Abstract
Understanding changes in brain rhythms provides useful information to predict the onset of a seizure and to localize its onset zone in epileptic patients. Brain rhythms dynamics in general, and phase-amplitude coupling in particular, are known to be drastically altered during epileptic seizures. However, the neural processes that take place before a seizure are not well understood. We analysed the phase-amplitude coupling dynamics of stereoelectroencephalography recordings (30 seizures, 5 patients) before and after seizure onset. Electrodes near the seizure onset zone showed higher phase-amplitude coupling. Immediately before the beginning of the seizure, phase-amplitude coupling dropped to values similar to the observed in electrodes far from the seizure onset zone. Thus, our results bring accurate information to detect epileptic events during pre-ictal periods and to delimit the zone of seizure onset in patients undergoing epilepsy surgery.
Highlights
Understanding changes in brain rhythms provides useful information to predict the onset of a seizure and to localize its onset zone in epileptic patients
We focused our analysis on the coupling dynamic between the phase of low frequencies and the amplitude of high frequencies
In this work we asked whether a specific kind of synchronization could aid in the characterization of seizure onset
Summary
Understanding changes in brain rhythms provides useful information to predict the onset of a seizure and to localize its onset zone in epileptic patients. The “frequency spectrum as well as the interareal synchronization at seizure onset constitute a pattern of organization that is reproducible from one seizure to another”[6], and its localization is critical for successful surgical treatment In this regard, measuring PAC has been useful for SoZ localization[7]. While phase locking between low frequencies (2–25 Hz) and high gamma (80–150 Hz) increased after seizure onset[2], slow wave driven modulation of high gamma was identified during preictal periods in some epileptic patients[11]. Studying the activity that precedes ictal onset is appealing because it may reveal the mechanisms that trigger the seizure In this regard, the goal of the present work was to study the dynamics of PAC phenomena before and gmail.com www.nature.com/scientificreports/
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