Cortico-Motor Coherence during Deep Brain Stimulation for Parkinson's Disease

Parkinsonian motor symptoms can be relieved by deep brain stimulation on the subthalamic nucleus. However, the underlying neurophysiology has not been fully understood. In a magnetoencephalography study by Park et al., the authors measured the cortico-muscular coherence from three Parkinson's disease subjects with resting tremor. The coherence was measured while the deep brain stimulation was both on and off. Meanwhile, previous studies have shown that healthy humans performing isometric contractions show increased cortico-muscular coherence in the beta-band. Hypothesizing that this can be a measure of symptomatic improvement in motor performance after deep brain stimulation on the subthalamic nucleus, the authors compared the beta-band cortico-muscular coherence during the two states of stimulators. The results showed that the cortico-muscular coherence was elevated for the tremorous hand when the stimulator was on. The authors suggest that the result indicates that deep brain stimulation resulted in better cortico-muscular coordination.