Abstract
Inhibitory control is the ability to suppress inappropriate movements and unwanted actions, allowing to regulate impulses and responses. This ability can be measured via the Stop Signal Task, which provides a temporal index of response inhibition, namely the stop signal reaction time (SSRT). At the neural level, Transcranial Magnetic Stimulation (TMS) allows to investigate motor inhibition within the primary motor cortex (M1), such as the cortical silent period (CSP) which is an index of GABAB-mediated intracortical inhibition within M1. Although there is strong evidence that intracortical inhibition varies during action stopping, it is still not clear whether differences in the neurophysiological markers of intracortical inhibition contribute to behavioral differences in actual inhibitory capacities. Hence, here we explored the relationship between intracortical inhibition within M1 and behavioral response inhibition. GABABergic-mediated inhibition in M1 was determined by the duration of CSP, while behavioral inhibition was assessed by the SSRT. We found a significant positive correlation between CSP’s duration and SSRT, namely that individuals with greater levels of GABABergic-mediated inhibition seem to perform overall worse in inhibiting behavioral responses. These results support the assumption that individual differences in intracortical inhibition are mirrored by individual differences in action stopping abilities.
Highlights
While its latter part is entirely mediated by motor cortical postsynaptic inhibition[24,25]
Raw data were processed via a customized R software for Windows, using the code for the analysis provided by Verbruggen and C olleagues[9]
The cortical silent period (CSP) duration was defined as the time elapsed between the offset of the motor-evoked potentials (MEPs) and the time at which the post-stimulus EMG activity reverted to the pre-stimulus level
Summary
While its latter part is entirely mediated by motor cortical postsynaptic inhibition[24,25]. Quite a few s tudies[14,35,36,37,38,39,40,41,42] have investigated whether and to what extent individual levels of resting-state SICI and LICI measured offline might reflect individual differences in the efficiency of the inhibitory process, indexed by the length of the Stop Signal Reaction Time (SSRT) Taken together, these studies support the hypothesis that trait-like individual differences in the neurophysiological markers of intracortical inhibition (and SICI in particular) can predict an individual’s actual behavioral motor inhibition c apacities[14].
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