Corticomuscular Coupling During Upper Limb Multijoint Composite Movement: A Multichannel EEG and EMG Study

The upper limb movement control involves the coordinated motion of multiple joints, including the shoulder, elbow, and wrist, and encompasses complex brain–limb neural interactions. This study explored the relationship between the brain and muscles during such tasks from the perspective of corticomuscular coupling. Employing the multivariate global synchronization index, we measured the coupling of multichannel electroencephalogram (EEG) and electromyography (EMG) signals during different stages of a right upper limb multijoint composite motion in healthy subjects. Our findings reveal that significant differences in beta band coupling were observed between different muscles and the brain during the ipsilateral task. Additionally, dynamic forces during coordination tasks exhibited significantly higher global synchronization indices compared to static tasks. Furthermore, the ratio of global synchronization index between the brain and proximal and distal muscle groups is stronger during static tasks than that in dynamic tasks. These findings deepen our understanding of the brain–limb interaction mechanisms during multijoint composite motion and provide opportunities to explore differences in muscle group interactions.