Cueing-Dependent Activity in Bilateral M1 in Parkinson’s Disease

Abstract

We investigated rhythmic force production during two different types of cueing; regular and irregular sequences of tactile stimuli. We expected the corresponding movement-related cortical activity to be most distinguishable in the beta frequency range (13–30 Hz). This accompanying beta activity was expected to show a differential effect of cueing. Twenty Parkinson patients and fifteen age-matched healthy controls performed 3×30 s series of rhythmic movements separated by rest. Each series was performed using (ir-)regular cueing. Using linear beamformers, MEG recordings revealed dominant motor-related activity in bilateral M1s. As expected, at theses sources the Hilbert amplitude of alpha and beta oscillations displayed reduced activity during motor performance. We found a sustained beta rebound during subsequent resting states to a higher level compared to pre-performance. This rebound lasted 5–10 s in both Parkinson patients and controls and its strength depended on cueing type. We also found a likewise sustained effect in the alpha band, where amplitude remained low after movement termination. Although quality of performance largely agreed for patients and controls, dependent on cueing type both the beta rebound and the alpha after-effect differed. The latter discriminated between groups which indicates that Parkinson patients used the same strategy (or attentional load) for mere rhythmic performance (regular cue) or tracking (irregular cue).