• The history of research on various neurohumors that control behavior appears to be very cyclical; each decade having a favorite chemical mediator implicated in behavioral control and in psychotropic drug action. Before 1950 the focus was on acetylcholine as an important element in brain function, mainly because of its involvement in peripheral and autonomic function. In the mid 1950's research on serotonin, stimulated by tenuous relationships to LSD, made 5-hydroxytryptamine the darling of the neurochemists and pharmacologists and the late 1950's and '60's found us in the noradrenergic craze with important links between psychotropic drug action, especially antidepressives, and noradrenergic function being established. We would now like to discuss what we believe is the new "darling of the '70's" -