Cholecystokinin (CCK) is found in high concentrations in mammalian brain where it appears to act as a neurotransmitter. CCK has been implicated in a number of important physiological processes and disease states, including feeding and feeding disorders, nociception, schizophrenia, movement disorders, anxiety, and panic disorder. The recent increase in interest in CCK is mainly attributable to the development of potent selective CCK receptor antagonists. These drugs have proved to be valuable research tools and may also prove useful as therapeutic agents. This volume reviews the most recent data on the role of CCK in normal and abnormal brain function. It brings together contributors from the leading researchers in the field of CCK neurobiology. Particular emphasis is placed on the roles of CCK receptor subtypes (CCK-A and CCK-E) which have been determined using selective antagonists.