The anatomical logic of smell

• Published in: Trends in neurosciences (Regular ed.) Vol. 28; no. 11; pp. 620 - 627
• Main Authors: Schoenfeld, Thomas A., Cleland, Thomas A.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-11-2005; Elsevier Science; Elsevier Sequoia S.A
• Subjects: Animals; Binding sites; Biological and medical sciences; Discrimination (Psychology) - physiology; Fundamental and applied biological sciences. Psychology; Humans; Inhalation; Neurons; Neurosciences; Nose - anatomy & histology; Odorants; Olfactory Bulb - cytology; Olfactory Bulb - physiology; Olfactory Pathways - anatomy & histology; Olfactory Pathways - physiology; Olfactory Receptor Neurons - cytology; Olfactory Receptor Neurons - physiology; Smell; Smell - physiology; Somesthesis and somesthetic pathways (proprioception, exteroception, nociception); interoception; electrolocation. Sensory receptors; Vertebrates: nervous system and sense organs; Inspiration; Central nervous system; Representation; Olfactory receptor; Binding site; Sensory receptor; Review; Encephalon; Discrimination; Neuron; Nose; Respiration; Odor; Biological receptor
• ISSN: 0166-2236; 1878-108X
• DOI: 10.1016/j.tins.2005.09.005

Olfactory receptor neurons (ORNs) expressing the same odorant receptor gene share ligand–receptor affinity profiles and converge onto common glomerular targets in the brain. The activation patterns of different ORN populations, evoked by differential binding of odorant molecular moieties, constitute the primary odor representation. However, odorants possess properties other than receptor-binding sites that can contribute to odorant discrimination. Among terrestrial vertebrates, odorant sorptiveness – volatility and water solubility – imposes physicochemical constraints on migration through the nose during inspiration. The non-uniform distributions of ORN populations along the inspiratory axis enable sorptiveness to modify odor representations by affecting the number of molecules reaching different receptors during a sniff. Animals can then modify and analyze odor representation further by the dynamic regulation of sniffing.