Figure 7. Olfactory discrimination landscape.

(Top) Schematic illustration of a part of the olfactory system consisting of olfactory epithelium, cribriform and olfactory bulb, responsible for detecting different odors. The olfactory receptors shown aligned in a row are actually spread over the two-dimensional nasal cavity. The cavity, through the different receptor properties, becomes an olfactory discrimination landscape. (Bottom) Schematic illustration of the olfactory discrimination landscape demonstrating odorant recognition through a combination of surface properties and vibrational excitations. Each odorant, a point in the x, y-plane surrounded by a neighborhood, is attributed an activation domain on this landscape, as illustrated for two examples (red and green domains). Odorant deuteration corresponds to a domain-shift along the odorant vibrational excitation coordinate (blue domain).