title: Odorant concentration differentiator for intermittent olfactory signals.
abstract: Animals need to discriminate differences in spatiotemporally distributed sensory signals in terms of quality as well as quantity for generating adaptive behavior. Olfactory signals characterized by odor identity and concentration are intermittently distributed in the environment. From these intervals of stimulation, animals process odorant concentration to localize partners or food sources. Although concentration-response characteristics in olfactory neurons have traditionally been investigated using single stimulus pulses, their behavior under intermittent stimulus regimens remains largely elusive. Using the silkmoth (Bombyx mori) pheromone processing system, a simple and behaviorally well-defined model for olfaction, we investigated the neuronal representation of odorant concentration upon intermittent stimulation in the naturally occurring range. To the first stimulus in a series, the responses of antennal lobe (AL) projection neurons (PNs) showed a concentration dependence as previously shown in many olfactory systems. However, PN response amplitudes dynamically changed upon exposure to intermittent stimuli of the same odorant concentration and settled to a constant, largely concentration-independent level. As a result, PN responses emphasized odorant concentration changes rather than encoding absolute concentration in pulse trains of stimuli. Olfactory receptor neurons did not contribute to this response transformation which was due to long-lasting inhibition affecting PNs in the AL. Simulations confirmed that inhibition also provides advantages when stimuli have naturalistic properties. The primary olfactory center thus functions as an odorant concentration differentiator to efficiently detect concentration changes, thereby improving odorant source orientation over a wide concentration range.
authors.affiliation: Graduate School of Information Science and Technology, University of Tokyo, Tokyo, 113-8656, Japan.
authors.forename: Terufumi
authors.initials: T
authors.lastname: Fujiwara
authors.affiliation: Research Center for Advanced Science and Technology, University of Tokyo, Tokyo, 153-8904, Japan.
authors.forename: Tomoki
authors.initials: T
authors.lastname: Kazawa
authors.affiliation: Research Center for Advanced Science and Technology, University of Tokyo, Tokyo, 153-8904, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Sakurai
authors.affiliation: Research Center for Advanced Science and Technology, University of Tokyo, Tokyo, 153-8904, Japan, Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki, 305-8572, Japan.
authors.forename: Ryota
authors.initials: R
authors.lastname: Fukushima
authors.affiliation: Transgenic Silkworm Research Unit, National Institute of Agrobiological Sciences, Ibaraki, 305-8634, Japan, and.
authors.forename: Keiro
authors.initials: K
authors.lastname: Uchino
authors.affiliation: Research Center for Advanced Science and Technology, University of Tokyo, Tokyo, 153-8904, Japan, Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki, 305-8572, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Yamagata
authors.affiliation: Research Center for Advanced Science and Technology, University of Tokyo, Tokyo, 153-8904, Japan.
authors.forename: Shigehiro
authors.initials: S
authors.lastname: Namiki
authors.affiliation: Research Center for Advanced Science and Technology, University of Tokyo, Tokyo, 153-8904, Japan, Department of Biological Cybernetics, Faculty of Biology, Bielefeld University, 33615 Bielefeld, Germany kanzaki@rcast.u-tokyo.ac.jp stephan.haupt@uni-bielefeld.de.
authors.forename: Stephan Shuichi
authors.initials: SS
authors.lastname: Haupt
authors.affiliation: Graduate School of Information Science and Technology, University of Tokyo, Tokyo, 113-8656, Japan, Research Center for Advanced Science and Technology, University of Tokyo, Tokyo, 153-8904, Japan, kanzaki@rcast.u-tokyo.ac.jp stephan.haupt@uni-bielefeld.de.
authors.forename: Ryohei
authors.initials: R
authors.lastname: Kanzaki
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D012831:Bombyx; D004305:Dose-Response Relationship, Drug; D005233:Fatty Alcohols / Q000494:pharmacology; D005260:Female; D008297:Male; D009812:Odorants; D009833:Olfactory Pathways / Q000187:drug effects / Q000502:physiology*; D018034:Olfactory Receptor Neurons / Q000187:drug effects / Q000502:physiology*; D018035:Receptors, Odorant / Q000502:physiology*; D012903:Smell / Q000187:drug effects / Q000502:physiology*
chemical_list: D005233:Fatty Alcohols; D018035:Receptors, Odorant; C006787:bombykol
keywords: adaptation; insect; olfaction; sensory intensity