Event-related functional magnetic resonance imaging in Parkinson's diseasebefore and after levodopa

Event-related functional MRI (fMRI) was used to study blood oxygen level de pendent cortical signal changes associated with volitional limb movements o ff and on levodopa in Parkinson's disease. Eight patients with early stage akinetic Parkinson's disease and eight healthy volunteers underwent three f unctional imaging runs thigh speed echo planar imaging with 600 scans/run) while performing paced single joystick movements in a freely chosen directi on every 7-15 s, The non-magnetic joystick was linked to a monitoring syste m for on-line registration of performance parameters along with timing of t he pacing tones and fMRI-scan acquisition parameters. This allowed correlat ion of movement onset, i.e. event-onset, to scanning time. We repeated the scanning procedure in the Parkinson's disease patients when akinesia improv ed 30 min after oral levodopa, Compared with the control group, patients bo th off and on levodopa showed movement-related impaired activation in the r ostral supplementary motor area and increased activation in primary motor c ortex (M1) and the lateral premotor cortex bilaterally. Levodopa led to a r elative normalization of the impaired activation in the mesial premotor cor tex and decreased signal levels in M1, lateral premotor and superior pariet al cortex. We conclude that levodopa improves impaired motor initiation in the supplementary motor area and decreases hyperfunction of lateral premoto r and M1 associated with Parkinson's disease during simple volitional movem ents.