The control of walking movements in the leg of the rock lobster

Abstract

Abstract. 1. Experiments with rock lobsters walking on a treadmill were undertaken to obtain information upon the system controlling the movement of the legs. Results show that the position of the leg is an important parameter affecting the cyclic movement of the walking leg. Stepping can be interrupted when the geometrical conditions for terminating either a return stroke or a power stroke are not fullfilled. 2. The mean value of anterior and posterior extreme positions (AEP and PEP respectively) of the walking legs do not depend on the walking speed (Fig. 1). 3. When one leg is isolated from the other walking legs by placing it on a platform the AEPs and PEPs of the other legs show a broader distribution compared to controls (Figs. 2 and 3). 4. Force measurements (Fig. 4) are in agreement with the hypothesis that the movement of the leg is controlled by a position servomechanism. 5. When one leg stands on a stationary force transducer this leg develops forces which oscillate with the step rhythm of the other legs (Fig. 5). 6. A posteriorly directed influence is found, by which the return stroke of a leg can be started when the anterior leg performs a backward directed movement. 7. Results are compared with those obtained from stick insects. The systems controlling the movement of the individual leg are similar in both, lobster and stick insect but the influences between the legs seem to be considerably different.

Decentralized Control of Insect Walking – a simple neural network explains a wide range of behavioral and neurophysiological results

“…In the latter case, oscillatory motor output can be observed although no pilocarpine has been applied. Interestingly, in principle corresponding results have also been observed in crustaceans (Clarac and Chasserat 1979;Cruse et al 1983), arguing for a general relevance of a controller structure as proposed here.…”

“…A preliminary experiment of this kind has been performed with the rock lobster (Jasus lalandii), but with only one leg on a force transducer (Cruse et al 1983). The leg standing on the fixed force transducer showed rhythmic, backward directed forces in-phase with stance movement of the anterior neighboring walking leg.…”

Intersegmental Coordination of Walking Movements in Stick Insects

“…With respect to inter-leg coordination, behavioral studies in which the position of individual legs of lobsters walking on a treadmill was perturbed showed that leg position influences the coordination of the remaining legs (Cruse and Müller 1986;Cruse et al 1983). Similar behavioral experiments with stick insects (Bässler 1979;Cruse 1979Cruse , 1985Cruse and Schwarze 1988;Dean and Wendler 1983;Graham 1979a,b) led to the proposition of six rules for coordination during walking (Cruse 1990;Cruse et al 1998).…”

A neuro-mechanical model of legged locomotion: single leg control

“…Often there is a degree of cocontraction between antagonistic muscle groups, while here only the strongest connections are drawn switches in control strategy is dependent upon the geometrical position of the legs at lifto and touchdown, termed the posterior extreme position (PEP) and anterior extreme position (AEP), respectively. This position dependent triggering has been found in both vertebrates and invertebrates (Grillner and Rossignol 1978;BaÈ ssler 1977;Cruse 1983;BaÈ ssler 1987). With this in mind, several sensory neurons were added to the network of which one S FW signals the hip position during¯exion and another S BK during extension (Fig.…”