Partitioning response inhibition by its latency, extent, and electrophysiological correlates

Abstract

Inhibition is one of the core concepts in cognitive neuroscience, referring to a higher-order control mechanism that can arrest or cancel the output of other functional systems. Inhibition of motor responses is assumed to serve as a proxy for cognitive inhibition, and impaired motor inhibition may thus constitute an endophenotype for at-risk behavior regarding poor impulse control and related psychiatric conditions. The current thesis challenges the account of a single central inhibition node by testing potential partitioning schemes of response inhibition into multiple counterparts within the motor system. First, behavioral and electrophysiological indices were compared between the most common response inhibition tasks, i.e., the go/no-go and stop signal tasks, and it was found that suppressed behavior in these tasks can be achieved via separable mechanisms. Secondly, hypothetical partitioning schemes between fast global and slow selective inhibition mechanisms were tested. While no conclusive evidence was found in support of such a dissociation in two independent studies, evidence was found for a pivotal role of proactive control in shaping the sensory, attentional, and motor parameters that play a role in successful inhibition. Altogether, the results suggest that action cancellation may be achieved via dynamic interactions within the motor control system incorporating action planning, selection, and inhibition, which further interacts with the proactive goal-driven cognitive system.