title: GABAergic projection neurons route selective olfactory inputs to specific higher-order neurons.
abstract: We characterize an inhibitory circuit motif in the Drosophila olfactory system, parallel inhibition, which differs from feedforward or feedback inhibition. Excitatory and GABAergic inhibitory projection neurons (ePNs and iPNs) each receive input from antennal lobe glomeruli and send parallel output to the lateral horn, a higher center implicated in regulating innate olfactory behavior. Ca(2+) imaging of specific lateral horn neurons as an olfactory readout revealed that iPNs selectively suppressed food-related odor responses, but spared signal transmission from pheromone channels. Coapplying food odorant did not affect pheromone signal transmission, suggesting that the differential effects likely result from connection specificity of iPNs, rather than a generalized inhibitory tone. Ca(2+) responses in the ePN axon terminals show no detectable suppression by iPNs, arguing against presynaptic inhibition as a primary mechanism. The parallel inhibition motif may provide specificity in inhibition to funnel specific olfactory information, such as food and pheromone, into distinct downstream circuits.
authors.affiliation: Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA; Department of Applied Physics, Stanford University, Stanford, CA 94305, USA.
authors.forename: Liang
authors.initials: L
authors.lastname: Liang
authors.forename: Yulong
authors.initials: Y
authors.lastname: Li
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Potter
authors.forename: Ofer
authors.initials: O
authors.lastname: Yizhar
authors.forename: Karl
authors.initials: K
authors.lastname: Deisseroth
authors.forename: Richard W
authors.initials: RW
authors.lastname: Tsien
authors.forename: Liqun
authors.initials: L
authors.lastname: Luo
mesh_terms: D000818:Animals; D001921:Brain / Q000502:physiology*; D004330:Drosophila; D059330:GABAergic Neurons / Q000502:physiology*; D009433:Neural Inhibition / Q000502:physiology*; D019581:Neuropil / Q000502:physiology*; D009833:Olfactory Pathways / Q000502:physiology*; D018034:Olfactory Receptor Neurons / Q000502:physiology; D010675:Pheromones; D017729:Presynaptic Terminals / Q000502:physiology; D012903:Smell / Q000502:physiology*
chemical_list: D010675:Pheromones