title: Changes of intranetwork and internetwork functional connectivity in Alzheimer's disease and mild cognitive impairment.
abstract: Alzheimer's disease (AD) is a serious neurodegenerative disorder characterized by deficits of working memory, attention, language and many other cognitive functions. Although different stages of the disease are relatively well characterized by clinical criteria, stage-specific pathological changes in the brain remain relatively poorly understood, especially at the level of large-scale functional networks. In this study, we aimed to characterize the potential disruptions of large-scale functional brain networks based on a sample including amnestic mild cognition impairment (aMCI) and AD patients to help delineate the underlying stage-dependent AD pathology.
  
  
  
  We sought to identify the neural connectivity mechanisms of aMCI and AD through examination of both intranetwork and internetwork interactions among four of the brain's key networks, namely dorsal attention network (DAN), default mode network (DMN), executive control network (ECN) and salience network (SAL). We analyzed functional connectivity based on resting-state functional magnetic resonance imaging (rs-fMRI) data from 25 Alzheimer's disease patients, 20 aMCI patients and 35 elderly normal controls (NC).
  
  
  
  Intranetwork functional disruptions within the DAN and ECN were detected in both aMCI and AD patients. Disrupted intranetwork connectivity of DMN and anti-correlation between DAN and DMN were observed in AD patients. Moreover, aMCI-specific alterations in the internetwork functional connectivity of SAL were observed.
  
  
  
  Our results confirmed previous findings that AD pathology was related to dysconnectivity both within and between resting-state networks but revealed more spatial details. Moreover, the SAL network, reportedly flexibly coupling either with the DAN or DMN networks during different brain states, demonstrated interesting alterations specifically in the early stage of the disease.
authors.affiliation: School of Precision Instrument And Opto-electronics Engineering, Tianjin University, Tianjin, People's Republic of China.
authors.forename: Haoze
authors.initials: H
authors.lastname: Zhu
authors.forename: Peng
authors.initials: P
authors.lastname: Zhou
authors.forename: Sarael
authors.initials: S
authors.lastname: Alcauter
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Chen
authors.forename: Hongbao
authors.initials: H
authors.lastname: Cao
authors.forename: Miao
authors.initials: M
authors.lastname: Tian
authors.forename: Dong
authors.initials: D
authors.lastname: Ming
authors.forename: Hongzhi
authors.initials: H
authors.lastname: Qi
authors.forename: Xuemin
authors.initials: X
authors.lastname: Wang
authors.forename: Xin
authors.initials: X
authors.lastname: Zhao
authors.forename: Feng
authors.initials: F
authors.lastname: He
authors.forename: Hongyan
authors.initials: H
authors.lastname: Ni
authors.forename: Wei
authors.initials: W
authors.lastname: Gao
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000503:physiopathology*; D000647:Amnesia / Q000503:physiopathology; D001288:Attention / Q000502:physiology; D001921:Brain / Q000503:physiopathology; D001931:Brain Mapping; D060825:Cognitive Dysfunction / Q000503:physiopathology*; D056344:Executive Function; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000503:physiopathology*; D009434:Neural Pathways / Q000503:physiopathology*