Intensity-Dependent Effects of 4-week Transcranial Direct Current Stimulation on Motor Learning in Healthy Young Adults

Intensity-Dependent Effects of 4-week Transcranial Direct Current Stimulation on Motor Learning in Healthy Young Adults

The goal of this clinical trial is to investigate the effects of different intensities of transcranial direct current stimulationover primary motor cortex on motor learning in healthy adults. The main question it aims to answer is:

Which intensity of tDCS can best improve motor learning? Researchers will compare 1 mA, 2 mA, and 3 mA tDCS to sham tDCS to see which intensity of tDCS is most effective in improving the ability of motor learning.

Participants will be randomly divided into four groups and receive 4 different intensities of tDCS(1 mA, 2 mA, 3 mA and sham tDCS),and will be blinded to the type of tDCS they received. We hypothesized that anodal tDCS at 2 mA would produce the most substantial improvement in motor learning.

The present study aimed to investigate the effects of different intensities of tDCS-specifically 1 mA, 2 mA, and 3 mA-on motor learning in healthy adults. Both the acute effects following a single tDCS session and the cumulative effects after a 4-week intervention (10 sessions) were evaluated. Additionally, the study aimed to determine whether improvements in motor learning induced by 4 weeks of repeated tDCS would be sustained one week after completion of the intervention. We hypothesized that anodal tDCS at 2 mA would produce the most substantial improvement in motor sequence learning, both following a single session and after a 4-week intervention, compared to 1 mA, 3 mA, and sham stimulation. Furthermore, we expected that the motor learning gains observed in the 2 mA group would be sustained one week post-intervention, indicating the persistence of tDCS-induced effects. In contrast, we anticipated minimal improvement in the 1 mA group due to insufficient stimulation intensity, and no additional or even reduced benefits in the 3 mA group compared to the 2 mA group.

Inclusion Criteria:

1. age between 18 and 25 years; (2) normal or corrected-to-normal vision; (3) no history of pregnancy, cardiovascular disease, other physical impairments or illnesses, and no personal or family history of mental illness; (4) no implantation of any internal or external medical devices; and (5) right-handedness.

Exclusion Criteria:

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