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

- Patients with FOG (p-FOG) show increased high beta activity in OFF motor state.
- p-FOG patients without FOG in ON motor state had a decrease in high beta at rest.
- The STN high beta band showed maximal coherence with the SMA EEG recordings.

ObjectiveOscillatory 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.MethodsWe 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.Resultsp-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 (χ2 = 20.60, p < 0.0001).ConclusionsThe 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.