title: Decreased activity with increased background network efficiency in amnestic MCI during a visuospatial working memory task.
abstract: Recent studies have demonstrated the working memory impairment in patients with amnestic mild cognitive impairment (aMCI). However, the neurophysiological basis of the working memory deficit in aMCI is poorly understood. The aim of this study was to explore the abnormal activity during encoding and recognition procedures, as well as the reorganization of the background network maintaining the working memory state in aMCI. Using event-related fMRI during a visuospatial working memory task with three recognition difficulty levels, the task-related activations and network efficiency of the background network in 17 aMCI patients and 19 matched controls were investigated. Compared with cognitively healthy controls, patients with aMCI showed significantly decreased activity in the frontal and visual cortices during the encoding phase, while during the recognition phase, decreased activity was detected in the frontal, parietal, and visual regions. In addition, increased local efficiency was also observed in the background network of patients with aMCI. The results suggest patients with aMCI showed impaired encoding and recognition functions during the visuospatial working memory task, and may pay more effort to maintain the cognitive state. This study extends our understanding of the impaired working memory function in aMCI and provides a new perspective to investigate the compensatory mechanism in aMCI.
authors.affiliation: Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Hong Kong.|Research Center for Medical Image Computing, The Chinese University of Hong Kong, Hong Kong.
authors.forename: Wutao
authors.initials: W
authors.lastname: Lou
authors.affiliation: Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong.|Chow Yuk Ho Center of Innovative Technology for Medicine, The Chinese University of Hong Kong, Hong Kong.
authors.forename: Lin
authors.initials: L
authors.lastname: Shi
authors.affiliation: Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Hong Kong.|Research Center for Medical Image Computing, The Chinese University of Hong Kong, Hong Kong.|Department of Biomedical Engineering and Shun Hing Institute of Advanced Engineering, The Chinese University of Hong Kong, Hong Kong.|Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China.
authors.forename: Defeng
authors.initials: D
authors.lastname: Wang
authors.affiliation: Department of Psychiatry, North District Hospital, Hong Kong.
authors.forename: Cindy W C
authors.initials: CW
authors.lastname: Tam
authors.affiliation: Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Hong Kong.
authors.forename: Winnie C W
authors.initials: WC
authors.lastname: Chu
authors.affiliation: Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong.
authors.forename: Vincent C T
authors.initials: VC
authors.lastname: Mok
authors.affiliation: Department of Health and Physical Education, Hong Kong Institute of Education, Hong Kong.|Department of Clinical Psychology, Norwich Medical School, University of East Anglia, Norfolk, United Kingdom.
authors.forename: Sheung-Tak
authors.initials: ST
authors.lastname: Cheng
authors.affiliation: Department of Psychiatry, The Chinese University of Hong Kong, Hong Kong.
authors.forename: Linda C W
authors.initials: LC
authors.lastname: Lam
mesh_terms: D000368:Aged; D000647:Amnesia / Q000503:physiopathology / Q000523:psychology; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D060825:Cognitive Dysfunction / Q000503:physiopathology* / Q000523:psychology; D005260:Female; D006801:Humans; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D009434:Neural Pathways / Q000503:physiopathology; D009483:Neuropsychological Tests; D021641:Recognition, Psychology / Q000502:physiology; D013028:Space Perception / Q000502:physiology*
keywords: Functional MRI; amnestic mild cognitive impairment; background functional connectivity; brain network; visuospatial working memory