title: Smooth pursuit and fixation ability in children with Tourette syndrome.
abstract: OBJECTIVE
  The smooth pursuit eye movements and fixation ability of children aged 8 to 16 years with Tourette syndrome (TS) were examined.
  
  
  BACKGROUND
  Although several studies have examined the saccadic ability of patients with TS, there have been only a few studies examining pursuit ability in TS.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors: Centre for Vision Research, York University, Toronto, Ontario, Canada. dianapar@yorku.ca
authors: Diana J
authors: DJ
authors: Tajik-Parvinchi
authors: Paul
authors: P
authors: Sandor
mesh_terms: D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000150:complications / Q000503:physiopathology; D016022:Case-Control Studies; D002648:Child; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology*; D006801:Humans; D008297:Male; D009771:Obsessive-Compulsive Disorder / Q000150:complications / Q000503:physiopathology; D011698:Pursuit, Smooth / Q000502:physiology*; D005879:Tourette Syndrome / Q000150:complications / Q000503:physiopathology*