1. Myelinated Axons: 35 to 75 M/s; Unmyelinated Axons: 0.1 to 5 M/s; Axon diameter Larger diameter Axons: Conduct at faster velocities; Axon atrophy: Reduces rate of axonal conduction; Myelin thickness: Thickly-myelinated fibers conduct more rapidly Myelin layers "insulate" axon: Depolarization occurs only at nodes of Ranvier