Aging suppresses subthalamic neuronal activity in patients with Parkinson’s disease

Age is a primary risk factor for Parkinson’s Disease (PD) however the effects of ageing in the Parkinsonian brain remain poorly understood, particularly for deep brain structures. We investigated intraoperative micro-electrode recordings from the subthalamic nucleus (STN) of PD patients aged between 42 and 76 years. Age was associated with decreased oscillatory beta power and non-oscillatory high-frequency power, independent of PD-related variables. Single unit firing and burst rates were also reduced, whereas coefficient of variation and the structure of burst activity were unchanged. Phase synchronization (debiased phase lag index) between sites was pronounced in the beta band between electrodes in the superficial STN, but was unaffected by age. Our results show that aging was associated with reduced neuronal activity, without changes to its temporal structure. We speculate that the loss of activity in the STN may mediate the relationship between PD and age.