[Are cognitive processes related to the EEG alpha phase? An experimental study using P300].

Different models have been developed in the past to explain the functional significance of the EEG alpha rhythm. This rhythm has been viewed as an expression of a scanning mechanism, of an inner clock or of an excitability cycle. Based on these conceptions, several older works dealing with EEG alpha phase and reaction time suggest that the EEG may also serve as a gating mechanism for cognitive information processing. The purpose of this investigation was therefore to determine the existence of a possible correlation between P300 and the background EEG. P300 was used as a neuroelectrical correlate of a cognitive decision-making process. However no significant relationship between P300 latency period and EEG alpha phase was found. The variability of P300 can therefore not be explained in this way.