This second volume of Basic and Clinical Aspects of Neuroscience is devoted to the various transmitter systems of the brain (classical and neuropeptides). In Part I the basic aspects are given, including a critical appraisal of the methods used yesterday and today to describe such neurotransmitter systems. Part II concentrates on the functioning in the body of these transmitter systems under physiologic and pathologic conditions. It goes on to show how neuroendocrine investigations may give insights into the functioning of neurotransmitter sys- tems at least in the hypothalamus, to end with a chapter which assesses very critically the errors and deficiencies of the concepts and techniques used in the attempt to understand the functioning of the brain and the mind. The editors have been fortunate to have the eight chapters written by a team of investigators working under the direction of Professor G. Fink in the MRC Brain Metabolic Unit at Edinburgh University. We are grateful to him and his colleagues for their work in writing these chapters and for the fine result they achieved. I am grateful for the editorial work done by Professor E. E. Muller (Milan) and Professor M. O. Thorner (Charlottesville), which made this volume possible. Basle, May 1987 E. Fluckiger Managing Editor Table of Contents Part I: Biochemistry of Transmitter Molecules Introduction: Role of Chemical Neurotransmission in Brain Function G.FINK References 4 Classical Transmitters and Neuromodulators 1. K. MCQUEEN Process of Synaptic Transmission. 7 Classification of Synaptic Messengers 7 Dale’s Principle …… .