Dynamic changes in the cortico-subcortical network during early motor learning

Background: Failure of early motor learning due to damage in any brain area involved in this process may interfere with successful rehabilitation of such patients. Objective: We investigated the changes in activation of the motor network during sequential finger motor learning to delineate the characteristics of the cortico-subcortical network during motor skill learning. Methods: Twenty healthy, right-handed volunteers participated. Subjects were instructed to perform eight blocks of a sequential finger motor task while functional MRI (fMRI) was performed. Results: The participants had an improvement in performance over time from block 1 to block 4, indicating that successful learning had occurred, followed by a plateau from block 5 to the last block. On fMRI, activities of the contralateral primary sensorimotor cortex, the premotor cortex, the supplementary motor area, and the posterior parietal cortex gradually increased from block 1 to block 4 and then decreased from block 5 to the last. In contrast, activity of the ipsilateral cerebellum showed a linear increase spanning the last block with peak activation. The thalamus and basal ganglia showed unilateral or bilateral activities at the unique stage of motor learning. Conclusions: These findings delineated the characteristic plastic changes and different roles of the cortico-subcortical network during the early phase of motor learning and automatization.