Cortico-muscular coherence increases with tremor improvement after deep brain stimulation in Parkinson's disease.

Deep brain stimulation on the subthalamic nucleus has been used to relieve Parkinsonian motor symptoms. However, the underlying physiological mechanism has not been fully understood. Beta-band cortico-muscular coherence increases when healthy humans perform isometric contraction. We hypothesized that this might be a measure of symptomatic improvement in motor performance after subthalamic nucleus deep brain stimulation. Here, we measured the beta-band cortico-muscular coherence with magnetoencephalography from three Parkinson's disease patients. We then compared the coherence values for stimulator on-state and off-state. We found that when the stimulator is on, the beta cortico-muscular coherence elevates significantly for the tremorous hand compared with that when the stimulator is off. This suggests that deep brain stimulation resulted in better cortico-muscular coordination.