The smooth pursuit eye movements and fixation ability of children aged 8 to 16 years with Tourette syndrome (TS) were examined.
Although several studies have examined the saccadic ability of patients with TS, there have been only a few studies examining pursuit ability in TS.
Pursuit gain (eye velocity/target velocity) and intrusive saccades during fixation were measured in children with TS-only, TS+attention deficit hyperactivity disorder (ADHD), and TS+ADHD+obsessive compulsive disorder (OCD), and in controls (8 to 16 y). Two pursuit tasks and 1 fixation task were used. In random pursuit 1 (RP1), each step and ramp cycle began from fixation; in random pursuit 2 (RP2), each cycle followed the next. In the fixation task, children were required to maintain fixation on a center dot and ignore distractor stimuli.
All children had significantly higher pursuit gains in RP2 than in RP1 when pursuing a 30 degrees/s moving target. In addition, in RP2, the TS+ADHD+OCD group displayed significantly higher pursuit gains relative to the TS-only, TS+ADHD, and control groups. In the fixation task, the TS+ADHD group exhibited significantly more intrusive saccades than the TS+ADHD+OCD and control groups.
Our findings support an enhanced oculomotor ability in the TS+ADHD+OCD group and the presence of an online gain control mechanism during ongoing pursuit. These findings are discussed in more detail.
*Centre for Vision Research, York University
†Tourette Syndrome Neurodevelopmental Clinic and Toronto Western Research Institute, University of Toronto
‡YDL Institute, Youthdale Treatment Centers, Toronto, Ontario, Canada
Research reported in this article was supported by Natural Sciences and Engineering Research Council Grant 203699, A7664, the Sir Jules Thorn Charitable Trust, the Krembil Foundation, an anonymous donor, and the Canadian Institute of Health Research/Canadian National Institute for the Blind’s E.A. Baker Foundation.
The authors declare no conflicts of interest.
Reprints: Diana J. Tajik-Parvinchi, PhD, Tourette Syndrome Neurodevelopmental Clinic and Toronto Western Research Institute, 399 Bathurst Street, Toronto, Ontario, Canada, M5T 2S8 (e-mail: firstname.lastname@example.org).
Received December 8, 2010
Accepted August 25, 2011