Dopamine-dependent high-frequency oscillatory activity in thalamus and subthalamic nucleus of patients with Parkinson's disease.

In recent years there has been great interest in oscillatory activity in the brain and in the role of pathological oscillations in the basal ganglia in mediating some of the symptoms of Parkinson's disease (PD). In this study, thalamic and subthalamic nucleus local field potentials were intraoperatively recorded from pairs of closely separated microelectrodes in six PD patients ON and OFF dopaminergic medication. Using correlation and coherence analyses, we found high-frequency oscillatory activity in the 110-170 Hz band in thalamus in patients OFF dopamine. These oscillations were significantly reduced after administration of dopamine-replacement therapy. In contrast, activity in the lower frequencies (the theta and beta ranges) was increased. However, in subthalamic nucleus, we observed an increase in high-frequency oscillatory activity (150-200 Hz), and a reduction of the activity in the low-frequency range after levodopa administration. These findings confirm and extend earlier findings suggesting that in PD there are marked changes in basal ganglia oscillatory activity and that these can be reversed after dopaminergic therapy.