QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by HEITLER, W. J. Articles by BRÄUNIG, P. Search for Related Content PubMed Articles by HEITLER, W. J. Articles by BRÄUNIG, P.

Journal of Experimental Biology 136,289-309 (1988)
Published by Company of Biologists 1988

The Role of Fast Extensor Motor Activity in the Locust Kick Reconsidered

W. J. HEITLER ¹ and P. BRÄUNIG ²

¹ The Gatty Marine Laboratory, Department of Biology and Pre-Clinical Medicine, University of St Andrews St Andrews, Fife KY16 8LB, Scotland
² Institut für Zoologie, Technische Universität Munchen Lichtenbergstrasse 4, 8046 Garching, FRG

To whom reprint requests should be addressed.

Fast extensor tibiae (FETi) activity has been implicated as a crucial element underlying the locust kick motor programme with regard to four circuits, (i) A positive feedback reflex from extensor tibiae (ETi) muscle tension helps maintain FETi spiking during co-contraction, (ii) A central connection from FETi to flexor tibiae (FITi) motor neurones helps initiate FITi spiking at the start of cocontraction, (iii) Reflex feedback from ETi tension to FITi motor neurones helps maintain the latter spiking during co-contraction after the central connection has decremented, (iv) A proprioceptive gate controlled by ETi tension ensures that FITi trigger activity does not occur until sufficient ETi tension has developed to allow an effective kick.

The hypotheses concerning these circuits have been tested in two ways. First, FETi was phasically inhibited for varying periods during co-contraction, abolishingits spikes and hence its central output, and reducing ETi tension. Second, the nerve containing the FETi axon was cut in the femur, thus partially denervating the ETi muscle, and reducing its tension without directly affecting FETi activity. In both cases, kicks were analysed to see whether the motor programme changed in accordance with the circuit model. The overall conclusion is that the model isnot correct, since considerable experimentally induced changes in FETi activity and ETi tension had no obvious effects on the motor programme. The circuits may play a supplementary role in generating the programme, but they are not crucial to it.

Key words: locust, kick, jump, proprioceptive gate

Accepted on December 29, 1987