Nonlinear Quadratic Phase Coupling on EEG based on 112-Dimension Spectrum

AIM: To learn about the quadratic phase coupling (QPC) behaviours of five different mental tasks of electroencephalogram (EEG) signals. Methods: by overcoming the shortcoming of power spectrum, which provides no phase information, and taking advantage of good characteristics of higher order spectra, a method referred to as 1¿-dimension spectrum (1¿-D spectrum) is proposed. Results: The results show that 1 ¿-D spectrum is capable of nonlinear QPC analysis on EEG, which is considered to be a non-Gaussian random process; and the QPC behaviours occur on all typical mental tasks although some slight differences exist between them. Conclusions: There exist the QPC behaviours on EEG mental tasks. The method proposed may indicate a new way to reveal nonlinear interactive couplings on EEG.