title: Resting-state functional connectivity in major depression: abnormally increased contributions from subgenual cingulate cortex and thalamus.
abstract: BACKGROUND
  Positron emission tomography (PET) studies of major depression have revealed resting-state abnormalities in the prefrontal and cingulate cortices. Recently, fMRI has been adapted to examine connectivity within a specific resting-state neural network--the default-mode network--that includes medial prefrontal and anterior cingulate cortices. The goal of this study was to examine resting-state, default-mode network functional connectivity in subjects with major depression and in healthy controls.
  
  
  METHODS
  Twenty-eight subjects with major depression and 20 healthy controls underwent 5-min fMRI scans while resting quietly. Independent component analysis was used to isolate the default-mode network in each subject. Group maps of the default-mode network were compared. A within-group analysis was performed in the depressed group to explore effects of depression refractoriness on functional connectivity.
  
  
  RESULTS
  Resting-state subgenual cingulate and thalamic functional connectivity with the default-mode network were significantly greater in the depressed subjects. Within the depressed group, the length of the current depressive episode correlated positively with functional connectivity in the subgenual cingulate.
  
  
  CONCLUSIONS
  This is the first study to explore default-mode functional connectivity in major depression. The findings provide cross-modality confirmation of PET studies demonstrating increased thalamic and subgenual cingulate activity in major depression. Further, the within-subject connectivity analysis employed here brings these previously isolated regions of hypermetabolism into the context of a disordered neural network. The correlation between refractoriness and subgenual cingulate functional connectivity within the network suggests that a quantitative, resting-state fMRI measure could be used to guide therapy in individual subjects.
authors.affiliation: Department of Neurology and Neurological Sciences, Stanford University Medical Center, Stanford, California 94305-5235, USA. greicius@stanford.edu
authors.forename: Michael D
authors.initials: MD
authors.lastname: Greicius
authors.forename: Benjamin H
authors.initials: BH
authors.lastname: Flores
authors.forename: Vinod
authors.initials: V
authors.lastname: Menon
authors.forename: Gary H
authors.initials: GH
authors.lastname: Glover
authors.forename: Hugh B
authors.initials: HB
authors.lastname: Solvason
authors.forename: Heather
authors.initials: H
authors.lastname: Kenna
authors.forename: Allan L
authors.initials: AL
authors.lastname: Reiss
authors.forename: Alan F
authors.initials: AF
authors.lastname: Schatzberg
mesh_terms: D000328:Adult; D001931:Brain Mapping; D016022:Case-Control Studies; D003865:Major Depressive Disorder / Q000473:pathology* / Q000503:physiopathology*; D005260:Female; D006179:Gyrus Cinguli / Q000098:blood supply*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging; D008297:Male; D009068:Movement / Q000502:physiology; D010100:Oxygen / Q000097:blood; D012146:Rest / Q000502:physiology*; D013223:Statistics as Topic; D013788:Thalamus / Q000098:blood supply*
chemical_list: D010100:Oxygen