RT Journal Article
SR Electronic
T1 Older adults benefit from more widespread brain network integration during working memory
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 642447
DO 10.1101/642447
A1 C.A. Crowell
A1 S.W. Davis
A1 L. Beynel
A1 L. Deng
A1 D. Lakhlani
A1 S.A. Hilbig
A1 H. Palmer
A1 A. Brito
A1 J. Wang
A1 A. V Peterchev
A1 B. Luber
A1 S.H. Lisanby
A1 L.G. Appelbaum
A1 R. Cabeza
YR 2019
UL http://biorxiv.org/content/early/2019/05/20/642447.abstract
AB Neuroimaging evidence suggests that the aging brain relies on a more distributed set of cortical regions than younger adults in order to maintain successful levels of performance during demanding cognitive tasks. However, it remains unclear how task demands give rise to this age-related expansion in cortical networks. To investigate this issue, we used functional magnetic resonance imaging to measure univariate activity, network connectivity, and cognitive performance in younger and older adults during a working memory (WM) task. In the WM task investigated, participants hold letters online (maintenance) while reordering them alphabetically (manipulation). WM load was titrated to obtain four individualized difficulty levels. Network integration—defined as the ratio of within-versus between-network connectivity—was linked to individual differences in WM capacity. The study yielded three main findings. First, as task difficulty increased, network integration decreased in younger adults, whereas it increased in older adults. Second, age-related increases in network integration were driven by increases in right hemispheric connectivity to both left and right cortical regions, a finding that helps to reconcile extant theories of compensatory recruitment in aging to address the multivariate dynamics of global network functioning. Lastly, older adults with higher WM capacity demonstrated higher levels of network integration in the most difficult condition. These results shed light on the mechanisms of age-related network reorganization by suggesting that changes in network connectivity may act as an adaptive form of compensation, with older adults recruiting a more distributed cortical network as task demands increase.Significance statement Older adults often activate brain regions not engaged by younger adults, but the circumstances under which this widespread network emerges are unclear. Here, we examined the effects of aging on network connectivity between task regions recruited during a working memory (WM) manipulation task, and the rest of the brain. We found an age-related increase in the more global network integration in older adults, and an association between this integration and working memory capacity in older adults. The findings are generally consistent with the compensatory interpretation of these effects.