Effects of Different Repetitive Transcranial Magnetic Stimulation Targets for Enhancing Motor Learning: A Single-Blind Randomized Controlled Trial.

Abstract

Background: The primary motor (M1) and somatosensory (S1) cortices play a key role in motor learning (ML), but the physiological mechanisms underlying learning in these regions remain unclear. This study aimed to evaluate the effect of high-frequency repetitive transcranial magnetic stimulation (rTMS) applied over S1 or M1 to enhance use-dependent and reinforcement-like ML in healthy participants.

Methods: A single-blind, randomized controlled trial (RCT) was conducted with 60 healthy participants, randomly assigned to receive rTMS over M1, S1, or sham. Participants underwent a 10-day motor training protocol involving an arbitrary visuomotor association (AVMA) task to promote reinforcement learning and the Purdue Pegboard Test (PPT) to promote use-dependent learning, always after rTMS. The primary outcome measure was the number of pegs placed in the PPT, and the secondary outcome was the response accuracy during a forced response (FR) version of the AVMA. Assessments were conducted at baseline, mid-intervention (t1), postintervention (t2), and at 1-month follow-up (t3).

Results: For use-dependent learning on the PPT, S1 stimulation outperformed sham at t1 (right hand), t2 (both hands), and t3 (both hands). M1 stimulation showed no significant differences versus sham. For reinforcement learning on the forced response-AVMA (FR-AVMA), no active group differed from sham; however, S1 and M1 showed opposite numerical tendencies at t3 (S1 trending better, M1 worse), yielding a significant S1-M1 contrast.

Conclusion: These findings suggest that rTMS over S1 may enhance use-dependent ML, while the divergent S1 and M1 tendencies in reinforcement-like learning warrant further, adequately powered investigation, with implications for future research in both healthy and clinical populations.

Trial registration: ClinicalTrials.gov identifier: NCT06262425.