1
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Neumann AM, Britsch S. Molecular Genetics of Acquired Temporal Lobe Epilepsy. Biomolecules 2024; 14:669. [PMID: 38927072 PMCID: PMC11202058 DOI: 10.3390/biom14060669] [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: 05/07/2024] [Revised: 06/02/2024] [Accepted: 06/03/2024] [Indexed: 06/28/2024] Open
Abstract
An epilepsy diagnosis reduces a patient's quality of life tremendously, and it is a fate shared by over 50 million people worldwide. Temporal lobe epilepsy (TLE) is largely considered a nongenetic or acquired form of epilepsy that develops in consequence of neuronal trauma by injury, malformations, inflammation, or a prolonged (febrile) seizure. Although extensive research has been conducted to understand the process of epileptogenesis, a therapeutic approach to stop its manifestation or to reliably cure the disease has yet to be developed. In this review, we briefly summarize the current literature predominately based on data from excitotoxic rodent models on the cellular events proposed to drive epileptogenesis and thoroughly discuss the major molecular pathways involved, with a focus on neurogenesis-related processes and transcription factors. Furthermore, recent investigations emphasized the role of the genetic background for the acquisition of epilepsy, including variants of neurodevelopmental genes. Mutations in associated transcription factors may have the potential to innately increase the vulnerability of the hippocampus to develop epilepsy following an injury-an emerging perspective on the epileptogenic process in acquired forms of epilepsy.
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Affiliation(s)
| | - Stefan Britsch
- Institute of Molecular and Cellular Anatomy, Ulm University, 89081 Ulm, Germany;
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2
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Agopyan-Miu AH, Merricks EM, Smith EH, McKhann GM, Sheth SA, Feldstein NA, Trevelyan AJ, Schevon CA. Cell-type specific and multiscale dynamics of human focal seizures in limbic structures. Brain 2023; 146:5209-5223. [PMID: 37536281 PMCID: PMC10689922 DOI: 10.1093/brain/awad262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2023] [Revised: 06/30/2023] [Accepted: 07/19/2023] [Indexed: 08/05/2023] Open
Abstract
The relationship between clinically accessible epileptic biomarkers and neuronal activity underlying the transition to seizure is complex, potentially leading to imprecise delineation of epileptogenic brain areas. In particular, the pattern of interneuronal firing at seizure onset remains under debate, with some studies demonstrating increased firing and others suggesting reductions. Previous study of neocortical sites suggests that seizure recruitment occurs upon failure of inhibition, with intact feedforward inhibition in non-recruited territories. We investigated whether the same principle applies in limbic structures. We analysed simultaneous electrocorticography (ECoG) and neuronal recordings of 34 seizures in a cohort of 19 patients (10 male, 9 female) undergoing surgical evaluation for pharmacoresistant focal epilepsy. A clustering approach with five quantitative metrics computed from ECoG and multiunit data was used to distinguish three types of site-specific activity patterns during seizures, which at times co-existed within seizures. Overall, 156 single units were isolated, subclassified by cell-type and tracked through the seizure using our previously published methods to account for impacts of increased noise and single-unit waveshape changes caused by seizures. One cluster was closely associated with clinically defined seizure onset or spread. Entrainment of high-gamma activity to low-frequency ictal rhythms was the only metric that reliably identified this cluster at the level of individual seizures (P < 0.001). A second cluster demonstrated multi-unit characteristics resembling those in the first cluster, without concomitant high-gamma entrainment, suggesting feedforward effects from the seizure. The last cluster captured regions apparently unaffected by the ongoing seizure. Across all territories, the majority of both excitatory and inhibitory neurons reduced (69.2%) or ceased firing (21.8%). Transient increases in interneuronal firing rates were rare (13.5%) but showed evidence of intact feedforward inhibition, with maximal firing rate increases and waveshape deformations in territories not fully recruited but showing feedforward activity from the seizure, and a shift to burst-firing in seizure-recruited territories (P = 0.014). This study provides evidence for entrained high-gamma activity as an accurate biomarker of ictal recruitment in limbic structures. However, reduced neuronal firing suggested preserved inhibition in mesial temporal structures despite simultaneous indicators of seizure recruitment, in contrast to the inhibitory collapse scenario documented in neocortex. Further study is needed to determine if this activity is ubiquitous to hippocampal seizures or indicates a 'seizure-responsive' state in which the hippocampus is not the primary driver. If the latter, distinguishing such cases may help to refine the surgical treatment of mesial temporal lobe epilepsy.
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Affiliation(s)
- Alexander H Agopyan-Miu
- Department of Neurological Surgery, Columbia University Medical Center, NewYork, NY 10032, USA
| | - Edward M Merricks
- Department of Neurology, Columbia University Medical Center, NewYork, NY 10032, USA
| | - Elliot H Smith
- Department of Neurology, Columbia University Medical Center, NewYork, NY 10032, USA
- Department of Neurosurgery, University of Utah, Salt Lake City, UT 84132, USA
| | - Guy M McKhann
- Department of Neurological Surgery, Columbia University Medical Center, NewYork, NY 10032, USA
| | - Sameer A Sheth
- Department of Neurosurgery, Baylor College of Medicine, Houston TX 77030, USA
| | - Neil A Feldstein
- Department of Neurological Surgery, Columbia University Medical Center, NewYork, NY 10032, USA
| | - Andrew J Trevelyan
- Biosciences Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Catherine A Schevon
- Department of Neurology, Columbia University Medical Center, NewYork, NY 10032, USA
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3
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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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4
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Kundu B, Charlebois CM, Nesterovich Anderson D, Peters A, Rolston JD. Chronic intracranial recordings after resection for epilepsy reveal a "running down" of epileptiform activity. Epilepsia 2023; 64:e135-e142. [PMID: 37163225 PMCID: PMC10524582 DOI: 10.1111/epi.17645] [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: 06/13/2022] [Revised: 05/06/2023] [Accepted: 05/08/2023] [Indexed: 05/11/2023]
Abstract
We describe an electrical "running down" phenomenon and also a consistent spectral change (in the aperiodic component of the power spectrum) derived from chronic interictal electrocorticography (ECoG) after surgery in a patient with drug-resistant epilepsy. These data were recorded using a closed-loop neurostimulation system that was implanted after resection. The patient has been seizure-free for 2.5 years since resection without requiring the neurostimulator to be turned on to stimulate. Concurrently, there was an exponential decrease in the number of epileptiform electrographic detections recorded by the device, particularly over the first 26 weeks, indicative of an electrical running down phenomenon as the brain adapted to an extended period of seizure freedom. We also find that the aperiodic exponent of the power spectrum gradually decreases over time. The aperiodic component of intracranial ECoG may represent a novel marker of epileptogenicity, independent of seizures.
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Affiliation(s)
- Bornali Kundu
- Department of Neurosurgery, Clinical Neurosciences Center, University of Utah, Salt Lake City, Utah, USA
| | - Chantel M. Charlebois
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah, USA
- Scientific Computing & Imaging Institute, University of Utah, Salt Lake City, Utah, USA
| | - Daria Nesterovich Anderson
- Department of Neurosurgery, Clinical Neurosciences Center, University of Utah, Salt Lake City, Utah, USA
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, USA
| | - Angela Peters
- Department of Neurology, University of Utah, Salt Lake City, Utah, USA
| | - John D. Rolston
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah, USA
- Department of Neurosurgery, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, USA
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5
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Magloire V, Savtchenko LP, Jensen TP, Sylantyev S, Kopach O, Cole N, Tyurikova O, Kullmann DM, Walker MC, Marvin JS, Looger LL, Hasseman JP, Kolb I, Pavlov I, Rusakov DA. Volume-transmitted GABA waves pace epileptiform rhythms in the hippocampal network. Curr Biol 2023; 33:1249-1264.e7. [PMID: 36921605 PMCID: PMC10615848 DOI: 10.1016/j.cub.2023.02.051] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 01/05/2023] [Accepted: 02/15/2023] [Indexed: 03/17/2023]
Abstract
Mechanisms that entrain and pace rhythmic epileptiform discharges remain debated. Traditionally, the quest to understand them has focused on interneuronal networks driven by synaptic GABAergic connections. However, synchronized interneuronal discharges could also trigger the transient elevations of extracellular GABA across the tissue volume, thus raising tonic conductance (Gtonic) of synaptic and extrasynaptic GABA receptors in multiple cells. Here, we monitor extracellular GABA in hippocampal slices using patch-clamp GABA "sniffer" and a novel optical GABA sensor, showing that periodic epileptiform discharges are preceded by transient, region-wide waves of extracellular GABA. Neural network simulations that incorporate volume-transmitted GABA signals point to a cycle of GABA-driven network inhibition and disinhibition underpinning this relationship. We test and validate this hypothesis using simultaneous patch-clamp recordings from multiple neurons and selective optogenetic stimulation of fast-spiking interneurons. Critically, reducing GABA uptake in order to decelerate extracellular GABA fluctuations-without affecting synaptic GABAergic transmission or resting GABA levels-slows down rhythmic activity. Our findings thus unveil a key role of extrasynaptic, volume-transmitted GABA in pacing regenerative rhythmic activity in brain networks.
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Affiliation(s)
- Vincent Magloire
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK.
| | - Leonid P Savtchenko
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK.
| | - Thomas P Jensen
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
| | - Sergyi Sylantyev
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK; Rowett Institute, University of Aberdeen, Ashgrove Road West, Aberdeen AB25 2ZD, UK
| | - Olga Kopach
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
| | - Nicholas Cole
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
| | - Olga Tyurikova
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
| | - Dimitri M Kullmann
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
| | - Matthew C Walker
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
| | - Jonathan S Marvin
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Loren L Looger
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA; Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093, USA; GENIE Project Team, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Jeremy P Hasseman
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA; GENIE Project Team, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Ilya Kolb
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA; GENIE Project Team, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Ivan Pavlov
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
| | - Dmitri A Rusakov
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK.
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6
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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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Goode LK, Fusilier AR, Remiszewski N, Reeves JM, Abiraman K, Defenderfer M, Paul JR, McMahon LL, Gamble KL. Examination of Diurnal Variation and Sex Differences in Hippocampal Neurophysiology and Spatial Memory. eNeuro 2022; 9:ENEURO.0124-22.2022. [PMID: 36265903 PMCID: PMC9668349 DOI: 10.1523/eneuro.0124-22.2022] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 09/29/2022] [Accepted: 10/10/2022] [Indexed: 12/24/2022] Open
Abstract
Circadian rhythms are biological processes that cycle across 24 h and regulate many facets of neurophysiology, including learning and memory. Circadian variation in spatial memory task performance is well documented; however, the effect of sex across circadian time (CT) remains unclear. Additionally, little is known regarding the impact of time-of-day on hippocampal neuronal physiology. Here, we investigated the influence of both sex and time-of-day on hippocampal neurophysiology and memory in mice. Performance on the object location memory (OLM) task depended on both circadian time and sex, with memory enhanced at night in males but during the day in females. Long-term synaptic potentiation (LTP) magnitude at CA3-CA1 synapses was greater at night compared with day in both sexes. Next, we measured spontaneous synaptic excitation and inhibition onto CA1 pyramidal neurons. Frequency and amplitude of inhibition was greater during the day compared with night, regardless of sex. Frequency and amplitude of excitation was larger in females, compared with males, independent of time-of-day, although both time-of-day and sex influenced presynaptic release probability. At night, CA1 pyramidal neurons showed enhanced excitability (action potential firing and/or baseline potential) that was dependent on synaptic excitation and inhibition, regardless of sex. This study emphasizes the importance of sex and time-of-day in hippocampal physiology, especially given that many neurologic disorders impacting the hippocampus are linked to circadian disruption and present differently in men and women. Knowledge about how sex and circadian rhythms affect hippocampal physiology can improve the translational relevancy of therapeutics and inform the appropriate timing of existing treatments.
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Affiliation(s)
- Lacy K Goode
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham Heersink School of Medicine, Birmingham 35233, AL
| | - Allison R Fusilier
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham Heersink School of Medicine, Birmingham 35233, AL
| | - Natalie Remiszewski
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham Heersink School of Medicine, Birmingham 35233, AL
| | - Jacob M Reeves
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham Heersink School of Medicine, Birmingham 35233, AL
| | | | - Matthew Defenderfer
- Research Computing, Information Technology, University of Alabama at Birmingham, Birmingham 35233, AL
| | - Jodi R Paul
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham Heersink School of Medicine, Birmingham 35233, AL
| | - Lori L McMahon
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham 35233, AL
| | - Karen L Gamble
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham Heersink School of Medicine, Birmingham 35233, AL
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8
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Gill BJA, Khan FA, Goldberg AR, Merricks EM, Wu X, Sosunov AA, Sudhakar TD, Dovas A, Lado W, Michalak AJ, Teoh JJ, Liou JY, Frankel WN, McKhann GM, Canoll P, Schevon CA. Single unit analysis and wide-field imaging reveal alterations in excitatory and inhibitory neurons in glioma. Brain 2022; 145:3666-3680. [PMID: 35552612 PMCID: PMC10202150 DOI: 10.1093/brain/awac168] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 02/05/2022] [Accepted: 04/27/2022] [Indexed: 11/14/2022] Open
Abstract
While several studies have attributed the development of tumour-associated seizures to an excitatory-inhibitory imbalance, we have yet to resolve the spatiotemporal interplay between different types of neuron in glioma-infiltrated cortex. Herein, we combined methods for single unit analysis of microelectrode array recordings with wide-field optical mapping of Thy1-GCaMP pyramidal cells in an ex vivo acute slice model of diffusely infiltrating glioma. This enabled simultaneous tracking of individual neurons from both excitatory and inhibitory populations throughout seizure-like events. Moreover, our approach allowed for observation of how the crosstalk between these neurons varied spatially, as we recorded across an extended region of glioma-infiltrated cortex. In tumour-bearing slices, we observed marked alterations in single units classified as putative fast-spiking interneurons, including reduced firing, activity concentrated within excitatory bursts and deficits in local inhibition. These results were correlated with increases in overall excitability. Mechanistic perturbation of this system with the mTOR inhibitor AZD8055 revealed increased firing of putative fast-spiking interneurons and restoration of local inhibition, with concomitant decreases in overall excitability. Altogether, our findings suggest that diffusely infiltrating glioma affect the interplay between excitatory and inhibitory neuronal populations in a reversible manner, highlighting a prominent role for functional mechanisms linked to mTOR activation.
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Affiliation(s)
- Brian J A Gill
- Department of Neurological Surgery, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Farhan A Khan
- Department of Neurological Surgery, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Alexander R Goldberg
- Department of Pathology and Cell Biology, Irving Cancer Research Center, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Edward M Merricks
- Department of Neurology, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Xiaoping Wu
- Department of Neurological Surgery, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Alexander A Sosunov
- Department of Neurological Surgery, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Tejaswi D Sudhakar
- Department of Neurological Surgery, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Athanassios Dovas
- Department of Pathology and Cell Biology, Irving Cancer Research Center, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Wudu Lado
- Department of Neurology, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Andrew J Michalak
- Department of Neurology, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Jia Jie Teoh
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Jyun-you Liou
- Department of Anesthesiology, Weill Cornell Medicine, New York, NY 10065, USA
| | - Wayne N Frankel
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY 10032, USA
- Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Guy M McKhann
- Department of Neurological Surgery, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Peter Canoll
- Department of Pathology and Cell Biology, Irving Cancer Research Center, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Catherine A Schevon
- Department of Neurology, Columbia University Irving Medical Center, New York, NY 10032, USA
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9
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Proskurina EY, Zaitsev AV. Regulation of Potassium and Chloride Concentrations in Nervous Tissue as a Method of Anticonvulsant Therapy. J EVOL BIOCHEM PHYS+ 2022. [DOI: 10.1134/s0022093022050015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Abstract
Under some pathological conditions, such as pharmacoresistant
epilepsy, status epilepticus or certain forms of genetic abnormalities,
spiking activity of GABAergic interneurons may enhance excitation
processes in neuronal circuits and provoke the generation of ictal
discharges. As a result, anticonvulsants acting on the GABAergic
system may be ineffective or even increase seizure activity. This
paradoxical effect of the inhibitory system is due to ionic imbalances
in nervous tissue. This review addresses the mechanisms of ictal
discharge initiation in neuronal networks due to the imbalance of
chloride and potassium ions, as well as possible ways to regulate
ionic concentrations. Both the enhancement (or attenuation) of the
activity of certain neuronal ion transporters and ion pumps and
their additional expression via gene therapy can be effective in
suppressing seizure activity caused by ionic imbalances. The Na+–K+-pump,
NKCC1 and KCC2 cotransporters are important for maintaining proper
K+ and Cl– concentrations
in nervous tissue, having been repeatedly considered as pharmacological
targets for antiepileptic exposures. Further progress in this direction
is hampered by the lack of sufficiently selective pharmacological
tools and methods for providing effective drug delivery to the epileptic
focus. The use of the gene therapy techniques, such as overexpressing
of the KCC2 transporter in the epileptic focus, seems to be a more promising
approach. Another possible direction could be the use of optogenetic
tools, namely specially designed light-activated ion pumps or ion
channels. In this case, photon energy can be used to create the
required gradients of chloride and potassium ions, although these
methods also have significant limitations which complicate their
rapid introduction into medicine.
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10
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Gentiletti D, de Curtis M, Gnatkovsky V, Suffczynski P. Focal seizures are organized by feedback between neural activity and ion concentration changes. eLife 2022; 11:68541. [PMID: 35916367 PMCID: PMC9377802 DOI: 10.7554/elife.68541] [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: 03/18/2021] [Accepted: 07/12/2022] [Indexed: 11/13/2022] Open
Abstract
Human and animal EEG data demonstrate that focal seizures start with low-voltage fast activity, evolve into rhythmic burst discharges and are followed by a period of suppressed background activity. This suggests that processes with dynamics in the range of tens of seconds govern focal seizure evolution. We investigate the processes associated with seizure dynamics by complementing the Hodgkin-Huxley mathematical model with the physical laws that dictate ion movement and maintain ionic gradients. Our biophysically realistic computational model closely replicates the electrographic pattern of a typical human focal seizure characterized by low voltage fast activity onset, tonic phase, clonic phase and postictal suppression. Our study demonstrates, for the first time in silico, the potential mechanism of seizure initiation by inhibitory interneurons via the initial build-up of extracellular K+ due to intense interneuronal spiking. The model also identifies ionic mechanisms that may underlie a key feature in seizure dynamics, i.e., progressive slowing down of ictal discharges towards the end of seizure. Our model prediction of specific scaling of inter-burst intervals is confirmed by seizure data recorded in the whole guinea pig brain in vitro and in humans, suggesting that the observed termination pattern may hold across different species. Our results emphasize ionic dynamics as elementary processes behind seizure generation and indicate targets for new therapeutic strategies.
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11
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Hesse J, Schleimer JH, Maier N, Schmitz D, Schreiber S. Temperature elevations can induce switches to homoclinic action potentials that alter neural encoding and synchronization. Nat Commun 2022; 13:3934. [PMID: 35803913 PMCID: PMC9270341 DOI: 10.1038/s41467-022-31195-6] [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: 09/30/2020] [Accepted: 06/07/2022] [Indexed: 11/09/2022] Open
Abstract
Almost seventy years after the discovery of the mechanisms of action potential generation, some aspects of their computational consequences are still not fully understood. Based on mathematical modeling, we here explore a type of action potential dynamics – arising from a saddle-node homoclinic orbit bifurcation - that so far has received little attention. We show that this type of dynamics is to be expected by specific changes in common physiological parameters, like an elevation of temperature. Moreover, we demonstrate that it favours synchronization patterns in networks – a feature that becomes particularly prominent when system parameters change such that homoclinic spiking is induced. Supported by in-vitro hallmarks for homoclinic spikes in the rodent brain, we hypothesize that the prevalence of homoclinic spikes in the brain may be underestimated and provide a missing link between the impact of biophysical parameters on abrupt transitions between asynchronous and synchronous states of electrical activity in the brain. The intrinsic dynamics of neurons, in particular the generation action potentials, can impact neural network states and processes of encoding information. The authors demonstrate how the elevation of temperature induces a type of action potential dynamics that favors synchronization patterns in neural networks.
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Affiliation(s)
- Janina Hesse
- Institute for Theoretical Biology, Humboldt-Universität zu Berlin, Berlin, Germany.,Bernstein Center for Computational Neuroscience, Berlin, Germany.,Institute for Systems Medicine, Department of Human Medicine, MSH Medical School Hamburg-University of Applied Sciences and Medical University, Hamburg, 20457, Germany.,Charité-Universitätsmedizin Berlin, Corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Jan-Hendrik Schleimer
- Institute for Theoretical Biology, Humboldt-Universität zu Berlin, Berlin, Germany.,Bernstein Center for Computational Neuroscience, Berlin, Germany
| | - Nikolaus Maier
- Neuroscience Research Center - Charité-Universitätsmedizin Berlin, Corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, German Center for Neurodegenerative Diseases (DZNE) Berlin, Berlin, 10117, Germany.,Max-Delbrück-Centrum (MDC) for Molecular Medicine, Berlin, 13125, Germany
| | - Dietmar Schmitz
- Bernstein Center for Computational Neuroscience, Berlin, Germany.,Neuroscience Research Center - Charité-Universitätsmedizin Berlin, Corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, German Center for Neurodegenerative Diseases (DZNE) Berlin, Berlin, 10117, Germany.,Max-Delbrück-Centrum (MDC) for Molecular Medicine, Berlin, 13125, Germany
| | - Susanne Schreiber
- Institute for Theoretical Biology, Humboldt-Universität zu Berlin, Berlin, Germany. .,Bernstein Center for Computational Neuroscience, Berlin, Germany.
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12
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Tipton AE, Russek SJ. Regulation of Inhibitory Signaling at the Receptor and Cellular Level; Advances in Our Understanding of GABAergic Neurotransmission and the Mechanisms by Which It Is Disrupted in Epilepsy. Front Synaptic Neurosci 2022; 14:914374. [PMID: 35874848 PMCID: PMC9302637 DOI: 10.3389/fnsyn.2022.914374] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 05/17/2022] [Indexed: 11/13/2022] Open
Abstract
Inhibitory signaling in the brain organizes the neural circuits that orchestrate how living creatures interact with the world around them and how they build representations of objects and ideas. Without tight control at multiple points of cellular engagement, the brain’s inhibitory systems would run down and the ability to extract meaningful information from excitatory events would be lost leaving behind a system vulnerable to seizures and to cognitive decline. In this review, we will cover many of the salient features that have emerged regarding the dynamic regulation of inhibitory signaling seen through the lens of cell biology with an emphasis on the major building blocks, the ligand-gated ion channel receptors that are the first transduction point when the neurotransmitter GABA is released into the synapse. Epilepsy association will be used to indicate importance of key proteins and their pathways to brain function and to introduce novel areas for therapeutic intervention.
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Affiliation(s)
- Allison E. Tipton
- Graduate Program for Neuroscience, Boston University, Boston, MA, United States
- Biomolecular Pharmacology Program, Boston University School of Medicine, Boston, MA, United States
- Boston University MD/PhD Training Program, Boston, MA, United States
| | - Shelley J. Russek
- Biomolecular Pharmacology Program, Boston University School of Medicine, Boston, MA, United States
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA, United States
- Center for Systems Neuroscience, Boston University, Boston, MA, United States
- Boston University MD/PhD Training Program, Boston, MA, United States
- *Correspondence: Shelley J. Russek,
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13
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Multimodal, Multiscale Insights into Hippocampal Seizures Enabled by Transparent, Graphene-Based Microelectrode Arrays. eNeuro 2022; 9:ENEURO.0386-21.2022. [PMID: 35470227 PMCID: PMC9087744 DOI: 10.1523/eneuro.0386-21.2022] [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: 09/21/2021] [Revised: 04/14/2022] [Accepted: 04/15/2022] [Indexed: 11/21/2022] Open
Abstract
Hippocampal seizures are a defining feature of mesial temporal lobe epilepsy (MTLE). Area CA1 of the hippocampus is commonly implicated in the generation of seizures, which may occur because of the activity of endogenous cell populations or of inputs from other regions within the hippocampal formation. Simultaneously observing activity at the cellular and network scales in vivo remains challenging. Here, we present a novel technology for simultaneous electrophysiology and multicellular calcium imaging of CA1 pyramidal cells (PCs) in mice enabled by a transparent graphene-based microelectrode array (Gr MEA). We examine PC firing at seizure onset, oscillatory coupling, and the dynamics of the seizure traveling wave as seizures evolve. Finally, we couple features derived from both modalities to predict the speed of the traveling wave using bootstrap aggregated regression trees. Analysis of the most important features in the regression trees suggests a transition among states in the evolution of hippocampal seizures.
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14
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Lau LA, Staley KJ, Lillis KP. In vitro ictogenesis is stochastic at the single neuron level. Brain 2022; 145:531-541. [PMID: 34431994 PMCID: PMC9014754 DOI: 10.1093/brain/awab312] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 07/13/2021] [Accepted: 07/30/2021] [Indexed: 11/14/2022] Open
Abstract
Seizure initiation is the least understood and most disabling element of epilepsy. Studies of ictogenesis require high speed recordings at cellular resolution in the area of seizure onset. However, in vivo seizure onset areas cannot be determined at the level of resolution necessary to enable such studies. To circumvent these challenges, we used novel GCaMP7-based calcium imaging in the organotypic hippocampal slice culture model of post-traumatic epilepsy in mice. Organotypic hippocampal slice cultures generate spontaneous, recurrent seizures in a preparation in which it is feasible to image the activity of the entire network (with no unseen inputs existing). Chronic calcium imaging of the entire hippocampal network, with paired electrophysiology, revealed three patterns of seizure onset: (i) low amplitude fast activity; (ii) sentinel spike; and (iii) spike burst and low amplitude fast activity onset. These patterns recapitulate common features of human seizure onset, including low voltage fast activity and spike discharges. Weeks-long imaging of seizure activity showed a characteristic evolution in onset type and a refinement of the seizure onset zone. Longitudinal tracking of individual neurons revealed that seizure onset is stochastic at the single neuron level, suggesting that seizure initiation activates neurons in non-stereotyped sequences seizure to seizure. This study demonstrates for the first time that transitions to seizure are not initiated by a small number of neuronal 'bad actors' (such as overly connected hub cells), but rather by network changes which enable the onset of pathology among large populations of neurons.
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Affiliation(s)
- Lauren A Lau
- Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA.,Harvard Medical School, Boston, MA 02115, USA
| | - Kevin J Staley
- Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA.,Harvard Medical School, Boston, MA 02115, USA
| | - Kyle P Lillis
- Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA.,Harvard Medical School, Boston, MA 02115, USA
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15
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Niemeyer JE, Gadamsetty P, Chun C, Sylvester S, Lucas JP, Ma H, Schwartz TH, Aksay ERF. Seizures initiate in zones of relative hyperexcitation in a zebrafish epilepsy model. Brain 2022; 145:2347-2360. [PMID: 35196385 DOI: 10.1093/brain/awac073] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 02/03/2022] [Accepted: 02/05/2022] [Indexed: 11/12/2022] Open
Abstract
Seizures are thought to arise from an imbalance of excitatory and inhibitory neuronal activity. While most classical studies suggest excessive excitatory neural activity plays a generative role, some recent findings challenge this view and instead argue that excessive activity in inhibitory neurons initiates seizures. We investigated this question of imbalance in a zebrafish seizure model with two-photon imaging of excitatory and inhibitory neuronal activity throughout the brain using a nuclear-localized calcium sensor. We found that seizures consistently initiated in circumscribed zones of the midbrain before propagating to other brain regions. Excitatory neurons were both more prevalent and more likely to be recruited than inhibitory neurons in initiation as compared with propagation zones. These findings support a mechanistic picture whereby seizures initiate in a region of hyper-excitation, then propagate more broadly once inhibitory restraint in the surround is overcome.
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Affiliation(s)
- James E Niemeyer
- Department of Neurological Surgery, Weill Cornell Medicine, New York, NY 10065, USA.,Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA
| | - Poornima Gadamsetty
- Department of Neurological Surgery, Weill Cornell Medicine, New York, NY 10065, USA
| | - Chanwoo Chun
- Institute for Computational Biomedicine and the Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY 10065, USA
| | - Sherika Sylvester
- Institute for Computational Biomedicine and the Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY 10065, USA
| | - Jacob P Lucas
- Department of Neurological Surgery, Weill Cornell Medicine, New York, NY 10065, USA
| | - Hongtao Ma
- Department of Neurological Surgery, Weill Cornell Medicine, New York, NY 10065, USA.,Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA
| | - Theodore H Schwartz
- Department of Neurological Surgery, Weill Cornell Medicine, New York, NY 10065, USA.,Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA
| | - Emre R F Aksay
- Institute for Computational Biomedicine and the Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY 10065, USA
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16
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Godoy LD, Prizon T, Rossignoli MT, Leite JP, Liberato JL. Parvalbumin Role in Epilepsy and Psychiatric Comorbidities: From Mechanism to Intervention. Front Integr Neurosci 2022; 16:765324. [PMID: 35250498 PMCID: PMC8891758 DOI: 10.3389/fnint.2022.765324] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 01/24/2022] [Indexed: 12/22/2022] Open
Abstract
Parvalbumin is a calcium-binding protein present in inhibitory interneurons that play an essential role in regulating many physiological processes, such as intracellular signaling and synaptic transmission. Changes in parvalbumin expression are deeply related to epilepsy, which is considered one of the most disabling neuropathologies. Epilepsy is a complex multi-factor group of disorders characterized by periods of hypersynchronous activity and hyperexcitability within brain networks. In this scenario, inhibitory neurotransmission dysfunction in modulating excitatory transmission related to the loss of subsets of parvalbumin-expressing inhibitory interneuron may have a prominent role in disrupted excitability. Some studies also reported that parvalbumin-positive interneurons altered function might contribute to psychiatric comorbidities associated with epilepsy, such as depression, anxiety, and psychosis. Understanding the epileptogenic process and comorbidities associated with epilepsy have significantly advanced through preclinical and clinical investigation. In this review, evidence from parvalbumin altered function in epilepsy and associated psychiatric comorbidities were explored with a translational perspective. Some advances in potential therapeutic interventions are highlighted, from current antiepileptic and neuroprotective drugs to cutting edge modulation of parvalbumin subpopulations using optogenetics, designer receptors exclusively activated by designer drugs (DREADD) techniques, transcranial magnetic stimulation, genome engineering, and cell grafting. Creating new perspectives on mechanisms and therapeutic strategies is valuable for understanding the pathophysiology of epilepsy and its psychiatric comorbidities and improving efficiency in clinical intervention.
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Affiliation(s)
- Lívea Dornela Godoy
- Department of Psychology, Faculty of Philosophy, Sciences and Letters of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil
| | - Tamiris Prizon
- Department of Neuroscience and Behavioral Sciences, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - Matheus Teixeira Rossignoli
- Department of Neuroscience and Behavioral Sciences, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - João Pereira Leite
- Department of Neuroscience and Behavioral Sciences, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
- João Pereira Leite,
| | - José Luiz Liberato
- Department of Neuroscience and Behavioral Sciences, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
- *Correspondence: José Luiz Liberato,
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17
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Cheah CS, Beckman MA, Catterall WA, Oakley JC. Sharp-Wave Ripple Frequency and Interictal Epileptic Discharges Increase in Tandem During Thermal Induction of Seizures in a Mouse Model of Genetic Epilepsy. Front Cell Neurosci 2021; 15:751762. [PMID: 34733140 PMCID: PMC8558377 DOI: 10.3389/fncel.2021.751762] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 09/28/2021] [Indexed: 11/13/2022] Open
Abstract
Dravet Syndrome (DS) is a genetic, infantile-onset epilepsy with refractory seizures and severe cognitive impairment. While network level pathophysiology is poorly understood, work in genetic mouse models of DS reveals selective reduction of inhibitory interneuron excitability, a likely mechanism of seizures and comorbidities. Consistent with the critical role of interneurons in timing and recruitment of network activity, hippocampal sharp wave ripples (SPW-R)—interneuron dependent compound brain rhythms essential for spatial learning and memory—are less frequent and ripple frequency is slower in DS mice, both likely to impair cognitive performance. Febrile seizures are characteristic of DS, reflecting a temperature-dependent shift in excitation–inhibition balance. DS interneurons are sensitive to depolarization block and may fall silent with increased excitation precipitating epileptic transformation of ripples. To determine the temperature dependence of SWP-R features and relationship of SPW-R to hippocampal interictal activity, we recorded hippocampal local field potentials in a DS mouse model and wildtype littermate controls while increasing core body temperature. In both genotypes, temperature elevation speeds ripple frequency, although DS ripples remain consistently slower. The rate of SPW-R also increases in both genotypes but subsequently falls in DS mice as interictal epileptic activity simultaneously increases preceding a thermally-evoked seizure. Epileptic events occur intermixed with SPW-R, some during SPW-R burst complexes, and transiently suppress SPW-R occurrence suggesting shared network elements. Together these data demonstrate a temperature dependence of SPW-R rate and ripple frequency and suggest a pathophysiologic mechanism by which elevated temperature transforms a normal brain rhythm into epileptic event.
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Affiliation(s)
- Christine S Cheah
- Department of Neurology, University of Washington, Seattle, WA, United States
| | - Megan A Beckman
- Department of Pharmacology, University of Washington, Seattle, WA, United States
| | - William A Catterall
- Department of Pharmacology, University of Washington, Seattle, WA, United States
| | - John C Oakley
- Department of Neurology, University of Washington, Seattle, WA, United States.,Department of Pharmacology, University of Washington, Seattle, WA, United States
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18
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Dudok B, Klein PM, Soltesz I. Toward Understanding the Diverse Roles of Perisomatic Interneurons in Epilepsy. Epilepsy Curr 2021; 22:54-60. [PMID: 35233202 PMCID: PMC8832350 DOI: 10.1177/15357597211053687] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Epileptic seizures are associated with excessive neuronal spiking. Perisomatic
γ-aminobutyric acid (GABA)ergic interneurons specifically innervate the subcellular
domains of postsynaptic excitatory cells that are critical for spike generation. With a
revolution in transcriptomics-based cell taxonomy driving the development of novel
transgenic mouse lines, selectively monitoring and modulating previously elusive
interneuron types is becoming increasingly feasible. Emerging evidence suggests that the
three types of hippocampal perisomatic interneurons, axo-axonic cells, along with
parvalbumin- and cholecystokinin-expressing basket cells, each follow unique activity
patterns in vivo, suggesting distinctive roles in regulating epileptic networks.
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Affiliation(s)
- Barna Dudok
- Department of Neurosurgery, Stanford University, Stanford, CA, USA
| | - Peter M. Klein
- Department of Neurosurgery, Stanford University, Stanford, CA, USA
| | - Ivan Soltesz
- Department of Neurosurgery, Stanford University, Stanford, CA, USA
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19
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An inventory of basic research in temporal lobe epilepsy. Rev Neurol (Paris) 2021; 177:1069-1081. [PMID: 34176659 DOI: 10.1016/j.neurol.2021.02.390] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 01/26/2021] [Accepted: 02/05/2021] [Indexed: 12/25/2022]
Abstract
Temporal lobe epilepsy is a severe neurological disease, characterized by seizure occurrence and invalidating cognitive co-morbidities, which affects up to 1% of the adults. Roughly one third of the patients are resistant to any conventional pharmacological treatments. The last option in that case is the surgical removal of the epileptic focus, with no guarantee for clinical symptom alleviation. This state of affairs requests the identification of cellular or molecular targets for novel therapeutic approaches with limited side effects. Here we review some generalities about the disease as well as some of the most recent discoveries about the cellular and molecular mechanisms of TLE, and the latest perspectives for novel treatments.
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20
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In Vivo Microelectrode Arrays for Detecting Multi-Region Epileptic Activities in the Hippocampus in the Latent Period of Rat Model of Temporal Lobe Epilepsy. MICROMACHINES 2021; 12:mi12060659. [PMID: 34205055 PMCID: PMC8228658 DOI: 10.3390/mi12060659] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Revised: 05/26/2021] [Accepted: 05/30/2021] [Indexed: 11/25/2022]
Abstract
Temporal lobe epilepsy (TLE) is a form of refractory focal epilepsy, which includes a latent period and a chronic period. Microelectrode arrays capable of multi-region detection of neural activities are important for accurately identifying the epileptic focus and pathogenesis mechanism in the latent period of TLE. Here, we fabricated multi-shank MEAs to detect neural activities in the DG, hilus, CA3, and CA1 in the TLE rat model. In the latent period in TLE rats, seizures were induced and changes in neural activities were detected. The results showed that induced seizures spread from the hilus and CA3 to other areas. Furthermore, interneurons in the hilus and CA3 were more excited than principal cells and exhibited rhythmic oscillations at approximately 15 Hz in grand mal seizures. In addition, the power spectral density (PSD) of neural spikes and local field potentials (LFPs) were synchronized in the frequency domain of the alpha band (9–15 Hz) after the induction of seizures. The results suggest that fabricated MEAs have the advantages of simultaneous and precise detection of neural activities in multiple subregions of the hippocampus. Our MEAs promote the study of cellular mechanisms of TLE during the latent period, which provides an important basis for the diagnosis of the lesion focus of TLE.
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21
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Lim HK, You N, Bae S, Kang BM, Shon YM, Kim SG, Suh M. Differential contribution of excitatory and inhibitory neurons in shaping neurovascular coupling in different epileptic neural states. J Cereb Blood Flow Metab 2021; 41:1145-1161. [PMID: 32669018 PMCID: PMC8054729 DOI: 10.1177/0271678x20934071] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Understanding the neurovascular coupling (NVC) underlying hemodynamic changes in epilepsy is crucial to properly interpreting functional brain imaging signals associated with epileptic events. However, how excitatory and inhibitory neurons affect vascular responses in different epileptic states remains unknown. We conducted real-time in vivo measurements of cerebral blood flow (CBF), vessel diameter, and excitatory and inhibitory neuronal calcium signals during recurrent focal seizures. During preictal states, decreases in CBF and arteriole diameter were closely related to decreased γ-band local field potential (LFP) power, which was linked to relatively elevated excitatory and reduced inhibitory neuronal activity levels. Notably, this preictal condition was followed by a strengthened ictal event. In particular, the preictal inhibitory activity level was positively correlated with coherent oscillating activity specific to inhibitory neurons. In contrast, ictal states were characterized by elevated synchrony in excitatory neurons. Given these findings, we suggest that excitatory and inhibitory neurons differentially contribute to shaping the ictal and preictal neural states, respectively. Moreover, the preictal vascular activity, alongside with the γ-band, may reflect the relative levels of excitatory and inhibitory neuronal activity, and upcoming ictal activity. Our findings provide useful insights into how perfusion signals of different epileptic states are related in terms of NVC.
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Affiliation(s)
- Hyun-Kyoung Lim
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, South Korea.,Department of Biological Sciences, Sungkyunkwan University, Suwon, South Korea
| | - Nayeon You
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, South Korea.,Department of Biomedical Engineering, Sungkyunkwan University, Suwon, South Korea
| | - Sungjun Bae
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, South Korea.,Department of Biomedical Engineering, Sungkyunkwan University, Suwon, South Korea
| | - Bok-Man Kang
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, South Korea.,Department of Biomedical Engineering, Sungkyunkwan University, Suwon, South Korea
| | - Young-Min Shon
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | - Seong-Gi Kim
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, South Korea.,Department of Biomedical Engineering, Sungkyunkwan University, Suwon, South Korea
| | - Minah Suh
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, South Korea.,Department of Biomedical Engineering, Sungkyunkwan University, Suwon, South Korea.,Biomedical Institute for Convergence at SKKU (BICS), Sungkyunkwan University, Suwon, South Korea.,Samsung Advanced Institute for Health Sciences & Technology (SAIHST), Sungkyunkwan University, Suwon, South Korea
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22
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Sparks FT, Liao Z, Li W, Grosmark A, Soltesz I, Losonczy A. Hippocampal adult-born granule cells drive network activity in a mouse model of chronic temporal lobe epilepsy. Nat Commun 2020; 11:6138. [PMID: 33262339 PMCID: PMC7708476 DOI: 10.1038/s41467-020-19969-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Accepted: 11/10/2020] [Indexed: 02/06/2023] Open
Abstract
Temporal lobe epilepsy (TLE) is characterized by recurrent seizures driven by synchronous neuronal activity. The reorganization of the dentate gyrus (DG) in TLE may create pathological conduction pathways for synchronous discharges in the temporal lobe, though critical microcircuit-level detail is missing from this pathophysiological intuition. In particular, the relative contribution of adult-born (abGC) and mature (mGC) granule cells to epileptiform network events remains unknown. We assess dynamics of abGCs and mGCs during interictal epileptiform discharges (IEDs) in mice with TLE as well as sharp-wave ripples (SPW-Rs) in healthy mice, and find that abGCs and mGCs are desynchronized and differentially recruited by IEDs compared to SPW-Rs. We introduce a neural topic model to explain these observations, and find that epileptic DG networks organize into disjoint, cell-type specific pathological ensembles in which abGCs play an outsized role. Our results characterize identified GC subpopulation dynamics in TLE, and reveal a specific contribution of abGCs to IEDs.
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Affiliation(s)
- F T Sparks
- Department of Neuroscience, Columbia University, New York, NY, USA
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
- The Kavli Institute for Brain Science, Columbia University, New York, NY, USA
| | - Z Liao
- Department of Neuroscience, Columbia University, New York, NY, USA
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
- The Kavli Institute for Brain Science, Columbia University, New York, NY, USA
| | - W Li
- Department of Neuroscience, Columbia University, New York, NY, USA
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
- The Kavli Institute for Brain Science, Columbia University, New York, NY, USA
| | - A Grosmark
- Department of Neuroscience, Columbia University, New York, NY, USA
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
- The Kavli Institute for Brain Science, Columbia University, New York, NY, USA
| | - I Soltesz
- Department of Neurosurgery, Stanford University, Stanford, CA, USA
| | - A Losonczy
- Department of Neuroscience, Columbia University, New York, NY, USA.
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA.
- The Kavli Institute for Brain Science, Columbia University, New York, NY, USA.
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23
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Almog Y, Fadila S, Brusel M, Mavashov A, Anderson K, Rubinstein M. Developmental alterations in firing properties of hippocampal CA1 inhibitory and excitatory neurons in a mouse model of Dravet syndrome. Neurobiol Dis 2020; 148:105209. [PMID: 33271326 DOI: 10.1016/j.nbd.2020.105209] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Revised: 11/07/2020] [Accepted: 11/24/2020] [Indexed: 11/17/2022] Open
Abstract
Dravet syndrome (Dravet) is a rare, severe childhood-onset epilepsy, caused by heterozygous de novo mutations in the SCN1A gene, encoding for the alpha subunit of the voltage-gated sodium channel, NaV1.1. The neuronal basis of Dravet is debated, with evidence favoring reduced function of inhibitory neurons, that might be transient, or enhanced activity of excitatory cells. Here, we utilized Dravet mice to trace developmental changes in the hippocampal CA1 circuit, examining the properties of CA1 horizontal stratum-oriens (SO) interneurons and pyramidal neurons, through the pre-epileptic, severe and stabilization stages of Dravet. Our data indicate that reduced function of SO interneurons persists from the pre-epileptic through the stabilization stages, with the greatest functional impairment observed during the severe stage. In contrast, opposing changes were detected in CA1 excitatory neurons, with a transient increase in their excitability during the pre-epileptic stage, followed by reduced excitability at the severe stage. Interestingly, alterations in the function of both inhibitory and excitatory neurons were more pronounced when the firing was evoked by synaptic stimulation, implying that loss of function of NaV1.1 may also affect somatodendritic functions. These results suggest a complex pathophysiological mechanism and indicate that the developmental trajectory of this disease is governed by reciprocal functional changes in both excitatory and inhibitory neurons.
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Affiliation(s)
- Yael Almog
- Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel; The Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Saja Fadila
- Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel; The Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Marina Brusel
- Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Anat Mavashov
- Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel; Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Karen Anderson
- Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Moran Rubinstein
- Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel; The Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel; Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel.
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24
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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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25
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Smith EH, Merricks EM, Liou JY, Casadei C, Melloni L, Thesen T, Friedman DJ, Doyle WK, Emerson RG, Goodman RR, McKhann GM, Sheth SA, Rolston JD, Schevon CA. Dual mechanisms of ictal high frequency oscillations in human rhythmic onset seizures. Sci Rep 2020; 10:19166. [PMID: 33154490 PMCID: PMC7645614 DOI: 10.1038/s41598-020-76138-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 10/23/2020] [Indexed: 11/24/2022] Open
Abstract
High frequency oscillations (HFOs) are bursts of neural activity in the range of 80 Hz or higher, recorded from intracranial electrodes during epileptiform discharges. HFOs are a proposed biomarker of epileptic brain tissue and may also be useful for seizure forecasting. Despite such clinical utility of HFOs, the spatial context and neuronal activity underlying these local field potential (LFP) events remains unclear. We sought to further understand the neuronal correlates of ictal high frequency LFPs using multielectrode array recordings in the human neocortex and mesial temporal lobe during rhythmic onset seizures. These multiscale recordings capture single cell, multiunit, and LFP activity from the human brain. We compare features of multiunit firing and high frequency LFP from microelectrodes and macroelectrodes during ictal discharges in both the seizure core and penumbra (spatial seizure domains defined by multiunit activity patterns). We report differences in spectral features, unit-local field potential coupling, and information theoretic characteristics of high frequency LFP before and after local seizure invasion. Furthermore, we tie these time-domain differences to spatial domains of seizures, showing that penumbral discharges are more broadly distributed and less useful for seizure localization. These results describe the neuronal and synaptic correlates of two types of pathological HFOs in humans and have important implications for clinical interpretation of rhythmic onset seizures.
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Affiliation(s)
- Elliot H Smith
- Department of Neurosurgery, University of Utah, Salt Lake City, 84132, USA.
- Department of Neurology, Columbia University, New York, 10032, USA.
| | | | - Jyun-You Liou
- Department of Anesthesiology, Cornell University, New York, 10065, USA
| | - Camilla Casadei
- Department of Neurology, Columbia University, New York, 10032, USA
| | - Lucia Melloni
- Department of Neurology, New York University, New York, 10016, USA
| | - Thomas Thesen
- Department of Neurology, New York University, New York, 10016, USA
- Department of Biomedical Sciences, University of Houston, Houston, 77004, USA
| | | | - Werner K Doyle
- Department of Neurological Surgery, New York University, New York, 10016, USA
| | | | | | - Guy M McKhann
- Department of Neurological Surgery, Columbia University, New York, 10032, USA
| | - Sameer A Sheth
- Department of Neurological Surgery, Baylor College of Medicine, Houston, 77030, USA
| | - John D Rolston
- Department of Neurosurgery, University of Utah, Salt Lake City, 84132, USA
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26
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Dudek FE. Loss of GABAergic Interneurons in Seizure-Induced Epileptogenesis-Two Decades Later and in a More Complex World. Epilepsy Curr 2020; 20:70S-72S. [PMID: 33059465 PMCID: PMC7726724 DOI: 10.1177/1535759720960464] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- F Edward Dudek
- Department of Neurosurgery 14434University of Utah School of Medicine, USA
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27
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Neurostimulation stabilizes spiking neural networks by disrupting seizure-like oscillatory transitions. Sci Rep 2020; 10:15408. [PMID: 32958802 PMCID: PMC7506027 DOI: 10.1038/s41598-020-72335-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 08/26/2020] [Indexed: 12/29/2022] Open
Abstract
An improved understanding of the mechanisms underlying neuromodulatory approaches to mitigate seizure onset is needed to identify clinical targets for the treatment of epilepsy. Using a Wilson–Cowan-motivated network of inhibitory and excitatory populations, we examined the role played by intrinsic and extrinsic stimuli on the network’s predisposition to sudden transitions into oscillatory dynamics, similar to the transition to the seizure state. Our joint computational and mathematical analyses revealed that such stimuli, be they noisy or periodic in nature, exert a stabilizing influence on network responses, disrupting the development of such oscillations. Based on a combination of numerical simulations and mean-field analyses, our results suggest that high variance and/or high frequency stimulation waveforms can prevent multi-stability, a mathematical harbinger of sudden changes in network dynamics. By tuning the neurons’ responses to input, stimuli stabilize network dynamics away from these transitions. Furthermore, our research shows that such stabilization of neural activity occurs through a selective recruitment of inhibitory cells, providing a theoretical undergird for the known key role these cells play in both the healthy and diseased brain. Taken together, these findings provide new vistas on neuromodulatory approaches to stabilize neural microcircuit activity.
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28
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Bartholome O, de la Brassinne Bonardeaux O, Neirinckx V, Rogister B. A Composite Sketch of Fast-Spiking Parvalbumin-Positive Neurons. Cereb Cortex Commun 2020; 1:tgaa026. [PMID: 34296100 PMCID: PMC8153048 DOI: 10.1093/texcom/tgaa026] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 06/15/2020] [Accepted: 06/15/2020] [Indexed: 01/28/2023] Open
Abstract
Parvalbumin-positive neurons are inhibitory neurons that release GABA and are mostly represented by fast-spiking basket or chandelier cells. They constitute a minor neuronal population, yet their peculiar profiles allow them to react quickly to any event in the brain under normal or pathological conditions. In this review, we will summarize the current knowledge about the fundamentals of fast-spiking parvalbumin-positive neurons, focusing on their morphology and specific channel/protein content. Next, we will explore their development, maturation, and migration in the brain. Finally, we will unravel their potential contribution to the physiopathology of epilepsy.
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Affiliation(s)
| | | | | | - Bernard Rogister
- GIGA-Neurosciences, University of Liege, 4000 Liège, Belgium.,Neurology Department, CHU, Academic Hospital, University of Liege, 4000 Liège, Belgium
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29
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Mossner JM, Batista-Brito R, Pant R, Cardin JA. Developmental loss of MeCP2 from VIP interneurons impairs cortical function and behavior. eLife 2020; 9:55639. [PMID: 32343226 PMCID: PMC7213975 DOI: 10.7554/elife.55639] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 04/28/2020] [Indexed: 12/24/2022] Open
Abstract
Rett Syndrome is a devastating neurodevelopmental disorder resulting from mutations in the gene MECP2. Mutations of Mecp2 that are restricted to GABAergic cell types largely replicate the behavioral phenotypes associated with mouse models of Rett Syndrome, suggesting a pathophysiological role for inhibitory interneurons. Recent work has suggested that vasoactive intestinal peptide-expressing (VIP) interneurons may play a critical role in the proper development and function of cortical circuits, making them a potential key point of vulnerability in neurodevelopmental disorders. However, little is known about the role of VIP interneurons in Rett Syndrome. Here we find that loss of MeCP2 specifically from VIP interneurons replicates key neural and behavioral phenotypes observed following global Mecp2 loss of function.
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Affiliation(s)
- James M Mossner
- Department of Neuroscience, Yale University, New Haven, United States
| | - Renata Batista-Brito
- Department of Neuroscience, Yale University, New Haven, United States.,Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, United States
| | - Rima Pant
- Department of Neuroscience, Yale University, New Haven, United States
| | - Jessica A Cardin
- Department of Neuroscience, Yale University, New Haven, United States.,Kavli Institute for Neuroscience, Yale University, New Haven, United States
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30
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Amakhin DV, Smolensky IV, Soboleva EB, Zaitsev AV. Paradoxical Anticonvulsant Effect of Cefepime in the Pentylenetetrazole Model of Seizures in Rats. Pharmaceuticals (Basel) 2020; 13:ph13050080. [PMID: 32357511 PMCID: PMC7281561 DOI: 10.3390/ph13050080] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 04/22/2020] [Accepted: 04/24/2020] [Indexed: 01/03/2023] Open
Abstract
Many β-lactam antibiotics, including cephalosporins, may cause neurotoxic and proconvulsant effects. The main molecular mechanism of such effects is considered to be γ-aminobutyric acid type a (GABAa) receptor blockade, leading to the suppression of GABAergic inhibition and subsequent overexcitation. We found that cefepime (CFP), a cephalosporin, has a pronounced antiepileptic effect in the pentylenetetrazole (PTZ)-induced seizure model by decreasing the duration and severity of the seizure and animal mortality. This effect was specific to the PTZ model. In line with findings of previous studies, CFP exhibited a proconvulsant effect in other models, including the maximal electroshock model and 4-aminopyridine model of epileptiform activity, in vitro. To determine the antiepileptic mechanism of CFP in the PTZ model, we used whole-cell patch-clamp recordings. We demonstrated that CFP or PTZ decreased the amplitude of GABAa receptor-mediated postsynaptic currents. PTZ also decreased the current decay time constant and temporal summation of synaptic responses. In contrast, CFP slightly increased the decay time constant and did not affect summation. When applied together, CFP prevented alterations to the summation of responses by PTZ, strongly reducing the effects of PTZ on repetitive inhibitory synaptic transmission. The latter may explain the antiepileptic effect of CFP in the PTZ model.
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31
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Interneuron Desynchronization Precedes Seizures in a Mouse Model of Dravet Syndrome. J Neurosci 2020; 40:2764-2775. [PMID: 32102923 DOI: 10.1523/jneurosci.2370-19.2020] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 12/27/2019] [Accepted: 02/13/2020] [Indexed: 12/14/2022] Open
Abstract
Recurrent seizures, which define epilepsy, are transient abnormalities in the electrical activity of the brain. The mechanistic basis of seizure initiation, and the contribution of defined neuronal subtypes to seizure pathophysiology, remains poorly understood. We performed in vivo two-photon calcium imaging in neocortex during temperature-induced seizures in male and female Dravet syndrome (Scn1a+/-) mice, a neurodevelopmental disorder with prominent temperature-sensitive epilepsy. Mean activity of both putative principal cells and parvalbumin-positive interneurons (PV-INs) was higher in Scn1a+/- relative to wild-type controls during quiet wakefulness at baseline and at elevated core body temperature. However, wild-type PV-INs showed a progressive synchronization in response to temperature elevation that was absent in PV-INs from Scn1a+/- mice. Hence, PV-IN activity remains intact interictally in Scn1a+/- mice, yet exhibits decreased synchrony immediately before seizure onset. We suggest that impaired PV-IN synchronization may contribute to the transition to the ictal state during temperature-induced seizures in Dravet syndrome.SIGNIFICANCE STATEMENT Epilepsy is a common neurological disorder defined by recurrent, unprovoked seizures. However, basic mechanisms of seizure initiation and propagation remain poorly understood. We performed in vivo two-photon calcium imaging in an experimental model of Dravet syndrome (Scn1a+/- mice)-a severe neurodevelopmental disorder defined by temperature-sensitive, treatment-resistant epilepsy-and record activity of putative excitatory neurons and parvalbumin-positive GABAergic neocortical interneurons (PV-INs) during naturalistic seizures induced by increased core body temperature. PV-IN activity was higher in Scn1a+/- relative to wild-type controls during quiet wakefulness. However, wild-type PV-INs showed progressive synchronization in response to temperature elevation that was absent in PV-INs from Scn1a+/- mice before seizure onset. Hence, impaired PV-IN synchronization may contribute to transition to seizure in Dravet syndrome.
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32
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Shuman T, Aharoni D, Cai DJ, Lee CR, Chavlis S, Page-Harley L, Vetere LM, Feng Y, Yang CY, Mollinedo-Gajate I, Chen L, Pennington ZT, Taxidis J, Flores SE, Cheng K, Javaherian M, Kaba CC, Rao N, La-Vu M, Pandi I, Shtrahman M, Bakhurin KI, Masmanidis SC, Khakh BS, Poirazi P, Silva AJ, Golshani P. Breakdown of spatial coding and interneuron synchronization in epileptic mice. Nat Neurosci 2020; 23:229-238. [PMID: 31907437 PMCID: PMC7259114 DOI: 10.1038/s41593-019-0559-0] [Citation(s) in RCA: 95] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 11/19/2019] [Indexed: 12/19/2022]
Abstract
Temporal lobe epilepsy causes severe cognitive deficits, but the circuit mechanisms remain unknown. Interneuron death and reorganization during epileptogenesis may disrupt the synchrony of hippocampal inhibition. To test this, we simultaneously recorded from the CA1 and dentate gyrus in pilocarpine-treated epileptic mice with silicon probes during head-fixed virtual navigation. We found desynchronized interneuron firing between the CA1 and dentate gyrus in epileptic mice. Since hippocampal interneurons control information processing, we tested whether CA1 spatial coding was altered in this desynchronized circuit, using a novel wire-free miniscope. We found that CA1 place cells in epileptic mice were unstable and completely remapped across a week. This spatial instability emerged around 6 weeks after status epilepticus, well after the onset of chronic seizures and interneuron death. Finally, CA1 network modeling showed that desynchronized inputs can impair the precision and stability of CA1 place cells. Together, these results demonstrate that temporally precise intrahippocampal communication is critical for spatial processing.
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Affiliation(s)
- Tristan Shuman
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA.
| | - Daniel Aharoni
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
- Integrative Center for Learning and Memory, University of California, Los Angeles, Los Angeles, CA, USA
| | - Denise J Cai
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Christopher R Lee
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Spyridon Chavlis
- Institute of Molecular Biology and Biotechnology (IMBB), Foundation for Research and Technology Hellas (FORTH), Heraklion, Greece
| | - Lucia Page-Harley
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Lauren M Vetere
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Yu Feng
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Chen Yi Yang
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Irene Mollinedo-Gajate
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Lingxuan Chen
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Zachary T Pennington
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Jiannis Taxidis
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Sergio E Flores
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Kevin Cheng
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Milad Javaherian
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Christina C Kaba
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Naina Rao
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Mimi La-Vu
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Ioanna Pandi
- Institute of Molecular Biology and Biotechnology (IMBB), Foundation for Research and Technology Hellas (FORTH), Heraklion, Greece
- School of Medicine, University of Crete, Heraklion, Greece
| | - Matthew Shtrahman
- Department of Neurosciences, University of California, San Diego, La Jolla, CA, USA
| | - Konstantin I Bakhurin
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Sotiris C Masmanidis
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Baljit S Khakh
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Panayiota Poirazi
- Institute of Molecular Biology and Biotechnology (IMBB), Foundation for Research and Technology Hellas (FORTH), Heraklion, Greece.
| | - Alcino J Silva
- Integrative Center for Learning and Memory, University of California, Los Angeles, Los Angeles, CA, USA
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
- Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, Los Angeles, CA, USA
- Department of Psychology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Peyman Golshani
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA.
- Integrative Center for Learning and Memory, University of California, Los Angeles, Los Angeles, CA, USA.
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA.
- Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, Los Angeles, CA, USA.
- West LA Veterans Affairs Medical Center, Los Angeles, CA, USA.
- Intellectual and Developmental Disabilities Research Center, University of California, Los Angeles, Los Angeles, CA, USA.
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33
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Shuman T, Aharoni D, Cai DJ, Lee CR, Chavlis S, Page-Harley L, Vetere LM, Feng Y, Yang CY, Mollinedo-Gajate I, Chen L, Pennington ZT, Taxidis J, Flores SE, Cheng K, Javaherian M, Kaba CC, Rao N, La-Vu M, Pandi I, Shtrahman M, Bakhurin KI, Masmanidis SC, Khakh BS, Poirazi P, Silva AJ, Golshani P. Breakdown of spatial coding and interneuron synchronization in epileptic mice. Nat Neurosci 2020. [PMID: 31907437 DOI: 10.1038/s41593-019-0559-0.e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/16/2023]
Abstract
Temporal lobe epilepsy causes severe cognitive deficits, but the circuit mechanisms remain unknown. Interneuron death and reorganization during epileptogenesis may disrupt the synchrony of hippocampal inhibition. To test this, we simultaneously recorded from the CA1 and dentate gyrus in pilocarpine-treated epileptic mice with silicon probes during head-fixed virtual navigation. We found desynchronized interneuron firing between the CA1 and dentate gyrus in epileptic mice. Since hippocampal interneurons control information processing, we tested whether CA1 spatial coding was altered in this desynchronized circuit, using a novel wire-free miniscope. We found that CA1 place cells in epileptic mice were unstable and completely remapped across a week. This spatial instability emerged around 6 weeks after status epilepticus, well after the onset of chronic seizures and interneuron death. Finally, CA1 network modeling showed that desynchronized inputs can impair the precision and stability of CA1 place cells. Together, these results demonstrate that temporally precise intrahippocampal communication is critical for spatial processing.
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Affiliation(s)
- Tristan Shuman
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA.
| | - Daniel Aharoni
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
- Integrative Center for Learning and Memory, University of California, Los Angeles, Los Angeles, CA, USA
| | - Denise J Cai
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Christopher R Lee
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Spyridon Chavlis
- Institute of Molecular Biology and Biotechnology (IMBB), Foundation for Research and Technology Hellas (FORTH), Heraklion, Greece
| | - Lucia Page-Harley
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Lauren M Vetere
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Yu Feng
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Chen Yi Yang
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Irene Mollinedo-Gajate
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Lingxuan Chen
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Zachary T Pennington
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Jiannis Taxidis
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Sergio E Flores
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Kevin Cheng
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Milad Javaherian
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Christina C Kaba
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Naina Rao
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Mimi La-Vu
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Ioanna Pandi
- Institute of Molecular Biology and Biotechnology (IMBB), Foundation for Research and Technology Hellas (FORTH), Heraklion, Greece
- School of Medicine, University of Crete, Heraklion, Greece
| | - Matthew Shtrahman
- Department of Neurosciences, University of California, San Diego, La Jolla, CA, USA
| | - Konstantin I Bakhurin
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Sotiris C Masmanidis
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Baljit S Khakh
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Panayiota Poirazi
- Institute of Molecular Biology and Biotechnology (IMBB), Foundation for Research and Technology Hellas (FORTH), Heraklion, Greece.
| | - Alcino J Silva
- Integrative Center for Learning and Memory, University of California, Los Angeles, Los Angeles, CA, USA
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
- Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, Los Angeles, CA, USA
- Department of Psychology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Peyman Golshani
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA.
- Integrative Center for Learning and Memory, University of California, Los Angeles, Los Angeles, CA, USA.
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA.
- Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, Los Angeles, CA, USA.
- West LA Veterans Affairs Medical Center, Los Angeles, CA, USA.
- Intellectual and Developmental Disabilities Research Center, University of California, Los Angeles, Los Angeles, CA, USA.
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Riquelme J, Wellmann M, Sotomayor-Zárate R, Bonansco C. Gliotransmission: A Novel Target for the Development of Antiseizure Drugs. Neuroscientist 2020; 26:293-309. [PMID: 31976817 DOI: 10.1177/1073858420901474] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
For more than a century, epilepsy has remained an incapacitating neurological disorder with a high incidence worldwide. Mesial temporal lobe epilepsy (TLE) is a common type of epilepsy without an effective pharmacological treatment. An increase in excitability and hypersynchrony of electrical neuronal activity during development are typically associated with an excitatory/inhibitory imbalance in the neuronal network. Astrocytes release gliotransmitters, which can regulate neuronal excitability and synaptic transmission; therefore, the classical neurocentric vision of the cellular basis of epileptogenesis has begun to change. Growing evidence suggests that the key contribution of astrocyte-to-neuron signaling in the mechanisms underlies the initiation, propagation, and recurrence of seizure activity. The aim of this review was to summarize current evidence obtained from experimental models that suggest how alterations in astroglial modulation of synaptic transmission and neuronal activity contribute to the development of this brain disease. In this article, we will summarize the main pharmacological, Ca2+-imaging, and electrophysiological findings in the gliotransmitter-mediated modulation of neuronal activity and their possible regulation as a novel cellular target for the development of pharmacological strategies for treating refractory epilepsies.
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Affiliation(s)
- Julio Riquelme
- Escuela de Medicina, Facultad de Medicina, Universidad de Valparaíso, Valparaíso, Chile.,Servicio de Neurología, Hospital Carlos Van Buren, Valparaíso, Chile
| | - Mario Wellmann
- Escuela de Fonoaudiología, Facultad de Medicina, Universidad de Valparaíso, Valparaíso, Chile.,Centro de Neurobiología y Fisiología Integrativa (CENFI), Instituto de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Ramón Sotomayor-Zárate
- Centro de Neurobiología y Fisiología Integrativa (CENFI), Instituto de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Christian Bonansco
- Centro de Neurobiología y Fisiología Integrativa (CENFI), Instituto de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
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Rich S, Chameh HM, Rafiee M, Ferguson K, Skinner FK, Valiante TA. Inhibitory Network Bistability Explains Increased Interneuronal Activity Prior to Seizure Onset. Front Neural Circuits 2020; 13:81. [PMID: 32009908 PMCID: PMC6972503 DOI: 10.3389/fncir.2019.00081] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Accepted: 12/17/2019] [Indexed: 01/02/2023] Open
Abstract
Recent experimental literature has revealed that GABAergic interneurons exhibit increased activity prior to seizure onset, alongside additional evidence that such activity is synchronous and may arise abruptly. These findings have led some to hypothesize that this interneuronal activity may serve a causal role in driving the sudden change in brain activity that heralds seizure onset. However, the mechanisms predisposing an inhibitory network toward increased activity, specifically prior to ictogenesis, without a permanent change to inputs to the system remain unknown. We address this question by comparing simulated inhibitory networks containing control interneurons and networks containing hyperexcitable interneurons modeled to mimic treatment with 4-Aminopyridine (4-AP), an agent commonly used to model seizures in vivo and in vitro. Our in silico study demonstrates that model inhibitory networks with 4-AP interneurons are more prone than their control counterparts to exist in a bistable state in which asynchronously firing networks can abruptly transition into synchrony driven by a brief perturbation. This transition into synchrony brings about a corresponding increase in overall firing rate. We further show that perturbations driving this transition could arise in vivo from background excitatory synaptic activity in the cortex. Thus, we propose that bistability explains the increase in interneuron activity observed experimentally prior to seizure via a transition from incoherent to coherent dynamics. Moreover, bistability explains why inhibitory networks containing hyperexcitable interneurons are more vulnerable to this change in dynamics, and how such networks can undergo a transition without a permanent change in the drive. We note that while our comparisons are between networks of control and ictogenic neurons, the conclusions drawn specifically relate to the unusual dynamics that arise prior to seizure, and not seizure onset itself. However, providing a mechanistic explanation for this phenomenon specifically in a pro-ictogenic setting generates experimentally testable hypotheses regarding the role of inhibitory neurons in pre-ictal neural dynamics, and motivates further computational research into mechanisms underlying a newly hypothesized multi-step pathway to seizure initiated by inhibition.
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Affiliation(s)
- Scott Rich
- Division of Clinical and Computational Neuroscience, Krembil Research Institute, University Health Network, Toronto, ON, Canada
| | - Homeira Moradi Chameh
- Division of Clinical and Computational Neuroscience, Krembil Research Institute, University Health Network, Toronto, ON, Canada
| | - Marjan Rafiee
- Division of Clinical and Computational Neuroscience, Krembil Research Institute, University Health Network, Toronto, ON, Canada
| | - Katie Ferguson
- Division of Clinical and Computational Neuroscience, Krembil Research Institute, University Health Network, Toronto, ON, Canada
| | - Frances K Skinner
- Division of Clinical and Computational Neuroscience, Krembil Research Institute, University Health Network, Toronto, ON, Canada.,Departments of Medicine (Neurology) and Physiology, University of Toronto, Toronto, ON, Canada
| | - Taufik A Valiante
- Division of Clinical and Computational Neuroscience, Krembil Research Institute, University Health Network, Toronto, ON, Canada.,Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada.,Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, ON, Canada.,Department of Electrical and Computer Engineering, University of Toronto, Toronto, ON, Canada
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36
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Chauvière L. Potential causes of cognitive alterations in temporal lobe epilepsy. Behav Brain Res 2020; 378:112310. [DOI: 10.1016/j.bbr.2019.112310] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 10/15/2019] [Accepted: 10/15/2019] [Indexed: 12/11/2022]
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Aeed F, Shnitzer T, Talmon R, Schiller Y. Layer- and Cell-Specific Recruitment Dynamics during Epileptic Seizures In Vivo. Ann Neurol 2019; 87:97-115. [PMID: 31657482 DOI: 10.1002/ana.25628] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 10/22/2019] [Accepted: 10/22/2019] [Indexed: 12/29/2022]
Abstract
OBJECTIVE To investigate the network dynamics mechanisms underlying differential initiation of epileptic interictal spikes and seizures. METHODS We performed combined in vivo 2-photon calcium imaging from different targeted neuronal subpopulations and extracellular electrophysiological recordings during 4-aminopyridine-induced neocortical spikes and seizures. RESULTS Both spikes and seizures were associated with intense synchronized activation of excitatory layer 2/3 pyramidal neurons (PNs) and to a lesser degree layer 4 neurons, as well as inhibitory parvalbumin-expressing interneurons (INs). In sharp contrast, layer 5 PNs and somatostatin-expressing INs were gradually and asynchronously recruited into the ictal activity during the course of seizures. Within layer 2/3, the main difference between onset of spikes and seizures lay in the relative recruitment dynamics of excitatory PNs compared to parvalbumin- and somatostatin-expressing inhibitory INs. Whereas spikes exhibited balanced recruitment of PNs and parvalbumin-expressing INs, during seizures IN responses were reduced and less synchronized than in layer 2/3 PNs. Similar imbalance was not observed in layers 4 or 5 of the neocortex. Machine learning-based algorithms we developed were able to distinguish spikes from seizures based solely on activation dynamics of layer 2/3 PNs at discharge onset. INTERPRETATION During onset of seizures, the recruitment dynamics markedly differed between neuronal subpopulations, with rapid synchronous recruitment of layer 2/3 PNs, layer 4 neurons, and parvalbumin-expressing INs and gradual asynchronous recruitment of layer 5 PNs and somatostatin-expressing INs. Seizures initiated in layer 2/3 due to a dynamic mismatch between local PNs and inhibitory INs, and only later spread to layer 5 by gradually and asynchronously recruiting PNs in this layer. ANN NEUROL 2020;87:97-115.
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Affiliation(s)
- Fadi Aeed
- Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Tal Shnitzer
- Viterbi Faculty of Electrical Engineering, Technion-Israel Institute of Technology, Haifa, Israel
| | - Ronen Talmon
- Viterbi Faculty of Electrical Engineering, Technion-Israel Institute of Technology, Haifa, Israel
| | - Yitzhak Schiller
- Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.,Department of Neurology, Rambam Medical Center, Haifa, Israel
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38
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Onorato I, Neuenschwander S, Hoy J, Lima B, Rocha KS, Broggini AC, Uran C, Spyropoulos G, Klon-Lipok J, Womelsdorf T, Fries P, Niell C, Singer W, Vinck M. A Distinct Class of Bursting Neurons with Strong Gamma Synchronization and Stimulus Selectivity in Monkey V1. Neuron 2019; 105:180-197.e5. [PMID: 31732258 DOI: 10.1016/j.neuron.2019.09.039] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 07/12/2019] [Accepted: 09/23/2019] [Indexed: 12/12/2022]
Abstract
Cortical computation depends on interactions between excitatory and inhibitory neurons. The contributions of distinct neuron types to sensory processing and network synchronization in primate visual cortex remain largely undetermined. We show that in awake monkey V1, there exists a distinct cell type (››30% of neurons) that has narrow-waveform (NW) action potentials and high spontaneous discharge rates and fires in high-frequency bursts. These neurons are more stimulus selective and phase locked to 30- to 80-Hz gamma oscillations than other neuron types. Unlike other neuron types, their gamma-phase locking is highly predictive of orientation tuning. We find evidence for strong rhythmic inhibition in these neurons, suggesting that they interact with interneurons to act as excitatory pacemakers for the V1 gamma rhythm. We did not find a similar class of NW bursting neurons in L2-L4 of mouse V1. Given its properties, this class of NW bursting neurons should be pivotal for the encoding and transmission of stimulus information.
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Affiliation(s)
- Irene Onorato
- Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, Frankfurt, Germany; International Max Planck Research School for Neural Circuits, Frankfurt am Main, Germany
| | - Sergio Neuenschwander
- Max Planck Institute for Brain Research, Frankfurt, Germany; Brain Institute, Federal University of Rio Grande do Norte, Natal, Brazil
| | - Jennifer Hoy
- Institute of Neuroscience and Department of Biology, University of Oregon, Eugene, OR, USA
| | - Bruss Lima
- Max Planck Institute for Brain Research, Frankfurt, Germany
| | - Katia-Simone Rocha
- Brain Institute, Federal University of Rio Grande do Norte, Natal, Brazil
| | - Ana Clara Broggini
- Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, Frankfurt, Germany
| | - Cem Uran
- Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, Frankfurt, Germany
| | - Georgios Spyropoulos
- Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, Frankfurt, Germany; International Max Planck Research School for Neural Circuits, Frankfurt am Main, Germany
| | - Johanna Klon-Lipok
- Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, Frankfurt, Germany; Max Planck Institute for Brain Research, Frankfurt, Germany
| | | | - Pascal Fries
- Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, Frankfurt, Germany
| | - Cristopher Niell
- Institute of Neuroscience and Department of Biology, University of Oregon, Eugene, OR, USA
| | - Wolf Singer
- Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, Frankfurt, Germany; Max Planck Institute for Brain Research, Frankfurt, Germany; Frankfurt Institute for Advanced Studies, Frankfurt, Germany
| | - Martin Vinck
- Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, Frankfurt, Germany.
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Wenzel M, Hamm JP, Peterka DS, Yuste R. Acute Focal Seizures Start As Local Synchronizations of Neuronal Ensembles. J Neurosci 2019; 39:8562-8575. [PMID: 31427393 PMCID: PMC6807279 DOI: 10.1523/jneurosci.3176-18.2019] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 07/27/2019] [Accepted: 08/09/2019] [Indexed: 11/21/2022] Open
Abstract
Understanding seizure formation and spread remains a critical goal of epilepsy research. We used fast in vivo two-photon calcium imaging in male mouse neocortex to reconstruct, with single-cell resolution, the dynamics of acute (4-aminopyridine) focal cortical seizures as they originate within a spatially confined seizure initiation site (intrafocal region), and subsequently propagate into neighboring cortical areas (extrafocal region). We find that seizures originate as local neuronal ensembles within the initiation site. This abnormal hyperactivity engages increasingly larger areas in a saltatory fashion until it breaks into neighboring cortex, where it proceeds smoothly and is then detected electrophysiologically (LFP). Interestingly, PV inhibitory interneurons have spatially heterogeneous activity in intrafocal and extrafocal territories, ruling out a simple role of inhibition in seizure formation and spread. We propose a two-step model for the progression of focal seizures, where neuronal ensembles activate first, generating a microseizure, followed by widespread neural activation in a traveling wave through neighboring cortex during macroseizures.SIGNIFICANCE STATEMENT We have used calcium imaging in mouse sensory cortex in vivo to reconstruct the onset of focal seizures elicited by local injection of the chemoconvulsant 4-aminopyridine. We demonstrate at cellular resolution that acute focal seizures originate as increasingly synchronized local neuronal ensembles. Because of its spatial confinement, this process may at first be undetectable even by nearby LFP electrodes. Further, we establish spatial footprints of local neural subtype activity that correspond to consecutive steps of seizure microprogression. Such footprints could facilitate determining the recording location (e.g., inside/outside an epileptogenic focus) in high-resolution studies, even in the absence of a priori knowledge about where exactly a seizure started.
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Affiliation(s)
- Michael Wenzel
- Neurotechnology Center, Department of Biological Sciences, Columbia University, New York, New York 10027
| | - Jordan P Hamm
- Neurotechnology Center, Department of Biological Sciences, Columbia University, New York, New York 10027
| | - Darcy S Peterka
- Neurotechnology Center, Department of Biological Sciences, Columbia University, New York, New York 10027
| | - Rafael Yuste
- Neurotechnology Center, Department of Biological Sciences, Columbia University, New York, New York 10027
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40
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Tryba AK, Merricks EM, Lee S, Pham T, Cho S, Nordli DR, Eissa TL, Goodman RR, McKhann GM, Emerson RG, Schevon CA, van Drongelen W. Role of paroxysmal depolarization in focal seizure activity. J Neurophysiol 2019; 122:1861-1873. [PMID: 31461373 DOI: 10.1152/jn.00392.2019] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
We analyze the role of inhibition in sustaining focal epileptic seizure activity. We review ongoing seizure activity at the mesoscopic scale that can be observed with microelectrode arrays as well as at the macroscale of standard clinical EEG. We provide clinical, experimental, and modeling data to support the hypothesis that paroxysmal depolarization (PD) is a critical component of the ictal machinery. We present dual-patch recordings in cortical cultures showing reduced synaptic transmission associated with presynaptic occurrence of PD, and we find that the PD threshold is cell size related. We further find evidence that optically evoked PD activity in parvalbumin neurons can promote propagation of neuronal excitation in neocortical networks in vitro. Spike sorting results from microelectrode array measurements around ictal wave propagation in human focal seizures demonstrate a strong increase in putative inhibitory firing with an approaching excitatory wave, followed by a sudden reduction of firing at passage. At the macroscopic level, we summarize evidence that this excitatory ictal wave activity is strongly correlated with oscillatory activity across a centimeter-sized cortical network. We summarize Wilson-Cowan-type modeling showing how inhibitory function is crucial for this behavior. Our findings motivated us to develop a network motif of neurons in silico, governed by a reduced version of the Hodgkin-Huxley formalism, to show how feedforward, feedback, PD, and local failure of inhibition contribute to observed dynamics across network scales. The presented multidisciplinary evidence suggests that the PD not only is a cellular marker or epiphenomenon but actively contributes to seizure activity.NEW & NOTEWORTHY We present mechanisms of ongoing focal seizures across meso- and macroscales of microelectrode array and standard clinical recordings, respectively. We find modeling, experimental, and clinical evidence for a dual role of inhibition across these scales: local failure of inhibition allows propagation of a mesoscopic ictal wave, whereas inhibition elsewhere remains intact and sustains macroscopic oscillatory activity. We present evidence for paroxysmal depolarization as a mechanism behind this dual role of inhibition in shaping ictal activity.
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Affiliation(s)
- Andrew K Tryba
- Section of Neurology, Department of Pediatrics, The University of Chicago, Chicago, Illinois
| | - Edward M Merricks
- Department of Neurology, Columbia University Medical Center, New York, New York
| | - Somin Lee
- Section of Neurology, Department of Pediatrics, The University of Chicago, Chicago, Illinois
| | - Tuan Pham
- Section of Neurology, Department of Pediatrics, The University of Chicago, Chicago, Illinois
| | - SungJun Cho
- Section of Neurology, Department of Pediatrics, The University of Chicago, Chicago, Illinois
| | - Douglas R Nordli
- Section of Neurology, Department of Pediatrics, The University of Chicago, Chicago, Illinois
| | - Tahra L Eissa
- Department of Applied Mathematics, University of Colorado Boulder, Boulder, Colorado
| | - Robert R Goodman
- Department of Neurosurgery, Northwell Health/Lenox Hill Hospital, New York, New York
| | - Guy M McKhann
- Department of Neurological Surgery, Columbia University Medical Center, New York, New York
| | | | - Catherine A Schevon
- Department of Neurology, Columbia University Medical Center, New York, New York
| | - Wim van Drongelen
- Section of Neurology, Department of Pediatrics, The University of Chicago, Chicago, Illinois
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41
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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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42
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Parrish RR, Codadu NK, Mackenzie-Gray Scott C, Trevelyan AJ. Feedforward inhibition ahead of ictal wavefronts is provided by both parvalbumin- and somatostatin-expressing interneurons. J Physiol 2019; 597:2297-2314. [PMID: 30784081 PMCID: PMC6462485 DOI: 10.1113/jp277749] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 02/19/2019] [Indexed: 12/29/2022] Open
Abstract
Key points There is a rapid interneuronal response to focal activity in cortex, which restrains laterally propagating activity, including spreading epileptiform activity. The interneuronal response involves intense activation of both parvalbumin‐ and somatostatin‐expressing interneurons. Interneuronal bursting is time‐locked to glutamatergic barrages in the pre‐ictal period. Ca2+ imaging using conditional expression of GCaMP6f provides an accurate readout of the evolving firing patterns in both types of interneuron. The activation profiles of the two interneuronal classes are temporally offset, with the parvalbumin population being activated first, and typically, at higher rates.
Abstract Previous work has described powerful restraints on laterally spreading activity in cortical networks, arising from a rapid feedforward interneuronal response to focal activity. This response is particularly prominent ahead of an ictal wavefront. Parvalbumin‐positive interneurons are considered to be critically involved in this feedforward inhibition, but it is not known what role, if any, is provided by somatostatin‐expressing interneurons, which target the distal dendrites of pyramidal cells. We used a combination of electrophysiology and cell class‐specific Ca2+ imaging in mouse brain slices bathed in 0 Mg2+ medium to characterize the activity profiles of pyramidal cells and parvalbumin‐ and somatostatin‐expressing interneurons during epileptiform activation. The GCaMP6f signal strongly correlates with the level of activity for both interneuronal classes. Both interneuronal classes participate in the feedfoward inhibition. This contrasts starkly with the pattern of pyramidal recruitment, which is greatly delayed. During these barrages, both sets of interneurons show intense bursting, at rates up to 300Hz, which is time‐locked to the glutamatergic barrages. The activity of parvalbumin‐expressing interneurons appears to peak early in the pre‐ictal period, and can display depolarizing block during the ictal event. In contrast, somatostatin‐expressing interneuronal activity peaks significantly later, and firing persists throughout the ictal events. Interictal events appear to be very similar to the pre‐ictal period, albeit with slightly lower firing rates. Thus, the inhibitory restraint arises from a coordinated pattern of activity in the two main classes of cortical interneurons. There is a rapid interneuronal response to focal activity in cortex, which restrains laterally propagating activity, including spreading epileptiform activity. The interneuronal response involves intense activation of both parvalbumin‐ and somatostatin‐expressing interneurons. Interneuronal bursting is time‐locked to glutamatergic barrages in the pre‐ictal period. Ca2+ imaging using conditional expression of GCaMP6f provides an accurate readout of the evolving firing patterns in both types of interneuron. The activation profiles of the two interneuronal classes are temporally offset, with the parvalbumin population being activated first, and typically, at higher rates.
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Affiliation(s)
- R Ryley Parrish
- Institute of Neuroscience, Medical School, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Neela K Codadu
- Institute of Neuroscience, Medical School, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | | | - Andrew J Trevelyan
- Institute of Neuroscience, Medical School, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
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43
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Abstract
Optogenetic study in vivo demonstrates that different types of interneurons show consistently elevated but distinct firing patterns in the period preceding seizure onset in a rodent model of epilepsy.
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Affiliation(s)
- Laura C. Andreae
- MRC Centre for Neurodevelopmental Disorders, King’s College London, London SE1 1UL, UK
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