FIG. 6.

Results of between-group interaction effects suggesting mild TBI as a moderator in the relationships between the diffusion metrics and neuropsychological outcome measures. (A) The color-coded matrix summarizes the total number of white matter voxels having significant interaction effects in the TBSS analyses. The cold colors indicate the correlation coefficient (ρ) is lower in the mild TBI group compared to the control group, whereas the warm colors indicate the opposite. (B) Results of post-hoc regression analyses for the five V_ic-neuropsychological pairs that had significant TBSS results in (A). Each black dot denotes 1 individual in the trauma control group, and the red triangle denotes an individual in the mild TBI group. The coefficient of determination for the interaction model (R²) and the significance of the moderator variable (p_int) in the interaction model are reported in the subpanels. The interaction model was a general linear model with an interaction between the group membership (as moderator variable) and diffusion metrics: neuropsychological_outcome = β₀ + β₁·group + β₂·diffusion_metric + β₃·group·diffusion_metric + covariates + error. (C) Anatomical distributions of white matter voxels with significant between-group interactions in the TBSS analyses of V_ic-neuropsychological measures. The horizontal axis denotes the Johns Hopkins University (JHU) white matter labels in Figure 1 with the length of the interval reflecting its three-dimensional size (in cubic root) in the atlas. The color denotes the percentage (%) of voxels in the labeled white mater tract with significant interaction effects. mTBI, mild traumatic brain injury; TBSS, tract-based spatial statistics.