Inhibition of expected movements in Tourette's Syndrome

Tourette's Syndrome (TS) is a basal ganglia (BG) disorder characterized by involuntary motor and vocal tics, impairment of voluntary motor function, and attentional dysfunctions. This experiment aimed to investigate motor reprogramming and inhibitory control in adult TS patients. Ten TS patients and 10 age- and sex-matched controls performed sequences of movements in response to the illumination of LED lights, and were required to interrupt a predictable, reciprocating sequence of leftward and rightward movements in order to move to an unpredictable target that occurred either in the direction opposite to that expected, or in the opposite direction and at twice the expected distance. Results showed that TS patients were no slower than controls in reprogramming the direction and distance of movements, thus showing no overall deficits in inhibitory control. Of interest, however, was a directional asymmetry (right bias) in movement preparation time in TS patients. Patients with TS may have a superiority in allocating attentional resources toward the right side, contralateral to the implicated reduced BG volume in this disorder. These findings extend earlier work reporting anomalous BG lateralization in TS.