What is the benefit of increased long-range and/or decreased short-range rs-fcMRI correlations? At present, we can only speculate. It is plausible, and even probable, that increases in coherent activity within functional systems might facilitate particular cognitive abilities. In adults, rs-fcMRI correlations and network properties have been linked to measures such as IQ or task performance (Seeley et al., 2007; van den Heuvel et al., 2009). We are unaware of any developmental studies examining such relationships. Unfortunately, over childhood and adolescence, changes in functional connectivity will likely correlate with many behavioral or physiologic measures, such as height or hormonal levels, as well as various cognitive measures. Developmental studies of correlates between rs-fcMRI measures and cognitive or behavioral measures will therefore need tightly constrained hypotheses, or large datasets that can achieve the power needed to tease apart such covariance.
