Phase synchronization dynamics in filtered EEG signals

The phase synchronization dynamics in filtered EEG signals was studied in a visual-motor task in which the subjects were tracking a discretely moving spot in regular (RM) or Brownian (BM) time-step. A sudden "STOP" signal appeared during the trial which warned the subject to change the direction of the spot movement. Phase was measured from narrow frequency bands (f +/- 2.5 Hz) by convolution with a complex Morlet wavelet designed for f. Frequency f was chosen form theta, alpha, beta and gamma bands (6, 10, 17 and 37 Hz respectively). It was found that the mean number of synchronized pairs depends only on the frequency band; while the dominance of phase synchronization (the number of derivations with which each of them is synchronized simultaneously) depends on the frequency band and on the type of spot movement as well. The latter method provides complex characteristics of the phase synchronization dynamics. The analysis of dominance is sensitive, it provides information about the localization of the dominance on the scalp and it estimates the intensity of participation of each area in the synchronization process.