In mammals, olfactory stimuli influence various aspects of life including feeding, social behaviour, and reproduction.
We review the progress in olfactory research in the last decade.
In this era of gene-based techniques, a breakthrough in our knowledge on odorant and pheromone detection has occurred. Most importantly, a large gene family of odorant receptors expressed in the olfactory epithelium has been discovered. Subsets of receptor cells express one and only one receptor type and send their axons to a corresponding glomerulus in the olfactory bulb, giving rise to an odor-specific map in this structure. Two gene families of pheromone receptors expressed in the vomeronasal organ have also been discovered, and a role of pheromones in mammalian reproduction has been established.
Although the crucial steps in odorant binding and transduction to nerve signals have been revealed, the central processing of this sensory information is basically unknown. Moreover, whether pheromones serve a significant role in human behaviour is still an open question.