Cortical Silent Period reflects individual differences in action stopping performance

Abstract

Inhibitory control is the ability to suppress unwanted actions. At the behavioral level, this ability can be measured via the Stop-Signal Task (stop-signal reaction time, SSRT). At the neural level, Transcranial Magnetic Stimulation provides electrophysiological measures of motor inhibition within the primary motor cortex (M1), such as the Cortical Silent period (CSP), a biomarker of proactive intracortical inhibition mainly mediated by GABAB receptors. Individual differences in this biomarker might contribute to behavioral differences in inhibitory control. Hence, we explored the relationship between intracortical inhibition and behavioral inhibition. Levels of intracortical inhibition were determined by measuring the length of individuals’ CSP, while inhibitory capacities were assessed by the SSRT. We found a significant positive correlation between CSP and SSRT, namely that individuals with greater GABABergic-mediated proactive inhibition seems to perform worse in inhibiting behavioral responses. These results suggest that individual differences in intracortical inhibition are mirrored by differences in motor-inhibitory ability.