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Shi W, Shaw D, Walsh KG, Han X, Eden UT, Richardson RM, Gliske SV, Jacobs J, Brinkmann BH, Worrell GA, Stacey WC, Frauscher B, Thomas J, Kramer MA, Chu CJ. Spike ripples localize the epileptogenic zone best: an international intracranial study. Brain 2024; 147:2496-2506. [PMID: 38325327 PMCID: PMC11224608 DOI: 10.1093/brain/awae037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 12/10/2023] [Accepted: 01/19/2024] [Indexed: 02/09/2024] Open
Abstract
We evaluated whether spike ripples, the combination of epileptiform spikes and ripples, provide a reliable and improved biomarker for the epileptogenic zone compared with other leading interictal biomarkers in a multicentre, international study. We first validated an automated spike ripple detector on intracranial EEG recordings. We then applied this detector to subjects from four centres who subsequently underwent surgical resection with known 1-year outcomes. We evaluated the spike ripple rate in subjects cured after resection [International League Against Epilepsy Class 1 outcome (ILAE 1)] and those with persistent seizures (ILAE 2-6) across sites and recording types. We also evaluated available interictal biomarkers: spike, spike-gamma, wideband high frequency oscillation (HFO, 80-500 Hz), ripple (80-250 Hz) and fast ripple (250-500 Hz) rates using previously validated automated detectors. The proportion of resected events was computed and compared across subject outcomes and biomarkers. Overall, 109 subjects were included. Most spike ripples were removed in subjects with ILAE 1 outcome (P < 0.001), and this was qualitatively observed across all sites and for depth and subdural electrodes (P < 0.001 and P < 0.001, respectively). Among ILAE 1 subjects, the mean spike ripple rate was higher in the resected volume (0.66/min) than in the non-removed tissue (0.08/min, P < 0.001). A higher proportion of spike ripples were removed in subjects with ILAE 1 outcomes compared with ILAE 2-6 outcomes (P = 0.06). Among ILAE 1 subjects, the proportion of spike ripples removed was higher than the proportion of spikes (P < 0.001), spike-gamma (P < 0.001), wideband HFOs (P < 0.001), ripples (P = 0.009) and fast ripples (P = 0.009) removed. At the individual level, more subjects with ILAE 1 outcomes had the majority of spike ripples removed (79%, 38/48) than spikes (69%, P = 0.12), spike-gamma (69%, P = 0.12), wideband HFOs (63%, P = 0.03), ripples (45%, P = 0.01) or fast ripples (36%, P < 0.001) removed. Thus, in this large, multicentre cohort, when surgical resection was successful, the majority of spike ripples were removed. Furthermore, automatically detected spike ripples localize the epileptogenic tissue better than spikes, spike-gamma, wideband HFOs, ripples and fast ripples.
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Affiliation(s)
- Wen Shi
- Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Dana Shaw
- Graduate Program in Neuroscience, Boston University, Boston, MA 02215, USA
| | - Katherine G Walsh
- Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Xue Han
- Center for Systems Neuroscience, Boston University, Boston, MA 02215, USA
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
| | - Uri T Eden
- Center for Systems Neuroscience, Boston University, Boston, MA 02215, USA
- Department of Mathematics and Statistics, Boston University, Boston, MA 02215, USA
| | - Robert M Richardson
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
- Department of Neurosurgery, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Stephen V Gliske
- Department of Neurosurgery, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Julia Jacobs
- Department of Neuropediatrics and Muscle Disorders, Medical Center, University of Freiburg, Freiburg 79106, Germany
- Department of Paediatrics, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
- Department of Neuroscience, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
- Hotchkiss Brain Institute and Alberta Children’s Hospital Research Institute, University of Calgary, Calgary T2N 1N4, AB, Canada
| | - Benjamin H Brinkmann
- Bioelectronics Neurophysiology and Engineering Lab, Mayo Clinic, Rochester, MN 55905, USA
| | - Gregory A Worrell
- Bioelectronics Neurophysiology and Engineering Lab, Mayo Clinic, Rochester, MN 55905, USA
| | - William C Stacey
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Birgit Frauscher
- Analytical Neurophysiology Lab, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC H3A 0G4, Canada
- Analytical Neurophysiology Lab, Department of Neurology, Duke University Medical Center, Durham, NC 27710, USA
- Department of Biomedical Engineering, Duke Pratt School of Engineering, Durham, NC 27708, USA
| | - John Thomas
- Analytical Neurophysiology Lab, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC H3A 0G4, Canada
| | - Mark A Kramer
- Center for Systems Neuroscience, Boston University, Boston, MA 02215, USA
- Department of Mathematics and Statistics, Boston University, Boston, MA 02215, USA
| | - Catherine J Chu
- Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
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Buzsáki G, Freund T, Fricker D, Gulyás AI, Huberfeld G, Menendez de la Prida L, Poncer JC, Tóth K, Traub R, Wittner L, Wong RKS. In Memoriam: Richard Miles: Neuroscience network has lost a key synapse. J Physiol 2024; 602:1863-1874. [PMID: 38598307 DOI: 10.1113/jp286319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Accepted: 03/14/2024] [Indexed: 04/12/2024] Open
Affiliation(s)
- György Buzsáki
- NYU Neuroscience Institute, New York University, Langone Medical Center, New York, New York, USA
| | - Tamás Freund
- Institute of Experimental Medicine, Hungarian Research Network (HUN-REN), Budapest, Hungary
| | - Desdemona Fricker
- Integrative Neuroscience and Cognition Center, Université Paris Cité, CNRS UMR-S 8002, Paris, France
| | - Attila I Gulyás
- Institute of Experimental Medicine, Hungarian Research Network (HUN-REN), Budapest, Hungary
| | - Gilles Huberfeld
- Institute of Psychiatry and Neuroscience of Paris, Inserm, Université Paris Cité, UMR-S 1266, Neuronal Signaling in Epilepsy and Glioma, Paris, France
- Department of Neurology, Hôpital Fondation Adolphe de Rothschild, Paris, France
| | | | | | - Katalin Tóth
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Canada
| | - Roger Traub
- Exploratory Research, IBM T.J. Watson Research Center, Department of Neuroscience, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Lucia Wittner
- Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Research Network, Budapest, Hungary
| | - Robert K S Wong
- Department of Physiology and Pharmacology, State University of New York, Downstate Medical Center, Brooklyn, New York, USA
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Kalogeropoulos K, Psarropoulou C. Immature Status Epilepticus Alters the Temporal Relationship between Hippocampal Interictal Epileptiform Discharges and High-frequency Oscillations. Neuroscience 2024; 543:108-120. [PMID: 38401712 DOI: 10.1016/j.neuroscience.2024.02.019] [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: 12/15/2023] [Revised: 02/16/2024] [Accepted: 02/20/2024] [Indexed: 02/26/2024]
Abstract
The aim was to investigate the long-term effects of a single episode of immature Status Epilepticus (SE) on the excitability of the septal and temporal hippocampus in vitro, by studying the relationship between interictal-like epileptiform discharges (IEDs) and high-frequency oscillations (HFOs; Ripples, Rs and Fast Ripples, FRs). A pentylenetetrazol-induced Status Epilepticus-(SE)-like generalized seizure was induced at postnatal day 20 in 22 male and female juvenile rats, sacrificed >40 days later to prepare hippocampal slices. Spontaneous IEDs induced by Mg2+-free ACSF were recorded from the CA3 area of temporal (T) or septal (S) slices. Recordings were band-pass filtered off-line revealing Rs and FRs and a series of measurements were conducted, with mean values compared with those obtained from age-matched controls (CTRs). In CTR S (vs T) slices, we recorded longer R & FR durations, a longer HFO-IED temporal overlap, higher FR peak power and more frequent FR initiation preceding IEDs (% events). Post-SE, in T slices all types of events duration (IED, R, FR) and the time lag between their onsets (R-IED, FR-IED, R-FR) increased, while FR/R peak power decreased; in S slices, the IED 1st population spike and the FR amplitudes, the R and FR peak power and the (percent) events where Rs or FRs preceded IEDs all decreased. The CA3 IED-HFO relationship offers insights to the septal-to-temporal synchronization patterns; its post-juvenile-SE changes indicate permanent modifications in the septotemporal excitability gradient. Moreover, these findings are in line to region-specific regulation of various currents post-SE, as reported in literature.
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Affiliation(s)
- Konstantinos Kalogeropoulos
- Laboratory of Animal and Human Physiology, Department of Biological Applications and Technology, Faculty of Health Sciences, University of Ioannina, 45110, Greece.
| | - Caterina Psarropoulou
- Laboratory of Animal and Human Physiology, Department of Biological Applications and Technology, Faculty of Health Sciences, University of Ioannina, 45110, Greece.
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Furukawa R, Yoshikawa T, Murakami S, Tateno T. A piezoelectric micromachined ultrasound transducer combined with recording electrodes for acute brain preparations in vitro. J Neurosci Methods 2024; 403:110048. [PMID: 38151186 DOI: 10.1016/j.jneumeth.2023.110048] [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: 11/16/2023] [Revised: 12/11/2023] [Accepted: 12/21/2023] [Indexed: 12/29/2023]
Abstract
BACKGROUND Ultrasound stimulation is used to noninvasively stimulate the local and deep areas of the brain. However, the detailed cellular mechanisms of neural activation are still unclear because studies on micro-stimulation at the cellular level are lacking. NEW METHOD To modulate neural activity at the cellular level, we developed a piezoelectric micromachined ultrasound transducer (PMUT), having circular diaphragms for application on acute brain slice preparations. To monitor neural activities, additionally, we fabricated recording microelectrodes onto the same PMUT device for closed-loop application. RESULTS To examine the PMUT-driven cellular responses of a brain slice, intracellular calcium signals in individual cells were measured using two calcium indicators. We successfully observed the intracellular responses triggered by the ultrasound of our novel PMUT. In addition, we performed recordings of local field potentials in a brain slice, demonstrating its usefulness as a simultaneous recording interface. COMPARISON WITH EXISTING METHOD(S) Conventional ultrasound stimulators are open-loop systems that risk inducing excessive neural activity because of the absence of neural activity monitoring. In contrast, our PMUT is packaged in a single device with both stimulation and sensor interface for neuromodulation. Further, there are no published reports on in vitro microdevices that can be used for ultrasound stimulation in rodent cortical slices that are several hundred micrometers thick, which maintain the cortical laminar structure and intrinsic neural networks. CONCLUSIONS Our findings suggest that this novel PMUT device has the potential for being a powerful tool for in vitro brain slice applications and effective closed loop ultrasound stimulation.
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Affiliation(s)
- Ryo Furukawa
- Bioengineering and Bioinformatics, Graduate School of Information Science and Technology, Hokkaido University, Kita 14, Nishi 9, Kita-ku, Sapporo 060-0814, Japan.
| | - Takahiro Yoshikawa
- Bioengineering and Bioinformatics, Graduate School of Information Science and Technology, Hokkaido University, Kita 14, Nishi 9, Kita-ku, Sapporo 060-0814, Japan.
| | - Shuichi Murakami
- Osaka Research Institute of Industrial Science and Technology, 2-7-1, Ayumino, Izumi, Osaka 594-1157, Japan.
| | - Takashi Tateno
- Bioengineering and Bioinformatics, Faculty of Information Science and Technology, Hokkaido University, Kita 14, Nishi 9, Kita-ku, Sapporo 060-0814, Japan.
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Shimoda Y, Leite M, Graham RT, Marvin JS, Hasseman J, Kolb I, Looger LL, Magloire V, Kullmann DM. Extracellular glutamate and GABA transients at the transition from interictal spiking to seizures. Brain 2024; 147:1011-1024. [PMID: 37787057 PMCID: PMC10907087 DOI: 10.1093/brain/awad336] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 08/29/2023] [Accepted: 09/16/2023] [Indexed: 10/04/2023] Open
Abstract
Focal epilepsy is associated with intermittent brief population discharges (interictal spikes), which resemble sentinel spikes that often occur at the onset of seizures. Why interictal spikes self-terminate whilst seizures persist and propagate is incompletely understood. We used fluorescent glutamate and GABA sensors in an awake rodent model of neocortical seizures to resolve the spatiotemporal evolution of both neurotransmitters in the extracellular space. Interictal spikes were accompanied by brief glutamate transients which were maximal at the initiation site and rapidly propagated centrifugally. GABA transients lasted longer than glutamate transients and were maximal ∼1.5 mm from the focus where they propagated centripetally. Prior to seizure initiation GABA transients were attenuated, whilst glutamate transients increased, consistent with a progressive failure of local inhibitory restraint. As seizures increased in frequency, there was a gradual increase in the spatial extent of spike-associated glutamate transients associated with interictal spikes. Neurotransmitter imaging thus reveals a progressive collapse of an annulus of feed-forward GABA release, allowing seizures to escape from local inhibitory restraint.
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Affiliation(s)
- Yoshiteru Shimoda
- Department of Clinical & Experimental Epilepsy, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Marco Leite
- Department of Clinical & Experimental Epilepsy, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Robert T Graham
- Department of Clinical & Experimental Epilepsy, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Jonathan S Marvin
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Jeremy Hasseman
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Ilya Kolb
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Loren L Looger
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Vincent Magloire
- Department of Clinical & Experimental Epilepsy, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Dimitri M Kullmann
- Department of Clinical & Experimental Epilepsy, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
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Guo F, Li A, Liu Q, Guo D, Chen K, Yao D, Cui Y, Xia Y. Disruption of TLE epileptiform activity retarded the seizure and reduced pathological HFOs. Brain Res Bull 2024; 207:110869. [PMID: 38184151 DOI: 10.1016/j.brainresbull.2024.110869] [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: 10/31/2023] [Revised: 12/17/2023] [Accepted: 01/01/2024] [Indexed: 01/08/2024]
Abstract
In temporal lobe epilepsy (TLE), the epileptogenic zones, such as the temporal lobe structure, could generate pathological high-frequency oscillations (pHFOs, 250-500 Hz) before the ictal period. These pHFOs have also been observed during the process of seizures in both TLE patients and animals, exhibiting a critical role as promising biomarkers for TLE seizures. TLE seizures could be modulated via regulating the neural excitability in epileptogenic zones, for that TLE is primarily associated with the excitation-inhibition imbalance. However, whether these kinds of modulations could also impact the pHFOs characteristics during TLE seizures is still unclear. For this purpose, we pharmaco-genetically inhibited the principal cells (PCs) in the mouse CA3 region and tracked the difference in the behavioral and electrophysiological features during LiCl-pilocarpine-induced TLE seizure between the hM4Di+CNO (experimental) mice and mCherry+CNO (control) mice. Delayed latency, decreased averaged duration, and reduced counts of the generalized seizure were observed in the experimental mice. Besides, the electrophysiological characteristics, such as the firing rate of PCs and the count of pHFO, exhibited significant decline in the CA3 and CA1 regions. During TLE seizure, there existed strong phase-coupling between pHFO and PCs spike timing in the control mice, while it was abolished in the experimental mice. In addition, we also found that the counts of pHFO were significantly associated with the behavioral features, indicating the close relationships within them. Collectively, our findings suggested that alterations in pHFO and the retardation of seizures may be attributed to disruptions in neuronal excitability, and the variations of electrophysiological features were related to seizure severity during TLE seizures. These results provide valuable insights into the role of pHFOs in TLE and shed light on the underlying mechanisms involved.
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Affiliation(s)
- Fengru Guo
- Department of Neurosurgery, Sichuan Provincial People's Hospital, MOE Key Lab for Neuroinformation, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Airui Li
- Department of Neurosurgery, Sichuan Provincial People's Hospital, MOE Key Lab for Neuroinformation, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Qinjun Liu
- Department of Neurosurgery, Sichuan Provincial People's Hospital, MOE Key Lab for Neuroinformation, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Daqing Guo
- Department of Neurosurgery, Sichuan Provincial People's Hospital, MOE Key Lab for Neuroinformation, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Ke Chen
- Department of Neurosurgery, Sichuan Provincial People's Hospital, MOE Key Lab for Neuroinformation, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Dezhong Yao
- Department of Neurosurgery, Sichuan Provincial People's Hospital, MOE Key Lab for Neuroinformation, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Yan Cui
- Department of Neurosurgery, Sichuan Provincial People's Hospital, MOE Key Lab for Neuroinformation, University of Electronic Science and Technology of China, Chengdu 611731, China.
| | - Yang Xia
- Department of Neurosurgery, Sichuan Provincial People's Hospital, MOE Key Lab for Neuroinformation, University of Electronic Science and Technology of China, Chengdu 611731, China.
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Nguyen QA, Klein PM, Xie C, Benthall KN, Iafrati J, Homidan J, Bendor JT, Dudok B, Farrell JS, Gschwind T, Porter CL, Keravala A, Dodson GS, Soltesz I. Acetylcholine receptor based chemogenetics engineered for neuronal inhibition and seizure control assessed in mice. Nat Commun 2024; 15:601. [PMID: 38238329 PMCID: PMC10796428 DOI: 10.1038/s41467-024-44853-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 01/09/2024] [Indexed: 01/22/2024] Open
Abstract
Epilepsy is a prevalent disorder involving neuronal network hyperexcitability, yet existing therapeutic strategies often fail to provide optimal patient outcomes. Chemogenetic approaches, where exogenous receptors are expressed in defined brain areas and specifically activated by selective agonists, are appealing methods to constrain overactive neuronal activity. We developed BARNI (Bradanicline- and Acetylcholine-activated Receptor for Neuronal Inhibition), an engineered channel comprised of the α7 nicotinic acetylcholine receptor ligand-binding domain coupled to an α1 glycine receptor anion pore domain. Here we demonstrate that BARNI activation by the clinical stage α7 nicotinic acetylcholine receptor-selective agonist bradanicline effectively suppressed targeted neuronal activity, and controlled both acute and chronic seizures in male mice. Our results provide evidence for the use of an inhibitory acetylcholine-based engineered channel activatable by both exogenous and endogenous agonists as a potential therapeutic approach to treating epilepsy.
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Affiliation(s)
- Quynh-Anh Nguyen
- Department of Neurosurgery, Stanford University, Stanford, CA, 94305, USA.
| | - Peter M Klein
- Department of Neurosurgery, Stanford University, Stanford, CA, 94305, USA.
| | - Cheng Xie
- CODA Biotherapeutics, 240 East Grand Ave., South San Francisco, CA, 94080, USA
| | - Katelyn N Benthall
- CODA Biotherapeutics, 240 East Grand Ave., South San Francisco, CA, 94080, USA
| | - Jillian Iafrati
- CODA Biotherapeutics, 240 East Grand Ave., South San Francisco, CA, 94080, USA
| | - Jesslyn Homidan
- Department of Neurosurgery, Stanford University, Stanford, CA, 94305, USA
| | - Jacob T Bendor
- CODA Biotherapeutics, 240 East Grand Ave., South San Francisco, CA, 94080, USA
| | - Barna Dudok
- Department of Neurosurgery, Stanford University, Stanford, CA, 94305, USA
- Department of Neurology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Jordan S Farrell
- Department of Neurosurgery, Stanford University, Stanford, CA, 94305, USA
| | - Tilo Gschwind
- Department of Neurosurgery, Stanford University, Stanford, CA, 94305, USA
| | - Charlotte L Porter
- Department of Neurosurgery, Stanford University, Stanford, CA, 94305, USA
| | - Annahita Keravala
- CODA Biotherapeutics, 240 East Grand Ave., South San Francisco, CA, 94080, USA
| | - G Steven Dodson
- CODA Biotherapeutics, 240 East Grand Ave., South San Francisco, CA, 94080, USA
| | - Ivan Soltesz
- Department of Neurosurgery, Stanford University, Stanford, CA, 94305, USA
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Bernard C, Frauscher B, Gelinas J, Timofeev I. Sleep, oscillations, and epilepsy. Epilepsia 2023; 64 Suppl 3:S3-S12. [PMID: 37226640 PMCID: PMC10674035 DOI: 10.1111/epi.17664] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 04/27/2023] [Accepted: 05/23/2023] [Indexed: 05/26/2023]
Abstract
Sleep and wake are defined through physiological and behavioral criteria and can be typically separated into non-rapid eye movement (NREM) sleep stages N1, N2, and N3, rapid eye movement (REM) sleep, and wake. Sleep and wake states are not homogenous in time. Their properties vary during the night and day cycle. Given that brain activity changes as a function of NREM, REM, and wake during the night and day cycle, are seizures more likely to occur during NREM, REM, or wake at a specific time? More generally, what is the relationship between sleep-wake cycles and epilepsy? We will review specific examples from clinical data and results from experimental models, focusing on the diversity and heterogeneity of these relationships. We will use a top-down approach, starting with the general architecture of sleep, followed by oscillatory activities, and ending with ionic correlates selected for illustrative purposes, with respect to seizures and interictal spikes. The picture that emerges is that of complexity; sleep disruption and pathological epileptic activities emerge from reorganized circuits. That different circuit alterations can occur across patients and models may explain why sleep alterations and the timing of seizures during the sleep-wake cycle are patient-specific.
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Affiliation(s)
| | - Birgit Frauscher
- Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
| | - Jennifer Gelinas
- Institute for Genomic Medicine, Columbia University Medical Center, New York, NY, USA
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Igor Timofeev
- Faculté de Médecine, Département de Psychiatrie et de Neurosciences, Centre de Recherche CERVO, Université Laval, Québec, QC G1J2G3, Canada
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Leontiadis LJ, Trompoukis G, Tsotsokou G, Miliou A, Felemegkas P, Papatheodoropoulos C. Rescue of sharp wave-ripples and prevention of network hyperexcitability in the ventral but not the dorsal hippocampus of a rat model of fragile X syndrome. Front Cell Neurosci 2023; 17:1296235. [PMID: 38107412 PMCID: PMC10722241 DOI: 10.3389/fncel.2023.1296235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 11/06/2023] [Indexed: 12/19/2023] Open
Abstract
Fragile X syndrome (FXS) is a genetic neurodevelopmental disorder characterized by intellectual disability and is related to autism. FXS is caused by mutations of the fragile X messenger ribonucleoprotein 1 gene (Fmr1) and is associated with alterations in neuronal network excitability in several brain areas including hippocampus. The loss of fragile X protein affects brain oscillations, however, the effects of FXS on hippocampal sharp wave-ripples (SWRs), an endogenous hippocampal pattern contributing to memory consolidation have not been sufficiently clarified. In addition, it is still not known whether dorsal and ventral hippocampus are similarly affected by FXS. We used a Fmr1 knock-out (KO) rat model of FXS and electrophysiological recordings from the CA1 area of adult rat hippocampal slices to assess spontaneous and evoked neural activity. We find that SWRs and associated multiunit activity are affected in the dorsal but not the ventral KO hippocampus, while complex spike bursts remain normal in both segments of the KO hippocampus. Local network excitability increases in the dorsal KO hippocampus. Furthermore, specifically in the ventral hippocampus of KO rats we found an increased effectiveness of inhibition in suppressing excitation and an upregulation of α1GABAA receptor subtype. These changes in the ventral KO hippocampus are accompanied by a striking reduction in its susceptibility to induced epileptiform activity. We propose that the neuronal network specifically in the ventral segment of the hippocampus is reorganized in adult Fmr1-KO rats by means of balanced changes between excitability and inhibition to ensure normal generation of SWRs and preventing at the same time derailment of the neural activity toward hyperexcitability.
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10
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Blondiaux A, Jia S, Annamneedi A, Çalışkan G, Nebel J, Montenegro-Venegas C, Wykes RC, Fejtova A, Walker MC, Stork O, Gundelfinger ED, Dityatev A, Seidenbecher CI. Linking epileptic phenotypes and neural extracellular matrix remodeling signatures in mouse models of epilepsy. Neurobiol Dis 2023; 188:106324. [PMID: 37838005 DOI: 10.1016/j.nbd.2023.106324] [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: 05/26/2023] [Revised: 10/11/2023] [Accepted: 10/11/2023] [Indexed: 10/16/2023] Open
Abstract
Epilepsies are multifaceted neurological disorders characterized by abnormal brain activity, e.g. caused by imbalanced synaptic excitation and inhibition. The neural extracellular matrix (ECM) is dynamically modulated by physiological and pathophysiological activity and critically involved in controlling the brain's excitability. We used different epilepsy models, i.e. mice lacking the presynaptic scaffolding protein Bassoon at excitatory, inhibitory or all synapse types as genetic models for rapidly generalizing early-onset epilepsy, and intra-hippocampal kainate injection, a model for acquired temporal lobe epilepsy, to study the relationship between epileptic seizures and ECM composition. Electroencephalogram recordings revealed Bassoon deletion at excitatory or inhibitory synapses having diverse effects on epilepsy-related phenotypes. While constitutive Bsn mutants and to a lesser extent GABAergic neuron-specific knockouts (BsnDlx5/6cKO) displayed severe epilepsy with more and stronger seizures than kainate-injected animals, mutants lacking Bassoon solely in excitatory forebrain neurons (BsnEmx1cKO) showed only mild impairments. By semiquantitative immunoblotting and immunohistochemistry we show model-specific patterns of neural ECM remodeling, and we also demonstrate significant upregulation of the ECM receptor CD44 in null and BsnDlx5/6cKO mutants. ECM-associated WFA-binding chondroitin sulfates were strongly augmented in seizure models. Strikingly, Brevican, Neurocan, Aggrecan and link proteins Hapln1 and Hapln4 levels reliably predicted seizure properties across models, suggesting a link between ECM state and epileptic phenotype.
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Affiliation(s)
| | - Shaobo Jia
- German Center for Neurodegenerative Diseases, Site Magdeburg (DZNE), Magdeburg, Germany
| | - Anil Annamneedi
- Leibniz Institute for Neurobiology (LIN), Magdeburg, Germany; Institute of Biology, Otto-Von-Guericke University, Magdeburg, Germany; Center for Behavioral Brain Sciences (CBBS), Magdeburg 39120, Germany
| | - Gürsel Çalışkan
- Institute of Biology, Otto-Von-Guericke University, Magdeburg, Germany; Center for Behavioral Brain Sciences (CBBS), Magdeburg 39120, Germany
| | - Jana Nebel
- Leibniz Institute for Neurobiology (LIN), Magdeburg, Germany
| | - Carolina Montenegro-Venegas
- Leibniz Institute for Neurobiology (LIN), Magdeburg, Germany; Center for Behavioral Brain Sciences (CBBS), Magdeburg 39120, Germany; Institute for Pharmacology and Toxicology, Otto von Guericke University, Magdeburg, Germany
| | - Robert C Wykes
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK; Nanomedicine Lab & Geoffrey Jefferson Brain Research Center, University of Manchester, Manchester M13 9PT, UK
| | - Anna Fejtova
- Molecular Psychiatry, Department of Psychiatry and Psychotherapy, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Matthew C Walker
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK
| | - Oliver Stork
- Institute of Biology, Otto-Von-Guericke University, Magdeburg, Germany; Center for Behavioral Brain Sciences (CBBS), Magdeburg 39120, Germany
| | - Eckart D Gundelfinger
- Leibniz Institute for Neurobiology (LIN), Magdeburg, Germany; Center for Behavioral Brain Sciences (CBBS), Magdeburg 39120, Germany; Institute for Pharmacology and Toxicology, Otto von Guericke University, Magdeburg, Germany.
| | - Alexander Dityatev
- German Center for Neurodegenerative Diseases, Site Magdeburg (DZNE), Magdeburg, Germany; Center for Behavioral Brain Sciences (CBBS), Magdeburg 39120, Germany; Medical Faculty, Otto-von-Guericke University, Magdeburg, Germany.
| | - Constanze I Seidenbecher
- Leibniz Institute for Neurobiology (LIN), Magdeburg, Germany; Center for Behavioral Brain Sciences (CBBS), Magdeburg 39120, Germany.
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11
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Vivien J, El Azraoui A, Lheraux C, Lanore F, Aouizerate B, Herry C, Humeau Y, Bienvenu TCM. Axo-axonic cells in neuropsychiatric disorders: a systematic review. Front Cell Neurosci 2023; 17:1212202. [PMID: 37435048 PMCID: PMC10330806 DOI: 10.3389/fncel.2023.1212202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 06/09/2023] [Indexed: 07/13/2023] Open
Abstract
Imbalance between excitation and inhibition in the cerebral cortex is one of the main theories in neuropsychiatric disorder pathophysiology. Cortical inhibition is finely regulated by a variety of highly specialized GABAergic interneuron types, which are thought to organize neural network activities. Among interneurons, axo-axonic cells are unique in making synapses with the axon initial segment of pyramidal neurons. Alterations of axo-axonic cells have been proposed to be implicated in disorders including epilepsy, schizophrenia and autism spectrum disorder. However, evidence for the alteration of axo-axonic cells in disease has only been examined in narrative reviews. By performing a systematic review of studies investigating axo-axonic cells and axo-axonic communication in epilepsy, schizophrenia and autism spectrum disorder, we outline convergent findings and discrepancies in the literature. Overall, the implication of axo-axonic cells in neuropsychiatric disorders might have been overstated. Additional work is needed to assess initial, mostly indirect findings, and to unravel how defects in axo-axonic cells translates to cortical dysregulation and, in turn, to pathological states.
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Affiliation(s)
- Juliette Vivien
- Université de Bordeaux, Inserm Neurocentre Magendie U1215, Bordeaux, France
| | - Anass El Azraoui
- Université de Bordeaux, Inserm Neurocentre Magendie U1215, Bordeaux, France
- Univ Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, Bordeaux, France
| | - Cloé Lheraux
- Université de Bordeaux, Inserm Neurocentre Magendie U1215, Bordeaux, France
| | - Frederic Lanore
- Centre Hospitalier Charles Perrens, Inserm Neurocentre Magendie U1215, Bordeaux, France
| | - Bruno Aouizerate
- Université de Bordeaux, Inserm Neurocentre Magendie U1215, Bordeaux, France
- Centre Hospitalier Charles Perrens, Inserm Neurocentre Magendie U1215, Bordeaux, France
- INRAE, Bordeaux INP, NutriNeuro, UMR 1286, Bordeaux, France
| | - Cyril Herry
- Université de Bordeaux, Inserm Neurocentre Magendie U1215, Bordeaux, France
| | - Yann Humeau
- Univ Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, Bordeaux, France
| | - Thomas C. M. Bienvenu
- Université de Bordeaux, Inserm Neurocentre Magendie U1215, Bordeaux, France
- Centre Hospitalier Charles Perrens, Inserm Neurocentre Magendie U1215, Bordeaux, France
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12
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Firestone E, Sonoda M, Kuroda N, Sakakura K, Jeong JW, Lee MH, Wada K, Takayama Y, Iijima K, Iwasaki M, Miyazaki T, Asano E. Sevoflurane-induced high-frequency oscillations, effective connectivity and intraoperative classification of epileptic brain areas. Clin Neurophysiol 2023; 150:17-30. [PMID: 36989866 PMCID: PMC10192072 DOI: 10.1016/j.clinph.2023.03.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 02/27/2023] [Accepted: 03/02/2023] [Indexed: 03/18/2023]
Abstract
OBJECTIVE To determine how sevoflurane anesthesia modulates intraoperative epilepsy biomarkers on electrocorticography, including high-frequency oscillation (HFO) effective connectivity (EC), and to investigate their relation to epileptogenicity and anatomical white matter. METHODS We studied eight pediatric drug-resistant focal epilepsy patients who achieved seizure control after invasive monitoring and resective surgery. We visualized spatial distributions of the electrocorticography biomarkers at an oxygen baseline, three time-points while sevoflurane was increasing, and at a plateau of 2 minimum alveolar concentration (MAC) sevoflurane. HFO EC was combined with diffusion-weighted imaging, in dynamic tractography. RESULTS Intraoperative HFO EC diffusely increased as a function of sevoflurane concentration, although most in epileptogenic sites (defined as those included in the resection); their ability to classify epileptogenicity was optimized at sevoflurane 2 MAC. HFO EC could be visualized on major white matter tracts, as a function of sevoflurane level. CONCLUSIONS The results strengthened the hypothesis that sevoflurane-activated HFO biomarkers may help intraoperatively localize the epileptogenic zone. SIGNIFICANCE Our results help characterize how HFOs at non-epileptogenic and epileptogenic networks respond to sevoflurane. It may be warranted to establish a normative HFO atlas incorporating the modifying effects of sevoflurane and major white matter pathways, as critical reference in epilepsy presurgical evaluation.
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Affiliation(s)
- Ethan Firestone
- Department of Pediatrics, Children's Hospital of Michigan, Detroit Medical Center,Wayne State University, Detroit, MI 48201, USA; Department of Physiology, Wayne State University, Detroit, MI 48201, USA
| | - Masaki Sonoda
- Department of Pediatrics, Children's Hospital of Michigan, Detroit Medical Center,Wayne State University, Detroit, MI 48201, USA; Department of Neurosurgery, Yokohama City University Graduate School of Medicine, Yokohama 2360004, Japan
| | - Naoto Kuroda
- Department of Pediatrics, Children's Hospital of Michigan, Detroit Medical Center,Wayne State University, Detroit, MI 48201, USA; Department of Epileptology, Tohoku University Graduate School of Medicine, Sendai 9808575, Japan
| | - Kazuki Sakakura
- Department of Pediatrics, Children's Hospital of Michigan, Detroit Medical Center,Wayne State University, Detroit, MI 48201, USA; Department of Neurosurgery, University of Tsukuba, Tsukuba 3058575, Japan
| | - Jeong-Won Jeong
- Department of Pediatrics, Children's Hospital of Michigan, Detroit Medical Center,Wayne State University, Detroit, MI 48201, USA; Department of Neurology, Children's Hospital of Michigan, Detroit Medical Center, Wayne State University, Detroit, MI 48201, USA
| | - Min-Hee Lee
- Department of Pediatrics, Children's Hospital of Michigan, Detroit Medical Center,Wayne State University, Detroit, MI 48201, USA
| | - Keiko Wada
- Department of Anesthesiology, National Center Hospital, National Center of Neurology and Psychiatry, Kodaira, Tokyo 1878551, Japan; Department of Anesthesiology and Critical Care, Yokohama City University Graduate School of Medicine, Yokohama 2360004, Japan
| | - Yutaro Takayama
- Department of Neurosurgery, Yokohama City University Graduate School of Medicine, Yokohama 2360004, Japan; Department of Neurosurgery, National Center Hospital, National Center of Neurology and Psychiatry, Kodaira, Tokyo 1878551, Japan
| | - Keiya Iijima
- Department of Neurosurgery, National Center Hospital, National Center of Neurology and Psychiatry, Kodaira, Tokyo 1878551, Japan
| | - Masaki Iwasaki
- Department of Neurosurgery, National Center Hospital, National Center of Neurology and Psychiatry, Kodaira, Tokyo 1878551, Japan
| | - Tomoyuki Miyazaki
- Department of Anesthesiology, National Center Hospital, National Center of Neurology and Psychiatry, Kodaira, Tokyo 1878551, Japan; Department of Physiology, Yokohama City University Graduate School of Medicine, Yokohama 2360004, Japan
| | - Eishi Asano
- Department of Pediatrics, Children's Hospital of Michigan, Detroit Medical Center,Wayne State University, Detroit, MI 48201, USA; Department of Neurology, Children's Hospital of Michigan, Detroit Medical Center, Wayne State University, Detroit, MI 48201, USA.
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13
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Magloire V, Savtchenko LP, Jensen TP, Sylantyev S, Kopach O, Cole N, Tyurikova O, Kullmann DM, Walker MC, Marvin JS, Looger LL, Hasseman JP, Kolb I, Pavlov I, Rusakov DA. Volume-transmitted GABA waves pace epileptiform rhythms in the hippocampal network. Curr Biol 2023; 33:1249-1264.e7. [PMID: 36921605 PMCID: PMC10615848 DOI: 10.1016/j.cub.2023.02.051] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 01/05/2023] [Accepted: 02/15/2023] [Indexed: 03/17/2023]
Abstract
Mechanisms that entrain and pace rhythmic epileptiform discharges remain debated. Traditionally, the quest to understand them has focused on interneuronal networks driven by synaptic GABAergic connections. However, synchronized interneuronal discharges could also trigger the transient elevations of extracellular GABA across the tissue volume, thus raising tonic conductance (Gtonic) of synaptic and extrasynaptic GABA receptors in multiple cells. Here, we monitor extracellular GABA in hippocampal slices using patch-clamp GABA "sniffer" and a novel optical GABA sensor, showing that periodic epileptiform discharges are preceded by transient, region-wide waves of extracellular GABA. Neural network simulations that incorporate volume-transmitted GABA signals point to a cycle of GABA-driven network inhibition and disinhibition underpinning this relationship. We test and validate this hypothesis using simultaneous patch-clamp recordings from multiple neurons and selective optogenetic stimulation of fast-spiking interneurons. Critically, reducing GABA uptake in order to decelerate extracellular GABA fluctuations-without affecting synaptic GABAergic transmission or resting GABA levels-slows down rhythmic activity. Our findings thus unveil a key role of extrasynaptic, volume-transmitted GABA in pacing regenerative rhythmic activity in brain networks.
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Affiliation(s)
- Vincent Magloire
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK.
| | - Leonid P Savtchenko
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK.
| | - Thomas P Jensen
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
| | - Sergyi Sylantyev
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK; Rowett Institute, University of Aberdeen, Ashgrove Road West, Aberdeen AB25 2ZD, UK
| | - Olga Kopach
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
| | - Nicholas Cole
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
| | - Olga Tyurikova
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
| | - Dimitri M Kullmann
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
| | - Matthew C Walker
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
| | - Jonathan S Marvin
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Loren L Looger
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA; Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093, USA; GENIE Project Team, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Jeremy P Hasseman
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA; GENIE Project Team, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Ilya Kolb
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA; GENIE Project Team, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Ivan Pavlov
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
| | - Dmitri A Rusakov
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK.
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14
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Lippmann K, Klaft ZJ, Salar S, Hollnagel JO, Valero M, Maslarova A. Status epilepticus induces chronic silencing of burster and dominance of regular firing neurons during sharp wave-ripples in the mouse subiculum. Neurobiol Dis 2022; 175:105929. [DOI: 10.1016/j.nbd.2022.105929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 11/08/2022] [Accepted: 11/17/2022] [Indexed: 11/23/2022] Open
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15
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Kalogeropoulos K, Kleidonas D, Psarropoulou C. Timing differences between HFOs and interictal epileptiform discharges generated in vitro by different mechanisms in rat hippocampal slices: A novel approach. Epilepsia Open 2022; 7:608-615. [PMID: 35908206 PMCID: PMC9712485 DOI: 10.1002/epi4.12633] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 07/28/2022] [Indexed: 12/30/2022] Open
Abstract
OBJECTIVE To investigate the effect of generating mechanism on the relationship between interictal-like epileptiform discharges (IEDs) and the underlying High Frequency Oscillations (HFOs; Ripples, R, and Fast Ripples, FR). METHODS Synchronous spontaneous IEDs were recorded from the CA1 area of hippocampal slices from adult rats, perfused by Mg2+ -free ACSF (n = 41slices/14 animals) or 4-aminopyridine (50 μM, n = 37slices/16 animals); IED filtering revealed Rs and FRs and several metrics were calculated and compared (amplitude, duration, relative onset, time lag, % overlap, peak frequency, peak power, FR/R). RESULTS Longer IEDs and higher 1st Population Spike (PS) amplitude in Mg2+ -free ACSF (vs 4-AP; P < .001, P < .001) correlated with longer duration and higher amplitude Rs (P < .0001, P = .001) and longer duration FRs (P < .001). In both media, Rs and FRs appeared before IED onset with Rs preceding FRs; R- and FR-IED lag (P = .008, P = .01) as well as R-FR lag (P = .04) were significantly longer in Mg2+ -free ACSF vs in 4-AP. R peak frequency and power were higher in Mg2+ -free ACSF, while no such differences were observed in FRs. Inter-model differences were mostly reflected in Rs, not FRs, suggesting that mechanisms unique to R generation are more active in Mg2+ -free ACSF vs in 4-AP. FRs appeared to contribute equally to IEDs irrespective of generating mechanism. SIGNIFICANCE Several of the metrics used, particularly those regarding the timing between HFOs and IEDs, appear to correlate with the synchronizing mechanism and we propose that they may be useful when investigating antiepileptic substance effects on neuronal network activity.
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Affiliation(s)
- Konstantinos Kalogeropoulos
- Laboratory of Animal and Human Physiology, Department of Biological Applications and Technology, Faculty of Health SciencesUniversity of IoanninaIoanninaGreece
| | - Dimitrios Kleidonas
- Laboratory of Animal and Human Physiology, Department of Biological Applications and Technology, Faculty of Health SciencesUniversity of IoanninaIoanninaGreece,Department of Neuroanatomy, Faculty of MedicineInstitute of Anatomy and Cell Biology, University of FreiburgFreiburgGermany
| | - Caterina Psarropoulou
- Laboratory of Animal and Human Physiology, Department of Biological Applications and Technology, Faculty of Health SciencesUniversity of IoanninaIoanninaGreece,Department of Biological Applications & TechnologiesUniversity of IoanninaIoanninaGreece
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16
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Vrontou S, Bédécarrats A, Wei X, Ayodeji M, Brassai A, Molnár L, Mody I. Altered brain rhythms and behaviour in the accelerated ovarian failure mouse model of human menopause. Brain Commun 2022; 4:fcac166. [PMID: 35794872 PMCID: PMC9253886 DOI: 10.1093/braincomms/fcac166] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 03/30/2022] [Accepted: 06/20/2022] [Indexed: 11/14/2022] Open
Abstract
To date, potential mechanisms of menopause-related memory and cognitive deficits have not been elucidated. Therefore, we studied brain oscillations, their phase–amplitude coupling, sleep and vigilance state patterns, running wheel use and other behavioural measures in a translationally valid mouse model of menopause, the 4-vinylcyclohexene-diepoxide-induced accelerated ovarian failure. After accelerated ovarian failure, female mice show significant alterations in brain rhythms, including changes in the frequencies of θ (5–12 Hz) and γ (30–120 Hz) oscillations, a reversed phase–amplitude coupling, altered coupling of hippocampal sharp-wave ripples to medial prefrontal cortical sleep spindles and reduced δ oscillation (0.5–4 Hz) synchrony between the two regions during non-rapid eye movement sleep. In addition, we report on significant circadian variations in the frequencies of θ and γ oscillations, and massive synchronous δ oscillations during wheel running. Our results reveal novel and specific network alterations and feasible signs for diminished brain connectivity in the accelerated ovarian failure mouse model of menopause. Taken together, our results may have identified changes possibly responsible for some of the memory and cognitive deficits previously described in this model. Corresponding future studies in menopausal women could shed light on fundamental mechanisms underlying the neurological and psychiatric comorbidities present during this important transitional phase in women’s lives.
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Affiliation(s)
- Sophia Vrontou
- Department of Neurology, The David Geffen School of Medicine at UCLA , Los Angeles, CA 90095 , USA
| | - Alexis Bédécarrats
- Department of Neurology, The David Geffen School of Medicine at UCLA , Los Angeles, CA 90095 , USA
| | - Xiaofei Wei
- Department of Neurology, The David Geffen School of Medicine at UCLA , Los Angeles, CA 90095 , USA
| | | | - Attila Brassai
- Department of Pharmacology, George Emil Palade University of Medicine, Pharmacy, Sciences and Technology , Târgu Mureş 540139 , Romania
| | - László Molnár
- Department of Electrical Engineering, Sapientia Hungarian University of Transylvania , Târgu Mureş 540485 , Romania
| | - Istvan Mody
- Department of Neurology, The David Geffen School of Medicine at UCLA , Los Angeles, CA 90095 , USA
- Department of Physiology, The David Geffen School of Medicine at UCLA , Los Angeles, CA 90095 , USA
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17
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Hofer KT, Kandrács Á, Tóth K, Hajnal B, Bokodi V, Tóth EZ, Erőss L, Entz L, Bagó AG, Fabó D, Ulbert I, Wittner L. Bursting of excitatory cells is linked to interictal epileptic discharge generation in humans. Sci Rep 2022; 12:6280. [PMID: 35428851 PMCID: PMC9012754 DOI: 10.1038/s41598-022-10319-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 03/25/2022] [Indexed: 11/23/2022] Open
Abstract
Knowledge about the activity of single neurons is essential in understanding the mechanisms of synchrony generation, and particularly interesting if related to pathological conditions. The generation of interictal spikes—the hypersynchronous events between seizures—is linked to hyperexcitability and to bursting behaviour of neurons in animal models. To explore its cellular mechanisms in humans we investigated the activity of clustered single neurons in a human in vitro model generating both physiological and epileptiform synchronous events. We show that non-epileptic synchronous events resulted from the finely balanced firing of excitatory and inhibitory cells, which was shifted towards an enhanced excitability in epileptic tissue. In contrast, interictal-like spikes were characterised by an asymmetric overall neuronal discharge initiated by excitatory neurons with the presumptive leading role of bursting pyramidal cells, and possibly terminated by inhibitory interneurons. We found that the overall burstiness of human neocortical neurons is not necessarily related to epilepsy, but the bursting behaviour of excitatory cells comprising both intrinsic and synaptically driven bursting is clearly linked to the generation of epileptiform synchrony.
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Affiliation(s)
- Katharina T Hofer
- Institute of Cognitive Neuroscience and Psychology, Research Center for Natural Sciences, Eötvös Loránd Research Network, Magyar tudósok körútja 2., 1117, Budapest, Hungary.,Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, 1083, Budapest, Hungary.,Department of Neurobiology, School of Medicine and Institute for Medical Research Israel-Canada, The Hebrew University, 91120, Jerusalem, Israel
| | - Ágnes Kandrács
- Institute of Cognitive Neuroscience and Psychology, Research Center for Natural Sciences, Eötvös Loránd Research Network, Magyar tudósok körútja 2., 1117, Budapest, Hungary.,Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, 1083, Budapest, Hungary
| | - Kinga Tóth
- Institute of Cognitive Neuroscience and Psychology, Research Center for Natural Sciences, Eötvös Loránd Research Network, Magyar tudósok körútja 2., 1117, Budapest, Hungary
| | - Boglárka Hajnal
- National Institute of Mental Health, Neurology and Neurosurgery, 1143, Budapest, Hungary.,Semmelweis University Doctoral School, 1026, Budapest, Hungary
| | - Virág Bokodi
- National Institute of Mental Health, Neurology and Neurosurgery, 1143, Budapest, Hungary
| | - Estilla Zsófia Tóth
- Institute of Cognitive Neuroscience and Psychology, Research Center for Natural Sciences, Eötvös Loránd Research Network, Magyar tudósok körútja 2., 1117, Budapest, Hungary.,Semmelweis University Doctoral School, 1026, Budapest, Hungary
| | - Loránd Erőss
- National Institute of Mental Health, Neurology and Neurosurgery, 1143, Budapest, Hungary
| | - László Entz
- National Institute of Mental Health, Neurology and Neurosurgery, 1143, Budapest, Hungary
| | - Attila G Bagó
- National Institute of Mental Health, Neurology and Neurosurgery, 1143, Budapest, Hungary
| | - Dániel Fabó
- National Institute of Mental Health, Neurology and Neurosurgery, 1143, Budapest, Hungary
| | - István Ulbert
- Institute of Cognitive Neuroscience and Psychology, Research Center for Natural Sciences, Eötvös Loránd Research Network, Magyar tudósok körútja 2., 1117, Budapest, Hungary.,Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, 1083, Budapest, Hungary.,National Institute of Mental Health, Neurology and Neurosurgery, 1143, Budapest, Hungary
| | - Lucia Wittner
- Institute of Cognitive Neuroscience and Psychology, Research Center for Natural Sciences, Eötvös Loránd Research Network, Magyar tudósok körútja 2., 1117, Budapest, Hungary. .,Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, 1083, Budapest, Hungary. .,National Institute of Mental Health, Neurology and Neurosurgery, 1143, Budapest, Hungary.
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18
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B. Szabo A, Cretin B, Gérard F, Curot J, J. Barbeau E, Pariente J, Dahan L, Valton L. Sleep: The Tip of the Iceberg in the Bidirectional Link Between Alzheimer's Disease and Epilepsy. Front Neurol 2022; 13:836292. [PMID: 35481265 PMCID: PMC9035794 DOI: 10.3389/fneur.2022.836292] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 02/14/2022] [Indexed: 11/13/2022] Open
Abstract
The observation that a pathophysiological link might exist between Alzheimer's disease (AD) and epilepsy dates back to the identification of the first cases of the pathology itself and is now strongly supported by an ever-increasing mountain of literature. An overwhelming majority of data suggests not only a higher prevalence of epilepsy in Alzheimer's disease compared to healthy aging, but also that AD patients with a comorbid epileptic syndrome, even subclinical, have a steeper cognitive decline. Moreover, clinical and preclinical investigations have revealed a marked sleep-related increase in the frequency of epileptic activities. This characteristic might provide clues to the pathophysiological pathways underlying this comorbidity. Furthermore, the preferential sleep-related occurrence of epileptic events opens up the possibility that they might hasten cognitive decline by interfering with the delicately orchestrated synchrony of oscillatory activities implicated in sleep-related memory consolidation. Therefore, we scrutinized the literature for mechanisms that might promote sleep-related epileptic activity in AD and, possibly dementia onset in epilepsy, and we also aimed to determine to what degree and through which processes such events might alter the progression of AD. Finally, we discuss the implications for patient care and try to identify a common basis for methodological considerations for future research and clinical practice.
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Affiliation(s)
- Anna B. Szabo
- Centre de Recherches sur la Cognition Animale, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, Toulouse, France
- Centre de Recherche Cerveau & Cognition (CerCo), UMR 5549, CNRS-UPS, Toulouse, France
- *Correspondence: Anna B. Szabo
| | - Benjamin Cretin
- Clinical Neuropsychology Unit, Neurology Department, CM2R (Memory Resource and Research Centre), University Hospital of Strasbourg, Strasbourg, France
- CNRS, ICube Laboratory, UMR 7357 and FMTS (Fédération de Médecine Translationnelle de Strasbourg), Team IMIS, University of Strasbourg, Strasbourg, France
- CMRR d'Alsace, Service de Neurologie des Hôpitaux Universitaires de Strasbourg, Pôle Tête et Cou, Strasbourg, France
| | - Fleur Gérard
- Centre de Recherche Cerveau & Cognition (CerCo), UMR 5549, CNRS-UPS, Toulouse, France
- Neurology Department, Hôpital Purpan Centre Hospitalier Universitaire de Toulouse, Toulouse, France
| | - Jonathan Curot
- Centre de Recherche Cerveau & Cognition (CerCo), UMR 5549, CNRS-UPS, Toulouse, France
- Neurology Department, Hôpital Purpan Centre Hospitalier Universitaire de Toulouse, Toulouse, France
| | - Emmanuel J. Barbeau
- Centre de Recherche Cerveau & Cognition (CerCo), UMR 5549, CNRS-UPS, Toulouse, France
| | - Jérémie Pariente
- Neurology Department, Hôpital Purpan Centre Hospitalier Universitaire de Toulouse, Toulouse, France
- Toulouse NeuroImaging Center (ToNIC), INSERM-University of Toulouse Paul Sabatier, Toulouse, France
| | - Lionel Dahan
- Centre de Recherches sur la Cognition Animale, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Luc Valton
- Centre de Recherche Cerveau & Cognition (CerCo), UMR 5549, CNRS-UPS, Toulouse, France
- Neurology Department, Hôpital Purpan Centre Hospitalier Universitaire de Toulouse, Toulouse, France
- Luc Valton
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19
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Perisomatic Inhibition and Its Relation to Epilepsy and to Synchrony Generation in the Human Neocortex. Int J Mol Sci 2021; 23:ijms23010202. [PMID: 35008628 PMCID: PMC8745731 DOI: 10.3390/ijms23010202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 12/21/2021] [Accepted: 12/22/2021] [Indexed: 11/21/2022] Open
Abstract
Inhibitory neurons innervating the perisomatic region of cortical excitatory principal cells are known to control the emergence of several physiological and pathological synchronous events, including epileptic interictal spikes. In humans, little is known about their role in synchrony generation, although their changes in epilepsy have been thoroughly investigated. This paper demonstraits how parvalbumin (PV)- and type 1 cannabinoid receptor (CB1R)-positive perisomatic interneurons innervate pyramidal cell bodies, and their role in synchronous population events spontaneously emerging in the human epileptic and non-epileptic neocortex, in vitro. Quantitative electron microscopy showed that the overall, PV+ and CB1R+ somatic inhibitory inputs remained unchanged in focal cortical epilepsy. On the contrary, the size of PV-stained synapses increased, and their number decreased in epileptic samples, in synchrony generating regions. Pharmacology demonstrated—in conjunction with the electron microscopy—that although both perisomatic cell types participate, PV+ cells have stronger influence on the generation of population activity in epileptic samples. The somatic inhibitory input of neocortical pyramidal cells remained almost intact in epilepsy, but the larger and consequently more efficient somatic synapses might account for a higher synchrony in this neuron population. This, together with epileptic hyperexcitability, might make a cortical region predisposed to generate or participate in hypersynchronous events.
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20
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Hijacking of hippocampal-cortical oscillatory coupling during sleep in temporal lobe epilepsy. Epilepsy Behav 2021; 121:106608. [PMID: 31740330 DOI: 10.1016/j.yebeh.2019.106608] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 10/11/2019] [Accepted: 10/11/2019] [Indexed: 11/21/2022]
Abstract
Memory impairment is the most common cognitive deficit in patients with temporal lobe epilepsy (TLE). This type of epilepsy is currently regarded as a network disease because of its brain-wide alterations in functional connectivity between temporal and extra-temporal regions. In patients with TLE, network dysfunctions can be observed during ictal states, but are also described interictally during rest or sleep. Here, we examined the available literature supporting the hypothesis that hippocampal-cortical coupling during sleep is hijacked in TLE. First, we look at studies showing that the coordination between hippocampal sharp-wave ripples (100-200 Hz), corticothalamic spindles (9-16 Hz), and cortical delta waves (1-4 Hz) during nonrapid eye movement (NREM) sleep is critical for spatial memory consolidation. Then, we reviewed studies showing that animal models of TLE display precise coordination between hippocampal interictal epileptiform discharges (IEDs) and spindle oscillations in the prefrontal cortex. This aberrant oscillatory coupling seems to surpass the physiological ripple-delta-spindle coordination, which could underlie memory consolidation impairments. We also discuss the role of rapid eye movement (REM) sleep for local synaptic plasticity and memory. Sleep episodes of REM provide windows of opportunity for reactivation of expression of immediate early genes (i.e., zif-268 and Arc). Besides, hippocampal theta oscillations during REM sleep seem to be critical for memory consolidation of novel object place recognition task. However, it is still unclear which extend this particular phase of sleep is affected in TLE. In this context, we show some preliminary results from our group, suggesting that hippocampal theta-gamma phase-amplitude coupling is exacerbated during REM in a model of basolateral amygdala fast kindling. In conclusion, there is an increasing body of evidence suggesting that circuits responsible for memory consolidation during sleep seem to be gradually coopted and degraded in TLE. This article is part of the Special Issue "NEWroscience 2018".
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21
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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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22
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Dubanet O, Ferreira Gomes Da Silva A, Frick A, Hirase H, Beyeler A, Leinekugel X. Probing the polarity of spontaneous perisomatic GABAergic synaptic transmission in the mouse CA3 circuit in vivo. Cell Rep 2021; 36:109381. [PMID: 34260906 DOI: 10.1016/j.celrep.2021.109381] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 11/18/2020] [Accepted: 06/18/2021] [Indexed: 11/27/2022] Open
Abstract
The hypothesis that reversed, excitatory GABA may be involved in various brain pathologies, including epileptogenesis, is appealing but controversial because of the technical difficulty of probing endogenous GABAergic synaptic function in vivo. We overcome this challenge by non-invasive extracellular recording of neuronal firing responses to optogenetically evoked and spontaneously occurring inhibitory perisomatic GABAergic field potentials, generated by individual parvalbumin interneurons on their target pyramidal cells. Our direct probing of GABAergic transmission suggests a rather anecdotal participation of excitatory GABA in two specific models of epileptogenesis in the mouse CA3 circuit in vivo, even though this does not preclude its expression in other brain areas or pathological conditions. Our approach allows the detection of distinct alterations of inhibition during spontaneous activity in vivo, with high sensitivity. It represents a promising tool for the investigation of excitatory GABA in different pathological conditions that may affect the hippocampal circuit.
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Affiliation(s)
- Olivier Dubanet
- University of Bordeaux, INSERM U1215, Neurocentre Magendie, 33077 Bordeaux, France
| | - Arnaldo Ferreira Gomes Da Silva
- University of Bordeaux, INSERM U1215, Neurocentre Magendie, 33077 Bordeaux, France; INMED, INSERM, Aix Marseille Univ, France
| | - Andreas Frick
- University of Bordeaux, INSERM U1215, Neurocentre Magendie, 33077 Bordeaux, France
| | - Hajime Hirase
- Center for Translational Neuromedicine, University of Copenhagen, Copenhagen, Denmark
| | - Anna Beyeler
- University of Bordeaux, INSERM U1215, Neurocentre Magendie, 33077 Bordeaux, France
| | - Xavier Leinekugel
- University of Bordeaux, INSERM U1215, Neurocentre Magendie, 33077 Bordeaux, France; INMED, INSERM, Aix Marseille Univ, France.
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23
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Liu H, Tufa U, Zahra A, Chow J, Sivanenthiran N, Cheng C, Liu Y, Cheung P, Lim S, Jin Y, Mao M, Sun Y, Wu C, Wennberg R, Bardakjian B, Carlen PL, Eubanks JH, Song H, Zhang L. Electrographic Features of Spontaneous Recurrent Seizures in a Mouse Model of Extended Hippocampal Kindling. Cereb Cortex Commun 2021; 2:tgab004. [PMID: 34296153 PMCID: PMC8152854 DOI: 10.1093/texcom/tgab004] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 01/08/2021] [Accepted: 01/13/2021] [Indexed: 01/14/2023] Open
Abstract
Epilepsy is a chronic neurological disorder characterized by spontaneous recurrent seizures (SRS) and comorbidities. Kindling through repetitive brief stimulation of a limbic structure is a commonly used model of temporal lobe epilepsy. Particularly, extended kindling over a period up to a few months can induce SRS, which may simulate slowly evolving epileptogenesis of temporal lobe epilepsy. Currently, electroencephalographic (EEG) features of SRS in rodent models of extended kindling remain to be detailed. We explored this using a mouse model of extended hippocampal kindling. Intracranial EEG recordings were made from the kindled hippocampus and unstimulated hippocampal, neocortical, piriform, entorhinal, or thalamic area in individual mice. Spontaneous EEG discharges with concurrent low-voltage fast onsets were observed from the two corresponding areas in nearly all SRS detected, irrespective of associated motor seizures. Examined in brain slices, epileptiform discharges were induced by alkaline artificial cerebrospinal fluid in the hippocampal CA3, piriform and entorhinal cortical areas of extended kindled mice but not control mice. Together, these in vivo and in vitro observations suggest that the epileptic activity involving a macroscopic network may generate concurrent discharges in forebrain areas and initiate SRS in hippocampally kindled mice.
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Affiliation(s)
- Haiyu Liu
- Departments of Neurosurgery, The First Hospital of Jilin University, Changchun, Jilin 130021 China.,Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8
| | - Uilki Tufa
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8.,Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario M5S 3H5, Canada
| | - Anya Zahra
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8
| | - Jonathan Chow
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8
| | - Nila Sivanenthiran
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8
| | - Chloe Cheng
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8
| | - Yapg Liu
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8
| | - Phinehas Cheung
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8
| | - Stellar Lim
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8
| | - Yaozhong Jin
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8
| | - Min Mao
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8
| | - Yuqing Sun
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8
| | - Chiping Wu
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8
| | - Richard Wennberg
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8.,Department of Medicine, University of Toronto, Toronto, Ontario M2K 1E2, Canada
| | - Berj Bardakjian
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario M5S 3H5, Canada
| | - Peter L Carlen
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8.,Department of Medicine, University of Toronto, Toronto, Ontario M2K 1E2, Canada.,Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - James H Eubanks
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8.,Department of Surgery, University of Toronto, Toronto, Ontario M5G 1X5, Canada
| | - Hongmei Song
- Departments of Neurosurgery, The First Hospital of Jilin University, Changchun, Jilin 130021 China.,Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8
| | - Liang Zhang
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8.,Department of Medicine, University of Toronto, Toronto, Ontario M2K 1E2, Canada
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24
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Serrano-Reyes M, García-Vilchis B, Reyes-Chapero R, Cáceres-Chávez VA, Tapia D, Galarraga E, Bargas J. Spontaneous Activity of Neuronal Ensembles in Mouse Motor Cortex: Changes after GABAergic Blockade. Neuroscience 2020; 446:304-322. [PMID: 32860933 DOI: 10.1016/j.neuroscience.2020.08.025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 08/02/2020] [Accepted: 08/18/2020] [Indexed: 01/12/2023]
Abstract
The mouse motor cortex exhibits spontaneous activity in the form of temporal sequences of neuronal ensembles in vitro without the need of tissue stimulation. These neuronal ensembles are defined as groups of neurons with a strong correlation between its firing patterns, generating what appears to be a predetermined neural conduction mode that needs study. Each ensemble is commonly accompanied by one or more parvalbumin expressing neurons (PV+) or fast spiking interneurons. Many of these interneurons have functional connections between them, helping to form a circuit configuration similar to a small-world network. However, rich club metrics show that most connected neurons are neurons not expressing parvalbumin, mainly pyramidal neurons (PV-) suggesting feed-forward propagation through pyramidal cells. Ensembles with PV+ neurons are connected to these hubs. When ligand-gated fast GABAergic transmission is blocked, temporal sequences of ensembles collapse into a unique synchronous and recurrent ensemble, showing the need of inhibition for coding cortical spontaneous activity. This new ensemble has a duration and electrophysiological characteristics of brief recurrent interictal epileptiform discharges (IEDs) composed by the coactivity of both PV- and PV+ neurons, demonstrating that GABA transmission impedes its occurrence. Synchronous ensembles are clearly divided into two clusters one of them lasting longer and mainly composed by PV+ neurons. Because an ictal-like event was not recorded after several minutes of IEDs recording, it is inferred that an external stimulus and/or fast GABA transmission are necessary for its appearance, making this preparation ideal to study both the neuronal machinery to encode cortical spontaneous activity and its transformation into brief non-ictal epileptiform discharges.
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Affiliation(s)
- Miguel Serrano-Reyes
- División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México City 04510, Mexico
| | - Brisa García-Vilchis
- División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México City 04510, Mexico
| | - Rosa Reyes-Chapero
- División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México City 04510, Mexico
| | | | - Dagoberto Tapia
- División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México City 04510, Mexico
| | - Elvira Galarraga
- División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México City 04510, Mexico
| | - José Bargas
- División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México City 04510, Mexico.
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25
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Swaminathan A, Wichert I, Schmitz D, Maier N. Involvement of Mossy Cells in Sharp Wave-Ripple Activity In Vitro. Cell Rep 2019; 23:2541-2549. [PMID: 29847786 DOI: 10.1016/j.celrep.2018.04.095] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 01/31/2018] [Accepted: 04/23/2018] [Indexed: 12/31/2022] Open
Abstract
The role of mossy cells (MCs) of the hippocampal dentate area has long remained mysterious. Recent research has begun to unveil their significance in spatial computation of the hippocampus. Here, we used an in vitro model of sharp wave-ripple complexes (SWRs), which contribute to hippocampal memory formation, to investigate MC involvement in this fundamental population activity. We find that a significant fraction of MCs (∼47%) is recruited into the active neuronal network during SWRs in the CA3 area. Moreover, MCs receive pronounced, ripple-coherent, excitatory and inhibitory synaptic input. Finally, we find evidence for SWR-related synaptic activity in granule cells that is mediated by MCs. Given the widespread connectivity of MCs within and between hippocampi, our data suggest a role for MCs as a hub functionally coupling the CA3 and the DG during ripple-associated computations.
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Affiliation(s)
- Aarti Swaminathan
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Neuroscience Research Center, 10117 Berlin, Germany; Cluster of Excellence NeuroCure, 10117 Berlin, Germany
| | - Ines Wichert
- Bernstein Center for Computational Neuroscience Berlin, 10115 Berlin, Germany
| | - Dietmar Schmitz
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Neuroscience Research Center, 10117 Berlin, Germany; Bernstein Center for Computational Neuroscience Berlin, 10115 Berlin, Germany; Berlin Institute of Health, 10178 Berlin, Germany; Cluster of Excellence NeuroCure, 10117 Berlin, Germany; German Center for Neurodegenerative Diseases (DZNE) Berlin, 10117 Berlin, Germany; Einstein Center for Neurosciences Berlin, 10117 Berlin, Germany
| | - Nikolaus Maier
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Neuroscience Research Center, 10117 Berlin, Germany.
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26
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Kainate receptors have different modulatory effect in seizure-like events and slow rhythmic activity in entorhinal cortex ex vivo. Brain Res Bull 2019; 153:279-288. [PMID: 31550521 DOI: 10.1016/j.brainresbull.2019.09.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 09/16/2019] [Accepted: 09/18/2019] [Indexed: 11/22/2022]
Abstract
In the neocortex, neurons form functional networks, the members of which exhibit a variable degree of synchronization. Slow rhythmic activity may be regarded as a balanced interplay of excitatory and inhibitory neuronal network activity, which is essential in learning and memory consolidation. On the other hand, seizures may be considered as hypersynchronized network states occurring in epileptic diseases. The brain slice method and multi-electrode array (MEA) systems offer a good opportunity for the modelling of cortical spontaneous activities by examining their initiation and propagation. Our main goals were to characterise and compare spontaneous activities developing in different conditions and cortical network states. The role of kainate receptors in these processes was also tested. According to our results, there are demonstrable dissimilarities between slow rhythmic activities vs. seizure-like events developing in the rat entorhinal cortex ex vivo in normal vs. epileptic conditions. Propagation velocity, time scale, activity pattern and pharmacological sensitivity are all different. Kainate receptors play a role in network activity in entorhinal cortex, they are capable to prolong the duration of the events of epileptiform activity. Their regulatory effect is more prominent under epileptic than under normal conditions.
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27
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Li P, Geng X, Jiang H, Caccavano A, Vicini S, Wu JY. Measuring Sharp Waves and Oscillatory Population Activity With the Genetically Encoded Calcium Indicator GCaMP6f. Front Cell Neurosci 2019; 13:274. [PMID: 31275115 PMCID: PMC6593119 DOI: 10.3389/fncel.2019.00274] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 06/05/2019] [Indexed: 12/16/2022] Open
Abstract
GCaMP6f is among the most widely used genetically encoded calcium indicators for monitoring neuronal activity. Applications are at both the cellular and population levels. Here, we explore two important and under-explored issues. First, we have tested if GCaMP6f is sensitive enough for the detection of population activity with sparse firing, similar to the sensitivity of the local field potential (LFP). Second, we have tested if GCaMP6f is fast enough for the detection of fast network oscillations critical for the encoding and consolidation of memory. We have focused this study on the activity of the hippocampal network including sharp waves (SWs), carbachol-induced theta oscillations, and interictal-like spikes. We compare simultaneous LFP and optical GCaMP6f fluorescent recordings in Thy1-GCaMP6f mouse hippocampal slices. We observe that SWs produce a clear population GCaMP6f signal above noise with an average magnitude of 0.3% ΔF/F. This population signal is highly correlated with the LFP, albeit with a delay of 40.3 ms (SD 10.8 ms). The population GCaMP6f signal follows the LFP evoked by 20 Hz stimulation with high fidelity, while electrically evoked oscillations up to 40 Hz were detectable with reduced amplitude. GCaMP6f and LFP signals showed a large amplitude discrepancy. The amplitude of GCaMP6f fluorescence increased by a factor of 28.9 (SD 13.5) between spontaneous SWs and carbachol-induced theta bursts, while the LFP amplitude increased by a factor of 2.4 (SD 1.0). Our results suggest that GCaMP6f is a useful tool for applications commonly considered beyond the scope of genetically encoded calcium indicators. In particular, population GCaMP6f signals are sensitive enough for detecting synchronous network events with sparse firing and sub-threshold activity, as well as asynchronous events with only a nominal LFP. In addition, population GCaMP6f signals are fast enough for monitoring theta and beta oscillations (<25 Hz). Faster calcium indicators (e.g., GCaMP7) will further improve the frequency response for the detection of gamma band oscillations. The advantage of population optical over LFP recordings are that they are non-contact and free from stimulation artifacts. These features may be particularly useful for high-throughput recordings and applications sensitive to stimulus artifact, such as monitoring responses during continuous stimulation.
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Affiliation(s)
- Pinggan Li
- Department of Pediatric Neurology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
- Department of Neuroscience, Georgetown University, Washington, DC, United States
| | - Xinling Geng
- Department of Neuroscience, Georgetown University, Washington, DC, United States
- School of Biomedical Engineering, Capital Medical University, Beijing, China
| | - Huiyi Jiang
- Department of Neuroscience, Georgetown University, Washington, DC, United States
- Department of Pediatrics, The First Hospital of Jilin University, Changchun, China
| | - Adam Caccavano
- Department of Pharmacology and Physiology, Georgetown University, Washington, DC, United States
| | - Stefano Vicini
- Department of Pharmacology and Physiology, Georgetown University, Washington, DC, United States
| | - Jian-young Wu
- Department of Neuroscience, Georgetown University, Washington, DC, United States
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28
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Magloire V, Cornford J, Lieb A, Kullmann DM, Pavlov I. KCC2 overexpression prevents the paradoxical seizure-promoting action of somatic inhibition. Nat Commun 2019; 10:1225. [PMID: 30874549 PMCID: PMC6420604 DOI: 10.1038/s41467-019-08933-4] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Accepted: 02/01/2019] [Indexed: 11/09/2022] Open
Abstract
Although cortical interneurons are apparently well-placed to suppress seizures, several recent reports have highlighted a paradoxical role of perisomatic-targeting parvalbumin-positive (PV+) interneurons in ictogenesis. Here, we use an acute in vivo model of focal cortical seizures in awake behaving mice, together with closed-loop optogenetic manipulation of PV+ interneurons, to investigate their function during seizures. We show that photo-depolarization of PV+ interneurons rapidly switches from an anti-ictal to a pro-ictal effect within a few seconds of seizure initiation. The pro-ictal effect of delayed photostimulation of PV+ interneurons was not shared with dendrite-targeting somatostatin-positive (SOM+) interneurons. We also show that this switch can be prevented by overexpression of the neuronal potassium-chloride co-transporter KCC2 in principal cortical neurons. These results suggest that strategies aimed at improving the ability of principal neurons to maintain a trans-membrane chloride gradient in the face of excessive network activity can prevent interneurons from contributing to seizure perpetuation.
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Affiliation(s)
- Vincent Magloire
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, University College London, London, WC1N 3BG, UK.
| | - Jonathan Cornford
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Andreas Lieb
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Dimitri M Kullmann
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Ivan Pavlov
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, University College London, London, WC1N 3BG, UK.
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29
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Magloire V, Mercier MS, Kullmann DM, Pavlov I. GABAergic Interneurons in Seizures: Investigating Causality With Optogenetics. Neuroscientist 2018; 25:344-358. [PMID: 30317911 PMCID: PMC6745605 DOI: 10.1177/1073858418805002] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Seizures are complex pathological network events characterized by excessive and
hypersynchronized activity of neurons, including a highly diverse population of
GABAergic interneurons. Although the primary function of inhibitory interneurons
under normal conditions is to restrain excitation in the brain, this system
appears to fail intermittently, allowing runaway excitation. Recent developments
in optogenetics, combined with genetic tools and advanced electrophysiological
and imaging techniques, allow us for the first time to assess the causal roles
of identified cell-types in network dynamics. While these methods have greatly
increased our understanding of cortical microcircuits in epilepsy, the roles
played by individual GABAergic cell-types in controlling ictogenesis remain
incompletely resolved. Indeed, the ability of interneurons to suppress epileptic
discharges varies across different subtypes, and an accumulating body of
evidence paradoxically implicates some interneuron subtypes in the initiation
and maintenance of epileptiform activity. Here, we bring together findings from
this growing field and discuss what can be inferred regarding the causal role of
different GABAergic cell-types in seizures.
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Affiliation(s)
- Vincent Magloire
- Department of Clinical and Experimental Epilepsy, Institute of Neurology, UCL, London, UK
| | - Marion S Mercier
- Department of Clinical and Experimental Epilepsy, Institute of Neurology, UCL, London, UK
| | - Dimitri M Kullmann
- Department of Clinical and Experimental Epilepsy, Institute of Neurology, UCL, London, UK
| | - Ivan Pavlov
- Department of Clinical and Experimental Epilepsy, Institute of Neurology, UCL, London, UK
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30
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Takács VT, Cserép C, Schlingloff D, Pósfai B, Szőnyi A, Sos KE, Környei Z, Dénes Á, Gulyás AI, Freund TF, Nyiri G. Co-transmission of acetylcholine and GABA regulates hippocampal states. Nat Commun 2018; 9:2848. [PMID: 30030438 PMCID: PMC6054650 DOI: 10.1038/s41467-018-05136-1] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 06/12/2018] [Indexed: 12/13/2022] Open
Abstract
The basal forebrain cholinergic system is widely assumed to control cortical functions via non-synaptic transmission of a single neurotransmitter. Yet, we find that mouse hippocampal cholinergic terminals invariably establish GABAergic synapses, and their cholinergic vesicles dock at those synapses only. We demonstrate that these synapses do not co-release but co-transmit GABA and acetylcholine via different vesicles, whose release is triggered by distinct calcium channels. This co-transmission evokes composite postsynaptic potentials, which are mutually cross-regulated by presynaptic autoreceptors. Although postsynaptic cholinergic receptor distribution cannot be investigated, their response latencies suggest a focal, intra- and/or peri-synaptic localisation, while GABAA receptors are detected intra-synaptically. The GABAergic component alone effectively suppresses hippocampal sharp wave-ripples and epileptiform activity. Therefore, the differentially regulated GABAergic and cholinergic co-transmission suggests a hitherto unrecognised level of control over cortical states. This novel model of hippocampal cholinergic neurotransmission may lead to alternative pharmacotherapies after cholinergic deinnervation seen in neurodegenerative disorders.
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Affiliation(s)
- Virág T Takács
- Laboratory of Cerebral Cortex Research Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u 43, Budapest, 1083, Hungary
| | - Csaba Cserép
- Laboratory of Cerebral Cortex Research Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u 43, Budapest, 1083, Hungary.,Momentum Laboratory of Neuroimmunology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u 43, Budapest, 1083, Hungary
| | - Dániel Schlingloff
- Laboratory of Cerebral Cortex Research Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u 43, Budapest, 1083, Hungary.,János Szentágothai Doctoral School of Neurosciences, Semmelweis University, Budapest, 1085, Hungary
| | - Balázs Pósfai
- Laboratory of Cerebral Cortex Research Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u 43, Budapest, 1083, Hungary
| | - András Szőnyi
- Laboratory of Cerebral Cortex Research Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u 43, Budapest, 1083, Hungary.,János Szentágothai Doctoral School of Neurosciences, Semmelweis University, Budapest, 1085, Hungary
| | - Katalin E Sos
- Laboratory of Cerebral Cortex Research Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u 43, Budapest, 1083, Hungary.,János Szentágothai Doctoral School of Neurosciences, Semmelweis University, Budapest, 1085, Hungary
| | - Zsuzsanna Környei
- Momentum Laboratory of Neuroimmunology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u 43, Budapest, 1083, Hungary
| | - Ádám Dénes
- Momentum Laboratory of Neuroimmunology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u 43, Budapest, 1083, Hungary
| | - Attila I Gulyás
- Laboratory of Cerebral Cortex Research Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u 43, Budapest, 1083, Hungary
| | - Tamás F Freund
- Laboratory of Cerebral Cortex Research Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u 43, Budapest, 1083, Hungary
| | - Gábor Nyiri
- Laboratory of Cerebral Cortex Research Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u 43, Budapest, 1083, Hungary.
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31
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Lévesque M, Chen LY, Hamidi S, Avoli M. Dynamic interneuron-principal cell interplay leads to a specific pattern of in vitro ictogenesis. Neurobiol Dis 2018; 115:92-100. [PMID: 29635022 DOI: 10.1016/j.nbd.2018.04.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 03/12/2018] [Accepted: 04/04/2018] [Indexed: 01/20/2023] Open
Abstract
Ictal discharges induced by 4-aminopyridine in the in vitro rodent entorhinal cortex present with either low-voltage fast or sudden onset patterns. The role of interneurons in initiating low-voltage fast onset ictal discharges is well established but the processes leading to sudden onset ictal discharges remain unclear. We analysed here the participation of interneurons (n = 75) and principal cells (n = 13) in the sudden onset pattern by employing in vitro tetrode wire recordings in the entorhinal cortex of brain slices from Sprague-Dawley rats. Ictal discharges emerged from a background of frequently occurring interictal spikes that were associated to a specific interneuron/principal cell interplay. High rates of interneuron firing occurred 12 ms before interictal spike onset while principal cells fired later during low interneuron firing. In contrast, the onset of sudden ictal discharges was characterized by increased firing from principal cells 627 ms before ictal onset whereas interneurons increased their firing rates 161 ms before ictal onset. Our data show that sudden onset ictogenesis is associated with frequently occurring interictal spikes resting on the interplay between interneurons and principal cells while ictal discharges stem from enhanced principal cell firing leading to increased interneuron activity. These findings indicate that specific patterns of interactions between interneurons and principal cells shape interictal and ictal discharges with sudden onset in the rodent entorhinal cortex. We propose that specific neuronal interactions lead to the generation of distinct onset patterns in focal epileptic disorders.
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Affiliation(s)
- Maxime Lévesque
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 University Street, Montréal, H3A 2B4, Qc, Canada
| | - Li-Yuan Chen
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 University Street, Montréal, H3A 2B4, Qc, Canada
| | - Shabnam Hamidi
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 University Street, Montréal, H3A 2B4, Qc, Canada
| | - Massimo Avoli
- Department of Neurology and Neurosurgery and Department of Physiology, McGill University, 3801 University Street, Montréal, H3A 2B4, Qc, Canada.
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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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33
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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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Mechanisms for Selective Single-Cell Reactivation during Offline Sharp-Wave Ripples and Their Distortion by Fast Ripples. Neuron 2017. [PMID: 28641116 DOI: 10.1016/j.neuron.2017.05.032] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Memory traces are reactivated selectively during sharp-wave ripples. The mechanisms of selective reactivation, and how degraded reactivation affects memory, are poorly understood. We evaluated hippocampal single-cell activity during physiological and pathological sharp-wave ripples using juxtacellular and intracellular recordings in normal and epileptic rats with different memory abilities. CA1 pyramidal cells participate selectively during physiological events but fired together during epileptic fast ripples. We found that firing selectivity was dominated by an event- and cell-specific synaptic drive, modulated in single cells by changes in the excitatory/inhibitory ratio measured intracellularly. This mechanism collapses during pathological fast ripples to exacerbate and randomize neuronal firing. Acute administration of a use- and cell-type-dependent sodium channel blocker reduced neuronal collapse and randomness and improved recall in epileptic rats. We propose that cell-specific synaptic inputs govern firing selectivity of CA1 pyramidal cells during sharp-wave ripples.
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35
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Jiruska P, Alvarado-Rojas C, Schevon CA, Staba R, Stacey W, Wendling F, Avoli M. Update on the mechanisms and roles of high-frequency oscillations in seizures and epileptic disorders. Epilepsia 2017; 58:1330-1339. [PMID: 28681378 DOI: 10.1111/epi.13830] [Citation(s) in RCA: 115] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/29/2017] [Indexed: 12/11/2022]
Abstract
High-frequency oscillations (HFOs) are a type of brain activity that is recorded from brain regions capable of generating seizures. Because of the close association of HFOs with epileptogenic tissue and ictogenesis, understanding their cellular and network mechanisms could provide valuable information about the organization of epileptogenic networks and how seizures emerge from the abnormal activity of these networks. In this review, we summarize the most recent advances in the field of HFOs and provide a critical evaluation of new observations within the context of already established knowledge. Recent improvements in recording technology and the introduction of optogenetics into epilepsy research have intensified experimental work on HFOs. Using advanced computer models, new cellular substrates of epileptic HFOs were identified and the role of specific neuronal subtypes in HFO genesis was determined. Traditionally, the pathogenesis of HFOs was explored mainly in patients with temporal lobe epilepsy and in animal models mimicking this condition. HFOs have also been reported to occur in other epileptic disorders and models such as neocortical epilepsy, genetically determined epilepsies, and infantile spasms, which further support the significance of HFOs in the pathophysiology of epilepsy. It is increasingly recognized that HFOs are generated by multiple mechanisms at both the cellular and network levels. Future studies on HFOs combining novel high-resolution in vivo imaging techniques and precise control of neuronal behavior using optogenetics or chemogenetics will provide evidence about the causal role of HFOs in seizures and epileptogenesis. Detailed understanding of the pathophysiology of HFOs will propel better HFO classification and increase their information yield for clinical and diagnostic purposes.
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Affiliation(s)
- Premysl Jiruska
- Department of Developmental Epileptology, Institute of Physiology, The Czech Academy of Sciences, Prague, Czech Republic
| | | | | | - Richard Staba
- Department of Neurology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, U.S.A
| | - William Stacey
- Department of Neurology, Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, U.S.A
| | - Fabrice Wendling
- Laboratory of Signal and Image Processing, INSERM U1099, Rennes, France.,Laboratoire de Traitement du Signal et de l'Image, University of Rennes 1, Rennes, France
| | - Massimo Avoli
- Montreal Neurological Institute and Departments of Neurology & Neurosurgery and of Physiology, McGill University, Montréal, Québec, Canada.,Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
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36
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Kim CM, Nykamp DQ. The influence of depolarization block on seizure-like activity in networks of excitatory and inhibitory neurons. J Comput Neurosci 2017; 43:65-79. [PMID: 28528529 DOI: 10.1007/s10827-017-0647-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Revised: 03/11/2017] [Accepted: 04/26/2017] [Indexed: 11/29/2022]
Abstract
The inhibitory restraint necessary to suppress aberrant activity can fail when inhibitory neurons cease to generate action potentials as they enter depolarization block. We investigate possible bifurcation structures that arise at the onset of seizure-like activity resulting from depolarization block in inhibitory neurons. Networks of conductance-based excitatory and inhibitory neurons are simulated to characterize different types of transitions to the seizure state, and a mean field model is developed to verify the generality of the observed phenomena of excitatory-inhibitory dynamics. Specifically, the inhibitory population's activation function in the Wilson-Cowan model is modified to be non-monotonic to reflect that inhibitory neurons enter depolarization block given strong input. We find that a physiological state and a seizure state can coexist, where the seizure state is characterized by high excitatory and low inhibitory firing rate. Bifurcation analysis of the mean field model reveals that a transition to the seizure state may occur via a saddle-node bifurcation or a homoclinic bifurcation. We explain the hysteresis observed in network simulations using these two bifurcation types. We also demonstrate that extracellular potassium concentration affects the depolarization block threshold; the consequent changes in bifurcation structure enable the network to produce the tonic to clonic phase transition observed in biological epileptic networks.
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Affiliation(s)
- Christopher M Kim
- School of Mathematics, University of Minnesota, Minneapolis, MN, USA. .,Laboratory of Biological Modeling, NIDDK, National Institute of Health, Bethesda, MD, USA.
| | - Duane Q Nykamp
- School of Mathematics, University of Minnesota, Minneapolis, MN, USA
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37
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Altered Oscillatory Dynamics of CA1 Parvalbumin Basket Cells during Theta-Gamma Rhythmopathies of Temporal Lobe Epilepsy. eNeuro 2016; 3:eN-NWR-0284-16. [PMID: 27896315 PMCID: PMC5114702 DOI: 10.1523/eneuro.0284-16.2016] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 10/25/2016] [Accepted: 10/25/2016] [Indexed: 12/23/2022] Open
Abstract
Recent reports in human demonstrate a role of theta–gamma coupling in memory for spatial episodes and a lack of coupling in people experiencing temporal lobe epilepsy, but the mechanisms are unknown. Using multisite silicon probe recordings of epileptic rats engaged in episodic-like object recognition tasks, we sought to evaluate the role of theta–gamma coupling in the absence of epileptiform activities. Our data reveal a specific association between theta–gamma (30–60 Hz) coupling at the proximal stratum radiatum of CA1 and spatial memory deficits. We targeted the microcircuit mechanisms with a novel approach to identify putative interneuronal types in tetrode recordings (parvalbumin basket cells in particular) and validated classification criteria in the epileptic context with neurochemical identification of intracellularly recorded cells. In epileptic rats, putative parvalbumin basket cells fired poorly modulated at the falling theta phase, consistent with weaker inputs from Schaffer collaterals and attenuated gamma oscillations, as evaluated by theta-phase decomposition of current–source density signals. We propose that theta–gamma interneuronal rhythmopathies of the temporal lobe are intimately related to episodic memory dysfunction in this condition.
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38
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Morris G, Jiruska P, Jefferys JGR, Powell AD. A New Approach of Modified Submerged Patch Clamp Recording Reveals Interneuronal Dynamics during Epileptiform Oscillations. Front Neurosci 2016; 10:519. [PMID: 27881950 PMCID: PMC5101843 DOI: 10.3389/fnins.2016.00519] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 10/26/2016] [Indexed: 01/22/2023] Open
Abstract
HighlightsSimultaneous epileptiform LFPs and single-cell activity can be recorded in the membrane chamber. Interneuron firing can be linked to epileptiform high frequency activity. Fast ripples, unique to chronic epilepsy, can be modeled in ex vivo tissue from TeNT-treated rats.
Traditionally, visually-guided patch clamp in brain slices using submerged recording conditions has been required to characterize the activity of individual neurons. However, due to limited oxygen availability, submerged conditions truncate fast network oscillations including epileptiform activity. Thus, it is technically challenging to study the contribution of individual identified neurons to fast network activity. The membrane chamber is a submerged-style recording chamber, modified to enhance oxygen supply to the slice, which we use to demonstrate the ability to record single-cell activity during in vitro epilepsy. We elicited epileptiform activity using 9 mM potassium and simultaneously recorded from fluorescently labeled interneurons. Epileptiform discharges were more reliable than in standard submerged conditions. During these synchronous discharges interneuron firing frequency increased and action potential amplitude progressively decreased. The firing of 15 interneurons was significantly correlated with epileptiform high frequency activity (HFA; ~100–500 Hz) cycles. We also recorded epileptiform activity in tissue prepared from chronically epileptic rats, treated with intrahippocampal tetanus neurotoxin. Four of these slices generated fast ripple activity, unique to chronic epilepsy. We showed the membrane chamber is a promising new in vitro environment facilitating patch clamp recordings in acute epilepsy models. Further, we showed that chronic epilepsy can be better modeled using ex vivo brain slices. These findings demonstrate that the membrane chamber facilitates previously challenging investigations into the neuronal correlates of epileptiform activity in vitro.
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Affiliation(s)
- Gareth Morris
- Neuronal Networks Group, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham Birmingham, UK
| | - Premysl Jiruska
- Department of Developmental Epileptology, Institute of Physiology, Czech Academy of Sciences Prague, Czechia
| | - John G R Jefferys
- Neuronal Networks Group, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham Birmingham, UK
| | - Andrew D Powell
- Neuronal Networks Group, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham Birmingham, UK
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39
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Gulyás AI, Freund TF, Káli S. The Effects of Realistic Synaptic Distribution and 3D Geometry on Signal Integration and Extracellular Field Generation of Hippocampal Pyramidal Cells and Inhibitory Neurons. Front Neural Circuits 2016; 10:88. [PMID: 27877113 PMCID: PMC5099150 DOI: 10.3389/fncir.2016.00088] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 10/17/2016] [Indexed: 12/02/2022] Open
Abstract
In vivo and in vitro multichannel field and somatic intracellular recordings are frequently used to study mechanisms of network pattern generation. When interpreting these data, neurons are often implicitly considered as electrotonically compact cylinders with a homogeneous distribution of excitatory and inhibitory inputs. However, the actual distributions of dendritic length, diameter, and the densities of excitatory and inhibitory input are non-uniform and cell type-specific. We first review quantitative data on the dendritic structure and synaptic input and output distribution of pyramidal cells (PCs) and interneurons in the hippocampal CA1 area. Second, using multicompartmental passive models of four different types of neurons, we quantitatively explore the effect of differences in dendritic structure and synaptic distribution on the errors and biases of voltage clamp measurements of inhibitory and excitatory postsynaptic currents. Finally, using the 3-dimensional distribution of dendrites and synaptic inputs we calculate how different inhibitory and excitatory inputs contribute to the generation of local field potential in the hippocampus. We analyze these effects at different realistic background activity levels as synaptic bombardment influences neuronal conductance and thus the propagation of signals in the dendritic tree. We conclude that, since dendrites are electrotonically long and entangled in 3D, somatic intracellular and field potential recordings miss the majority of dendritic events in some cell types, and thus overemphasize the importance of perisomatic inhibitory inputs and belittle the importance of complex dendritic processing. Modeling results also suggest that PCs and inhibitory neurons probably use different input integration strategies. In PCs, second- and higher-order thin dendrites are relatively well-isolated from each other, which may support branch-specific local processing as suggested by studies of active dendritic integration. In the electrotonically compact parvalbumin- and cholecystokinincontaining interneurons, synaptic events are visible in the whole dendritic arbor, and thus the entire dendritic tree may form a single integrative element. Calretinin-containing interneurons were found to be electrotonically extended, which suggests the possibility of complex dendritic processing in this cell type. Our results also highlight the need for the integration of methods that allow the measurement of dendritic processes into studies of synaptic interactions and dynamics in neural networks.
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Affiliation(s)
- Attila I Gulyás
- Laboratory of Cerebral Cortex Research, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary
| | - Tamás F Freund
- Laboratory of Cerebral Cortex Research, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary
| | - Szabolcs Káli
- Laboratory of Cerebral Cortex Research, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary
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40
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Kohus Z, Káli S, Rovira‐Esteban L, Schlingloff D, Papp O, Freund TF, Hájos N, Gulyás AI. Properties and dynamics of inhibitory synaptic communication within the CA3 microcircuits of pyramidal cells and interneurons expressing parvalbumin or cholecystokinin. J Physiol 2016; 594:3745-74. [PMID: 27038232 PMCID: PMC4929320 DOI: 10.1113/jp272231] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 03/21/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS To understand how a network operates, its elements must be identified and characterized, and the interactions of the elements need to be studied in detail. In the present study, we describe quantitatively the connectivity of two classes of inhibitory neurons in the hippocampal CA3 area (parvalbumin-positive and cholecystokinin-positive interneurons), a key region for the generation of behaviourally relevant synchronous activity patterns. We describe how interactions among these inhibitory cells and their local excitatory target neurons evolve over the course of physiological and pathological activity patterns. The results of the present study enable the construction of precise neuronal network models that may help us understand how network dynamics is generated and how it can underlie information processing and pathological conditions in the brain. We show how inhibitory dynamics between parvalbumin-positive basket cells and pyramidal cells could contribute to sharp wave-ripple generation. ABSTRACT Different hippocampal activity patterns are determined primarily by the interaction of excitatory cells and different types of interneurons. To understand the mechanisms underlying the generation of different network dynamics, the properties of synaptic transmission need to be uncovered. Perisomatic inhibition is critical for the generation of sharp wave-ripples, gamma oscillations and pathological epileptic activities. Therefore, we aimed to quantitatively and systematically characterize the temporal properties of the synaptic transmission between perisomatic inhibitory neurons and pyramidal cells in the CA3 area of mouse hippocampal slices, using action potential patterns recorded during physiological and pathological network states. Parvalbumin-positive (PV+) and cholecystokinin-positive (CCK+) interneurons showed distinct intrinsic physiological features. Interneurons of the same type formed reciprocally connected subnetworks, whereas the connectivity between interneuron classes was sparse. The characteristics of unitary interactions depended on the identity of both synaptic partners, whereas the short-term plasticity of synaptic transmission depended mainly on the presynaptic cell type. PV+ interneurons showed frequency-dependent depression, whereas more complex dynamics characterized the output of CCK+ interneurons. We quantitatively captured the dynamics of transmission at these different types of connection with simple mathematical models, and describe in detail the response to physiological and pathological discharge patterns. Our data suggest that the temporal propeties of PV+ interneuron transmission may contribute to sharp wave-ripple generation. These findings support the view that intrinsic and synaptic features of PV+ cells make them ideally suited for the generation of physiological network oscillations, whereas CCK+ cells implement a more subtle, graded control in the hippocampus.
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Affiliation(s)
- Z. Kohus
- Institute of Experimental MedicineHungarian Academy of SciencesBudapestHungary
- János Szentágothai, PhD Program of Semmelweis UniversityBudapestHungary
| | - S. Káli
- Institute of Experimental MedicineHungarian Academy of SciencesBudapestHungary
- Péter Pázmány Catholic UniversityFaculty of Information TechnologyBudapestHungary
| | - L. Rovira‐Esteban
- Institute of Experimental MedicineHungarian Academy of SciencesBudapestHungary
| | - D. Schlingloff
- Institute of Experimental MedicineHungarian Academy of SciencesBudapestHungary
- János Szentágothai, PhD Program of Semmelweis UniversityBudapestHungary
| | - O. Papp
- Institute of Experimental MedicineHungarian Academy of SciencesBudapestHungary
| | - T. F. Freund
- Institute of Experimental MedicineHungarian Academy of SciencesBudapestHungary
- Péter Pázmány Catholic UniversityFaculty of Information TechnologyBudapestHungary
| | - N. Hájos
- Institute of Experimental MedicineHungarian Academy of SciencesBudapestHungary
| | - A. I. Gulyás
- Institute of Experimental MedicineHungarian Academy of SciencesBudapestHungary
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Ramani M, Mylvaganam S, Krawczyk M, Wang L, Zoidl C, Brien J, Reynolds JN, Kapur B, Poulter MO, Zoidl G, Carlen PL. Differential expression of astrocytic connexins in a mouse model of prenatal alcohol exposure. Neurobiol Dis 2016; 91:83-93. [DOI: 10.1016/j.nbd.2016.02.022] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 01/11/2016] [Accepted: 02/29/2016] [Indexed: 11/24/2022] Open
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Krawczyk M, Ramani M, Dian J, Florez CM, Mylvaganam S, Brien J, Reynolds J, Kapur B, Zoidl G, Poulter MO, Carlen PL. Hippocampal hyperexcitability in fetal alcohol spectrum disorder: Pathological sharp waves and excitatory/inhibitory synaptic imbalance. Exp Neurol 2016; 280:70-9. [PMID: 26996134 DOI: 10.1016/j.expneurol.2016.03.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2015] [Revised: 02/29/2016] [Accepted: 03/13/2016] [Indexed: 01/01/2023]
Abstract
Prenatal alcohol exposure (PAE) can lead to long-lasting neurological alterations that may predispose individuals to seizures and neurobehavioral dysfunction. To date, there exists limited information regarding the underlying pathophysiological mechanisms. The hippocampal CA3 region generates excitatory population activity, called sharp waves (SPWs), that provide an ideal model to study perturbations in neuronal excitability at the network and cellular levels. In the present study, we utilized a mouse model of PAE and used dual extracellular and whole-cell patch-clamp recordings from CA3 hippocampal pyramidal cells to evaluate the effect of 1st trimester-equivalent ethanol exposure (10% v/v) on SPW activity and excitatory/inhibitory balance. We observed that PAE significantly altered in vitro SPW waveforms, with an increased duration and amplitude, when compared to controls. In addition, PAE slices exhibited reduced pharmacological inhibition by the GABA-A receptor antagonist bicuculline (BMI) on SPW activity, and increased population spike paired-pulse ratios, all indicative of network disinhibition within the PAE hippocampus. Evaluation of PAE CA3 pyramidal cell activity associated with SPWs, revealed increased action potential cell firing, which was accompanied by an imbalance of excitatory/inhibitory synaptic drive, shifted in favor of excitation. Moreover, we observed intrinsic changes in CA3 pyramidal activity in PAE animals, including increased burst firing and instantaneous firing rate. This is the first study to provide evidence for hippocampal dysfunction in the ability to maintain network homeostasis and underlying cellular hyperexcitability in a model of PAE. These circuit and cellular level alterations may contribute to the increased propensity for seizures and neurobehavioral dysfunction observed in patients with a history of PAE.
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Affiliation(s)
- Michal Krawczyk
- Division of Fundamental Neurobiology, Toronto Western Research Institute, UHN, Toronto, ON, Canada.
| | - Meera Ramani
- Division of Fundamental Neurobiology, Toronto Western Research Institute, UHN, Toronto, ON, Canada
| | - Josh Dian
- Division of Fundamental Neurobiology, Toronto Western Research Institute, UHN, Toronto, ON, Canada
| | - Carlos M Florez
- Division of Fundamental Neurobiology, Toronto Western Research Institute, UHN, Toronto, ON, Canada
| | - Shanthini Mylvaganam
- Division of Fundamental Neurobiology, Toronto Western Research Institute, UHN, Toronto, ON, Canada
| | - James Brien
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada
| | - James Reynolds
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada
| | - Bhushan Kapur
- Division of Clinical Pharmacology & Toxicology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Georg Zoidl
- Department of Biology, York University, Toronto, ON, Canada; Department of Psychology, York University, Toronto, ON, Canada
| | - Michael O Poulter
- Robarts Research Institute and Department of Physiology and Pharmacology, University of Western Ontario, London, ON, Canada
| | - Peter L Carlen
- Division of Fundamental Neurobiology, Toronto Western Research Institute, UHN, Toronto, ON, Canada; Department of Medicine (Neurology), University of Toronto, Toronto, ON, Canada; Department of Physiology, University of Toronto, Toronto, ON, Canada
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Abstract
Pathological high-frequency oscillations (HFOs) (80-800 Hz) are considered biomarkers of epileptogenic tissue, but the underlying complex neuronal events are not well understood. Here, we identify and discuss several outstanding issues or conundrums in regards to the recording, analysis, and interpretation of HFOs in the epileptic brain to critically highlight what is known and what is not about these enigmatic events. High-frequency oscillations reflect a range of neuronal processes contributing to overlapping frequencies from the lower 80 Hz to the very fast spectral frequency bands. Given their complex neuronal nature, HFOs are extremely sensitive to recording conditions and analytical approaches. We provide a list of recommendations that could help to obtain comparable HFO signals in clinical and basic epilepsy research. Adopting basic standards will facilitate data sharing and interpretation that collectively will aid in understanding the role of HFOs in health and disease for translational purpose.
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Wykes RC, Kullmann DM, Pavlov I, Magloire V. Optogenetic approaches to treat epilepsy. J Neurosci Methods 2016; 260:215-20. [DOI: 10.1016/j.jneumeth.2015.06.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Revised: 06/03/2015] [Accepted: 06/04/2015] [Indexed: 02/06/2023]
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Diversity of sharp-wave-ripple LFP signatures reveals differentiated brain-wide dynamical events. Proc Natl Acad Sci U S A 2015; 112:E6379-87. [PMID: 26540729 DOI: 10.1073/pnas.1518257112] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Sharp-wave-ripple (SPW-R) complexes are believed to mediate memory reactivation, transfer, and consolidation. However, their underlying neuronal dynamics at multiple scales remains poorly understood. Using concurrent hippocampal local field potential (LFP) recordings and functional MRI (fMRI), we study local changes in neuronal activity during SPW-R episodes and their brain-wide correlates. Analysis of the temporal alignment between SPW and ripple components reveals well-differentiated SPW-R subtypes in the CA1 LFP. SPW-R-triggered fMRI maps show that ripples aligned to the positive peak of their SPWs have enhanced neocortical metabolic up-regulation. In contrast, ripples occurring at the trough of their SPWs relate to weaker neocortical up-regulation and absent subcortical down-regulation, indicating differentiated involvement of neuromodulatory pathways in the ripple phenomenon mediated by long-range interactions. To our knowledge, this study provides the first evidence for the existence of SPW-R subtypes with differentiated CA1 activity and metabolic correlates in related brain areas, possibly serving different memory functions.
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Tóth E, Fabó D, Entz L, Ulbert I, Erőss L. Intracranial neuronal ensemble recordings and analysis in epilepsy. J Neurosci Methods 2015; 260:261-9. [PMID: 26453987 DOI: 10.1016/j.jneumeth.2015.09.028] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 09/25/2015] [Accepted: 09/28/2015] [Indexed: 11/30/2022]
Abstract
Pathological neuronal firing was demonstrated 50 years ago as the hallmark of epileptically transformed cortex with the use of implanted microelectrodes. Since then, microelectrodes remained only experimental tools in humans to detect unitary neuronal activity to reveal physiological and pathological brain functions. This recording technique has evolved substantially in the past few decades; however, based on recent human data implying their usefulness as diagnostic tools, we expect a substantial increase in the development of microelectrodes in the near future. Here, we review the technological background and history of microelectrode array development for human examinations in epilepsy, including discussions on of wire-based and microelectrode arrays fabricated using micro-electro-mechanical system (MEMS) techniques and novel future techniques to record neuronal ensemble. We give an overview of clinical and surgical considerations, and try to provide a list of probes on the market with their availability for human recording. Then finally, we briefly review the literature on modulation of single neuron for the treatment of epilepsy, and highlight the current topics under examination that can be background for the future development.
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Affiliation(s)
- Emília Tóth
- Epilepsy Centrum, National Institute of Clinical Neurosciences, Budapest, Hungary; Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary
| | - Dániel Fabó
- Epilepsy Centrum, National Institute of Clinical Neurosciences, Budapest, Hungary.
| | - László Entz
- Department of Functional Neurosurgery, National Institute of Clinical Neurosciences, Budapest, Hungary
| | - István Ulbert
- Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary; Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - Loránd Erőss
- Department of Functional Neurosurgery, National Institute of Clinical Neurosciences, Budapest, Hungary
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Buzsáki G. Hippocampal sharp wave-ripple: A cognitive biomarker for episodic memory and planning. Hippocampus 2015; 25:1073-188. [PMID: 26135716 PMCID: PMC4648295 DOI: 10.1002/hipo.22488] [Citation(s) in RCA: 922] [Impact Index Per Article: 102.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 06/30/2015] [Indexed: 12/23/2022]
Abstract
Sharp wave ripples (SPW-Rs) represent the most synchronous population pattern in the mammalian brain. Their excitatory output affects a wide area of the cortex and several subcortical nuclei. SPW-Rs occur during "off-line" states of the brain, associated with consummatory behaviors and non-REM sleep, and are influenced by numerous neurotransmitters and neuromodulators. They arise from the excitatory recurrent system of the CA3 region and the SPW-induced excitation brings about a fast network oscillation (ripple) in CA1. The spike content of SPW-Rs is temporally and spatially coordinated by a consortium of interneurons to replay fragments of waking neuronal sequences in a compressed format. SPW-Rs assist in transferring this compressed hippocampal representation to distributed circuits to support memory consolidation; selective disruption of SPW-Rs interferes with memory. Recently acquired and pre-existing information are combined during SPW-R replay to influence decisions, plan actions and, potentially, allow for creative thoughts. In addition to the widely studied contribution to memory, SPW-Rs may also affect endocrine function via activation of hypothalamic circuits. Alteration of the physiological mechanisms supporting SPW-Rs leads to their pathological conversion, "p-ripples," which are a marker of epileptogenic tissue and can be observed in rodent models of schizophrenia and Alzheimer's Disease. Mechanisms for SPW-R genesis and function are discussed in this review.
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Affiliation(s)
- György Buzsáki
- The Neuroscience Institute, School of Medicine and Center for Neural Science, New York University, New York, New York
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48
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Bellone JA, Rudobeck E, Hartman RE, Szücs A, Vlkolinský R. A Single Low Dose of Proton Radiation Induces Long-Term Behavioral and Electrophysiological Changes in Mice. Radiat Res 2015. [DOI: 10.1667/rr13903.1] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Florez CM, Lukankin V, Sugumar S, McGinn R, Zhang ZJ, Zhang L, Carlen PL. Hypoglycemia-induced alterations in hippocampal intrinsic rhythms: Decreased inhibition, increased excitation, seizures and spreading depression. Neurobiol Dis 2015; 82:213-225. [PMID: 26093168 DOI: 10.1016/j.nbd.2015.06.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2014] [Revised: 06/09/2015] [Accepted: 06/12/2015] [Indexed: 12/16/2022] Open
Abstract
UNLABELLED Seizures are the most common clinical presentation of severe hypoglycemia, usually as a side effect of insulin treatment for juvenile onset type 1 diabetes mellitus and advanced type 2 diabetes. We used the mouse thick hippocampal slice preparation to study the pathophysiology of hypoglycemia-induced seizures and the effects of severe glucose depletion on the isolated hippocampal rhythms from the CA3 circuitry. METHODS AND RESULTS Dropping the glucose perfusate concentration from the standard 10 mM to 1 mM produced epileptiform activity in 14/16 of the slices. Seizure-like events (SLEs) originated in the CA3 region and then spread into the CA1 region. Following the SLE, a spreading-depression (SD)-like event occurred (12/16 slices) with irreversible synaptic failure in the CA1 region (8/12 slices). CA3 SD-like events followed ~30 s after the SD-like event in the CA1 region. Less commonly, SD-like events originated in the CA3 region (4/12). Additionally, prior to the onset of the SLE in the CA3 area, there was decreased GABA correlated baseline SPW activity (bSPW), while there was increased large-amplitude sharp wave (LASW) activity, thought to originate from synchronous pyramidal cell firing. CA3 pyramidal cells displayed progressive tonic depolarization prior to the seizure which was resistant to synaptic transmission blockade. The initiation of hypoglycemic seizures and SD was prevented by AMPA/kainate or NMDA receptor blockade. CONCLUSIONS Severe glucose depletion induces rapid changes initiated in the intrinsic CA3 rhythms of the hippocampus including depressed inhibition and enhanced excitation, which may underlie the mechanisms of seizure generation and delayed spreading depression.
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Affiliation(s)
- C M Florez
- Departments of Medicine (Neurology) and Physiology, University of Toronto, Toronto, Canada; Division of Fundamental Neurobiology, TWRI, UHN, Toronto, Canada
| | - V Lukankin
- Departments of Medicine (Neurology) and Physiology, University of Toronto, Toronto, Canada
| | - S Sugumar
- Departments of Medicine (Neurology) and Physiology, University of Toronto, Toronto, Canada
| | - R McGinn
- Departments of Medicine (Neurology) and Physiology, University of Toronto, Toronto, Canada
| | - Z J Zhang
- Departments of Medicine (Neurology) and Physiology, University of Toronto, Toronto, Canada
| | - L Zhang
- Departments of Medicine (Neurology) and Physiology, University of Toronto, Toronto, Canada
| | - P L Carlen
- Departments of Medicine (Neurology) and Physiology, University of Toronto, Toronto, Canada; Division of Fundamental Neurobiology, TWRI, UHN, Toronto, Canada.
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Network Mechanisms Generating Abnormal and Normal Hippocampal High-Frequency Oscillations: A Computational Analysis. eNeuro 2015; 2. [PMID: 26146658 PMCID: PMC4487885 DOI: 10.1523/eneuro.0024-15.2015] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
High-frequency oscillations (HFOs) are an intriguing potential biomarker for epilepsy, typically categorized according to peak frequency as either ripples (100–250 Hz) or fast ripples (>250 Hz). In the hippocampus, fast ripples were originally thought to be more specific to epileptic tissue, but it is still very difficult to distinguish which HFOs are caused by normal versus pathological brain activity. In this study, we use a computational model of hippocampus to investigate possible network mechanisms underpinning normal ripples, pathological ripples, and fast ripples. Our results unify several prior findings regarding HFO mechanisms, and also make several new predictions regarding abnormal HFOs. We show that HFOs are generic, emergent phenomena whose characteristics reflect a wide range of connectivity and network input. Although produced by different mechanisms, both normal and abnormal HFOs generate similar ripple frequencies, underscoring that peak frequency is unable to distinguish the two. Abnormal ripples are generic phenomena that arise when input to pyramidal cells overcomes network inhibition, resulting in high-frequency, uncoordinated firing. In addition, fast ripples transiently and sporadically arise from the precise conditions that produce abnormal ripples. Lastly, we show that such abnormal conditions do not require any specific network structure to produce coherent HFOs, as even completely asynchronous activity is capable of producing abnormal ripples and fast ripples in this manner. These results provide a generic, network-based explanation for the link between pathological ripples and fast ripples, and a unifying description for the entire spectrum from normal ripples to pathological fast ripples.
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