Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

We recorded whole-scalp magnetoencephalographic (MEG) signals simultaneously with surface electromyographic (EMG) activity from eight patients with Parkinson's disease after withdrawal and reinstatement of treatment with levodopa. Variations were seen in the coherence between the forearm extensor EMG and the MEG signal originating near or in the hand region of the primary motor cortex. As a group, the parkinsonian patients withdrawn from levodopa showed a reduction in the coherence at 15-30 Hz and 35-60 Hz, and a further three untreated patients had abnormally strong MEG-EMG coherence at 5-12 Hz compared with when medicated or with eight healthy age-matched control subjects. We conclude that the basal ganglia have a specific effect on the temporal organization of motor cortical activity during voluntary tonic contraction. Abnormalities in this aspect of basal ganglia function may directly contribute to bradykinesia and weakness in Parkinson's disease.


Journal article



Publication Date





491 - 500


Adult, Aged, Anterior Horn Cells, Antiparkinson Agents, Basal Ganglia, Biological Clocks, Cortical Synchronization, Efferent Pathways, Electromyography, Female, Humans, Levodopa, Magnetoencephalography, Male, Middle Aged, Motor Cortex, Muscle Contraction, Muscle, Skeletal, Parkinson Disease, Recovery of Function, Treatment Outcome