Procedural learning is a basic mechanism for acquisition of basic motor and cognitive skills. Optimizing this process using both training strategies and innovative technology is of great importance in rehabilitation of patients with traumatic brain injury (TBI), an important cause of severe disability. Recently an expanding body of evidence indicated that trans-Cranial Direct Current Stimulation (tDCS) may positively affect procedural learning.

1. Characterize the effect of tDCS on motor skill learning in healthy adults using the finger-to-thumb opposition sequence paradigm (FOS). 2. Compare the findings to those of sub-acute TBI patients.

Thirty healthy and ten sub-acute TBI participants were included in a randomized double-blind, controlled trial. Participants were trained to perform a finger opposition task. The study group (20 participants) received anodal stimulation over the motor cortex contralateral to the performing hand, and the control group (20 patients) received “sham” stimulation. Performance (speed and accuracy) were tested before, immediately after and 24h post-training. Retention was tested one week later.

tDCS stimulation resulted in increased speed with no accuracy trade-off in healthy participants compared to controls, in the consolidation (37.4% vs. 30.6% improvement compared with initial speed) and retention stages (41.9% vs. 37.8%). The relative effect of tDCS was larger in the TBI group in both consolidation and retention stages (1.32 and 1.27, respectively). However, neither effects reached significance.

Our results are in line with previous findings that showed a positive effect of tDCS on learning but largre cohort studies are needed to substantiate this claim.