MOVE

Simultaneous magnetoencephalography and subthalamic local field potential recordings in Parkinson patients

Insight into how brain structures interact is critical for understanding the principles of brain function and may lead to better diagnosis and therapy. To study interactions between the cortex and deep brain structures (basal ganglia and the thalamus) we recorded, simultaneously, local field potentials (LFPs) from deep brain stimulation (DBS) electrodes and magnetoencephalographic (MEG) signals from the cerebral cortex (CTF 275 channel system) from Parkinson’s disease (PD) patients with bilateral DBS electrodes in the subthalamic nucleus (STN). We found that beamforming can effectively suppress high-amplitude artefacts in the MEG of these patients that pose a challenge to conventional analysis methods. We, therefore, used beamforming to localize cortical areas whose activity is modulated by movement and obtain artefact-free source recordings from these areas. Time-frequency analysis of the source data around finger movements revealed power dynamics consistent with previously published findings including event-related desynchronization followed by synchronization in the alpha and beta bands and high gamma activity around the time of movement in both motor cortex (M1) and STN. We used a novel analysis method – dynamic causal modelling for induced responses to assess the coupling between M1 and STN and its modification by dopamine replacement therapy and by the movement complexity.