Journal of Comparative Physiology A

, Volume 184, Issue 2, pp 143–160

Physiological and morphological characterization of olfactory descending interneurons of the male silkworm moth, Bombyx mori

  • T. Mishima
  • R. Kanzaki
ORIGINAL PAPER

Abstract

In order to understand the neural mechanisms of pheromone-oriented walking in male silkworm moths, Bombyxmori, we have characterized olfactory responses and three-dimensional structure of two clusters (Group-I, Group-II) of descending interneurons in the brain by intracellular recording and staining with lucifer yellow. Neurons were imaged with laser-scanning confocal microscopy. Group-I and Group-II descending interneurons were classified into three morphological types, respectively. In response to the sex pheromone, bombykol, Type-A Group-I descending interneurons showed characteristic flipflopping activity. The Group-I descending interneurons had dendritic arborizations in the lateral accessory lobe and varicose profiles in the posterior-lateral part of the suboesophageal ganglion where the dendritic arborizations of a neck motor neuron (i.e., cv1 NMN) reside. Other types of Group-I descending interneurons exhibited long-lasting suppression of firing. The pheromonal responses of Group-II descending interneurons fell into two classes: brief excitation and brief inhibition. Type-A Group-II descending interneurons showing brief excitation had blebby processes in the posterior-lateral part of the suboesophageal ganglion. Type-B and Type-C Group-II descending interneurons did not have varicose profiles there. Therefore, the neck motor neuron regulating head turning, which accompanies the pheromone-oriented walking, may be controlled by these two types, flipflop and phasic excitation, of descending activity patterns.

Keywords Moth Pheromone Flipflop Descending interneuron Olfactory processing 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • T. Mishima
    • 1
  • R. Kanzaki
    • 1
  1. 1.Institute of Biological Sciences, University of Tsukuba, (PRESTO, Japan Science and Technology Corporation (JST)), 1-1-1 Tennodai, Tsukuba-Science City, Ibaraki 305-8572 Japan e-mail: kanzaki@biol.tsukuba.ac.jp Tel.: +81-298-536671; Fax: +81-298-536671JP

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