PUB - Publikationen an der Universität Bielefeld

Multi-legged locomotion requires appropriate coordination of of all legs with coincident ground contact. Whereas behaviourally derived coordination rules can adequately describe many aspects of inter-leg coordination, the neural mechanisms underlying these rules are still not entirely clear. The fact that inter-leg coordination is strongly affected by cut thoracic connectives in tethered walking insects suggests that neural information exchange among legs is important (Dean. 1989, J.Exp.Biol. 145:103). As yet, load transfer among legs can contribute to inter-leg coordination without neural information exchange among legs (Dallmann et al., 2017, Proc.R.Soc.Lond.B 284:20171755). Since load transfer among legs only works in freely walking animals, not tethered animals, we tested the hypothesis that connective lesions have less strong effects if load transfer among legs is possible. To do so, we recorded protraction/retraction angles of all legs in animals that either had one thoracic connective cut (pro-meso or meso-meta) or had undergone corresponding sham operations. Overall, our results were similar to those of Dean. In particular,, the leg anterior to the lesion started the swing phase largely independent of the step-cycle of its posterior neighbour leg. Lesioned animals tended to walk more slowly, but with increased sideward translation. Wheraes tethered walking animals can execute strong swing movements of hind leg after meso-meta lesion, freely walking animals tend to drag them along, with low-amplitude protraction/ retraction movements remaining. Other than in Dean's tethered animals, the leg posterior to a lesion showed significant shifts of the touch-down and lift-off locations in our experiments.The results indicate that necessary information for a coordinated walk, unattached of free or supported walking, were transmitted through the ipsilateral thoracic connectives.