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Forces exerted by a leg in support and propulsion can vary considerably when animals stand upon or traverse irregular terrains. We characterized the responses of the cockroach tibial campaniform sensilla, mechanoreceptors which encode force via strains produced in the exoskeleton, by applying forces to the leg at controlled magnitudes and rates. We also(More)
A major problem in sensory motor integration is to delineate how forces acting upon a leg are encoded and regulated in the control of posture and locomotion. We have studied responses of the trochanteral campaniform sensilla, the largest array of force detecting mechanoreceptors in the cockroach leg. Afferents from two groups of sensilla (Groups 3 and 4)(More)
We examined the mechanisms underlying force feedback in cockroach walking by recording sensory and motor activities in freely moving animals under varied load conditions. Tibial campaniform sensilla monitor forces in the leg via strains in the exoskeleton. A subgroup (proximal receptors) discharge in the stance phase of walking. This activity has been(More)
The ability to detect changes in load is important for effective use of a leg in posture and locomotion. While a number of limb receptors have been shown to encode increases in load, few afferents have been demonstrated to signal leg unloading, which occurs cyclically during walking and is indicative of slipping or perturbations. We applied mechanical(More)
Sense organs in the legs that detect body weight are an important component in the regulation of posture and locomotion. We tested the abilities of tibial campaniform sensilla, receptors that can monitor forces in the cockroach leg, to encode variations in body load in freely standing animals. Small magnets were attached to the thorax and currents were(More)
Responses of the tibial campaniform sensilla, receptors that encode strains in the exoskeleton, were characterized by recording sensory activities during perturbations in freely standing cockroaches. The substrate upon which the animal stood was displaced horizontally using ramp and hold stimuli at varied rates. The sensilla showed short latency responses(More)
To examine how walking patterns are adapted to changes in load, we recorded leg movements and muscle activities when cockroaches (Periplaneta americana) walked upright and on an inverted surface. Animals were videotaped to measure the hindleg femoro-tibial joint angle while myograms were taken from the tibial extensor and flexor muscles. The joint is(More)
The exoskeleton of the cockroach leg was imaged via confocal microscopy to generate digital graphic reconstructions of its three-dimensional structure. The cuticle is autofluorescent and can be visualized without staining, but is maximally imaged in aldehyde-fixed preparations viewed under krypton-argon laser illumination (yellow green (568 nm) excitation,(More)
Previous studies in insects demonstrated that leg coordination changes following complete ablation of distal limb segments. However, normal coordination was restored when small 'peg leg' prostheses were attached to leg stumps to permit substrate contact. We have adapted this paradigm to preserve appropriate leg mass and inertia by severing all nerves and(More)
The use of the locust (Schistocerca americana) hindleg in postural control was examined in animals that stood on a repeatedly swayed vertical substrate. Myograms were recorded from leg muscles and the angle of the femoro-tibial joint was monitored photographically. Two discrete strategies were observed; in compensatory reactions the hindleg was held in(More)