title: Preattentive dysfunction in bipolar disorder: a MEG study using auditory mismatch negativity.
abstract: BACKGROUND
  Neuropsychological studies have demonstrated that cognitive dysfunction represents pathophysiological mechanisms underlying bipolar disorder. However, information processing deficits in bipolar disorder have not often been examined electrophysiologically. Here, we examined preattentive processing and sensory information processing using mismatch field (MMNm) and P1m components, respectively, using magnetoencephalography.
  
  
  METHODS
  Ten patients with bipolar disorder and 20 healthy volunteers participated in the study. The participants were presented with auditory stimuli sequences comprising standard and deviant stimuli. MMNm was elicited in response to changes in duration and frequency of pure-tone stimuli and a vowel across-category change.
  
  
  RESULTS
  The magnetic global field power of MMNm in the right hemisphere under the pure-tone condition was significantly delayed in patients with bipolar disorder compared to healthy volunteers, and that of P1m did not differ between the two groups. The MMNm dipole in the left hemisphere was located inferior in patients with bipolar disorder than in healthy volunteers. This finding did not correlate with clinical symptoms.
  
  
  CONCLUSIONS
  Information processing at the preattentive level is impaired in patients with bipolar disorder irrespective of clinical symptoms, and this dysfunction is not due to sensory level dysfunction. The quality of preattentive information processing impairment is different between patients with bipolar disorder and patients with major depressive disorder, as shown by the MMNm latency and power differences.
authors.affiliation: Department of Psychiatry and Human Behavior, Gunma University Graduate School of Medicine, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Takei
authors.forename: Sumie
authors.initials: S
authors.lastname: Kumano
authors.forename: Yoko
authors.initials: Y
authors.lastname: Maki
authors.forename: Suguru
authors.initials: S
authors.lastname: Hattori
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kawakubo
authors.forename: Kiyoto
authors.initials: K
authors.lastname: Kasai
authors.forename: Masato
authors.initials: M
authors.lastname: Fukuda
authors.forename: Masahiko
authors.initials: M
authors.lastname: Mikuni
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D000704:Analysis of Variance; D001288:Attention / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology; D001714:Bipolar Disorder / Q000503:physiopathology*; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D014796:Visual Perception / Q000502:physiology