title: Reduced frontal activation during a working memory task in mild cognitive impairment: a non-invasive near-infrared spectroscopy study.
abstract: OBJECTIVE
  Working memory (WM) impairments are considered to be a main feature of mild cognitive impairment (MCI). Functional brain imaging studies have revealed evidence of alterations in the frontal and temporal cortices associated with WM in MCI patients. However, some imaging methods are too expensive for routine clinical use and have a low temporal resolution.
  
  
  METHODS
  Using a newly developed near-infrared spectroscopy (NIRS) system, we studied the spatiotemporal dynamics of oxygenated hemoglobin (oxy-Hb) during a WM task in eight patients with mild cognitive impairment (MCI) and 16 age- and gender-matched healthy controls.
  
  
  RESULTS
  We performed temporal and spatial correlation analyses on each group during their WM tasks. These results consistently demonstrated that, when compared with the healthy controls, the MCI patients exhibited significantly decreased activation in the left frontal, right superior frontal and left temporal lobes. We found evidence of altered frontal and temporal processing during WM tasks in the MCI patients.
  
  
  CONCLUSIONS
  These results confirm the functional deficits in the frontal and temporal cortices and the impairment of WM and cognitive abilities in MCI patients and suggest that fNIRS may be a useful tool for evaluating brain activation in cognitive disorders.
authors.affiliation: State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, China.
authors.forename: Hai-Jing
authors.initials: HJ
authors.lastname: Niu
authors.forename: Xin
authors.initials: X
authors.lastname: Li
authors.forename: Yao-Jing
authors.initials: YJ
authors.lastname: Chen
authors.forename: Chao
authors.initials: C
authors.lastname: Ma
authors.forename: Jun-Ying
authors.initials: JY
authors.lastname: Zhang
authors.forename: Zhan-Jun
authors.initials: ZJ
authors.lastname: Zhang
mesh_terms: D000368:Aged; D060825:Cognitive Dysfunction / Q000175:diagnosis* / Q000378:metabolism*; D015536:Down-Regulation / Q000502:physiology*; D005260:Female; D005625:Frontal Lobe / Q000378:metabolism*; D006801:Humans; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D008875:Middle Aged; D011597:Psychomotor Performance / Q000502:physiology*; D019265:Spectroscopy, Near-Infrared / Q000379:methods*