ABSTRACT
The olfactory system has been optimized over evolutionary time to perform an exquisite function: analyze odorant molecules by their molecular features, and synthesize holistic representations of them when presented in complex mixtures. It has been estimated that the olfactory system is able to detect approximately 10,000 odors (Axel 1995) over a large range of concentrations. However, unlike the sense of hearing or vision, this modality has been elusive to psychophysical analysis because no simple set of physical properties, such as light wavelengths for sight or sound frequency for hearing, has been found. Rather, olfaction appears to be intrinsically multidimensional. Along with the multidimensional nature of olfaction, the striking similarity of different olfactory systems across phyla (Hildebrand and Shepherd 1997) suggests that its architecture has been optimized to reflect basic properties of olfactory stimuli.
