Structural-Functional Characteristics of Brain Functioning on Performance and Imagination of Motor Tasks in Healthy People (EEG and fMRI studies)

Abstract

Bioelectrical (EEG) and hemodynamic (fMRI responses) reactions of the brain to motor tasks for the right and left hands and imaginary performance of those tasks were studied in 15 healthy right-handed subjects (21‐39 years old). In real movements, the main fMRI response was recorded in the central gyri of the contralateral (to the working hand) hemisphere. Activation zones were also seen in the supplementary motor area and the ipsilateral hemisphere of the cerebellum. The corresponding EEG showed increases in the coherence of the high-frequency alpha and beta frequencies in the activated hemisphere. Imagination of movements produced fMRI reactions which were highly variable in terms of extent and topography; weakening of responses was seen in the motor zone and cerebellum, with increased activation of subcortical structures in the parietal associative zones. Changes in the EEG in this situation were very variable; there were increases in the coherence of high-frequency alpha and beta oscillations, in the right hemisphere. Changes in spectral power were similar in real and imaginary movements and consisted of increases in the power and mean frequency of beta oscillations not confined to the activated hemisphere but also appearing in the left hemisphere. These reflected the nonspecific component of the responses.