[Interhemispheric EEG-asymmetry in 5--7-year-old children]

Interhemispheric asymmetry (IHA) of the theta-rhythm in the frontal, central, parietal, occipital and temporal cortical areas was studied in 5-7 years old children. The children performed visual-spatial (drawing mosaic) and verbal (reciting, associative experiment) tasks. IHA was also estimated in the state of rest, when a child doesn't move with his eyes open. It is found that in the state of rest the theta-activity is predominant in the right hemisphere in all cortical areas. During performance of visual spatial tasks this correlation does not change significantly. During verbal activity IHA values shift towards the left hemisphere. These changes are mostly pronounced in the frontal and temporal cortical areas where the left-side asymmetry of the theta-activity is revealed. In the central areas no significant IHA is recorded; in the parietal and occipital areas the theta-rhythm is predominant in the right hemisphere. The data obtained suggest a functional specialization of the hemispheres in 5-7 years old children. The left hemisphere is more active during verbal activity whereas the right one plays the leading role both during visual-spatial activity and in the organization of the rest state.