Connectivity of electroencephagraphic activities with bootstrap and imaginary part of the coherence

Analyses of the connectivity among electroencepha-graphic(EEG) time series can facilitate the understanding of the interactions between cerebral functional areas.A method based on the bootstrap and an imaginary part of the coherence was developed to analyze the connectivity and the information propagation during motor imagery.The results describing the information flow between the supplementary motor area(SMA),the contralateral premotor cortex(PMC),and the primary sensorimotor area(M1/S1) show that the subjects use kinetic motor imagery.The method is quite simple and effective,and can be further applied for connectivity studies of brain-computer interfaces and event-related potential.