• Open Access

Synchronization and desynchronization in epilepsy: controversies and hypotheses

Authors

  • Premysl Jiruska,

    1. Department of Developmental Epileptology, Institute of Physiology, Academy of Sciences of Czech Republic, Prague, CZ-14220, Czech Republic
    2. Department of Neurology, Charles University, 2nd School of Medicine, University Hospital Motol Prague, CZ-15006, Czech Republic
    3. Neuronal Networks Group, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham B15 2TT, UK
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  • Marco de Curtis,

    1. Unit of Experimental Neurophysiology and Epileptology, Fondazione Istituto Neurologico Carlo Besta, Milan, Italy
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  • John G. R. Jefferys,

    1. Neuronal Networks Group, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham B15 2TT, UK
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  • Catherine A. Schevon,

    1. Department of Neurology, Columbia University, New York, NY, USA
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  • Steven J. Schiff,

    1. Center for Neural Engineering, Departments of Engineering Science and Mechanics, Neurosurgery, and Physics, The Pennsylvania State University, University Park, PA 16802 USA
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  • Kaspar Schindler

    1. Department of Neurology, Bern University Hospital, Bern, Switzerland
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  • The report was presented at the symposium Why do some brains seize? Molecular, cellular and network mechanisms, which took place at the Epilepsy Research UK Expert International Workshop, Oxford, UK on 15–16 March 2012.

P. Jiruska: Department of Developmental Epileptology, Institute of Physiology, Academy of Sciences of Czech Republic, Videnska 1083, Prague 4-Krc, Czech Republic, CZ-14220. Email: jiruskapremysl@gmail.com

Abstract

Abstract  Epilepsy has been historically seen as a functional brain disorder associated with excessive synchronization of large neuronal populations leading to a hypersynchronous state. Recent evidence showed that epileptiform phenomena, particularly seizures, result from complex interactions between neuronal networks characterized by heterogeneity of neuronal firing and dynamical evolution of synchronization. Desynchronization is often observed preceding seizures or during their early stages; in contrast, high levels of synchronization observed towards the end of seizures may facilitate termination. In this review we discuss cellular and network mechanisms responsible for such complex changes in synchronization. Recent work has identified cell-type-specific inhibitory and excitatory interactions, the dichotomy between neuronal firing and the non-local measurement of local field potentials distant to that firing, and the reflection of the neuronal dark matter problem in non-firing neurons active in seizures. These recent advances have challenged long-established views and are leading to a more rigorous and realistic understanding of the pathophysiology of epilepsy.

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