Fig. 2.

Fractional anisotropy (FA) was sensitive at detecting long-term changes in gray and white matter following repeated mild blast exposure as well as age effects. (A) At 90 days post-injury, FA was increased in injured rats relative to age-matched controls in gray matter of olfactory regions (Olf), anterior hypothalamus (AHyp), the centromedial thalamic nucleus (CM), hippocampus (Hc), periaqueductal gray (PAG), cerebellum, and gigantocellular reticular nucleus (Gi). White matter tracts marked by FA increases included the cerebral peduncles (cp), inferior cerebellar peduncle (icp), spinal trigeminal tract (sp5), and cerebellar white matter (cbw). (B) Age-related changes in FA, consistent with normal neurodevelopment, were extensive in white and gray matter. Voxel-wise data are presented as t maps, cluster-corrected for multiple comparisons, and thresholded at the 0.05 significance level; R = right (ipsilateral hemisphere), L = left (contralateral hemisphere); scalebar = 2 mm. (C) FA (unitless) was significantly higher at 90 days post-injury (or sham) for white matter regions of interest. ROI data are presented as box plots where red line = median, box = quartiles, whiskers = range, + = outliers; significant group differences (p < .05) are denoted as follows: * age-related changes in control rats; ** age-related changes in injured rats. Key: yc, young control; yb, young blast; oc, old control; ob, old blast.