Joint Seminars in Neuroscience Series

Abstract: Nearly all peripheral sensory systems harbor organized topographical maps of sensory space - except for olfaction. Olfactory sensory neurons are thought to randomly choose 1 of ~1,100 possible odor receptors, thereby scattering receptors across broad swaths of the olfactory epithelium. Here we reveal that, contrary to this conventional model, the nose harbors a detailed, stereotyped and precise odor receptor map, making the olfactory epithelium arguably the most patterned structure in the nervous system. This map is the consequence of a coherent gene expression program that defines the spatial identity of each neuron, influences the receptor choice process, and aligns the map in the nose with the odor map in the olfactory bulb. Spatial order in the olfactory system therefore arises from a transcriptional code, one that precisely organizes the many discrete channels responsible for smell.

Here we describe this receptor map, the mechanisms underlying its ontogenesis, how it relates to the precise odor map present in the brain, and its implications for odor coding and olfactory function.