N2, P3 and the lateralized readiness potential in a nogo task involving selective response priming

Motor inhibition and its correlates in the event-related potential (ERP) are often studied in go/nogo tasks. However, go and nogo trials differ in their motor and their attentional requirements, rendering an interpretation of corresponding changes in ERP components difficult. As an alternative strategy to study motor inhibition, a hybrid choice-reaction go/nogo procedure involving selective response priming was used. Eighteen subjects performed the task. Response time (RT) and error measures as well as the lateralized readiness potential (LRP) indicated that responses were primed by flanker stimuli that were associated with one of the two possible responses. In nogo trials, selective response priming influenced the N2 amplitude whereas the P3 amplitude was unaffected. Because the N2 appeared irrespective of whether an erroneous response was correctable (in go trials) or not (in nogo trials), we conclude that the N2 reflects either the detection or the inhibition of an inappropriate tendency to respond.