In this book we attempt a synthesis of knowledge from two investigative extremes. On the one hand, neurophysiology and neuropharmacology are progressing via the single neuron to a subcellular level; on the other, clinicians are studying the function of the human urinary system in vivo as a whole. A special effort must be made over the next decade to bridge this gap. We hope that the information summarized here will catalyse the process. In 1968, de Groat and Ryall published a group of papers in the Journal of Physiology in which modern quantitative electrophysiological techniques were applied to the study of the reflexes that regulate bladder Junction. These papers represent alandmark in the history of bladder neurophysiology, forming a dividing li ne between old and new. The earlier techniques of lesioning and stimulation of nervous structures yielded mainly qualitative information which was open to criticism because of lack of precise control over what was actually being destroyed or stimulated. Much of this earlier work was reviewed in an authoritative volume by Bors and Comarr in 1971, entitled Neurolqgical Urology. The 16 years have seen great advances in our understanding of the control oflower subsequent urinary tract function.