Search for Functional Markers of the Hippocampus Including in the Pathological Process

Abstract

We studied the features of EEG and visual memory processes in 27 patients with a mediobasal regions extracerebral tumor of right and left hemispheres. According to neuroimaging (MRI) and morphometry, the degree of hippocampus involvement in pathological process was assessed. The predominant concentration of irritative-epileptiform signs in the affected hemisphere, as well as the presence of atypical alpha-rhythm episodes in the tumor projection zone, were classified as EEG markers of tumor compressive effect on the hippocampus. Signs of non-identical involvement of the right and left hippocampi in the pathological process were found in the form of a predominance of irritative signs in the left hemisphere throughout the group as a whole. Equivalent dipole sources (EDS) of atypical alpha rhythm are more confined to hippocampal structures than irritative EEG patterns. Neuropsychological testing of visual memory did not reveal significant disturbances in memory processes at this stage of the disease.