The goal of this project is to study the contribution of the dual-nostril configuration in olfaction. In other mammalian sensory systems, vision and audition, the use of dual-sensors, two eyes and two ears respectively, adds dimensionality to perception. For example, inter-ocular comparisons allow for depth perception and inter-aural comparisons allows for sound source localization. We will conduct a series of psychophysical and fMRI studies aimed at elucidating the differences between the sensors and the mechanisms of bilateral signal integration. ? ? ?