[Foci of pathological activity in the human brain and their influence on the spatial-temporal relationships of the EEG].

EEGs of 51 patients with focal brain lesions (tumor localized in brain hemispheres) were analyzed. Coherence functions were calculated between the EEG recorded from the intact and lesioned hemispheres and three-dimensional analysis of the delta-wave "source" localization was conducted. The revealed delta-wave "sources" localized in the perifocal region of the lesioned hemisphere demonstrated its dynamic properties and a tendency for fluctuations. Changes in the delta-wave "source" pattern were correlated with the EEG coherence values neither in the lesioned nor in the intact hemisphere. The focus of pathological activity produced the changes in EEG coherence and its interhemispheric asymmetry. In the majority of cases (72%), the mean level of intrahemispheric coherence at the side ipsilateral to the pathological focus was lower than the normal mean level, and the mean level of EEG coherence in the intact hemisphere was increased.