Recording of the human electro-olfactogram.

Electro-olfactograms (EOG) are electrical potentials of the olfactory epithelium that occur in response to olfactory stimulation. The EOG represents the sum of generator potentials of olfactory receptor neurons. While this response has been used extensively in animal research, there are only a handful of papers describing the properties of the human EOG. In addition to a discussion of methodological issues related to the EOG, this review summarizes the characteristics and uses of these recordings. Among other results, EOGs have been used to provide evidence for the dominant role of the central nervous system in olfactory desensitization, for the functional characterization of the olfactory epithelium, the specific topographical distribution of olfactory receptors, or the expression of olfactory receptor neurons in response to exposure to odorants, and the characterization of certain odorants as olfactory receptor antagonists. In conclusion, in combination with nasal endoscopy and air-dilution olfactometry, the EOG is a unique part of a large array of techniques used to provide a complete picture of the processing of olfactory information in humans.