The control of antennal movements by leg proprioceptors in the rock lobster,Palinurus vulgaris

Summary The antennae of the rock lobster,Palinurus vulgaris, show systematic responses to movements of the legs on a tilting footboard. Myographic recordings in muscles of the first antennal segment have been used in an analysis of the sensory basis of these reactions. Antennal posture is modified in the experimental apparatus, although its relation to the change in loading conditions of the legs is uncertain. The motor control of the antennal equilibrium responses involves a complete reciprocation between both excitatory and inhibitory motoneurones to the antagonist muscle groups in the two antennae. Sensory inputs from single legs produce movements of both antennae, but a stronger drive ipsilaterally. Leg receptor inputs also modulate antennal resistance reflexes in a systematic manner, providing a sensitive test for the involvement of particular receptor organs in the leg. Movement at the coxo-basal leg joint is a major source of sensory input, and ablation/ stimulation experiments have established that stimulation of the CB chordotonal organ is a necessary but not sufficient condition to produce the antennal equilibrium reactions. The possibility is discussed that other receptors at the coxo-basal joint are also involved.D.M.N. was supported by a grant from The Max-Planck Institut to Professor H. Schöne.