title: Age-related alterations in default mode network: impact on working memory performance.
abstract: The default mode network (DMN) is a set of functionally connected brain regions which shows deactivation (task-induced deactivation, TID) during a cognitive task. Evidence shows an age-related decline in task-load-related modulation of the activity within the DMN during cognitive tasks. However, the effect of age on the functional coupling within the DMN and their relation to cognitive performance has hitherto been unexplored. Using functional magnetic resonance imaging, we investigated functional connectivity within the DMN in older and younger subjects during a working memory task with increasing task load. Older adults showed decreased connectivity and ability to suppress low frequency oscillations of the DMN. Additionally, the strength of the functional coupling of posterior cingulate (pCC) with medial prefrontal cortex (PFC) correlated positively with performance and was lower in older adults. pCC was also negatively coupled with task-related regions, namely the dorsolateral PFC and cingulate regions. Our results show that in addition to changes in canonical task-related brain regions, normal aging is also associated with alterations in the activity and connectivity of brain regions within the DMN. These changes may be a reflection of a deficit in cognitive control associated with advancing age that results in deficient resource allocation to the task at hand.
authors.affiliation: Genes, Cognition, and Psychosis Program, Clinical Brain Disorders Branch, National Institute of Mental Health Intramural Research Program, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Fabio
authors.initials: F
authors.lastname: Sambataro
authors.forename: Vishnu P
authors.initials: VP
authors.lastname: Murty
authors.forename: Joseph H
authors.initials: JH
authors.lastname: Callicott
authors.forename: Hao-Yang
authors.initials: HY
authors.lastname: Tan
authors.forename: Saumitra
authors.initials: S
authors.lastname: Das
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Weinberger
authors.forename: Venkata S
authors.initials: VS
authors.lastname: Mattay
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D000704:Analysis of Variance; D001931:Brain Mapping; D016009:Chi-Square Distribution; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006179:Gyrus Cinguli / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D008875:Middle Aged; D009415:Nerve Net / Q000502:physiology*; D009434:Neural Pathways / Q000502:physiology; D009483:Neuropsychological Tests; D017397:Prefrontal Cortex / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology