title: Two types of local interneurons are distinguished by morphology, intrinsic membrane properties, and functional connectivity in the moth antennal lobe.
abstract: Neurons in the silkmoth antennal lobe (AL) are well characterized in terms of their morphology and odor-evoked firing activity. However, their intrinsic electrical properties including voltage-gated ionic currents and synaptic connectivity remain unclear. To address this, whole cell current- and voltage-clamp recordings were made from second-order projection neurons (PNs) and two morphological types of local interneurons (LNs) in the silkmoth AL. The two morphological types of LNs exhibited distinct physiological properties. One morphological type of LN showed a spiking response with a voltage-gated sodium channel gene expression, whereas the other type of LN was nonspiking without a voltage-gated sodium channel gene expression. Voltage-clamp experiments also revealed that both of two types of LNs as well as PNs possessed two types of voltage-gated potassium channels and calcium channels. In dual whole cell recordings of spiking LNs and PNs, activation of the PN elicited depolarization responses in the paired spiking LN, whereas activation of the spiking LN induced no substantial responses in the paired PN. However, simultaneous recording of a nonspiking LN and a PN showed that activation of the nonspiking LN induced hyperpolarization responses in the PN. We also observed bidirectional synaptic transmission via both chemical and electrical coupling in the pairs of spiking LNs. Thus our results indicate that there were two distinct types of LNs in the silkmoth AL, and their functional connectivity to PNs was substantially different. We propose distinct functional roles for these two different types of LNs in shaping odor-evoked firing activity in PNs.
authors.affiliation: Department of Advanced Interdisciplinary Studies, Graduate School of Engineering, The University of Tokyo, Meguro-ku, Tokyo, Japan; Research Center for Advanced Science and Technology, The University of Tokyo, Meguro-ku, Tokyo, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Tabuchi
authors.affiliation: Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan; and.
authors.forename: Li
authors.initials: L
authors.lastname: Dong
authors.affiliation: Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan; and.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Inoue
authors.affiliation: Research Center for Advanced Science and Technology, The University of Tokyo, Meguro-ku, Tokyo, Japan.
authors.forename: Shigehiro
authors.initials: S
authors.lastname: Namiki
authors.affiliation: Research Center for Advanced Science and Technology, The University of Tokyo, Meguro-ku, Tokyo, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Sakurai
authors.affiliation: Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan; and.
authors.forename: Kei
authors.initials: K
authors.lastname: Nakatani
authors.affiliation: Research Center for Advanced Science and Technology, The University of Tokyo, Meguro-ku, Tokyo, Japan kanzaki@rcast.u-tokyo.ac.jp.
authors.forename: Ryohei
authors.initials: R
authors.lastname: Kanzaki
mesh_terms: D000818:Animals; D012831:Bombyx / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D015220:Calcium Channels / Q000378:metabolism / Q000502:physiology; D007395:Interneurons / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D008297:Male; D008564:Membrane Potentials; D009434:Neural Pathways / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D009833:Olfactory Pathways / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D024642:Potassium Channels, Voltage-Gated / Q000378:metabolism / Q000502:physiology; D061566:Voltage-Gated Sodium Channels / Q000378:metabolism / Q000502:physiology
chemical_list: D015220:Calcium Channels; D024642:Potassium Channels, Voltage-Gated; D061566:Voltage-Gated Sodium Channels
keywords: antennal lobe; insect brain; patch-clamp recording