Age Differences in the Functional Interactions among the Default, Frontoparietal Control and Dorsal Attention Networks

• Published in: Neurobiology of aging Vol. 41; pp. 159 - 172
• Main Authors: Grady, Cheryl, Sarraf, Saman, Saverino, Cristina, Campbell, Karen
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.05.2016
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Aging; Aging - psychology; Brain - diagnostic imaging; Brain - physiology; Cognition - physiology; Cognitive control; Female; fMRI; Frontoparietal control network; Functional connectivity; Graph theory; Humans; Internal Medicine; Magnetic Resonance Imaging; Male; Memory; Memory - physiology; Middle Aged; Nerve Net - physiology; Neurology; Young Adult; fMRI; cognitive control; functional connectivity; memory; graph theory; frontoparietal control network; aging; Functional connectivity; Frontoparietal control network; Memory; Aging; Graph theory; Cognitive control
• ISSN: 0197-4580; 1558-1497
• DOI: 10.1016/j.neurobiolaging.2016.02.020

Abstract Older adults typically show weaker functional connectivity within brain networks compared to young adults, but stronger functional connections between networks. Our primary aim here was to use a graph theoretical approach to identify age differences in the functional connectivity of three networks - default (DMN), dorsal attention (DAN) and frontoparietal control (FPC) – during rest and task conditions, and to test the hypothesis that age differences in the FPC would influence age differences in the other networks, consistent with its role as a cognitive “switch”. At rest, older adults showed lower clustering values compared to the young, and both groups showed more between-network connections involving the FPC than the other two networks, but this difference was greater in the older adults. Connectivity within the DMN was reduced in older compared to younger adults. Consistent with our hypothesis, between-network connections of the FPC at rest predicted the age-related reduction in connectivity within the DMN. There was no age difference in within-network functional connectivity during the task (after removing the specific task effect), but between-network connections were greater in older adults than in young adults for the FPC and DAN. In addition, age reductions were found in almost all of the graph metrics during the task condition, including clustering and modularity. Finally, age differences in between-network connectivity of the FPC during both rest and task predicted cognitive performance. These findings provide additional evidence of less within-network but greater between-network functional connectivity in older adults during rest, but also show that these age differences can be altered by the residual influence of task demands on background connectivity. Our results also support a role for the FPC as the regulator of other brain networks in the service of cognition. Critically, the link between age differences in inter-network connections of the FPC and DMN connectivity, and the link between FPC connectivity and performance, support the hypothesis that functional connectivity of the FPC influences the expression of age differences in other networks, as well as differences in cognitive function.