High beta activity in the subthalamic nucleus and freezing of gait in Parkinson's disease

Objective: Oscillatory activity in the beta band is increased in the subthalamic nucleus (STN) of Parkinson's disease (PD) patients. Rigidity and bradykinesia are associated with the low-beta component (13-20 Hz) but the neurophysiological correlate of freezing of gait in PD has not been ascertained. Methods: We evaluated the power and coherence of the low- and high-beta bands in the STN and cortex (EEG) of PD patients with (p-FOG) (n = 14) or without freezing of gait (n-FOG) (n = 8) in whom electrodes for chronic stimulation in the STN had been implanted for treatment with deep brain stimulation. Results: p-FOG patients showed higher power in the high-beta band (F = 11.6, p = 0.002) that was significantly reduced after L-dopa administration along with suppression of FOG (F = 4.6, p = 0.042). High-beta cortico-STN coherence was maximal for midline cortical EEG electrodes, whereas the low-beta band was maximal for lateral electrodes (chi(2) = 20.60, p < 0.0001). Conclusions: The association between freezing of gait, high-beta STN oscillations and cortico-STN coherence suggests that this oscillatory activity might interfere in the frontal cortex-basal ganglia networks, thereby participating in the pathophysiology of FOG in PD. (c) 2013 Elsevier Inc. All rights reserved.