Subthalamic Beta Burst Dynamics Differs for Parkinson’s Disease Phenotypes

Parkinson’s Disease (PD) is a neurodegenerative illness associated with dopaminergic loss in the basal ganglia circuit which can lead to heterogeneous motor symptoms such as tremor, rigidity and bradykinesia. The electrophysiological phenomena underlying these symptoms  is not completely understood, which imposes a major challenge for designing customized and more efficient Deep Brain Stimulation (DBS) protocols to match patients’ specificities and needs. Recently, it has been shown that elevated and prolonged beta (13–35 Hz) oscillations (i.e. beta bursts) from the subthalamic nucleus (STN) are associated with motor impairment in PD. Furthermore, motor improvement induced by pharmacological treatment relates to attenuation of intermittent beta activity. This work aims to analyze beta burst dynamics of two phenotypes of PD patients—the tremor dominant (TD) and the postural instability and gait difficulty (PIGD)—to better understand how features of beta oscillations correlate with the motor symptoms in such different PD’s categories. Through a wavelet analysis of 35 LFPs recorded in the sensorimotor portion of the STN from 15 TD and 20 PIGD patients, we show that PIGD patients exhibit longer beta bursts, while TD patients exhibit higher beta burst probability and an inverse significant correlation of burst duration with the rigidity score. These findings may provide critical markers for characterizing the electrophysiological mechanism underlying PD phenotypes and their symptoms, as also contribute to more efficient and customized DBS strategies.