A single sweep analysis of the theta frequency band during auditory oddball task

The P300 component and the oscillatory 4–7 Hz electroencephalographic activity of auditory event-related brain potentials (ERPs) were assessed to study differences between passive and oddball task conditions. Theta responses from 15 adults were analyzed for single-sweep amplitude, phase-locking, and enhancement against prestimulus activity. ERPs were characterized by enhanced and strongly phase-locked theta oscillations in the early (0–300 ms) post-stimulus epoch, with only the late (300–600 ms) theta responses at Fz and Pz affected by the oddball condition. P300 was strongly associated not only with the concurrent theta oscillations but also with the evoked theta activity preceding P300 (0–300 ms). It is concluded that single theta response parameters can reveal specific functional differences between passive and oddball conditions, and there is a strong relationship between the theta frequency component and the time-domain P300 ERP component