Single-pulse subthalamic deep brain stimulation reduces premotor-motor facilitation in Parkinson's disease

Introduction: Deep brain stimulation improves motor symptoms in Parkinson's disease and changes primary motor cortex excitability, but how subthalamic nucleus stimulation affects premotor-motor cortical connectivity remains unclear. Methods: We investigated 10 Parkinson patients in whom single subthalamic nucleus stimulation was time-locked to transcranial magnetic dual-coil, paired-pulse stimulation of the dorsal premotor and primary motor cortex. Premotor-motor interaction with deep brain stimulation switched off was compared to 10 controls. Results: Parkinson patients showed abnormally facilitated premotor-motor interaction with deep brain stimulation switched off compared to controls. This abnormal premotor-motor facilitation was abolished during subthalamic nucleus stimulation at 3 Hz. Conclusions: In Parkinson's disease, aberrant signals from the basal ganglia leading to a loss of physiological premotor-motor inhibition can be normalized by subthalamic deep brain stimulation. This effect is likely mediated by activation of subthalamic-pallidal-thalamic projection to the premotor cortex.