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High-Frequency network activity, global increase in Neuronal Activity, and Synchrony Expansion Precede Epileptic Seizures In Vitro

Jiruska, P. and Csicsvari, J. and Powell, A. D. and Fox, J. E. and Chang, W. C. and Vreugdenhil, Martin and Li, X. and Palus, M. and Bujan, A. F. and Dearden, R. W. and Jefferys, J. G. R. (2010) High-Frequency network activity, global increase in Neuronal Activity, and Synchrony Expansion Precede Epileptic Seizures In Vitro. Journal of Neuroscience, 30 (16). p. 5690. ISSN 0270-6474

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URL of Published Version: http://dx.doi.org/10.1523/JNEUROSCI.0535-10.2010

Identification Number/DOI: doi:10.1523/JNEUROSCI.0535-10.2010

How seizures start is a major question in epilepsy research. Preictal EEG changes occur in both human patients and animal models, but their underlying mechanisms and relationship with seizure initiation remain unknown. Here we demonstrate the existence, in the hippocampal CA1 region, of a preictal state characterized by the progressive and global increase in neuronal activity associated with a widespread buildup of low-amplitude high-frequency activity (HFA) (100 Hz) and reduction in system complexity.HFAis generated by the firing of neurons, mainly pyramidal cells, at much lower frequencies. Individual cycles ofHFAare generated by the near-synchronous (within 5 ms) firing of small numbers of pyramidal cells. The presence of HFA in the low-calcium model implicates nonsynaptic synchronization; the presence of very similar HFA in the high-potassium model shows that it does not depend on an absence of synaptic transmission. Immediately before seizure onset, CA1 is in a state of high sensitivity in which weak depolarizing or synchronizing perturbations can trigger seizures. Transition to seizure is haracterized by a rapid expansion and fusion of the neuronal populations responsible for HFA, associated with a progressive slowing of HFA, leading to a single, massive, hypersynchronous cluster generating the high-amplitude low-frequency activity of the seizure.

Type of Work:Article
Date:2010 (Publication)
School/Faculty:Colleges (2008 onwards) > College of Engineering & Physical Sciences
Department:School of Computer Sciences
Subjects:R Medicine (General)
Institution:University of Birmingham
Copyright Holders:Society for Neuroscience
ID Code:419
Refereed:YES
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