title: Impaired smooth pursuit in schizophrenia results from prediction impairment only.
abstract: BACKGROUND
  Oculomotor abnormality is one of the endophenotypes in schizophrenia. The predictive component of smooth pursuit can be studied by comparing the gain, i.e., the ratio of smooth eye position to target position, during predictable (pure sinusoidal) and unpredictable (pseudorandom) target motions. The aim of this experiment was to study predictive and nonpredictive components of smooth pursuit in two groups of schizophrenia patients compared with control subjects.
  
  
  METHODS
  Fifty-one schizophrenia patients (40 nondeficit and 11 deficit) and 21 control subjects were studied. During a predictable task, subjects were asked to track a sinusoidal target (.4 Hz). For the unpredictable task, the pseudorandom target motion consisted of five superimposed sinusoidal waveforms (.1, .2, .4, .6, and .8 Hz). The smooth eye position (eye position without saccades), gain, and phase were calculated for each frequency in each participant and for both tasks.
  
  
  RESULTS
  The mean sinusoidal smooth eye position gain was significantly lower in patients than in control subjects with no significant difference between deficit and nondeficit patients. During the pseudorandom task, all groups had a similar gain at .4 Hz.
  
  
  CONCLUSIONS
  Our study reveals that patients have a normal nonpredictive component of smooth pursuit, regardless of their level of negative symptoms. In contrast, the predictive mechanisms involved in eye pursuit were impaired in schizophrenia patients. These results indicate that poor pursuit performance during smooth pursuit is primarily a consequence of a predictive problem and is not related to the ability to generate an accurate pursuit maintenance response.
authors.affiliation: Rouen University Hospital-Charles Nicolle and Le Rouvray Hospital, Rouen School of Medicine, Rouen, France. tatomdjap2000@yahoo.fr
authors.forename: Irene
authors.initials: I
authors.lastname: Nkam
authors.forename: Marie-Laure
authors.initials: ML
authors.lastname: Bocca
authors.forename: Pierre
authors.initials: P
authors.lastname: Denise
authors.forename: Xavier
authors.initials: X
authors.lastname: Paoletti
authors.forename: Sonia
authors.initials: S
authors.lastname: Dollfus
authors.forename: Daniel
authors.initials: D
authors.lastname: Levillain
authors.forename: Florence
authors.initials: F
authors.lastname: Thibaut
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D009039:Motion Perception / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D011698:Pursuit, Smooth / Q000502:physiology*; D012559:Schizophrenia / Q000503:physiopathology*