The Specificity of Afferent Cutaneous C Fibres in Mammals

Abstract

Abstract By dissecting very fine strands of cutaneous nerves in rats, dogs and cats it has been possible to record spikes from single afferent C fibres when applying different stimuli to the skin. Confirming earlier investigators, records have been obtained of the activity of C fibres which responded specifically to tactile stimulation of the skin and from C fibres which responded rather unspecifically to strong thermal changes in the skin in both directions (± 10dg C) as well as to mechanical stimulation of the skin. In addition to these fibres a new type of C fibres were found which responded specifically to warming or to cooling the skin to less than 1dg C. These specific “warm” C fibres and specific “cold” C fibres showed in general a behaviour similar to that of δ thermal fibres previously described. They did not respond to touching their receptive field. The skin of the mammals investigated thus possess specific “warm” C fibres as well as specific “cold” C fibres which are reciprocally brought in and out of action when the skin is subjected to even slight temperature changes.