Noninvasive Brain Stimulation over the M1 Enhances Bimanual Force Control Ability: A Randomized Double-Blind Sham-Controlled Study

Well-coordinated bimanual force control is common in daily life. We investigated the effects of anodal transcranial direct current stimulation (tDCS) over the primary motor cortex on bimanual force control. Under a cross-over study, young adults (n = 19; female = 6, male = 13) completed three bimanual force control tasks at 5%, 25%, and 50% of bimanual maximum voluntary force (BMVF) before and after real or sham tDCS. Real tDCS enhanced accuracy at all BMVF, reduced variability at 5% BMVF, and increased coordination at 5% BMVF. Real tDCS improved force control at 5% and 25% BMVF, and especially increased bimanual coordination at 5% BMVF. These findings might have implications for establishing interventions for patients with hand force control deficits.