Electroantennography or EAG is a technique for measuring the average output of an

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three ...

antenna to its

brain A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a ve ...

for a given odor. It is commonly used in

electrophysiology Electrophysiology (from Ancient Greek, Greek , ''ēlektron'', "amber" ee the Electron#Etymology, etymology of "electron" , ''physis'', "nature, origin"; and , ''-logy, -logia'') is the branch of physiology that studies the electrical propertie ...

while studying the function of the olfactory pathway in insects. The technique was invented in 1957 by German biologist Dietrich Schneider and shares similarities with

electro-olfactography Electro-olfactography or electroolfactography (EOG) is a type of electrography (electrophysiologic test) that aids the study of olfaction (the sense of smell). It measures and records the changing electrical potentials of the olfactory epithelium ...

.{{Citation , editor-last=Glatz , editor-first=Richard , year=2015 , title=Molecular Basis of Olfaction. Volume 130 of Progress in Molecular Biology and Translational Science , publisher=Academic Press, page=ix , url=https://books.google.com/books?id=LFOZBQAAQBAJ&pg=PR9 , isbn=978-0128029138 , postscript=.

Method

Electroantennography is usually performed either by removing an antenna from the animal and inserting two chlorided silver wires for contact onto the two ends and amplifying the voltage between them while applying an odor puff to see a deflection as in the figure, or by leaving the animal intact and inserting a ground wire (

silver Silver is a chemical element with the symbol Ag (from the Latin ', derived from the Proto-Indo-European ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical ...

silver chloride Silver chloride is a chemical compound with the chemical formula Ag Cl. This white crystalline solid is well known for its low solubility in water (this behavior being reminiscent of the chlorides of Tl+ and Pb2+). Upon illumination or heating, ...

) or a glass electrode filled with a buffer solution to some part of the body, usually inserted into an eye, and another to the tip of the antenna. A large bore glass electrode can also be placed directly over the tip of the antenna, such as in ''

Drosophila melanogaster ''Drosophila melanogaster'' is a species of fly (the taxonomic order Diptera) in the family Drosophilidae. The species is often referred to as the fruit fly or lesser fruit fly, or less commonly the " vinegar fly" or "pomace fly". Starting with ...

'' (fruit fly) antenna recordings. The latter method is useful if one is doing an experiment on the animal as a whole while doing the antennogram. Butterfly EAG

The technique is widely applied in screening of insect

pheromone A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...

s by examining the responses to fractions of a compound mixture separated using

chromatography In chemical analysis, chromatography is a laboratory technique for the separation of a mixture into its components. The mixture is dissolved in a fluid solvent (gas or liquid) called the ''mobile phase'', which carries it through a system ( ...

.Hummel, H. E. and Miller, T. A. (1984). ''Techniques in pheromone research''. Springer-Verlag, New York. Usually, the wire inserted into the antenna is a thin silver wire that is chlorided in bleach. This is an older practice. Commonly,

tungsten Tungsten, or wolfram, is a chemical element with the symbol W and atomic number 74. Tungsten is a rare metal found naturally on Earth almost exclusively as compounds with other elements. It was identified as a new element in 1781 and first isol ...

wires that have been chemically sharpened are inserted into a single neuron in the antenna. Further detailed examination of the odor response at the olfactory sensory level can be done by sensilla recording.

References

External links

Aphid Olfaction

Walter Leal Lab Home Page
Animal anatomy