The study pertains to new approaches in the study of corrlations between the EEG data and the degree of lesions in the nuclei of the reticular formation in ischemic strokes due to occlusive processes in the vertebrobasillar system. In all cases, because of disorders of vital functions, the authors convened artificial lung ventilation which permitted to prolong the life of the patient and to study the dynamics of the EEG. In 10 lethal cases the brain stem was studied on a series of continuous preparations to determine the degree of lesions in the nuclei of the reticular formation in the pons Varoli and medulla oblongata in ischemic foci. It was not possible to establish significant differences in the indices of bioelectric brain activity in lesions of reticular nuclei of pons Varoli and medulla oblongata. The authors stress the necessitity of reconsidering the existing concepts of a dependence of EEG changed parameters upon the localization of the focus in the brain stem.