The Stance Phase and its Control by Sensory Information During Walking in Crustacea

By definition, locomotion is a succession of steps with alternating swing and stance phases. In Crustacea, the stance phase is a slow ramp propulsive movement for which sensory control is particularly important. Spatio-temporal as well as free components can define the stance phase as opposed to the swing phase. Contact and force mechanoreceptors situated at the tip of the legs in several Decapods seemed to provide important cues to stance phase parameters. Their selective stimulation elicits a reflex which seems to be able to reset the stepping cycle. This reflex was also studied in Crayfish isolated ganglion preparations, where its role is discussed.