[Asymmetry of power in the EEG rhythms as a parameter of the brain function]

Comparison of power asymmetry (PA) has shown that low PA values occurred in the posterior cortical parts in adult examinees free of focal brain pathology, in anterior and posterior cortical parts in children and in patients with affected left hemisphere. In view of immaturity of the brain and unbalanced subcortical-cortical relationships in children there was enhanced functional activity of diencephalo-truncal structures. It is suggested that in patients with damaged left hemisphere functional activity of the right hemisphere dominates, therefore dominates functional activity of synchronizing diencephalo-truncal structures. High interhemispheric asymmetry was detected in anterior parts of the cortex in patients free of focal brain pathology as well as in anterior and posterior parts of the neocortex in patients with damaged right hemisphere. This can be explained by prevalence of activating stem structures in brain functioning. Damage to the right hemisphere affects more synchronizing truncal structures and intact left hemisphere becomes leading in CNS activity. This hemisphere has primarily functional relations with activating stem structures. Thus, the value of interhemispheric asymmetry of EEG biopotentials' powers may characterize brain function forming in participation of nonspecific stem system regulating functional condition of the brain.