The Use of Direct Current Stimulation to Investigate the Role of Each Hemisphere in Motor Learning of Reaching Task

Transcranial Direct Current Stimulation (tDCS) can improve or impair the function of the brain. This has turned tDCS into a tool that can be used for evaluation of hemispheric specialization in motor programming and final position accuracy, as components of motor control and learning.
Two different studies were designed. 53 male students (21.34±1.61 years) and 43 male students (20.442±1.578 years) were participated in the first and second studies, respectively. Participants were randomly assigned into four groups. C3 /C4 and F3/F4 areas were stimulated with the 2mA current in the first and second studies, respectively. The Repeated Measure test was used to analyze data.
In the first experiment, left M1 group (left anode/right cathode stimulation) significantly improved motor programming compared to the other groups. In the second experiment, the right dorsolateral prefrontal cortex group (right cathode/left anode) significantly decreased final position accuracy compared to the other groups.
Our data suggested that the left hemisphere is specialized for motor programming whereas the right hemisphere is specialized for final position accuracy. These results are interpretable with hybrid motor control hypothesis.