C Pantev, C Eulitz, S Hampson, B Ross, and Larry E Roberts (1996)
The Auditory Evoked "Off" Response: Sources and Comparison with the"On" and the "Sustained" Responses
Ear & Hearing, 17(3):255-265.
Objective: It is well known that tone bursts elicit a prominent N1/P2 complex in the auditory evoked potential (the on-response), but less is known about a morphologically similar complex (the off-response) that can be recorded under suitable stimulus conditions. The interaction between the two responses indicated that the responses were not physiologically independent. The present experiment employed neuromagnetic methods to determine the cortical sources of N1 and P2 on- andoff-responses and their relation to other events observed in the auditory evoked field.
Result: The present study is unique in that several components of the complex auditory evoked response (P1, N1on, P2on, sustained-field, N1off, P2off) were recorded and localized in the same subjects and in the same experiment. The source coordinates obtained for N1 and P2 on- andoff-responses indicated that the two responses are generated by overlapping cortical regions. Sources for the P2 components were situated anterior and medial to sources for the N1 components and were indistinguishable from sources for the auditory sustained-field. An early P1on event preceded the N1on (but not the N1off) response and was spatially indistinguishable from the N1on response. The equivalent source strength was greater for N1on and P2on sources compared with N1off and P2off sources.