This is a timely review of the mechanisms underlying the presynaptic control of synaptic transmission and the role they play in sensory and motor behavior. Early chapters offer a detailed account of the anatomy, biophysics, and physiology of synaptic transmission at the peripheral and central synapses, focusing on the presynaptic control of transmitter release. Later chapters explore the organization of neural pathways leading to the presynaptic inhibition of transmitter release in segmental reflex pathways. A final section provides examples of the operation of presynaptic control mechanisms...