The oscillatory activity in the Parkinsonian subthalamic nucleus investigated using the macro-electrodes for deep brain stimulation

Objectives: To investigate the oscillatory activity in the Parkinsonian subthalamic nucleus using the macro-electrodes for deep brain stimulation. Methods: During bilateral deep brain stimulating electrode implantation, spontaneous and evoked field potentials were recorded from the subthalamic nucleus (STN) in two patients with Parkinsonʹs disease (PD) during spontaneous resting tremor, passive manipulation of the wrist, and following electrical stimulation of the contralateral STN. Results: Frequency analysis of the STN field potentials recorded during spontaneous resting tremor showed significant coherence with electromyographic activity in the contralateral arm, suggesting a close involvement of the STN in the generation of resting tremor in PD. The STN responded to passive movement of the contralateral wrist, but not to ipsilateral movement. High frequency (100 Hz) electrical stimulation of the STN induced tremor (4 Hz) in both forearms, and also oscillation of the contralateral STN (4 Hz). In contrast, low frequency (5 Hz) stimulation induced contralateral arrhythmic involuntary movement (3 Hz), but without altering the contralateral STN activity. Conclusions: We propose that the functional connection between the STN and arm muscles is mainly contralateral, but cross talk may occur between bilateral STN via a frequency-dependent pathway.