Subthalamic stimulation evoked cortical responses relate to motor performance in Parkinson's disease

Subthalamic deep brain stimulation is effective in alleviating motor symptoms in Parkinsons disease. Establishing the clinically best stimulation settings often requires time-consuming test sessions and creates a need for biomarkers to optimize this process. While stimulation-evoked cortical responses have been proposed as such a neurophysiological marker, their relationship to motor performance has not yet been studied systematically. For this aim, we recorded finger-tapping movements and cortical responses evoked by different stimulation amplitudes of 22 patients with Parkinsons disease using magnetoencephalography. The motor cortex amplitude was a significant predictor of a higher finger tap frequency and a more regular tapping profile. In addition, subthalamic stimulation evoked responses in the inferior and middle frontal gyrus, and the supplementary motor area. While earlier studies relied on a limited cortical coverage, we reveal a cortical distribution of responses that aligns with the basal ganglia-thalamo-cortical network. Our study sheds light on the relationship between cortical responses evoked by subthalamic stimulation and motor performance based on objective quantitative parameters. Stimulation-evoked responses could guide clinical programming in the future.