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Nasretdinov A, Vinokurova D, Lemale CL, Burkhanova-Zakirova G, Chernova K, Makarova J, Herreras O, Dreier JP, Khazipov R. Diversity of cortical activity changes beyond depression during Spreading Depolarizations. Nat Commun 2023; 14:7729. [PMID: 38007508 PMCID: PMC10676372 DOI: 10.1038/s41467-023-43509-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 11/10/2023] [Indexed: 11/27/2023] Open
Abstract
Spreading depolarizations (SDs) are classically thought to be associated with spreading depression of cortical activity. Here, we found that SDs in patients with subarachnoid hemorrhage produce variable, ranging from depression to booming, changes in electrocorticographic activity, especially in the delta frequency band. In rats, depression of activity was characteristic of high-potassium-induced full SDs, whereas partial superficial SDs caused either little change or a boom of activity at the cortical vertex, supported by volume conduction of signals from spared delta generators in the deep cortical layers. Partial SDs also caused moderate neuronal depolarization and sustained excitation, organized in gamma oscillations in a narrow sub-SD zone. Thus, our study challenges the concept of homology between spreading depolarization and spreading depression by showing that SDs produce variable, from depression to booming, changes in activity at the cortical surface and in different cortical layers depending on the depth of SD penetration.
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Affiliation(s)
- Azat Nasretdinov
- Laboratory of Neurobiology, Kazan Federal University, Kazan, 420008, Russia
| | - Daria Vinokurova
- Laboratory of Neurobiology, Kazan Federal University, Kazan, 420008, Russia
- INMED-INSERM, Aix-Marseille University, Marseille, 13273, France
| | - Coline L Lemale
- Centre for Stroke Research Berlin, Department of Experimental Neurology and Department of Neurology, Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, D-10117, Berlin, Germany
| | | | - Ksenia Chernova
- Laboratory of Neurobiology, Kazan Federal University, Kazan, 420008, Russia
| | - Julia Makarova
- Department of Translational Neuroscience, Cajal Institute-CSIC, Madrid, Spain
| | - Oscar Herreras
- Department of Translational Neuroscience, Cajal Institute-CSIC, Madrid, Spain
| | - Jens P Dreier
- Centre for Stroke Research Berlin, Department of Experimental Neurology and Department of Neurology, Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, D-10117, Berlin, Germany
- Bernstein Centre for Computational Neuroscience Berlin, D-10115, Berlin, Germany
- Einstein Centre for Neurosciences Berlin, D-10117, Berlin, Germany
| | - Roustem Khazipov
- Laboratory of Neurobiology, Kazan Federal University, Kazan, 420008, Russia.
- INMED-INSERM, Aix-Marseille University, Marseille, 13273, France.
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2
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Tadres D, Wong PH, To T, Moehlis J, Louis M. Depolarization block in olfactory sensory neurons expands the dimensionality of odor encoding. SCIENCE ADVANCES 2022; 8:eade7209. [PMID: 36525486 PMCID: PMC9757753 DOI: 10.1126/sciadv.ade7209] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 11/15/2022] [Indexed: 05/20/2023]
Abstract
Upon strong and prolonged excitation, neurons can undergo a silent state called depolarization block that is often associated with disorders such as epileptic seizures. Here, we show that neurons in the peripheral olfactory system undergo depolarization block as part of their normal physiological function. Typically, olfactory sensory neurons enter depolarization block at odor concentrations three orders of magnitude above their detection threshold, thereby defining receptive fields over concentration bands. The silencing of high-affinity olfactory sensory neurons produces sparser peripheral odor representations at high-odor concentrations, which might facilitate perceptual discrimination. Using a conductance-based model of the olfactory transduction cascade paired with spike generation, we provide numerical and experimental evidence that depolarization block arises from the slow inactivation of sodium channels-a process that could affect a variety of sensory neurons. The existence of ethologically relevant depolarization block in olfactory sensory neurons creates an additional dimension that expands the peripheral encoding of odors.
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Affiliation(s)
- David Tadres
- Department of Molecular, Cellular, and Developmental Biology and Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA, USA
- Department of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | - Philip H. Wong
- Department of Molecular, Cellular, and Developmental Biology and Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA, USA
- Department of Mechanical Engineering, University of California, Santa Barbara, Santa Barbara, CA, USA
| | - Thuc To
- Department of Molecular, Cellular, and Developmental Biology and Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA, USA
| | - Jeff Moehlis
- Department of Mechanical Engineering, University of California, Santa Barbara, Santa Barbara, CA, USA
| | - Matthieu Louis
- Department of Molecular, Cellular, and Developmental Biology and Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA, USA
- Department of Physics, University of California, Santa Barbara, Santa Barbara, CA, USA
- Corresponding author.
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3
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Gentiletti D, de Curtis M, Gnatkovsky V, Suffczynski P. Focal seizures are organized by feedback between neural activity and ion concentration changes. eLife 2022; 11:68541. [PMID: 35916367 PMCID: PMC9377802 DOI: 10.7554/elife.68541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 07/12/2022] [Indexed: 11/13/2022] Open
Abstract
Human and animal EEG data demonstrate that focal seizures start with low-voltage fast activity, evolve into rhythmic burst discharges and are followed by a period of suppressed background activity. This suggests that processes with dynamics in the range of tens of seconds govern focal seizure evolution. We investigate the processes associated with seizure dynamics by complementing the Hodgkin-Huxley mathematical model with the physical laws that dictate ion movement and maintain ionic gradients. Our biophysically realistic computational model closely replicates the electrographic pattern of a typical human focal seizure characterized by low voltage fast activity onset, tonic phase, clonic phase and postictal suppression. Our study demonstrates, for the first time in silico, the potential mechanism of seizure initiation by inhibitory interneurons via the initial build-up of extracellular K+ due to intense interneuronal spiking. The model also identifies ionic mechanisms that may underlie a key feature in seizure dynamics, i.e., progressive slowing down of ictal discharges towards the end of seizure. Our model prediction of specific scaling of inter-burst intervals is confirmed by seizure data recorded in the whole guinea pig brain in vitro and in humans, suggesting that the observed termination pattern may hold across different species. Our results emphasize ionic dynamics as elementary processes behind seizure generation and indicate targets for new therapeutic strategies.
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Wienbar S, Schwartz GW. Differences in spike generation instead of synaptic inputs determine the feature selectivity of two retinal cell types. Neuron 2022; 110:2110-2123.e4. [PMID: 35508174 DOI: 10.1016/j.neuron.2022.04.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 03/21/2022] [Accepted: 04/11/2022] [Indexed: 12/19/2022]
Abstract
Retinal ganglion cells (RGCs) are the spiking projection neurons of the eye that encode different features of the visual environment. The circuits providing synaptic input to different RGC types to drive feature selectivity have been studied extensively, but there has been less research aimed at understanding the intrinsic properties and how they impact feature selectivity. We introduce an RGC type in the mouse, the Bursty Suppressed-by-Contrast (bSbC) RGC, and compared it to the OFF sustained alpha (OFFsA). Differences in their contrast response functions arose from differences not in synaptic inputs but in their intrinsic properties. Spike generation was the key intrinsic property behind this functional difference; the bSbC RGC undergoes depolarization block while the OFFsA RGC maintains a high spike rate. Our results demonstrate that differences in intrinsic properties allow these two RGC types to detect and relay distinct features of an identical visual stimulus to the brain.
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Affiliation(s)
- Sophia Wienbar
- Department of Ophthalmology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Northwestern University Interdepartmental Neuroscience Program, Northwestern University, Evanston, IL 60208, USA
| | - Gregory William Schwartz
- Department of Ophthalmology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Department of Neurobiology, Weinberg College of Arts and Sciences, Northwestern University, Evanston, IL 60208, USA.
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5
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Fábera P, Uttl L, Kubová H, Tsenov G, Mareš P. Adenosine Kinase Isoforms in the Developing Rat Hippocampus after LiCl/Pilocarpine Status Epilepticus. Int J Mol Sci 2022; 23:ijms23052510. [PMID: 35269653 PMCID: PMC8910300 DOI: 10.3390/ijms23052510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 02/21/2022] [Accepted: 02/22/2022] [Indexed: 01/27/2023] Open
Abstract
LiCl/pilocarpine status epilepticus (SE) induced in immature rats leads, after a latent period, to hippocampal hyperexcitability. The excitability may be influenced by adenosine, which exhibits anticonvulsant activity. The concentration of adenosine is regulated by adenosine kinase (ADK) present in two isoforms—ADK-L and ADK-S. The main goal of the study is to elucidate the changes in ADK isoform expression after LiCl/pilocarpine SE and whether potential changes, as well as inhibition of ADK by 5-iodotubercidin (5-ITU), may contribute to changes in hippocampal excitability during brain development. LiCl/pilocarpine SE was elicited in 12-day-old rats. Hippocampal excitability in immature rats was studied by the model of hippocampal afterdischarges (ADs), in which we demonstrated the potential inhibitory effect of 5-ITU. ADs demonstrated significantly decreased hippocampal excitability 3 days after SE induction, whereas significant hyperexcitability after 20 days compared to controls was shown. 5-ITU administration showed its inhibitory effect on the ADs in 32-day-old SE rats compared to SE rats without 5-ITU. Moreover, both ADK isoforms were examined in the immature rat hippocampus. The ADK-L isoform demonstrated significantly decreased expression in 12-day-old SE rats compared to the appropriate naïve rats, whereas increased ADK-S isoform expression was revealed. A decreasing ADK-L/-S ratio showed the declining dominance of ADK-L isoform during early brain development. LiCl/pilocarpine SE increased the excitability of the hippocampus 20 days after SE induction. The ADK inhibitor 5-ITU exhibited anticonvulsant activity at the same age. Age-related differences in hippocampal excitability after SE might correspond to the development of ADK isoform levels in the hippocampus.
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Affiliation(s)
- Petr Fábera
- Department of Developmental Epileptology, Institute of Physiology, Czech Academy of Sciences, 14200 Prague, Czech Republic; (L.U.); (H.K.); (G.T.); (P.M.)
- Department of Neurology, Second Faculty of Medicine, Motol University Hospital, Charles University, 15006 Prague, Czech Republic
- Correspondence: ; Tel.: +42-073-272-8308; Fax: +42-022-443-6875
| | - Libor Uttl
- Department of Developmental Epileptology, Institute of Physiology, Czech Academy of Sciences, 14200 Prague, Czech Republic; (L.U.); (H.K.); (G.T.); (P.M.)
- National Institute of Mental Health, 25067 Klecany, Czech Republic
| | - Hana Kubová
- Department of Developmental Epileptology, Institute of Physiology, Czech Academy of Sciences, 14200 Prague, Czech Republic; (L.U.); (H.K.); (G.T.); (P.M.)
| | - Grygoriy Tsenov
- Department of Developmental Epileptology, Institute of Physiology, Czech Academy of Sciences, 14200 Prague, Czech Republic; (L.U.); (H.K.); (G.T.); (P.M.)
- National Institute of Mental Health, 25067 Klecany, Czech Republic
| | - Pavel Mareš
- Department of Developmental Epileptology, Institute of Physiology, Czech Academy of Sciences, 14200 Prague, Czech Republic; (L.U.); (H.K.); (G.T.); (P.M.)
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6
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Arboit A, Krautwald K, Angenstein F. The cholinergic system modulates negative BOLD responses in the prefrontal cortex once electrical perforant pathway stimulation triggers neuronal afterdischarges in the hippocampus. J Cereb Blood Flow Metab 2022; 42:364-380. [PMID: 34590894 PMCID: PMC8795231 DOI: 10.1177/0271678x211049820] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Repeated high-frequency pulse-burst stimulations of the rat perforant pathway elicited positive BOLD responses in the right hippocampus, septum and prefrontal cortex. However, when the first stimulation period also triggered neuronal afterdischarges in the hippocampus, then a delayed negative BOLD response in the prefrontal cortex was generated. While neuronal activity and cerebral blood volume (CBV) increased in the hippocampus during the period of hippocampal neuronal afterdischarges (h-nAD), CBV decreased in the prefrontal cortex, although neuronal activity did not decrease. Only after termination of h-nAD did CBV in the prefrontal cortex increase again. Thus, h-nAD triggered neuronal activity in the prefrontal cortex that counteracted the usual neuronal activity-related functional hyperemia. This process was significantly enhanced by pilocarpine, a mACh receptor agonist, and completely blocked when pilocarpine was co-administered with scopolamine, a mACh receptor antagonist. Scopolamine did not prevent the formation of the negative BOLD response, thus mACh receptors modulate the strength of the negative BOLD response.
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Affiliation(s)
- Alberto Arboit
- Functional Imaging Group, Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Magdeburg, Germany
| | - Karla Krautwald
- Functional Imaging Group, Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Magdeburg, Germany
| | - Frank Angenstein
- Functional Imaging Group, Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Magdeburg, Germany.,Leibniz Institute for Neurobiology (LIN), Magdeburg, Germany.,Medical Faculty, Otto von Guericke University, Magdeburg, Germany
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7
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A unified physiological framework of transitions between seizures, sustained ictal activity and depolarization block at the single neuron level. J Comput Neurosci 2022; 50:33-49. [PMID: 35031915 PMCID: PMC8818009 DOI: 10.1007/s10827-022-00811-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 11/10/2021] [Accepted: 01/03/2022] [Indexed: 10/29/2022]
Abstract
The majority of seizures recorded in humans and experimental animal models can be described by a generic phenomenological mathematical model, the Epileptor. In this model, seizure-like events (SLEs) are driven by a slow variable and occur via saddle node (SN) and homoclinic bifurcations at seizure onset and offset, respectively. Here we investigated SLEs at the single cell level using a biophysically relevant neuron model including a slow/fast system of four equations. The two equations for the slow subsystem describe ion concentration variations and the two equations of the fast subsystem delineate the electrophysiological activities of the neuron. Using extracellular K+ as a slow variable, we report that SLEs with SN/homoclinic bifurcations can readily occur at the single cell level when extracellular K+ reaches a critical value. In patients and experimental models, seizures can also evolve into sustained ictal activity (SIA) and depolarization block (DB), activities which are also parts of the dynamic repertoire of the Epileptor. Increasing extracellular concentration of K+ in the model to values found during experimental status epilepticus and DB, we show that SIA and DB can also occur at the single cell level. Thus, seizures, SIA, and DB, which have been first identified as network events, can exist in a unified framework of a biophysical model at the single neuron level and exhibit similar dynamics as observed in the Epileptor.Author Summary: Epilepsy is a neurological disorder characterized by the occurrence of seizures. Seizures have been characterized in patients in experimental models at both macroscopic and microscopic scales using electrophysiological recordings. Experimental works allowed the establishment of a detailed taxonomy of seizures, which can be described by mathematical models. We can distinguish two main types of models. Phenomenological (generic) models have few parameters and variables and permit detailed dynamical studies often capturing a majority of activities observed in experimental conditions. But they also have abstract parameters, making biological interpretation difficult. Biophysical models, on the other hand, use a large number of variables and parameters due to the complexity of the biological systems they represent. Because of the multiplicity of solutions, it is difficult to extract general dynamical rules. In the present work, we integrate both approaches and reduce a detailed biophysical model to sufficiently low-dimensional equations, and thus maintaining the advantages of a generic model. We propose, at the single cell level, a unified framework of different pathological activities that are seizures, depolarization block, and sustained ictal activity.
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8
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Arboit A, Ku SP, Krautwald K, Angenstein F. Brief neuronal afterdischarges in the rat hippocampus lead to transient changes in oscillatory activity and to a very long-lasting decline in BOLD signals without inducing a hypoxic state. Neuroimage 2021; 245:118769. [PMID: 34861394 DOI: 10.1016/j.neuroimage.2021.118769] [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: 09/22/2021] [Revised: 11/24/2021] [Accepted: 11/29/2021] [Indexed: 10/19/2022] Open
Abstract
The effects of hippocampal neuronal afterdischarges (nAD) on hemodynamic parameters, such as blood-oxygen-level-dependent (BOLD) signals) and local cerebral blood volume (CBV) changes, as well as neuronal activity and metabolic parameters in the dentate gyrus, was investigated in rats by combining in vivo electrophysiology with functional magnetic resonance imaging (fMRI) or 1H-nuclear magnetic resonance spectroscopy (1H-NMRS). Brief electrical high-frequency pulse-burst stimulation of the right perforant pathway triggered nAD, a seizure-like activity, in the right dentate gyrus with a high incidence, a phenomenon that in turn caused a sustained decrease in BOLD signals for more than 30 min. The decrease was associated with a reduction in CBV but not with signs of hypoxic metabolism. nAD also triggered transient changes mainly in the low gamma frequency band that recovered within 20 min, so that the longer-lasting altered hemodynamics reflected a switch in blood supply rather than transient changes in ongoing neuronal activity. Even in the presence of reduced baseline BOLD signals, neurovascular coupling mechanisms remained intact, making long-lasting vasospasm unlikely. Subsequently generated nAD did not further alter the baseline BOLD signals. Similarly, nAD did not alter baseline BOLD signals when acetaminophen was previously administered, because acetaminophen alone had already caused a similar decrease in baseline BOLD signals as observed after the first nAD. Thus, at least two different blood supply states exist for the hippocampus, one low and one high, with both states allowing similar neuronal activity. Both acetaminophen and nAD switch from the high to the low blood supply state. As a result, the hemodynamic response function to an identical stimulus differed after nAD or acetaminophen, although the triggered neuronal activity was similar.
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Affiliation(s)
- Alberto Arboit
- Functional Neuroimaging Group, Deutsches Zentrum für neurodegenerative Erkrankungen (DZNE), Leipzigerstr, 44, Magdeburg 39118, Germany
| | - Shih-Pi Ku
- Department Functional Architecture of Memory, Leibniz Institute for Neurobiology (LIN), Magdeburg 39118, Germany
| | - Karla Krautwald
- Functional Neuroimaging Group, Deutsches Zentrum für neurodegenerative Erkrankungen (DZNE), Leipzigerstr, 44, Magdeburg 39118, Germany
| | - Frank Angenstein
- Functional Neuroimaging Group, Deutsches Zentrum für neurodegenerative Erkrankungen (DZNE), Leipzigerstr, 44, Magdeburg 39118, Germany; Department Functional Architecture of Memory, Leibniz Institute for Neurobiology (LIN), Magdeburg 39118, Germany; Center for Behavior and Brain Sciences (CBBS), Magdeburg, Germany; Medical Faculty, Otto von Guericke University, Magdeburg 39118, Germany.
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9
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Huang W, Ke Y, Zhu J, Liu S, Cong J, Ye H, Guo Y, Wang K, Zhang Z, Meng W, Gao TM, Luhmann HJ, Kilb W, Chen R. TRESK channel contributes to depolarization-induced shunting inhibition and modulates epileptic seizures. Cell Rep 2021; 36:109404. [PMID: 34289346 DOI: 10.1016/j.celrep.2021.109404] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 03/19/2021] [Accepted: 06/23/2021] [Indexed: 11/18/2022] Open
Abstract
Glutamatergic and GABAergic synaptic transmission controls excitation and inhibition of postsynaptic neurons, whereas activity of ion channels modulates neuronal intrinsic excitability. However, it is unclear how excessive neuronal excitation affects intrinsic inhibition to regain homeostatic stability under physiological or pathophysiological conditions. Here, we report that a seizure-like sustained depolarization can induce short-term inhibition of hippocampal CA3 neurons via a mechanism of membrane shunting. This depolarization-induced shunting inhibition (DShI) mediates a non-synaptic, but neuronal intrinsic, short-term plasticity that is able to suppress action potential generation and postsynaptic responses by activated ionotropic receptors. We demonstrate that the TRESK channel significantly contributes to DShI. Disruption of DShI by genetic knockout of TRESK exacerbates the sensitivity and severity of epileptic seizures of mice, whereas overexpression of TRESK attenuates seizures. In summary, these results uncover a type of homeostatic intrinsic plasticity and its underlying mechanism. TRESK might represent a therapeutic target for antiepileptic drugs.
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Affiliation(s)
- Weiyuan Huang
- Guangdong Province Key Laboratory of Psychiatric Disorders, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Yue Ke
- Guangdong Province Key Laboratory of Psychiatric Disorders, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Jianping Zhu
- Guangdong Province Key Laboratory of Psychiatric Disorders, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Shuai Liu
- Guangdong Province Key Laboratory of Psychiatric Disorders, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Jin Cong
- Guangdong Province Key Laboratory of Psychiatric Disorders, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Hailin Ye
- Guangdong Province Key Laboratory of Psychiatric Disorders, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Yanwu Guo
- The National Key Clinic Specialty, The Engineering Technology Research Center of Education Ministry of China, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Department of Neurosurgery, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China
| | - Kewan Wang
- Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Zhenhai Zhang
- State Key Laboratory of Organ Failure Research, National Clinical Research Center for Kidney Disease, Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China; Department of Bioinformatics, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China; Center for Precision Medicine, Guangzhou First People's Hospital, School of Medicine, South China University of Technology, Guangzhou 510030, China; Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Southern Medical University, Guangzhou 510515, China
| | - Wenxiang Meng
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Tian-Ming Gao
- Guangdong Province Key Laboratory of Psychiatric Disorders, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China; Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Southern Medical University, Guangzhou 510515, China; State Key Laboratory of Organ Failure Research, Collaborative Innovation Center for Brain Science, Southern Medical University, Guangzhou 510515, China
| | - Heiko J Luhmann
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University Mainz, Duesbergweg 6, Mainz 55120, Germany
| | - Werner Kilb
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University Mainz, Duesbergweg 6, Mainz 55120, Germany.
| | - Rongqing Chen
- Guangdong Province Key Laboratory of Psychiatric Disorders, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China; The National Key Clinic Specialty, The Engineering Technology Research Center of Education Ministry of China, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Department of Neurosurgery, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China; Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Southern Medical University, Guangzhou 510515, China.
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10
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Tamim I, Chung DY, de Morais AL, Loonen ICM, Qin T, Misra A, Schlunk F, Endres M, Schiff SJ, Ayata C. Spreading depression as an innate antiseizure mechanism. Nat Commun 2021; 12:2206. [PMID: 33850125 PMCID: PMC8044138 DOI: 10.1038/s41467-021-22464-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 03/15/2021] [Indexed: 12/16/2022] Open
Abstract
Spreading depression (SD) is an intense and prolonged depolarization in the central nervous systems from insect to man. It is implicated in neurological disorders such as migraine and brain injury. Here, using an in vivo mouse model of focal neocortical seizures, we show that SD may be a fundamental defense against seizures. Seizures induced by topical 4-aminopyridine, penicillin or bicuculline, or systemic kainic acid, culminated in SDs at a variable rate. Greater seizure power and area of recruitment predicted SD. Once triggered, SD immediately suppressed the seizure. Optogenetic or KCl-induced SDs had similar antiseizure effect sustained for more than 30 min. Conversely, pharmacologically inhibiting SD occurrence during a focal seizure facilitated seizure generalization. Altogether, our data indicate that seizures trigger SD, which then terminates the seizure and prevents its generalization.
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Affiliation(s)
- Isra Tamim
- Neurovascular Research Unit, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
- Charité-Universitätsmedizin Berlin, Klinik und Hochschulambulanz für Neurologie und Centrum für Schlaganfallforschung Berlin (CSB), Berlin, Germany
| | - David Y Chung
- Neurovascular Research Unit, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Andreia Lopes de Morais
- Neurovascular Research Unit, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Inge C M Loonen
- Neurovascular Research Unit, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Tao Qin
- Neurovascular Research Unit, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Amrit Misra
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Frieder Schlunk
- Charité-Universitätsmedizin Berlin, Klinik und Hochschulambulanz für Neurologie und Centrum für Schlaganfallforschung Berlin (CSB), Berlin, Germany
| | - Matthias Endres
- Charité-Universitätsmedizin Berlin, Klinik und Hochschulambulanz für Neurologie und Centrum für Schlaganfallforschung Berlin (CSB), Berlin, Germany
| | - Steven J Schiff
- Center for Neural Engineering, Departments of Engineering Science and Mechanics and Physics, The Pennsylvania State University, State College, PA, USA
| | - Cenk Ayata
- Neurovascular Research Unit, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
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11
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Different effects of monophasic pulses and biphasic pulses applied by a bipolar stimulation electrode in the rat hippocampal CA1 region. Biomed Eng Online 2021; 20:25. [PMID: 33750406 PMCID: PMC7942171 DOI: 10.1186/s12938-021-00862-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Accepted: 03/01/2021] [Indexed: 11/10/2022] Open
Abstract
Background Electrical pulse stimulations have been applied in brain for treating certain diseases such as movement disorders. High-frequency stimulations (HFS) of biphasic pulses have been used in clinic stimulations, such as deep brain stimulation (DBS), to minimize the risk of tissue damages caused by the electrical stimulations. However, HFS sequences of monophasic pulses have often been used in animal experiments for studying neuronal responses to the stimulations. It is not clear yet what the differences of the neuronal responses to the HFS of monophasic pulses from the HFS of biphasic pulses are. Methods To investigate the neuronal responses to the two types of pulses, orthodromic-HFS (O-HFS) and antidromic-HFS (A-HFS) of biphasic and monophasic pulses (1-min) were delivered by bipolar electrodes, respectively, to the Schaffer collaterals (i.e., afferent fibers) and the alveus fibers (i.e., efferent fibers) of the rat hippocampal CA1 region in vivo. Evoked population spikes of CA1 pyramidal neurons to the HFSs were recorded in the CA1 region. In addition, single pulses of antidromic- and orthodromic-test stimuli were applied before and after HFSs to evaluate the baseline and the recovery of neuronal activity, respectively. Results Spreading depression (SD) appeared during sequences of 200-Hz monophasic O-HFS with a high incidence (4/5), but did not appear during corresponding 200-Hz biphasic O-HFS (0/6). A preceding burst of population spikes appeared before the SD waveforms. Then, the SD propagated slowly, silenced neuronal firing temporarily and resulted in partial recovery of orthodromically evoked population spikes (OPS) after the end of O-HFS. No SD events appeared during the O-HFS with a lower frequency of 100 Hz of monophasic or biphasic pulses (0/5 and 0/6, respectively), neither during the A-HFS of 200-Hz pulses (0/9). The antidromically evoked population spikes (APS) after 200-Hz biphasic A-HFS recovered to baseline level within ~ 2 min. However, the APS only recovered partially after the 200-Hz A-HFS of monophasic pulses. Conclusions The O-HFS with a higher frequency of monophasic pulses can induce the abnormal neuron activity of SD and the A-HFS of monophasic pulses can cause a persisting attenuation of neuronal excitability, indicating neuronal damages caused by monophasic stimulations in brain tissues. The results provide guidance for proper stimulation protocols in clinic and animal experiments.
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Nuñez A, Buño W. The Theta Rhythm of the Hippocampus: From Neuronal and Circuit Mechanisms to Behavior. Front Cell Neurosci 2021; 15:649262. [PMID: 33746716 PMCID: PMC7970048 DOI: 10.3389/fncel.2021.649262] [Citation(s) in RCA: 65] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 01/28/2021] [Indexed: 11/17/2022] Open
Abstract
This review focuses on the neuronal and circuit mechanisms involved in the generation of the theta (θ) rhythm and of its participation in behavior. Data have accumulated indicating that θ arises from interactions between medial septum-diagonal band of Broca (MS-DbB) and intra-hippocampal circuits. The intrinsic properties of MS-DbB and hippocampal neurons have also been shown to play a key role in θ generation. A growing number of studies suggest that θ may represent a timing mechanism to temporally organize movement sequences, memory encoding, or planned trajectories for spatial navigation. To accomplish those functions, θ and gamma (γ) oscillations interact during the awake state and REM sleep, which are considered to be critical for learning and memory processes. Further, we discuss that the loss of this interaction is at the base of various neurophatological conditions.
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Affiliation(s)
- Angel Nuñez
- Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina, Universidad Autonoma de Madrid, Madrid, Spain
| | - Washington Buño
- Instituto Cajal, Consejo Superior de Investigaciones Cientificas, Madrid, Spain
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13
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Hannan S, Aristovich K, Faulkner M, Avery J, Walker MC, Holder DS. Imaging slow brain activity during neocortical and hippocampal epileptiform events with electrical impedance tomography. Physiol Meas 2021; 42:014001. [PMID: 33361567 DOI: 10.1088/1361-6579/abd67a] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
OBJECTIVE Electrical impedance tomography (EIT) is an imaging technique that produces tomographic images of internal impedance changes within an object using surface electrodes. It can be used to image the slow increase in cerebral tissue impedance that occurs over seconds during epileptic seizures, which is attributed to cell swelling due to disturbances in ion homeostasis following hypersynchronous neuronal firing and its associated metabolic demands. In this study, we characterised and imaged this slow impedance response during neocortical and hippocampal epileptiform events in the rat brain and evaluated its relationship to the underlying neural activity. APPROACH Neocortical or hippocampal seizures, comprising repeatable series of high-amplitude ictal spikes, were induced by electrically stimulating the sensorimotor cortex or perforant path of rats anaesthetised with fentanyl-isoflurane. Transfer impedances were measured during ≥30 consecutive seizures, by applying a sinusoidal current through independent electrode pairs on an epicortical array, and combined to generate an EIT image of slow activity. MAIN RESULTS The slow impedance responses were consistently time-matched to the end of seizures and EIT images of this activity were reconstructed reproducibly in all animals (p < 0.03125, N = 5). These displayed foci of activity that were spatially confined to the facial somatosensory cortex and dentate gyrus for neocortical and hippocampal seizures, respectively, and encompassed a larger volume as the seizure progressed. Centre-of-mass analysis of reconstructions revealed that this activity corresponded to the true location of the epileptogenic zone, as determined by EEG recordings and fast neural EIT measurements which were obtained simultaneously. SIGNIFICANCE These findings suggest that the slow impedance response presents a reliable marker of hypersynchronous neuronal activity during epileptic seizures and can thus be utilised for investigating the mechanisms of epileptogenesis in vivo and for aiding localisation of the epileptogenic zone during presurgical evaluation of patients with refractory epilepsies.
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Affiliation(s)
- Sana Hannan
- Department of Medical Physics and Biomedical Engineering, University College London, United Kingdom
| | - Kirill Aristovich
- Department of Medical Physics and Biomedical Engineering, University College London, United Kingdom
| | - Mayo Faulkner
- Wolfson Institute for Biomedical Research, University College London, United Kingdom
| | - James Avery
- Department of Surgery and Cancer, Imperial College London, United Kingdom
| | - Matthew C Walker
- UCL Queen Square Institute of Neurology, University College London, United Kingdom
| | - David S Holder
- Department of Medical Physics and Biomedical Engineering, University College London, United Kingdom
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14
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Hannan S, Faulkner M, Aristovich K, Avery J, Walker MC, Holder DS. Optimised induction of on-demand focal hippocampal and neocortical seizures by electrical stimulation. J Neurosci Methods 2020; 346:108911. [DOI: 10.1016/j.jneumeth.2020.108911] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 08/10/2020] [Accepted: 08/12/2020] [Indexed: 11/25/2022]
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15
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Farrell JS, Colangeli R, Dudok B, Wolff MD, Nguyen SL, Jackson J, Dickson CT, Soltesz I, Teskey GC. In vivo assessment of mechanisms underlying the neurovascular basis of postictal amnesia. Sci Rep 2020; 10:14992. [PMID: 32929133 PMCID: PMC7490395 DOI: 10.1038/s41598-020-71935-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 08/21/2020] [Indexed: 12/16/2022] Open
Abstract
Long-lasting confusion and memory difficulties during the postictal state remain a major unmet problem in epilepsy that lacks pathophysiological explanation and treatment. We previously identified that long-lasting periods of severe postictal hypoperfusion/hypoxia, not seizures per se, are associated with memory impairment after temporal lobe seizures. While this observation suggests a key pathophysiological role for insufficient energy delivery, it is unclear how the networks that underlie episodic memory respond to vascular constraints that ultimately give rise to amnesia. Here, we focused on cellular/network level analyses in the CA1 of hippocampus in vivo to determine if neural activity, network oscillations, synaptic transmission, and/or synaptic plasticity are impaired following kindled seizures. Importantly, the induction of severe postictal hypoperfusion/hypoxia was prevented in animals treated by a COX-2 inhibitor, which experimentally separated seizures from their vascular consequences. We observed complete activation of CA1 pyramidal neurons during brief seizures, followed by a short period of reduced activity and flattening of the local field potential that resolved within minutes. During the postictal state, constituting tens of minutes to hours, we observed no changes in neural activity, network oscillations, and synaptic transmission. However, long-term potentiation of the temporoammonic pathway to CA1 was impaired in the postictal period, but only when severe local hypoxia occurred. Lastly, we tested the ability of rats to perform object-context discrimination, which has been proposed to require temporoammonic input to differentiate between sensory experience and the stored representation of the expected object-context pairing. Deficits in this task following seizures were reversed by COX-2 inhibition, which prevented severe postictal hypoxia. These results support a key role for hypoperfusion/hypoxia in postictal memory impairments and identify that many aspects of hippocampal network function are resilient during severe hypoxia except for long-term synaptic plasticity.
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Affiliation(s)
- Jordan S Farrell
- Department of Neurosurgery, Stanford University, Stanford, CA, USA.
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.
| | - Roberto Colangeli
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Barna Dudok
- Department of Neurosurgery, Stanford University, Stanford, CA, USA
| | - Marshal D Wolff
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Sarah L Nguyen
- Department of Psychology, University of Alberta, Edmonton, AB, Canada
| | - Jesse Jackson
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Clayton T Dickson
- Department of Psychology, University of Alberta, Edmonton, AB, Canada
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Ivan Soltesz
- Department of Neurosurgery, Stanford University, Stanford, CA, USA
| | - G Campbell Teskey
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
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16
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Hannan S, Faulkner M, Aristovich K, Avery J, Walker MC, Holder DS. In vivo imaging of deep neural activity from the cortical surface during hippocampal epileptiform events in the rat brain using electrical impedance tomography. Neuroimage 2020; 209:116525. [DOI: 10.1016/j.neuroimage.2020.116525] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 12/12/2019] [Accepted: 01/06/2020] [Indexed: 02/07/2023] Open
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17
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Zakharov A, Chernova K, Burkhanova G, Holmes GL, Khazipov R. Segregation of seizures and spreading depolarization across cortical layers. Epilepsia 2019; 60:2386-2397. [PMID: 31755112 DOI: 10.1111/epi.16390] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 10/25/2019] [Accepted: 10/25/2019] [Indexed: 01/13/2023]
Abstract
OBJECTIVE Cortical spreading depolarization (SD) and seizures are often co-occurring electrophysiological phenomena. However, the cross-layer dynamics of SD during seizures and the effect of SD on epileptic activity across cortical layers remain largely unknown. METHODS We explored the spatial-temporal dynamics of SD and epileptic activity across layers of the rat barrel cortex using direct current silicone probe recordings during flurothyl-induced seizures. RESULTS SD occurred in half of the flurothyl-evoked seizures. SD always started from the superficial layers and spread downward either through all cortical layers or stopping at the L4/L5 border. In cases without SD, seizures were characterized by synchronized population firing across all cortical layers throughout the entire seizure. However, when SD occurred, epileptic activity was transiently silenced in layers involved with SD but persisted in deeper layers. During partial SD, epileptiform activity persisted in deep layers throughout the entire seizure, with positive signals at the cortical surface reflecting passive sources of population spikes generated in deeper cortical layers. During full SD, the initial phase of SD propagation through the superficial layers was similar to partial SD, with suppression of activity at the superficial layers and segregation of seizures to deep layers. Further propagation of SD to deep layers resulted in a wave of transient suppression of epileptic activity through the entire cortical column. Thus, vertical propagation of SD through the cortical column creates dynamic network states during which epileptiform activity is restricted to layers without SD. SIGNIFICANCE Our results point to the importance of vertical SD spread in the SD-related depression of epileptiform activity across cortical layers.
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Affiliation(s)
- Andrey Zakharov
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia.,Department of physiology, Kazan State Medical University, Kazan, Russia
| | - Kseniya Chernova
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia
| | | | - Gregory L Holmes
- Department of Neurological Sciences, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Roustem Khazipov
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia.,Mediterranean Institute of Neurobiology, National Institute of Health and Medical Research Mixed Unit of Research 1249, Aix-Marseille University, Marseille, France
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18
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Fabera P, Parizkova M, Uttl L, Vondrakova K, Kubova H, Tsenov G, Mares P. Adenosine A1 Receptor Agonist 2-chloro-N6-cyclopentyladenosine and Hippocampal Excitability During Brain Development in Rats. Front Pharmacol 2019; 10:656. [PMID: 31258477 PMCID: PMC6587156 DOI: 10.3389/fphar.2019.00656] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Accepted: 05/20/2019] [Indexed: 01/10/2023] Open
Abstract
Objective: The adenosinergic system may influence excitability in the brain. Endogenous and exogenous adenosine has anticonvulsant activity presumably by activating A1 receptors. Adenosine A1 receptor agonist 2-chloro-N6-cyclopentyladenosine (CCPA) may thus bolster anticonvulsant effects, but its action and the number of A1 receptors at different developmental stages are not known. Methods: Hippocampal epileptic afterdischarges (ADs) were elicited in 12-, 15-, 18-, 25-, 45-, and 60-day-old rats. Stimulation and recording electrodes were implanted into the dorsal hippocampus. The A1 receptor agonist 2-chloro-N6-cyclopentyladenosine (CCPA, 0.5 or 1 mg/kg) was administered intraperitoneally 10 min before the first stimulation. Control animals were injected with saline. All rats were stimulated with a 2-s series of 1-ms biphasic pulses delivered at 60 Hz with increasing stepwise intensity (0.05–0.6 mA). Each age and dose group contained 9–14 animals. The AD thresholds and durations were evaluated, and the A1 receptors were detected in the hippocampus in 7-, 10-, 12-, 15-, 18-, 21-, 25-, 32-, and 52-day-old rats. Results: Both CCPA doses significantly increased hippocampal AD thresholds in 12-, 15-, 18-, and 60-day-old rats compared to controls. In contrast, the higher dose significantly decreased AD threshold in the 25-day-old rats. The AD durations were significantly shortened in all age groups except for 25-day-old rats where they were significantly prolonged. A1 receptor expression in the hippocampus was highest in 10-day-old rats and subsequently decreased. Significance: The adenosine A1 receptor agonist CCPA exhibited anticonvulsant activity at all developmental stages studied here except for 25-day-old rats. Age-related differences might be due to the development of presynaptic A1 receptors in the hippocampus.
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Affiliation(s)
- Petr Fabera
- Department of Developmental Epileptology, Institute of Physiology, Czech Academy of Sciences, Prague, Czechia.,Department of Neurology, Second Faculty of Medicine, Motol University Hospital, Charles University, Prague, Czechia
| | - Martina Parizkova
- Department of Developmental Epileptology, Institute of Physiology, Czech Academy of Sciences, Prague, Czechia.,Department of Neurology, Second Faculty of Medicine, Motol University Hospital, Charles University, Prague, Czechia
| | - Libor Uttl
- Department of Developmental Epileptology, Institute of Physiology, Czech Academy of Sciences, Prague, Czechia.,National Institute of Mental Health, Klecany, Czechia
| | - Katerina Vondrakova
- Department of Developmental Epileptology, Institute of Physiology, Czech Academy of Sciences, Prague, Czechia.,National Institute of Mental Health, Klecany, Czechia
| | - Hana Kubova
- Department of Developmental Epileptology, Institute of Physiology, Czech Academy of Sciences, Prague, Czechia
| | - Grygoriy Tsenov
- Department of Developmental Epileptology, Institute of Physiology, Czech Academy of Sciences, Prague, Czechia.,Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Pavel Mares
- Department of Developmental Epileptology, Institute of Physiology, Czech Academy of Sciences, Prague, Czechia
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Nasretdinov A, Lotfullina N, Vinokurova D, Lebedeva J, Burkhanova G, Chernova K, Zakharov A, Khazipov R. Direct Current Coupled Recordings of Cortical Spreading Depression Using Silicone Probes. Front Cell Neurosci 2017; 11:408. [PMID: 29311836 PMCID: PMC5742611 DOI: 10.3389/fncel.2017.00408] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 12/04/2017] [Indexed: 12/04/2022] Open
Abstract
Electrophysiological assessment of infraslow (<0.1 Hz) brain activities such as cortical spreading depression (SD), which occurs in a number of pathologies including migraine, epilepsy, traumatic brain injury (TBI) and brain ischemia requires direct current (DC) coupled recordings of local field potentials (LFPs). Here, we describe how DC-coupled recordings can be performed using high-density iridium electrode arrays (silicone probes). We found that the DC voltage offset of the silicone probe is large and often exceeds the amplifier input range. Introduction of an offset compensation chain at the signal ground efficiently minimized the DC offsets. Silicone probe DC-coupled recordings across layers of the rat visual and barrel cortices revealed that epipial application of KCl, dura incision or pinprick TBI induced SD which preferentially propagated through the supragranular layers and further spread to the granular and infragranular layers attaining maximal amplitudes of ~−30 mV in the infragranular layers. SD at the superficial cortical layers was nearly two-fold longer than at the deep cortical layers. Continuous epipial KCl evoked multiple recurrent SDs which always started in the supragranular layers but often failed to propagate through the deeper cortical layers. Intracortical KCl injection into the infragranular layers evoked SD which also started in the supragranular layers and spread to the granular and infragranular layers, further indicating that the supragranular layers are particularly prone to SD. Thus, DC-coupled recordings with silicone probes after offset compensation can be successfully used to explore the spatial—temporal dynamics of SD and other slow brain activities.
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Affiliation(s)
- Azat Nasretdinov
- Laboratory of Neurobiology, Department of Human and Animal Physiology, Kazan Federal University, Kazan, Russia
| | - Nailya Lotfullina
- Laboratory of Neurobiology, Department of Human and Animal Physiology, Kazan Federal University, Kazan, Russia
| | - Daria Vinokurova
- Laboratory of Neurobiology, Department of Human and Animal Physiology, Kazan Federal University, Kazan, Russia
| | - Julia Lebedeva
- Laboratory of Neurobiology, Department of Human and Animal Physiology, Kazan Federal University, Kazan, Russia
| | - Gulshat Burkhanova
- Laboratory of Neurobiology, Department of Human and Animal Physiology, Kazan Federal University, Kazan, Russia
| | - Kseniya Chernova
- Laboratory of Neurobiology, Department of Human and Animal Physiology, Kazan Federal University, Kazan, Russia
| | - Andrey Zakharov
- Laboratory of Neurobiology, Department of Human and Animal Physiology, Kazan Federal University, Kazan, Russia
| | - Roustem Khazipov
- Laboratory of Neurobiology, Department of Human and Animal Physiology, Kazan Federal University, Kazan, Russia.,Institut de Neurobiologie de la Méditerranée (INMED)-INSERM, UMR901, Aix-Marseille University, Marseille, France
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20
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Huang Y, Liu X, Wang G, Wang Y. SK channels participate in the formation of after burst hyperpolarization and partly inhibit the burst strength of epileptic ictal discharges. Mol Med Rep 2017; 17:1762-1774. [PMID: 29257204 PMCID: PMC5780121 DOI: 10.3892/mmr.2017.8068] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 10/16/2017] [Indexed: 01/03/2023] Open
Abstract
Epilepsy is a common disease of the central nervous system. Tetanic spasms and convulsions are the key symptoms exhibited during epileptic seizures. However, the majority of patients have a significant post-seizure silence following a serious seizure; the underlying molecular neural mechanisms in this burst interval are unclear. The aim of the present study was to reveal the effect and role of calcium-activated potassium channels during this seizure interval silence period. Cyclothiazide (CTZ) was used to establish the seizure model in rat hippocampal cultured neurons, then the after-burst hyperpolarization (ABH) activities were recorded using the patch clamp technique. By comparing the amplitude and duration of hyperpolarizations, the present study analyzed the association between epileptiform bursts and ABHs when treated with different concentrations of CTZ. In addition, apamin and iberiotoxin were used for pharmacological tests. An intracranial electroencephalogram (EEG) recording was also performed when the CTZ experiments were repeated on animals. The experimental results revealed that treatment with high levels of CTZ induced larger ABHs and was associated with stronger burst activities, which suggested a positive correlation between ABH and epileptiform burst. Apamin, an antagonist of small conductance calcium-activated potassium (SK) channels, decreased the amplitude of ABH; however, reduced ABH was associated with enhanced burst activity, in burst probability and burst strength. These results revealed an important role of SK channels in the formation of ABH and in the inhibition of burst activity. Iberiotoxin, an antagonist of big conductance calcium-activated potassium (BK) channels, had no significant effect on ABH and burst activity. In addition, a positive correlation was identified between burst duration and ABH parameters. An intracellular calcium chelator impaired the amplitude of ABH; however, it did not affect the burst parameters. The rat cortical EEG recordings also exhibited a similar positive correlation between the duration of epileptic burst and after burst depression. Collectively, the results indicate that ABH may serve in the physiological feedback system to reduce the strength of epileptic hyperexcitation, a process in which SK channels are important.
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Affiliation(s)
- Yian Huang
- Institutes of Brain Science and State Key Laboratory for Medical Neurobiology, Department of Neurology at Zhongshan Hospital, Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200032, P.R. China
| | - Xu Liu
- Institutes of Brain Science and State Key Laboratory for Medical Neurobiology, Department of Neurology at Zhongshan Hospital, Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200032, P.R. China
| | - Guoxiang Wang
- Institutes of Brain Science and State Key Laboratory for Medical Neurobiology, Department of Neurology at Zhongshan Hospital, Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200032, P.R. China
| | - Yun Wang
- Institutes of Brain Science and State Key Laboratory for Medical Neurobiology, Department of Neurology at Zhongshan Hospital, Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200032, P.R. China
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Mantegazza M, Cestèle S. Pathophysiological mechanisms of migraine and epilepsy: Similarities and differences. Neurosci Lett 2017; 667:92-102. [PMID: 29129678 DOI: 10.1016/j.neulet.2017.11.025] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Revised: 11/08/2017] [Accepted: 11/08/2017] [Indexed: 01/03/2023]
Abstract
Migraine and epilepsy are episodic disorders with distinct features, but they have some clinical and pathophysiological overlaps. We review here clinical overlaps between seizures and migraine attacks, activities of neuronal networks observed during seizures and migraine attacks, and molecular and cellular mechanisms of migraine identified in genetic forms, focusing on genetic variants identified in hemiplegic migraine and their functional effects. Epilepsy and migraine can be generated by dysfunctions of the same neuronal networks, but these dysfunctions can be disease-specific, even if pathogenic mutations target the same protein. Studies of rare monogenic forms have allowed the identification of some molecular/cellular dysfunctions that provide a window on pathological mechanisms: we have begun to disclose the tip of the iceberg.
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Affiliation(s)
- Massimo Mantegazza
- Université Côte d'Azur (UCA), 660 route des Lucioles, 06560 Valbonne, Sophia Antipolis, France; Institute of Molecular and Cellular Pharmacology (IPMC), CNRS UMR7275, 660 Route des Lucioles, 06560 Valbonne, Sophia Antipolis, France.
| | - Sandrine Cestèle
- Université Côte d'Azur (UCA), 660 route des Lucioles, 06560 Valbonne, Sophia Antipolis, France; Institute of Molecular and Cellular Pharmacology (IPMC), CNRS UMR7275, 660 Route des Lucioles, 06560 Valbonne, Sophia Antipolis, France
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22
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Milner ES, Do MTH. A Population Representation of Absolute Light Intensity in the Mammalian Retina. Cell 2017; 171:865-876.e16. [PMID: 28965762 DOI: 10.1016/j.cell.2017.09.005] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 08/02/2017] [Accepted: 09/01/2017] [Indexed: 12/12/2022]
Abstract
Environmental illumination spans many log units of intensity and is tracked for essential functions that include regulation of the circadian clock, arousal state, and hormone levels. Little is known about the neural representation of light intensity and how it covers the necessary range. This question became accessible with the discovery of mammalian photoreceptors that are required for intensity-driven functions, the M1 ipRGCs. The spike outputs of M1s are thought to uniformly track intensity over a wide range. We provide a different understanding: individual cells operate over a narrow range, but the population covers irradiances from moonlight to full daylight. The range of most M1s is limited by depolarization block, which is generally considered pathological but is produced intrinsically by these cells. The dynamics of block allow the population to code stimulus intensity with flexibility and efficiency. Moreover, although spikes are distorted by block, they are regularized during axonal propagation.
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Affiliation(s)
- Elliott Scott Milner
- F.M. Kirby Neurobiology Center and Department of Neurology, Boston Children's Hospital and Harvard Medical School, Center for Life Science 12061, Boston, MA 02115, USA; Center for Brain Science, Harvard University, Cambridge, MA 02138, USA.
| | - Michael Tri Hoang Do
- F.M. Kirby Neurobiology Center and Department of Neurology, Boston Children's Hospital and Harvard Medical School, Center for Life Science 12061, Boston, MA 02115, USA; Center for Brain Science, Harvard University, Cambridge, MA 02138, USA.
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23
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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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Peters C, Rosch RE, Hughes E, Ruben PC. Temperature-dependent changes in neuronal dynamics in a patient with an SCN1A mutation and hyperthermia induced seizures. Sci Rep 2016; 6:31879. [PMID: 27582020 PMCID: PMC5007485 DOI: 10.1038/srep31879] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 07/28/2016] [Indexed: 01/01/2023] Open
Abstract
Dravet syndrome is the prototype of SCN1A-mutation associated epilepsies. It is characterised by prolonged seizures, typically provoked by fever. We describe the evaluation of an SCN1A mutation in a child with early-onset temperature-sensitive seizures. The patient carries a heterozygous missense variant (c3818C > T; pAla1273Val) in the NaV1.1 brain sodium channel. We compared the functional effects of the variant vs. wild type NaV1.1 using patch clamp recordings from channels expressed in Chinese Hamster Ovary Cells at different temperatures (32, 37, and 40 °C). The variant channels produced a temperature-dependent destabilization of activation and fast inactivation. Implementing these empirical abnormalities in a computational model predicts a higher threshold for depolarization block in the variant, particularly at 40 °C, suggesting a failure to autoregulate at high-input states. These results reveal direct effects of abnormalities in NaV1.1 biophysical properties on neuronal dynamics. They illustrate the value of combining cellular measurements with computational models to integrate different observational scales (gene/channel to patient).
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Affiliation(s)
- C Peters
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - R E Rosch
- Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, UK.,Centre for Developmental Cognitive Neuroscience, Institute of Child Health, University College, London, UK
| | - E Hughes
- Department of Paediatric Neurology, Evelina London Children's Hospital, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - P C Ruben
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
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Wang L, Dufour S, Valiante TA, Carlen PL. Extracellular Potassium and Seizures: Excitation, Inhibition and the Role of Ih. Int J Neural Syst 2016; 26:1650044. [PMID: 27464853 DOI: 10.1142/s0129065716500441] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Seizure activity leads to increases in extracellular potassium concentration ([K[Formula: see text]]o), which can result in changes in neuronal passive and active membrane properties as well as in population activities. In this study, we examined how extracellular potassium modulates seizure activities using an acute 4-AP induced seizure model in the neocortex, both in vivo and in vitro. Moderately elevated [K[Formula: see text]]o up to 9[Formula: see text]mM prolonged seizure durations and shortened interictal intervals as well as depolarized the neuronal resting membrane potential (RMP). However, when [K[Formula: see text]]o reached higher than 9[Formula: see text]mM, seizure like events (SLEs) were blocked and neurons went into a depolarization-blocked state. Spreading depression was never observed as the blockade of ictal events could be reversed within 1-2[Formula: see text]min after the raised [K[Formula: see text]]o was changed back to control levels. This concentration-dependent dual effect of [K[Formula: see text]]o was observed using in vivo and in vitro mouse brain preparations as well as in human neocortical tissue resected during epilepsy surgery. Blocking the Ih current, mediated by hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, modulated the elevated [K[Formula: see text]]o influence on SLEs by promoting the high [K[Formula: see text]]o inhibitory actions. These results demonstrate biphasic actions of raised [K[Formula: see text]]o on neuronal excitability and seizure activity.
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Affiliation(s)
- Lihua Wang
- 1 Departments of Medicine (Neurology) and Physiology, University Health Network, University of Toronto, Toronto, M5T 2S8, Ontario, Canada
| | - Suzie Dufour
- 1 Departments of Medicine (Neurology) and Physiology, University Health Network, University of Toronto, Toronto, M5T 2S8, Ontario, Canada
| | - Taufik A Valiante
- 2 Division of Neurosurgery, Department of Surgery, University Health Network, University of Toronto, Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, M5T 2S8, Ontario, Canada
| | - Peter L Carlen
- 3 Departments of Medicine (Neurology) and Physiology, University Health Network, University of Toronto, Institute of Biomaterials and Biomedical Engineering University of Toronto, Toronto, M5T 2S8, Ontario, Canada
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26
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Castejon C, Barros-Zulaica N, Nuñez A. Control of Somatosensory Cortical Processing by Thalamic Posterior Medial Nucleus: A New Role of Thalamus in Cortical Function. PLoS One 2016; 11:e0148169. [PMID: 26820514 PMCID: PMC4731153 DOI: 10.1371/journal.pone.0148169] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 01/13/2016] [Indexed: 11/19/2022] Open
Abstract
Current knowledge of thalamocortical interaction comes mainly from studying lemniscal thalamic systems. Less is known about paralemniscal thalamic nuclei function. In the vibrissae system, the posterior medial nucleus (POm) is the corresponding paralemniscal nucleus. POm neurons project to L1 and L5A of the primary somatosensory cortex (S1) in the rat brain. It is known that L1 modifies sensory-evoked responses through control of intracortical excitability suggesting that L1 exerts an influence on whisker responses. Therefore, thalamocortical pathways targeting L1 could modulate cortical firing. Here, using a combination of electrophysiology and pharmacology in vivo, we have sought to determine how POm influences cortical processing. In our experiments, single unit recordings performed in urethane-anesthetized rats showed that POm imposes precise control on the magnitude and duration of supra- and infragranular barrel cortex whisker responses. Our findings demonstrated that L1 inputs from POm imposed a time and intensity dependent regulation on cortical sensory processing. Moreover, we found that blocking L1 GABAergic inhibition or blocking P/Q-type Ca2+ channels in L1 prevents POm adjustment of whisker responses in the barrel cortex. Additionally, we found that POm was also controlling the sensory processing in S2 and this regulation was modulated by corticofugal activity from L5 in S1. Taken together, our data demonstrate the determinant role exerted by the POm in the adjustment of somatosensory cortical processing and in the regulation of cortical processing between S1 and S2. We propose that this adjustment could be a thalamocortical gain regulation mechanism also present in the processing of information between cortical areas.
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Affiliation(s)
- Carlos Castejon
- Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
| | - Natali Barros-Zulaica
- Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
| | - Angel Nuñez
- Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
- * E-mail:
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27
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Raimondo JV, Burman RJ, Katz AA, Akerman CJ. Ion dynamics during seizures. Front Cell Neurosci 2015; 9:419. [PMID: 26539081 PMCID: PMC4612498 DOI: 10.3389/fncel.2015.00419] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Accepted: 10/04/2015] [Indexed: 12/14/2022] Open
Abstract
Changes in membrane voltage brought about by ion fluxes through voltage and transmitter-gated channels represent the basis of neural activity. As such, electrochemical gradients across the membrane determine the direction and driving force for the flow of ions and are therefore crucial in setting the properties of synaptic transmission and signal propagation. Ion concentration gradients are established by a variety of mechanisms, including specialized transporter proteins. However, transmembrane gradients can be affected by ionic fluxes through channels during periods of elevated neural activity, which in turn are predicted to influence the properties of on-going synaptic transmission. Such activity-induced changes to ion concentration gradients are a feature of both physiological and pathological neural processes. An epileptic seizure is an example of severely perturbed neural activity, which is accompanied by pronounced changes in intracellular and extracellular ion concentrations. Appreciating the factors that contribute to these ion dynamics is critical if we are to understand how a seizure event evolves and is sustained and terminated by neural tissue. Indeed, this issue is of significant clinical importance as status epilepticus—a type of seizure that does not stop of its own accord—is a life-threatening medical emergency. In this review we explore how the transmembrane concentration gradient of the six major ions (K+, Na+, Cl−, Ca2+, H+and HCO3−) is altered during an epileptic seizure. We will first examine each ion individually, before describing how multiple interacting mechanisms between ions might contribute to concentration changes and whether these act to prolong or terminate epileptic activity. In doing so, we will consider how the availability of experimental techniques has both advanced and restricted our ability to study these phenomena.
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Affiliation(s)
- Joseph V Raimondo
- Department of Human Biology, Faculty of Health Sciences, University of Cape Town Cape Town, South Africa ; UCT/MRC Receptor Biology Unit, Department of Integrative Biomedical Sciences and Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town Cape Town, South Africa
| | - Richard J Burman
- UCT/MRC Receptor Biology Unit, Department of Integrative Biomedical Sciences and Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town Cape Town, South Africa
| | - Arieh A Katz
- UCT/MRC Receptor Biology Unit, Department of Integrative Biomedical Sciences and Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town Cape Town, South Africa
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28
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Afra P, Jouny CC, Bergey GK. Termination patterns of complex partial seizures: An intracranial EEG study. Seizure 2015; 32:9-15. [PMID: 26552555 DOI: 10.1016/j.seizure.2015.08.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Revised: 07/08/2015] [Accepted: 08/12/2015] [Indexed: 01/02/2023] Open
Abstract
PURPOSE While seizure onset patterns have been the subject of many reports, there have been few studies of seizure termination. In this study we report the incidence of synchronous and asynchronous termination patterns of partial seizures recorded with intracranial arrays. METHODS Data were collected from patients with intractable complex partial seizures undergoing presurgical evaluations with intracranial electrodes. Patients with seizures originating from mesial temporal and neocortical regions were grouped into three groups based on patterns of seizure termination: synchronous only (So), asynchronous only (Ao), or mixed (S/A, with both synchronous and asynchronous termination patterns). RESULTS 88% of the patients in the MT group had seizures with a synchronous pattern of termination exclusively (38%) or mixed (50%). 82% of the NC group had seizures with synchronous pattern of termination exclusively (52%) or mixed (30%). In the NC group, there was a significant difference of the range of seizure durations between So and Ao groups, with Ao exhibiting higher variability. Seizures with synchronous termination had low variability in both groups. CONCLUSIONS Synchronous seizure termination is a common pattern for complex partials seizures of both mesial temporal or neocortical onset. This may reflect stereotyped network behavior or dynamics at the seizure focus.
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Affiliation(s)
- Pegah Afra
- Department of Neurology, School of Medicine, University of Utah, Salt Lake City, UT, United States.
| | - Christopher C Jouny
- Department of Neurology, Johns Hopkins Epilepsy Center, Johns Hopkins University School of Medicine, United States
| | - Gregory K Bergey
- Department of Neurology, Johns Hopkins Epilepsy Center, Johns Hopkins University School of Medicine, United States
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29
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Szabo GG, Schneider CJ, Soltesz I. Resolution revolution: epilepsy dynamics at the microscale. Curr Opin Neurobiol 2015; 31:239-43. [PMID: 25596364 DOI: 10.1016/j.conb.2014.12.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 12/29/2014] [Accepted: 12/30/2014] [Indexed: 11/19/2022]
Abstract
Our understanding of the neuronal mechanisms behind epilepsy dynamics has recently advanced due to the application of novel technologies, monitoring hundreds of neurons with single cell resolution. These developments have provided new theories on the relationship between physiological and pathological states, as well as common motifs for the propagation of paroxysmal activity. Although traditional electroencephalogram (EEG) recordings continue to describe normal network oscillations and abnormal epileptic events within and outside of the seizure focus, analysis of epilepsy dynamics at the microscale has found variability in the composition of macroscopically repetitive epileptiform events. These novel results point to heterogeneity in the underlying dynamics of the disorder, highlighting both the need and potential for more specific and targeted therapies.
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Affiliation(s)
- Gergely G Szabo
- Department of Anatomy and Neurobiology, University of California, Irvine, CA 92697, USA
| | - Calvin J Schneider
- Department of Anatomy and Neurobiology, University of California, Irvine, CA 92697, USA
| | - Ivan Soltesz
- Department of Anatomy and Neurobiology, University of California, Irvine, CA 92697, USA.
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30
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O'Carroll SJ, Becker DL, Davidson JO, Gunn AJ, Nicholson LFB, Green CR. The use of connexin-based therapeutic approaches to target inflammatory diseases. Methods Mol Biol 2014; 1037:519-46. [PMID: 24029957 DOI: 10.1007/978-1-62703-505-7_31] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Alterations in Connexin43 (Cx43) expression levels have been shown to play a role in inflammatory processes including skin wounding and neuroinflammation. Cx43 protein levels increase following a skin wound and can inhibit wound healing. Increased Cx43 has been observed following stroke, epilepsy, ischemia, optic nerve damage, and spinal cord injury with gap junctional communication and hemichannel opening leading to increased secondary damage via the inflammatory response. Connexin43 modulation has been identified as a potential target for protection and repair in neuroinflammation and skin wound repair. This review describes the use of a Cx43 specific antisense oligonucleotide (Cx43 AsODN) and peptide mimetics of the connexin extracellular loop domain to modulate Cx43 expression and/or function in inflammatory disorders of the skin and central nervous system. An overview of the role of connexin43 in inflammatory conditions, how antisense and peptide have allowed us to elucidate the role of Cx43 in these diseases, create models of diseases to test interventions and their potential for use clinically or in current clinical trials is presented. Antisense oligonucleotides are applied topically and have been used to improve wound healing following skin injury. They have also been used to develop ex vivo models of neuroinflammatory diseases that will allow testing of intervention strategies. The connexin mimetic peptides have shown potential in a number of neuroinflammatory disorders in ex vivo models as well as in vivo when delivered directly to the injury site or when delivered systemically.
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Affiliation(s)
- Simon J O'Carroll
- Department of Anatomy with Radiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
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31
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Boido D, Gnatkovsky V, Uva L, Francione S, de Curtis M. Simultaneous enhancement of excitation and postburst inhibition at the end of focal seizures. Ann Neurol 2014; 76:826-36. [PMID: 24916758 DOI: 10.1002/ana.24193] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 06/04/2014] [Accepted: 06/04/2014] [Indexed: 11/10/2022]
Abstract
OBJECTIVE Comprehension of the events that lead to seizure termination contributes to the development of strategies to confine propagation of ictal discharges. It is commonly assumed that the inhibitory control fails during seizures and recovers after the end of the ictal event. We examine the possibility that a progressive increase of inhibition that counters an increase in the strength of excitation contributes to terminating a focal seizure. METHODS We analyzed seizures acutely induced by pharmacological manipulations (bicuculline and 4-aminopyridine) in the entorhinal cortex and in the hippocampus of the in vitro isolated guinea pig brain. RESULTS As seizures ended, extracellular and intracellular recordings showed periodic bursting that progressively decreased in frequency. During the late bursting phase, the duration, number, and rate of occurrence of spikes within single bursts remained constant, whereas cumulative spike amplitude (index of excitation during a burst) and interburst interval (index of inhibition between bursts) progressively increased. The increment of average/cumulative burst excitation and interburst interval toward seizure end was confirmed in human focal seizures recorded with intracerebral electrodes in patients with drug-resistant partial epilepsies. A postburst refractory period of circa 2 seconds that increases with time toward the end of the seizure was confirmed in the experimental model by probing interburst epochs in the CA1 region with local dentate gyrus stimulation just suprathreshold for burst generation. INTERPRETATION Our findings support the concept that focal seizures are terminated by the simultaneous and opposing enhancement of excitation (burst activity) in addition to postburst inhibition. We hypothesize that a seizure stops when postburst inhibition becomes large enough to prevent reactivation of excitation.
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Affiliation(s)
- Davide Boido
- Unit of Epileptology and Experimental Neurophysiology, Carlo Besta Neurological Institute Foundation, Milan, Italy
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32
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Zandt BJ, Stigen T, Ten Haken B, Netoff T, van Putten MJAM. Single neuron dynamics during experimentally induced anoxic depolarization. J Neurophysiol 2013; 110:1469-75. [PMID: 23825394 DOI: 10.1152/jn.00250.2013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We studied single neuron dynamics during anoxic depolarizations, which are often observed in cases of neuronal energy depletion. Anoxic and similar depolarizations play an important role in several pathologies, notably stroke, migraine, and epilepsy. One of the effects of energy depletion was experimentally simulated in slices of rat cortex by blocking the sodium-potassium pumps with ouabain. The membrane voltage of pyramidal cells was measured. Five different kinds of dynamical behavior of the membrane voltage were observed during the resulting depolarizations. Using bifurcation analysis of a single cell model, we show that these voltage dynamics all are responses of the same cell, with normally functioning ion channels, to particular courses of the intra- and extracellular concentrations of sodium and potassium.
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Affiliation(s)
- Bas-Jan Zandt
- MIRA-Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
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33
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Feng Z, Zheng X, Yu Y, Durand DM. Functional disconnection of axonal fibers generated by high frequency stimulation in the hippocampal CA1 region in-vivo. Brain Res 2013; 1509:32-42. [PMID: 23473842 PMCID: PMC3631450 DOI: 10.1016/j.brainres.2013.02.048] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Revised: 02/20/2013] [Accepted: 02/26/2013] [Indexed: 11/18/2022]
Abstract
High frequency stimulation (HFS) applied in the brain has been shown to be efficient for treating several brain disorders, such as Parkinson's disease and epilepsy. But the mechanisms underlying HFS are not clear. In particular, the effect of HFS on axons has been intriguing since axonal propagation plays an important role in the functional outcome of HFS. In order to study the potential effect of axonal block by HFS in-vivo, both orthodromic- and antidromic-HFS (O-HFS, A-HFS) with biphasic pulses were applied to the hippocampal CA1 region in anaesthetized rats. Changes in the amplitude and latency of orthodromic- and antidromic-population spikes within 1-min long period of stimulation at 50, 100 and 200 Hz HFS were analyzed. The results show that except for a short onset period, activity evoked by O-HFS with a frequency over 100 Hz could not be sustained. For A-HFS at frequencies over 100 Hz, the amplitudes and the latencies of antidromic population spike (APS) greatly decreased and increased respectively. Significantly larger changes in APS latency were observed in HFS than those generated at low frequency, suggesting a suppression of axon conduction by HFS. Furthermore, the CA1 somata remained excitable while failing to respond to excitation from orthodromic or antidromic HFS. Taken together, these results show that HFS produces an axonal block of both afferent and efferent fibers localized to the area of stimulation since it does not affect the excitability of CA1 somata. This effect of HFS on axons causes a functional disconnection of axonal pathways that is reversible and temporary. The reversible disconnection or temporary deafferentation between putative therapeutic targets could have extensive implication for various clinical applications of HFS to treat brain diseases.
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Affiliation(s)
- Zhouyan Feng
- Ministry of Education Key Lab of Biomedical Engineering, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, Zhejiang 310027, PR China.
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34
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Synchronization Implies Seizure or Seizure Implies Synchronization? Brain Topogr 2013; 27:112-22. [DOI: 10.1007/s10548-013-0284-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Accepted: 03/26/2013] [Indexed: 10/27/2022]
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Prenatal stress exposure increases the excitation of dopamine neurons in the ventral tegmental area and alters their reponses to psychostimulants. Neuropsychopharmacology 2013; 38:293-301. [PMID: 22948974 PMCID: PMC3527115 DOI: 10.1038/npp.2012.168] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Prenatal stress exposure (PSE) is known to increase addiction risk. Dopamine (DA) neurons in the ventral tegmental area (VTA) play an important role in addiction. In order to understand the cellular mechanisms underlying PSE-induced increase in addiction risk, we examined the effects of PSE on the electrical impulse activity of VTA DA neurons using the in vivo extracellular single-unit recording technique. Amphetamine self-administration was also conducted to confirm increased addiction risk after PSE. The PSE was carried out by restraining pregnant dams from GD 11 to 20. Adult male offspring (3-6 months old) were used in the experiments. Animals with PSE showed enhanced amphetamine self-administration compared with controls when amphetamine dose was reduced after acquisition. The number of spontaneously active VTA DA neurons was also reduced in PSE rats. The reduction was reversed by acute apomorphine that normally inhibits the impulse activity of DA neurons. The reversal effect suggests that PSE-induced reduction in the number of spontaneously active VTA DA neurons is caused by overexcitation to the extent of depolarization block. Furthermore, the reduced number of spontaneously active VTA DA neurons was also reversed by acute psychostimulants (eg, amphetamine; cocaine), which in control rats inhibited the activity of VTA DA neurons. The reversal effect on VTA DA neuron in PSE animals represents an actual increase in the impulse activity. This effect might contribute to increased responding to psychostimulants and mediate increased addiction risk after PSE.
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36
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Human seizures self-terminate across spatial scales via a critical transition. Proc Natl Acad Sci U S A 2012; 109:21116-21. [PMID: 23213262 DOI: 10.1073/pnas.1210047110] [Citation(s) in RCA: 133] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Why seizures spontaneously terminate remains an unanswered fundamental question of epileptology. Here we present evidence that seizures self-terminate via a discontinuous critical transition or bifurcation. We show that human brain electrical activity at various spatial scales exhibits common dynamical signatures of an impending critical transition--slowing, increased correlation, and flickering--in the approach to seizure termination. In contrast, prolonged seizures (status epilepticus) repeatedly approach, but do not cross, the critical transition. To support these results, we implement a computational model that demonstrates that alternative stable attractors, representing the ictal and postictal states, emulate the observed dynamics. These results suggest that self-terminating seizures end through a common dynamical mechanism. This description constrains the specific biophysical mechanisms underlying seizure termination, suggests a dynamical understanding of status epilepticus, and demonstrates an accessible system for studying critical transitions in nature.
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38
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Albus K, Wahab A, Heinemann U. Primary afterdischarge in organotypic hippocampal slice cultures: Effects of standard antiepileptic drugs. Epilepsia 2012; 53:1928-36. [DOI: 10.1111/j.1528-1167.2012.03597.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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39
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Carlen PL. Curious and contradictory roles of glial connexins and pannexins in epilepsy. Brain Res 2012; 1487:54-60. [PMID: 22796594 DOI: 10.1016/j.brainres.2012.06.059] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Revised: 06/19/2012] [Accepted: 06/20/2012] [Indexed: 10/28/2022]
Abstract
Glia play an under-recognized role in epilepsy. This review examines the involvement of glial connexins (Cxs) and pannexins (Panxs), proteins which form gap junctions and membrane hemichannels (connexins) and hemichannels (pannexins), in epilepsy. These proteins, particularly glial Cx43, have been shown to be upregulated in epileptic brain tissue. In a cobalt model of in vitro seizures, seizures increased Panxs1 and 2 and Cx43 expression, and remarkably reorganized the interrelationships between their mRNA levels (transcriptome) which then became statistically significant. Gap junctions are highly implicated in synchronous seizure activity. Blocking gap junctional communication (GJC) is often anticonvulsant, and assumed to be due to blocking gap junctionally-medicated electrotonic coupling between neurons. However, in organotypic hippocampal slice cultures, connexin43 specific peptides, which attenuate GJC possibly by blocking connexon docking, diminished spontaneous seizures. Glia have many functions including extracellular potassium redistribution, in part via gap junctions, which if blocked, can be seizuregenic. Glial gap junctions are critical for the delivery of nutrients to neurons, which if interrupted, can depress seizure activity. Other functions of glia possibly related to epileptogenesis are mentioned including anatomic reorganization in chronic seizure models greatly increasing the overlapping domains of glial processes, changes in neurotransmitter re-uptake, and possible glial generation of currents and fields during seizure activity. Finally there is recent evidence for Cx43 hemichannels and Panx1 channels in glial membranes which could play a role in brain damage and seizure activity. Although glial Cxs and Panxs are increasingly recognized as contributing to fundamental mechanisms of epilepsy, the data are often contradictory and controversial, requiring much more research. This article is part of a Special Issue entitled Electrical Synapses.
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Affiliation(s)
- Peter L Carlen
- Toronto Western Research Institute, Epilepsy Program, University Health Network, Toronto, Ontario, Canada M5T2S8.
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Dreier JP, Major S, Pannek HW, Woitzik J, Scheel M, Wiesenthal D, Martus P, Winkler MKL, Hartings JA, Fabricius M, Speckmann EJ, Gorji A. Spreading convulsions, spreading depolarization and epileptogenesis in human cerebral cortex. Brain 2011; 135:259-75. [PMID: 22120143 PMCID: PMC3267981 DOI: 10.1093/brain/awr303] [Citation(s) in RCA: 185] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Spreading depolarization of cells in cerebral grey matter is characterized by massive ion translocation, neuronal swelling and large changes in direct current-coupled voltage recording. The near-complete sustained depolarization above the inactivation threshold for action potential generating channels initiates spreading depression of brain activity. In contrast, epileptic seizures show modest ion translocation and sustained depolarization below the inactivation threshold for action potential generating channels. Such modest sustained depolarization allows synchronous, highly frequent neuronal firing; ictal epileptic field potentials being its electrocorticographic and epileptic seizure its clinical correlate. Nevertheless, Leão in 1944 and Van Harreveld and Stamm in 1953 described in animals that silencing of brain activity induced by spreading depolarization changed during minimal electrical stimulations. Eventually, epileptic field potentials were recorded during the period that had originally seen spreading depression of activity. Such spreading convulsions are characterized by epileptic field potentials on the final shoulder of the large slow potential change of spreading depolarization. We here report on such spreading convulsions in monopolar subdural recordings in 2 of 25 consecutive aneurismal subarachnoid haemorrhage patients in vivo and neocortical slices from 12 patients with intractable temporal lobe epilepsy in vitro. The in vitro results suggest that γ-aminobutyric acid-mediated inhibition protects from spreading convulsions. Moreover, we describe arterial pulse artefacts mimicking epileptic field potentials in three patients with subarachnoid haemorrhage that ride on the slow potential peak. Twenty-one of the 25 subarachnoid haemorrhage patients (84%) had 656 spreading depolarizations in contrast to only three patients (12%) with 55 ictal epileptic events isolated from spreading depolarizations. Spreading depolarization frequency and depression periods per 24 h recording episodes showed an early and a delayed peak on Day 7. Patients surviving subarachnoid haemorrhage with poor outcome at 6 months showed significantly higher total and peak numbers of spreading depolarizations and significantly longer total and peak depression periods during the electrocorticographic monitoring than patients with good outcome. In a semi-structured telephone interview 3 years after the initial haemorrhage, 44% of the subarachnoid haemorrhage survivors had developed late post-haemorrhagic seizures requiring anti-convulsant medication. In those patients, peak spreading depolarization number had been significantly higher [15.1 (11.4–30.8) versus 7.0 (0.8–11.2) events per day, P = 0.045]. In summary, monopolar recordings here provided unequivocal evidence of spreading convulsions in patients. Hence, practically all major pathological cortical network events in animals have now been observed in people. Early spreading depolarizations may indicate a risk for late post-haemorrhagic seizures.
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Affiliation(s)
- Jens P Dreier
- Centre for Stroke Research Berlin, Charité University Medicine Berlin, 10117 Berlin, Germany.
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Zhang ZJ, Valiante TA, Carlen PL. Transition to seizure: from "macro"- to "micro"-mysteries. Epilepsy Res 2011; 97:290-9. [PMID: 22075227 DOI: 10.1016/j.eplepsyres.2011.09.025] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 09/25/2011] [Accepted: 09/27/2011] [Indexed: 01/25/2023]
Abstract
One of the most terrifying aspects of epilepsy is the sudden and apparently unpredictable transition of the brain into the pathological state of an epileptic seizure. The pathophysiology of the transition to seizure still remains mysterious. Herein we review some of the key concepts and relevant literatures dealing with this enigmatic transitioning of brain states. At the "MACRO" level, electroencephalographic (EEG) recordings at time display preictal phenomena followed by pathological high-frequency oscillations at the seizure onset. Numerous seizure prediction algorithms predicated on identifying changes prior to seizure onset have met with little success, underscoring our lack of understanding of the dynamics of transition to seizure, amongst other inherent limitation. We then discuss the concept of synchronized hyperexcited oscillatory networks underlying seizure generation. We consider these networks as weakly coupled oscillators, a concept which forms the basis of some relevant mathematical modeling of seizure transitions. Next, the underlying "MICRO" processes involved in seizure generation are discussed. The depolarization of the GABA(A) chloride reversal potential is a major concept, facilitating epileptogenesis, particularly in immature brain. Also the balance of inhibitory and excitatory local neuronal networks plays an important role in the process of transitioning to seizure. Gap junctional communication, including that which occurs between glia, as well as ephaptic interactions are increasingly recognized as critical for seizure generation. In brief, this review examines the evidence regarding the characterization of the transition to seizure at both the "MACRO" and "MICRO" levels, trying to characterize this mysterious yet critical problem of the brain state transitioning into a seizure.
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Affiliation(s)
- Z J Zhang
- Division of Fundamental Neurobiology, Toronto Western Research Institute, Toronto Western Hospital, Toronto, ON, Canada.
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42
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Igelström KM, Shirley CH, Heyward PM. Low-magnesium medium induces epileptiform activity in mouse olfactory bulb slices. J Neurophysiol 2011; 106:2593-605. [PMID: 21832029 DOI: 10.1152/jn.00601.2011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Magnesium-free medium can be used in brain slice studies to enhance glutamate receptor function, but this manipulation causes seizure-like activity in many cortical areas. The rodent olfactory bulb (OB) slice is a popular preparation, and potentially ictogenic ionic conditions have often been used to study odor processing. We studied low Mg(2+)-induced epileptiform discharges in mouse OB slices using extracellular and whole cell electrophysiological recordings. Low-Mg(2+) medium induced two distinct types of epileptiform activity: an intraglomerular delta-frequency oscillation resembling slow sniff-induced activity and minute-long seizure-like events (SLEs) consisting of large negative-going field potentials accompanied by sustained depolarization of output neurons. SLEs were dependent on N-methyl-D-aspartate receptors and sodium currents and were facilitated by α-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptors. The events were initiated in the glomerular layer and propagated laterally through the external plexiform layer at a slow time scale. Our findings confirm that low-Mg(2+) medium should be used with caution in OB slices. Furthermore, the SLEs resembled the so-called slow direct current (DC) shift of clinical and experimental seizures, which has recently been recognized as being of great clinical importance. The OB slice may therefore provide a robust and unique in vitro model of acute seizures in which mechanisms of epileptiform DC shifts can be studied in isolation from fast oscillations.
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Affiliation(s)
- Kajsa M Igelström
- Dept. of Physiology, Univ. of Otago, PO Box 913, Dunedin 9054, New Zealand.
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Truccolo W, Donoghue JA, Hochberg LR, Eskandar EN, Madsen JR, Anderson WS, Brown EN, Halgren E, Cash SS. Single-neuron dynamics in human focal epilepsy. Nat Neurosci 2011; 14:635-41. [PMID: 21441925 DOI: 10.1038/nn.2782] [Citation(s) in RCA: 341] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Accepted: 02/15/2011] [Indexed: 11/09/2022]
Abstract
Epileptic seizures are traditionally characterized as the ultimate expression of monolithic, hypersynchronous neuronal activity arising from unbalanced runaway excitation. Here we report the first examination of spike train patterns in large ensembles of single neurons during seizures in persons with epilepsy. Contrary to the traditional view, neuronal spiking activity during seizure initiation and spread was highly heterogeneous, not hypersynchronous, suggesting complex interactions among different neuronal groups even at the spatial scale of small cortical patches. In contrast to earlier stages, seizure termination is a nearly homogenous phenomenon followed by an almost complete cessation of spiking across recorded neuronal ensembles. Notably, even neurons outside the region of seizure onset showed significant changes in activity minutes before the seizure. These findings suggest a revision of current thinking about seizure mechanisms and point to the possibility of seizure prevention based on spiking activity in neocortical neurons.
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Affiliation(s)
- Wilson Truccolo
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA.
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45
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Yoon JJ, Green CR, O’Carroll SJ, Nicholson LF. Dose-dependent protective effect of connexin43 mimetic peptide against neurodegeneration in an ex vivo model of epileptiform lesion. Epilepsy Res 2010; 92:153-62. [DOI: 10.1016/j.eplepsyres.2010.08.014] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Revised: 08/23/2010] [Accepted: 08/24/2010] [Indexed: 11/30/2022]
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Tufail Y, Matyushov A, Baldwin N, Tauchmann ML, Georges J, Yoshihiro A, Tillery SIH, Tyler WJ. Transcranial pulsed ultrasound stimulates intact brain circuits. Neuron 2010; 66:681-94. [PMID: 20547127 DOI: 10.1016/j.neuron.2010.05.008] [Citation(s) in RCA: 573] [Impact Index Per Article: 40.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/29/2010] [Indexed: 12/13/2022]
Abstract
Electromagnetic-based methods of stimulating brain activity require invasive procedures or have other limitations. Deep-brain stimulation requires surgically implanted electrodes. Transcranial magnetic stimulation does not require surgery, but suffers from low spatial resolution. Optogenetic-based approaches have unrivaled spatial precision, but require genetic manipulation. In search of a potential solution to these limitations, we began investigating the influence of transcranial pulsed ultrasound on neuronal activity in the intact mouse brain. In motor cortex, ultrasound-stimulated neuronal activity was sufficient to evoke motor behaviors. Deeper in subcortical circuits, we used targeted transcranial ultrasound to stimulate neuronal activity and synchronous oscillations in the intact hippocampus. We found that ultrasound triggers TTX-sensitive neuronal activity in the absence of a rise in brain temperature (<0.01 degrees C). Here, we also report that transcranial pulsed ultrasound for intact brain circuit stimulation has a lateral spatial resolution of approximately 2 mm and does not require exogenous factors or surgical invasion.
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Affiliation(s)
- Yusuf Tufail
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA
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Easter A, Bell ME, Damewood JR, Redfern WS, Valentin JP, Winter MJ, Fonck C, Bialecki RA. Approaches to seizure risk assessment in preclinical drug discovery. Drug Discov Today 2009; 14:876-84. [PMID: 19545644 DOI: 10.1016/j.drudis.2009.06.003] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Revised: 06/09/2009] [Accepted: 06/10/2009] [Indexed: 01/01/2023]
Abstract
Assessment of seizure risk traditionally occurs late in the drug discovery process using low-throughput, resource intensive in vivo assays. Such approaches do not allow sufficient time to mitigate risk by influencing chemical design. Early identification using cheaper, higher throughput assays with lower animal and compound requirements would be preferable. Here we review the current techniques available to assess this issue and describe how they may be combined in a rational step-wise cascade allowing more effective assessment of seizure risk.
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Affiliation(s)
- Alison Easter
- Safety Assessment US, AstraZeneca R&D Wilmington, DE 19850, USA.
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48
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Xiao Z, Deng PY, Yang C, Lei S. Modulation of GABAergic transmission by muscarinic receptors in the entorhinal cortex of juvenile rats. J Neurophysiol 2009; 102:659-69. [PMID: 19494196 DOI: 10.1152/jn.00226.2009] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Whereas the entorhinal cortex (EC) receives profuse cholinergic innervations from the basal forebrain and activation of cholinergic receptors has been shown to modulate the activities of the principal neurons and promote the intrinsic oscillations in the EC, the effects of cholinergic receptor activation on GABAergic transmission in this brain region have not been determined. We examined the effects of muscarinic receptor activation on GABA(A) receptor-mediated synaptic transmission in the superficial layers of the EC. Application of muscarine dose-dependently increased the frequency and amplitude of spontaneous inhibitory postsynaptic currents (IPSCs) recorded from the principal neurons in layer II/III via activation of M(3) muscarinic receptors. Muscarine slightly reduced the frequency but had no effects on the amplitude of miniature IPSCs recorded in the presence of tetrodotoxin. Muscarine reduced the amplitude of IPSCs evoked by extracellular field stimulation and by depolarization of GABAergic interneurons in synaptically connected interneuron and pyramidal neuron pairs. Application of muscarine generated membrane depolarization and increased action potential firing frequency but reduced the amplitude of action potentials in GABAergic interneurons. Muscarine-induced depolarization of GABAergic interneurons was mediated by inhibition of background K(+) channels and independent of phospholipase C, intracellular Ca(2+) release, and protein kinase C. Our results demonstrate that activation of muscarinic receptors exerts diverse effects on GABAergic transmission in the EC.
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Affiliation(s)
- Zhaoyang Xiao
- Department of Pharmacology, Physiology and Therapeutics, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota 58203, USA
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Musto AE, Samii MS, Hayes JF. Different phases of afterdischarge during rapid kindling procedure in mice. Epilepsy Res 2009; 85:199-205. [PMID: 19375287 DOI: 10.1016/j.eplepsyres.2009.02.020] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2009] [Revised: 02/17/2009] [Accepted: 02/27/2009] [Indexed: 11/24/2022]
Abstract
The basic mechanisms of hippocampal networks in epileptogenesis are not entirely understood. To help achieve a better understanding of these mechanisms, we studied the extra-cellular electrically evoked responses in the hippocampi of mice during rapid kindling. Kindling protocol was achieved by stimulating the dorsal right hippocampus six times daily for four days using bipolar electrodes to produce sub-convulsive electrical discharges. Motor responses and analyzed electroencephalographic recordings showed progression from partial complex seizures to generalized seizures associated with different consecutive patterns within the afterdischarges. A spike-wave pattern appeared immediately after stimulation in combination with a poly-spike complex superimposed over the wave (AD1). AD1 was followed by a poly-spike complex (AD2), which was followed by a progressive modification of repetitive spikes (AD3). An ictal depression event was observed at the end of each AD3. Theta oscillations were observed at stage 1-2 of kindling, while beta/gamma oscillations appeared within AD2, associated with stage 4-5 from Racine's score. Benzodiazepine, a GABA (A) agonist (Diazepam) administered at non-sedative doses and only on days 3 and 4 of kindling, limited beta and gamma frequency bands and the progression of seizure severity, suggesting that the failure of GABA (A) agonism mediates the propagation or generalization of seizures. We conclude that different phases of afterdischarge occur during kindling and that high frequencies mediate generalization of seizures.
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Affiliation(s)
- Alberto E Musto
- Department of Neurosurgery, Louisiana State University Health Sciences Center, 2020 Gravier Street, Suite D, New Orleans, LA 70112, USA.
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Ziemann AE, Schnizler MK, Albert GW, Severson MA, Howard MA, Welsh MJ, Wemmie JA. Seizure termination by acidosis depends on ASIC1a. Nat Neurosci 2008; 11:816-22. [PMID: 18536711 PMCID: PMC2553357 DOI: 10.1038/nn.2132] [Citation(s) in RCA: 271] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2008] [Accepted: 05/02/2008] [Indexed: 12/12/2022]
Abstract
Most seizures stop spontaneously; however, the molecular mechanisms that terminate seizures remain unknown. Observations that seizures reduced brain pH and that acidosis inhibited seizures indicate that acidosis halts epileptic activity. Because acid-sensing ion channel 1a (ASIC1a) is exquisitely sensitive to extracellular pH and regulates neuron excitability, we hypothesized that acidosis might activate ASIC1a, which would terminate seizures. Disrupting mouse ASIC1a increased the severity of chemoconvulsant-induced seizures, whereas overexpressing ASIC1a had the opposite effect. ASIC1a did not affect seizure threshold or onset, but shortened seizure duration and prevented seizure progression. CO2 inhalation, long known to lower brain pH and inhibit seizures, required ASIC1a to interrupt tonic-clonic seizures. Acidosis activated inhibitory interneurons through ASIC1a, suggesting that ASIC1a might limit seizures by increasing inhibitory tone. Our results identify ASIC1a as an important element in seizure termination when brain pH falls and suggest both a molecular mechanism for how the brain stops seizures and new therapeutic strategies.
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Affiliation(s)
- Adam E Ziemann
- Medical Scientist Training Program, University of Iowa, Iowa City, Iowa 52242, USA
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