title: The heterogeneity of aging brain: altered functional connectivity in default mode network in older adults during verbal fluency tests.
abstract: BACKGROUND
  Successful aging (SA) and mild cognitive impairment (MCI) are heterogeneous groups of aging. To explore the heterogeneity, the functional connectivity was studied in these populations.
  
  
  METHODS
  The present study utilized functional connectivity magnetic resonance imaging (fcMRI) to investigate default mode network (DMN) in 8 healthy subjects of SA, 8 subjects of usual aging (UA), and 8 MCI patients during verbal fluency tests (VFTs). Functional connectivity (based seeds) of different groups was analyzed by using statistical test.
  
  
  RESULTS
  Compared with SA and UA groups, MCI subjects exhibited decreased functional connectivity in the DMN regions, including the inferior parietal lobule and left angular gyrus (t = 3.53, P < 0.001). Compared with UA and MCI groups, the SA elderly exhibited increased functional connectivity in the precuneus (t = 3.53, P < 0.001).
  
  
  CONCLUSIONS
  These findings suggested that abnormalities of functional connectivity in DMN might be related with semantic memory impairment in aging. Left angular gyrus and precuneus might be the potential imaging-based biomarker for distinguishing heterogeneous process of elderly.
authors.affiliation: Key Laboratory for Neuroinformation of Ministry of Education, School of Life Science and Technology, University of Electronic Science and Technology of China, North Jianshe Road, Chengdu, Sichuan, China.
authors.forename: Li
authors.initials: L
authors.lastname: Dong
authors.forename: Yuan
authors.initials: Y
authors.lastname: Shen
authors.forename: Xu
authors.initials: X
authors.lastname: Lei
authors.forename: Cheng
authors.initials: C
authors.lastname: Luo
authors.forename: Qing-wei
authors.initials: QW
authors.lastname: Li
authors.forename: Wen-yuan
authors.initials: WY
authors.lastname: Wu
authors.forename: De-zhong
authors.initials: DZ
authors.lastname: Yao
authors.forename: Chun-bo
authors.initials: CB
authors.lastname: Li
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001921:Brain / Q000503:physiopathology*; D060825:Cognitive Dysfunction / Q000503:physiopathology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009483:Neuropsychological Tests