title: Interhemispheric functional disconnection because of abnormal corpus callosum integrity in bipolar disorder type II.
abstract: BACKGROUND
  A significantly lower fractional anisotropy (FA) value has been shown in anterior parts of the corpus callosum in patients with bipolar disorder.
  
  
  OBJECTIVE
  We investigated the association between abnormal corpus callosum integrity and interhemispheric functional connectivity (IFC) in patients with bipolar disorder.
  
  
  METHODS
  We examined the association between FA values in the corpus callosum (CC-FA) and the IFC between homotopic regions in the anterior cortical structures of bipolar disorder (n=16) and major depressive disorder (n=22) patients with depressed or euthymic states.
  
  
  RESULTS
  We found a positive correlation between the CC-FA and IFC values between homotopic regions of the ventral prefrontal cortex and insula cortex, and significantly lower IFC between these regions in bipolar disorder patients.
  
  
  CONCLUSIONS
  The abnormal corpus callosum integrity in bipolar disorder patients is relevant to the IFC between homotopic regions, possibly disturbing the exchange of emotional information between the cerebral hemispheres resulting in emotional dysregulation.
  
  
  BACKGROUND
  None.
  © The Royal College of Psychiatrists 2016. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) license.
authors.affiliation: , MD, PhD, Department of Psychiatry, Nara Medical University, Kashihara, Japan; Neurology, National Cerebral and Cardiovascular Center, Suita, Japan.
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Yasuno
authors.affiliation: , MD, PhD, Department of Psychiatry, Osaka University Health Care Center, Toyonaka, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kudo
authors.affiliation: , MD, Department of Psychiatry, Nara Medical University, Kashihara, Japan.
authors.forename: Kiwamu
authors.initials: K
authors.lastname: Matsuoka
authors.affiliation: , MS, Department of Investigative Radiology, National Cerebral and Cardiovascular Center, Suita, Japan.
authors.forename: Akihide
authors.initials: A
authors.lastname: Yamamoto
authors.affiliation: , MD, Department of Psychiatry, Nara Medical University, Kashihara, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Takahashi
authors.affiliation: , MD, PhD, Integrative Stroke Imaging Center, National Cerebral and Cardiovascular Center, Suita, Japan.
authors.forename: Jyoji
authors.initials: J
authors.lastname: Nakagawara
authors.affiliation: , MD, PhD, National Cerebral and Cardiovascular Center, Suita, Japan.
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Nagatsuka
authors.affiliation: , PhD, National Cerebral and Cardiovascular Center, Suita, Japan.
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Iida
authors.affiliation: , MD, PhD, Department of Psychiatry, Nara Medical University, Kashihara, Japan.
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Kishimoto