Electroantennogram Assays: Rapid and Convenient Screening Procedures for Pheromones

Abstract

Although odor perception in general is poorly understood, the insect’s peripheral sensing system-the antenna-is easily accessible and has been studied in great detail (Steinbrecht and Schneider, 1980;Kaissling and Thorson, 1980;Kaissling, 1971). Schneider (1957) pioneered the electroantennogram (EAG) technique and carried out the first electrophysiological experiments on olfaction in insects with Bombyx mori. Studies with B. mori revealed that slow olfactory receptor potentials could be recorded from an isolated antenna positioned between two glass capillary microelectrodes connected to an amplifier and a recording instrument. Schneider (1963) suggested that the “EAG is essentially the sum of many olfactory receptor potentials recorded more or less simultaneously by an electrode located in the sensory epithelium.” He interpreted (Schneider, 1969) the negative potential of these slow electrical reactions of dendrites in the olfactory cells as a receptor membrane depolarization. The amplitude of the response, which correlates to the frequency of generated nerve impulses, was found to increase with increasing concentrations of the chemical stimulus until a saturation level was reached.