Olfaction, the forgotten sense
Pablo Meyer Rojas, IBM
Abstract: The sense of smell has been ignored and even misbegotten since the positivist revolution of the XIX century. Indeed, studies of comparative neuroanatomy of the famous french neurophysiologist Paul Broca lead him to conjecture that in comparison with that of other animals, the human sense of smell was widely considered weak and underdeveloped. This is based in part on the fact that compared to the rest of the brain the human olfactory bulb is small. A modern look at the human olfactory bulb shows that it is quite large compared to those of rats and mice, which are supposed to possess a superior sense of smell. In fact, the number of olfactory bulb neurons across 24 mammalian species is comparatively similar to that of humans and our sense of smell is similar to that of other mammals. The last 20 years have brought remarkable advances in the science of olfaction, from the discovery of olfactory receptors to the characterization of olfactory circuits, the development of smell detectors or eNoses and the recent breakthrough regarding the predictability of odors from the structure of molecules. Still the prevailing view is that humans’ capacity to identify or characterize odors by name is poor. Paradoxically, I will discuss here that applying natural-language semantic representations allows for the accurate inference, using state-of-the-art machine learning methods and the two largest olfactory psychophysical data sets, of perceptual ratings for mono-molecular odorants over a large and potentially arbitrary set of olfactory descriptors. Combined with a molecule-to-ratings model using chemoinformatic features, our approach allows for the zero-shot learning inference of perceptual ratings for arbitrary molecules. I will further discuss how to expand these results to molecular mixtures and real-world applications.