 Clinical observations suggest that in TS there is abnormal function in the brains motor system that can be modified by manipulating dopamine. My colleagues and I have hypothesized that nonmotor brain systems may also show dopamine-sensitive functional abnormalities. Recently we tested this hypothesis using functional magnetic resonance imaging fMRI. A cognitive task involving working memory WM produced excessive activation of several brain regions in TS subjects compared to controls, but this excessive activation normalized after administering the dopamine precursor levodopa Hershey et al, 2004. 