Estimation of short-time cross-correlation between frequency bands of event related EEG.
Simultaneous variations of the event-related power changes (ERD/ERS) are often observed in a number of frequency bands. ERD/ERS measures are usually based on the relative changes of power in a given single frequency band. Within such an approach one cannot answer questions concerning the mutual relations between the band-power variations observed in different frequency bands. This paper addresses the problem of estimating and assessing the significance of the average cross-correlation between ERD/ERS phenomena occurring in two frequency bands. The cross-correlation function in a natural way also provides estimation of the delay between ERD/ERS in those bands. The proposed method is based on estimating the short-time cross-correlation function between relative changes of power in two selected frequency bands. The cross-correlation function is estimated in each trial separately and then averaged across trials. The significance of those mean cross-correlation functions is evaluated by means of a nonparametric test. The basic properties of the method are presented on simulated signals, and an example application to real EEG and ECoG signals is given.
Zygierewicz
J
J
Department of Biomedical Physics, Institute of Experimental Physics, Warsaw University, ul. Hoza 69, 00-681 Warszawa, Poland. jarekz@fuw.edu.pl
Mazurkiewicz
J
J
Durka
P J
PJ
Franaszczuk
P J
PJ
Crone
N E
NE
D000328:Adult; D001921:Brain / Q000502:physiology*; D003344:Cortical Synchronization / Q000379:methods*; D005071:Evoked Potentials / Q000502:physiology; D006801:Humans; D008297:Male