Behavioral laterality in individuals with Gilles de la Tourette's syndrome and basal ganglia alterations: a preliminary report.

This study aims to investigate whether abnormalities in structural basal ganglia asymmetries in Tourette's syndrome (GTS) have functional significance. Eleven adult GTS patients and 11 normal controls who had participated in the previous MRI study where GTS patients lacked the normal left-greater-than-right (L > R) lenticular asymmetry were re-recruited. They were administered a battery of lateralizing neuropsychological tasks believed to require intact basal ganglia function. GTS subjects lacked normal functional asymmetries on these measures, as predicted. The neuropsychological measures also accounted for a significant portion of the variance in the severity of tic symptoms. These findings suggest that GTS subjects who lack normal basal ganglia structural asymmetries also lack normal functional asymmetries on related neuropsychological measures.