Figure 2.

Rich-club curves and magnitude of developmental changes in peripheral, feeder, and hub–hub connections. a shows the normalized rich-club coefficients, Φ_norm^w(k) (red), for the follow-up group-averaged streamline density-weighted network. Weighted rich-club coefficients, φ^w(k) (black), were found to be significantly greater than those derived from randomized networks, φ_rand^w(k) (gray), for a range of k from 30 to 72 (one-tailed, p < 0.05; filled/solid red markers), indicating robust rich-club organization in the network. b and c show the percentage difference between observed and expected proportions at each level of k for each connection type [peripheral (yellow), feeder (orange), and hub–hub (red)] in the subnetwork showing decreased streamline density over time (b) and the subnetwork showing increased streamline density over time (c). χ² analysis of the difference between the observed and expected proportions (also at each level of k) revealed a significant effect of connection type (p < 0.05; filled/solid markers) in both the subnetwork showing decreased streamline density over time (for each k in the range 27 < k < 36 except k = 31, and 45 < k < 73; b) and the subnetwork showing increased streamline density over time (for each k in the range 30 < k < 62 except k = 54; c). As can be seen, a disproportionate number of hub–hub connections showed developmental changes, particularly at levels of k that coincide with the topological rich-club effect (a).