Bradykinesia and impairment of EEG desynchronization in Parkinson's disease

It has been suggested that the basal ganglia control the release of cortica l elements from low-frequency rhythmic idling activity during voluntary mov ement.(1) This hypothesis was tested by recording the local idling rhythms of the motor cortex, the alpha and beta rhythms, in 12 untreated and treate d patients with Parkinson's disease as they moved a wrist. Recordings were made after overnight withdrawal of medication and again 1 hr after levodopa . The treatment-related attenuation of the alpha and beta rhythms picked up over the cortical motor areas contralateral to the active arm correlated w ith the improvement in size and speed of movement effected by levodopa. The distribution and degree of attenuation depended on the complexity of the t ask. These results demonstrate for the first time a specific effect of levo dopa on the organization of motor cortical activity in the frequency domain , an effect that correlates with improvements in bradykinesia.