Research Center for Natural Sciences, Eötvös Loránd Research Network, Magyar tudósok körútja 2., 1117, Budapest, Hungary.,Semmelweis University Doctoral School, 1026, Budapest, Hungary
| | - Loránd Erőss
- National Institute of Mental Health, Neurology and Neurosurgery, 1143, Budapest, Hungary
| | - László Entz
- National Institute of Mental Health, Neurology and Neurosurgery, 1143, Budapest, Hungary
| | - Attila G Bagó
- National Institute of Mental Health, Neurology and Neurosurgery, 1143, Budapest, Hungary
| | - Dániel Fabó
- National Institute of Mental Health, Neurology and Neurosurgery, 1143, Budapest, Hungary
| | - István Ulbert
- Institute of Cognitive Neuroscience and Psychology, Research Center for Natural Sciences, Eötvös Loránd Research Network, Magyar tudósok körútja 2., 1117, Budapest, Hungary.,Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, 1083, Budapest, Hungary.,National Institute of Mental Health, Neurology and Neurosurgery, 1143, Budapest, Hungary
| | - Lucia Wittner
- Institute of Cognitive Neuroscience and Psychology, Research Center for Natural Sciences, Eötvös Loránd Research Network, Magyar tudósok körútja 2., 1117, Budapest, Hungary. .,Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, 1083, Budapest, Hungary. .,National Institute of Mental Health, Neurology and Neurosurgery, 1143, Budapest, Hungary.
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15
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Abstract
Neuropathological examination of the temporal lobe provides a better understanding and management of a wide spectrum of diseases. We focused on inflammatory diseases, epilepsy, and neurodegenerative diseases, and highlighted how the temporal lobe is particularly involved in those conditions. Although all these diseases are not specific or restricted to the temporal lobe, the temporal lobe is a key structure to understand their pathophysiology. The main histological lesions, immunohistochemical markers, and molecular alterations relevant for the neuropathological diagnostic reasoning are presented in relation to epidemiology, clinical presentation, and radiological findings. The inflammatory diseases section addressed infectious encephalitides and auto-immune encephalitides. The epilepsy section addressed (i) susceptibility of the temporal lobe to epileptogenesis, (ii) epilepsy-associated hippocampal sclerosis, (iii) malformations of cortical development, (iv) changes secondary to epilepsy, (v) long-term epilepsy-associated tumors, (vi) vascular malformations, and (vii) the absence of histological lesion in some epilepsy surgery samples. The neurodegenerative diseases section addressed (i) Alzheimer's disease, (ii) the spectrum of frontotemporal lobar degeneration, (iii) limbic-predominant age-related TDP-43 encephalopathy, and (iv) α-synucleinopathies. Finally, inflammatory diseases, epilepsy, and neurodegenerative diseases are considered as interdependent as some pathophysiological processes cross the boundaries of this classification.
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Affiliation(s)
- Susana Boluda
- Sorbonne Université, INSERM, CNRS, UMR S 1127, Paris Brain Institute, ICM, Paris, France; Neuropathology Department, Hôpitaux Universitaires La Pitié Salpêtrière - Charles Foix, AP-HP, Paris, France
| | - Danielle Seilhean
- Sorbonne Université, INSERM, CNRS, UMR S 1127, Paris Brain Institute, ICM, Paris, France; Neuropathology Department, Hôpitaux Universitaires La Pitié Salpêtrière - Charles Foix, AP-HP, Paris, France
| | - Franck Bielle
- Sorbonne Université, INSERM, CNRS, UMR S 1127, Paris Brain Institute, ICM, Paris, France; Neuropathology Department, Hôpitaux Universitaires La Pitié Salpêtrière - Charles Foix, AP-HP, Paris, France.
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16
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Perisomatic Inhibition and Its Relation to Epilepsy and to Synchrony Generation in the Human Neocortex. Int J Mol Sci 2021; 23:ijms23010202. [PMID: 35008628 PMCID: PMC8745731 DOI: 10.3390/ijms23010202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 12/21/2021] [Accepted: 12/22/2021] [Indexed: 11/21/2022] Open
Abstract
Inhibitory neurons innervating the perisomatic region of cortical excitatory principal cells are known to control the emergence of several physiological and pathological synchronous events, including epileptic interictal spikes. In humans, little is known about their role in synchrony generation, although their changes in epilepsy have been thoroughly investigated. This paper demonstraits how parvalbumin (PV)- and type 1 cannabinoid receptor (CB1R)-positive perisomatic interneurons innervate pyramidal cell bodies, and their role in synchronous population events spontaneously emerging in the human epileptic and non-epileptic neocortex, in vitro. Quantitative electron microscopy showed that the overall, PV+ and CB1R+ somatic inhibitory inputs remained unchanged in focal cortical epilepsy. On the contrary, the size of PV-stained synapses increased, and their number decreased in epileptic samples, in synchrony generating regions. Pharmacology demonstrated—in conjunction with the electron microscopy—that although both perisomatic cell types participate, PV+ cells have stronger influence on the generation of population activity in epileptic samples. The somatic inhibitory input of neocortical pyramidal cells remained almost intact in epilepsy, but the larger and consequently more efficient somatic synapses might account for a higher synchrony in this neuron population. This, together with epileptic hyperexcitability, might make a cortical region predisposed to generate or participate in hypersynchronous events.
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17
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Complement-associated loss of CA2 inhibitory synapses in the demyelinated hippocampus impairs memory. Acta Neuropathol 2021; 142:643-667. [PMID: 34170374 PMCID: PMC8423657 DOI: 10.1007/s00401-021-02338-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 06/03/2021] [Accepted: 06/14/2021] [Indexed: 12/27/2022]
Abstract
The complement system is implicated in synapse loss in the MS hippocampus, but the functional consequences of synapse loss remain poorly understood. Here, in post-mortem MS hippocampi with demyelination we find that deposits of the complement component C1q are enriched in the CA2 subfield, are linked to loss of inhibitory synapses and are significantly higher in MS patients with cognitive impairments compared to those with preserved cognitive functions. Using the cuprizone mouse model of demyelination, we corroborated that C1q deposits are highest within the demyelinated dorsal hippocampal CA2 pyramidal layer and co-localized with inhibitory synapses engulfed by microglia/macrophages. In agreement with the loss of inhibitory perisomatic synapses, we found that Schaffer collateral feedforward inhibition but not excitation was impaired in CA2 pyramidal neurons and accompanied by intrinsic changes and a reduced spike output. Finally, consistent with excitability deficits, we show that cuprizone-treated mice exhibit impaired encoding of social memories. Together, our findings identify CA2 as a critical circuit in demyelinated intrahippocampal lesions and memory dysfunctions in MS.
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18
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Freiman TM, Häussler U, Zentner J, Doostkam S, Beck J, Scheiwe C, Brandt A, Haas CA, Puhahn-Schmeiser B. Mossy fiber sprouting into the hippocampal region CA2 in patients with temporal lobe epilepsy. Hippocampus 2021; 31:580-592. [PMID: 33720466 DOI: 10.1002/hipo.23323] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 02/23/2021] [Accepted: 02/27/2021] [Indexed: 01/28/2023]
Abstract
Hippocampal sclerosis (HS) in Temporal Lobe Epilepsy (TLE) shows neuronal death in cornu ammonis (CA)1, CA3, and CA4. It is known that granule cells and CA2 neurons survive and their axons, the mossy fibers (MF), lose their target cells in CA3 and CA4 and sprout to the granule cell layer and molecular layer. We examined in TLE patients and in a mouse epilepsy model, whether MF sprouting is directed to the dentate gyrus or extends to distant CA regions and whether sprouting is associated with death of target neurons in CA3 and CA4. In 319 TLE patients, HS was evaluated by Wyler grade and International League against Epilepsy (ILAE) types using immunohistochemistry against neuronal nuclei (NeuN). Synaptoporin was used to colocalize MF. In addition, transgenic Thy1-eGFP mice were intrahippocampally injected with kainate and sprouting of eGFP-positive MFs was analyzed together with immunocytochemistry for regulator of G-protein signaling 14 (RGS14). In human HS Wyler III and IV as well as in ILAE 1, 2, and 3 specimens, we found synaptoporin-positive axon terminals in CA2 and even in CA1, associated with the extent of granule cell dispersion. Sprouting was seen in cases with cell death of target neurons in CA3 and CA4 (classical severe HS ILAE type 1) but also without this cell death (atypical HS ILAE type 2). Similarly, in epileptic mice eGFP-positive MFs sprouted to CA2 and beyond. The presence of MF terminals in the CA2 pyramidal cell layer and in CA1 was also correlated with the extent of granule cell dispersion. The similarity of our findings in human specimens and in the mouse model highlights the importance and opens up new chances of using translational approaches to determine mechanisms underlying TLE.
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Affiliation(s)
- Thomas M Freiman
- Department of Neurosurgery, Rostock University Medical Center, Rostock, Germany
| | - Ute Häussler
- Department of Neurosurgery, Experimental Epilepsy Research, Medical Center-University of Freiburg, Faculty of Medicine, Freiburg, Germany.,Faculty of Medicine, Center for Basics in NeuroModulation, University of Freiburg, Freiburg, Germany.,BrainLinks-BrainTools Center, University of Freiburg, Freiburg, Germany
| | - Josef Zentner
- Faculty of Medicine, Department of Neurosurgery, Medical Center-University of Freiburg, Freiburg, Germany
| | - Soroush Doostkam
- Faculty of Medicine, Institute of Neuropathology, Medical Center-University of Freiburg, Freiburg, Germany
| | - Jürgen Beck
- Faculty of Medicine, Department of Neurosurgery, Medical Center-University of Freiburg, Freiburg, Germany
| | - Christian Scheiwe
- Faculty of Medicine, Department of Neurosurgery, Medical Center-University of Freiburg, Freiburg, Germany
| | - Armin Brandt
- Epilepsy Center, University Medical Center, Albert-Ludwigs-University, Freiburg, Germany
| | - Carola A Haas
- Department of Neurosurgery, Experimental Epilepsy Research, Medical Center-University of Freiburg, Faculty of Medicine, Freiburg, Germany.,Faculty of Medicine, Center for Basics in NeuroModulation, University of Freiburg, Freiburg, Germany.,BrainLinks-BrainTools Center, University of Freiburg, Freiburg, Germany
| | - Barbara Puhahn-Schmeiser
- Faculty of Medicine, Department of Neurosurgery, Medical Center-University of Freiburg, Freiburg, Germany
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19
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Rasia-Filho AA, Guerra KTK, Vásquez CE, Dall’Oglio A, Reberger R, Jung CR, Calcagnotto ME. The Subcortical-Allocortical- Neocortical continuum for the Emergence and Morphological Heterogeneity of Pyramidal Neurons in the Human Brain. Front Synaptic Neurosci 2021; 13:616607. [PMID: 33776739 PMCID: PMC7991104 DOI: 10.3389/fnsyn.2021.616607] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 02/01/2021] [Indexed: 11/13/2022] Open
Abstract
Human cortical and subcortical areas integrate emotion, memory, and cognition when interpreting various environmental stimuli for the elaboration of complex, evolved social behaviors. Pyramidal neurons occur in developed phylogenetic areas advancing along with the allocortex to represent 70-85% of the neocortical gray matter. Here, we illustrate and discuss morphological features of heterogeneous spiny pyramidal neurons emerging from specific amygdaloid nuclei, in CA3 and CA1 hippocampal regions, and in neocortical layers II/III and V of the anterolateral temporal lobe in humans. Three-dimensional images of Golgi-impregnated neurons were obtained using an algorithm for the visualization of the cell body, dendritic length, branching pattern, and pleomorphic dendritic spines, which are specialized plastic postsynaptic units for most excitatory inputs. We demonstrate the emergence and development of human pyramidal neurons in the cortical and basomedial (but not the medial, MeA) nuclei of the amygdala with cells showing a triangular cell body shape, basal branched dendrites, and a short apical shaft with proximal ramifications as "pyramidal-like" neurons. Basomedial neurons also have a long and distally ramified apical dendrite not oriented to the pial surface. These neurons are at the beginning of the allocortex and the limbic lobe. "Pyramidal-like" to "classic" pyramidal neurons with laminar organization advance from the CA3 to the CA1 hippocampal regions. These cells have basal and apical dendrites with specific receptive synaptic domains and several spines. Neocortical pyramidal neurons in layers II/III and V display heterogeneous dendritic branching patterns adapted to the space available and the afferent inputs of each brain area. Dendritic spines vary in their distribution, density, shapes, and sizes (classified as stubby/wide, thin, mushroom-like, ramified, transitional forms, "atypical" or complex forms, such as thorny excrescences in the MeA and CA3 hippocampal region). Spines were found isolated or intermingled, with evident particularities (e.g., an extraordinary density in long, deep CA1 pyramidal neurons), and some showing a spinule. We describe spiny pyramidal neurons considerably improving the connectional and processing complexity of the brain circuits. On the other hand, these cells have some vulnerabilities, as found in neurodegenerative Alzheimer's disease and in temporal lobe epilepsy.
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Affiliation(s)
- Alberto A. Rasia-Filho
- Department of Basic Sciences/Physiology and Graduate Program in Biosciences, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brazil
- Graduate Program in Neuroscience, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Kétlyn T. Knak Guerra
- Graduate Program in Neuroscience, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Carlos Escobar Vásquez
- Graduate Program in Neuroscience, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Aline Dall’Oglio
- Department of Basic Sciences/Physiology and Graduate Program in Biosciences, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brazil
| | - Roman Reberger
- Medical Engineering Program, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Cláudio R. Jung
- Institute of Informatics, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Maria Elisa Calcagnotto
- Graduate Program in Neuroscience, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
- Neurophysiology and Neurochemistry of Neuronal Excitability and Synaptic Plasticity Laboratory, Department of Biochemistry and Biochemistry Graduate Program, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
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20
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Kandrács Á, Hofer KT, Tóth K, Tóth EZ, Entz L, Bagó AG, Erőss L, Jordán Z, Nagy G, Fabó D, Ulbert I, Wittner L. Presence of synchrony-generating hubs in the human epileptic neocortex. J Physiol 2019; 597:5639-5670. [PMID: 31523807 DOI: 10.1113/jp278499] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 09/06/2019] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS •Initiation of pathological synchronous events such as epileptic spikes and seizures is linked to the hyperexcitability of the neuronal network in both humans and animals. •In the present study, we show that epileptiform interictal-like spikes and seizures emerged in human neocortical slices by blocking GABAA receptors, following the disappearance of the spontaneously occurring synchronous population activity. •Large variability of temporally and spatially simple and complex spikes was generated by tissue from epileptic patients, whereas only simple events appeared in samples from non-epileptic patients. •Physiological population activity was associated with a moderate level of principal cell and interneuron firing, with a slight dominance of excitatory neuronal activity, whereas epileptiform events were mainly initiated by the synchronous and intense discharge of inhibitory cells. •These results help us to understand the role of excitatory and inhibitory neurons in synchrony-generating mechanisms, in both epileptic and non-epileptic conditions. ABSTRACT Understanding the role of different neuron types in synchrony generation is crucial for developing new therapies aiming to prevent hypersynchronous events such as epileptic seizures. Paroxysmal activity was linked to hyperexcitability and to bursting behaviour of pyramidal cells in animals. Human data suggested a leading role of either principal cells or interneurons, depending on the seizure morphology. In the present study, we aimed to uncover the role of excitatory and inhibitory processes in synchrony generation by analysing the activity of clustered single neurons during physiological and epileptiform synchronies in human neocortical slices. Spontaneous population activity was detected with a 24-channel laminar microelectrode in tissue derived from patients with or without preoperative clinical manifestations of epilepsy. This population activity disappeared by blocking GABAA receptors, and several variations of spatially and temporally simple or complex interictal-like spikes emerged in epileptic tissue, whereas peritumoural slices generated only simple spikes. Around one-half of the clustered neurons participated with an elevated firing rate in physiological synchronies with a slight dominance of excitatory cells. By contrast, more than 90% of the neurons contributed to interictal-like spikes and seizures, and an intense and synchronous discharge of inhibitory neurons was associated with the start of these events. Intrinsically bursting principal cells fired later than other neurons. Our data suggest that a balanced excitation and inhibition characterized physiological synchronies, whereas disinhibition-induced epileptiform events were initiated mainly by non-synaptically synchronized inhibitory neurons. Our results further highlight the differences between humans and animal models, and between in vivo and (pharmacologically manipulated) in vitro conditions.
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Affiliation(s)
- Ágnes Kandrács
- Institute of Cognitive Neuroscience and Psychology, Research Center for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary.,Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary
| | - Katharina T Hofer
- Institute of Cognitive Neuroscience and Psychology, Research Center for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary.,Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary
| | - Kinga Tóth
- Institute of Cognitive Neuroscience and Psychology, Research Center for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - Estilla Z Tóth
- Institute of Cognitive Neuroscience and Psychology, Research Center for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - László Entz
- National Institute of Clinical Neuroscience, Budapest, Hungary
| | - Attila G Bagó
- National Institute of Clinical Neuroscience, Budapest, Hungary
| | - Loránd Erőss
- National Institute of Clinical Neuroscience, Budapest, Hungary
| | - Zsófia Jordán
- National Institute of Clinical Neuroscience, Budapest, Hungary
| | - Gábor Nagy
- National Institute of Clinical Neuroscience, Budapest, Hungary
| | - Dániel Fabó
- National Institute of Clinical Neuroscience, Budapest, Hungary
| | - István Ulbert
- Institute of Cognitive Neuroscience and Psychology, Research Center for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary.,Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary.,National Institute of Clinical Neuroscience, Budapest, Hungary
| | - Lucia Wittner
- Institute of Cognitive Neuroscience and Psychology, Research Center for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary.,Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary.,National Institute of Clinical Neuroscience, Budapest, Hungary
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21
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Inhibition and oscillations in the human brain tissue in vitro. Neurobiol Dis 2019; 125:198-210. [DOI: 10.1016/j.nbd.2019.02.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 12/22/2018] [Accepted: 02/07/2019] [Indexed: 01/22/2023] Open
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22
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de Curtis M, Librizzi L, Uva L, Gnatkovsky V. GABAA receptor-mediated networks during focal seizure onset and progression in vitro. Neurobiol Dis 2019; 125:190-197. [DOI: 10.1016/j.nbd.2019.02.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 01/08/2019] [Accepted: 02/07/2019] [Indexed: 02/02/2023] Open
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Muñoz MD, Solís JM. Characterisation of the mechanisms underlying the special sensitivity of the CA2 hippocampal area to adenosine receptor antagonists. Neuropharmacology 2019; 144:9-18. [DOI: 10.1016/j.neuropharm.2018.10.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 09/17/2018] [Accepted: 10/12/2018] [Indexed: 12/28/2022]
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Abstract
PURPOSE It has been challenging to detect early changes preceding seizure onset in patients with epilepsy. This study investigated the preictal discharges (PIDs) by intracranial electroencephalogram of 11 seizures from 7 patients with mesial temporal lobe epilepsy. METHODS The EEG segments consisting of 30 seconds before ictal onset and 5 seconds after ictal onset were selected for analysis. After PID detection, the amplitude and interval were measured. According to the timing of PID onset, the 30-second period preceding seizure onset was divided into two stages: before PID stage and PID stage. The autocorrelation coefficients during the two stages were calculated and compared. RESULTS Preictal discharge amplitude progressively increased, while PID interval gradually decreased toward seizure onset. The autocorrelation coefficients of PID channels were significantly higher during PID stage than before PID stage. There was an overlap between channels with PIDs and seizure onset channels (80.77%). CONCLUSIONS Preictal discharges emerge prior to ictal event, with a dynamic change and a spatial correlation with seizure onset zone. These findings deepen our understanding of seizure generation and help early prediction and localization of seizure onset zone.
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25
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Reyes-Garcia SZ, Scorza CA, Araújo NS, Ortiz-Villatoro NN, Jardim AP, Centeno R, Yacubian EMT, Faber J, Cavalheiro EA. Different patterns of epileptiform-like activity are generated in the sclerotic hippocampus from patients with drug-resistant temporal lobe epilepsy. Sci Rep 2018; 8:7116. [PMID: 29740014 PMCID: PMC5940759 DOI: 10.1038/s41598-018-25378-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 04/19/2018] [Indexed: 12/26/2022] Open
Abstract
Human hippocampal slice preparations from patients with temporal lobe epilepsy (TLE) associated with hippocampal sclerosis (HS) are excellent material for the characterization of epileptiform-like activity. However, it is still unknown if hippocampal regions as cornu Ammonis (CA) 1, CA3 and CA4, generate population epileptiform-like activity. Here, we investigated epileptiform activities of the subiculum, CA1, CA2, CA3, CA4 (induced by elevation of extracellular potassium concentration) and the dentate gyrus (induced with hilar stimulation and elevation of potassium concentration) from sclerotic hippocampi of patients with drug-resistant TLE. Five types of epileptiform-like activity were observed: interictal-like events; periodic ictal spiking; seizure-like events; spreading depression-like events; tonic seizure-like events and no activity. Different susceptibilities to generate epileptiform activity among hippocampal regions were observed; the dentate gyrus was the most susceptible region followed by the subiculum, CA4, CA1, CA2 and CA3. The incidence of epileptiform activity pattern was associated with specific regions of the hippocampal formation. Moreover, it was observed that each region of the hippocampal formation exhibits frequency-specific ranges in each subfield of the sclerotic human tissue. In conclusion, this study demonstrates that epileptiform-like activity may be induced in different regions of the hippocampal formation, including regions that are severely affected by neuronal loss.
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Affiliation(s)
- Selvin Z Reyes-Garcia
- Departamento de Neurologia e Neurocirurgia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil. .,Departamento de Ciencias Morfológicas, Facultad de Ciencias Médicas, Universidad Nacional Autónoma de Honduras, Tegucigalpa, Honduras.
| | - Carla A Scorza
- Departamento de Neurologia e Neurocirurgia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Noemi S Araújo
- Departamento de Neurologia e Neurocirurgia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Nancy N Ortiz-Villatoro
- Departamento de Neurologia e Neurocirurgia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Anaclara Prada Jardim
- Departamento de Neurologia e Neurocirurgia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Ricardo Centeno
- Departamento de Neurologia e Neurocirurgia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Elza Márcia Targas Yacubian
- Departamento de Neurologia e Neurocirurgia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Jean Faber
- Departamento de Neurologia e Neurocirurgia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Esper A Cavalheiro
- Departamento de Neurologia e Neurocirurgia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
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26
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Abstract
Resected hippocampal tissue from patients with drug-resistant epilepsy presents a unique possibility to test novel treatment strategies directly in target tissue. The post-resection time for testing and analysis however is normally limited. Acute tissue slices allow for electrophysiological recordings typically up to 12 hours. To enable longer time to test novel treatment strategies such as, e.g., gene-therapy, we developed a method for keeping acute human brain slices viable over a longer period. Our protocol keeps neurons viable well up to 48 hours. Using a dual-flow chamber, which allows for microscopic visualisation of individual neurons with a submerged objective for whole-cell patch-clamp recordings, we report stable electrophysiological properties, such as action potential amplitude and threshold during this time. We also demonstrate that epileptiform activity, monitored by individual dentate granule whole-cell recordings, can be consistently induced in these slices, underlying the usefulness of this methodology for testing and/or validating novel treatment strategies for epilepsy.
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27
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Le Duigou C, Savary E, Morin-Brureau M, Gomez-Dominguez D, Sobczyk A, Chali F, Milior G, Kraus L, Meier JC, Kullmann DM, Mathon B, de la Prida LM, Dorfmuller G, Pallud J, Eugène E, Clemenceau S, Miles R. Imaging pathological activities of human brain tissue in organotypic culture. J Neurosci Methods 2018; 298:33-44. [PMID: 29427611 DOI: 10.1016/j.jneumeth.2018.02.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2017] [Revised: 01/27/2018] [Accepted: 02/02/2018] [Indexed: 12/17/2022]
Abstract
BACKGROUND Insights into human brain diseases may emerge from tissue obtained after operations on patients. However techniques requiring transduction of transgenes carried by viral vectors cannot be applied to acute human tissue. NEW METHOD We show that organotypic culture techniques can be used to maintain tissue from patients with three different neurological syndromes for several weeks in vitro. Optimized viral vector techniques and promoters for transgene expression are described. RESULTS Region-specific differences in neuronal form, firing pattern and organization as well as pathological activities were maintained over 40-50 days in culture. Both adeno-associated virus and lentivirus based vectors were persistently expressed from ∼10 days after application, providing 30-40 days to exploit genetically expressed constructs. Different promoters, including hSyn, e/hSyn, CMV and CaMKII, provided cell-type specific transgene expression. The Ca probe GCaMP let us explore epileptogenic synchrony and a FRET-based probe was used to follow activity of the kinase mTORC1. COMPARISON WITH EXISTING METHODS The use of a defined culture medium, with low concentrations of amino acids and no growth factors, permitted organotypic culture of tissue from humans aged 3-62 years. Epileptic activity was maintained and excitability changed relatively little until ∼6 weeks in culture. CONCLUSIONS Characteristic morphology and region-specific neuronal activities are maintained in organotypic culture of tissue from patients diagnosed with mesial temporal lobe epilepsy, cortical dysplasia and cortical glioblastoma. Viral vector techniques permit expression of probes for long-term measurements of multi-cellular activity and intra-cellular signaling.
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Affiliation(s)
- Caroline Le Duigou
- Cortex & Epilepsie, Inserm U1127, CNRS UMR7225, UPMC Univ Paris 6, Institut du Cerveau et de la Moelle épinière, Paris, 75013, France, France.
| | - Etienne Savary
- Cortex & Epilepsie, Inserm U1127, CNRS UMR7225, UPMC Univ Paris 6, Institut du Cerveau et de la Moelle épinière, Paris, 75013, France, France.
| | - Mélanie Morin-Brureau
- Cortex & Epilepsie, Inserm U1127, CNRS UMR7225, UPMC Univ Paris 6, Institut du Cerveau et de la Moelle épinière, Paris, 75013, France, France
| | - Daniel Gomez-Dominguez
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, E-28002, Spain
| | - André Sobczyk
- Cortex & Epilepsie, Inserm U1127, CNRS UMR7225, UPMC Univ Paris 6, Institut du Cerveau et de la Moelle épinière, Paris, 75013, France, France
| | - Farah Chali
- Cortex & Epilepsie, Inserm U1127, CNRS UMR7225, UPMC Univ Paris 6, Institut du Cerveau et de la Moelle épinière, Paris, 75013, France, France
| | - Giampaolo Milior
- Cortex & Epilepsie, Inserm U1127, CNRS UMR7225, UPMC Univ Paris 6, Institut du Cerveau et de la Moelle épinière, Paris, 75013, France, France
| | - Larissa Kraus
- Cell Physiology, Technische Universität Braunschweig, Braunschweig, Germany; Charite Universitätsmedizin, Clinical and Experimental Epileptology, Berlin, Germany; Berlin Institute of Health (BIH), 10178, Berlin, Germany
| | - Jochen C Meier
- Cell Physiology, Technische Universität Braunschweig, Braunschweig, Germany
| | | | - Bertrand Mathon
- Neurochirurgie, AP-HP, GH Pitie-Salpêtrière-Charles Foix, Paris, 75013, France
| | | | - Georg Dorfmuller
- Neurochirurgie, Fondation Ophtalmologique Rothschild, 75019, Paris, France
| | - Johan Pallud
- Neurochirurgie, Hôpital Sainte-Anne, Paris Descartes University, IMA-BRAIN, Inserm, U894 Centre de Psychiatrie et Neurosciences, Paris, 75014, France
| | - Emmanuel Eugène
- Inserm U839, UPMC Univ Paris 6, Institut du Fer-à-Moulin, Paris, 75005, France
| | - Stéphane Clemenceau
- Neurochirurgie, AP-HP, GH Pitie-Salpêtrière-Charles Foix, Paris, 75013, France
| | - Richard Miles
- Cortex & Epilepsie, Inserm U1127, CNRS UMR7225, UPMC Univ Paris 6, Institut du Cerveau et de la Moelle épinière, Paris, 75013, France, France.
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28
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Hippocampal area CA2: properties and contribution to hippocampal function. Cell Tissue Res 2018; 373:525-540. [PMID: 29335778 DOI: 10.1007/s00441-017-2769-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 12/07/2017] [Indexed: 12/30/2022]
Abstract
This review focuses on area CA2 of the hippocampus, as recent results have revealed the unique properties and surprising role of this region in encoding social, temporal and contextual aspects of memory. Originally identified and described by Lorente de No, in 1934, this region of the hippocampus has unique intra-and extra-hippocampal connectivity, sending and receiving input to septal and hypothalamic regions. Recent in vivo studies have indicated that CA2 pyramidal neurons encode spatial information during immobility and play an important role in the generation of sharp-wave ripples. Furthermore, CA2 neurons act to control overall excitability in the hippocampal network and have been found to be consistently altered in psychiatric diseases, indicating that normal function of this region is necessary for normal cognition. With its unique role, area CA2 has a unique molecular profile, interneuron density and composition. Furthermore, this region has an unusual manifestation of synaptic plasticity that does not occur post-synaptically at pyramidal neuron dendrities but through the local network of inhibitory neurons. While much progress has recently been made in understanding the large contribution of area CA2 to social memory formation, much still needs to be learned.
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29
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Tóth K, Hofer KT, Kandrács Á, Entz L, Bagó A, Erőss L, Jordán Z, Nagy G, Sólyom A, Fabó D, Ulbert I, Wittner L. Hyperexcitability of the network contributes to synchronization processes in the human epileptic neocortex. J Physiol 2017; 596:317-342. [PMID: 29178354 DOI: 10.1113/jp275413] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 11/15/2017] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Hyperexcitability and hypersynchrony of neuronal networks are thought to be linked to the generation of epileptic activity in both humans and animal models. Here we show that human epileptic postoperative neocortical tissue is able to generate two different types of synchronies in vitro. Epileptiform bursts occurred only in slices derived from epileptic patients and were hypersynchronous events characterized by high levels of excitability. Spontaneous population activity emerged in both epileptic and non-epileptic tissue, with a significantly lower degree of excitability and synchrony, and could not be linked to epilepsy. These results help us to understand better the role of excitatory and inhibitory neuronal circuits in the generation of population events, and to define the subtle border between physiological and pathological synchronies. ABSTRACT Interictal activity is a hallmark of epilepsy diagnostics and is linked to neuronal hypersynchrony. Little is known about perturbations in human epileptic neocortical microcircuits, and their role in generating pathological synchronies. To explore hyperexcitability of the human epileptic network, and its contribution to convulsive activity, we investigated an in vitro model of synchronous burst activity spontaneously occurring in postoperative tissue slices derived from patients with or without preoperative clinical and electrographic manifestations of epileptic activity. Human neocortical slices generated two types of synchronies. Interictal-like discharges (classified as epileptiform events) emerged only in epileptic samples, and were hypersynchronous bursts characterized by considerably elevated levels of excitation. Synchronous population activity was initiated in both epileptic and non-epileptic tissue, with a significantly lower degree of excitability and synchrony, and could not be linked to epilepsy. However, in pharmacoresistant epileptic tissue, a higher percentage of slices exhibited population activity, with higher local field potential gradient amplitudes. More intracellularly recorded neurons received depolarizing synaptic potentials, discharging more reliably during the events. Light and electron microscopic examinations showed slightly lower neuron densities and higher densities of excitatory synapses in the human epileptic neocortex. Our data suggest that human neocortical microcircuits retain their functionality and plasticity in vitro, and can generate two significantly different synchronies. We propose that population bursts might not be pathological events while interictal-like discharges may reflect the epileptogenicity of the human cortex. Our results show that hyperexcitability characterizes the human epileptic neocortical network, and that it is closely related to the emergence of synchronies.
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Affiliation(s)
- Kinga Tóth
- Institute of Cognitive Neuroscience and Psychology, Research Center for Natural Sciences, Hungarian Academy of Sciences, 1117, Budapest, Hungary.,Institute of Experimental Medicine, Hungarian Academy of Sciences, 1083, Budapest, Hungary
| | - Katharina T Hofer
- Institute of Cognitive Neuroscience and Psychology, Research Center for Natural Sciences, Hungarian Academy of Sciences, 1117, Budapest, Hungary.,Department of Information Technology, Pázmány Péter Catholic University, 1083, Budapest, Hungary
| | - Ágnes Kandrács
- Institute of Cognitive Neuroscience and Psychology, Research Center for Natural Sciences, Hungarian Academy of Sciences, 1117, Budapest, Hungary.,Department of Information Technology, Pázmány Péter Catholic University, 1083, Budapest, Hungary
| | - László Entz
- National Institute of Clinical Neuroscience, 1145, Budapest, Hungary
| | - Attila Bagó
- National Institute of Clinical Neuroscience, 1145, Budapest, Hungary
| | - Loránd Erőss
- National Institute of Clinical Neuroscience, 1145, Budapest, Hungary
| | - Zsófia Jordán
- National Institute of Clinical Neuroscience, 1145, Budapest, Hungary
| | - Gábor Nagy
- National Institute of Clinical Neuroscience, 1145, Budapest, Hungary
| | - András Sólyom
- National Institute of Clinical Neuroscience, 1145, Budapest, Hungary
| | - Dániel Fabó
- National Institute of Clinical Neuroscience, 1145, Budapest, Hungary
| | - István Ulbert
- Institute of Cognitive Neuroscience and Psychology, Research Center for Natural Sciences, Hungarian Academy of Sciences, 1117, Budapest, Hungary.,Department of Information Technology, Pázmány Péter Catholic University, 1083, Budapest, Hungary.,National Institute of Clinical Neuroscience, 1145, Budapest, Hungary
| | - Lucia Wittner
- Institute of Cognitive Neuroscience and Psychology, Research Center for Natural Sciences, Hungarian Academy of Sciences, 1117, Budapest, Hungary.,Institute of Experimental Medicine, Hungarian Academy of Sciences, 1083, Budapest, Hungary.,National Institute of Clinical Neuroscience, 1145, Budapest, Hungary
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30
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Jozwiak S, Becker A, Cepeda C, Engel J, Gnatkovsky V, Huberfeld G, Kaya M, Kobow K, Simonato M, Loeb JA. WONOEP appraisal: Development of epilepsy biomarkers-What we can learn from our patients? Epilepsia 2017; 58:951-961. [PMID: 28387933 PMCID: PMC5806696 DOI: 10.1111/epi.13728] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/20/2017] [Indexed: 12/13/2022]
Abstract
OBJECTIVE Current medications for patients with epilepsy work in only two of three patients. For those medications that do work, they only suppress seizures. They treat the symptoms, but do not modify the underlying disease, forcing patients to take these drugs with significant side effects, often for the rest of their lives. A major limitation in our ability to advance new therapeutics that permanently prevent, reduce the frequency of, or cure epilepsy comes from a lack of understanding of the disease coupled with a lack of reliable biomarkers that can predict who has or who will get epilepsy. METHODS The main goal of this report is to present a number of approaches for identifying reliable biomarkers from observing patients with brain disorders that have a high probability of producing epilepsy. RESULTS A given biomarker, or more likely a profile of biomarkers, will have both a quantity and a time course during epileptogenesis that can be used to predict who will get the disease, to confirm epilepsy as a diagnosis, to identify coexisting pathologies, and to monitor the course of treatments. SIGNIFICANCE Additional studies in patients and animal models could identify common and clinically valuable biomarkers to successfully translate animal studies into new and effective clinical trials.
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Affiliation(s)
- Sergiusz Jozwiak
- Department of Child Neurology, Medical University of Warsaw, Poland
- Department of Child Neurology, The Children’s Memorial Health Institute, Warsaw, Poland
| | - Albert Becker
- Section for Translational Epilepsy Research, Department of Neuropathology, University of Bonn Medical Center, Bonn, Germany
| | - Carlos Cepeda
- IDDRC, Semel Institute for Neuroscience & Human Behavior, University of California Los Angeles, Los Angeles, CA, USA
| | - Jerome Engel
- Departments of Neurology, Neurobiology, and Psychiatry & Biobehavioral Sciences and the Brain Research Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Vadym Gnatkovsky
- Unit of Epilepsy and Experimental Neurophysiology, Fondazione Istituto Neurologico Carlo Besta, Milan, Italy
| | - Gilles Huberfeld
- Sorbonne and UPMC University, AP-HP, Department of Neurophysiology, UPMC and La Pitié-Salpêtrière Hospital, Paris, France
- INSERM U1129, Paris Descartes University, PRES Sorbonne Paris, Cité, Paris, CEA, France
| | - Mehmet Kaya
- Department of Physiology, Koc University School of Medicine, Rumelifeneri Yolu, Sariver, Istanbul, Turkey
| | - Katja Kobow
- Department of Neuropathology, University Hospital Erlangen, Erlangen, Germany
| | - Michele Simonato
- Department of Medical Sciences, University of Ferrara and Division of Neuroscience, University Vita-Salute San Raffaele, Milan, Italy
| | - Jeffrey A. Loeb
- Department of Neurology and Rehabilitation, The University of Illinois at Chicago, Chicago, IL
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31
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Synaptic Reorganization of the Perisomatic Inhibitory Network in Hippocampi of Temporal Lobe Epileptic Patients. BIOMED RESEARCH INTERNATIONAL 2017; 2017:7154295. [PMID: 28116310 PMCID: PMC5237728 DOI: 10.1155/2017/7154295] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 11/07/2016] [Accepted: 11/14/2016] [Indexed: 11/18/2022]
Abstract
GABAergic inhibition and particularly perisomatic inhibition play a crucial role in controlling the firing properties of large principal cell populations. Furthermore, GABAergic network is a key element in the therapy attempting to reduce epileptic activity. Here, we present a review showing the synaptic changes of perisomatic inhibitory neuronal subtypes in the hippocampus of temporal lobe epileptic patients, including parvalbumin- (PV-) containing and cannabinoid Type 1 (CB1) receptor-expressing (and mainly cholecystokinin-positive) perisomatic inhibitory cells, known to control hippocampal synchronies. We have examined the synaptic input of principal cells in the dentate gyrus and Cornu Ammonis region in human control and epileptic hippocampi. Perisomatic inhibitory terminals establishing symmetric synapses were found to be sprouted in the dentate gyrus. Preservation of perisomatic input was found in the Cornu Ammonis 1 and Cornu Ammonis 2 regions, as long as pyramidal cells are present. Higher density of CB1-immunostained terminals was found in the epileptic hippocampus of sclerotic patients, especially in the dentate gyrus. We concluded that both types of (PV- and GABAergic CB1-containing) perisomatic inhibitory cells are mainly preserved or showed sprouting in epileptic samples. The enhanced perisomatic inhibitory signaling may increase principal cell synchronization and contribute to generation of epileptic seizures and interictal spikes.
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32
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Chevaleyre V, Piskorowski RA. Hippocampal Area CA2: An Overlooked but Promising Therapeutic Target. Trends Mol Med 2016; 22:645-655. [DOI: 10.1016/j.molmed.2016.06.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2016] [Revised: 06/10/2016] [Accepted: 06/10/2016] [Indexed: 10/21/2022]
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33
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Abstract
Hippocampal area CA2 has several features that distinguish it from CA1 and CA3, including a unique gene expression profile, failure to display long-term potentiation and relative resistance to cell death. A recent increase in interest in the CA2 region, combined with the development of new methods to define and manipulate its neurons, has led to some exciting new discoveries on the properties of CA2 neurons and their role in behaviour. Here, we review these findings and call attention to the idea that the definition of area CA2 ought to be revised in light of gene expression data.
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Age-Dependent Specific Changes in Area CA2 of the Hippocampus and Social Memory Deficit in a Mouse Model of the 22q11.2 Deletion Syndrome. Neuron 2016; 89:163-76. [PMID: 26748091 DOI: 10.1016/j.neuron.2015.11.036] [Citation(s) in RCA: 113] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Revised: 09/23/2015] [Accepted: 11/18/2015] [Indexed: 11/23/2022]
Abstract
Several neuropsychiatric disorders are associated with cognitive and social dysfunction. Postmortem studies of patients with schizophrenia have revealed specific changes in area CA2, a long-overlooked region of the hippocampus recently found to be critical for social memory formation. To examine how area CA2 is altered in psychiatric illness, we used the Df(16)A(+/-) mouse model of the 22q11.2 microdeletion, a genetic risk factor for developing several neuropsychiatric disorders, including schizophrenia. We report several age-dependent CA2 alterations: a decrease in the density of parvalbumin-expressing interneurons, a reduction in the amount of feedforward inhibition, and a change in CA2 pyramidal-neuron intrinsic properties. Furthermore, we found that area CA2 is less plastic in Df(16)A(+/-) mice, making it nearly impossible to evoke action potential firing in CA2 pyramidal neurons. Finally, we show that Df(16)A(+/-) mice display impaired social cognition, providing a potential mechanism and a neural substrate for this impairment in psychiatric disorders.
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35
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Häussler U, Rinas K, Kilias A, Egert U, Haas CA. Mossy fiber sprouting and pyramidal cell dispersion in the hippocampal CA2 region in a mouse model of temporal lobe epilepsy. Hippocampus 2015; 26:577-88. [PMID: 26482541 DOI: 10.1002/hipo.22543] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/09/2015] [Indexed: 11/06/2022]
Abstract
Dentate granule cells and the hippocampal CA2 region are resistant to cell loss associated with mesial temporal lobe epilepsy (MTLE). It is known that granule cells undergo mossy fiber sprouting in the dentate gyrus which contributes to a recurrent, proepileptogenic circuitry in the hippocampus. Here it is shown that mossy fiber sprouting also targets CA2 pyramidal cell somata and that the CA2 region undergoes prominent structural reorganization under epileptic conditions. Using the intrahippocampal kainate mouse model for MTLE and the CA2-specific markers Purkinje cell protein 4 (PCP4) and regulator of G-Protein signaling 14 (RGS14), it was found that during epileptogenesis CA2 neurons survive and disperse in direction of CA3 and CA1 resulting in a significantly elongated CA2 region. Using transgenic mice that express enhanced green fluorescent protein (eGFP) in granule cells and mossy fibers, we show that the recently described mossy fiber projection to CA2 undergoes sprouting resulting in aberrant large, synaptoporin-expressing mossy fiber boutons which surround the CA2 pyramidal cell somata. This opens up the potential for altered synaptic transmission that might contribute to epileptic activity in CA2. Indeed, intrahippocampal recordings in freely moving mice revealed that epileptic activity occurs concomitantly in the dentate gyrus and in CA2. Altogether, the results call attention to CA2 as a region affected by MTLE-associated pathological restructuring.
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Affiliation(s)
- Ute Häussler
- Experimental Epilepsy Research, Department of Neurosurgery, University Medical Center Freiburg, Freiburg, 79106, Germany
| | - Katrin Rinas
- Experimental Epilepsy Research, Department of Neurosurgery, University Medical Center Freiburg, Freiburg, 79106, Germany
| | - Antje Kilias
- Faculty of Biology, University of Freiburg, Freiburg, 79104, Germany.,Bernstein Center Freiburg, University of Freiburg, Freiburg, 79104, Germany.,Laboratory for Biomicrotechnology, Department of Microsystems Engineering - IMTEK, Faculty of Engineering, University of Freiburg, Freiburg, 79110, Germany
| | - Ulrich Egert
- Bernstein Center Freiburg, University of Freiburg, Freiburg, 79104, Germany.,Laboratory for Biomicrotechnology, Department of Microsystems Engineering - IMTEK, Faculty of Engineering, University of Freiburg, Freiburg, 79110, Germany.,BrainLinks-BrainTools, Cluster of Excellence, University of Freiburg, Freiburg, 79110, Germany
| | - Carola A Haas
- Experimental Epilepsy Research, Department of Neurosurgery, University Medical Center Freiburg, Freiburg, 79106, Germany.,Bernstein Center Freiburg, University of Freiburg, Freiburg, 79104, Germany.,BrainLinks-BrainTools, Cluster of Excellence, University of Freiburg, Freiburg, 79110, Germany
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Human brain slices for epilepsy research: Pitfalls, solutions and future challenges. J Neurosci Methods 2015; 260:221-32. [PMID: 26434706 DOI: 10.1016/j.jneumeth.2015.09.021] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 09/21/2015] [Accepted: 09/23/2015] [Indexed: 12/17/2022]
Abstract
Increasingly, neuroscientists are taking the opportunity to use live human tissue obtained from elective neurosurgical procedures for electrophysiological studies in vitro. Access to this valuable resource permits unique studies into the network dynamics that contribute to the generation of pathological electrical activity in the human epileptic brain. Whilst this approach has provided insights into the mechanistic features of electrophysiological patterns associated with human epilepsy, it is not without technical and methodological challenges. This review outlines the main difficulties associated with working with epileptic human brain slices from the point of collection, through the stages of preparation, storage and recording. Moreover, it outlines the limitations, in terms of the nature of epileptic activity that can be observed in such tissue, in particular, the rarity of spontaneous ictal discharges, we discuss manipulations that can be utilised to induce such activity. In addition to discussing conventional electrophysiological techniques that are routinely employed in epileptic human brain slices, we review how imaging and multielectrode array recordings could provide novel insights into the network dynamics of human epileptogenesis. Acute studies in human brain slices are ultimately limited by the lifetime of the tissue so overcoming this issue provides increased opportunity for information gain. We review the literature with respect to organotypic culture techniques that may hold the key to prolonging the viability of this material. A combination of long-term culture techniques, viral transduction approaches and electrophysiology in human brain slices promotes the possibility of large scale monitoring and manipulation of neuronal activity in epileptic microcircuits.
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Inhibitory Plasticity Permits the Recruitment of CA2 Pyramidal Neurons by CA3. eNeuro 2015; 2:eN-NWR-0049-15. [PMID: 26465002 PMCID: PMC4596021 DOI: 10.1523/eneuro.0049-15.2015] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 07/01/2015] [Accepted: 07/06/2015] [Indexed: 01/13/2023] Open
Abstract
Area CA2 is emerging as an important region for hippocampal memory formation. However, how CA2 pyramidal neurons (PNs) are engaged by intrahippocampal inputs remains unclear. Excitatory transmission between CA3 and CA2 is strongly inhibited and is not plastic. We show in mice that different patterns of activity can in fact increase the excitatory drive between CA3 and CA2. We provide evidence that this effect is mediated by a long-term depression at inhibitory synapses (iLTD), as it is evoked by the same protocols and shares the same pharmacology. In addition, we show that the net excitatory drive of distal inputs is also increased after iLTD induction. The disinhibitory increase in excitatory drive is sufficient to allow CA3 inputs to evoke action potential firing in CA2 PNs. Thus, these data reveal that the output of CA2 PNs can be gated by the unique activity-dependent plasticity of inhibitory neurons in area CA2.
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Synchronous inhibitory potentials precede seizure-like events in acute models of focal limbic seizures. J Neurosci 2015; 35:3048-55. [PMID: 25698742 DOI: 10.1523/jneurosci.3692-14.2015] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Interictal spikes in models of focal seizures and epilepsies are sustained by the synchronous activation of glutamatergic and GABAergic networks. The nature of population spikes associated with seizure initiation (pre-ictal spikes; PSs) is still undetermined. We analyzed the networks involved in the generation of both interictal and PSs in acute models of limbic cortex ictogenesis induced by pharmacological manipulations. Simultaneous extracellular and intracellular recordings from both principal cells and interneurons were performed in the medial entorhinal cortex of the in vitro isolated guinea pig brain during focal interictal and ictal discharges induced in the limbic network by intracortical and brief arterial infusions of either bicuculline methiodide (BMI) or 4-aminopyridine (4AP). Local application of BMI in the entorhinal cortex did not induce seizure-like events (SLEs), but did generate periodic interictal spikes sensitive to the glutamatergic non-NMDA receptor antagonist DNQX. Unlike local applications, arterial perfusion of either BMI or 4AP induced focal limbic SLEs. PSs just ahead of SLE were associated with hyperpolarizing potentials coupled with a complete blockade of firing in principal cells and burst discharges in putative interneurons. Interictal population spikes recorded from principal neurons between two SLEs correlated with a depolarizing potential. We demonstrate in two models of acute limbic SLE that PS events are different from interictal spikes and are sustained by synchronous activation of inhibitory networks. Our findings support a prominent role of synchronous network inhibition in the initiation of a focal seizure.
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Huberfeld G, Blauwblomme T, Miles R. Hippocampus and epilepsy: Findings from human tissues. Rev Neurol (Paris) 2015; 171:236-51. [PMID: 25724711 PMCID: PMC4409112 DOI: 10.1016/j.neurol.2015.01.563] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 01/20/2015] [Indexed: 11/18/2022]
Abstract
Surgical removal of the epileptogenic zone provides an effective therapy for several focal epileptic syndromes. This surgery offers the opportunity to study pathological activity in living human tissue for pharmacoresistant partial epilepsy syndromes including temporal lobe epilepsies with hippocampal sclerosis, cortical dysplasias, epilepsies associated with tumors and developmental malformations. Slices of tissue from patients with these syndromes retain functional neuronal networks and may generate epileptic activities. The properties of cells in this tissue may not be greatly changed, but excitatory synaptic transmission is often enhanced and GABAergic inhibition is preserved. Typically epileptic activity is not generated spontaneously by the neocortex, whether dysplastic or not, but can be induced by convulsants. The initiation of ictal discharges in the neocortex depends on both GABAergic signaling and increased extracellular potassium. In contrast, a spontaneous interictal-like activity is generated by tissues from patients with temporal lobe epilepsies associated with hippocampal sclerosis. This activity is initiated, not in the hippocampus but in the subiculum, an output region, which projects to the entorhinal cortex. Interictal events seem to be triggered by GABAergic cells, which paradoxically excite about 20% of subicular pyramidal cells while simultaneously inhibiting the majority. Interictal discharges thus depend on both GABAergic and glutamatergic signaling. The depolarizing effects of GABA depend on a pathological elevation in levels of chloride in some subicular cells, similar to those of developmentally immature cells. Such defect is caused by a perturbed expression of the cotransporters regulating intracellular chloride concentration, the importer NKCC1 and the extruder KCC2. Blockade of NKCC1 actions by the diuretic bumetanide restores intracellular chloride and thus hyperpolarizing GABAergic actions and consequently suppressing interictal activity.
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Affiliation(s)
- G Huberfeld
- Département de neurophysiologie, Sorbonne universités, UPMC - université Paris 06, UPMC, CHU de la Pitié-Salpêtrière, 47-83, boulevard de l'Hôpital, 75013 Paris, France; INSERM Unit U1129 Infantile Epilepsies and Brain Plasticity, University Paris Descartes, Sorbonne Paris Cité, CEA, 12, rue de l'École-de-Médecine, 75006 Paris, France.
| | - T Blauwblomme
- INSERM Unit U1129 Infantile Epilepsies and Brain Plasticity, University Paris Descartes, Sorbonne Paris Cité, CEA, 12, rue de l'École-de-Médecine, 75006 Paris, France; Neurosurgery Department, Necker-Enfants Malades Hospital, University Paris Descartes, PRES Sorbonne Paris Cité, 12, rue de l'École-de-Médecine, 75006 Paris, France
| | - R Miles
- Inserm U1127, CNRS UMR7225, Sorbonne universités, UPMC - université Paris 6 UMR S1127, Institut du cerveau et de la moelle épinière, 47, boulevard de l'Hôpital, 75013 Paris, France
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Dossi E, Blauwblomme T, Nabbout R, Huberfeld G, Rouach N. Multi-electrode array recordings of human epileptic postoperative cortical tissue. J Vis Exp 2014:e51870. [PMID: 25407747 PMCID: PMC4353385 DOI: 10.3791/51870] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Epilepsy, affecting about 1% of the population, comprises a group of neurological disorders characterized by the periodic occurrence of seizures, which disrupt normal brain function. Despite treatment with currently available antiepileptic drugs targeting neuronal functions, one third of patients with epilepsy are pharmacoresistant. In this condition, surgical resection of the brain area generating seizures remains the only alternative treatment. Studying human epileptic tissues has contributed to understand new epileptogenic mechanisms during the last 10 years. Indeed, these tissues generate spontaneous interictal epileptic discharges as well as pharmacologically-induced ictal events which can be recorded with classical electrophysiology techniques. Remarkably, multi-electrode arrays (MEAs), which are microfabricated devices embedding an array of spatially arranged microelectrodes, provide the unique opportunity to simultaneously stimulate and record field potentials, as well as action potentials of multiple neurons from different areas of the tissue. Thus MEAs recordings offer an excellent approach to study the spatio-temporal patterns of spontaneous interictal and evoked seizure-like events and the mechanisms underlying seizure onset and propagation. Here we describe how to prepare human cortical slices from surgically resected tissue and to record with MEAs interictal and ictal-like events ex vivo.
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Affiliation(s)
- Elena Dossi
- Neuroglial Interactions in Cerebral Physiopathology, Center for Interdisciplinary Research in Biology, CNRS UMR 7241, INSERM U1050, Collège de France
| | - Thomas Blauwblomme
- Infantile Epilepsies & Brain Plasticity, INSERM U1129, PRES, Paris Descartes University, Sorbonne Paris Cité, CEA; Neurosurgery Department, Necker Hospital, AP-HP, Paris Descartes University
| | - Rima Nabbout
- Infantile Epilepsies & Brain Plasticity, INSERM U1129, PRES, Paris Descartes University, Sorbonne Paris Cité, CEA; Rare Epilepsies Reference Center, Necker Hospital, AP-HP, Paris Descartes University
| | - Gilles Huberfeld
- Infantile Epilepsies & Brain Plasticity, INSERM U1129, PRES, Paris Descartes University, Sorbonne Paris Cité, CEA; Neurophysiology Department, La Pitié-Salpêtrière Hospital, AP-HP, Sorbonne and Pierre and Marie Curie University
| | - Nathalie Rouach
- Neuroglial Interactions in Cerebral Physiopathology, Center for Interdisciplinary Research in Biology, CNRS UMR 7241, INSERM U1050, Collège de France;
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41
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Eugène E, Cluzeaud F, Cifuentes-Diaz C, Fricker D, Le Duigou C, Clemenceau S, Baulac M, Poncer JC, Miles R. An organotypic brain slice preparation from adult patients with temporal lobe epilepsy. J Neurosci Methods 2014; 235:234-44. [PMID: 25064188 PMCID: PMC4426207 DOI: 10.1016/j.jneumeth.2014.07.009] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2014] [Revised: 07/13/2014] [Accepted: 07/15/2014] [Indexed: 02/05/2023]
Abstract
BACKGROUND A long-term in vitro preparation of diseased brain tissue would facilitate work on human pathologies. Organotypic tissue cultures retain an appropriate neuronal form, spatial arrangement, connectivity and electrical activity over several weeks. However, they are typically prepared with tissue from immature animals. In work using tissue from adult animals or humans, survival times longer than a few days have not been reported and it is not clear that pathological neuronal activities are retained. NEW METHOD We modified tissue preparation procedures and used a defined culture medium to make organotypic cultures of temporal lobe tissue obtained after operations on adult patients with pharmaco-resistant mesial temporal lobe epilepsies. RESULTS Organototypic culture preparation and maintenance techniques were judged on criteria of morphology and the generation of epileptiform activities. Short-duration (30-100 ms) interictal-like population activities were initiated spontaneously in either the subiculum, dentate gyrus or the CA2/CA3 region, but not the cortex, for up to 3-4 weeks in culture. Ictal-like discharges, of duration greater than 10s, were induced by convulsants. Epileptiform activities were modulated by both glutamatergic and GABAergic receptor antagonists. COMPARISON WITH EXISTING METHODS Our methods now permit the maintenance in organotypic culture of epileptic adult human tissue, generating appropriate epileptiform activity over 3-4 weeks. CONCLUSIONS We have shown that characteristic morphology and pathological activities are maintained in organotypic cultures of adult human tissue. These cultures should permit studies on the effects of prolonged drug treatments and long-term procedures such as viral transduction.
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Affiliation(s)
- Emmanuel Eugène
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris6 UMR S1127, Institut du Cerveau et de la Moelle épinière, 47 Boulevard de l'Hôpital, Paris 75013, France; INSERM, UMR-839, Paris 75005, France; UPMC Univ Paris, UMR-839, Paris 75005, France; Institut du Fer a Moulin, Paris 75005 France.
| | - Françoise Cluzeaud
- Service Microscopie, Centre de recherche biomedicale, CHU Bichat, Université Paris Diderot, 16 rue Henri Huchard, Paris 75870, France
| | - Carmen Cifuentes-Diaz
- INSERM, UMR-839, Paris 75005, France; UPMC Univ Paris, UMR-839, Paris 75005, France; Institut du Fer a Moulin, Paris 75005 France
| | - Desdemona Fricker
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris6 UMR S1127, Institut du Cerveau et de la Moelle épinière, 47 Boulevard de l'Hôpital, Paris 75013, France
| | - Caroline Le Duigou
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris6 UMR S1127, Institut du Cerveau et de la Moelle épinière, 47 Boulevard de l'Hôpital, Paris 75013, France
| | - Stephane Clemenceau
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris6 UMR S1127, Institut du Cerveau et de la Moelle épinière, 47 Boulevard de l'Hôpital, Paris 75013, France
| | - Michel Baulac
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris6 UMR S1127, Institut du Cerveau et de la Moelle épinière, 47 Boulevard de l'Hôpital, Paris 75013, France
| | - Jean-Christophe Poncer
- INSERM, UMR-839, Paris 75005, France; UPMC Univ Paris, UMR-839, Paris 75005, France; Institut du Fer a Moulin, Paris 75005 France
| | - Richard Miles
- Inserm U1127, CNRS UMR7225, Sorbonne Universités, UPMC Univ Paris6 UMR S1127, Institut du Cerveau et de la Moelle épinière, 47 Boulevard de l'Hôpital, Paris 75013, France.
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42
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Botcher NA, Falck JE, Thomson AM, Mercer A. Distribution of interneurons in the CA2 region of the rat hippocampus. Front Neuroanat 2014; 8:104. [PMID: 25309345 PMCID: PMC4176080 DOI: 10.3389/fnana.2014.00104] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 09/08/2014] [Indexed: 12/23/2022] Open
Abstract
The CA2 region of the mammalian hippocampus is a unique region with its own distinctive properties, inputs and pathologies. Disruption of inhibitory circuits in this region appears to be linked with the pathology of specific psychiatric disorders, promoting interest in its local circuitry, its role in hippocampal function and its dysfunction in disease. In previous studies, CA2 interneurons, including a novel subclass of CA2 dendrite-preferring interneurons that has not been identified in other CA regions, have been shown to display physiological, synaptic and morphological properties unique to this sub-field and may therefore play a crucial role in the hippocampal circuitry. The distributions of immuno-labeled interneurons in dorsal CA2 were studied and compared with those of interneurons in CA1 and CA3. Like those in CA1 and CA3, the somata of CA2 parvalbumin-immunoperoxidase-labeled interneurons were located primarily in Stratum Pyramidale (SP) and Stratum Oriens (SO), with very few cells in Stratum Radiatum (SR) and none in Stratum Lacunosum Moleculare (SLM). There was, however, a greater proportion of GAD-positive cells were immunopositive for PV in SP in CA2 than in CA1 or CA3. CA2 SP also contained a larger density of somatostatin-, calbindin-, and VIP-immunopositive somata than CA1 and/or CA3. Like those in CA1 and CA3, CCK-immunopositive somata in CA2 were mostly located in SR. Reelin- and NPY- immunolabeled cell bodies were located in all layers of the three CA regions. However, a higher density of Reelin-positive somata was found in SP and SR of CA2 than in CA1 or CA3.
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Affiliation(s)
- Nicola A Botcher
- Department of Pharmacology, University College London School of Pharmacy London, UK
| | - Joanne E Falck
- Department of Pharmacology, University College London School of Pharmacy London, UK
| | - Alex M Thomson
- Department of Pharmacology, University College London School of Pharmacy London, UK
| | - Audrey Mercer
- Department of Pharmacology, University College London School of Pharmacy London, UK
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43
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Hsiao MC, Yu PN, Song D, Liu CY, Heck CN, Millett D, Berger TW. An in vitro seizure model from human hippocampal slices using multi-electrode arrays. J Neurosci Methods 2014; 244:154-63. [PMID: 25244953 DOI: 10.1016/j.jneumeth.2014.09.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 09/08/2014] [Accepted: 09/11/2014] [Indexed: 11/28/2022]
Abstract
Temporal lobe epilepsy is a neurological condition marked by seizures, typically accompanied by large amplitude synchronous electrophysiological discharges, affecting a variety of mental and physical functions. The neurobiological mechanisms responsible for the onset and termination of seizures are still unclear. While pharmacological therapies can suppress the symptoms of seizures, typically 30% of patients do not respond well to drug control. Unilateral temporal lobectomy, a procedure in which a substantial part of the hippocampal formation and surrounding tissue is removed, is a common surgical treatment for medically refractory epilepsy. In this study, we have developed an in vitro model of epilepsy using human hippocampal slices resected from patients suffering from intractable mesial temporal lobe epilepsy. We show that using a planar multi-electrode array system, spatio-temporal inter-ictal like activity can be consistently recorded in high-potassium (8 mM), low-magnesium (0.25 mM) artificial cerebral spinal fluid with 4-aminopyridine (100 μM) added. The induced epileptiform discharges can be recorded in different subregions of the hippocampus, including dentate, CA1 and subiculum. This new paradigm will allow the study of seizure generation in different subregions of hippocampus simultaneously, as well as propagation of seizure activity throughout the intrinsic circuitry of hippocampus. This experimental model also should provide insights into seizure control and prevention, while providing a platform to develop novel, anti-seizure therapeutics.
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Affiliation(s)
- Min-Chi Hsiao
- Department of Biomedical Engineering, Center for Neural Engineering, University of Southern California, Los Angeles, CA 90089, USA.
| | - Pen-Ning Yu
- Department of Biomedical Engineering, Center for Neural Engineering, University of Southern California, Los Angeles, CA 90089, USA.
| | - Dong Song
- Department of Biomedical Engineering, Center for Neural Engineering, University of Southern California, Los Angeles, CA 90089, USA.
| | - Charles Y Liu
- Department of Neurological Surgery and Neurology, USC Keck School of Medicine, USC Center for Neurorestoration, Department of Biomedical Engineering, and Rancho Los Amigos National Rehabilitation Center, USA.
| | - Christianne N Heck
- Department of Neurology, USC Keck School of Medicine, USC Center for Neurorestoration, Los Angeles, CA 90033, USA.
| | - David Millett
- Department of Neurology, USC Keck School of Medicine, USC Center for Neurorestoration, Los Angeles, CA 90033, USA; Rancho Los Amigos National Rehabilitation Center, Downey, CA 90242, USA.
| | - Theodore W Berger
- Department of Biomedical Engineering, Center for Neural Engineering, University of Southern California, Los Angeles, CA 90089, USA.
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Kerekes BP, Tóth K, Kaszás A, Chiovini B, Szadai Z, Szalay G, Pálfi D, Bagó A, Spitzer K, Rózsa B, Ulbert I, Wittner L. Combined two-photon imaging, electrophysiological, and anatomical investigation of the human neocortex in vitro. NEUROPHOTONICS 2014; 1:011013. [PMID: 26157969 PMCID: PMC4478968 DOI: 10.1117/1.nph.1.1.011013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 08/19/2014] [Accepted: 08/20/2014] [Indexed: 05/06/2023]
Abstract
Spontaneous synchronous population activity (SPA) can be detected by electrophysiological methods in cortical slices of epileptic patients, maintained in a physiological medium in vitro. In order to gain additional spatial information about the network mechanisms involved in the SPA generation, we combined electrophysiological studies with two-photon imaging. Neocortical slices prepared from postoperative tissue of epileptic and tumor patients were maintained in a dual perfusion chamber in a physiological incubation medium. SPA was recorded with a 24-channel extracellular linear microelectrode covering all neocortical layers. After identifying the electrophysiologically active regions of the slice, bolus loading of neuronal and glial markers was applied on the tissue. SPA-related [Formula: see text] transients were detected in a large population of neighboring neurons with two-photon microscopy, simultaneous with extracellular SPA and intracellular whole-cell patch-clamp recordings. The intracellularly recorded cells were filled for subsequent anatomy. The cells were reconstructed in three dimensions and examined with light- and transmission electron microscopy. Combining high spatial resolution two-photon [Formula: see text] imaging techniques and high temporal resolution extra- and intracellular electrophysiology with cellular anatomy may permit a deeper understanding of the structural and functional properties of the human neocortex.
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Affiliation(s)
- Bálint Péter Kerekes
- Pázmány Péter Catholic University, Faculty of Information Technology and Bionics, H-1083 Budapest, Práter utca 50/a, Hungary
- Research Centre for Natural Sciences, Hungarian Academy of Sciences, Institute of Cognitive Neuroscience and Psychology, Budapest, Hungary
| | - Kinga Tóth
- Research Centre for Natural Sciences, Hungarian Academy of Sciences, Institute of Cognitive Neuroscience and Psychology, Budapest, Hungary
| | - Attila Kaszás
- Pázmány Péter Catholic University, Faculty of Information Technology and Bionics, H-1083 Budapest, Práter utca 50/a, Hungary
- Two-Photon Imaging Center, Hungarian Academy of Sciences, Institute of Experimental Medicine, Budapest, Hungary
| | - Balázs Chiovini
- Pázmány Péter Catholic University, Faculty of Information Technology and Bionics, H-1083 Budapest, Práter utca 50/a, Hungary
- Two-Photon Imaging Center, Hungarian Academy of Sciences, Institute of Experimental Medicine, Budapest, Hungary
| | - Zoltán Szadai
- Pázmány Péter Catholic University, Faculty of Information Technology and Bionics, H-1083 Budapest, Práter utca 50/a, Hungary
- Two-Photon Imaging Center, Hungarian Academy of Sciences, Institute of Experimental Medicine, Budapest, Hungary
| | - Gergely Szalay
- Two-Photon Imaging Center, Hungarian Academy of Sciences, Institute of Experimental Medicine, Budapest, Hungary
| | - Dénes Pálfi
- Pázmány Péter Catholic University, Faculty of Information Technology and Bionics, H-1083 Budapest, Práter utca 50/a, Hungary
- Two-Photon Imaging Center, Hungarian Academy of Sciences, Institute of Experimental Medicine, Budapest, Hungary
| | - Attila Bagó
- National Institute of Clinical Neuroscience, Department of Neurooncology, Budapest, Hungary
| | - Klaudia Spitzer
- Two-Photon Imaging Center, Hungarian Academy of Sciences, Institute of Experimental Medicine, Budapest, Hungary
| | - Balázs Rózsa
- Pázmány Péter Catholic University, Faculty of Information Technology and Bionics, H-1083 Budapest, Práter utca 50/a, Hungary
- Two-Photon Imaging Center, Hungarian Academy of Sciences, Institute of Experimental Medicine, Budapest, Hungary
| | - István Ulbert
- Pázmány Péter Catholic University, Faculty of Information Technology and Bionics, H-1083 Budapest, Práter utca 50/a, Hungary
- Research Centre for Natural Sciences, Hungarian Academy of Sciences, Institute of Cognitive Neuroscience and Psychology, Budapest, Hungary
- Address all correspondence to: István Ulbert, E-mail:
| | - Lucia Wittner
- Research Centre for Natural Sciences, Hungarian Academy of Sciences, Institute of Cognitive Neuroscience and Psychology, Budapest, Hungary
- National Institute of Clinical Neuroscience, Department of Neurooncology, Budapest, Hungary
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45
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Karlócai MR, Kohus Z, Káli S, Ulbert I, Szabó G, Máté Z, Freund TF, Gulyás AI. Physiological sharp wave-ripples and interictal events in vitro: what's the difference? ACTA ACUST UNITED AC 2014; 137:463-85. [PMID: 24390441 DOI: 10.1093/brain/awt348] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Sharp wave-ripples and interictal events are physiological and pathological forms of transient high activity in the hippocampus with similar features. Sharp wave-ripples have been shown to be essential in memory consolidation, whereas epileptiform (interictal) events are thought to be damaging. It is essential to grasp the difference between physiological sharp wave-ripples and pathological interictal events to understand the failure of control mechanisms in the latter case. We investigated the dynamics of activity generated intrinsically in the Cornu Ammonis region 3 of the mouse hippocampus in vitro, using four different types of intervention to induce epileptiform activity. As a result, sharp wave-ripples spontaneously occurring in Cornu Ammonis region 3 disappeared, and following an asynchronous transitory phase, activity reorganized into a new form of pathological synchrony. During epileptiform events, all neurons increased their firing rate compared to sharp wave-ripples. Different cell types showed complementary firing: parvalbumin-positive basket cells and some axo-axonic cells stopped firing as a result of a depolarization block at the climax of the events in high potassium, 4-aminopyridine and zero magnesium models, but not in the gabazine model. In contrast, pyramidal cells began firing maximally at this stage. To understand the underlying mechanism we measured changes of intrinsic neuronal and transmission parameters in the high potassium model. We found that the cellular excitability increased and excitatory transmission was enhanced, whereas inhibitory transmission was compromised. We observed a strong short-term depression in parvalbumin-positive basket cell to pyramidal cell transmission. Thus, the collapse of pyramidal cell perisomatic inhibition appears to be a crucial factor in the emergence of epileptiform events.
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Affiliation(s)
- Mária R Karlócai
- 1 Laboratory of Cerebral Cortex, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
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Delta-opioid receptors mediate unique plasticity onto parvalbumin-expressing interneurons in area CA2 of the hippocampus. J Neurosci 2013; 33:14567-78. [PMID: 24005307 DOI: 10.1523/jneurosci.0649-13.2013] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Inhibition is critical for controlling information transfer in the brain. However, the understanding of the plasticity and particular function of different interneuron subtypes is just emerging. Using acute hippocampal slices prepared from adult mice, we report that in area CA2 of the hippocampus, a powerful inhibitory transmission is acting as a gate to prevent CA3 inputs from driving CA2 neurons. Furthermore, this inhibition is highly plastic, and undergoes a long-term depression following high-frequency 10 Hz or theta-burst induction protocols. We describe a novel form of long-term depression at parvalbumin-expressing (PV+) interneuron synapses that is dependent on delta-opioid receptor (DOR) activation. Additionally, PV+ interneuron transmission is persistently depressed by DOR activation in area CA2 but only transiently depressed in area CA1. These results provide evidence for a differential temporal modulation of PV+ synapses between two adjacent cortical circuits, and highlight a new function of PV+ cells in controlling information transfer.
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47
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Alvarado-Rojas C, Lehongre K, Bagdasaryan J, Bragin A, Staba R, Engel J, Navarro V, Le Van Quyen M. Single-unit activities during epileptic discharges in the human hippocampal formation. Front Comput Neurosci 2013; 7:140. [PMID: 24151464 PMCID: PMC3799238 DOI: 10.3389/fncom.2013.00140] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 09/27/2013] [Indexed: 11/13/2022] Open
Abstract
Between seizures the brain of patients with epilepsy generates pathological patterns of synchronous activity, designated as interictal epileptiform discharges (ID). Using microelectrodes in the hippocampal formations of 8 patients with drug-resistant temporal lobe epilepsy, we studied ID by simultaneously analyzing action potentials from individual neurons and the local field potentials (LFPs) generated by the surrounding neuronal network. We found that ~30% of the units increased their firing rate during ID and 40% showed a decrease during the post-ID period. Surprisingly, 30% of units showed either an increase or decrease in firing rates several hundred of milliseconds before the ID. In 4 patients, this pre-ID neuronal firing was correlated with field high-frequency oscillations at 40-120 Hz. Finally, we observed that only a very small subset of cells showed significant coincident firing before or during ID. Taken together, we suggested that, in contrast to traditional views, ID are generated by a sparse neuronal network and followed a heterogeneous synchronization process initiated over several hundreds of milliseconds before the paroxysmal discharges.
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Affiliation(s)
- Catalina Alvarado-Rojas
- Centre de Recherche de l'Institut du Cerveau et de la Moelle Epinière, INSERM UMRS 975 - CNRS UMR 7225, Hôpital de la Pitié-SalpêtrièreParis, France
- Université Pierre et Marie CurieParis, France
| | - Katia Lehongre
- Centre de Recherche de l'Institut du Cerveau et de la Moelle Epinière, INSERM UMRS 975 - CNRS UMR 7225, Hôpital de la Pitié-SalpêtrièreParis, France
- Université Pierre et Marie CurieParis, France
| | - Juliana Bagdasaryan
- Centre de Recherche de l'Institut du Cerveau et de la Moelle Epinière, INSERM UMRS 975 - CNRS UMR 7225, Hôpital de la Pitié-SalpêtrièreParis, France
- Université Pierre et Marie CurieParis, France
| | - Anatol Bragin
- Department of Neurology, David Geffen School of Medicine at UCLALos Angeles, CA, USA
| | - Richard Staba
- Department of Neurology, David Geffen School of Medicine at UCLALos Angeles, CA, USA
| | - Jerome Engel
- Department of Neurology, David Geffen School of Medicine at UCLALos Angeles, CA, USA
| | - Vincent Navarro
- Centre de Recherche de l'Institut du Cerveau et de la Moelle Epinière, INSERM UMRS 975 - CNRS UMR 7225, Hôpital de la Pitié-SalpêtrièreParis, France
- Université Pierre et Marie CurieParis, France
- Epilepsy Unit, Groupe Hospitalier Pitié-SalpêtrièreParis, France
| | - Michel Le Van Quyen
- Centre de Recherche de l'Institut du Cerveau et de la Moelle Epinière, INSERM UMRS 975 - CNRS UMR 7225, Hôpital de la Pitié-SalpêtrièreParis, France
- Université Pierre et Marie CurieParis, France
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Kandratavicius L, Rosa-Neto P, Monteiro MR, Guiot MC, Assirati JA, Carlotti CG, Kobayashi E, Leite JP. Distinct increased metabotropic glutamate receptor type 5 (mGluR5) in temporal lobe epilepsy with and without hippocampal sclerosis. Hippocampus 2013; 23:1212-30. [PMID: 23804486 PMCID: PMC4165311 DOI: 10.1002/hipo.22160] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/31/2013] [Indexed: 12/04/2022]
Abstract
Metabotropic glutamate receptor type 5 (mGluR5) upregulation in temporal lobe epilepsy (TLE) and the correlation of its expression with features of hippocampal sclerosis (HS) remains unclear. Here we characterized mGluR5 immunoreactivity in hippocampus, entorhinal cortex (EC), and subiculum of TLE specimens with confirmed HS, with neocortical TLE (non-HS) and necropsy controls. We correlated mGluR5 immunoreactivity with neuronal density, mossy fiber sprouting, astrogliosis (GFAP), and dendritic alterations (MAP2). TLE specimens showed increased mGluR5 expression, which was most pronounced in the EC, subiculum, CA2, and dentate gyrus outer molecular layer. Increased mGluR5 expression was seen in hippocampal head and body segments and was independent of neuronal density, astrogliosis, or dendritic alterations. Positive correlation between mGluR5 expression with mossy fiber sprouting and with MAP2 in CA3 and CA1 was found only in HS specimens. Negative correlation between mGluR5 expression with seizure frequency and epilepsy duration was found only in non-HS cases. Specimens from HS patients without previous history of febrile seizure (FS) showed higher mGluR5 and MAP2 expression in CA2. Our study suggests that mGluR5 upregulation is part of a repertoire of post-synaptic adaptations that might control overexcitation and excessive glutamate release rather than a dysfunction that leads to seizure facilitation. That would explain why non-HS cases, on which seizures are likely to originate outside the hippocampal formation, also exhibit upregulated mGluR5. On the other hand, lower mGluR5 expression was related to increased seizure frequency. In addition to its role in hyperexcitability, mGluR5 upregulation could play a role in counterbalance mechanisms along the hyperexcitable circuitry uniquely altered in sclerotic hippocampal formation. Inefficient post-synaptic compensatory morphological (dendritic branching) and glutamatergic (mGluR5 expression) mechanisms in CA2 subfield could potentially underlie the association of FS with HS and TLE. © 2013 Wiley Periodicals, Inc.
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Affiliation(s)
- Ludmyla Kandratavicius
- Department of Neurosciences and Behavior, Ribeirao Preto Medical School, University of Sao PauloBrazil
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill UniversityMontreal, Canada
| | - Pedro Rosa-Neto
- Translational Neuroimaging Laboratory, Department of Neurology and Neurosurgery, Douglas Research Institute, McGill UniversityMontreal, Canada
| | - Mariana Raquel Monteiro
- Department of Neurosciences and Behavior, Ribeirao Preto Medical School, University of Sao PauloBrazil
| | - Marie-Christine Guiot
- Department of Pathology, Montreal Neurological Institute, McGill UniversityMontreal, Canada
| | | | | | - Eliane Kobayashi
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill UniversityMontreal, Canada
| | - Joao Pereira Leite
- Department of Neurosciences and Behavior, Ribeirao Preto Medical School, University of Sao PauloBrazil
- *Correspondence to: Joao Pereira Leite, Ribeirao Preto Medical School, Department of Neurosciences and Behavior, University of Sao Paulo, Av Bandeirantes 3900, 14049-900, Ribeirao Preto, SP, Brazil. E-mail:
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49
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Alarcón G, Martinez J, Kerai SV, Lacruz ME, Quiroga RQ, Selway RP, Richardson MP, García Seoane JJ, Valentín A. In vivo neuronal firing patterns during human epileptiform discharges replicated by electrical stimulation. Clin Neurophysiol 2012; 123:1736-44. [PMID: 22410162 PMCID: PMC3432232 DOI: 10.1016/j.clinph.2012.02.062] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Revised: 02/06/2012] [Accepted: 02/06/2012] [Indexed: 11/10/2022]
Abstract
OBJECTIVE To describe neuronal firing patterns observed during human spontaneous interictal epileptiform discharges (IEDs) and responses to single pulse electrical stimulation (SPES). METHODS Activity of single neurons was recorded during IEDs and after SPES in 11 consecutive patients assessed with depth EEG electrodes and attached microelectrodes. RESULTS A total of 66 neurons were recorded during IEDs and 151 during SPES. We have found essentially similar patterns of neuronal firing during IEDs and after SPES, namely: (a) a burst of high frequency firing lasting less than 100 ms (in 39% and 25% of local neurons, respectively for IED and SPES); (b) a period of suppression in firing lasting around 100-1300 ms (in 19% and 14%, respectively); (c) a burst followed by suppression (in 10% and 12%, respectively); (d) no-change (in 32% and 50%, respectively). CONCLUSIONS The similarities in neuronal firing patterns associated with IEDs and SPES suggest that, although both phenomena are initiated differently, they result in the activation of a common cortical mechanism, probably initiated by brief synchronised burst firing in some cells followed by long inhibition. SIGNIFICANCE The findings provide direct in vivo human evidence to further comprehend the pathophysiology of human focal epilepsy.
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Affiliation(s)
- Gonzalo Alarcón
- Department of Clinical Neuroscience, Institute of Psychiatry, King's College London, United Kingdom.
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Mercer A, Botcher NA, Eastlake K, Thomson AM. SP-SR interneurones: a novel class of neurones of the CA2 region of the hippocampus. Hippocampus 2012; 22:1758-69. [PMID: 22431345 DOI: 10.1002/hipo.22010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/30/2012] [Indexed: 11/10/2022]
Abstract
The CA2 region of the hippocampus has distinctive properties and inputs and may be linked with the pathology of specific psychiatric and neurological disorders. It is, therefore, important to understand CA2 circuitry and its involvement in the circuitry of the hippocampus. Properties of CA2 basket cells have been reported. However, other classes of CA2 interneurones with cell bodies located in stratum pyramidale remained to be described. In this study, the unusual axonal arbors of a novel subclass of dendrite-preferring CA2 interneurones whose somata are located in the pyramidal cell layer was revealed following intracellular recordings and biocytin labeling. One to four apical dendrites emerged from the soma, branched in stratum radiatum (SR) forming a tuft, but rarely penetrated stratum lacunosum-moleculare (SLM). One or two basal dendrites branched close to the soma, the branches extended through stratum oriens (SO) and often reached the alveus. Unlike CA2 bistratified cells, the axons of these cells arborized almost exclusively in SR with few, if any, branches extending to stratum pyramidale (SP), SO, or SLM. These interneurones again, unlike bistratified cells, were immunonegative for parvalbumin and cholecystokinin. Electrophysiologically, they were similar to some CA2 basket and bistratified cells in that they presented a "sag" in response to hyperpolarizing current injections and displayed spike frequency adaptation. They targeted the apical dendrites of neighboring CA2 pyramidal cells and received inputs from them.
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Affiliation(s)
- Audrey Mercer
- Department of Pharmacology, UCL School of Pharmacy, London, United Kingdom.
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