Figure 1. .

TBI-induced alterations to structural networks revealed by diffusion tensor imaging. (a) Hierarchical tree or dendrogram defining a hierarchal brain partition (Diez, Bonifazi, et al., 2015) in which three different levels of the tree have been emphasized: M = 1, where all brain regions belong to a single module; M = 20, the optimal brain partition (see Materials and Methods); and M = 120, the level at which structural connectivity was higher in TBI patients than in controls. Group differences were calculated on module degree maps derived from the intermodule connectivity matrix and after a two-sample t-test with age and head motion as covariates of noninterest (p 0.05). Multiple comparison corrections were achieved by applying subject-label permutations, thereby building the a null-hypothesis distribution, since all correlations were removed by this shuffling. Greater connectivity in controls than in TBI patients (red scale) was found at M = 20, and at M = 120, TBI control connectivity was also found (blue scale). Brain maps represent values of the t-statistic. (b)At M = 20 (left graph), significant control TBI connectivity was evident in Module 14 (including parts of the hippocampus and parahippocampal gyrus, amygdala, putamen, insula, ventral diencephalon, temporal gyrus, and temporal pole) and Module 20 (including parts of the cerebellum and parahippocampal gyrus). At M = 120 (right graph), TBI control connectivity was found within Module 11, including parts of the rectus and superior and inferior frontal orbital gyri. The module colors are just indicative and coincide with the colors used in Diez, Bonifazi, et al. (2015), where we first published the hierarchical brain atlas.