title: Central synaptic mechanisms underlie short-term olfactory habituation in Drosophila larvae.
abstract: Naive Drosophila larvae show vigorous chemotaxis toward many odorants including ethyl acetate (EA). Chemotaxis toward EA is substantially reduced after a 5-min pre-exposure to the odorant and recovers with a half-time of ∼20 min. An analogous behavioral decrement can be induced without odorant-receptor activation through channelrhodopsin-based, direct photoexcitation of odorant sensory neurons (OSNs). The neural mechanism of short-term habituation (STH) requires the (1) rutabaga adenylate cyclase; (2) transmitter release from predominantly GABAergic local interneurons (LNs); (3) GABA-A receptor function in projection neurons (PNs) that receive excitatory inputs from OSNs; and (4) NMDA-receptor function in PNs. These features of STH cannot be explained by simple sensory adaptation and, instead, point to plasticity of olfactory synapses in the antennal lobe as the underlying mechanism. Our observations suggest a model in which NMDAR-dependent depression of the OSN-PN synapse and/or NMDAR-dependent facilitation of inhibitory transmission from LNs to PNs contributes substantially to short-term habituation.
authors.affiliation: School of Genetics and Microbiology, Smurfit Institute of Genetics and Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: Aoife
authors.initials: A
authors.lastname: Larkin
authors.forename: Somdatta
authors.initials: S
authors.lastname: Karak
authors.forename: Rashi
authors.initials: R
authors.lastname: Priya
authors.forename: Abhijit
authors.initials: A
authors.lastname: Das
authors.forename: Champakali
authors.initials: C
authors.lastname: Ayyub
authors.forename: Kei
authors.initials: K
authors.lastname: Ito
authors.forename: Veronica
authors.initials: V
authors.lastname: Rodrigues
authors.forename: Mani
authors.initials: M
authors.lastname: Ramaswami
mesh_terms: D000262:Adenylyl Cyclases; D000818:Animals; D004330:Drosophila / Q000502:physiology*; D029721:Drosophila Proteins; D006185:Habituation, Psychophysiologic; D007150:Immunohistochemistry; D007814:Larva; D009473:Neuronal Plasticity / Q000502:physiology*; D009830:Olfactory Bulb / Q000166:cytology / Q000502:physiology*; D055696:Olfactory Perception / Q000502:physiology*; D018034:Olfactory Receptor Neurons / Q000502:physiology*; D013569:Synapses / Q000502:physiology*
chemical_list: D029721:Drosophila Proteins; D000262:Adenylyl Cyclases; C479926:Rut protein, Drosophila