title: Structural Connectivity Changes Underlying Altered Working Memory Networks in Mild Cognitive Impairment: A Three-Way Image Fusion Analysis.
abstract: OBJECTIVE
  Working memory impairment is among the earliest signs of cognitive decline in Alzheimer's disease (AD) and mild cognitive impairment (MCI). We aimed to study the functional and structural substrate of working memory impairment in early AD dementia and MCI.
  
  
  METHODS
  We studied a group of 12 MCI and AD subjects compared to 12 age- and gender-matched healthy elderly controls using diffusion tensor imaging (DTI), and functional magnetic resonance imaging (fMRI) during a 2-back versus 1-back letter recognition task. We performed a three-way image fusion analysis with joint independent component analysis of cortical activation during working memory, and DTI derived measures of fractional anisotropy (FA) and the mode of anisotropy.
  
  
  RESULTS
  We found significant hypoactivation in posterior brain areas and relative hyperactivation in anterior brain areas during working memory in AD/MCI subjects compared to controls. Corresponding independent components from DTI data revealed reduced FA and reduced mode of anisotropy in intracortical projecting fiber tracts with posterior predominance and increased FA and increased mode along the corticospinal tract in AD/MCI compared to controls.
  
  
  CONCLUSIONS
  Our findings suggest that impairments of structural fiber tract integrity accompany breakdown of posterior and relatively preserved anterior cortical activation during working memory performance in MCI/AD subjects.
authors.affiliation: Department of Psychosomatic Medicine, University Medicine Rostock, Rostock, Germany.|DZNE, German Center for Neurodegenerative Diseases, Rostock, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Teipel
authors.affiliation: Department of Psychosomatic Medicine, University Medicine Rostock, Rostock, Germany.|DZNE, German Center for Neurodegenerative Diseases, Rostock, Germany.
authors.forename: Inga
authors.initials: I
authors.lastname: Ehlers
authors.affiliation: Department of Psychosomatic Medicine, University Medicine Rostock, Rostock, Germany.|DZNE, German Center for Neurodegenerative Diseases, Rostock, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Erbe
authors.affiliation: Department of Medical Genetics, University Medicine Rostock, Rostock, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Holzmann
authors.affiliation: Department of Psychosomatic Medicine, University Medicine Rostock, Rostock, Germany.|DZNE, German Center for Neurodegenerative Diseases, Rostock, Germany.
authors.forename: Esther
authors.initials: E
authors.lastname: Lau
authors.affiliation: Department of Radiology, University Medicine Rostock, Rostock, Germany.
authors.forename: Karlheinz
authors.initials: K
authors.lastname: Hauenstein
authors.affiliation: Department of Child and Adolescent Psychiatry, University Medicine Rostock, Rostock, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Berger
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D060825:Cognitive Dysfunction / Q000150:complications / Q000473:pathology* / Q000503:physiopathology; D063132:Connectome / Q000379:methods*; D056324:Diffusion Tensor Imaging / Q000379:methods; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008569:Memory Disorders / Q000209:etiology / Q000473:pathology* / Q000503:physiopathology; D008570:Memory, Short-Term; D064847:Multimodal Imaging / Q000379:methods*; D009415:Nerve Net / Q000473:pathology* / Q000503:physiopathology; D066127:White Matter / Q000502:physiology
keywords: DTI; cortical activation; fMRI; fiber tracts; neurodegeneration