Motor cortex contribution to dynamic force regulation in the index finger revealed by TMS interference.

Brief interference over the motor cortex opposite the active hand disrupted precise finger-force control more than same-side stimulation. This maps a motor-control mechanism in healthy adults and is not evidence that rTMS improves movement.

Kadosh A, Wonderman Bar Sela O, Ofir Geva S, Muhana A, Frenkel-Toledo S, Soroker N, Mawase F.
Journal of neurophysiology · Publication date: 2026-09-23
Added to site: 2026-09-26
DOI: 10.1152/jn.00057.2026

Electronic publication date verified in Europe PMC; first indexed 2026-09-24. This source date is separate from the site's addition date.

Modalities

TMS, rTMS, Motor physiology

Clinical focus

Force regulation, Motor cortex, Sensorimotor control

Population

Healthy adults completing an isometric index-finger force-tracking task

Sample

11 healthy adults

Intervention / method

Two-second trains of 10 Hz online rTMS were delivered over contralateral primary motor cortex, ipsilateral primary motor cortex or a midline control site while participants tracked low-force and high-force targets

Comparator

Contralateral versus ipsilateral versus midline stimulation, with no-TMS observations included in the reported comparisons

Clinician summary

Stimulation site significantly affected accuracy, consistency and force smoothness, with all omnibus p values below 0.0022. Contralateral M1 disruption exceeded ipsilateral M1 and no TMS; the contralateral-versus-ipsilateral difference in force smoothness was larger at 60% than 20% maximal voluntary contraction.

How to interpret the findings

Small healthy-volunteer sample and a brief laboratory task limit generalization to patients, rehabilitation or everyday grasp. The intervention was used to transiently disrupt function, not as treatment. The checked abstract did not provide effect sizes, confidence intervals, adverse-event details or competing-interest disclosures.

Equipment and disclosures

Online 10 Hz rTMS over motor-cortex and midline targets; stimulator and coil models were not available in the checked abstract.

Europe PMC lists Israel Science Foundation grant 2484/23. Competing-interest details were not available in the checked indexed record.

Related evidence

Compare findings from the same clinical area, including mixed results.