"Other researchers, like Dr. Fields, uncovered the mechanism by which these myelin increases happened. As he described in a 2006 paper in the journal Neuron, supporter cells called oligodendrocytes and astrocytes sense the nerve firing and respond by wrapping more myelin on the fiber that fires. The more the nerve fires, the more myelin wraps around it. The more myelin wraps around it, the faster the signals travel, increasing velocities up to one hundred times over signals sent through an uninsulated fiber." - Daniel Coyle