Comparative frequency analysis of single EEG-evoked potential records.

The aim of this study is to expand our previous results on the important relation between the spontaneous EEG and EPs (Basar et al. 1976 a,b). These previous results were obtained from single recordings of combined EEG-EP epochs by comparing the rms-magnitude of the spontaneous EEG prior to stimulus with the maximal amplitude of the response. Both were pass-band-filtered by means of the response adaptive filter, determined according to the band limits of the studied selectivity channel. In this earlier analysis, although the relation between the amplitudes of EEG and EP components in various frequency channels could be determined in the time domain, no exact statement could be made (1) on possible relations between the frequency distributions of spontaneous and evoked activities of a given brain centre, nor (2) on the phase relationships between the electrical activities of various brain structures. These gaps are filled in our present report with the further analysis of the EEG-EPograms simultaneously recorded from 5 different brain structures.