Joint contributions from brain activity and activity-independent
functional connectivity to working memory aging
Abstract
Working memory (WM) impairment has been well characterized in normal
ageing. Various studies have explored changes in either the regional
activity or the interregional connectivity underlying the WM ageing
process. We proposed that brain activity and connectivity would
independently alter with ageing and affect WM performance. WM was
assessed with a classical N-back task during functional magnetic
resonance imaging in a community-based sample comprising 168 elderly
subjects (aged 55 to 86 years old). Following the rationale of
background functional connectivity, we assessed age-related alterations
in brain activity and seed-based interregional connectivity
independently. Analyses revealed age-related decrease in the activity of
the inferior parietal lobule (IPL) and an increase in the activity of
the ventral anterior cingulate cortex (ACC), and the local functional
dysfunctions were accompanied by alterations in their connectivity to
other cortical regions. Importantly, regional activity impairments in
the IPL and ACC could mediate age-related effects on accuracy rate and
reaction time, respectively, and those effects were further
counterbalanced by enhancement of their background functional
connectivity. We thus claimed that age-induced alterations in regional
activity and interregional connectivity occurred independently and
contributed to WM changes in ageing. Our findings presented the way
brain activity and functional connectivity interact in the late
adulthood, thus providing a new perspective for understanding WM and
cognitive ageing.