A New Approach to Evaluation of Electroencephalograms Inter-Channel Phase Synchronization

Abstract

Widely used methods of evaluation electroencephalogram (EEG) signals coherence have well-known drawbacks associated with the averaging of the evaluation of coherence in non-overlapping time periods and/or the wide frequency ranges, and the influence of the evaluation of amplitude modulation and noise. The report considers a new approach to the evaluation of phase coherency of EEG signals, consisting of the calculation of the phase of signals wavelet spectra at the points of the ridges. These points, under certain conditions, have property of phase stationarity. In this case, it is not required to conduct mentioned averaging. Evaluations of inter-channel EEG phase coherency using cognitive and motor tests by healthy subjects and patients after traumatic brain injuries are considered. This method allows to distinguish the phase-coupled pairs of EEG leads from uncoupled ones and to determine the phase-coupled pairs of leads specified for a certain test of the EEG record.