New research for the first time reveals the function of a little-understood junction between cells in the brain that could have important treatment implications for conditions ranging from multiple sclerosis to Alzheimer's disease, to a type of brain cancer known as glioma. Neuroscientists focused on the synapse connecting neurons to a non-neuronal cell, known as oligodendrocyte precursor cells. OPCs can differentiate into oligodendrocytes, which produce a sheath around nerves known as myelin. Myelin is the protective sheath covering each nerve cell's axon -- the threadlike portion of a cell that transmits electrical signals between cells.