Purpose: This study examined whether transcranial direct current stimulation (tDCS) of the primary motor cortex alters the response time in motor suppression using the stop-signal task (SST).
Methods: Forty healthy subjects were enrolled in this study. The subjects were assigned randomly to either the tDCS condition or sham control condition. All subjects performed a stop-signal task in three consecutive phases: without, during or after the delivery of anodal tDCS on the primary motor cortex (the pre-tDCS motor phase, on-tDCS motor phase, and after-tDCS motor phase).
Results: The response times of the stopping process were significantly lower in each SST motor phase during or after tDCS (p < 0.05) and shorter immediately during delivery of the tDCS, whereas there was no change after the delivery of tDCS compared to sham condition. In contrast, the response times of the going process were similar under the two conditions (p > 0.05). No subjects complained of any adverse symptoms or signs.
Conclusion: Anodal tDCS enhances voluntary going and stopping of movement in executive control. tDCS appears to be an effective modality to modulate motor suppression and its related dynamic behavioral changes in motor sequential learning.