Odorants as Natural Reward: Behavioral Evidence and Underlying Circuitry of Odorant Attraction from Mice to Humans

Abstract

Pleasant odorants are represented in the posterior olfactory bulb (pOB) in mice. How does this hedonic information generate odor-motivated behaviors? Using optogenetics, we here report that stimulating the representation of pleasant odorants in a sensory structure, the pOB, can be rewarding, self-motivating and is accompanied by ventral tegmental area activation. To explore the underlying neural circuitry downstream of the OB, we use 3D high-resolution imaging and determine that the pOB preferentially projects to the olfactory tubercle, whose activity is increased by exposure to attractive odorants. We further show that attractive odorants act as reinforcers in dopamine-dependent place preference learning. Finally, we extend those findings to human, which exhibit place preference learning and an increase BOLD signal in the olfactory tubercle in response to attractive odorants. These data reveal that strong and persistent attractiveness induced by some odorants is due to a direct gateway from the pOB to the reward system.