Sex-based Differences In Corticospinal Excitability And Inhibition
Bibliographic record
Abstract
Males and females differ in anatomy and physiology at many levels of the body, including the brain, which could influence the communication from the brain to the muscle, impacting movement control. However, sex-based differences in excitability and inhibition within the corticomotor pathway have not been extensively studied. PURPOSE: To examine sex-based differences in corticospinal excitability and inhibition. METHODS: Thirteen individuals (23.9 ± 2.1 yrs) 8 males, 5 females, participated in the present study. Males were tested around the same time of day in the afternoon and females were tested during the same phase of their menstrual cycle (mid-follicular; day 7.6 ± 0.5). Electromyography was recorded from the first dorsal interosseous muscle in response to TMS of the contralateral motor cortex. Single-pulse stimuli were used to assess excitability via the motor-evoked potential (MEP) and inhibition via the cortical silent period (CSP). Additionally, paired-pulse stimuli were used to assess excitability via intracortical facilitation (ICF) and inhibition via short-interval intracortical inhibition (SICI) and long-interval intracortical inhibition (LICI). All outcome measures were compared between males and females. RESULTS: Males had similar levels of excitability compared with females via MEP (2.9 ± 1.0 mV vs 3.06 ± 1.37 mV; p = 0.86; d = 0.11) and ICF (68.0 ± 70.7% vs 36.7 ± 100.1%; p = 0.52; d = 0.38). Inhibition was also similar between males and females, as assessed by CSP duration (124.3 ± 30.6 ms vs 91.6 ± 43.9 ms; p = 0.16; d = 0.90), SICI (-62.9 ± 26.0% vs -59.3 ± 30.5%; p = 0.82; d = 0.13), and LICI (-81.4 ± 18.2% vs -71.6 ± 26.4%; p = 0.47; d = 0.46). CONCLUSION: No significant differences in corticospinal excitability or inhibition were observed between males and females, when controlling for lower hormone fluctuation timepoints. However, considering effect sizes, CSP may reach significance with a greater sample size. Natural Sciences and Engineering Research Council of Canada (NSERC) RGPIN-2019-05127
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.005 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".