Which Parameters Control the Leg Movement of a Walking Insect?: II. The Start of the Swing Phase

Abstract

When a stick insect (Carausius morosus) walks on a treadwheel with one leg standing on a platform beside the wheel, this leg can be considered to perform a prolonged stance phase. To elicit a swing phase in this situation, both load and position must decline below definite threshold values. The swing phase can be elicited when - given a sufficiently posterior leg position - a central temporal signal initiates a small forward movement, and this is followed by a decrease of load. It is possible for signals from the next posterior leg to change the position threshold at which the swing phase can be started, but these commands do not influence the force values during the stance phase. Thus position is one parameter used for the decision to end the stance phase. But it does not serve as a signal for a position feedback mechanism controlling leg movement during the stance phase.