Fig. 3.

Illustration of a graph. Graphs are made up of nodes and lines called edges that connect them (a). With the use of graph theory, researchers have characterized the small-world architecture of neural networks. Structurally and functionally related regions are densely connected within hubs, or modules; these modules are sparsely connected with each other (b).

Adapted from Bullmore and Sporns (2009). Reprinted by permission from Macmillan Publishers Ltd: [Nature Reviews Neuroscience] copyright (2009).