Fig. 4. Maturation of between-network coupling aligns with the position of each network in the functional hierarchy.
a Mean between-network coupling is largely captured by relative position along the sensorimotor to association axis. The inter-network coupling of each pair of networks at each scale is modeled using a GAM to estimate their values at age 8. Here, those values are plotted versus the difference in the hierarchical position of the two networks being evaluated. Each data point represents the coupling of a network pair at a given scale. Each half of the circle is colored according to constituent networks’ maximum overlap with the 7-network solution defined by Yeo et al. (2011); network pairs that do not significantly change with age after FDR correction (Q < 0.05) are shaded in gray. As expected, networks at a similar position along the functional hierarchy tend to have higher coupling (r = −0.568, β = −0.012, pboot < 0.001, two-sided). b Age effects quantifying the development of between-network coupling is similarly aligned with the relative position of networks along the functional hierarchy. Age effects of every network pair at each scale are plotted versus their hierarchical distance and colored as in a. Network pairs without significant age effects are plotted in gray. Developmental effects on pairwise coupling between networks are associated with the hierarchical distance between networks (r = −0.49, pboot < 0.001, two-sided). c Top: schematic summarizing developmental effects. Development is associated with strengthening of network coupling between lower-order networks and weakening of coupling between lower and higher-order networks; thicker lines represent greater functional coupling. Bottom: topographical plot of the observed age effect as a function of absolute (rather than relative) network hierarchy values across all network pairs. Increased coupling with age between functionally similar networks is prominent for sensorimotor networks (bottom left), and less prominent for association networks (top right). Age-related decreases in coupling occur in sensorimotor-association network pairs (top left and bottom right).