A psychophysiological analysis of inhibitory motor control in the stop-signal paradigm

We examined two Potential inhibitory mechanisms for stopping a motor respon se, Participants performed a standard visual two-choice task in which visua l stop signals and no-go signals were presented on a small proportion of th e trials. Psychophysiological measures were taken during task performance t o examine the time course of response activation and inhibition. The result s were consistent with a horse race model previously proposed to account fo r data obtained using a stop-signal paradigm. The pattern of psychophysiolo gical responses was similar on stop-signal and no-go trials suggesting that the same mechanism may initiate inhibitory control in both situations, We found a distinct frontal brain wave suggesting that inhibitory motor contro l is instigated from the frontal cortex. The results are best explained in terms of a single, centrally located inhibition mechanism. Results are disc ussed in terms of current neurophysiological knowledge. (C) 2001 Elsevier S cience B.V. All rights reserved.