title: A single population of olfactory sensory neurons mediates an innate avoidance behaviour in Drosophila.
abstract: All animals exhibit innate behaviours in response to specific sensory stimuli that are likely to result from the activation of developmentally programmed neural circuits. Here we observe that Drosophila exhibit robust avoidance to odours released by stressed flies. Gas chromatography and mass spectrometry identifies one component of this 'Drosophila stress odorant (dSO)' as CO2. CO2 elicits avoidance behaviour, at levels as low as 0.1%. We used two-photon imaging with the Ca2+-sensitive fluorescent protein G-CaMP to map the primary sensory neurons governing avoidance to CO2. CO2 activates only a single glomerulus in the antennal lobe, the V glomerulus; moreover, this glomerulus is not activated by any of 26 other odorants tested. Inhibition of synaptic transmission in sensory neurons that innervate the V glomerulus, using a temperature-sensitive Shibire gene (Shi(ts)), blocks the avoidance response to CO2. Inhibition of synaptic release in the vast majority of other olfactory receptor neurons has no effect on this behaviour. These data demonstrate that the activation of a single population of sensory neurons innervating one glomerulus is responsible for an innate avoidance behaviour in Drosophila.
authors.affiliation: Howard Hughes Medical Institute, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Greg S B
authors.initials: GS
authors.lastname: Suh
authors.forename: Allan M
authors.initials: AM
authors.lastname: Wong
authors.forename: Anne C
authors.initials: AC
authors.lastname: Hergarden
authors.forename: Jing W
authors.initials: JW
authors.lastname: Wang
authors.forename: Anne F
authors.initials: AF
authors.lastname: Simon
authors.forename: Seymour
authors.initials: S
authors.lastname: Benzer
authors.forename: Richard
authors.initials: R
authors.lastname: Axel
authors.forename: David J
authors.initials: DJ
authors.lastname: Anderson
mesh_terms: D000388:Air / Q000032:analysis; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects / Q000502:physiology*; D001921:Brain / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D002118:Calcium / Q000378:metabolism; D002245:Carbon Dioxide / Q000032:analysis / Q000494:pharmacology; D004331:Drosophila melanogaster / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D006918:Hydroxyurea / Q000494:pharmacology; D007323:Instinct; D051379:Mice; D009812:Odorants / Q000032:analysis; D018034:Olfactory Receptor Neurons / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D013312:Stress, Physiological / Q000503:physiopathology
chemical_list: D002245:Carbon Dioxide; D002118:Calcium; D006918:Hydroxyurea