title: Postsynaptic odorant concentration dependent inhibition controls temporal properties of spike responses of projection neurons in the moth antennal lobe.
abstract: Although odorant concentration-response characteristics of olfactory neurons have been widely investigated in a variety of animal species, the effect of odorant concentration on neural processing at circuit level is still poorly understood. Using calcium imaging in the silkmoth (Bombyx mori) pheromone processing circuit of the antennal lobe (AL), we studied the effect of odorant concentration on second-order projection neuron (PN) responses. While PN calcium responses of dendrites showed monotonic increases with odorant concentration, calcium responses of somata showed decreased responses at higher odorant concentrations due to postsynaptic inhibition. Simultaneous calcium imaging and electrophysiology revealed that calcium responses of PN somata but not dendrites reflect spiking activity. Inhibition shortened spike response duration rather than decreasing peak instantaneous spike frequency (ISF). Local interneurons (LNs) that were specifically activated at high odorant concentrations at which PN responses were suppressed are the putative source of inhibition. Our results imply the existence of an intraglomerular mechanism that preserves time resolution in olfactory processing over a wide odorant concentration range.
authors.affiliation: Graduate School of Information Science and Technology, The University of Tokyo, Tokyo, Japan.
authors.forename: Terufumi
authors.initials: T
authors.lastname: Fujiwara
authors.affiliation: Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan.
authors.forename: Tomoki
authors.initials: T
authors.lastname: Kazawa
authors.affiliation: Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan.
authors.forename: Stephan Shuichi
authors.initials: SS
authors.lastname: Haupt
authors.affiliation: Graduate School of Information Science and Technology, The University of Tokyo, Tokyo, Japan ; Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan.
authors.forename: Ryohei
authors.initials: R
authors.lastname: Kanzaki
mesh_terms: D000818:Animals; D057506:Arthropod Antennae / Q000294:innervation*; D012831:Bombyx; D002118:Calcium / Q000378:metabolism; D008297:Male; D009415:Nerve Net / Q000378:metabolism; D009433:Neural Inhibition / Q000502:physiology*; D009812:Odorants; D066194:Olfactory Cortex / Q000166:cytology / Q000502:physiology; D009833:Olfactory Pathways / Q000502:physiology; D018034:Olfactory Receptor Neurons / Q000378:metabolism*; D018035:Receptors, Odorant / Q000378:metabolism*; D013569:Synapses / Q000378:metabolism*
chemical_list: D018035:Receptors, Odorant; D002118:Calcium