The acute brain response to levodopa heralds dyskinesias in Parkinson disease.

In Parkinson disease (PD), long-term treatment with the dopamine precursor levodopa gradually induces involuntary "dyskinesia" movements. The neural mechanisms underlying the emergence of levodopa-induced dyskinesias in vivo are still poorly understood. Here, we applied functional magnetic resonance imaging (fMRI) to map the emergence of peak-of-dose dyskinesias in patients with PD.