title: Dysfunctional cortical connectivity during the auditory oddball task in patients with schizophrenia.
abstract: BACKGROUND
  We studied the imaginary coherence (IC) of gamma frequency oscillations between brain regions of male schizophrenia patients during an auditory oddball task using magnetoencephalography (MEG) and electroencephalography (EEG).
  
  
  METHODS
  Subjects were 10 right-handed male schizophrenia patients, evaluated by the positive and negative symptom scale (PANSS), and 10 healthy controls. Functional connectivity during the auditory oddball task was reconstructed in low (30-50 Hz) and high (50-100 Hz) gamma bands, and represented by imaginary coherence (IC) based on significant oscillatory power changes. We calculated correlations between PANSS scores and IC.
  
  
  RESULTS
  In the high gamma band, IC between left occipital and right prefrontal lobe areas during the time window 750-1000 ms from stimulus onset showed negative correlations with total negative scores, total positive scores, the sum of positive and negative scores in PANSS, conceptual disorganization, and social avoidance scores. In the low gamma band, IC between the same areas from 250-500 ms also showed a negative correlation with the conceptual disorganization score. In the same time window, IC between left occipital and right frontoparietal lobe areas in the low gamma band showed a positive correlation with hallucinatory behavior; IC between right temporal pole and left prefrontal lobe areas showed a positive correlation with delusion scores, although these ICs were decreased relative to controls.
  
  
  CONCLUSIONS
  Functional disconnection of high and low gamma bands in auditory oddball task may play an important role in the auditory processing in schizophrenia patients.
authors.affiliation: Fujimoto Hayasuzu Hospital, Yokakai Association, Miyazaki, Japan.
authors.forename: Toshiro
authors.initials: T
authors.lastname: Fujimoto
authors.forename: Eiichi
authors.initials: E
authors.lastname: Okumura
authors.forename: Kouzou
authors.initials: K
authors.lastname: Takeuchi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kodabashi
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Otsubo
authors.forename: Katsumi
authors.initials: K
authors.lastname: Nakamura
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Kamiya
authors.forename: Yuji
authors.initials: Y
authors.lastname: Higashi
authors.forename: Tadahiko
authors.initials: T
authors.lastname: Yuji
authors.forename: Kenichi
authors.initials: K
authors.lastname: Honda
authors.forename: Susumu
authors.initials: S
authors.lastname: Shimooki
authors.forename: Toshiyo
authors.initials: T
authors.lastname: Tamura
keywords: Magnetoencephalography; P300.; PANSS; functional connectivity; gamma band; schizophrenia