The effects of lesions to subcortical conducting pathways on the electrical activity of the human cerebral cortex.

Simultaneous assessment, during the neurorehabilitation process, of electroencephalographic and neurological data, along with computerized tomography and computerized emission tomography data from patients suffering from sequelae due to ischemic insult allowed the organic origin of a number of EEG phenomena to be identified. These studies showed that lesions to the conducting pathways between the cortex and subcortical structures due to circulatory pathology in the territory of the middle cerebral artery were accompanied by local changes in the electrical activity of the cortex, mainly in the form of polymorphic waves in the theta and delta frequency ranges, along with groups of theta oscillations. The nature of slow-wave oscillations depended on the extent of the lesions and the severity of the blood supply loss in the affected area. Reductions in the size of the lesion focus and improvements in blood supply during rehabilitation were accompanied by changes in the nature of local abnormalities in cortical electrical activity: polymorphic slow-wave activity was replaced by sharp waves in the alpha and theta frequency ranges. Localization of changes in the caudal part of the cortex was an unfavorable prognostic factor for patients with ischemic insult, in terms of recovery of motor function.