Adaptive behavior requires procedural motor learning, i.e. the acquisition of motor skills. Procedural learning is particularly critical in the rehabilitation of chronic motor deficits after stroke. A potent modulator of motor function and learning is found in the endogenous dopaminergic system. The investigator's own work could demonstrate that formation of an elementary motor memory, which constitutes the first step in acquiring more complex motor skills, can be enhanced in both healthy subjects and chronic stroke patients by pre-medication with levodopa. The aim of the present proposal is to: