A Randomized, Double-blind, Placebo Controlled, Two-way Cross-over Study to Explore the Effects of 7 Days of Dosing With SYN115 20 mg p.o. BID or 60 mg p.o. BID on Clinical and fMRI Response to Intravenous Levodopa in Patients With Mild to Moderate Parkinson's Disease A Randomized, Double-blind, Placebo Controlled, Two-way Cross-over Study to Explore the Effects of 7 ...