Fig. 1.

Short- and long-term changes in volume between injured and sham rats. (A) At 7 days post-injury, local gray matter volume increases were noted in injured rats in the olfactory (Olf) and frontal association (FrA) cortex, striatum, cingulate and motor (M1/M2) cortex, thalamus (Thal), substantia nigra (SNR, reticular part), tectum (superior colliculus), median and dorsal raphe nuclei (MnR and DR, respectively), and the isthmic reticular nucleus (Re). Among white matter tracts, the internal capsule (ic) and cerebral peduncle (cp) appeared unilaterally enlarged. (B) At 90 days post-injury, we noted volume reductions in the cingulate cortex (Cg), caudate putamen (CPu), and globus pallidus, as well as the thalamus, hippocampus (Hc), and postsubiculum (Post). White matter tracts with reduced volume included the corpus callosum, fimbria (fi), internal capsule (ic), cerebral peduncle (cp), posterior commissure (pc), and cerebellar white matter (cbw). (C) Age-related changes in control rats (2-month vs. 5-month old) were predominantly marked by volume increases, particularly in the hindbrain, with variable reductions in the gray matter volume of piriform, hypothalamic, and hippocampal regions. (D) Interactions on volume were predominantly negative in the CPu, globus pallidus (GP), bed nucleus of the stria terminalis (BNST), thalamus, SNR, and tectum (superior and inferior colliculus). A negative interaction was also observed for white matter tracts including the anterior commissure (ac), fi, ic, cp, and optic tract (ot). In contrast, areas of the hippocampus (Hc) and amygdala (Amy) showed positive interactions (unilateral). 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. (E) Total brain volume (mm³) and normalized regional volumes (% of brain) at 7 and 90 days post-injury (or sham). 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; ^# injury-related differences between age-matched groups. Key: IC, inferior colliculus; LD, laterodorsal thalamic nucleus; MG, medial geniculate nucleus; Spt, septum; Ve, vestibular nuclei; yc, young control; yb, young blast; oc, old control; ob, old blast.