title: Interhemispheric resting state functional connectivity abnormalities in unipolar depression and bipolar depression.
abstract: OBJECTIVE
  Depression in the context of bipolar disorder (BD) is often misdiagnosed as unipolar depression (UD), leading to mistreatment and poor clinical outcomes. However, little is known about the similarities and differences in interhemispheric functional connectivity between BD and UD.
  
  
  METHODS
  Patients with bipolar II disorder (n = 36) and UD (n = 32) during a depressive episode as well as 40 healthy controls underwent resting-state functional magnetic resonance imaging. The functional connectivity between any pair of symmetric interhemispheric voxels (i.e., functional homotopy) was measured by voxel-mirrored homotopic connectivity (VMHC).
  
  
  RESULTS
  The three groups showed significant VMHC differences in the posterior cingulate cortex (PCC), fusiform and lingual gyrus, anterior lobe of the cerebellum (CeAL), and posterior lobe of the cerebellum (CePL). In the BD group, the VMHC decreases in the fusiform/lingual gyrus, CeAL, and CePL were shown relative to controls. In the UD group, the VMHC decreases in the PCC, fusiform/lingual gyrus, and CePL were shown relative to controls. No regions of increased VMHC were detected in either patient group. There was no significant difference in the VMHC values in any brain region between the BD group and the UD group.
  
  
  CONCLUSIONS
  Depressive episodes in BD and UD have similar impairments of interhemispheric coordination, which might imply an overlap in the neuropathology of depression.
authors.affiliation: Clinical Experimental Center, First Affiliated Hospital of Jinan University, Guangzhou, China.|Medical Imaging Center, First Affiliated Hospital of Jinan University, Guangzhou, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Psychiatry, First Affiliated Hospital of Jinan University, Guangzhou, China.
authors.forename: Shuming
authors.initials: S
authors.lastname: Zhong
authors.affiliation: Department of Psychiatry, First Affiliated Hospital of Jinan University, Guangzhou, China.
authors.forename: Yanbin
authors.initials: Y
authors.lastname: Jia
authors.affiliation: Medical Imaging Center, First Affiliated Hospital of Jinan University, Guangzhou, China.
authors.forename: Zhifeng
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: Department of Psychiatry, First Affiliated Hospital of Jinan University, Guangzhou, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Wang
authors.affiliation: Department of Psychiatry, First Affiliated Hospital of Jinan University, Guangzhou, China.
authors.forename: Jiyang
authors.initials: J
authors.lastname: Pan
authors.affiliation: Medical Imaging Center, First Affiliated Hospital of Jinan University, Guangzhou, China.
authors.forename: Li
authors.initials: L
authors.lastname: Huang
mesh_terms: D000293:Adolescent; D000328:Adult; D001714:Bipolar Disorder / Q000503:physiopathology*; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D002531:Cerebellum / Q000503:physiopathology; D003863:Depression; D003866:Depressive Disorder / Q000503:physiopathology*; D005260:Female; D059907:Functional Neuroimaging; D006179:Gyrus Cinguli / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000503:physiopathology; D009778:Occipital Lobe / Q000503:physiopathology; D055815:Young Adult
keywords: bipolar disorder; functional magnetic resonance imaging; unipolar depression; voxel‐mirrored homotopic connectivity