Task-related EEG-EEG coherence depends on dopaminergic activity in Parkinson's disease.
Cassidy M., Brown P.
We investigated whether functional coupling between different cortical areas is impaired in Parkinson's disease, using corticocortical coherence as a surrogate measure of coupling. We recorded scalp EEG from different sites in seven parkinsonian patients while they tracked a visual target using their wrist, or copied the same movement from memory. Differences in EEG-EEG coherence between the tracking and copying tasks and their respective controls, visual tracking alone and fixation of a stationary target, were determined on and off levodopa. After levodopa we found extensive task-specific and broad band cortico-cortical coherence. Off levodopa cortico-cortical coherence was much reduced. Ascending dopaminergic projections from the ventral mesencephalon may therefore be important in determining the pattern and extent of corticocortical coupling during executive tasks.