1Physics, Washington University , St. Louis, MO, United States; 2Radiology, Washington University School of Medicine, St. Louis, MO, United States; 3The Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO, United States; 4Neurology, Washington University School of Medicine, St. Louis, MO, United States; 5Neurology, Washington University in St. Louis, St. Louis, MO, United States
Our previous investigation in healthy mice has shown that visual stimulation caused a significant (~27%) drop in the apparent diffusion coefficient for water perpendicular to the axonal fibers (ADC) in optic nerve. In the current study, we have extended these diffusion fMRI measurements in a mouse experimental autoimmune encephalomyelitis (EAE) model at the onset of optic neuritis to investigate the functional integrity of white matter. Our results show that visual stimulation produced a significant 25% decrease in ADC in EAE sham optic nerves, while only a 5% decrease in ADC was seen in EAE mice. Histological results of SMI31, MBP, and SMI32 staining show axonal swelling and injury distorted myelin sheaths in EAE optic nerves. This suggests that diffusion fMRI could be used as a non-invasive approach to localizing axons with impaired functional integrity.