Multiple sclerosis (MS) is a debilitating autoimmune disease in which immune cells infiltrate the central nervous system and attack the myelin sheath surrounding axons.  Dr. Simons explains that myelin is necessary for signal conduction by nerve cells and for the metabolic support of axons. Demyelination results in axonal loss and formation of lesions in the brain. A small percentage of MS lesions are capable of remyelination following steps similar to axonal myelination during normal development.  Since lesion remyelination correlates with reduced neurodegeneration, Simons and his colleagues strive to understand why remyelination occurs in only a small number of MS patients and to identify drugs that may promote it.