Adaptive control for insect leg position: controller properties depend on substrate compliance

This paper concentrates on the system that controls the femur-tibia joint in the legs of the stick insect, Carausius morosus. Earlier investigations have shown that this joint is subject to a mixture of proportional and differential control whereby the differential part plays a prominent role. Exper...

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Bibliographic Details
Published in:Journal of Comparative Physiology 2004-12, Vol.190 (12), p.983-991
Main Authors: Cruse, H, Kuhn, S, Park, S, Schmitz, J
Format: Article
Language:English
Subjects:
Animals
Behavior, Animal
Compliance
Denervation - methods
Electromyography - methods
Electrophysiology - methods
Female
Hindlimb - anatomy & histology
Hindlimb - innervation
Hindlimb - physiology
Insecta - physiology
Joints - physiology
Movement - physiology
Muscles - physiology
Physical Stimulation - methods
Proprioception - physiology
Reaction Time - physiology
Video Recording - methods
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Summary:This paper concentrates on the system that controls the femur-tibia joint in the legs of the stick insect, Carausius morosus. Earlier investigations have shown that this joint is subject to a mixture of proportional and differential control whereby the differential part plays a prominent role. Experiments presented here suggest another interpretation: single legs of a stick insect were systematically perturbed using devices of different compliance and compensatory forces and movements monitored. When the compliance is high (soft spring), forces are generated that return the leg close to its original position. When the compliance is low (stiff spring), larger forces are generated but sustained changes in position occur that are proportional to the force that is applied. Selective ablation of leg sense organs showed that the leg did not maintain its position after elimination of afferents of the femoral chordotonal organ. Ablation of leg campaniform sensilla had no effect. These data support the idea that different control strategies are used, depending upon substrate compliance. In particular, what we and other authors have called a differential controller, is now considered as an integral controller that "intelligently gives up" when the correlation between motor output and movement of the leg is low.
ISSN:0340-7594
1432-1351
DOI:10.1007/s00359-004-0555-y