DENSE SENSOR ARRAY TOPOGRAPHY OF THE EVENT-RELATED POTENTIAL TO TASK-RELEVANT AUDITORY-STIMULI

High spatial density recording and better topographic mapping algorith ms have improved the spatial resolving power of the event-related pote ntial (ERP), adding to its already excellent temporal resolution. This study used a 64 channel recording array and spherical spline interpol ation to create topographic descriptions of the voltage and current de nsity scalp distributions of the ERP in an auditory oddball paradigm. Frequent (standard) and infrequent (target) tones were presented at a rate of one every approximately 2500 ms to a group of 20 college under graduates in passive Listening and active (count the infrequent tones) task blocks. ANOVAs and topographic analyses were performed on the pr imary deflections in the 'late' portion of the ERP: the P1, N1, P2, N2 and P3. A target minus standard difference wave was also created for each task. The difference wave contained a mismatch negativity (MMN), an N2b and a P3d. The MMN did not differ between the passive and activ e tasks and had a topography similar to the N1; also the difference wa ve P3d was topographically similar to the target P3. The N2b, which oc curred only to targets in the active condition, and was the first inde x of target detection, had a scalp distribution consistent with genera tion in frontal and superior temporal cortex, suggesting activity in c ortical areas of selective attention and auditory stimulus representat ion. (C) 1998 Elsevier Science Ireland Ltd.