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Communication Dans Un Congrès Année : 2019

At high speed, lizards do not anticipate terrain complexity

François Druelle
Jana Goyens
  • Fonction : Auteur

Résumé

In vertebrates, cyclical limb movement patterns are basically controlled by coupled spinal networks (i.e. central pattern generators or CPGs) rhythmically activated by a higher level drive, but potentially modulated by peripheral feedback in terms of timing and amplitude of limb movements in response to environmental cues. Recent studies of lizard locomotion have shown that they are able to negotiate complex terrains at high-speed without apparent changes of the basic motor timing of the locomotor system. Therefore, (at least some) lizards seem to be bound to the basic rhythmic pattern of the leg movements, whatever the terrain type they encounter, without monitoring and adjusting for proper foot placement as it is observed in birds and humans. We thus hypothesized that the legs are just following a rhythmic neural motor pattern and that the legs can react (almost) instantaneously (by flexing/extending the knee) to the substrate variations via active/passive reflexes. In this way, the important anticipatory neural mechanisms relying on visual control as observed in humans and birds are not needed. We examined the effects of running at different speeds over simple and complex terrains in two different species of lizards exhibiting different locomotor specializations, i.e. Podarcis muralis described as an efficient climber and Acanthodactylus boskianus described as a fast runner. We used kinematic analyses to describe the instantaneous velocity of the leg as well as the frequency. Our findings imply that lizards do not anticipate the terrain complexity to run suggesting the absence, in some respect, of anticipatory neural mechanisms.
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Dates et versions

hal-04020944 , version 1 (31-10-2023)

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  • HAL Id : hal-04020944 , version 1

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François Druelle, Jana Goyens, Peter Aerts. At high speed, lizards do not anticipate terrain complexity. Society for Experimental Biology meeting, Jul 2019, Séville, Spain. ⟨hal-04020944⟩
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