Event-related changes of background electroencephalogram during contingent negative variation paradigm.

The autoregressive model was applied to the background electroencephalogram during the tone(S1)-tone(S2)-respond contingent negative variation paradigm under eyes-open condition. The EEG data were obtained at the scalp sites of Fz, Cz, and Pz in seven normal males. During the first half of the interstimulus interval (ISI) of 2.5 s, Fz-dominant excitatory process was suggested in concordance with an orienting response to stimulus 1. In the second half of the ISI, Pz-dominant inhibitory process was considered. The stimulus 2 presentation and the required motor response promoted the Pz-dominant process.