The eighth edition of Campbell's Psychiatric Dictionary continues to pursue its goal of keeping the reader abreast of new development in psychiatry. Technological advances have enabled researchers to trace neurotransmission, to uncover the mechanisms of drug action, and to monitor brain activity in real time. Psychiatry has increasingly embraced the neurosciences in studies of learning and memory, sleep and dreaming, and behavioral genetics. There has been cross-fertilization with different fields - among them pharmacology, physiology, biochemistry, and experimental and developmental psychology - and many terms from those disciplines have been incorporated into the Dictionary. This edition reflects achievements not only in the basic sciences but also in their practical application. Studies of different forms and combinationss of treatments continue to refine and individualize approaches to the particular patient. To make all os this meaningful to mental health professionals and to those outside that field who are interested in what psychiatry is doing to meet the needs of its patients, the editor has retained the encyclopdic approach to the definition of many terms. That, plus the liberal use of cross-references between entries, should make it easier for the reader to access the information that is sought.