Discussion
CORTEX
In the current study, we investigated whether VMI immediately changes motor performance and early stages of motor learning in healthy individuals. As a result, compared to pre, VMI promoted the early stage of motor learning with a higher improvement rate in ball-rotation task over post1 (immediately) and post2 (after 1 h) than the AO group. In addition, the VMI group in improvement phase 1 (post1−pre) showed significantly decreased brain activity in the left DLPFC and right PMC compared to the AO group. These results indicate that VMI immediately changes motor performance and brain activity and promotes the early stages of motor learning.The VMI group of improvement phases 1 and 2 (post1−pre and post2−pre) had a significantly higher improvement rate in the ball rotation task than the AO group. This result supports the findings of a previous studyRegarding brain activity, the left DLPFC (Ch1) and right PMC (Ch21) of the VMI group were significantly decreased compared to those of the AO group during improvement phase 1. This result supports the findings of previous studiesIn the AO group, the right PMC (Ch21) and left Pa (Ch38) in improvement phase 2 were significantly lower than those in improvement phase 1. A previous study reported that the right DLPFC and left Pa decreased with motor learningOne limitation of this study is that it did not measure mid- to long-term motor performance or brain activity changes during VMI. Second, we did not measure actual motor performance conditions. Future research should include motor performance conditions and investigate the mid- to long-term changes in motor learning. Third, because fNIRS was used, it only measured brain activity in the surface layer of the cerebral cortex. The cerebellum is particularly involved in motor learningIn conclusion, VMI changes motor function and brain activity and promotes the early stages of motor learning in healthy individuals.