Thoracic output of crayfish giant fibres - II. The segmental giant neurone

K. Fraser*, W. J. Heitler

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


The thoracic homologue of the abdominal segmental giant neurone of crayfish Pacifastacus leniusculus is identified and described. It has a small cell body located in the anterior ventro-lateral quadrant of the ganglion and a large neuropil arborization, with dendrites aligned along the tracts of the giant fibres. The SG axon exits the ganglion within the major root which innervates the leg, usually in the anterior region of this root. Within 1-2 mm of the ganglion the axon terminates in a mass of fine branches, apparently randomly located within the base of the root. The SG receives suprathreshold input from the ipsilateral MG and LG fibres through rectifying electrical synapses. It makes output to FF motor neurones, also through electrical synapses. The SG also makes output to at least one corollary discharge interneurone. The SG receives depolarizing inhibitory synaptic potentials which can prevent its activation by the GFs. Some but not all of these synaptic potentials are common to similar potentials occurring in a large leg promotor motor neurone.

Original languageEnglish
Pages (from-to)125-132
Number of pages8
JournalJournal of Comparative Physiology A
Issue number1
Publication statusPublished - Nov 1989


  • Crayfish
  • Promotor motor neurone


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