Pathological subthalamic nucleus oscillations in PD: Can they be the cause of bradykinesia and akinesia?

There is growing evidence that Parkinson's disease (PD) is associated with pathological synchronous oscillatory activity in the basal ganglia. These synchronized oscillations primarily occur in the 11–30 Hz range, the so-called beta band. Studies of local field potential activity in the subthalamic nucleus (STN) of PD patients suggest that exaggerated beta band oscillatory activity can disrupt function and, in particular, may contribute to slowness of movement. It has been previously shown that the degree of beta oscillatory activity in the STN of PD patients correlates with the patients' benefit from dopaminergic medications, but not with baseline motor deficits. In a paper that was recently published in Experimental Neurology, [Kuhn A.A., Tsui A., Aziz T., Ray N., Brucke C., Kupsch A., Schneider G.H., Brown P., 2009. Pathological synchronisation in the subthalamic nucleus of patients with Parkinson's disease relates to both bradykinesia and rigidity. Exp. Neurol. 215, 380–387.] the authors further establish that the degree of suppression of beta oscillations in the STN by dopaminergic medications can predict the level of improvement in bradykinesia and rigidity but not tremor. This commentary reviews some of the recent findings on beta oscillatory activity in PD and highlights the possible role of these pathological oscillations in mediating PD symptoms.