Comparison of identified leg motoneuron structure and function between larval and adult Manduca sexta

U. Rose, R. B. Levine

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

Persistent leg motoneurons of the moth Manduca sexta were investigated in larval and adult animals to compare their dendritic structures, intrinsic electrical properties and pattern of target innervation. The study focused on two identified motoneurons of the prothoracic leg. Despite the complete remodeling of leg muscles, the motoneurons innervated pretarsal flexor muscles in both larval and adult legs. Similarly, although the central dendrites regress and regrow, the branching pattern was similar with the exception of a prominent midline branch that was not present in the adult stage. The intrinsic electrical properties of the motoneurons differed between larval and adult stages. Larval motoneurons had significantly higher membrane input resistances and more depolarized resting membrane potentials than did motoneurons in pharate adults or adults. In all stages, one motoneuron had a low maximal firing frequency, whereas the second motoneuron, which innervated the other half of the muscle, had a high maximum firing frequency. Although the two motoneurons continued to innervate the same halves of the target muscle, their relative effects on muscular contraction were reversed during metamorphosis along with concomitant changes in intrinsic properties. Pre-tarsal flexor motoneurons in pharate adults (just prior to emergence) displayed properties similar to those in emerged adults.

Original languageEnglish (US)
Pages (from-to)327-336
Number of pages10
JournalJournal of Comparative Physiology - A Sensory, Neural, and Behavioral Physiology
Volume186
Issue number4
DOIs
StatePublished - Apr 2000

Keywords

  • Behavior
  • Insect
  • Metamorphosis
  • Motoneuron
  • Properties

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Physiology
  • Animal Science and Zoology
  • Behavioral Neuroscience

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