Early changes in corticomotor excitability underlie proactive inhibitory control of error correction

Converging evidence indicates that response inhibition may arise from the interaction of effortful proactive and reflexive reactive mechanisms. However, the distinction between the neural basis sustaining proactive and reactive inhibitory processes is still unclear. To identify reliable neural markers of proactive inhibition, we examined the behavioral and electrophysiological correlates elicited by manipulating the degree of inhibitory control in a task that involved the detection and amendment of errors. Restraining or encouraging the correction of errors did not affect the time course of the behavioral and neural correlates associated to reactive inhibition. We rather found that a bilateral and sustained decrease of corticomotor excitability was required for an effective proactive inhibitory control, whereas selective strategies were associated with defective response suppression. Our results provide behavioral and electrophysiological conclusive evidence of a comprehensive proactive inhibitory mechanism, with a distinctive underlying neural basis, governing the commission and amendment of errors. Together, these findings hint at a decisive role for changes in corticomotor excitability in determining whether an action will be successfully suppressed.SIGNIFICANCE STATEMENTResponse inhibition is a fundamental brain function that must be flexible enough to incorporate volitional goal-directed demands, along with rapid, automatic and well consolidated behaviors. Previous studies reflect a lack of consensus regarding the neural correlates subserving these two –proactive and reactive– distinct modes of inhibitory control. We combined electrophysiological recordings with behavioral measures within a paradigm of detection and correction of errors under two degrees of inhibitory control to identify genuine neural markers of proactive inhibitory control. We found evidence supporting a sustained and global –not selective– reduction of corticomotor excitability subserving successful proactive inhibition of motor responses. Our findings favor a distinctive mechanism of comprehensive inhibitory control to amend errors under a high degree of response competition.