Vibration sensitivity of slowly and rapidly adapting cutaneous mechanoreceptors in the human foot and leg.

The activities of 30 rapidly adapting cutaneous receptors (FA) and 23 slowly adapting cutaneous receptors (SA) were recorded from the lateral peroneal nerve using the microneurographic method. Their sensitivity to mechanical vibrations with constant amplitude applied at various frequencies to the center of the receptive field was studied. These two populations of cutaneous receptors were found to be very sensitive to this stimulus: they could be driven in a one to one manner up to between 100 and 200 Hz. The difference lay in the response observed when the vibration frequency was increased to above this critical value: the FA receptors sharply stopped firing, whereas the SA receptors became progressively unlinked from the stimulus. The effects of vibration on the physiological messages were also studied. The results showed that the messages coding the properties of tactile stimuli were either completely or partly masked by the receptor response to vibration. These vibration-induced modifications of cutaneous sensory messages might be at least partly responsible for the sensorimotor alterations observed when subjects are exposed to vibration.