Single-unit activities during the transition to seizures in deep mesial structures

ABSTRACT

Focal seizures are assumed to arise from a hypersynchronous activity affecting a circumscribed brain region. Using microelectrodes in seizure-generating deep mesial regions of 9 patients, we investigated the firing of hundreds of single-neurons before, during and after ictal EEG discharges. Neuronal spiking activity at seizure initiation was highly heterogeneous and not hypersynchronous. Furthermore, groups of neurons showed significant changes in activity minutes before the seizure with no concomitant changes in the corresponding macroscopic EEG recordings. Altogether, our findings suggest that only limitedsubsets of neurons in epileptic depth regions initiate the seizure-onset and that ictogenic mechanisms operate in sub-millimeter-scale microdomains. This article is protected by copyright. All rights reserved.

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