INTERHEMISPHERIC EEG COHERENCE AFTER CORPUS CALLOSOTOMY

Interhemispheric coherence analysis of scalp electroencephalograms (EE Gs) in three intractable epileptic patients before and after surgical section of the anterior part of the corpus callosum was performed. Equ idistant EEG periods recorded under resting conditions free of interic tal epileptic activity and periods with generalized spike-and-wave dis charges were investigated. Mean coherence values for five frequency EE G bands (delta, theta, alpha, beta 1 and beta 2) before and after corp us callosotomy were compared with each other and statistically evaluat ed. Anterior callosotomy led, in all cases, to a decrease of interhemi spheric EEG coherence in most localizations, with the most profound de creases in the region corresponding to the section. These results supp ort the hypothesis that the corpus callosum plays an important role in resting interhemispheric integration and EEG synchronization, similar to its central role in propagation of specific epileptic activity.