Epileptic fast intracerebral EEG activity: evidence for spatial decorrelation at seizure onset.Report as inadecuate

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* Corresponding author 1 LTSI - Laboratoire Traitement du Signal et de l-Image 2 Epilepsies, Lesions Cerebrales et Systemes Neuraux de la Cognition

Abstract : Low-voltage rapid discharges or fast EEG ictal activity constitute a characteristic electrophysiological pattern in focal seizures of human epilepsy. They are characterized by a decrease of signal voltage with a marked increase of signal frequency typically beyond 25 Hz. They have long been observed in stereoelectroencephalographic SEEG signals recorded with intra-cerebral electrodes, generally occurring at seizure onset and simultaneously involving distinct brain regions. Spectral properties of rapid ictal discharges as well as spatial correlations measured between SEEG signals generated from distant sites before, during and after these discharges were studied. Cross-correlation estimates within typical EEG sub-bands and statistical tests performed in 10 patients suffering from partial epilepsy frontal, temporal or fronto-temporal reveal that SEEG signals are significantly de-correlated during the discharge period compared with periods that precede and follow this discharge. These results can be interpreted as a functional decoupling of distant brain sites at seizure onset followed by an abnormally high re-coupling when the seizure develops. They lead to the concept of -disruption- that is complementary of that of -activation- revealed by significantly high correlations between signals recorded during seizures, both giving insights into our understanding of pathophysiological processes involved in human partial epilepsies as well as in the interpretation of clinical semiology.

Keywords : Statistical tests intracerebral EEG SEEG Statistical Coupling Synchronization Correlation Spectral analysis seizure onset very fast oscillations

Author: Fabrice Wendling - Fabrice Bartolomei - Jean-Jacques Bellanger - Jérôme Bourien - Patrick Chauvel -

Source: https://hal.archives-ouvertes.fr/


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