title: Difference in binocular rivalry rate between patients with bipolar I and bipolar II disorders.
abstract: OBJECTIVE
  When dissimilar figures are presented to each eye individually, perception alternates spontaneously between each monocular view. This phenomenon, known as binocular rivalry, has been used as a powerful tool to investigate conscious visual awareness. Of clinical relevance, Pettigrew and Miller (Proc Biol Sci 1998; 265: 2141-2148) found slow perceptual alternation rates in patients with bipolar I disorder (BD-I). For a better understanding of differences between BD-I and bipolar II disorder (BD-II), we examined whether perceptual alternation rates of binocular rivalry differ between the two subtypes of bipolar disorder.
  
  
  METHODS
  The subjects comprised 25 healthy controls, 11 patients with BD-I, and 17 patients with BD-II. They underwent binocular rivalry examination. One-way analysis of variance was conducted to determine differences in the phase duration of binocular rivalry between the control, BD-I, and BD-II groups.
  
  
  RESULTS
  Significant differences were observed in the mean phase duration of binocular rivalry between the groups. Although the medication administered did not differ significantly between the BD-I and BD-II patients, the phase duration was significantly longer among the BD-I patients than the BD-II patients and controls, whereas no significant difference was observed in the phase duration between the BD-II patients and controls.
  
  
  CONCLUSIONS
  The present results reveal a significant difference in the mean phase duration of binocular rivalry between subjects with BD-I and those with BD-II, suggesting the presence of some neurobiological difference between these two subtypes of bipolar disorder.
authors.affiliation: Department of Psychiatry, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-8513, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Nagamine
authors.forename: Aihide
authors.initials: A
authors.lastname: Yoshino
authors.forename: Masaki
authors.initials: M
authors.lastname: Miyazaki
authors.forename: Yoshitomo
authors.initials: Y
authors.lastname: Takahashi
authors.forename: Soichiro
authors.initials: S
authors.lastname: Nomura
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001714:Bipolar Disorder / Q000145:classification* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010775:Photic Stimulation / Q000379:methods; D015357:Vision Disparity / Q000502:physiology*; D015348:Vision, Binocular / Q000502:physiology*