The group of chemicals known collectively as neurotransmitters form the basis of a complex communication system between nerve cells. It is a system which is constantly subtly refined and regulated via the modulating action of other neurotransmitters, circulating hormones, the products of local tissues and the action of various drugs (from both medicinal and socially abused sources). Within this book, acknowledged authorities concisely describe the basic mechanisms involved in neurotransmitter release modulation in the different parts of the nervous system. This includes a quantitative evaluation of the significance of modulation, and a summary of both its biological ramifications and potential clinical relevance. The clear illustrations and descriptions create a valuable and easy to use reference resource for the non-specialist reader and neuroscientist alike. Clinicians, researchers and students should all find its contents of interest.