We are conducting a coordinated program of neurophysiological, neuroanatomical, endocrinological and biochemical research on the sensory and hormonal basis of olfactory discrimination in mammals. The objectives of the research include (1) chemical identification of biologically active constituents in pheromonal secretions, (2) study of the mechanisms by which these substances affect neuroendocrine and reproductive functions, (3) characterization of the mechanisms by which changes in hormonal secretion influence the neural processing of biologically relevant stimuli, (4) specification of the anatomical and neurochemical relationships among structures of the olfactory and limbic-hypothalamic systems, and (5) examination of the functional significance of reciprocal connections among these forebrain structures.