Mammals have evolved dual olfactory systems to detect a vast number of odorants as well as pheromones, and to translate chemical information into diverse perceptions and distinct behaviors. Recent studies have shown that both the main and the accessory olfactory systems are involved in detecting both general odors and pheromones, but the distinct roles of each system in mediating different olfactory behaviors remain to be characterized. In addition, despite considerable progress in understanding odor detection, sensory transduction and information coding in both systems, neither the odor stimuli that elicit distinct olfactory behaviors nor the brain neural pathways that mediate odor-specific neural and endocrine responses have been clearly defined. This proposal will develop molecular techniques to identify odorant or pheromone receptors activated by behaviorally relevant olfactory stimuli to test the hypothesis that biologically significant olfactory stimuli are detected by distinct subsets of odorant or pheromone receptors. Identification of behaviorally-activated receptors will allow future studies to: 1) screen different odor fractions and individual odor components to reveal the identity of biologically significant olfactory stimuli, 2) dissect the relative roles of the two olfactory systems in regulating specific olfactory behaviors, and 3) characterize how signals from these receptors are routed in the brain to regulate distinct behaviors. Many olfactory behaviors are robust and stereotyped, and the neural circuits mediating these behavioral responses are largely genetically determined. Knowledge of the neuronal substrates mediating these innate behaviors will aid our understanding of normal human behavior as well as neurodevelopmental disorders such as autism, schizophrenia and drug addiction. [unreadable] [unreadable] [unreadable]