Visuomotor Adaptation in Early Stage Modulates Brain Network and Activity in Frontal Regions

The frontal regions are involved in the early stage of motor adaptation. However, the interactions between prefrontal cortex (PFC) and motor cortex (MC) in the regions are still unclear. Therefore, we investigated the relationship between PFC and MC in the early stage of motor adaptation using analyses of brain activity and its effective connectivity (EC). To promote motor adaptation, right-handed participants were trained to perform a visuomotor task with their right hand. Their brain activities before and after training were measured by near-infrared spectroscopy (NIRS) to investigate the brain networks. EC analysis revealed that the brain network between ipsilateral (right) PFC and contralateral (left) MC attenuated after the visuomotor training. The brain activity analysis also showed weaker ipsilateral PFC at the post-test compared to the pre-test. Regarding premotor cortex (PMC)/supplemetary motor area (SMA) in MC located in Brodmann’s area 6 (BA6), each hemisphere changed contrastingly, i.e., the ipsilateral activity weakened, while the activity on the contrateral side strengthened. These results suggest that PFC and MC are synchronized in the early stage of motor learning but work independently through the motor adaptation.