Tourette's Syndrome (TS) is a poorly understood neurological disorder characterized by multiple motor and phonic tics and associated behavioral disturbances. While TS is clearly a disorder of motor function, the nature of the tics and the associated cognitive and behavioral features suggest that the pathogenesis extends beyond the motor domain. The motivational tension that commonly precedes motor and vocal tics and the sense of relief that follows their expression, as well as the irritability, impulsivity, depression or self-injurious behavior that may characterize more complex cases, all tend to suggest that brain regions associated with motivation or affect may also be involved. The generation of symptoms in TS might in fact reflect an abnormality of brain systems that effect neural transmission from the limbic