ABSTRACT
In the rock lobster, Palinurus vulgaris, mechanical vibration applied to one point on the cuticle of the cephalothorax induced phasic sensory activity in numerous cuticular nerve branches innervating most of the carapace.
The same vibratory stimulus produced two kinds of effect on the tonic activity of the motoneurones innervating the extensor and flexor muscles of the distal joints (J2 and J3) of the antenna: a reciprocal motor effect, decreasing the extensor motoneurone activity and increasing the flexor motoneurone discharge, or a diffuse facilitatory motor effect increasing both extensor and flexor motoneurone activity.
The extensor and flexor excitatory motoneurones, like the inhibitory motoneurone common to the J2 and J3 extensor and flexor muscles, can be driven in a one-to-one manner by vibration at low frequency (5–10 Hz).
Either motor effect of cuticular stimulation can be modified by other sensory stimuli, e.g. passive movements of the uropods.
Cuticular vibration modulates the extensor and flexor resistance reflexes elicited by passive extension/flexion movements of the flagellum, the nature of this modulation depending upon which effect the vibratory stimulus alone produces.
The functional significance of the cuticular motor effects is discussed.
