Decoupling neuronal oscillations during subthalamic nucleus stimulation in the parkinsonian primate.

Subthalamic nucleus (STN) stimulation is a popular treatment for Parkinson's disease; however, its effect on neuronal activity is unclear. We performed simultaneous multi-electrode recordings in the STN and its targets, the globus pallidus internus (GPi) and externus (GPe) in the parkinsonian non-human primate during high frequency STN macro-stimulation. Our results indicate that in the parkinsonian state the abnormal neuronal oscillatory activity in the 10-15 Hz range is coherent within and between nuclei. We further show that STN macro-stimulation results in a reduction of oscillatory activity in the globus pallidus. In addition, a functional decoupling of the STN from its pallidal targets is evidenced by the reduced STN-GPi coherence, that effectively removes the STN synchronous oscillatory drive of basal ganglia output. This decoupling results in reduced coherence between neurons within the GPi which resume an independent neuronal activity pattern. This decorrelation of the basal ganglia output may result in a reduction of the fluctuations of the basal ganglia inhibitory control over thalamic neurons which may potentially contribute to the beneficial effects of deep brain high-frequency stimulation.