Anodal transcranial direct current stimulation (tDCS) over premotor and parietal cortex improves upper limb...

Proprioception plays a critical role in motor control and is often impaired following orthopedic or neurological damage. Non-invasive brain stimulation methods, such as transcranial direct current stimulation (tDCS), could potentially be used to modulate proprioceptive processing and help recovery. Among cortical areas, the premotor cortex (PMC) and posterior parietal cortex (PPC) are key regions involved in proprioceptive processing. We investigated the effects of tDCS delivered with the anode positioned over the right PMC and PPC on active joint position sense (AJPS) in healthy adults. Forty-five right-handed participants were randomly assigned to receive anodal tDCS targeting either PMC, PPC, or a SHAM tDCS protocol. Stimulation was applied for 20 min per day, over five consecutive days. AJPS of the elbow flexion and shoulder internal and external rotation, both with the arm ipsilateral and contralateral to the stimulation, were assessed before and after the 5 days protocol. Anodal tDCS stimulation of both PMC and PPC induced significant reductions in angular error compared to SHAM. We found no significant differences between the ipsilateral and contralateral arms or across movements, supporting that tDCS can have a broad, positive impact on proprioceptive accuracy in healthy individuals. Our results suggest that PMC and PPC could provide promising targets for neuromodulatory interventions aiming at enhancing proprioceptive sense.