Facilitation of Implicit Motor Learning by Weak Transcranial Direct Current Stimulation of the Primary Motor Cortex in the Human

TLDR

Transcranial direct current stimulation can modulate motor cortical excitability, and such excitability changes are known to accompany motor learning. The study applied contralateral tDCS to the primary motor, premotor, or prefrontal cortex while participants performed a serial reaction time task. Anodal tDCS of the primary motor cortex improved performance on the serial reaction time task, indicating its role in acquisition and early consolidation of implicit motor learning, while stimulation of premotor or prefrontal areas had no effect.

Abstract

Abstract Transcranially applied weak direct currents are capable of modulating motor cortical excitability in the human. Anodal stimulation enhances excitability, cathodal stimulation diminishes it. Cortical excitability changes accompany motor learning. Here we show that weak direct currents are capable of improving implicit motor learning in the human. During performance of a serial reaction time task, the primary motor cortex, premotor, or prefrontal cortices were stimulated contralaterally to the performing hand. Anodal stimulation of the primary motor cortex resulted in increased performance, whereas stimulation of the remaining cortices had no effect. We conclude that the primary motor cortex is involved in the acquisition and early consolidation phase of implicit motor learning.