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Cai Z, Jiang X, Bagić A, Worrell GA, Richardson M, He B. Spontaneous HFO Sequences Reveal Propagation Pathways for Precise Delineation of Epileptogenic Networks. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.02.592202. [PMID: 38746136 PMCID: PMC11092614 DOI: 10.1101/2024.05.02.592202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Epilepsy, a neurological disorder affecting millions worldwide, poses great challenges in precisely delineating the epileptogenic zone - the brain region generating seizures - for effective treatment. High-frequency oscillations (HFOs) are emerging as promising biomarkers; however, the clinical utility is hindered by the difficulties in distinguishing pathological HFOs from non- epileptiform activities at single electrode and single patient resolution and understanding their dynamic role in epileptic networks. Here, we introduce an HFO-sequencing approach to analyze spontaneous HFOs traversing cortical regions in 40 drug-resistant epilepsy patients. This data- driven method automatically detected over 8.9 million HFOs, pinpointing pathological HFO- networks, and unveiled intricate millisecond-scale spatiotemporal dynamics, stability, and functional connectivity of HFOs in prolonged intracranial EEG recordings. These HFO sequences demonstrated a significant improvement in localization of epileptic tissue, with an 818.47% increase in concordance with seizure-onset zone (mean error: 2.92 mm), compared to conventional benchmarks. They also accurately predicted seizure outcomes for 90% AUC based on pre-surgical information using generalized linear models. Importantly, this mapping remained reliable even with short recordings (mean standard deviation: 3.23 mm for 30-minute segments). Furthermore, HFO sequences exhibited distinct yet highly repetitive spatiotemporal patterns, characterized by pronounced synchrony and predominant inward information flow from periphery towards areas involved in propagation, suggesting a crucial role for excitation-inhibition balance in HFO initiation and progression. Together, these findings shed light on the intricate organization of epileptic network and highlight the potential of HFO-sequencing as a translational tool for improved diagnosis, surgical targeting, and ultimately, better outcomes for vulnerable patients with drug-resistant epilepsy. One Sentence Summary Pathological fast brain oscillations travel like traffic along varied routes, outlining recurrently visited neural sites emerging as critical hotspots in epilepsy network.
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Wenzel M, Huberfeld G, Grayden DB, de Curtis M, Trevelyan AJ. A debate on the neuronal origin of focal seizures. Epilepsia 2023; 64 Suppl 3:S37-S48. [PMID: 37183507 DOI: 10.1111/epi.17650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 04/26/2023] [Accepted: 05/12/2023] [Indexed: 05/16/2023]
Abstract
A critical question regarding how focal seizures start is whether we can identify particular cell classes that drive the pathological process. This was the topic for debate at the recent International Conference for Technology and Analysis of Seizures (ICTALS) meeting (July 2022, Bern, CH) that we summarize here. The debate has been fueled in recent times by the introduction of powerful new ways to manipulate subpopulations of cells in relative isolation, mostly using optogenetics. The motivation for resolving the debate is to identify novel targets for therapeutic interventions through a deeper understanding of the etiology of seizures.
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Affiliation(s)
- Michael Wenzel
- Department of Epileptology, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Gilles Huberfeld
- Neurology Department, Hopital Fondation Adolphe de Rothschild, Paris, France
- Center for Interdisciplinary Research in Biology (CIRB), College de France, CNRS, INSERM, Université PSL, Paris, France
| | - David B Grayden
- Department of Biomedical Engineering, The University of Melbourne, Melbourne, Victoria, Australia
- Department of Medicine, St Vincent's Hospital, The University of Melbourne, Melbourne, Victoria, Australia
- Graeme Clark Institute, The University of Melbourne, Melbourne, Victoria, Australia
| | - Marco de Curtis
- Epilepsy Unit, Fondazione I.R.C.C.S., Istituto Neurologico Carlo Besta, Milan, Italy
| | - Andrew J Trevelyan
- Newcastle University Biosciences Institute, Medical School, Framlington Place, Newcastle upon Tyne, UK
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3
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Guo F, Cui Y, Li A, Liu M, Jian Z, Chen K, Yao D, Guo D, Xia Y. Differential patterns of very high-frequency oscillations in two seizure types of the pilocarpine-induced TLE model. Brain Res Bull 2023; 204:110805. [PMID: 37925081 DOI: 10.1016/j.brainresbull.2023.110805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Revised: 10/08/2023] [Accepted: 10/30/2023] [Indexed: 11/06/2023]
Abstract
AIMS Very high-frequency oscillations (VHFOs, >500 Hz) are considered a highly sensitive biomarker of seizures. We hypothesized that VHFOs may exhibit specificity towards hypersynchronous (HYP) seizures and low-voltage fast (LVF) seizures in temporal lobe epilepsy (TLE). METHODS Local field potentials were recorded from the hippocampal network in TLE mice induced by pilocarpine. Subsequently, we analyzed the VHFO features, including their temporal-frequency characteristics and VHFO/theta coupling, during three states: baseline, preictal, and postictal for both HYP- and LVF-seizure groups. RESULTS Significant changes in most of the VHFO features were observed during the preictal state in both seizure groups. In the postictal state, VHFO features in the HYP-seizure group exhibited inverse alterations and appeared to align with those observed during baseline conditions. However, such phenomena were not observed after TLE seizures in the LVF-seizure group. CONCLUSION Our findings highlight distinct patterns of VHFO feature changes across different states of HYP seizures and LVF seizures. These results suggest that VHFOs could serve as indicative biomarkers for seizure alterations specifically associated with HYP-seizure states.
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Affiliation(s)
- Fengru Guo
- Department of Neurosurgery, Sichuan Provincial People's Hospital, MOE Key Lab for Neuroinformation, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Yan Cui
- Department of Neurosurgery, Sichuan Provincial People's Hospital, MOE Key Lab for Neuroinformation, University of Electronic Science and Technology of China, Chengdu 611731, China.
| | - Airui Li
- Department of Neurosurgery, Sichuan Provincial People's Hospital, MOE Key Lab for Neuroinformation, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Mingqi Liu
- Department of Neurosurgery, Sichuan Provincial People's Hospital, MOE Key Lab for Neuroinformation, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Zhaoxin Jian
- Department of Neurosurgery, Sichuan Provincial People's Hospital, MOE Key Lab for Neuroinformation, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Ke Chen
- Department of Neurosurgery, Sichuan Provincial People's Hospital, MOE Key Lab for Neuroinformation, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Dezhong Yao
- Department of Neurosurgery, Sichuan Provincial People's Hospital, MOE Key Lab for Neuroinformation, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Daqing Guo
- Department of Neurosurgery, Sichuan Provincial People's Hospital, MOE Key Lab for Neuroinformation, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Yang Xia
- Department of Neurosurgery, Sichuan Provincial People's Hospital, MOE Key Lab for Neuroinformation, University of Electronic Science and Technology of China, Chengdu 611731, China.
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4
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Avoli M, Chen LY, Di Cristo G, Librizzi L, Scalmani P, Shiri Z, Uva L, de Curtis M, Lévesque M. Ligand-gated mechanisms leading to ictogenesis in focal epileptic disorders. Neurobiol Dis 2023; 180:106097. [PMID: 36967064 DOI: 10.1016/j.nbd.2023.106097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 03/14/2023] [Accepted: 03/22/2023] [Indexed: 04/03/2023] Open
Abstract
We review here the neuronal mechanisms that cause seizures in focal epileptic disorders and, specifically, those involving limbic structures that are known to be implicated in human mesial temporal lobe epilepsy. In both epileptic patients and animal models, the initiation of focal seizures - which are most often characterized by a low-voltage fast onset EEG pattern - is presumably dependent on the synchronous firing of GABA-releasing interneurons that, by activating post-synaptic GABAA receptors, cause large increases in extracellular [K+] through the activation of the co-transporter KCC2. A similar mechanism may contribute to seizure maintenance; accordingly, inhibiting KCC2 activity transforms seizure activity into a continuous pattern of short-lasting epileptiform discharges. It has also been found that interactions between different areas of the limbic system modulate seizure occurrence by controlling extracellular [K+] homeostasis. In line with this view, low-frequency electrical or optogenetic activation of limbic networks restrain seizure generation, an effect that may also involve the activation of GABAB receptors and activity-dependent changes in epileptiform synchronization. Overall, these findings highlight the paradoxical role of GABAA signaling in both focal seizure generation and maintenance, emphasize the efficacy of low-frequency activation in abating seizures, and provide experimental evidence explaining the poor efficacy of antiepileptic drugs designed to augment GABAergic function in controlling seizures in focal epileptic disorders.
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Affiliation(s)
- Massimo Avoli
- Montreal Neurological Institute-Hospital, Departments of Neurology, Canada; Neurology & Neurosurgery and of Physiology, McGill University, Montreal H3A 2B4, Que, Canada.
| | - Li-Yuan Chen
- Montreal Neurological Institute-Hospital, Departments of Neurology, Canada
| | - Graziella Di Cristo
- Neurosciences Department, Université de Montréal, Montréal, Québec H3T 1N8, Canada; CHU Sainte-Justine Research Center, Montréal, Québec H3T 1C5, Canada
| | - Laura Librizzi
- Epilepsy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy
| | - Paolo Scalmani
- Epilepsy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy
| | - Zahra Shiri
- Montreal Neurological Institute-Hospital, Departments of Neurology, Canada
| | - Laura Uva
- Epilepsy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy
| | - Marco de Curtis
- Epilepsy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy
| | - Maxime Lévesque
- Montreal Neurological Institute-Hospital, Departments of Neurology, Canada
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5
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Scalmani P, Paterra R, Mantegazza M, Avoli M, de Curtis M. Involvement of GABAergic Interneuron Subtypes in 4-Aminopyridine-Induced Seizure-Like Events in Mouse Entorhinal Cortex in Vitro. J Neurosci 2023; 43:1987-2001. [PMID: 36810229 PMCID: PMC10027059 DOI: 10.1523/jneurosci.1190-22.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 12/30/2022] [Accepted: 01/05/2023] [Indexed: 02/23/2023] Open
Abstract
Single-unit recordings performed in temporal lobe epilepsy patients and in models of temporal lobe seizures have shown that interneurons are active at focal seizure onset. We performed simultaneous patch-clamp and field potential recordings in entorhinal cortex slices of GAD65 and GAD67 C57BL/6J male mice that express green fluorescent protein in GABAergic neurons to analyze the activity of specific interneuron (IN) subpopulations during acute seizure-like events (SLEs) induced by 4-aminopyridine (4-AP; 100 μm). IN subtypes were identified as parvalbuminergic (INPV, n = 17), cholecystokinergic (INCCK), n = 13], and somatostatinergic (INSOM, n = 15), according to neurophysiological features and single-cell digital PCR. INPV and INCCK discharged at the start of 4-AP-induced SLEs characterized by either low-voltage fast or hyper-synchronous onset pattern. In both SLE onset types, INSOM fired earliest before SLEs, followed by INPV and INCCK discharges. Pyramidal neurons became active with variable delays after SLE onset. Depolarizing block was observed in ∼50% of cells in each INs subgroup, and it was longer in IN (∼4 s) than in pyramidal neurons (<1 s). As SLE evolved, all IN subtypes generated action potential bursts synchronous with the field potential events leading to SLE termination. High-frequency firing throughout the SLE occurred in one-third of INPV and INSOM We conclude that entorhinal cortex INs are very active at the onset and during the progression of SLEs induced by 4-AP. These results support earlier in vivo and in vivo evidence and suggest that INs have a preferential role in focal seizure initiation and development.SIGNIFICANCE STATEMENT Focal seizures are believed to result from enhanced excitation. Nevertheless, we and others demonstrated that cortical GABAergic networks may initiate focal seizures. Here, we analyzed for the first time the role of different IN subtypes in seizures generated by 4-aminopyridine in the mouse entorhinal cortex slices. We found that in this in vitro focal seizure model, all IN types contribute to seizure initiation and that INs precede firing of principal cells. This evidence is in agreement with the active role of GABAergic networks in seizure generation.
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Affiliation(s)
| | - Rosina Paterra
- Neuro-Oncology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano 20133, Italy
| | - Massimo Mantegazza
- Université Côte d'Azur, 06560 Valbonne-Sophia Antipolis, France
- Institute of Molecular and Cellular Pharmacology, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7275, Laboratoire d'Excellence/Canaux Ioniques d'Intérêt Thérapeutique, 06650 Valbonne-Sophia Antipolis, France
- Institut National de la Santé et de la Recherche Médicale, 06650 Valbonne-Sophia Antipolis, France
| | - Massimo Avoli
- Montreal Neurological Institute-Hospital, McGill University, Montreal, Quebec H3A 2B4, Canada
- Departments of Neurology and Neurosurgery and Physiology, McGill University, Montreal, Quebec H3A 2B4, Canada
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6
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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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7
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Curot J, Barbeau E, Despouy E, Denuelle M, Sol JC, Lotterie JA, Valton L, Peyrache A. Local neuronal excitation and global inhibition during epileptic fast ripples in humans. Brain 2022; 146:561-575. [PMID: 36093747 PMCID: PMC9924905 DOI: 10.1093/brain/awac319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 07/01/2022] [Accepted: 08/01/2022] [Indexed: 11/12/2022] Open
Abstract
Understanding the neuronal basis of epileptic activity is a major challenge in neurology. Cellular integration into larger scale networks is all the more challenging. In the local field potential, interictal epileptic discharges can be associated with fast ripples (200-600 Hz), which are a promising marker of the epileptogenic zone. Yet, how neuronal populations in the epileptogenic zone and in healthy tissue are affected by fast ripples remain unclear. Here, we used a novel 'hybrid' macro-micro depth electrode in nine drug-resistant epileptic patients, combining classic depth recording of local field potentials (macro-contacts) and two or three tetrodes (four micro-wires bundled together) enabling up to 15 neurons in local circuits to be simultaneously recorded. We characterized neuronal responses (190 single units) with the timing of fast ripples (2233 fast ripples) on the same hybrid and other electrodes that target other brain regions. Micro-wire recordings reveal signals that are not visible on macro-contacts. While fast ripples detected on the closest macro-contact to the tetrodes were always associated with fast ripples on the tetrodes, 82% of fast ripples detected on tetrodes were associated with detectable fast ripples on the nearest macro-contact. Moreover, neuronal recordings were taken in and outside the epileptogenic zone of implanted epileptic subjects and they revealed an interlay of excitation and inhibition across anatomical scales. While fast ripples were associated with increased neuronal activity in very local circuits only, they were followed by inhibition in large-scale networks (beyond the epileptogenic zone, even in healthy cortex). Neuronal responses to fast ripples were homogeneous in local networks but differed across brain areas. Similarly, post-fast ripple inhibition varied across recording locations and subjects and was shorter than typical inter-fast ripple intervals, suggesting that this inhibition is a fundamental refractory process for the networks. These findings demonstrate that fast ripples engage local and global networks, including healthy tissue, and point to network features that pave the way for new diagnostic and therapeutic strategies. They also reveal how even localized pathological brain dynamics can affect a broad range of cognitive functions.
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Affiliation(s)
- Jonathan Curot
- Correspondence to: Jonathan Curot, MD, PhD CerCo CNRS UMR 5549, Université Toulouse III CHU Purpan, Pavillon Baudot, 31052 Toulouse Cedex, France E-mail:
| | - Emmanuel Barbeau
- Brain and Cognition Research Center (CerCo), Centre National de la Recherche Scientifique, UMR5549, Toulouse, France,Faculty of Health, University of Toulouse, Paul Sabatier University, Toulouse, France
| | - Elodie Despouy
- Brain and Cognition Research Center (CerCo), Centre National de la Recherche Scientifique, UMR5549, Toulouse, France
| | - Marie Denuelle
- Departments of Neurology and Neurosurgery, Toulouse University Hospital, Toulouse, France,Brain and Cognition Research Center (CerCo), Centre National de la Recherche Scientifique, UMR5549, Toulouse, France
| | - Jean Christophe Sol
- Departments of Neurology and Neurosurgery, Toulouse University Hospital, Toulouse, France,Faculty of Health, University of Toulouse, Paul Sabatier University, Toulouse, France,Toulouse Neuro Imaging Center (ToNIC), INSERM, U1214, Toulouse, France
| | - Jean-Albert Lotterie
- Departments of Neurology and Neurosurgery, Toulouse University Hospital, Toulouse, France,Toulouse Neuro Imaging Center (ToNIC), INSERM, U1214, Toulouse, France
| | - Luc Valton
- Departments of Neurology and Neurosurgery, Toulouse University Hospital, Toulouse, France,Brain and Cognition Research Center (CerCo), Centre National de la Recherche Scientifique, UMR5549, Toulouse, France
| | - Adrien Peyrache
- Correspondence may also be addressed to: Adrien Peyrache, PhD Montreal Neurological Institute Department of Neurology and Neurosurgery McGill University, 3810 University Street Montreal, Quebec, Canada E-mail:
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8
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Wang S, Kfoury C, Marion A, Lévesque M, Avoli M. Modulation of in vitro epileptiform activity by optogenetic stimulation of parvalbumin-positive interneurons. J Neurophysiol 2022; 128:837-846. [PMID: 36043700 DOI: 10.1152/jn.00192.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
GABAA signaling is surprisingly involved in the initiation of epileptiform activity since increased interneuron firing, presumably leading to excessive GABA release, often precedes ictal discharges. Field potential theta (4-12 Hz) oscillations, which are thought to mirror the synchronization of interneuron networks, also lead to ictogenesis. However, the exact role of parvalbumin-positive (PV) interneurons in generating theta oscillations linked to epileptiform discharges remains unexplored. We analyzed here the field responses recorded in the CA3, entorhinal cortex (EC) and dentate gyrus (DG) during 8 Hz optogenetic stimulation of PV-positive interneurons in brain slices obtained from PV-ChR2 mice during 4-aminopyridine (4AP) application. This optogenetic protocol triggered similar field oscillations in both control conditions and during 4AP application. However, in the presence of 4AP, optogenetic stimuli also induced: (i) interictal discharges that were associated in all regions with 8 Hz field oscillations; and (ii) low-voltage fast onset ictal discharges. Interictal and ictal events occurred more frequently during optogenetic activation than during periods of no stimulation. 4AP also increased synchronicity during PV-interneuron activation in all three regions. In opsin-negative mice, optogenetic stimulation did not change the rate of both types of epileptiform activity. Our findings suggest that PV-interneuron recruitment at theta (8 Hz) frequency contributes to epileptiform synchronization in limbic structures in the in vitro 4AP model.
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Affiliation(s)
- Siyan Wang
- Montreal Neurological Institute and Hospital and Departments of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
| | - Cristen Kfoury
- Montreal Neurological Institute and Hospital and Departments of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada.,Department of Physiology, McGill University, Montreal, QC, Canada
| | - Alexis Marion
- Montreal Neurological Institute and Hospital and Departments of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada.,Department of Physiology, McGill University, Montreal, QC, Canada
| | - Maxime Lévesque
- Montreal Neurological Institute and Hospital and Departments of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
| | - Massimo Avoli
- Montreal Neurological Institute and Hospital and Departments of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada.,Department of Physiology, McGill University, Montreal, QC, Canada
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9
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Weiss SA, Pastore T, Orosz I, Rubinstein D, Gorniak R, Waldman Z, Fried I, Wu C, Sharan A, Slezak D, Worrell G, Engel J, Sperling MR, Staba RJ. Graph theoretical measures of fast ripples support the epileptic network hypothesis. Brain Commun 2022; 4:fcac101. [PMID: 35620169 PMCID: PMC9128387 DOI: 10.1093/braincomms/fcac101] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Revised: 02/10/2022] [Accepted: 04/12/2022] [Indexed: 11/16/2022] Open
Abstract
The epileptic network hypothesis and epileptogenic zone hypothesis are two
theories of ictogenesis. The network hypothesis posits that coordinated activity
among interconnected nodes produces seizures. The epileptogenic zone hypothesis
posits that distinct regions are necessary and sufficient for seizure
generation. High-frequency oscillations, and particularly fast ripples, are
thought to be biomarkers of the epileptogenic zone. We sought to test these
theories by comparing high-frequency oscillation rates and networks in surgical
responders and non-responders, with no appreciable change in seizure frequency
or severity, within a retrospective cohort of 48 patients implanted with
stereo-EEG electrodes. We recorded inter-ictal activity during non-rapid eye
movement sleep and semi-automatically detected and quantified high-frequency
oscillations. Each electrode contact was localized in normalized coordinates. We
found that the accuracy of seizure onset zone electrode contact classification
using high-frequency oscillation rates was not significantly different in
surgical responders and non-responders, suggesting that in non-responders the
epileptogenic zone partially encompassed the seizure onset zone(s)
(P > 0.05). We also found that in the
responders, fast ripple on oscillations exhibited a higher spectral content in
the seizure onset zone compared with the non-seizure onset zone
(P < 1 × 10−5).
By contrast, in the non-responders, fast ripple had a lower spectral content in
the seizure onset zone
(P < 1 × 10−5).
We constructed two different networks of fast ripple with a spectral content
>350 Hz. The first was a rate–distance network that
multiplied the Euclidian distance between fast ripple-generating contacts by the
average rate of fast ripple in the two contacts. The radius of the
rate–distance network, which excluded seizure onset zone nodes,
discriminated non-responders, including patients not offered resection or
responsive neurostimulation due to diffuse multifocal onsets, with an accuracy
of 0.77 [95% confidence interval (CI) 0.56–0.98]. The second fast
ripple network was constructed using the mutual information between the timing
of the events to measure functional connectivity. For most non-responders, this
network had a longer characteristic path length, lower mean local efficiency in
the non-seizure onset zone, and a higher nodal strength among non-seizure onset
zone nodes relative to seizure onset zone nodes. The graphical theoretical
measures from the rate–distance and mutual information networks of 22
non- responsive neurostimulation treated patients was used to train a support
vector machine, which when tested on 13 distinct patients classified
non-responders with an accuracy of 0.92 (95% CI 0.75–1). These
results indicate patients who do not respond to surgery or those not selected
for resection or responsive neurostimulation can be explained by the epileptic
network hypothesis that is a decentralized network consisting of widely
distributed, hyperexcitable fast ripple-generating nodes.
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Affiliation(s)
- Shennan A Weiss
- Dept. of Neurology, State University of New York Downstate, Brooklyn, New York, 11203 USA
- Dept. of Physiology and Pharmacology, State University of New York Downstate, Brooklyn, New York, 11203 USA
- Dept. of Neurology, New York City Health + Hospitals/Kings County, Brooklyn, NY, USA
| | - Tomas Pastore
- Dept. of Computer Science, University of Buenos Aires, Buenos Aires, Argentina
| | - Iren Orosz
- Dept. of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California, 90095, USA
| | - Daniel Rubinstein
- Depts. of Neurology and Neuroscience, Thomas Jefferson University, Philadelphia, Pennsylvania, 19107, USA
| | - Richard Gorniak
- Dept. of Neuroradiology, Thomas Jefferson University, Philadelphia, Pennsylvania, 19107, USA
| | - Zachary Waldman
- Depts. of Neurology and Neuroscience, Thomas Jefferson University, Philadelphia, Pennsylvania, 19107, USA
| | - Itzhak Fried
- Dept. of Neurosurgery, David Geffen School of Medicine at UCLA, Los Angeles, California, 90095, USA
| | - Chengyuan Wu
- Dept. of Neurosurgery, Thomas Jefferson University, Philadelphia, Pennsylvania, 19107, USA
| | - Ashwini Sharan
- Dept. of Neurosurgery, Thomas Jefferson University, Philadelphia, Pennsylvania, 19107, USA
| | - Diego Slezak
- Dept. of Computer Science, University of Buenos Aires, Buenos Aires, Argentina
| | - Gregory Worrell
- Dept. of Neurology, Mayo Systems Electrophysiology Laboratory (MSEL), USA
- Dept. of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA
| | - Jerome Engel
- Dept. of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California, 90095, USA
- Dept. of Neurosurgery, David Geffen School of Medicine at UCLA, Los Angeles, California, 90095, USA
- Dept. of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, California, 90095, USA
- Dept. of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at UCLA, Los Angeles, California, 90095, USA
- Brain Research Institute, David Geffen School of Medicine at UCLA, Los Angeles, California, 90095, USA
| | - Michael R. Sperling
- Depts. of Neurology and Neuroscience, Thomas Jefferson University, Philadelphia, Pennsylvania, 19107, USA
| | - Richard J Staba
- Dept. of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California, 90095, USA
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10
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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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11
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Cherubini E, Di Cristo G, Avoli M. Dysregulation of GABAergic Signaling in Neurodevelomental Disorders: Targeting Cation-Chloride Co-transporters to Re-establish a Proper E/I Balance. Front Cell Neurosci 2022; 15:813441. [PMID: 35069119 PMCID: PMC8766311 DOI: 10.3389/fncel.2021.813441] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 11/30/2021] [Indexed: 01/01/2023] Open
Abstract
The construction of the brain relies on a series of well-defined genetically and experience- or activity -dependent mechanisms which allow to adapt to the external environment. Disruption of these processes leads to neurological and psychiatric disorders, which in many cases are manifest already early in postnatal life. GABA, the main inhibitory neurotransmitter in the adult brain is one of the major players in the early assembly and formation of neuronal circuits. In the prenatal and immediate postnatal period GABA, acting on GABAA receptors, depolarizes and excites targeted cells via an outwardly directed flux of chloride. In this way it activates NMDA receptors and voltage-dependent calcium channels contributing, through intracellular calcium rise, to shape neuronal activity and to establish, through the formation of new synapses and elimination of others, adult neuronal circuits. The direction of GABAA-mediated neurotransmission (depolarizing or hyperpolarizing) depends on the intracellular levels of chloride [Cl−]i, which in turn are maintained by the activity of the cation-chloride importer and exporter KCC2 and NKCC1, respectively. Thus, the premature hyperpolarizing action of GABA or its persistent depolarizing effect beyond the postnatal period, leads to behavioral deficits associated with morphological alterations and an excitatory (E)/inhibitory (I) imbalance in selective brain areas. The aim of this review is to summarize recent data concerning the functional role of GABAergic transmission in building up and refining neuronal circuits early in development and its dysfunction in neurodevelopmental disorders such as Autism Spectrum Disorders (ASDs), schizophrenia and epilepsy. In particular, we focus on novel information concerning the mechanisms by which alterations in cation-chloride co-transporters (CCC) generate behavioral and cognitive impairment in these diseases. We discuss also the possibility to re-establish a proper GABAA-mediated neurotransmission and excitatory (E)/inhibitory (I) balance within selective brain areas acting on CCC.
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Affiliation(s)
- Enrico Cherubini
- European Brain Research Institute (EBRI)-Rita Levi-Montalcini, Roma, Italy
- *Correspondence: Enrico Cherubini
| | - Graziella Di Cristo
- Neurosciences Department, Université de Montréal and CHU Sainte-Justine Research Center, Montreal, QC, Canada
| | - Massimo Avoli
- Montreal Neurological Institute-Hospital and Departments of Neurology and Neurosurgery and of Physiology, McGill University, Montreal, QC, Canada
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12
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Wang S, Zhang X, Zhou L, Wu Q, Han Y. Analysis of GABRG2 C588T polymorphism in genetic epilepsy and evaluation of GABRG2 in drug treatment. Clin Transl Sci 2021; 14:1725-1733. [PMID: 33650258 PMCID: PMC8504831 DOI: 10.1111/cts.12997] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 01/07/2021] [Accepted: 01/07/2021] [Indexed: 01/11/2023] Open
Abstract
Epilepsy is a common disorder with complex inheritance, and its treatment is very unsatisfactory. An association between the GABRG2 C588T polymorphism and genetic generalized epilepsy has been studied by several genetic association studies. However, these results were inconsistent, and the role of GABRG2 in epilepsy treatment remains unknown. To evaluate the role of GABRG2 in epilepsy, we performed meta-analysis, expression quantitative trait loci analysis, protein-protein interaction analysis, and drug-gene interaction analysis. The combined results indicated that the GABRG2 C588T polymorphism was associated with genetic generalized epilepsy risk under dominant and allelic models (odds ratio [OR] = 1.25, 95% confidence interval [CI] = 1.02-1.54, p = 0.03, I2 = 0% and OR = 1.21, 95% CI = 1.03-1.42, p = 0.02, I2 = 20%, respectively). In the Asian population, we also found similar results under dominant and allelic models (OR = 1.93, 95% CI = 1.18-3.16, p = 0.009, I2 = 0% and OR = 1.69, 95% CI = 1.20-2.37, p = 0.003, I2 = 11%, respectively). We first found that the GABRG2 C588T polymorphism regulates GABRG2 expression in human brain tissues and that the protein encoded by GABRG2 interacts with targets of approved antiepileptic drugs (AEDs). Interestingly, we also found that GABRG2 itself interacts with approved AEDs. Taken together, the results indicate that the C588T polymorphism might alter the GABAA receptor by modulating GABRG2 gene expression, resulting in increased risk for epilepsy, and that GABRG2 may be a potential therapeutic target for epilepsy.
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Affiliation(s)
- Shitao Wang
- Department of Neurology, The First Affiliated Hospital of Kunming Medical University, Kunming, China
| | - Xianjun Zhang
- Department of Neurology, The First Affiliated Hospital of Kunming Medical University, Kunming, China
| | - Liang Zhou
- Department of Neurology, The First Affiliated Hospital of Kunming Medical University, Kunming, China
| | - Qian Wu
- Department of Neurology, The First Affiliated Hospital of Kunming Medical University, Kunming, China
| | - Yanbing Han
- Department of Neurology, The First Affiliated Hospital of Kunming Medical University, Kunming, China
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13
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Chiprés-Tinajero GA, Núñez-Ochoa MA, Medina-Ceja L. Increased immunoreactivity of glutamate receptors, neuronal nuclear protein and glial fibrillary acidic protein in the hippocampus of epileptic rats with fast ripple activity. Exp Brain Res 2021; 239:2015-2024. [PMID: 33909110 DOI: 10.1007/s00221-021-06108-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 04/08/2021] [Indexed: 11/28/2022]
Abstract
Epilepsy is a neurological disorder in which an imbalance between excitatory and inhibitory transmission is observed. Glutamate is the principal excitatory neurotransmitter that acts through ionic and metabotropic receptors; both types of receptors are involved in temporal lobe epilepsy (TLE). High frequency oscillations called fast ripples (FR, 250-600 Hz) have been observed, particularly in the hippocampus, and they are involved in epileptogenesis. The present study analyzed the immunoreactivity of the principal glutamate receptors associated with epilepsy in epileptic animals with FR activity. Male Swiss-Wistar rats (210-250 gr) were injected with pilocarpine (2.4 mg/2 µl) and were video monitored (24/7) until the appearance of spontaneous and recurrent seizures. Then, a deep microelectrode implantation surgery was performed in the DG, CA3 and CA1 regions, and FR activity was observed 1-, 2-, 3-, 7-, and 14-day postsurgery. The animals were sacrificed on day 15, and fluorescence immunohistochemistry was carried out in the hippocampus for the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), N-methyl-D-aspartate (NMDA) and mGlu-R5 glutamate receptors as well as Neuronal Nuclear Protein (NeuN) and Glial Fibrillary Acidic Protein (GFAP). An increase in the immunoreactivity for the three receptors was found. However, the AMPA receptor showed an increase in the three regions analyzed (i.e., DG, CA1 and CA3). The findings showed a decrease of NeuN in the DG and an increase of GFAP. These results suggest an important role of glutamate receptors in the hippocampus of epileptic rats with FR activity.
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Affiliation(s)
- Gustavo A Chiprés-Tinajero
- Laboratory of Neurophysiology, Department of Cellular and Molecular Biology, CUCBA, University of Guadalajara, Camino Ing. R. Padilla Sánchez 2100, Las Agujas, Nextipac, Zapopan, Jalisco, 45110, México
| | - Miguel A Núñez-Ochoa
- Laboratory of Neurophysiology, Department of Cellular and Molecular Biology, CUCBA, University of Guadalajara, Camino Ing. R. Padilla Sánchez 2100, Las Agujas, Nextipac, Zapopan, Jalisco, 45110, México
| | - Laura Medina-Ceja
- Laboratory of Neurophysiology, Department of Cellular and Molecular Biology, CUCBA, University of Guadalajara, Camino Ing. R. Padilla Sánchez 2100, Las Agujas, Nextipac, Zapopan, Jalisco, 45110, México.
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14
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Lucchi C, Costa AM, Rustichelli C, Biagini G. Allopregnanolone and Pregnanolone Are Reduced in the Hippocampus of Epileptic Rats, but Only Allopregnanolone Correlates with Seizure Frequency. Neuroendocrinology 2021; 111:536-541. [PMID: 32492675 DOI: 10.1159/000509093] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 06/02/2020] [Indexed: 11/19/2022]
Abstract
BACKGROUND Neurosteroids modulate epileptic activity by interacting with the γ-aminobutyric acid type A receptor, but their brain levels are still undetermined. OBJECTIVES We aimed to establish neurosteroid levels in the neocortex and hippocampus by liquid chromatography/mass spectrometry in epileptic rats. METHODS Kainic acid-treated rats were continuously monitored up to 9 weeks to determine seizure frequency by video electrocorticography (n = 23) and compared to age-matched controls monitored in the same manner (n = 11). RESULTS Decreased allopregnanolone (-50%; p < 0.05, Mann-Whitney test) and pregnanolone levels (-64%; p < 0.01) were found in the hippocampus, whereas pregnenolone sulfate, pregnenolone, progesterone, and 5α-dihydroprogesterone were nonsignificantly reduced. No changes were found in the neocortex. Moreover, allopregnanolone (but not pregnanolone) levels were positively correlated with seizure frequency (r2 = 0.4606, p < 0.01). CONCLUSION These findings indicate a selective reduction in hippocampal levels of 3α-reduced neurosteroids. This reduction was partially mitigated by seizures in the case of allopregnanolone.
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Affiliation(s)
- Chiara Lucchi
- Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Anna Maria Costa
- Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Cecilia Rustichelli
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Giuseppe Biagini
- Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy,
- Center for Neuroscience and Neurotechnology, University of Modena and Reggio Emilia, Modena, Italy,
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15
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Neuronal Firing and Waveform Alterations through Ictal Recruitment in Humans. J Neurosci 2020; 41:766-779. [PMID: 33229500 DOI: 10.1523/jneurosci.0417-20.2020] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 10/29/2020] [Accepted: 11/11/2020] [Indexed: 01/04/2023] Open
Abstract
Analyzing neuronal activity during human seizures is pivotal to understanding mechanisms of seizure onset and propagation. These analyses, however, invariably using extracellular recordings, are greatly hindered by various phenomena that are well established in animal studies: changes in local ionic concentration, changes in ionic conductance, and intense, hypersynchronous firing. The first two alter the action potential waveform, whereas the third increases the "noise"; all three factors confound attempts to detect and classify single neurons. To address these analytical difficulties, we developed a novel template-matching-based spike sorting method, which enabled identification of 1239 single neurons in 27 patients (13 female) with intractable focal epilepsy, that were tracked throughout multiple seizures. These new analyses showed continued neuronal firing with widespread intense activation and stereotyped action potential alterations in tissue that was invaded by the seizure: neurons displayed increased waveform duration (p < 0.001) and reduced amplitude (p < 0.001), consistent with prior animal studies. By contrast, neurons in "penumbral" regions (those receiving intense local synaptic drive from the seizure but without neuronal evidence of local seizure invasion) showed stable waveforms. All neurons returned to their preictal waveforms after seizure termination. We conclude that the distinction between "core" territories invaded by the seizure versus "penumbral" territories is evident at the level of single neurons. Furthermore, the increased waveform duration and decreased waveform amplitude are neuron-intrinsic hallmarks of seizure invasion that impede traditional spike sorting and could be used as defining characteristics of local recruitment.SIGNIFICANCE STATEMENT Animal studies consistently show marked changes in action potential waveform during epileptic discharges, but acquiring similar evidence in humans has proven difficult. Assessing neuronal involvement in ictal events is pivotal to understanding seizure dynamics and in defining clinical localization of epileptic pathology. Using a novel method to track neuronal firing, we analyzed microelectrode array recordings of spontaneously occurring human seizures, and here report two dichotomous activity patterns. In cortex that is recruited to the seizure, neuronal firing rates increase and waveforms become longer in duration and shorter in amplitude as the neurons are recruited to the seizure, while penumbral tissue shows stable action potentials, in keeping with the "dual territory" model of seizure dynamics.
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16
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Yang YC, Wang GH, Chuang AY, Hsueh SW. Perampanel reduces paroxysmal depolarizing shift and inhibitory synaptic input in excitatory neurons to inhibit epileptic network oscillations. Br J Pharmacol 2020; 177:5177-5194. [PMID: 32901915 DOI: 10.1111/bph.15253] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 08/10/2020] [Accepted: 08/28/2020] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND AND PURPOSE Perampanel is a newly approved anticonvulsant uniquely targeting AMPA receptors, which mediate the most abundant form of excitatory synaptic transmission in the brain. However, the network mechanism underlying the anti-epileptic effect of the AMPAergic inhibition remains to be explored. EXPERIMENTAL APPROACH The mechanism of perampanel action was studied with the basolateral amygdala network containing pyramidal-inhibitory neuronal resonators in seizure models of 4-aminopyridine (4-AP) and electrical kindling. KEY RESULTS Application of either 4-AP or electrical kindling to the basolateral amygdala readily induces AMPAergic transmission-dependent reverberating activities between pyramidal-inhibitory neuronal resonators, which are chiefly characterized by burst discharges in inhibitory neurons and corresponding recurrent inhibitory postsynaptic potentials in pyramidal neurons. Perampanel reduces post-kindling "paroxysmal depolarizing shift" especially in pyramidal neurons and, counterintuitively, eliminates burst activities in inhibitory neurons and inhibitory synaptic inputs onto excitatory pyramidal neurons to result in prevention of epileptiform discharges and seizure behaviours. Intriguingly, similar effects can be obtained with not only the AMPA receptor antagonist CNQX but also the GABAA receptor antagonist bicuculline, which is usually considered as a proconvulsant. CONCLUSION AND IMPLICATIONS Ictogenesis depends on the AMPA receptor-dependent recruitment of pyramidal-inhibitory neuronal network oscillations tuned by dynamic glutamatergic and GABAergic transmission. The anticonvulsant effect of perampanel then stems from disruption of the coordinated network activities rather than simply decreased neuronal excitability or excitatory transmission. Positive or negative modulation of epileptic network reverberations may be pro-ictogenic or anti-ictogenic, respectively, constituting a more applicable rationale for the therapy against seizures.
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Affiliation(s)
- Ya-Chin Yang
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan.,Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan.,Neuroscience Research Center, Chang Gung Memorial Hospital, Linkou Medical Center, Taoyuan, Taiwan
| | - Guan-Hsun Wang
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan.,School of Medicine, College of Medicine, Chang Gung University, Taoyuan, Taiwan.,Department of Medical Education, Chang Gung Memorial Hospital, Linkou Medical Center, Taoyuan, Taiwan
| | - Ai-Yu Chuang
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Shu-Wei Hsueh
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
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17
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Kapinos G, Desai MJ, Weiss SA, Valsamis HA. Biochemical underpinning of Lateralized Periodic Discharges: Regional glutamate overload? Epilepsy Res 2020; 167:106442. [PMID: 32916643 DOI: 10.1016/j.eplepsyres.2020.106442] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 08/11/2020] [Accepted: 08/13/2020] [Indexed: 10/23/2022]
Affiliation(s)
- Gregory Kapinos
- Departments of Neurology, Neurosurgery & Emergency Medicine, New York City Health + Hospitals / Kings County, Brooklyn, NY, United States; Department of Neurology, State University of New York Downstate Health Sciences University College of Medicine, Brooklyn, NY, United States.
| | - Masoom J Desai
- Division of Critical Care Neurology and Division of Epilepsy & Neurophysiology, Department of Neurology, University of Oklahoma Health Science Center, United States
| | - Shennan A Weiss
- Department of Neurology, Brookdale Hospital Medical Center, Brooklyn, NY, United States
| | - Helen A Valsamis
- Department of Neurology, New York City Health + Hospitals / Kings County, Brooklyn, NY, United States; Department of Neurology, State University of New York Downstate Medical Center, Brooklyn, NY, United States
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18
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Cepeda C, Levinson S, Nariai H, Yazon VW, Tran C, Barry J, Oikonomou KD, Vinters HV, Fallah A, Mathern GW, Wu JY. Pathological high frequency oscillations associate with increased GABA synaptic activity in pediatric epilepsy surgery patients. Neurobiol Dis 2019; 134:104618. [PMID: 31629890 DOI: 10.1016/j.nbd.2019.104618] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 08/22/2019] [Accepted: 09/19/2019] [Indexed: 11/25/2022] Open
Abstract
Pathological high-frequency oscillations (HFOs), specifically fast ripples (FRs, >250 Hz), are pathognomonic of an active epileptogenic zone. However, the origin of FRs remains unknown. Here we explored the correlation between FRs recorded with intraoperative pre-resection electrocorticography (ECoG) and spontaneous synaptic activity recorded ex vivo from cortical tissue samples resected for the treatment of pharmacoresistant epilepsy. The cohort included 47 children (ages 0.22-9.99 yr) with focal cortical dysplasias (CD types I and II), tuberous sclerosis complex (TSC) and non-CD pathologies. Whole-cell patch clamp recordings were obtained from pyramidal neurons and interneurons in cortical regions that were positive or negative for pathological HFOs, defined as FR band oscillations (250-500 Hz) at ECoG. The frequency of spontaneous excitatory and inhibitory postsynaptic currents (sEPSCs and IPSCs, respectively) was compared between HFO+ and HFO- regions. Regardless of pathological substrate, regions positive for FRs displayed significantly increased frequencies of sIPSCs compared with regions negative for FRs. In contrast, the frequency of sEPSCs was similar in both regions. In about one third of cases (n = 17), pacemaker GABA synaptic activity (PGA) was observed. In the vast majority (n = 15), PGA occurred in HFO+ areas. Further, fast-spiking interneurons displayed signs of hyperexcitability exclusively in HFO+ areas. These results indicate that, in pediatric epilepsy patients, increased GABA synaptic activity is associated with interictal FRs in the epileptogenic zone and suggest an active role of GABAergic interneurons in the generation of pathological HFOs. Increased GABA synaptic activity could serve to dampen excessive excitability of cortical pyramidal neurons in the epileptogenic zone, but it could also promote neuronal network synchrony.
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Affiliation(s)
- Carlos Cepeda
- IDDRC, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA.
| | - Simon Levinson
- IDDRC, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Hiroki Nariai
- Division of Pediatric Neurology, Mattel Children's Hospital, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Vannah-Wila Yazon
- IDDRC, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Conny Tran
- IDDRC, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Joshua Barry
- IDDRC, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Katerina D Oikonomou
- IDDRC, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Harry V Vinters
- Section of Neuropathology, Department of Pathology and Laboratory Medicine and Department of Neurology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Aria Fallah
- Department of Neurosurgery, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Gary W Mathern
- IDDRC, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA; Department of Neurosurgery, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Joyce Y Wu
- Division of Pediatric Neurology, Mattel Children's Hospital, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
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19
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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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20
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Schevon CA, Tobochnik S, Eissa T, Merricks E, Gill B, Parrish RR, Bateman LM, McKhann GM, Emerson RG, Trevelyan AJ. Multiscale recordings reveal the dynamic spatial structure of human seizures. Neurobiol Dis 2019; 127:303-311. [PMID: 30898669 PMCID: PMC6588430 DOI: 10.1016/j.nbd.2019.03.015] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 03/11/2019] [Accepted: 03/15/2019] [Indexed: 02/07/2023] Open
Abstract
The cellular activity underlying human focal seizures, and its relationship to key signatures in the EEG recordings used for therapeutic purposes, has not been well characterized despite many years of investigation both in laboratory and clinical settings. The increasing use of microelectrodes in epilepsy surgery patients has made it possible to apply principles derived from laboratory research to the problem of mapping the spatiotemporal structure of human focal seizures, and characterizing the corresponding EEG signatures. In this review, we describe results from human microelectrode studies, discuss some data interpretation pitfalls, and explain the current understanding of the key mechanisms of ictogenesis and seizure spread.
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Affiliation(s)
- Catherine A Schevon
- Department of Neurology, Columbia University Medical Center, New York, NY, USA.
| | - Steven Tobochnik
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Tahra Eissa
- Department of Applied Mathematics, University of Colorado at Boulder, Boulder, CO, USA
| | - Edward Merricks
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Brian Gill
- Department of Neurological Surgery, Columbia University Medical Center, New York, NY, USA
| | - R Ryley Parrish
- Institute for Aging, Newcastle University, Newcastle-Upon-Tyne, UK
| | - Lisa M Bateman
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Guy M McKhann
- Department of Neurological Surgery, Columbia University Medical Center, New York, NY, USA
| | - Ronald G Emerson
- Department of Neurology, Weill Cornell Medical Center, New York, NY, USA
| | - Andrew J Trevelyan
- Department of Neurology, Columbia University Medical Center, New York, NY, USA; Institute for Aging, Newcastle University, Newcastle-Upon-Tyne, UK
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21
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Schönberger J, Frauscher B, von Ellenrieder N, Avoli M, Dubeau F, Gotman J. Fast ripple analysis in human mesial temporal lobe epilepsy suggests two different seizure-generating mechanisms. Neurobiol Dis 2019; 127:374-381. [DOI: 10.1016/j.nbd.2019.03.030] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 03/19/2019] [Accepted: 03/26/2019] [Indexed: 12/16/2022] Open
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22
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Electrophysiological monitoring of inhibition in mammalian species, from rodents to humans. Neurobiol Dis 2019; 130:104500. [PMID: 31195126 DOI: 10.1016/j.nbd.2019.104500] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 05/31/2019] [Accepted: 06/06/2019] [Indexed: 01/20/2023] Open
Abstract
GABAergic interneurons constitute a highly diverse family of neurons that play a critical role in cortical functions. Due to their prominent role in cortical network dynamics, genetic, developmental, or other dysfunctions in GABAergic neurons have been linked to neurological disorders such as epilepsy. Thus, it is crucial to investigate the interaction of these various neurons and to develop methods to specifically and directly monitor inhibitory activity in vivo. While research in small mammals has benefited from a wealth of recent technological development, bridging the gap to large mammals and humans remains a challenge. This is of particular interest since single neuron monitoring with intracranial electrodes in epileptic patients is developing quickly, opening new avenues for understanding the role of different cell types in epilepsy. Here, we review currently available techniques that monitor inhibitory activity in the brain and the respective validations in rodents. Finally, we discuss the future developments of these techniques and how knowledge from animal research can be translated to the study of neuronal circuit dynamics in the human brain.
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23
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Avoli M. Inhibition, oscillations and focal seizures: An overview inspired by some historical notes. Neurobiol Dis 2019; 130:104478. [PMID: 31125597 DOI: 10.1016/j.nbd.2019.104478] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
GABA (i.e., γ-amino-butyric acid) is the main inhibitory neurotransmitter in the adult mammalian brain. Once released from inhibitory cells, it activates pre- and post-synaptic GABA receptors that have been categorized into type A and type B. GABAA receptors open ionotropic anionic channels while GABAB receptors are metabotropic, acting through second messengers. In the 1980s, decreased GABA receptor signaling was considered an appealing factor in making cortical neurons generate synchronous epileptiform oscillations and thus a good, perhaps obvious, candidate for causing focal epileptic disorders. However, studies published during the last four decades have demonstrated that interneuron firing - which causes GABA release and thus GABAA receptor activation - can lead to the generation of both physiological (e.g., theta and gamma oscillations or sharp wave-ripples) and pathological oscillations including focal interictal spikes, high frequency oscillations and seizures. Taken together, the reviews published in this special issue of Neurobiology of Disease highlight the key role of inhibition, and in particular of GABAA receptor signaling, in neuronal network functions under physiological and pathological conditions that include epilepsy and Alzheimer's disease.
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Affiliation(s)
- Massimo Avoli
- Montreal Neurological Institute, McGill University, Montreal, H3A 2B4, QC, Canada; Department of Neurology & Neurosurgery, McGill University, Montreal, H3A 2B4, QC, Canada; Department of Experimental Medicine, Facoltà di Medicina e Odontoiatria, Sapienza University of Rome, 00185 Roma, Italy; Department of Physiology, McGill University, Montreal, H3A 2B4, QC, Canada.
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