Figure 1. Modularity. (A) Schematic network plot showing a set of nodes and edges interconnected to form two relatively distinct modules (communities). Note that the two modules are linked via a single hub node (black) that maintains two bridges between the two modules. Panels (B) to (E) use a 77-node data set from reference 74, representing the 77 areas and directed weighted projections of the rat cerebral cortex. (B) The plot at the top illustrates the varying number of modules as the value of the resolution parameter is increased from 0.1 to 4.0. The number of detected modules increases from 1 to 22 within this range. (C) The matrix plot represents the variation of information between all detected partitions within the range of the resolution parameter plotted above. Dark blue corresponds to a variation of information (distance) of zero, ie, identity. The region around gamma=0.7 is the most homogeneous region within the range. (D) The rat cerebral cortex connection matrix (weights displayed on log-scale), reordered by module assignment for gamma=0.7. The three modules are indicated with white boundaries. (E) The multiscale co-assignment matrix, computed using the method described in ref. 37. Co-assignment varies between 1 (node pair in same module at all scales) to 0 (node pair never co-assigned at any scale). Tree plot at the bottom shows all hierarchically clustered solutions, with the top one corresponding to the same three modules shown in panel (C). Within each of the three modules, additional modular structure is detected.