1
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Ferrero JJ, Hassan AR, Yu Z, Zhao Z, Ma L, Wu C, Shao S, Kawano T, Engel J, Doyle W, Devinsky O, Khodagholy D, Gelinas JN. Closed-loop electrical stimulation to prevent focal epilepsy progression and long-term memory impairment. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.09.579660. [PMID: 38405990 PMCID: PMC10888806 DOI: 10.1101/2024.02.09.579660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Interictal epileptiform discharges (IEDs) are ubiquitously expressed in epileptic networks and disrupt cognitive functions. It is unclear whether addressing IED-induced dysfunction could improve epilepsy outcomes as most therapeutics target seizures. We show in a model of progressive hippocampal epilepsy that IEDs produce pathological oscillatory coupling which is associated with prolonged, hypersynchronous neural spiking in synaptically connected cortex and expands the brain territory capable of generating IEDs. A similar relationship between IED-mediated oscillatory coupling and temporal organization of IEDs across brain regions was identified in human subjects with refractory focal epilepsy. Spatiotemporally targeted closed-loop electrical stimulation triggered on hippocampal IED occurrence eliminated the abnormal cortical activity patterns, preventing spread of the epileptic network and ameliorating long-term spatial memory deficits in rodents. These findings suggest that stimulation-based network interventions that normalize interictal dynamics may be an effective treatment of epilepsy and its comorbidities, with a low barrier to clinical translation. One-Sentence Summary Targeted closed-loop electrical stimulation prevents spread of the epileptic network and ameliorates long-term spatial memory deficits.
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Boileau C, Deforges S, Peret A, Scavarda D, Bartolomei F, Giles A, Partouche N, Gautron J, Viotti J, Janowitz H, Penchet G, Marchal C, Lagarde S, Trebuchon A, Villeneuve N, Rumi J, Marissal T, Khazipov R, Khalilov I, Martineau F, Maréchal M, Lepine A, Milh M, Figarella-Branger D, Dougy E, Tong S, Appay R, Baudouin S, Mercer A, Smith JB, Danos O, Porter R, Mulle C, Crépel V. GluK2 Is a Target for Gene Therapy in Drug-Resistant Temporal Lobe Epilepsy. Ann Neurol 2023; 94:745-761. [PMID: 37341588 DOI: 10.1002/ana.26723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 06/09/2023] [Accepted: 06/12/2023] [Indexed: 06/22/2023]
Abstract
OBJECTIVE Temporal lobe epilepsy (TLE) is characterized by recurrent seizures generated in the limbic system, particularly in the hippocampus. In TLE, recurrent mossy fiber sprouting from dentate gyrus granule cells (DGCs) crea an aberrant epileptogenic network between DGCs which operates via ectopically expressed GluK2/GluK5-containing kainate receptors (KARs). TLE patients are often resistant to anti-seizure medications and suffer significant comorbidities; hence, there is an urgent need for novel therapies. Previously, we have shown that GluK2 knockout mice are protected from seizures. This study aims at providing evidence that downregulating KARs in the hippocampus using gene therapy reduces chronic epileptic discharges in TLE. METHODS We combined molecular biology and electrophysiology in rodent models of TLE and in hippocampal slices surgically resected from patients with drug-resistant TLE. RESULTS Here, we confirmed the translational potential of KAR suppression using a non-selective KAR antagonist that markedly attenuated interictal-like epileptiform discharges (IEDs) in TLE patient-derived hippocampal slices. An adeno-associated virus (AAV) serotype-9 vector expressing anti-grik2 miRNA was engineered to specifically downregulate GluK2 expression. Direct delivery of AAV9-anti grik2 miRNA into the hippocampus of TLE mice led to a marked reduction in seizure activity. Transduction of TLE patient hippocampal slices reduced levels of GluK2 protein and, most importantly, significantly reduced IEDs. INTERPRETATION Our gene silencing strategy to knock down aberrant GluK2 expression demonstrates inhibition of chronic seizure in a mouse TLE model and IEDs in cultured slices derived from TLE patients. These results provide proof-of-concept for a gene therapy approach targeting GluK2 KARs for drug-resistant TLE patients. ANN NEUROL 2023;94:745-761.
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Affiliation(s)
| | - Severine Deforges
- Univ. Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience IINS, UMR 5297, Bordeaux, France
| | | | - Didier Scavarda
- APHM, INSERM, Aix Marseille Univ, INS, Timone Hospital, Pediatric Neurosurgery, Marseille, France
| | - Fabrice Bartolomei
- APHM, INSERM, Aix Marseille Univ, INS, Timone Hospital, Epileptology Department, Marseille, France
| | | | - Nicolas Partouche
- Aix-Marseille Univ. INSERM, Marseille, France
- Corlieve Therapeutics SAS, uniQure NV, Paris, France
| | - Justine Gautron
- Univ. Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience IINS, UMR 5297, Bordeaux, France
- Corlieve Therapeutics SAS, uniQure NV, Paris, France
| | - Julio Viotti
- Univ. Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience IINS, UMR 5297, Bordeaux, France
| | | | | | - Cécile Marchal
- Pellegrin Hospital, Neurosurgery Department, Bordeaux, France
| | - Stanislas Lagarde
- APHM, INSERM, Aix Marseille Univ, INS, Timone Hospital, Epileptology Department, Marseille, France
| | - Agnès Trebuchon
- APHM, INSERM, Aix Marseille Univ, INS, Timone Hospital, Epileptology Department, Marseille, France
| | - Nathalie Villeneuve
- APHM, INSERM, Aix Marseille Univ, INS, Timone Hospital, Epileptology Department, Marseille, France
| | - Julie Rumi
- Univ. Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience IINS, UMR 5297, Bordeaux, France
| | | | | | | | | | - Marine Maréchal
- Univ. Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience IINS, UMR 5297, Bordeaux, France
| | - Anne Lepine
- APHM, INSERM, Aix Marseille Univ, INS, Timone Hospital, Epileptology Department, Marseille, France
| | - Mathieu Milh
- APHM, INSERM, Aix Marseille Univ, INS, Timone Hospital, Epileptology Department, Marseille, France
| | - Dominique Figarella-Branger
- APHM, CNRS, INP, Inst Neurophysiopathol, CHU Timone, Service d'Anatomie Pathologique et de Neuropathologie, Aix-Marseille Univ, Marseille, France
| | - Etienne Dougy
- APHM, CNRS, INP, Inst Neurophysiopathol, CHU Timone, Service d'Anatomie Pathologique et de Neuropathologie, Aix-Marseille Univ, Marseille, France
| | - Soutsakhone Tong
- APHM, CNRS, INP, Inst Neurophysiopathol, CHU Timone, Service d'Anatomie Pathologique et de Neuropathologie, Aix-Marseille Univ, Marseille, France
| | - Romain Appay
- APHM, CNRS, INP, Inst Neurophysiopathol, CHU Timone, Service d'Anatomie Pathologique et de Neuropathologie, Aix-Marseille Univ, Marseille, France
| | | | | | | | | | | | - Christophe Mulle
- Univ. Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience IINS, UMR 5297, Bordeaux, France
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Goirand-Lopez L, Moulinier M, Vigier A, Boileau C, Carleton A, Muldoon SF, Marissal T, Crépel V. Kainate receptors modulate the microstructure of synchrony during dentate gyrus epileptiform activity. Neurobiol Dis 2023; 185:106260. [PMID: 37573957 DOI: 10.1016/j.nbd.2023.106260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 07/28/2023] [Accepted: 08/11/2023] [Indexed: 08/15/2023] Open
Abstract
Temporal Lobe Epilepsy (TLE) is the most common form of epilepsy in adults. In TLE, recurrent mossy fiber (rMF) sprouting from dentate gyrus granule cells (DGCs) forms an aberrant epileptogenic network between dentate granule cells (DGCs) that operates via ectopically expressed kainate receptors (KARs). It was previously shown that KARs expressed at the rMF-DGC synapses play a prominent role in epileptiform network events in TLE. However, it is not well understood how KARs influence neuronal network dynamics and contribute to the generation of epileptiform network activity in the dentate gyrus. To address this question, we monitored the activity of DGCs using single-cell resolution calcium imaging performed in a reliable in vitro model of TLE. Under our experimental conditions, the most prominent DGC activity patterns were interictal-like epileptiform network events, which were correlated with high levels of neuronal synchronization. The pharmacological blockade of KARs reduced the frequency as well as the number of neurons involved in these events, without altering their spatiotemporal dynamics. Analysis of the microstructure of synchrony showed that blockade of KARs diminished the fraction of neurons forming the main functional cluster. Therefore, we propose that KARs act as modulators in the epileptic network by facilitating the recruitment of neurons into coactive cell assemblies, thereby contributing to the occurrence of epileptiform network events.
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Affiliation(s)
| | - Marie Moulinier
- Department of Basic Neuroscience, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | | | | | - Alan Carleton
- Department of Basic Neuroscience, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Sarah F Muldoon
- Mathematics Department, Institute for Artificial Intelligence and Data Science, and Neuroscience Program, University at Buffalo, SUNY, Buffalo NY14260, USA
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4
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Diamond JM, Withers CP, Chapeton JI, Rahman S, Inati SK, Zaghloul KA. Interictal discharges in the human brain are travelling waves arising from an epileptogenic source. Brain 2023; 146:1903-1915. [PMID: 36729683 PMCID: PMC10411927 DOI: 10.1093/brain/awad015] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 12/27/2022] [Accepted: 01/08/2023] [Indexed: 02/03/2023] Open
Abstract
While seizure activity may be electrographically widespread, increasing evidence has suggested that ictal discharges may in fact represent travelling waves propagated from a focal seizure source. Interictal epileptiform discharges (IEDs) are an electrographic manifestation of excessive hypersynchronization of cortical activity that occur between seizures and are considered a marker of potentially epileptogenic tissue. The precise relationship between brain regions demonstrating IEDs and those involved in seizure onset, however, remains poorly understood. Here, we hypothesize that IEDs likewise reflect the receipt of travelling waves propagated from the same regions which give rise to seizures. Forty patients from our institution who underwent invasive monitoring for epilepsy, proceeded to surgery and had at least one year of follow-up were included in our study. Interictal epileptiform discharges were detected using custom software, validated by a clinical epileptologist. We show that IEDs reach electrodes in sequences with a consistent temporal ordering, and this ordering matches the timing of receipt of ictal discharges, suggesting that both types of discharges spread as travelling waves. We use a novel approach for localization of ictal discharges, in which time differences of discharge receipt at nearby electrodes are used to compute source location; similar algorithms have been used in acoustics and geophysics. We find that interictal discharges co-localize with ictal discharges. Moreover, interictal discharges tend to localize to the resection territory in patients with good surgical outcome and outside of the resection territory in patients with poor outcome. The seizure source may originate at, and also travel to, spatially distinct IED foci. Our data provide evidence that interictal discharges may represent travelling waves of pathological activity that are similar to their ictal counterparts, and that both ictal and interictal discharges emerge from common epileptogenic brain regions. Our findings have important clinical implications, as they suggest that seizure source localizations may be derived from interictal discharges, which are much more frequent than seizures.
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Affiliation(s)
- Joshua M Diamond
- Surgical Neurology Branch, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
| | - C Price Withers
- Clinical Epilepsy Section, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
| | - Julio I Chapeton
- Surgical Neurology Branch, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
| | - Shareena Rahman
- Office of the Clinical Director, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
| | - Sara K Inati
- Clinical Epilepsy Section, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kareem A Zaghloul
- Surgical Neurology Branch, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
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5
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Avoli M, de Curtis M, Lévesque M, Librizzi L, Uva L, Wang S. GABAA signaling, focal epileptiform synchronization and epileptogenesis. Front Neural Circuits 2022; 16:984802. [PMID: 36275847 PMCID: PMC9581276 DOI: 10.3389/fncir.2022.984802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Accepted: 09/13/2022] [Indexed: 12/04/2022] Open
Abstract
Under physiological conditions, neuronal network synchronization leads to different oscillatory EEG patterns that are associated with specific behavioral and cognitive functions. Excessive synchronization can, however, lead to focal or generalized epileptiform activities. It is indeed well established that in both epileptic patients and animal models, focal epileptiform EEG patterns are characterized by interictal and ictal (seizure) discharges. Over the last three decades, employing in vitro and in vivo recording techniques, several experimental studies have firmly identified a paradoxical role of GABAA signaling in generating interictal discharges, and in initiating—and perhaps sustaining—focal seizures. Here, we will review these experiments and we will extend our appraisal to evidence suggesting that GABAA signaling may also contribute to epileptogenesis, i.e., the development of plastic changes in brain excitability that leads to the chronic epileptic condition. Overall, we anticipate that this information should provide the rationale for developing new specific pharmacological treatments for patients presenting with focal epileptic disorders such as mesial temporal lobe epilepsy (MTLE).
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Affiliation(s)
- Massimo Avoli
- Montreal Neurological Institute-Hospital, Montreal, QC, Canada
- Departments of Neurology and Neurosurgery, Montreal, QC, Canada
- Department of Physiology, McGill University, Montreal, QC, Canada
- *Correspondence: Massimo Avoli,
| | - Marco de Curtis
- Epilepsy Unit, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Istituto Neurologico Carlo Besta, Milan, Italy
| | - Maxime Lévesque
- Montreal Neurological Institute-Hospital, Montreal, QC, Canada
- Departments of Neurology and Neurosurgery, Montreal, QC, Canada
| | - Laura Librizzi
- Epilepsy Unit, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Istituto Neurologico Carlo Besta, Milan, Italy
| | - Laura Uva
- Epilepsy Unit, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Istituto Neurologico Carlo Besta, Milan, Italy
| | - Siyan Wang
- Montreal Neurological Institute-Hospital, Montreal, QC, Canada
- Departments of Neurology and Neurosurgery, Montreal, QC, Canada
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6
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Curot J, Barbeau E, Despouy E, Denuelle M, Sol JC, Lotterie JA, Valton L, Peyrache A. Local neuronal excitation and global inhibition during epileptic fast ripples in humans. Brain 2022; 146:561-575. [PMID: 36093747 PMCID: PMC9924905 DOI: 10.1093/brain/awac319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 07/01/2022] [Accepted: 08/01/2022] [Indexed: 11/12/2022] Open
Abstract
Understanding the neuronal basis of epileptic activity is a major challenge in neurology. Cellular integration into larger scale networks is all the more challenging. In the local field potential, interictal epileptic discharges can be associated with fast ripples (200-600 Hz), which are a promising marker of the epileptogenic zone. Yet, how neuronal populations in the epileptogenic zone and in healthy tissue are affected by fast ripples remain unclear. Here, we used a novel 'hybrid' macro-micro depth electrode in nine drug-resistant epileptic patients, combining classic depth recording of local field potentials (macro-contacts) and two or three tetrodes (four micro-wires bundled together) enabling up to 15 neurons in local circuits to be simultaneously recorded. We characterized neuronal responses (190 single units) with the timing of fast ripples (2233 fast ripples) on the same hybrid and other electrodes that target other brain regions. Micro-wire recordings reveal signals that are not visible on macro-contacts. While fast ripples detected on the closest macro-contact to the tetrodes were always associated with fast ripples on the tetrodes, 82% of fast ripples detected on tetrodes were associated with detectable fast ripples on the nearest macro-contact. Moreover, neuronal recordings were taken in and outside the epileptogenic zone of implanted epileptic subjects and they revealed an interlay of excitation and inhibition across anatomical scales. While fast ripples were associated with increased neuronal activity in very local circuits only, they were followed by inhibition in large-scale networks (beyond the epileptogenic zone, even in healthy cortex). Neuronal responses to fast ripples were homogeneous in local networks but differed across brain areas. Similarly, post-fast ripple inhibition varied across recording locations and subjects and was shorter than typical inter-fast ripple intervals, suggesting that this inhibition is a fundamental refractory process for the networks. These findings demonstrate that fast ripples engage local and global networks, including healthy tissue, and point to network features that pave the way for new diagnostic and therapeutic strategies. They also reveal how even localized pathological brain dynamics can affect a broad range of cognitive functions.
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Affiliation(s)
- Jonathan Curot
- Correspondence to: Jonathan Curot, MD, PhD CerCo CNRS UMR 5549, Université Toulouse III CHU Purpan, Pavillon Baudot, 31052 Toulouse Cedex, France E-mail:
| | - Emmanuel Barbeau
- Brain and Cognition Research Center (CerCo), Centre National de la Recherche Scientifique, UMR5549, Toulouse, France,Faculty of Health, University of Toulouse, Paul Sabatier University, Toulouse, France
| | - Elodie Despouy
- Brain and Cognition Research Center (CerCo), Centre National de la Recherche Scientifique, UMR5549, Toulouse, France
| | - Marie Denuelle
- Departments of Neurology and Neurosurgery, Toulouse University Hospital, Toulouse, France,Brain and Cognition Research Center (CerCo), Centre National de la Recherche Scientifique, UMR5549, Toulouse, France
| | - Jean Christophe Sol
- Departments of Neurology and Neurosurgery, Toulouse University Hospital, Toulouse, France,Faculty of Health, University of Toulouse, Paul Sabatier University, Toulouse, France,Toulouse Neuro Imaging Center (ToNIC), INSERM, U1214, Toulouse, France
| | - Jean-Albert Lotterie
- Departments of Neurology and Neurosurgery, Toulouse University Hospital, Toulouse, France,Toulouse Neuro Imaging Center (ToNIC), INSERM, U1214, Toulouse, France
| | - Luc Valton
- Departments of Neurology and Neurosurgery, Toulouse University Hospital, Toulouse, France,Brain and Cognition Research Center (CerCo), Centre National de la Recherche Scientifique, UMR5549, Toulouse, France
| | - Adrien Peyrache
- Correspondence may also be addressed to: Adrien Peyrache, PhD Montreal Neurological Institute Department of Neurology and Neurosurgery McGill University, 3810 University Street Montreal, Quebec, Canada E-mail:
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7
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Subramanian M, Chiang CC, Couturier NH, Durand DM. Theta waves, neural spikes and seizures can propagate by ephaptic coupling in vivo. Exp Neurol 2022; 354:114109. [PMID: 35551899 PMCID: PMC10214533 DOI: 10.1016/j.expneurol.2022.114109] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 04/30/2022] [Accepted: 05/05/2022] [Indexed: 11/29/2022]
Abstract
Electric field coupling has been shown to be responsible for non-synaptic neural activity propagation in hippocampal slices and cortical slices. Epileptiform and slow-wave sleep activity can propagate by electric field coupling without using synaptic connections at speeds of ~0.1 m/s in vitro. However, the characteristics of the events that can propagate using electric field coupling through a volume conductor in vivo have not been studied. Thus, we tested the hypothesis that various types of neural signals such as interictal spikes, theta waves and seizures could propagate in vivo across a transection in the hippocampus. We induced epileptiform activity in 4 rats under anesthesia by injecting 4-aminopyridine in the temporal region of the hippocampus, four recording electrodes were inserted along the longitudinal axis of the hippocampus. A transection was made between the electrodes to study the propagation of the neural activity. Although 54% of the interictal spikes could propagate through the cut, only those spikes with a high amplitude and short duration had a high probability to do so. 70% of seizure events could propagate through the cut but parameters distinguishing between propagating and non-propagating seizure events could not be identified. Theta activity was also observed to propagate at a mean speed of 0.16 ± 0.12 m/s in the characteristic range of propagation using electric field coupling through the transection. The electric field volume conduction mechanism was confirmed by showing that propagation was blocked by placing a dielectric layer within the cut. The speed of propagation was not affected by the transection thereby providing further evidence that various types of neural signals including activity in the theta range can propagate by electric field coupling in-vivo.
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Affiliation(s)
- Muthumeenakshi Subramanian
- Neural Engineering Center, Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Chia-Chu Chiang
- Neural Engineering Center, Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Nicholas H Couturier
- Neural Engineering Center, Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Dominique M Durand
- Neural Engineering Center, Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA.
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8
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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: 11] [Impact Index Per Article: 5.5] [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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9
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Guth TA, Kunz L, Brandt A, Dümpelmann M, Klotz KA, Reinacher PC, Schulze-Bonhage A, Jacobs J, Schönberger J. Interictal spikes with and without high-frequency oscillation have different single-neuron correlates. Brain 2021; 144:3078-3088. [PMID: 34343264 PMCID: PMC8634126 DOI: 10.1093/brain/awab288] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 06/07/2021] [Accepted: 07/06/2021] [Indexed: 11/13/2022] Open
Abstract
Interictal epileptiform discharges (IEDs) are a widely used biomarker in patients with epilepsy but lack specificity. It has been proposed that there are truly epileptogenic and less pathological or even protective IEDs. Recent studies suggest that highly pathological IEDs are characterized by high-frequency oscillations (HFOs). Here, we aimed to dissect these 'HFO-IEDs' at the single-neuron level, hypothesizing that the underlying mechanisms are distinct from 'non-HFO-IEDs'. Analysing hybrid depth electrode recordings from patients with temporal lobe epilepsy, we found that single-unit firing rates were higher in HFO- than in non-HFO-IEDs. HFO-IEDs were characterized by a pronounced pre-peak increase in firing, which coincided with the preferential occurrence of HFOs, whereas in non-HFO-IEDs, there was only a mild pre-peak increase followed by a post-peak suppression. Comparing each unit's firing during HFO-IEDs to its baseline activity, we found many neurons with a significant increase during the HFO component or ascending part, but almost none with a decrease. No such imbalance was observed during non-HFO-IEDs. Finally, comparing each unit's firing directly between HFO- and non-HFO-IEDs, we found that most cells had higher rates during HFO-IEDs and, moreover, identified a distinct subset of neurons with a significant preference for this IED subtype. In summary, our study reveals that HFO- and non-HFO-IEDs have different single-unit correlates. In HFO-IEDs, many neurons are moderately activated, and some participate selectively, suggesting that both types of increased firing contribute to highly pathological IEDs.
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Affiliation(s)
- Tim A Guth
- Epilepsy Center, Medical Center, University of Freiburg, Freiburg, Germany
- Department of Neuropediatrics and Muscle Disorders, Medical Center, University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Lukas Kunz
- Epilepsy Center, Medical Center, University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Department of Biomedical Engineering, Columbia University, New York, NY, USA
- Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, Freiburg, Germany
- Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Armin Brandt
- Epilepsy Center, Medical Center, University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Matthias Dümpelmann
- Epilepsy Center, Medical Center, University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Kerstin A Klotz
- Epilepsy Center, Medical Center, University of Freiburg, Freiburg, Germany
- Department of Neuropediatrics and Muscle Disorders, Medical Center, University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Berta-Ottenstein-Programme, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Peter C Reinacher
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Stereotactic and Functional Neurosurgery, Medical Center—University of Freiburg, Freiburg, Germany
- Fraunhofer Institute for Laser Technology, Aachen, Germany
| | - Andreas Schulze-Bonhage
- Epilepsy Center, Medical Center, University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Julia Jacobs
- Department of Neuropediatrics and Muscle Disorders, Medical Center, University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Department of Paediatrics and Department of Neuroscience, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute and Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Jan Schönberger
- Epilepsy Center, Medical Center, University of Freiburg, Freiburg, Germany
- Department of Neuropediatrics and Muscle Disorders, Medical Center, University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Berta-Ottenstein-Programme, Faculty of Medicine, University of Freiburg, Freiburg, Germany
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10
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Laohathai C, Ebersole JS, Mosher JC, Bagić AI, Sumida A, Von Allmen G, Funke ME. Practical Fundamentals of Clinical MEG Interpretation in Epilepsy. Front Neurol 2021; 12:722986. [PMID: 34721261 PMCID: PMC8551575 DOI: 10.3389/fneur.2021.722986] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 09/06/2021] [Indexed: 11/29/2022] Open
Abstract
Magnetoencephalography (MEG) is a neurophysiologic test that offers a functional localization of epileptic sources in patients considered for epilepsy surgery. The understanding of clinical MEG concepts, and the interpretation of these clinical studies, are very involving processes that demand both clinical and procedural expertise. One of the major obstacles in acquiring necessary proficiency is the scarcity of fundamental clinical literature. To fill this knowledge gap, this review aims to explain the basic practical concepts of clinical MEG relevant to epilepsy with an emphasis on single equivalent dipole (sECD), which is one the most clinically validated and ubiquitously used source localization method, and illustrate and explain the regional topology and source dynamics relevant for clinical interpretation of MEG-EEG.
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Affiliation(s)
- Christopher Laohathai
- Division of Child Neurology, Department of Pediatrics, McGovern Medical School at UTHealth, Houston, TX, United States
- Department of Neurology, Saint Louis University, Saint Louis, MO, United States
| | - John S. Ebersole
- Northeast Regional Epilepsy Group, Atlantic Health Neuroscience Institute, Summit, NJ, United States
| | - John C. Mosher
- Department of Neurology, McGovern Medical School at UTHealth, Houston, TX, United States
| | - Anto I. Bagić
- University of Pittsburgh Comprehensive Epilepsy Center (UPCEC), Department of Neurology, University of Pittsburgh Medical Center, Pittsburg, PA, United States
| | - Ai Sumida
- Department of Neurology, McGovern Medical School at UTHealth, Houston, TX, United States
| | - Gretchen Von Allmen
- Division of Child Neurology, Department of Pediatrics, McGovern Medical School at UTHealth, Houston, TX, United States
| | - Michael E. Funke
- Division of Child Neurology, Department of Pediatrics, McGovern Medical School at UTHealth, Houston, TX, United States
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11
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Yang JC, Paulk AC, Salami P, Lee SH, Ganji M, Soper DJ, Cleary D, Simon M, Maus D, Lee JW, Nahed BV, Jones PS, Cahill DP, Cosgrove GR, Chu CJ, Williams Z, Halgren E, Dayeh S, Cash SS. Microscale dynamics of electrophysiological markers of epilepsy. Clin Neurophysiol 2021; 132:2916-2931. [PMID: 34419344 DOI: 10.1016/j.clinph.2021.06.024] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 06/22/2021] [Accepted: 06/29/2021] [Indexed: 10/20/2022]
Abstract
OBJECTIVE Interictal discharges (IIDs) and high frequency oscillations (HFOs) are established neurophysiologic biomarkers of epilepsy, while microseizures are less well studied. We used custom poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) microelectrodes to better understand these markers' microscale spatial dynamics. METHODS Electrodes with spatial resolution down to 50 µm were used to record intraoperatively in 30 subjects. IIDs' degree of spread and spatiotemporal paths were generated by peak-tracking followed by clustering. Repeating HFO patterns were delineated by clustering similar time windows. Multi-unit activity (MUA) was analyzed in relation to IID and HFO timing. RESULTS We detected IIDs encompassing the entire array in 93% of subjects, while localized IIDs, observed across < 50% of channels, were seen in 53%. IIDs traveled along specific paths. HFOs appeared in small, repeated spatiotemporal patterns. Finally, we identified microseizure events that spanned 50-100 µm. HFOs covaried with MUA, but not with IIDs. CONCLUSIONS Overall, these data suggest that irritable cortex micro-domains may form part of an underlying pathologic architecture which could contribute to the seizure network. SIGNIFICANCE These results, supporting the possibility that epileptogenic cortex comprises a mosaic of irritable domains, suggests that microscale approaches might be an important perspective in devising novel seizure control therapies.
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Affiliation(s)
- Jimmy C Yang
- Department of Neurosurgery, Massachusetts General Hospital, 55 Fruit St., Boston, MA 02114, USA; Department of Neurology, Massachusetts General Hospital, 55 Fruit St., Boston, MA 02114, USA
| | - Angelique C Paulk
- Department of Neurology, Massachusetts General Hospital, 55 Fruit St., Boston, MA 02114, USA
| | - Pariya Salami
- Department of Neurology, Massachusetts General Hospital, 55 Fruit St., Boston, MA 02114, USA
| | - Sang Heon Lee
- Department of Electrical and Computer Engineering, University of California, San Diego; 9500 Gilman Dr., La Jolla, CA 92093, USA
| | - Mehran Ganji
- Department of Electrical and Computer Engineering, University of California, San Diego; 9500 Gilman Dr., La Jolla, CA 92093, USA
| | - Daniel J Soper
- Department of Neurology, Massachusetts General Hospital, 55 Fruit St., Boston, MA 02114, USA
| | - Daniel Cleary
- Department of Neurosurgery, University of California, San Diego; 9500 Gilman Dr., La Jolla, CA 92093, USA
| | - Mirela Simon
- Department of Neurology, Massachusetts General Hospital, 55 Fruit St., Boston, MA 02114, USA
| | - Douglas Maus
- Department of Neurology, Massachusetts General Hospital, 55 Fruit St., Boston, MA 02114, USA
| | - Jong Woo Lee
- Department of Neurology, Brigham and Women's Hospital, 60 Fenwood Rd., Boston, MA 02115, USA
| | - Brian V Nahed
- Department of Neurosurgery, Massachusetts General Hospital, 55 Fruit St., Boston, MA 02114, USA
| | - Pamela S Jones
- Department of Neurosurgery, Massachusetts General Hospital, 55 Fruit St., Boston, MA 02114, USA
| | - Daniel P Cahill
- Department of Neurosurgery, Massachusetts General Hospital, 55 Fruit St., Boston, MA 02114, USA
| | - Garth Rees Cosgrove
- Department of Neurosurgery, Brigham and Women's Hospital, 60 Fenwood Rd., Boston, MA 02115, USA
| | - Catherine J Chu
- Department of Neurology, Massachusetts General Hospital, 55 Fruit St., Boston, MA 02114, USA
| | - Ziv Williams
- Department of Neurosurgery, Massachusetts General Hospital, 55 Fruit St., Boston, MA 02114, USA
| | - Eric Halgren
- Department of Radiology, University of California, San Diego; 9500 Gilman Dr.; La Jolla, CA 92093, USA
| | - Shadi Dayeh
- Department of Electrical and Computer Engineering, University of California, San Diego; 9500 Gilman Dr., La Jolla, CA 92093, USA
| | - Sydney S Cash
- Department of Neurology, Massachusetts General Hospital, 55 Fruit St., Boston, MA 02114, USA.
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12
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Chvojka J, Kudlacek J, Chang WC, Novak O, Tomaska F, Otahal J, Jefferys JGR, Jiruska P. The role of interictal discharges in ictogenesis - A dynamical perspective. Epilepsy Behav 2021; 121:106591. [PMID: 31806490 DOI: 10.1016/j.yebeh.2019.106591] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 09/23/2019] [Accepted: 09/23/2019] [Indexed: 10/25/2022]
Abstract
Interictal epileptiform discharge (IED) is a traditional hallmark of epileptic tissue that is generated by the synchronous activity of a population of neurons. Interictal epileptiform discharges represent a heterogeneous group of pathological activities that differ in shape, duration, spatiotemporal distribution, underlying cellular and network mechanisms, and their relationship to seizure genesis. The exact role of IEDs in epilepsy is still not well understood, and there remains a persistent dichotomy about the impact on IEDs on seizures. Proseizure, antiseizure, and no impact on ictogenesis have all been described in previous studies. In this article, we review the existing knowledge on the role of interictal discharges in seizure genesis, and we discuss how dynamical approaches to ictogenesis can explain the existing dichotomy about the multifaceted role of IEDs in ictogenesis. This article is part of the Special Issue "NEWroscience 2018".
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Affiliation(s)
- Jan Chvojka
- Department of Physiology, Second Faculty of Medicine, Charles University, Prague, Czech Republic; Department of Developmental Epileptology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic; Department of Circuit Theory, Faculty of Electrical Engineering, Czech Technical University in Prague, Prague, Czech Republic
| | - Jan Kudlacek
- Department of Physiology, Second Faculty of Medicine, Charles University, Prague, Czech Republic; Department of Developmental Epileptology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic; Department of Circuit Theory, Faculty of Electrical Engineering, Czech Technical University in Prague, Prague, Czech Republic
| | - Wei-Chih Chang
- Faculty of Veterinary Medicine and Neuroscience Center, University of Helsinki, Helsinki 00014, Finland
| | - Ondrej Novak
- Department of Physiology, Second Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Filip Tomaska
- Department of Physiology, Second Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Jakub Otahal
- Department of Developmental Epileptology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - John G R Jefferys
- Department of Physiology, Second Faculty of Medicine, Charles University, Prague, Czech Republic; Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, United Kingdom
| | - Premysl Jiruska
- Department of Physiology, Second Faculty of Medicine, Charles University, Prague, Czech Republic; Department of Developmental Epileptology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic.
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Nadalin JK, Eden UT, Han X, Richardson RM, Chu CJ, Kramer MA. Application of a convolutional neural network for fully-automated detection of spike ripples in the scalp electroencephalogram. J Neurosci Methods 2021; 360:109239. [PMID: 34090917 DOI: 10.1016/j.jneumeth.2021.109239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 05/17/2021] [Accepted: 05/30/2021] [Indexed: 10/21/2022]
Abstract
BACKGROUND A reliable biomarker to identify cortical tissue responsible for generating epileptic seizures is required to guide prognosis and treatment in epilepsy. Combined spike ripple events are a promising biomarker for epileptogenic tissue that currently require expert review for accurate identification. This expert review is time consuming and subjective, limiting reproducibility and high-throughput applications. NEW METHOD To address this limitation, we develop a fully-automated method for spike ripple detection. The method consists of a convolutional neural network trained to compute the probability that a spectrogram image contains a spike ripple. RESULTS We validate the proposed spike ripple detector on expert-labeled data and show that this detector accurately separates subjects with low and high seizure risks. COMPARISON WITH EXISTING METHOD The proposed method performs as well as existing methods that require manual validation of candidate spike ripple events. The introduction of a fully automated method reduces subjectivity and increases rigor and reproducibility of this epilepsy biomarker. CONCLUSION We introduce and validate a fully-automated spike ripple detector to support utilization of this epilepsy biomarker in clinical and translational work.
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Affiliation(s)
- Jessica K Nadalin
- Department of Mathematics and Statistics, Boston University, Boston, MA 02215, United States
| | - Uri T Eden
- Department of Mathematics and Statistics, Boston University, Boston, MA 02215, United States; Center for Systems Neuroscience, Boston University, Boston, MA 02215, United States
| | - Xue Han
- Center for Systems Neuroscience, Boston University, Boston, MA 02215, United States; Department of Biomedical Engineering, Boston University, Boston, MA 02215, United States
| | - R Mark Richardson
- Department of Neurosurgery, Massachusetts General Hospital, Boston, MA 02114, United States
| | - Catherine J Chu
- Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, United States
| | - Mark A Kramer
- Department of Mathematics and Statistics, Boston University, Boston, MA 02215, United States; Center for Systems Neuroscience, Boston University, Boston, MA 02215, United States.
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14
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Westin K, Pfeiffer C, Andersen LM, Ruffieux S, Cooray G, Kalaboukhov A, Winkler D, Ingvar M, Schneiderman J, Lundqvist D. Detection of interictal epileptiform discharges: A comparison of on-scalp MEG and conventional MEG measurements. Clin Neurophysiol 2020; 131:1711-1720. [DOI: 10.1016/j.clinph.2020.03.041] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 03/06/2020] [Accepted: 03/30/2020] [Indexed: 10/24/2022]
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15
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Su J, Khoo HM, von Ellenrieder N, Zeng LL, Hu D, Dubeau F, Gotman J. fMRI functional connectivity as an indicator of interictal epileptic discharges. NEUROIMAGE-CLINICAL 2019; 24:102038. [PMID: 31734531 PMCID: PMC6861611 DOI: 10.1016/j.nicl.2019.102038] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 10/02/2019] [Accepted: 10/15/2019] [Indexed: 11/26/2022]
Abstract
Functional connectivity to successful EEG/fMRI response indicates higher IED rates. The results hold when correcting for distance to maximum EEG-fMRI and laterality. Intracranial IED rates correlate with functional connectivity to EEG/fMRI maxima. Results suggest it is feasible to non-invasively infer the brain regions with IEDs.
Objective To explore the relationship between functional connectivity and presence of interictal epileptic discharges (IEDs) in different brain regions in intracranial EEG (iEEG). Methods We studied 38 focal epilepsy patients who underwent simultaneous EEG/fMRI scanning and subsequent intracerebral stereo-EEG investigation. In EEG/fMRI analysis, IEDs with different spatial distributions were considered independent studies and IED-related maximal BOLD responses were evaluated. Studies with iEEG electrodes inside the maximal responses were selected and divided into three groups: Studies with 1. distinct maximal BOLD highly concordant with seizure-onset-zone (SOZ); 2. Moderate maximal BOLD concordant with SOZ; 3. maximal BOLD discordant with SOZ. Using maximal BOLD as seed, its functionally connected zone (FCZ) was determined. IED rates in iEEG channels inside and outside the FCZ were compared in the three groups. The effect of laterality and distance between channels and maximal BOLD, and correlation between functional connectivity values and IED rates were analyzed. Results Thirty-six studies in 25 patients were included. IED rates of intracranial EEG channels inside the FCZ were significantly higher than outside in Group 1 (p = 2.6×10−6) and Group 2 (p = 1.2×10−3) and the inside-outside difference remained after regressing distance and laterality factors. In Group 1, connectivity values were significantly correlated with IED rates in channels inside the FCZ (p < 0.05). Significance Our results indicate a higher probability of finding intracranial IEDs in the FCZ of SOZ-concordant maximal BOLD responses than in other regions, regardless of distance and laterality. In studies with distinct maximal BOLD, connectivity values can partially predict IED rates in intracranial EEG. It is thus feasible to non-invasively delineate brain regions that are likely to have high IED rates.
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Affiliation(s)
- Jianpo Su
- Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada; College of Intelligence Science and Technology, National University of Defense Technology, Changsha, Hunan, China.
| | - Hui Ming Khoo
- Department of Neurosurgery, Osaka University Graduate School of Medicine, Suita, Japan
| | | | - Ling-Li Zeng
- College of Intelligence Science and Technology, National University of Defense Technology, Changsha, Hunan, China
| | - Dewen Hu
- College of Intelligence Science and Technology, National University of Defense Technology, Changsha, Hunan, China
| | - François Dubeau
- Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada
| | - Jean Gotman
- Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada
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16
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Diamond JM, Chapeton JI, Theodore WH, Inati SK, Zaghloul KA. The seizure onset zone drives state-dependent epileptiform activity in susceptible brain regions. Clin Neurophysiol 2019; 130:1628-1641. [PMID: 31325676 DOI: 10.1016/j.clinph.2019.05.032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 04/05/2019] [Accepted: 05/14/2019] [Indexed: 01/14/2023]
Abstract
OBJECTIVE Due to variability in the patterns of propagation of interictal epileptiform discharges (IEDs), qualitative definition of the irritative zone has been challenging. Here, we introduce a quantitative approach toward exploration of the dynamics of IED propagation within the irritative zone. METHODS We examined intracranial EEG (iEEG) in nine participants undergoing invasive monitoring for seizure localization. We used an automated IED detector and a community detection algorithm to identify populations of electrodes exhibiting IED activity that co-occur in time, and to group these electrodes into communities. RESULTS Within our algorithmically-identified communities, IED activity in the seizure onset zone (SOZ) tended to lead IED activity in other functionally coupled brain regions. The tendency of pathological activity to arise in the SOZ, and to spread to non-SOZ tissues, was greater in the asleep state. CONCLUSIONS IED activity, and, by extension, the variability observed between the asleep and awake states, is propagated from a core seizure focus to nearby less pathological brain regions. SIGNIFICANCE Using an unsupervised, computational approach, we show that the spread of IED activity through the epilepsy network varies with physiologic state.
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Affiliation(s)
- Joshua M Diamond
- Surgical Neurology Branch, NINDS, National Institutes of Health, Bethesda, MD 20892, United States
| | - Julio I Chapeton
- Surgical Neurology Branch, NINDS, National Institutes of Health, Bethesda, MD 20892, United States
| | - William H Theodore
- Clinical Epilepsy Section, NINDS, National Institutes of Health, Bethesda, MD 20892, United States
| | - Sara K Inati
- Epilepsy Service and EEG Section, NINDS, National Institutes of Health, Bethesda, MD 20892, United States.
| | - Kareem A Zaghloul
- Surgical Neurology Branch, NINDS, National Institutes of Health, Bethesda, MD 20892, United States.
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17
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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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18
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Farrell JS, Nguyen QA, Soltesz I. Resolving the Micro-Macro Disconnect to Address Core Features of Seizure Networks. Neuron 2019; 101:1016-1028. [PMID: 30897354 PMCID: PMC6430140 DOI: 10.1016/j.neuron.2019.01.043] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 12/14/2018] [Accepted: 01/18/2019] [Indexed: 02/07/2023]
Abstract
Current drug treatments for epilepsy attempt to broadly restrict excitability to mask a symptom, seizures, with little regard for the heterogeneous mechanisms that underlie disease manifestation across individuals. Here, we discuss the need for a more complete view of epilepsy, outlining how key features at the cellular and microcircuit level can significantly impact disease mechanisms that are not captured by the most common methodology to study epilepsy, electroencephalography (EEG). We highlight how major advances in neuroscience tool development now enable multi-scale investigation of fundamental questions to resolve the currently controversial understanding of seizure networks. These findings will provide essential insight into what has emerged as a disconnect between the different levels of investigation and identify new targets and treatment options.
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Affiliation(s)
- Jordan S Farrell
- Department of Neurosurgery, Stanford University, Stanford, CA, USA.
| | - Quynh-Anh Nguyen
- 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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Jacob T, Lillis KP, Wang Z, Swiercz W, Rahmati N, Staley KJ. A Proposed Mechanism for Spontaneous Transitions between Interictal and Ictal Activity. J Neurosci 2019; 39:557-575. [PMID: 30446533 PMCID: PMC6335741 DOI: 10.1523/jneurosci.0719-17.2018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 10/23/2018] [Accepted: 10/31/2018] [Indexed: 11/21/2022] Open
Abstract
Epileptic networks are characterized by two outputs: brief interictal spikes and rarer, more prolonged seizures. Although either output state is readily modeled in silico and induced experimentally, the transition mechanisms are unknown, in part because no models exhibit both output states spontaneously. In silico small-world neural networks were built using single-compartment neurons whose physiological parameters were derived from dual whole-cell recordings of pyramidal cells in organotypic hippocampal slice cultures that were generating spontaneous seizure-like activity. In silico, neurons were connected by abundant local synapses and rare long-distance synapses. Activity-dependent synaptic depression and gradual recovery delimited synchronous activity. Full synaptic recovery engendered interictal population spikes that spread via long-distance synapses. When synaptic recovery was incomplete, postsynaptic neurons required coincident activation of multiple presynaptic terminals to reach firing threshold. Only local connections were sufficiently dense to spread activity under these conditions. This coalesced network activity into traveling waves whose velocity varied with synaptic recovery. Seizures were comprised of sustained traveling waves that were similar to those recorded during experimental and human neocortical seizures. Sustained traveling waves occurred only when wave velocity, network dimensions, and the rate of synaptic recovery enabled wave reentry into previously depressed areas at precisely ictogenic levels of synaptic recovery. Wide-field, cellular-resolution GCamP7b calcium imaging demonstrated similar initial patterns of activation in the hippocampus, although the anatomical distribution of traveling waves of synaptic activation was altered by the pattern of synaptic connectivity in the organotypic hippocampal cultures.SIGNIFICANCE STATEMENT When computerized distributed neural network models are required to generate both features of epileptic networks (i.e., spontaneous interictal population spikes and seizures), the network structure is substantially constrained. These constraints provide important new hypotheses regarding the nature of epileptic networks and mechanisms of seizure onset.
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Affiliation(s)
- Theju Jacob
- Massachusetts General Hospital, Boston, Massachusetts 02114
- Harvard Medical School, Boston, MA 02115
| | - Kyle P Lillis
- Massachusetts General Hospital, Boston, Massachusetts 02114
- Harvard Medical School, Boston, MA 02115
| | - Zemin Wang
- Brigham and Women's Hospital, Boston, MA 02115, and
- Harvard Medical School, Boston, MA 02115
| | - Waldemar Swiercz
- Massachusetts General Hospital, Boston, Massachusetts 02114
- Harvard Medical School, Boston, MA 02115
| | - Negah Rahmati
- Massachusetts General Hospital, Boston, Massachusetts 02114
- Harvard Medical School, Boston, MA 02115
| | - Kevin J Staley
- Massachusetts General Hospital, Boston, Massachusetts 02114,
- Harvard Medical School, Boston, MA 02115
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20
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Fu X, Wang Y, Ge M, Wang D, Gao R, Wang L, Guo J, Liu H. Negative effects of interictal spikes on theta rhythm in human temporal lobe epilepsy. Epilepsy Behav 2018; 87:207-212. [PMID: 30115601 PMCID: PMC6544467 DOI: 10.1016/j.yebeh.2018.07.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2017] [Revised: 03/19/2018] [Accepted: 07/20/2018] [Indexed: 10/28/2022]
Abstract
Interictal spike is a biomarker of epilepsy that can occur frequently between seizures. Its potential effects on brain oscillations, especially on theta rhythm (4-8 Hz) that is related to a variety of cognitive processes, remain controversial. Using local field potentials recorded from patients with temporal lobe epilepsy (TLE), we investigated here the impact of spikes on theta rhythm immediately after spikes and during the prolonged periods (lasting 4-36 s) between adjacent spikes. Local field potentials (LFPs) were recorded in different epileptogenic areas including the anterior hippocampus (aH) and the entorhinal cortex (EC) as well as in the extended propagation pathway. We found that interictal spikes had a significant inhibitory effect on theta rhythm. Power of theta rhythm was reduced immediately after spikes, and the inhibitory effect on theta rhythm might sustain during the prolonged between-spike periods. The inhibitory effect was more severe when the epileptogenic areas involved both the aH and EC compared to that involved only a single structure. These observations suggest that interictal spikes have a significant negative impact on theta rhythm and may thus play a role in theta-related cognition changes in patients with TLE.
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Affiliation(s)
- Xiaoxuan Fu
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, School of Electrical Engineering, Hebei University of Technology, 369#, Tianjin 300130, China
| | - Youhua Wang
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, School of Electrical Engineering, Hebei University of Technology, 369#, Tianjin 300130, China
| | - Manling Ge
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, School of Electrical Engineering, Hebei University of Technology, 369#, Tianjin 300130, China.
| | - Danhong Wang
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Rongguang Gao
- Department of Nuclear Medicine, Fuzhou General Hospital, No. 156, Second West Ring Road, Fuzhou 350025, China
| | - Long Wang
- Liaoyuan Hospital of Traditional Chinese Medicine, Liaoyuan 136200, China
| | - Jundan Guo
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, School of Electrical Engineering, Hebei University of Technology, 369#, Tianjin 300130, China
| | - Hesheng Liu
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA; Institute for Research and Medical Consultations, Imam Abdulahman Bin Faisal University, Dammam, Saudi Arabia.
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21
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Tamilia E, Park EH, Percivati S, Bolton J, Taffoni F, Peters JM, Grant PE, Pearl PL, Madsen JR, Papadelis C. Surgical resection of ripple onset predicts outcome in pediatric epilepsy. Ann Neurol 2018; 84:331-346. [PMID: 30022519 DOI: 10.1002/ana.25295] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 07/05/2018] [Accepted: 07/06/2018] [Indexed: 12/31/2022]
Abstract
OBJECTIVE In patients with medically refractory epilepsy (MRE), interictal ripples (80-250Hz) are observed in large brain areas whose resection may be unnecessary for seizure freedom. This limits their utility as epilepsy biomarkers for surgery. We assessed the spatiotemporal propagation of interictal ripples on intracranial electroencephalography (iEEG) in children with MRE, compared it with the propagation of spikes, identified ripples that initiated propagation (onset-ripples), and evaluated their clinical value as epilepsy biomarkers. METHODS Twenty-seven children who underwent epilepsy surgery were studied. We identified propagation sequences of ripples and spikes across multiple iEEG contacts and calculated each ripple or spike latency from the propagation onset. We classified ripples and spikes into categories (ie, onset, spread, and isolated) based on their spatiotemporal characteristics and correlated their mean rate inside and outside resection with outcome (good outcome, Engel 1 versus poor outcome, Engel≥2). We determined, as onset-zone, spread-zone, and isolated-zone, the areas generating the corresponding ripple or spike category and evaluated the predictive value of their resection. RESULTS We observed ripple propagation in all patients and spike propagation in 25 patients. Mean rate of onset-ripples inside resection predicted the outcome (odds ratio = 5.37; p = 0.02) and correlated with Engel class (rho = -0.55; p = 0.003). Resection of the onset-ripple-zone was associated with good outcome (p = 0.047). No association was found for the spread-ripple-zone, isolated-ripple-zone, or any spike-zone. INTERPRETATION Interictal ripples propagate across iEEG contacts in children with MRE. The association between the onset-ripple-zone resection and good outcome indicates that onset-ripples are promising epilepsy biomarkers, which estimate the epileptogenic tissue better than spread-ripples or onset-spikes. Ann Neurol 2018;84:331-346.
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Affiliation(s)
- Eleonora Tamilia
- Laboratory of Children's Brain Dynamics, Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA.,Fetal-Neonatal Neuroimaging and Developmental Science Center, Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Eun-Hyoung Park
- Division of Epilepsy Surgery, Department of Neurosurgery, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Stefania Percivati
- Laboratory of Children's Brain Dynamics, Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA.,Unit of Biomedical Robotics and Biomicrosystems, Engineering Department, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Jeffrey Bolton
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Fabrizio Taffoni
- Unit of Biomedical Robotics and Biomicrosystems, Engineering Department, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Jurriaan M Peters
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - P Ellen Grant
- Fetal-Neonatal Neuroimaging and Developmental Science Center, Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Phillip L Pearl
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Joseph R Madsen
- Division of Epilepsy Surgery, Department of Neurosurgery, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Christos Papadelis
- Laboratory of Children's Brain Dynamics, Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA.,Fetal-Neonatal Neuroimaging and Developmental Science Center, Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA
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Lillis KP, Staley KJ. Optogenetic dissection of ictogenesis: in search of a targeted anti-epileptic therapy. J Neural Eng 2018; 15:041001. [PMID: 29536948 PMCID: PMC6257979 DOI: 10.1088/1741-2552/aab66a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
For over a century, epileptic seizures have been characterized as a state of pathological, hypersynchronous brain activity. Anti-epileptic therapies have been developed largely based on the dogma that the altered brain rhythms result from an overabundance of glutamatergic activity or insufficient GABAergic inhibition. The most effective drugs in use today act to globally decrease excitation, increase inhibition, or decrease all activity. Unfortunately, such broad alterations to brain activity often lead to impactful side effects such as drowsiness, cognitive impairment, and sleep disruption. Recent advances in optical imaging, optogenetics, and chemogenetics have made it feasible to record and alter neuronal activity with single neuron resolution and genetically directed targeting. The goal of this review it to summarize the usage of these research tools in the study of ictogenesis (seizure generation) and propose a translational pathway by which these studies could result in novel clinical therapies. This manuscript is not intended to serve as an exhaustive list of optogenetic tools nor as a summary of all optogenetic manipulations in epilepsy research. Rather, we will focus on the tools and research aimed at dissecting the basic neuron-level interactions underlying ictogenesis.
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Interneurons and the Ictal Orchestra. Epilepsy Curr 2018; 18:184-186. [DOI: 10.5698/1535-7597.18.3.184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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24
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Janca R, Krsek P, Jezdik P, Cmejla R, Tomasek M, Komarek V, Marusic P, Jiruska P. The Sub-Regional Functional Organization of Neocortical Irritative Epileptic Networks in Pediatric Epilepsy. Front Neurol 2018; 9:184. [PMID: 29628910 PMCID: PMC5876241 DOI: 10.3389/fneur.2018.00184] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 03/09/2018] [Indexed: 11/13/2022] Open
Abstract
Between seizures, irritative network generates frequent brief synchronous activity, which manifests on the EEG as interictal epileptiform discharges (IEDs). Recent insights into the mechanism of IEDs at the microscopic level have demonstrated a high variance in the recruitment of neuronal populations generating IEDs and a high variability in the trajectories through which IEDs propagate across the brain. These phenomena represent one of the major constraints for precise characterization of network organization and for the utilization of IEDs during presurgical evaluations. We have developed a new approach to dissect human neocortical irritative networks and quantify their properties. We have demonstrated that irritative network has modular nature and it is composed of multiple independent sub-regions, each with specific IED propagation trajectories and differing in the extent of IED activity generated. The global activity of the irritative network is determined by long-term and circadian fluctuations in sub-region spatiotemporal properties. Also, the most active sub-region co-localizes with the seizure onset zone in 12/14 cases. This study demonstrates that principles of recruitment variability and propagation are conserved at the macroscopic level and that they determine irritative network properties in humans. Functional stratification of the irritative network increases the diagnostic yield of intracranial investigations with the potential to improve the outcomes of surgical treatment of neocortical epilepsy.
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Affiliation(s)
- Radek Janca
- Department of Circuit Theory, Faculty of Electrical Engineering, Czech Technical University in Prague, Prague, Czechia
| | - Pavel Krsek
- Department of Pediatric Neurology, 2nd Faculty of Medicine, Charles University, Motol University Hospital, Prague, Czechia
| | - Petr Jezdik
- Department of Circuit Theory, Faculty of Electrical Engineering, Czech Technical University in Prague, Prague, Czechia
| | - Roman Cmejla
- Department of Circuit Theory, Faculty of Electrical Engineering, Czech Technical University in Prague, Prague, Czechia
| | - Martin Tomasek
- Department of Neurology, 2nd Faculty of Medicine, Charles University, Motol University Hospital, Prague, Czechia
| | - Vladimir Komarek
- Department of Pediatric Neurology, 2nd Faculty of Medicine, Charles University, Motol University Hospital, Prague, Czechia
| | - Petr Marusic
- Department of Neurology, 2nd Faculty of Medicine, Charles University, Motol University Hospital, Prague, Czechia
| | - Premysl Jiruska
- Department of Developmental Epileptology, Institute of Physiology, The Czech Academy of Sciences, Prague, Czechia
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Qin P, Duncan NW, Chen DYT, Chen CJ, Huang LK, Huang Z, Lin CYE, Wiebking C, Yang CM, Northoff G, Lane TJ. Vascular-metabolic and GABAergic Inhibitory Correlates of Neural Variability Modulation. A Combined fMRI and PET Study. Neuroscience 2018. [PMID: 29530810 DOI: 10.1016/j.neuroscience.2018.02.041] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Neural activity varies continually from moment to moment. Such temporal variability (TV) has been highlighted as a functionally specific brain property playing a fundamental role in cognition. We sought to investigate the mechanisms involved in TV changes between two basic behavioral states, namely having the eyes open (EO) or eyes closed (EC) in vivo in humans. To these ends we acquired BOLD fMRI, ASL, and [18F]-fluoro-deoxyglucose PET in a group of healthy participants (n = 15), along with BOLD fMRI and [18F]-flumazenil PET in a separate group (n = 19). Focusing on an EO- vs EC-sensitive region in the occipital cortex (identified in an independent sample), we show that TV is constrained in the EO condition compared to EC. This reduction is correlated with an increase in energy consumption and with regional GABAA receptor density. This suggests that the modulation of TV by behavioral state involves an increase in overall neural activity that is related to an increased effect from GABAergic inhibition in addition to any excitatory changes. These findings contribute to our understanding of the mechanisms underlying activity variability in the human brain and its control.
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Affiliation(s)
- Pengmin Qin
- Guangdong Key Laboratory of Mental Health and Cognitive Science, South China Normal University, Guangzhou, China; Graduate Institute of Humanities in Medicine, Taipei Medical University, Taipei, Taiwan; Brain and Consciousness Research Centre, Taipei Medical University-Shuang Ho Hospital, New Taipei City, Taiwan; Centre for Studies of Psychological Applications, South China Normal University, Guangzhou, China; School of Psychology, South China Normal University, Guangzhou, China
| | - Niall W Duncan
- Graduate Institute of Humanities in Medicine, Taipei Medical University, Taipei, Taiwan; Brain and Consciousness Research Centre, Taipei Medical University-Shuang Ho Hospital, New Taipei City, Taiwan; Centre for Cognition and Brain Disorders, Hangzhou Normal University, Hangzhou, China.
| | - David Yen-Ting Chen
- Brain and Consciousness Research Centre, Taipei Medical University-Shuang Ho Hospital, New Taipei City, Taiwan; Department of Radiology, Taipei Medical University-Shuang Ho Hospital, New Taipei City, Taiwan
| | - Chi-Jen Chen
- Department of Radiology, Taipei Medical University-Shuang Ho Hospital, New Taipei City, Taiwan
| | - Li-Kai Huang
- Department of Neurology, Taipei Medical University-Shuang Ho Hospital, New Taipei City, Taiwan
| | - Zirui Huang
- Mind, Brain Imaging and Neuroethics Research Unit, Institute of Mental Health Research, University of Ottawa, Ottawa, Canada
| | | | - Christine Wiebking
- Applied Emotion and Motivation Research, Institute for Psychology and Education, Universität Ulm, Ulm, Germany
| | - Che-Ming Yang
- Department of Nuclear Medicine, Shuang Ho Hospital, Taipei Medical University, New Taipei City, Taiwan
| | - Georg Northoff
- Graduate Institute of Humanities in Medicine, Taipei Medical University, Taipei, Taiwan; Brain and Consciousness Research Centre, Taipei Medical University-Shuang Ho Hospital, New Taipei City, Taiwan; Department of Neurology, Taipei Medical University-Shuang Ho Hospital, New Taipei City, Taiwan; University of Ottawa Brain and Mind Research Institute, Centre for Neural Dynamics, Faculty of Medicine, University of Ottawa, Ottawa, Canada; Mental Health Centre, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, China
| | - Timothy J Lane
- Graduate Institute of Humanities in Medicine, Taipei Medical University, Taipei, Taiwan; Brain and Consciousness Research Centre, Taipei Medical University-Shuang Ho Hospital, New Taipei City, Taiwan; Research Center for Mind, Brain, and Learning, National Chengchi University, Taipei, Taiwan.
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Chizhov AV, Amakhin DV, Zaizev AV, Magazanik LG. AMPAR-mediated Interictal Discharges in Neurons of Entorhinal Cortex: Experiment and Model. DOKLADY BIOLOGICAL SCIENCES : PROCEEDINGS OF THE ACADEMY OF SCIENCES OF THE USSR, BIOLOGICAL SCIENCES SECTIONS 2018; 479:47-50. [PMID: 29790025 DOI: 10.1134/s0012496618020011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Indexed: 06/08/2023]
Abstract
The mechanisms of interictal discharges (IID) were studied under the conditions of the 4-aminopyridine model of spontaneous epileptiform activity in surviving rat brain slice preparations. Addition of the agents blocking GABA and NMDA receptors failed to inhibit IID generation in the entorhinal cortex. A mathematical model of IID has been developed on the basis of the excitatory neuron interaction mediated by the AMPA receptor. Short-term synaptic depression and slow afterspike-hyperpolarization are the key factors required to terminate a single IID. The IID shape-determining factors have been identified. The experimental and model IID features correspond to each other.
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Affiliation(s)
- A V Chizhov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia.
- Ioffe Physical Technical Institute, Russian Academy of Sciences, St. Petersburg, Russia.
| | - D V Amakhin
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia
| | - A V Zaizev
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia
| | - L G Magazanik
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia
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27
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Computational model of interictal discharges triggered by interneurons. PLoS One 2017; 12:e0185752. [PMID: 28977038 PMCID: PMC5627938 DOI: 10.1371/journal.pone.0185752] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Accepted: 09/19/2017] [Indexed: 11/19/2022] Open
Abstract
Interictal discharges (IIDs) are abnormal waveforms registered in the periods before or between seizures. IIDs that are initiated by GABAergic interneurons have not been mathematically modeled yet. In the present study, a mathematical model that describes the mechanisms of these discharges is proposed. The model is based on the experimental recordings of IIDs in pyramidal neurons of the rat entorhinal cortex and estimations of synaptic conductances during IIDs. IIDs were induced in cortico-hippocampal slices by applying an extracellular solution with 4-aminopyridine, high potassium, and low magnesium concentrations. Two different types of IIDs initiated by interneurons were observed. The first type of IID (IID1) was pure GABAergic. The second type of IID (IID2) was induced by GABAergic excitation and maintained by recurrent interactions of both GABA- and glutamatergic neuronal populations. The model employed the conductance-based refractory density (CBRD) approach, which accurately approximates the firing rate of a population of similar Hodgkin-Huxley-like neurons. The model of coupled excitatory and inhibitory populations includes AMPA, NMDA, and GABA-receptor-mediated synapses and gap junctions. These neurons receive both arbitrary deterministic input and individual colored Gaussian noise. Both types of IIDs were successfully reproduced in the model by setting two different depolarized levels for GABA-mediated current reversal potential. It was revealed that short-term synaptic depression is a crucial factor in ceasing each of the discharges, and it also determines their durations and frequencies.
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Lenck-Santini PP. Stereotypical activation of hippocampal ensembles during seizures. Brain 2017; 140:2256-2259. [PMID: 29050401 DOI: 10.1093/brain/awx205] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Neumann AR, Raedt R, Steenland HW, Sprengers M, Bzymek K, Navratilova Z, Mesina L, Xie J, Lapointe V, Kloosterman F, Vonck K, Boon PAJM, Soltesz I, McNaughton BL, Luczak A. Involvement of fast-spiking cells in ictal sequences during spontaneous seizures in rats with chronic temporal lobe epilepsy. Brain 2017; 140:2355-2369. [PMID: 29050390 PMCID: PMC6248724 DOI: 10.1093/brain/awx179] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 05/25/2017] [Accepted: 06/08/2017] [Indexed: 11/14/2022] Open
Abstract
See Lenck-Santini (doi:10.1093/awx205) for a scientific commentary on this article. Epileptic seizures represent altered neuronal network dynamics, but the temporal evolution and cellular substrates of the neuronal activity patterns associated with spontaneous seizures are not fully understood. We used simultaneous recordings from multiple neurons in the hippocampus and neocortex of rats with chronic temporal lobe epilepsy to demonstrate that subsets of cells discharge in a highly stereotypical sequential pattern during ictal events, and that these stereotypical patterns were reproducible across consecutive seizures. In contrast to the canonical view that principal cell discharges dominate ictal events, the ictal sequences were predominantly composed of fast-spiking, putative inhibitory neurons, which displayed unusually strong coupling to local field potential even before seizures. The temporal evolution of activity was characterized by unique dynamics where the most correlated neuronal pairs before seizure onset displayed the largest increases in correlation strength during the seizures. These results demonstrate the selective involvement of fast spiking interneurons in structured temporal sequences during spontaneous ictal events in hippocampal and neocortical circuits in experimental models of chronic temporal lobe epilepsy.
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Affiliation(s)
- Adam R Neumann
- Department of Neuroscience, Canadian Centre for Behavioural
Neuroscience, University of Lethbridge, 4401 University Dr W, Lethbridge, AB, T1K 3M4,
Canada
| | - Robrecht Raedt
- Department of Neurology, Ghent University, Gent, Belgium
| | - Hendrik W Steenland
- Department of Neuroscience, Canadian Centre for Behavioural
Neuroscience, University of Lethbridge, 4401 University Dr W, Lethbridge, AB, T1K 3M4,
Canada
| | | | - Katarzyna Bzymek
- Department of Neuroscience, Canadian Centre for Behavioural
Neuroscience, University of Lethbridge, 4401 University Dr W, Lethbridge, AB, T1K 3M4,
Canada
| | - Zaneta Navratilova
- Department of Neuroscience, Canadian Centre for Behavioural
Neuroscience, University of Lethbridge, 4401 University Dr W, Lethbridge, AB, T1K 3M4,
Canada
- Neuro-Electronics Research Flanders, Leuven, Belgium
| | - Lilia Mesina
- Department of Neuroscience, Canadian Centre for Behavioural
Neuroscience, University of Lethbridge, 4401 University Dr W, Lethbridge, AB, T1K 3M4,
Canada
| | - Jeanne Xie
- Department of Neuroscience, Canadian Centre for Behavioural
Neuroscience, University of Lethbridge, 4401 University Dr W, Lethbridge, AB, T1K 3M4,
Canada
| | - Valerie Lapointe
- Department of Neuroscience, Canadian Centre for Behavioural
Neuroscience, University of Lethbridge, 4401 University Dr W, Lethbridge, AB, T1K 3M4,
Canada
| | - Fabian Kloosterman
- Neuro-Electronics Research Flanders, Leuven, Belgium
- VIB, Leuven, Belgium
- Brain and Cognition Research unit, KU Leuven, Leuven, Belgium
| | - Kristl Vonck
- Department of Neurology, Ghent University, Gent, Belgium
| | | | - Ivan Soltesz
- Department of Neurosurgery, and Stanford Neurosciences Institute,
Stanford University, Stanford, CA, USA
| | - Bruce L McNaughton
- Department of Neuroscience, Canadian Centre for Behavioural
Neuroscience, University of Lethbridge, 4401 University Dr W, Lethbridge, AB, T1K 3M4,
Canada
- Department of Neurobiology and Behavior, University of California at
Irvine, Center for the Neurobiology of Learning and Memory, Irvine, CA, USA
| | - Artur Luczak
- Department of Neuroscience, Canadian Centre for Behavioural
Neuroscience, University of Lethbridge, 4401 University Dr W, Lethbridge, AB, T1K 3M4,
Canada
- Department of Neurosurgery, and Stanford Neurosciences Institute,
Stanford University, Stanford, CA, USA
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David LS, Topolnik L. Target-specific alterations in the VIP inhibitory drive to hippocampal GABAergic cells after status epilepticus. Exp Neurol 2017; 292:102-112. [PMID: 28315308 DOI: 10.1016/j.expneurol.2017.03.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 03/08/2017] [Accepted: 03/14/2017] [Indexed: 01/09/2023]
Abstract
Status epilepticus (SE) is associated with complex reorganization of hippocampal circuits involving a significant loss of specific subtypes of GABAergic interneurons. While adaptive circuit plasticity may increase the chances for recruitment of surviving interneurons, the underlying mechanisms remain largely unknown. We studied the alterations in the inhibitory tone received by the hippocampal CA1 oriens/alveus (O/A) interneurons from the vasoactive intestinal peptide (VIP)- and calretinin (CR)-expressing interneurons using the pilocarpine-induced status epilepticus (SE) model of epilepsy. Our data showed that, while the overall density of the VIP/CR-co-expressing interneurons remained preserved, the number of axonal boutons made by these cells within the CA1 O/A was significantly lower after SE. Furthermore, VIP/CR interneurons exhibited significant alterations in their dendritic morphology and passive membrane properties. Subsequently, while all O/A interneuron types, including oriens-lacunosum moleculare (OLM), bistratified (Bis) and basket cells, exhibited decrease in spontaneous inhibitory drive, Bis and basket cells showed a smaller amplitude of light-evoked IPSCs mediated by the selective activation of VIP-positive interneurons. These data point to the target cell-specific changes in the inhibitory tone provided by the VIP cells to O/A interneurons following SE. Given that basket, Bis and OLM cells coordinate different subcellular domains of pyramidal neurons, significant disinhibition of basket and Bis cells along with a previously reported loss of the OLMs may result in a redistribution of inhibition converging onto pyramidal neurons, with a direct impact onto their recruitment to epileptiform network activity and seizure propagation.
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Affiliation(s)
- Linda Suzanne David
- Neuroscience Axis, CHU de Québec Research Center, Department of Biochemistry, Microbiology and Bio-informatics, Laval University, Québec, PQ, Canada
| | - Lisa Topolnik
- Neuroscience Axis, CHU de Québec Research Center, Department of Biochemistry, Microbiology and Bio-informatics, Laval University, Québec, PQ, Canada.
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31
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Tomlinson SB, Bermudez C, Conley C, Brown MW, Porter BE, Marsh ED. Spatiotemporal Mapping of Interictal Spike Propagation: A Novel Methodology Applied to Pediatric Intracranial EEG Recordings. Front Neurol 2016; 7:229. [PMID: 28066315 PMCID: PMC5165024 DOI: 10.3389/fneur.2016.00229] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 11/30/2016] [Indexed: 12/19/2022] Open
Abstract
Synchronized cortical activity is implicated in both normative cognitive functioning and many neurologic disorders. For epilepsy patients with intractable seizures, irregular synchronization within the epileptogenic zone (EZ) is believed to provide the network substrate through which seizures initiate and propagate. Mapping the EZ prior to epilepsy surgery is critical for detecting seizure networks in order to achieve postsurgical seizure control. However, automated techniques for characterizing epileptic networks have yet to gain traction in the clinical setting. Recent advances in signal processing and spike detection have made it possible to examine the spatiotemporal propagation of interictal spike discharges across the epileptic cortex. In this study, we present a novel methodology for detecting, extracting, and visualizing spike propagation and demonstrate its potential utility as a biomarker for the EZ. Eighteen presurgical intracranial EEG recordings were obtained from pediatric patients ultimately experiencing favorable (i.e., seizure-free, n = 9) or unfavorable (i.e., seizure-persistent, n = 9) surgical outcomes. Novel algorithms were applied to extract multichannel spike discharges and visualize their spatiotemporal propagation. Quantitative analysis of spike propagation was performed using trajectory clustering and spatial autocorrelation techniques. Comparison of interictal propagation patterns revealed an increase in trajectory organization (i.e., spatial autocorrelation) among Sz-Free patients compared with Sz-Persist patients. The pathophysiological basis and clinical implications of these findings are considered.
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Affiliation(s)
- Samuel B Tomlinson
- Department of Pediatrics, Division of Child Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, USA; School of Medicine and Dentistry, University of Rochester Medical Center, Rochester, NY, USA
| | - Camilo Bermudez
- Department of Pediatrics, Division of Child Neurology, Children's Hospital of Philadelphia , Philadelphia, PA , USA
| | - Chiara Conley
- Department of Pediatrics, Division of Child Neurology, Children's Hospital of Philadelphia , Philadelphia, PA , USA
| | - Merritt W Brown
- Department of Pediatrics, Division of Child Neurology, Children's Hospital of Philadelphia , Philadelphia, PA , USA
| | - Brenda E Porter
- Department of Neurology and Neurological Science, Stanford School of Medicine , Palo Alto, CA , USA
| | - Eric D Marsh
- Department of Pediatrics, Division of Child Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, USA; Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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Berdichevsky Y, Saponjian Y, Park K, Roach B, Pouliot W, Lu K, Swiercz W, Dudek FE, Staley KJ. Staged anticonvulsant screening for chronic epilepsy. Ann Clin Transl Neurol 2016; 3:908-923. [PMID: 28097203 PMCID: PMC5224819 DOI: 10.1002/acn3.364] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 09/15/2016] [Accepted: 09/15/2016] [Indexed: 01/06/2023] Open
Abstract
OBJECTIVE Current anticonvulsant screening programs are based on seizures evoked in normal animals. One-third of epileptic patients do not respond to the anticonvulsants discovered with these models. We evaluated a tiered program based on chronic epilepsy and spontaneous seizures, with compounds advancing from high-throughput in vitro models to low-throughput in vivo models. METHODS Epileptogenesis in organotypic hippocampal slice cultures was quantified by lactate production and lactate dehydrogenase release into culture media as rapid assays for seizure-like activity and cell death, respectively. Compounds that reduced these biochemical measures were retested with in vitro electrophysiological confirmation (i.e., second stage). The third stage involved crossover testing in the kainate model of chronic epilepsy, with blinded analysis of spontaneous seizures after continuous electrographic recordings. RESULTS We screened 407 compound-concentration combinations. The cyclooxygenase inhibitor, celecoxib, had no effect on seizures evoked in normal brain tissue but demonstrated robust antiseizure activity in all tested models of chronic epilepsy. INTERPRETATION The use of organotypic hippocampal cultures, where epileptogenesis occurs on a compressed time scale, and where seizure-like activity and seizure-induced cell death can be easily quantified with biomarker assays, allowed us to circumvent the throughput limitations of in vivo chronic epilepsy models. Ability to rapidly screen compounds in a chronic model of epilepsy allowed us to find an anticonvulsant that would be missed by screening in acute models.
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Affiliation(s)
- Yevgeny Berdichevsky
- Department of Electrical and Computer Engineering and Bioengineering ProgramLehigh UniversityBethlehemPennsylvania18015
| | - Yero Saponjian
- Department of NeurologyMassachusetts General HospitalBostonMassachusetts02129
- Harvard Medical SchoolBostonMassachusetts02129
| | - Kyung‐Il Park
- Department of NeurologySeoul National University Hospital Healthcare System Gangnam CenterSeoulSouth Korea06236
| | - Bonnie Roach
- Department of NeurosurgeryUniversity of Utah School of MedicineSalt Lake CityUtah84108
| | - Wendy Pouliot
- Department of NeurosurgeryUniversity of Utah School of MedicineSalt Lake CityUtah84108
| | - Kimberly Lu
- Boston University School of MedicineBostonMassachusetts02119
| | - Waldemar Swiercz
- Department of NeurologyMassachusetts General HospitalBostonMassachusetts02129
- Harvard Medical SchoolBostonMassachusetts02129
| | - F. Edward Dudek
- Department of NeurosurgeryUniversity of Utah School of MedicineSalt Lake CityUtah84108
| | - Kevin J. Staley
- Department of NeurologyMassachusetts General HospitalBostonMassachusetts02129
- Harvard Medical SchoolBostonMassachusetts02129
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Bower MR, Kucewicz MT, St Louis EK, Meyer FB, Marsh WR, Stead M, Worrell GA. Reactivation of seizure-related changes to interictal spike shape and synchrony during postseizure sleep in patients. Epilepsia 2016; 58:94-104. [PMID: 27859029 DOI: 10.1111/epi.13614] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/12/2016] [Indexed: 02/05/2023]
Abstract
OBJECTIVE Local field potentials (LFPs) arise from synchronous activation of millions of neurons, producing seemingly consistent waveform shapes and relative synchrony across electrodes. Interictal spikes (IISs) are LFPs associated with epilepsy that are commonly used to guide surgical resection. Recently, changes in neuronal firing patterns observed in the minutes preceding seizure onset were found to be reactivated during postseizure sleep, a process called seizure-related consolidation (SRC), due to similarities with learning-related consolidation. Because IISs arise from summed neural activity, we hypothesized that changes in IIS shape and relative synchrony would be observed in the minutes preceding seizure onset and would be reactivated preferentially during postseizure slow-wave sleep (SWS). METHODS Scalp and intracranial recordings were obtained continuously across multiple days from clinical macroelectrodes implanted in patients undergoing treatment for intractable epilepsy. Data from scalp electrodes were used to stage sleep. Data from intracranial electrodes were used to detect IISs using a previously established algorithm. Partial correlations were computed for sleep and wake periods before and after seizures as a function of correlations observed in the minutes preceding seizures. Magnetic resonance imaging (MRI) and computed tomography (CT) scans were co-registered with electroencephalography (EEG) to determine the location of the seizure-onset zone (SOZ). RESULTS Changes in IIS shape and relative synchrony were observed on a subset of macroelectrodes minutes before seizure onset, and these changes were reactivated preferentially during postseizure SWS. Changes in synchrony were greatest for pairs of electrodes where at least one electrode was located in the SOZ. SIGNIFICANCE These data suggest preseizure changes in neural activity and their subsequent reactivation occur across a broad spatiotemporal scale: from single neurons to LFPs, both within and outside the SOZ. The preferential reactivation of seizure-related changes in IISs during postseizure SWS adds to a growing body of literature suggesting that pathologic neural processes may utilize physiologic mechanisms of synaptic plasticity.
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Affiliation(s)
- Mark R Bower
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, U.S.A.,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, U.S.A.,Mayo Systems Electrophysiology Laboratory, Mayo Clinic, Rochester, Minnesota, U.S.A
| | - Michal T Kucewicz
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, U.S.A.,Mayo Systems Electrophysiology Laboratory, Mayo Clinic, Rochester, Minnesota, U.S.A
| | - Erik K St Louis
- Department of Medicine and Neurology, Sleep and Cognitive Neurophysiology Laboratory and Center for Sleep Medicine, Mayo Clinic, Rochester, Minnesota, U.S.A
| | - Fredric B Meyer
- Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, U.S.A
| | - W Richard Marsh
- Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, U.S.A
| | - Matt Stead
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, U.S.A.,Mayo Systems Electrophysiology Laboratory, Mayo Clinic, Rochester, Minnesota, U.S.A
| | - Gregory A Worrell
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, U.S.A.,Mayo Systems Electrophysiology Laboratory, Mayo Clinic, Rochester, Minnesota, U.S.A
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Bui AD, Alexander A, Soltesz I. Seizing Control: From Current Treatments to Optogenetic Interventions in Epilepsy. Neuroscientist 2016; 23:68-81. [PMID: 26700888 DOI: 10.1177/1073858415619600] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The unpredictability and severity of seizures contribute to the debilitating nature of epilepsy. These factors also render the condition particularly challenging to treat, as an ideal treatment would need to detect and halt the pathological bursts of hyperactivity without disrupting normal brain activity. Optogenetic techniques offer promising tools to study and perhaps eventually treat this episodic disorder by controlling specific brain circuits in epileptic animals with great temporal precision. Here, we briefly review the current treatment options for patients with epilepsy. We then describe the many ways optogenetics has allowed us to untangle the microcircuits involved in seizure activity, and how it has, in some cases, changed our perception of previous theories of seizure generation. Control of seizures with light is no longer a dream, and has been achieved in numerous different animal models of epilepsy. Beyond its application as a seizure suppressor, we highlight another facet of optogenetics in epilepsy, namely the ability to create "on-demand" seizures, as a tool to systematically probe the dynamics of networks during seizure initiation and propagation. Finally, we look into the future to discuss the possibilities and challenges of translating optogenetic techniques to clinical use.
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Affiliation(s)
- Anh D Bui
- 1 Department of Neurosurgery, Stanford University, Stanford, CA, USA.,2 Department of Anatomy and Neurobiology, University of California, Irvine, CA, USA
| | - Allyson Alexander
- 1 Department of Neurosurgery, Stanford University, Stanford, CA, USA
| | - Ivan Soltesz
- 1 Department of Neurosurgery, Stanford University, Stanford, CA, USA
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Mălîia MD, Meritam P, Scherg M, Fabricius M, Rubboli G, Mîndruţă I, Beniczky S. Epileptiform discharge propagation: Analyzing spikes from the onset to the peak. Clin Neurophysiol 2016; 127:2127-33. [DOI: 10.1016/j.clinph.2015.12.021] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 12/22/2015] [Accepted: 12/31/2015] [Indexed: 11/30/2022]
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Bui A, Kim HK, Maroso M, Soltesz I. Microcircuits in Epilepsy: Heterogeneity and Hub Cells in Network Synchronization. Cold Spring Harb Perspect Med 2015; 5:5/11/a022855. [PMID: 26525454 DOI: 10.1101/cshperspect.a022855] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Epilepsy is a complex disorder involving neurological alterations that lead to the pathological development of spontaneous, recurrent seizures. For decades, seizures were thought to be largely repetitive, and had been examined at the macrocircuit level using electrophysiological recordings. However, research mapping the dynamics of large neuronal populations has revealed that seizures are not simply recurrent bursts of hypersynchrony. Instead, it is becoming clear that seizures involve a complex interplay of different neurons and circuits. Herein, we will review studies examining microcircuit changes that may underlie network hyperexcitability, discussing observations from network theory, computational modeling, and optogenetics. We will delve into the idea of hub cells as pathological centers for seizure activity, and will explore optogenetics as a novel avenue to target and treat pathological circuits. Finally, we will conclude with a discussion on future directions in the field.
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Affiliation(s)
- Anh Bui
- Department of Anatomy and Neurobiology, University of California, Irvine, California 92697
| | - Hannah K Kim
- Department of Anatomy and Neurobiology, University of California, Irvine, California 92697
| | - Mattia Maroso
- Department of Anatomy and Neurobiology, University of California, Irvine, California 92697
| | - Ivan Soltesz
- Department of Anatomy and Neurobiology, University of California, Irvine, California 92697
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Vitantonio D, Xu W, Geng X, Wolff BS, Takagaki K, Motamedi GK, Wu JY. Emergence of dominant initiation sites for interictal spikes in rat neocortex. J Neurophysiol 2015; 114:3315-25. [PMID: 26445866 DOI: 10.1152/jn.00471.2014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 10/01/2015] [Indexed: 11/22/2022] Open
Abstract
Neuronal populations with unbalanced inhibition can generate interictal spikes (ISs), where each IS starts from a small initiation site and then spreads activation across a larger area. We used in vivo voltage-sensitive dye imaging to map the initiation site of ISs in rat visual cortex disinhibited by epidural application of bicuculline methiodide. Immediately after the application of bicuculline, the IS initiation sites were widely distributed over the entire disinhibited area. After ∼ 10 min, a small number of sites became "dominant" and initiated the majority of the ISs throughout the course of imaging. Such domination also occurred in cortical slices, which lack long-range connections between the cortex and subcortical structures. This domination of IS initiation sites may allow timing-related plasticity mechanisms to provide a spatial organization where connections projecting outward from the dominant initiation site become strengthened. Understanding the spatiotemporal organization of IS initiation sites may contribute to our understanding of epileptogenesis in its very early stages, because a dominant IS initiation site with strengthened outward connectivity may ultimately develop into a seizure focus.
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Affiliation(s)
- Daniel Vitantonio
- Department of Neuroscience, Georgetown University Medical Center, Washington, District of Columbia; Department of Neurology, Georgetown University Medical Center, Washington, District of Columbia
| | - Weifeng Xu
- Department of Neuroscience, Georgetown University Medical Center, Washington, District of Columbia
| | - Xinling Geng
- Department of Biomedical Engineering, Capital Medical University, Beijing, China
| | - Brian S Wolff
- Georgetown University Medical Center, Interdepartmental Program of Neuroscience, Washington, District of Columbia; and
| | - Kentaroh Takagaki
- Department of Systems Physiology of Learning, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Gholam K Motamedi
- Department of Neurology, Georgetown University Medical Center, Washington, District of Columbia
| | - Jian-young Wu
- Department of Neuroscience, Georgetown University Medical Center, Washington, District of Columbia;
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Human brain slices for epilepsy research: Pitfalls, solutions and future challenges. J Neurosci Methods 2015; 260:221-32. [PMID: 26434706 DOI: 10.1016/j.jneumeth.2015.09.021] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 09/21/2015] [Accepted: 09/23/2015] [Indexed: 12/17/2022]
Abstract
Increasingly, neuroscientists are taking the opportunity to use live human tissue obtained from elective neurosurgical procedures for electrophysiological studies in vitro. Access to this valuable resource permits unique studies into the network dynamics that contribute to the generation of pathological electrical activity in the human epileptic brain. Whilst this approach has provided insights into the mechanistic features of electrophysiological patterns associated with human epilepsy, it is not without technical and methodological challenges. This review outlines the main difficulties associated with working with epileptic human brain slices from the point of collection, through the stages of preparation, storage and recording. Moreover, it outlines the limitations, in terms of the nature of epileptic activity that can be observed in such tissue, in particular, the rarity of spontaneous ictal discharges, we discuss manipulations that can be utilised to induce such activity. In addition to discussing conventional electrophysiological techniques that are routinely employed in epileptic human brain slices, we review how imaging and multielectrode array recordings could provide novel insights into the network dynamics of human epileptogenesis. Acute studies in human brain slices are ultimately limited by the lifetime of the tissue so overcoming this issue provides increased opportunity for information gain. We review the literature with respect to organotypic culture techniques that may hold the key to prolonging the viability of this material. A combination of long-term culture techniques, viral transduction approaches and electrophysiology in human brain slices promotes the possibility of large scale monitoring and manipulation of neuronal activity in epileptic microcircuits.
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Evolution of Network Synchronization during Early Epileptogenesis Parallels Synaptic Circuit Alterations. J Neurosci 2015; 35:9920-34. [PMID: 26156993 DOI: 10.1523/jneurosci.4007-14.2015] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
In secondary epilepsy, a seizure-prone neural network evolves during the latent period between brain injury and the onset of spontaneous seizures. The nature of the evolution is largely unknown, and even its completeness at the onset of seizures has recently been challenged by measures of gradually decreasing intervals between subsequent seizures. Sequential calcium imaging of neuronal activity, in the pyramidal cell layer of mouse hippocampal in vitro preparations, during early post-traumatic epileptogenesis demonstrated rapid increases in the fraction of neurons that participate in interictal activity. This was followed by more gradual increases in the rate at which individual neurons join each developing seizure, the pairwise correlation of neuronal activities as a function of the distance separating the pair, and network-wide measures of functional connectivity. These data support the continued evolution of synaptic connectivity in epileptic networks beyond the latent period: early seizures occur when recurrent excitatory pathways are largely polysynaptic, while ongoing synaptic remodeling after the onset of epilepsy enhances intranetwork connectivity as well as the onset and spread of seizure activity.
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Muldoon SF, Villette V, Tressard T, Malvache A, Reichinnek S, Bartolomei F, Cossart R. GABAergic inhibition shapes interictal dynamics in awake epileptic mice. Brain 2015; 138:2875-90. [PMID: 26280596 DOI: 10.1093/brain/awv227] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 06/22/2015] [Indexed: 12/12/2022] Open
Abstract
Epilepsy is characterized by recurrent seizures and brief, synchronous bursts called interictal spikes that are present in-between seizures and observed as transient events in EEG signals. While GABAergic transmission is known to play an important role in shaping healthy brain activity, the role of inhibition in these pathological epileptic dynamics remains unclear. Examining the microcircuits that participate in interictal spikes is thus an important first step towards addressing this issue, as the function of these transient synchronizations in either promoting or prohibiting seizures is currently under debate. To identify the microcircuits recruited in spontaneous interictal spikes in the absence of any proconvulsive drug or anaesthetic agent, we combine a chronic model of epilepsy with in vivo two-photon calcium imaging and multiunit extracellular recordings to map cellular recruitment within large populations of CA1 neurons in mice free to run on a self-paced treadmill. We show that GABAergic neurons, as opposed to their glutamatergic counterparts, are preferentially recruited during spontaneous interictal activity in the CA1 region of the epileptic mouse hippocampus. Although the specific cellular dynamics of interictal spikes are found to be highly variable, they are consistently associated with the activation of GABAergic neurons, resulting in a perisomatic inhibitory restraint that reduces neuronal spiking in the principal cell layer. Given the role of GABAergic neurons in shaping brain activity during normal cognitive function, their aberrant unbalanced recruitment during these transient events could have important downstream effects with clinical implications.
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Affiliation(s)
- Sarah Feldt Muldoon
- 1 Institut National de la Santé et de la Recherche Médicale Unité 901, 13009 Marseille, France 2 Aix-Marseille Université, Unité Mixte de Recherche S901, 13009 Marseille, France 3 Institut de Neurobiologie de la Méditerranée, 13009 Marseille, France
| | - Vincent Villette
- 1 Institut National de la Santé et de la Recherche Médicale Unité 901, 13009 Marseille, France 2 Aix-Marseille Université, Unité Mixte de Recherche S901, 13009 Marseille, France 3 Institut de Neurobiologie de la Méditerranée, 13009 Marseille, France
| | - Thomas Tressard
- 1 Institut National de la Santé et de la Recherche Médicale Unité 901, 13009 Marseille, France 2 Aix-Marseille Université, Unité Mixte de Recherche S901, 13009 Marseille, France 3 Institut de Neurobiologie de la Méditerranée, 13009 Marseille, France
| | - Arnaud Malvache
- 1 Institut National de la Santé et de la Recherche Médicale Unité 901, 13009 Marseille, France 2 Aix-Marseille Université, Unité Mixte de Recherche S901, 13009 Marseille, France 3 Institut de Neurobiologie de la Méditerranée, 13009 Marseille, France
| | - Susanne Reichinnek
- 1 Institut National de la Santé et de la Recherche Médicale Unité 901, 13009 Marseille, France 2 Aix-Marseille Université, Unité Mixte de Recherche S901, 13009 Marseille, France 3 Institut de Neurobiologie de la Méditerranée, 13009 Marseille, France
| | - Fabrice Bartolomei
- 4 Institut des Neurosciences des Systèmes, Institut National de la Santé et de la Recherche Médicale Unité 1106, 13005 Marseille, France
| | - Rosa Cossart
- 1 Institut National de la Santé et de la Recherche Médicale Unité 901, 13009 Marseille, France 2 Aix-Marseille Université, Unité Mixte de Recherche S901, 13009 Marseille, France 3 Institut de Neurobiologie de la Méditerranée, 13009 Marseille, France
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41
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Basu I, Kudela P, Korzeniewska A, Franaszczuk PJ, Anderson WS. A study of the dynamics of seizure propagation across micro domains in the vicinity of the seizure onset zone. J Neural Eng 2015; 12:046016. [PMID: 26061006 DOI: 10.1088/1741-2560/12/4/046016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE The use of micro-electrode arrays to measure electrical activity from the surface of the brain is increasingly being investigated as a means to improve seizure onset zone (SOZ) localization. In this work, we used a multivariate autoregressive model to determine the evolution of seizure dynamics in the [Formula: see text] Hz high frequency band across micro-domains sampled by such micro-electrode arrays. We showed that a directed transfer function (DTF) can be used to estimate the flow of seizure activity in a set of simulated micro-electrode data with known propagation pattern. APPROACH We used seven complex partial seizures recorded from four patients undergoing intracranial monitoring for surgical evaluation to reconstruct the seizure propagation pattern over sliding windows using a DTF measure. MAIN RESULTS We showed that a DTF can be used to estimate the flow of seizure activity in a set of simulated micro-electrode data with a known propagation pattern. In general, depending on the location of the micro-electrode grid with respect to the clinical SOZ and the time from seizure onset, ictal propagation changed in directional characteristics over a 2-10 s time scale, with gross directionality limited to spatial dimensions of approximately [Formula: see text]. It was also seen that the strongest seizure patterns in the high frequency band and their sources over such micro-domains are more stable over time and across seizures bordering the clinically determined SOZ than inside. SIGNIFICANCE This type of propagation analysis might in future provide an additional tool to epileptologists for characterizing epileptogenic tissue. This will potentially help narrowing down resection zones without compromising essential brain functions as well as provide important information about targeting anti-epileptic stimulation devices.
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Affiliation(s)
- Ishita Basu
- Department of Neurosurgery, Johns Hopkins University, MD, USA
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42
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Hongo Y, Takasu K, Ikegaya Y, Hasegawa M, Sakaguchi G, Ogawa K. Heterogeneous effects of antiepileptic drugs in an in vitro epilepsy model--a functional multineuron calcium imaging study. Eur J Neurosci 2015; 42:1818-29. [PMID: 25967117 DOI: 10.1111/ejn.12945] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 04/28/2015] [Accepted: 05/06/2015] [Indexed: 01/17/2023]
Abstract
Epilepsy is a chronic brain disease characterised by recurrent seizures. Many studies of this disease have focused on local neuronal activity, such as local field potentials in the brain. In addition, several recent studies have elucidated the collective behavior of individual neurons in a neuronal network that emits epileptic activity. However, little is known about the effects of antiepileptic drugs on neuronal networks during seizure-like events (SLEs) at single-cell resolution. Using functional multineuron Ca(2+) imaging (fMCI), we monitored the activities of multiple neurons in the rat hippocampal CA1 region on treatment with the proconvulsant bicuculline under Mg(2+) -free conditions. Bicuculline induced recurrent synchronous Ca(2+) influx, and the events were correlated with SLEs. Other proconvulsants, such as 4-aminopyridine, pentetrazol, and pilocarpine, also induced synchronous Ca(2+) influx. We found that the antiepileptic drugs phenytoin, flupirtine, and ethosuximide, which have different mechanisms of action, exerted heterogeneous effects on bicuculline-induced synchronous Ca(2+) influx. Phenytoin and flupirtine significantly decreased the peak, the amount of Ca(2+) influx and the duration of synchronous events in parallel with the duration of SLEs, whereas they did not abolish the synchronous events themselves. Ethosuximide increased the duration of synchronous Ca(2+) influx and SLEs. Furthermore, the magnitude of the inhibitory effect of phenytoin on the peak synchronous Ca(2+) influx level differed according to the peak amplitude of the synchronous event in each individual cell. Evaluation of the collective behavior of individual neurons by fMCI seems to be a powerful tool for elucidating the profiles of antiepileptic drugs.
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Affiliation(s)
- Yoshie Hongo
- Pain & Neuroscience, Discovery Research Laboratory for Core Therapeutic Areas, Shionogi Co. Ltd., 1-1 Futaba-cho 3-chome, Toyonaka, Osaka, 561-0825, Japan
| | - Keiko Takasu
- Pain & Neuroscience, Discovery Research Laboratory for Core Therapeutic Areas, Shionogi Co. Ltd., 1-1 Futaba-cho 3-chome, Toyonaka, Osaka, 561-0825, Japan
| | - Yuji Ikegaya
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, University of Tokyo, Bunkyo-ku, Tokyo, Japan.,Center for Information and Neural Networks, Suita City, Osaka, Japan
| | - Minoru Hasegawa
- Pain & Neuroscience, Discovery Research Laboratory for Core Therapeutic Areas, Shionogi Co. Ltd., 1-1 Futaba-cho 3-chome, Toyonaka, Osaka, 561-0825, Japan
| | - Gaku Sakaguchi
- Pain & Neuroscience, Discovery Research Laboratory for Core Therapeutic Areas, Shionogi Co. Ltd., 1-1 Futaba-cho 3-chome, Toyonaka, Osaka, 561-0825, Japan
| | - Koichi Ogawa
- Pain & Neuroscience, Discovery Research Laboratory for Core Therapeutic Areas, Shionogi Co. Ltd., 1-1 Futaba-cho 3-chome, Toyonaka, Osaka, 561-0825, Japan
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Gee JM, Gibbons MB, Taheri M, Palumbos S, Morris SC, Smeal RM, Flynn KF, Economo MN, Cizek CG, Capecchi MR, Tvrdik P, Wilcox KS, White JA. Imaging activity in astrocytes and neurons with genetically encoded calcium indicators following in utero electroporation. Front Mol Neurosci 2015; 8:10. [PMID: 25926768 PMCID: PMC4397926 DOI: 10.3389/fnmol.2015.00010] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2015] [Accepted: 03/23/2015] [Indexed: 11/13/2022] Open
Abstract
Complex interactions between networks of astrocytes and neurons are beginning to be appreciated, but remain poorly understood. Transgenic mice expressing fluorescent protein reporters of cellular activity, such as the GCaMP family of genetically encoded calcium indicators (GECIs), have been used to explore network behavior. However, in some cases, it may be desirable to use long-established rat models that closely mimic particular aspects of human conditions such as Parkinson's disease and the development of epilepsy following status epilepticus. Methods for expressing reporter proteins in the rat brain are relatively limited. Transgenic rat technologies exist but are fairly immature. Viral-mediated expression is robust but unstable, requires invasive injections, and only works well for fairly small genes (<5 kb). In utero electroporation (IUE) offers a valuable alternative. IUE is a proven method for transfecting populations of astrocytes and neurons in the rat brain without the strict limitations on transgene size. We built a toolset of IUE plasmids carrying GCaMP variants 3, 6s, or 6f driven by CAG and targeted to the cytosol or the plasma membrane. Because low baseline fluorescence of GCaMP can hinder identification of transfected cells, we included the option of co-expressing a cytosolic tdTomato protein. A binary system consisting of a plasmid carrying a piggyBac inverted terminal repeat (ITR)-flanked CAG-GCaMP-IRES-tdTomato cassette and a separate plasmid encoding for expression of piggyBac transposase was employed to stably express GCaMP and tdTomato. The plasmids were co-electroporated on embryonic days 13.5-14.5 and astrocytic and neuronal activity was subsequently imaged in acute or cultured brain slices prepared from the cortex or hippocampus. Large spontaneous transients were detected in slices obtained from rats of varying ages up to 127 days. In this report, we demonstrate the utility of this toolset for interrogating astrocytic and neuronal activity in the rat brain.
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Affiliation(s)
- J Michael Gee
- Neuronal Dynamics Laboratory, Department of Bioengineering, University of Utah Salt Lake City, UT, USA ; MD-PhD Program, University of Utah Salt Lake City, UT, USA
| | - Meredith B Gibbons
- Glial-Neuronal Interactions in Epilepsy Laboratory, Department of Pharmacology and Toxicology, University of Utah Salt Lake City, UT, USA ; Interdepartmental Program in Neuroscience, University of Utah Salt Lake City, UT, USA
| | - Marsa Taheri
- Neuronal Dynamics Laboratory, Department of Bioengineering, University of Utah Salt Lake City, UT, USA
| | - Sierra Palumbos
- Mario Capecchi Laboratory, Department of Human Genetics, University of Utah Salt Lake City, UT, USA
| | - S Craig Morris
- Neuronal Dynamics Laboratory, Department of Bioengineering, University of Utah Salt Lake City, UT, USA ; Mario Capecchi Laboratory, Department of Human Genetics, University of Utah Salt Lake City, UT, USA
| | - Roy M Smeal
- Glial-Neuronal Interactions in Epilepsy Laboratory, Department of Pharmacology and Toxicology, University of Utah Salt Lake City, UT, USA
| | - Katherine F Flynn
- Glial-Neuronal Interactions in Epilepsy Laboratory, Department of Pharmacology and Toxicology, University of Utah Salt Lake City, UT, USA
| | - Michael N Economo
- Neuronal Dynamics Laboratory, Department of Bioengineering, University of Utah Salt Lake City, UT, USA
| | - Christian G Cizek
- Neuronal Dynamics Laboratory, Department of Bioengineering, University of Utah Salt Lake City, UT, USA ; Mario Capecchi Laboratory, Department of Human Genetics, University of Utah Salt Lake City, UT, USA
| | - Mario R Capecchi
- Mario Capecchi Laboratory, Department of Human Genetics, University of Utah Salt Lake City, UT, USA ; Department of Human Genetics, Howard Hughes Medical Institute, University of Utah Salt Lake City, UT, USA
| | - Petr Tvrdik
- Mario Capecchi Laboratory, Department of Human Genetics, University of Utah Salt Lake City, UT, USA
| | - Karen S Wilcox
- Glial-Neuronal Interactions in Epilepsy Laboratory, Department of Pharmacology and Toxicology, University of Utah Salt Lake City, UT, USA
| | - John A White
- Neuronal Dynamics Laboratory, Department of Bioengineering, University of Utah Salt Lake City, UT, USA
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Huberfeld G, Blauwblomme T, Miles R. Hippocampus and epilepsy: Findings from human tissues. Rev Neurol (Paris) 2015; 171:236-51. [PMID: 25724711 PMCID: PMC4409112 DOI: 10.1016/j.neurol.2015.01.563] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 01/20/2015] [Indexed: 11/18/2022]
Abstract
Surgical removal of the epileptogenic zone provides an effective therapy for several focal epileptic syndromes. This surgery offers the opportunity to study pathological activity in living human tissue for pharmacoresistant partial epilepsy syndromes including temporal lobe epilepsies with hippocampal sclerosis, cortical dysplasias, epilepsies associated with tumors and developmental malformations. Slices of tissue from patients with these syndromes retain functional neuronal networks and may generate epileptic activities. The properties of cells in this tissue may not be greatly changed, but excitatory synaptic transmission is often enhanced and GABAergic inhibition is preserved. Typically epileptic activity is not generated spontaneously by the neocortex, whether dysplastic or not, but can be induced by convulsants. The initiation of ictal discharges in the neocortex depends on both GABAergic signaling and increased extracellular potassium. In contrast, a spontaneous interictal-like activity is generated by tissues from patients with temporal lobe epilepsies associated with hippocampal sclerosis. This activity is initiated, not in the hippocampus but in the subiculum, an output region, which projects to the entorhinal cortex. Interictal events seem to be triggered by GABAergic cells, which paradoxically excite about 20% of subicular pyramidal cells while simultaneously inhibiting the majority. Interictal discharges thus depend on both GABAergic and glutamatergic signaling. The depolarizing effects of GABA depend on a pathological elevation in levels of chloride in some subicular cells, similar to those of developmentally immature cells. Such defect is caused by a perturbed expression of the cotransporters regulating intracellular chloride concentration, the importer NKCC1 and the extruder KCC2. Blockade of NKCC1 actions by the diuretic bumetanide restores intracellular chloride and thus hyperpolarizing GABAergic actions and consequently suppressing interictal activity.
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Affiliation(s)
- G Huberfeld
- Département de neurophysiologie, Sorbonne universités, UPMC - université Paris 06, UPMC, CHU de la Pitié-Salpêtrière, 47-83, boulevard de l'Hôpital, 75013 Paris, France; INSERM Unit U1129 Infantile Epilepsies and Brain Plasticity, University Paris Descartes, Sorbonne Paris Cité, CEA, 12, rue de l'École-de-Médecine, 75006 Paris, France.
| | - T Blauwblomme
- INSERM Unit U1129 Infantile Epilepsies and Brain Plasticity, University Paris Descartes, Sorbonne Paris Cité, CEA, 12, rue de l'École-de-Médecine, 75006 Paris, France; Neurosurgery Department, Necker-Enfants Malades Hospital, University Paris Descartes, PRES Sorbonne Paris Cité, 12, rue de l'École-de-Médecine, 75006 Paris, France
| | - R Miles
- Inserm U1127, CNRS UMR7225, Sorbonne universités, UPMC - université Paris 6 UMR S1127, Institut du cerveau et de la moelle épinière, 47, boulevard de l'Hôpital, 75013 Paris, France
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45
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Bagić A, Ebersole JS. Does MEG/MSI dipole variability mean unreliability? Clin Neurophysiol 2015; 126:209-11. [DOI: 10.1016/j.clinph.2014.01.037] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 01/20/2014] [Accepted: 01/23/2014] [Indexed: 11/28/2022]
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Alvarado-Rojas C, Huberfeld G, Baulac M, Clemenceau S, Charpier S, Miles R, de la Prida LM, Le Van Quyen M. Different mechanisms of ripple-like oscillations in the human epileptic subiculum. Ann Neurol 2014; 77:281-90. [PMID: 25448920 DOI: 10.1002/ana.24324] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Revised: 11/10/2014] [Accepted: 11/21/2014] [Indexed: 02/06/2023]
Abstract
OBJECTIVE Transient high-frequency oscillations (HFOs; 150-600Hz) in local field potentials generated by human hippocampal and parahippocampal areas have been related to both physiological and pathological processes. The cellular basis and effects of normal and abnormal forms of HFOs have been controversial. This lack of agreement is clinically significant, because HFOs may be good markers of epileptogenic areas. Better defining the neuronal correlate of specific HFO frequency bands could improve electroencephalographic analyses made before epilepsy surgery. METHODS Here, we recorded HFOs in slices of the subiculum prepared from human hippocampal tissue resected for treatment of pharmacoresistant epilepsy. With combined intra- or juxtacellular and extracellular recordings, we examined the cellular correlates of interictal and ictal HFO events. RESULTS HFOs occurred spontaneously in extracellular field potentials during interictal discharges (IIDs) and also during pharmacologically induced preictal discharges (PIDs) preceding ictal-like events. Many of these events included frequencies >250Hz and so might be considered pathological, but a significant proportion were spectrally similar to physiological ripples (150-250Hz). We found that IID ripples were associated with rhythmic γ-aminobutyric acidergic and glutamatergic synaptic potentials with moderate neuronal firing. In contrast, PID ripples were associated with depolarizing synaptic inputs frequently reaching the threshold for bursting in most pyramidal cells. INTERPRETATION Our data suggest that IID and PID ripple-like oscillations (150-250Hz) in human epileptic hippocampus are associated with 2 distinct population activities that rely on different cellular and synaptic mechanisms. Thus, the ripple band could not help to disambiguate the underlying cellular processes.
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Affiliation(s)
- Catalina Alvarado-Rojas
- Brain and Spine Institute, Pitié-Salpêtrière Hospital, Paris, France; Pierre and Marie Curie University, Paris
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Peret A, Christie LA, Ouedraogo DW, Gorlewicz A, Epsztein J, Mulle C, Crépel V. Contribution of aberrant GluK2-containing kainate receptors to chronic seizures in temporal lobe epilepsy. Cell Rep 2014; 8:347-54. [PMID: 25043179 DOI: 10.1016/j.celrep.2014.06.032] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 05/08/2014] [Accepted: 06/19/2014] [Indexed: 02/01/2023] Open
Abstract
Kainate is a potent neurotoxin known to induce acute seizures. However, whether kainate receptors (KARs) play any role in the pathophysiology of temporal lobe epilepsy (TLE) is not known. In TLE, recurrent mossy fiber (rMF) axons form abnormal excitatory synapses onto other dentate granule cells that operate via KARs. The present study explores the pathophysiological implications of KARs in generating recurrent seizures in chronic epilepsy. In an in vitro model of TLE, seizure-like activity was minimized in mice lacking the GluK2 subunit, which is a main component of aberrant synaptic KARs at rMF synapses. In vivo, the frequency of interictal spikes and ictal discharges was strongly reduced in GluK2(-/-) mice or in the presence of a GluK2/GluK5 receptor antagonist. Our data show that aberrant GluK2-containing KARs play a major role in the chronic seizures that characterize TLE and thus constitute a promising antiepileptic target.
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Affiliation(s)
- Angélique Peret
- INSERM, INMED, U901, 13009 Marseille, France; Aix-Marseille Université, UMR 901, 13009 Marseille, France
| | - Louisa A Christie
- INSERM, INMED, U901, 13009 Marseille, France; Aix-Marseille Université, UMR 901, 13009 Marseille, France
| | - David W Ouedraogo
- INSERM, INMED, U901, 13009 Marseille, France; Aix-Marseille Université, UMR 901, 13009 Marseille, France
| | - Adam Gorlewicz
- Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, University of Bordeaux, 33000 Bordeaux, France
| | - Jérôme Epsztein
- INSERM, INMED, U901, 13009 Marseille, France; Aix-Marseille Université, UMR 901, 13009 Marseille, France
| | - Christophe Mulle
- Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, University of Bordeaux, 33000 Bordeaux, France
| | - Valérie Crépel
- INSERM, INMED, U901, 13009 Marseille, France; Aix-Marseille Université, UMR 901, 13009 Marseille, France.
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Wu Y, Liu D, Song Z. Neuronal networks and energy bursts in epilepsy. Neuroscience 2014; 287:175-86. [PMID: 24993475 DOI: 10.1016/j.neuroscience.2014.06.046] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Revised: 06/16/2014] [Accepted: 06/17/2014] [Indexed: 11/16/2022]
Abstract
Epilepsy can be defined as the abnormal activities of neurons. The occurrence, propagation and termination of epileptic seizures rely on the networks of neuronal cells that are connected through both synaptic- and non-synaptic interactions. These complicated interactions contain the modified functions of normal neurons and glias as well as the mediation of excitatory and inhibitory mechanisms with feedback homeostasis. Numerous spread patterns are detected in disparate networks of ictal activities. The cortical-thalamic-cortical loop is present during a general spike wave seizure. The thalamic reticular nucleus (nRT) is the major inhibitory input traversing the region, and the dentate gyrus (DG) controls CA3 excitability. The imbalance between γ-aminobutyric acid (GABA)-ergic inhibition and glutamatergic excitation is the main disorder in epilepsy. Adjustable negative feedback that mediates both inhibitory and excitatory components affects neuronal networks through neurotransmission fluctuation, receptor and transmitter signaling, and through concomitant influences on ion concentrations and field effects. Within a limited dynamic range, neurons slowly adapt to input levels and have a high sensitivity to synaptic changes. The stability of the adapting network depends on the ratio of the adaptation rates of both the excitatory and inhibitory populations. Thus, therapeutic strategies with multiple effects on seizures are required for the treatment of epilepsy, and the therapeutic functions on networks are reviewed here. Based on the high-energy burst theory of epileptic activity, we propose a potential antiepileptic therapeutic strategy to transfer the high energy and extra electricity out of the foci.
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Affiliation(s)
- Y Wu
- The Neurology Department of Third Xiangya Hospital, Medical School of Central South University, Changsha, China
| | - D Liu
- The Neurology Department of Third Xiangya Hospital, Medical School of Central South University, Changsha, China
| | - Z Song
- The Neurology Department of Third Xiangya Hospital, Medical School of Central South University, Changsha, China.
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Extracellular calcium controls the expression of two different forms of ripple-like hippocampal oscillations. J Neurosci 2014; 34:2989-3004. [PMID: 24553939 DOI: 10.1523/jneurosci.2826-13.2014] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Hippocampal high-frequency oscillations (HFOs) are prominent in physiological and pathological conditions. During physiological ripples (100-200 Hz), few pyramidal cells fire together coordinated by rhythmic inhibitory potentials. In the epileptic hippocampus, fast ripples (>200 Hz) reflect population spikes (PSs) from clusters of bursting cells, but HFOs in the ripple and the fast ripple range are vastly intermixed. What is the meaning of this frequency range? What determines the expression of different HFOs? Here, we used different concentrations of Ca(2+) in a physiological range (1-3 mM) to record local field potentials and single cells in hippocampal slices from normal rats. Surprisingly, we found that this sole manipulation results in the emergence of two forms of HFOs reminiscent of ripples and fast ripples recorded in vivo from normal and epileptic rats, respectively. We scrutinized the cellular correlates and mechanisms underlying the emergence of these two forms of HFOs by combining multisite, single-cell and paired-cell recordings in slices prepared from a rat reporter line that facilitates identification of GABAergic cells. We found a major effect of extracellular Ca(2+) in modulating intrinsic excitability and disynaptic inhibition, two critical factors shaping network dynamics. Moreover, locally modulating the extracellular Ca(2+) concentration in an in vivo environment had a similar effect on disynaptic inhibition, pyramidal cell excitability, and ripple dynamics. Therefore, the HFO frequency band reflects a range of firing dynamics of hippocampal networks.
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Cossart R. Operational hub cells: a morpho-physiologically diverse class of GABAergic neurons united by a common function. Curr Opin Neurobiol 2013; 26:51-6. [PMID: 24650504 DOI: 10.1016/j.conb.2013.12.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 11/06/2013] [Accepted: 12/03/2013] [Indexed: 11/30/2022]
Abstract
GABAergic microcircuits structure the activation of neuronal ensembles that support most cortical computations. Because of the heterogeneous nature of the GABAergic cell community, a full understanding of structure-function relationships in these microcircuits may be hampered by a reductionist approach that consists of classifying them according to an exhaustive collection of parameters. It therefore could be beneficial to our understanding of these complex cells to also consider other approaches. Thus, graph theory has recently taught us that biological networks often include hub nodes that are essential for information flow, and ensuing experimental evidence has demonstrated the existence of 'operational' hub neurons. So far, only GABAergic neurons have been identified as 'operational hubs', further emphasizing their critical function in controlling cortical network dynamics.
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Affiliation(s)
- Rosa Cossart
- INMED, INSERM U901, Aix-Marseille Université, Parc Scientifique de Luminy, BP.13, 13273 Marseille cedex 9, France.
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