Brain Signal Variability and Executive Functions Across the Lifespan

Abstract Neural variability is thought to facilitate survival through flexible adaptation to changing environmental demands. In humans, such capacity for flexible adaptation may manifest as fluid reasoning, inhibition of automatic responses, and mental set-switching – skills falling under the broad domain of executive functions which fluctuate over the lifespan. Neural variability can be quantified via the blood-oxygenated level-dependent (BOLD) signal in resting-state functional magnetic resonance imaging (fMRI). Variability of large-scale brain networks is posited to underpin complex cognitive activities requiring interactions between multiple brain regions. Few studies have examined the extent to which network-level brain signal variability across the lifespan maps onto high-level processes under the umbrella of executive functions. The present study leveraged a large publicly available neuroimaging dataset to investigate the relationship between signal variability and executive functions across the lifespan. Associations between brain signal variability and executive functions shifted as a function of age. Limbic-specific variability was consistently associated with greater performance across subcomponents of executive functions. Associations between executive function subcomponents and network-level variability of the default mode and central executive networks, as well as whole-brain variability, varied across the lifespan. Findings suggest brain signal variability may help to explain to age-related differences in executive functions across the lifespan.