Chronic ETX treatment improves white matter fractional anisotropy (FA) based on DTI. A. ETX 2–5 treated WAG/Rij rats (n = 9) exhibited a strong localized increase in FA in the midline corpus callosum (CC) and in the internal capsule (IC) compared to age-matched untreated WAG/Rij controls (n = 10). Top image is coronal slice at AP −3.6 mm and bottom image is horizontal slice extending from AP +3.6 mm to −5.6 mm. B, C. Black = untreated; Green = ETX 2–5 months treated WAG/Rij rats; B. Midline corpus callosum shows significantly increased FA, and a trend in decreased perpendicular diffusivity (λ) in ETX treated WAG/Rij rats (n = 9) compared to untreated control WAG/Rij rats (n = 10), with no change in parallel diffusivity (λ||). C. Internal capsule also exhibited significantly increased FA, along with significantly decreased λ in ETX treated WAG/Rij rats (n = 9) compared to untreated controls (n = 10), with no change in λ||.