Olfactory Receptor Neurons


Olfactory receptor neurons are the primary sensory cell in a system designed to detect and discriminate between a large and diverse array of chemical ligands called odours. The mechanisms employed for this task are a model of biological engineering.

Keywords: sensory; odour; perception; signalling

Figure 1.

Anatomy of the olfactory system. (a) Sagittal section of human head showing nasal cavity and olfactory mucosa lining the turbinates. (b) A schematic of the olfactory epithelium (OE) showing the three major cell types. Each are described in the text.

Figure 2.

Enzymes involved in the second messenger signalling cascade. AC, adenylyl cyclase; CNG channel, cyclic nucleotide gated channel; PDE, phosphodiesterase; R, odour receptor. (Full description in the text.)

Figure 3.

Three possible ways in which ORN axons could be wired to their glomerular targets in the olfactory bulb. Through gene targetting experiments (see text) it is now clear that all the ORNs expressing the same receptor send their axons to the same glomerulus even though the cells are widely distributed on the olfactory epithelium..

Figure 4.

Cellular circuitry of the olfactory bulb. e, excitatory; i, inhibitory; GR, granule cell; M, mitral cells; NA, noradrenergic input from brain regions; PG, periglomerular cell. (Full description in the text.)



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Further Reading

Axel R (1995) The molecular logic of smell. Scientific American 273: 154–159.

Buck LB (1996) Olfactory information coding. Annual Reviews of Neuroscience 19: 517–544.

Mombaerts P (1996) Targeting olfaction. Current Opinion in Neurobiology 6: 481–486.

Mori K and Yoshihara Y (1995) Molecular recognition and olfactory processing in the mammalian olfactory system. Progress in Neurobiology 45: 585–619.

Reed RR (1992) Signalling pathways in odorant detection. Neuron 8: 205–209.

Shepherd GM (1994) Discrimination of molecular signals by the olfactory receptor neuron. Neuron 13: 771–790.

Shepherd GM and Greer CA (1998) Olfactory bulb. In: Shepherd GM (ed.) The Synaptic Organization of the Brain, pp. 159–204. New York: Oxford University Press.

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How to Cite close
Firestein, Stuart J(Apr 2001) Olfactory Receptor Neurons. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1038/npg.els.0000273]