title: Disturbed default mode network connectivity patterns in Alzheimer's disease associated with visual processing.
abstract: Changes in connectivity of the posterior node of the default mode network (DMN) were studied when switching from baseline to a cognitive task using functional magnetic resonance imaging. In all, 15 patients with mild to moderate Alzheimer's disease (AD) and 18 age-, gender-, and education-matched healthy controls (HC) participated in the study. Psychophysiological interactions analysis was used to assess the specific alterations in the DMN connectivity (deactivation-based) due to psychological effects from the complex visual scene encoding task. In HC, we observed task-induced connectivity decreases between the posterior cingulate and middle temporal and occipital visual cortices. These findings imply successful involvement of the ventral visual pathway during the visual processing in our HC cohort. In AD, involvement of the areas engaged in the ventral visual pathway was observed only in a small volume of the right middle temporal gyrus. Additional connectivity changes (decreases) in AD were present between the posterior cingulate and superior temporal gyrus when switching from baseline to task condition. These changes are probably related to both disturbed visual processing and the DMN connectivity in AD and reflect deficits and compensatory mechanisms within the large scale brain networks in this patient population. Studying the DMN connectivity using psychophysiological interactions analysis may provide a sensitive tool for exploring early changes in AD and their dynamics during the disease progression.
authors.affiliation: First Department of Neurology, School of Medicine, Masaryk University, Brno, Czech Republic Applied Neuroscience Research Group, CEITEC - Central European Institute of Technology, Masaryk University, Brno, Czech Republic.
authors.forename: Lenka
authors.initials: L
authors.lastname: Krajcovicova
authors.affiliation: Multimodal and Functional Imaging Research Group, CEITEC - Central European Institute of Technology, Masaryk University, Brno, Czech Republic.
authors.forename: Michal
authors.initials: M
authors.lastname: Mikl
authors.affiliation: Multimodal and Functional Imaging Research Group, CEITEC - Central European Institute of Technology, Masaryk University, Brno, Czech Republic.
authors.forename: Radek
authors.initials: R
authors.lastname: Marecek
authors.affiliation: First Department of Neurology, School of Medicine, Masaryk University, Brno, Czech Republic Applied Neuroscience Research Group, CEITEC - Central European Institute of Technology, Masaryk University, Brno, Czech Republic.
authors.forename: Irena
authors.initials: I
authors.lastname: Rektorova
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000473:pathology*; D001921:Brain / Q000098:blood supply / Q000503:physiopathology*; D001931:Brain Mapping; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D009415:Nerve Net / Q000098:blood supply / Q000473:pathology*; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood; D014795:Visual Pathways / Q000098:blood supply / Q000503:physiopathology*
chemical_list: D010100:Oxygen
keywords: Alzheimer's disease; default mode network; functional MRI; posterior cingulate; visual processing