Kundu S, et al. - Through a retrospective study of 64 postconcussive patients who underwent diffusion tensor images (DTI) between January 2006 and March 2013, the researchers identified white matter injury underlying reaction time in mild traumatic brain injury DTI by applying transport-based morphometry. Following the correction of covariates of age, sex, and time from injury, the direction in the transport space most associated with reaction time was observed as significant. Inverting the computed direction via transport-based morphometry demonstrated physical shifts in fractional anisotropy in the corpus callosum (increase) and within the optic radiations, corticospinal tracts, and anterior thalamic radiations (decrease) with decreasing reaction time. The noted shifts were consonant with biologic pathways underlying the visual-spatial interpretation and response-selection aspects of reaction time. Hence, transport-based morphometry ascertained complex white matter injury underlying postconcussive reaction time in an automated manner. The potential impacts of edema and axonal loss were imaged in the visual-spatial interpretation and response-selection pathways. Moreover, transport-based morphometry could fill the gap between brain microstructure and function in conditions in which the structural basis was unknown.