Brain topology underlying executive functions across the lifespan: focus on the default mode network

While traditional neuroimaging approaches to the study of executive functions (EFs) have typically employed task-evoked paradigms, resting state studies are gaining popularity as a tool for investigating inter-individual variability in the functional connectome and its relationship to cognitive performance outside of the scanner. Using resting state functional magnetic resonance imaging data from the Human Connectome Project Lifespan database, the present study capitalised on graph theory to chart cross-sectional variations in the functional organisation of the frontoparietal (FPN) and the default mode (DMN) networks in 135 healthy individuals (from 10 to 100 years of age), in order to investigate the neural underpinnings of EFs across the lifespan. Topological properties of both the FPN and the DMN were observed to predict EF performance, providing support for a tight link between neuro-functional and cognitive-behavioural efficiency. The topological organisation of the DMN, however, appeared more sensitive to age-related changes relative to that of the FPN. Moreover, both the topological properties of the DMN at a network level, as well as of its single regions, were predictive of EF performance, while the topology of only single regions within the FPN exhibited a similar pattern. Because the DMN is present and matures earlier in life than the FPN, and because its activity is stronger in conditions of resting state, the DMN might be easier to measure in noncompliant populations, and the study of its functional architecture in relation to higher order cognition across the lifespan might, thus, be of greater interest compared with other resting state networks.