Abstract
Aging has a multi-faceted impact on brain structure, brain function and cognitive task performance, but the interaction of these different age-related changes is largely unexplored. We hypothesize that age-related structural changes alter the functional connectivity within the brain, resulting in altered task performance during cognitive challenges. In this neuroimaging study, we used independent components analysis to identify spatial patterns of coordinated functional activity involved in the performance of a verbal delayed item recognition task from 75 healthy young and 37 healthy old adults. Strength of functional connectivity between spatial components was assessed for age group differences and related to speeded task performance. We then assessed whether age-related differences in global brain volume were associated with age-related differences in functional network connectivity. Both age groups used a series of spatial components during the verbal working memory task and the strength and distribution of functional network connectivity between these components differed across the age groups. Poorer task performance, i.e. slower speed with increasing memory load, in the old adults was associated with decreases in functional network connectivity between components comprised of the supplementary motor area and the middle cingulate and between the precuneus and the middle/superior frontal cortex. Advancing age also led to decreased brain volume; however, there was no evidence to support the hypothesis that age-related alterations in functional network connectivity were the result of global brain volume changes. These results suggest that age-related differences in the coordination of neural activity between brain regions partially underlie differences in cognitive performance.
Highlights
Advancing age is associated with decline in multiple cognitive domains, including verbal working memory (WM)
The present study examines how the strength of functional connectivity between broad networks of brain regions during performance of a verbal working memory task relates to task performance
Based on this letter set size related finding, the letter set size dependent effect on response times was calculated and was significantly larger in the older adults than the young (F(1,108) = 14.38, two-tailed p,0.001), there was no main effect of gender (F(1,108) = 0.013, p.0.05), nor an interaction of gender and age group (F(1,108) = 0.059, p.0.05)
Summary
Advancing age is associated with decline in multiple cognitive domains, including verbal working memory (WM). Encoding, maintaining and retrieving information using verbal working memory involves the coordination of multiple neural processes. The brain regions sub-serving these processes have been elucidated with experimental manipulations that vary task demands by altering the information load [2,3,4], retention interval [5,6] and response time duration [7,8]. Advancing age is associated with decreased performance on verbal working memory in the face of increasing task demands [10]. The underlying cause for these cognitive changes is assumed to partly be age-related neural changes [11] in global and regional brain volume, white matter hyperintensity burden and cerebral blood flow. Aging and disease have been related to changes in the functional connectivity of brain regions in the absence of external stimulation [12,13,14,15]
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