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Proc Biol Sci. 2017 Dec 13;284(1868). pii: 20171755. doi: 10.1098/rspb.2017.1755.

A load-based mechanism for inter-leg coordination in insects.

Author information

1
Department of Biological Cybernetics, Faculty of Biology, Bielefeld University, Bielefeld, 33615, Germany cdallmann@uni-bielefeld.de.
2
Cognitive Interaction Technology Center of Excellence, Bielefeld University, Bielefeld, 33615, Germany.
3
Department of Biological Cybernetics, Faculty of Biology, Bielefeld University, Bielefeld, 33615, Germany.
4
Department of Biological Cybernetics, Faculty of Biology, Bielefeld University, Bielefeld, 33615, Germany josef.schmitz@uni-bielefeld.de.

Abstract

Animals rely on an adaptive coordination of legs during walking. However, which specific mechanisms underlie coordination during natural locomotion remains largely unknown. One hypothesis is that legs can be coordinated mechanically based on a transfer of body load from one leg to another. To test this hypothesis, we simultaneously recorded leg kinematics, ground reaction forces and muscle activity in freely walking stick insects (Carausius morosus). Based on torque calculations, we show that load sensors (campaniform sensilla) at the proximal leg joints are well suited to encode the unloading of the leg in individual steps. The unloading coincides with a switch from stance to swing muscle activity, consistent with a load reflex promoting the stance-to-swing transition. Moreover, a mechanical simulation reveals that the unloading can be ascribed to the loading of a specific neighbouring leg, making it exploitable for inter-leg coordination. We propose that mechanically mediated load-based coordination is used across insects analogously to mammals.

KEYWORDS:

campaniform sensilla; electromyography; ground reaction force; insect locomotion; motor control; stance-to-swing transition

PMID:
29187626
PMCID:
PMC5740276
DOI:
10.1098/rspb.2017.1755
[Indexed for MEDLINE]
Free PMC Article

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