Absence epilepsy is a form of generalized epilepsy, common in pediatric populations, which causes seizures with brief lapses in awareness. Electron microscopy (EM) results in rat and mouse models of absence epilepsy support the hypothesis that maladaptive myelination plays a role in the progression of this disease. However, common EM histology techniques used to measure myelination require that the animal be sacrificed, making it not compatible with longitudinal studies, and the histology techniques are also normally limited to tiny subsections of tissue. To enable whole-brain, longitudinal assessment of white matter changes, we propose to develop in vivo quantitative magnetic resonance imaging (MRI) methods and to validate them against electron microscopy and tissue clearing histology. We anticipate that the proposed MRI technology will reveal the hypothesized interplay between myelination and seizure activity that is critical to a better understanding of absence epilepsy and the development and assessment of new treatments.