Antisaccade eye movement abnormalities in Tourette syndrome: evidence for cortico-striatal network dysfunction?

Saccadic eye movements are rapid eye movements which act to redirect the ey es from one object of interest to another. Accurately and objectively measu rable, their underlying neuroanatomical mechanisms have been extensively st udied. The antisaccade task allows the study of the frontocortico-striatal network involved in the voluntary control of saccadic eye movements. In thi s task, the subject is instructed to inhibit a reflex eye movement towards a peripheral target light and, instead, to generate a movement in the equal and opposite direction. An error occurs when the subject fails to suppress reflexive saccades towards the target. Significantly high error rates and increased latencies in the antisaccade task have been reported in disorders associated with dysfunction of the frontocortico-striatal network. Increas ed saccadic eye movement latencies and error rates have been reported in To urette syndrome patients (n = 4) who were receiving antipsychotic medicatio n. To investigate this further, we tested the antisaccade task on six male Tourette syndrome patients. The results were compared with 18 age- and sex- matched mentally and physically healthy, medication/alcohol-free controls. Antisaccade latenecies were (mean +/- SD; ms) 751.2 +/- 186.7 for the Toure tte syndrome group and 417 +/- 75.3 for controls, and error rates were 59 /- 14.3 for the Tourette syndrome group and 11.9 +/- 6.4 for controls, repe ctively. These significant results may further support dysfunction of the f rontocortico-striatal network in Tourette syndrome.