Effect of perceptual learning on motor skills of hands: a functional magnetic resonance imaging study.

Our aim was to clarify the mechanism by which perceptual learning improves motor skills of hands. We included 18 healthy volunteers (age 21.3 ± 0.3 years, mean ± standard deviation) in the study with a crossover design. The subjects were randomly classified into 3 groups, and they performed a 2-ball quick rotation task with a hand. The role of perceptual learning in improving the ability to discern the length of a wooden stick held between the left thumb and index finger was studied between the first and second sessions of the task in group A, and between the second and third sessions in groups B and C with a period of rest interval between the first and second sessions. Functional magnetic resonance imaging (fMRI) was performed for each group during the perceptual learning session. The effect of intervention, in the form of perceptual learning, on the task performance was significantly greater than that of non-intervention in all subjects (p = 0.022). Among all the activated brain areas, the bilateral prefrontal cortices, right premotor area, right supplementary motor area, right primary sensory area, right primary motor area, right inferior parietal lobe, right thalamus, and left cerebellar posterior lobe showed positive correlations between the respective contrasts from the single-subject analysis and the behavioral data before and after the interventions (p < 0.001). This result indicates a pivotal role of the frontoparietal or frontocerebellar circuits in sensorimotor integration; a specific approach that activates these circuits should be developed for clinical rehabilitation of patients.