The electroolfactogram: a review of its history and uses.

The electroolfactogram (EOG) is a negative electrical potential recorded at the surface of the olfactory epithelium of vertebrates. It represents primarily, if not exclusively, the summated generator potential in the olfactory receptor neurons (ORNs). While a number of studies suggest that secretory or inhibitory events may also contribute to the EOG, these are not well established. This review outlines (1) the cellular and physiological nature of the EOG response; (2) methodological considerations regarding odor selection and delivery, surgical preparation, response descriptions, and analysis; and (3) application of the EOG in human, fish, and insect olfaction and pheromonal responsivity. A number of technical issues associated with EOG recording are also discussed.