Event-related alpha oscillations are functionally associated with P300 during information processing.

Recent findings indicate that the electroencephalographic alpha (7-14 Hz) activity is functionally involved in cognitive brain functioning, but the issue of whether and how event-related alpha oscillations may relate to the processes indexed by the P300 component of the event-related brain potentials (ERPs) has not been addressed. The present study assessed the effect of auditory oddball task processing on slow (7-10 Hz) and fast (10-14 Hz) alpha activity from the P300 latency range. ERPs from mentally counted targets (20%) and uncounted non-targets (80%) were recorded at Fz, Cz, and Pz in nine subjects Single-sweep phase-locking, power of phase-locked, and power of non-phase-locked alpha responses during P300 activity were quantified. The results demonstrated that larger and more synchronized phase-locked fast alpha components at anterior (frontal-central) locations, with reduced non-phase-locked slow alpha responses at the parietal site were produced by targets relative to non-targets. Because the simultaneously recorded P300 and alpha activity manifested a similar sensitivity to the oddball task, event-related alpha appears to be functionally associated with the cognitive processing demands eliciting P300. Also, evidence is provided for the functional involvement of frontally synchronized and enhanced alpha oscillations in task processing.