title: The carrot, not the stick: appetitive rather than aversive gustatory stimuli support associative olfactory learning in individually assayed Drosophila larvae.
abstract: The ability to learn is universal among animals; we investigate associative learning between odors and "tastants" in larval Drosophila melanogaster. As biologically important gustatory stimuli, like sugars, salts, or bitter substances have many behavioral functions, we investigate not only their reinforcing function, but also their response-modulating and response-releasing function. Concerning the response-releasing function, larvae are attracted by fructose and repelled by sodium chloride and quinine; also, fructose increases, but salt and quinine suppress feeding. However, none of these stimuli has a nonassociative, modulatory effect on olfactory choice behavior. Finally, only fructose but neither salt nor quinine has a reinforcing effect in associative olfactory learning. This implies that the response-releasing, response-modulating and reinforcing functions of these tastants are dissociated on the behavioral level. These results open the door to analyze how this dissociation is brought about on the cellular and molecular level; this should be facilitated by the cellular simplicity and genetic accessibility of the Drosophila larva.
authors.affiliation: Department of Genetics and Neurobiology, University of Würzburg, Biozentrum, Am Hubland, 97074, Würzburg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Hendel
authors.forename: Birgit
authors.initials: B
authors.lastname: Michels
authors.forename: Kirsa
authors.initials: K
authors.lastname: Neuser
authors.forename: Angela
authors.initials: A
authors.lastname: Schipanski
authors.forename: Karla
authors.initials: K
authors.lastname: Kaun
authors.forename: Marla B
authors.initials: MB
authors.lastname: Sokolowski
authors.forename: Frank
authors.initials: F
authors.lastname: Marohn
authors.forename: René
authors.initials: R
authors.lastname: Michel
authors.forename: Martin
authors.initials: M
authors.lastname: Heisenberg
authors.forename: Bertram
authors.initials: B
authors.lastname: Gerber
mesh_terms: D000818:Animals; D001070:Appetitive Behavior / Q000502:physiology*; D001362:Avoidance Learning / Q000502:physiology*; D001522:Behavior, Animal; D003216:Conditioning, Operant / Q000502:physiology; D004192:Discrimination, Psychological / Q000502:physiology; D004330:Drosophila; D005643:Fucose; D007814:Larva / Q000502:physiology; D009812:Odorants; D009833:Olfactory Pathways / Q000502:physiology*; D011803:Quinine; D012054:Reinforcement, Psychology; D012965:Sodium Chloride; D013268:Stimulation, Chemical; D013649:Taste / Q000502:physiology*
chemical_list: D005643:Fucose; D012965:Sodium Chloride; D011803:Quinine