Klinische Neurophysiologie 2011; 42 - P234
DOI: 10.1055/s-0031-1272681

Subthalamic γ Activity Depends on Movement Amplitude and Velocity

A. Bock 1, J. Huebl 1, S. Siegert 1, V. Litvak 1, G.H. Schneider 1, A. Kupsch 1, A.A. Kühn 1
  • 1Berlin; London, UK

Introduction: Event-related synchronization (ERS) in gamma band activity (60–80Hz) recorded from the subthalamic nucleus (STN) contralateral to the moved hand has been shown in Parkinson's disease (PD) patients. Here, we correlate the degree of gamma band ERS to parameters of motor performance such as speed and movement amplitude, and its change with dopaminergic medication.

Methods: In 16 patients (4 females) undergoing deep brain stimulation (DBS) for severe PD, subthalamic local field potentials of adjacent bipolar contact pairs of each DBS electrode were recorded, while patients performed forearm pronation movements of three different angles. Patients were recorded after overnight withdrawal from L-DOPA medication (OFF) and 30 minutes after intake of 200mg of L-DOPA (ON) in a randomized order. Spectral analysis was performed using the multitaper estimation method to compute mean percentage power changes during hand movements relative to baseline. Signals were averaged around movement onset as well as maximum angular velocity. Differences in spectral power changes were assessed between movement conditions and dopaminergic state.

Results: We found a significant increase in gamma band ERS (52–85Hz) ON compared to OFF medication contralateral to the moved hand. Moreover, a stepwise increase of gamma band ERS with larger movement amplitudes and greater velocity was found around movement onset in the contralateral STN being more pronounced in the ON state. The relative increase in movement velocity ON versus OFF medication correlated with the relative increase in gamma band ERS (Kendall's tau=0.3276; p=0.002).

Bilaterally recorded beta band activity (13–30Hz) was significantly more suppressed during movements ON compared to OFF medication but did not show a correlation with movement amplitude nor velocity.

Conclusions: STN gamma band activity is modulated by dopaminergic treatment and correlates with movement amplitude and velocity suggesting that it may support motor performance in PD patients.