title: Layered reward signalling through octopamine and dopamine in Drosophila.
abstract: Dopamine is synonymous with reward and motivation in mammals. However, only recently has dopamine been linked to motivated behaviour and rewarding reinforcement in fruitflies. Instead, octopamine has historically been considered to be the signal for reward in insects. Here we show, using temporal control of neural function in Drosophila, that only short-term appetitive memory is reinforced by octopamine. Moreover, octopamine-dependent memory formation requires signalling through dopamine neurons. Part of the octopamine signal requires the α-adrenergic-like OAMB receptor in an identified subset of mushroom-body-targeted dopamine neurons. Octopamine triggers an increase in intracellular calcium in these dopamine neurons, and their direct activation can substitute for sugar to form appetitive memory, even in flies lacking octopamine. Analysis of the β-adrenergic-like OCTβ2R receptor reveals that octopamine-dependent reinforcement also requires an interaction with dopamine neurons that control appetitive motivation. These data indicate that sweet taste engages a distributed octopamine signal that reinforces memory through discrete subsets of mushroom-body-targeted dopamine neurons. In addition, they reconcile previous findings with octopamine and dopamine and suggest that reinforcement systems in flies are more similar to mammals than previously thought.
authors.affiliation: Department of Neurobiology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, Massachusetts 01605, USA.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Burke
authors.forename: Wolf
authors.initials: W
authors.lastname: Huetteroth
authors.forename: David
authors.initials: D
authors.lastname: Owald
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Perisse
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Krashes
authors.forename: Gaurav
authors.initials: G
authors.lastname: Das
authors.forename: Daryl
authors.initials: D
authors.lastname: Gohl
authors.forename: Marion
authors.initials: M
authors.lastname: Silies
authors.forename: Sarah
authors.initials: S
authors.lastname: Certel
authors.forename: Scott
authors.initials: S
authors.lastname: Waddell
mesh_terms: D000818:Animals; D001070:Appetitive Behavior / Q000187:drug effects; D020013:Calcium Signaling / Q000187:drug effects; D003213:Conditioning, Psychological / Q000187:drug effects / Q000502:physiology; D004298:Dopamine / Q000378:metabolism* / Q000494:pharmacology; D059290:Dopaminergic Neurons / Q000187:drug effects / Q000378:metabolism; D029721:Drosophila Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D008297:Male; D008570:Memory, Short-Term / Q000187:drug effects / Q000502:physiology; D009042:Motivation / Q000187:drug effects / Q000502:physiology; D024521:Mushroom Bodies / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D009655:Octopamine / Q000378:metabolism* / Q000494:pharmacology; D017981:Receptors, Neurotransmitter / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D012201:Reward; D015398:Signal Transduction / Q000187:drug effects; D013649:Taste / Q000187:drug effects / Q000502:physiology
chemical_list: D029721:Drosophila Proteins; C480734:OAMB protein, Drosophila; D017981:Receptors, Neurotransmitter; D009655:Octopamine; D004298:Dopamine