Transcranial Evoked Potentials are Minimally Influenced by Afferent Feedback From Peripheral Muscle Contraction

First published online October 25, 2026. In 16 healthy volunteers, the EEG response after motor-cortex TMS appeared to be driven mainly by the brain's starting excitability state rather than sensory feedback from the resulting muscle twitch. This helps interpret a research measurement; it does not show a treatment benefit.

Marco M, Andrea G, Andrea F, Carlo P, Giorgio L, Rocchi L.
Neuroscience Bulletin · Publication date: 2026-10-25
Added to site: 2026-10-26
DOI: 10.1007/s12264-026-01729-9

First published online October 25, 2026. Added to Neurofeedback.com October 26, 2026.

Modalities

TMS-EEG, EEG, Electromyography

Clinical focus

TMS-evoked potentials, Peripheral sensory feedback, Cortical excitability

Population

Healthy right-handed adults without reported neurological or psychiatric disorders

Sample

16 volunteers, eight women and eight men; mean age 29.9 years

Intervention / method

Motor-cortex TMS-EEG was combined with electromyography and accelerometry; large- and small-output trials were compared, while separate electrical stimulation of the finger muscle isolated afferent feedback

Comparator

Within-person high- versus low-motor-output TMS trials and matched peripheral electrical-stimulation conditions

Clinician summary

Isolated muscle contraction produced delayed EEG responses after 65 ms that were much smaller and had different spatial and temporal profiles from TMS-evoked potentials. High- versus low-output trials differed in Bayesian analyses across predefined windows, including timings too early for reafference, although frequentist cluster comparisons were not significant. All participants tolerated the session and no side effects were observed.

How to interpret the findings

This was a small healthy-volunteer methods study of primary motor cortex stimulation. Bayesian and frequentist analyses did not give identical inferential emphasis, and the design cannot show that every TMS-EEG component or every target is free of sensory contamination. Results may not generalize to patients, other muscles, different intensities, other cortical targets or clinical protocols.

Equipment and disclosures

The full text names a Magstim Rapid2 stimulator, SofTaxic Optic neuronavigation, EEG, EMG and accelerometry equipment for this methods experiment. These tools are not compared as commercial products and none is attributed to BrainMaster.

The full text declares no conflicts of interest and reports open-access funding through the University of Cagliari under the CRUI-CARE agreement. No indexed correction, retraction or expression-of-concern relation appeared in the retained records; this is a bounded check. AI-assisted full-text source review.

Related evidence

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