Sex‐based differences in corticospinal excitability and inhibition

Abstract The purpose of this study was to perform a novel exploration of sex‐based differences in various single‐ and paired‐pulse transcranial magnetic stimulation (TMS)‐based measures of corticospinal excitability and inhibition. Thirty participants (15 females) attended one laboratory visit where responses evoked by single‐ and paired‐pulse TMS were recorded using electromyography from the first dorsal interosseous muscle. Excitability was assessed via the motor‐evoked potential (MEP) and intracortical facilitation (ICF). Inhibition was assessed via the cortical silent period (CSP), short‐interval intracortical inhibition (SICI), and long‐interval intracortical inhibition (LICI). Each measure was compared between sexes. Overall, males and females did not significantly differ in excitability (MEP: P = 0.070; ICF: P = 0.194). Males displayed significantly greater inhibition compared to females for the SICI (P = 0.016) and LICI (P = 0.003) measures but not CSP (P = 0.612). These findings suggest that sex may be an important consideration for some (SICI and LICI), but not all TMS‐based measures of corticospinal excitability and inhibition.