Ipsilateral and contralateral correlations between EEG and EP principal components.

Correlations between EP and EEG principal components are reported. The signs of the correlations appear to depend on 3 factors: frequency of the EEG, whether the EP and EEG were measured from ipsilateral or contralateral leads, and EP latency. Correlations are negative between EP amplitude (at 100-500 msec) and EEG alpha from ipsilateral leads. When the EP measurements are from leads contralateral to the eEG alpha measurements, the correlations are positive. EEG beta, however, shows the opposite pattern (ipsilateral correlations are positive, while contralateral correlations are negative). Finally, there is some indication of higher ipsilateral correlations for earlier EP components (as opposed to lower correlations for later EP components), and higher contralateral correlations for later EP components. The EPs and EEGs were taken during separate experimental conditions as part of the same experimental session. The original EP measurements were amplitudes (N100, P150, N200, and P300) to words flashed on a television screen, as S1 of a CNV paradigm. The EEGs were 4 sec epochs taken immediately upon television presentation of a word or picture problem.