The contributions of diverse sense organs to the control of leg movement by a walking insect

Summary During locomotion, stick insectsCarausius morosus, place the tarsus of the rear leg near the tarsus of the ipsilateral middle leg, whatever the position of the latter. This adjustment by the hind leg requires that it receive information on the actual position of the middle leg tarsus. It is shown by ablation experiments that such information is contributed by the following proprioceptors of the middle leg: the ventral and dorsal coxal hairplates, the coxal hair rows, the trochanteral hairplate and the femoral chordotonal organ. Additional information comes from other, as yet unidentified, sense organs. Several alternatives are considered to explain how the signals from the diverse sense organs of the subcoxal joint might be combined in computing the target position for the protracting hind leg. The experimental results support the hypothesis that the signals are added nonlinearly and that a signal deviating from the majority pattern is weighted less.Abbreviations cxHPu ventral coxal hairplate - cxHPd dorsal coxal hairplate - trHP trochanteral hairplate - HR hair row - feCO femoral chordotonal organ - AEP anterior extreme position