Estimation of phase synchronization in symmetric EEG channels

The problem of determining the symmetry of the brain electrical activity is considered. The new quantitative measure of symmetry in brain electrical activity for two hemispheres is proposed on the basis of mean values of phase synchronization for real and surrogate EEG. Experimental results of measuring symmetry of electroencephalographic signals from healthy and epileptic persons are presented, showing substantial differences in synchronicity revealed for two cases.