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Updated: Mar 20, 2026
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Intracortical Inhibition Within the Primary Motor Cortex Can Be Modulated by Changing the Focus of Attention
Published on: September 11, 2017
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Sex-based differences in corticospinal excitability and inhibition.
Alicia M Kells1, Alexandra N Pauhl1, Anita D Christie1
1Faculty of Health Sciences, School of Kinesiology, Western University, London, Ontario, Canada.
Experimental Physiology
|March 19, 2026
Summary
Males and females show similar corticospinal excitability. However, males exhibit greater short-interval intracortical inhibition (SICI) and long-interval intracortical inhibition (LICI) than females, suggesting sex is a factor in some TMS measures.
Area of Science:
- Neuroscience
- Human Physiology
Background:
- Transcranial magnetic stimulation (TMS) is a non-invasive technique used to probe the human motor system.
- Understanding sex-based differences in neural excitability and inhibition is crucial for interpreting TMS findings.
Purpose of the Study:
- To investigate sex-based differences in corticospinal excitability and inhibition using various single- and paired-pulse TMS measures.
- To determine if sex influences specific TMS-derived metrics of motor cortex function.
Main Methods:
- Thirty participants (15 males, 15 females) underwent single- and paired-pulse TMS.
- Electromyography recorded responses from the first dorsal interosseous muscle.
- Measures included motor-evoked potential (MEP), intracortical facilitation (ICF), cortical silent period (CSP), short-interval intracortical inhibition (SICI), and long-interval intracortical inhibition (LICI).
Main Results:
- No significant sex differences were found in motor-evoked potential (MEP) or intracortical facilitation (ICF).
- Males demonstrated significantly greater short-interval intracortical inhibition (SICI) and long-interval intracortical inhibition (LICI) compared to females.
- Cortical silent period (CSP) did not show significant differences between sexes.
Conclusions:
- Sex does not appear to influence corticospinal excitability measures like MEP and ICF.
- Sex-based differences are evident in specific inhibitory TMS measures, namely SICI and LICI.
- These findings highlight the importance of considering sex when interpreting certain TMS-derived measures of corticospinal inhibition.
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