Functional organization of hairy skin in response to sensory stimuli

Abstract

The cross correlation methods previously developed for the analysis of peripheral nerve activity in response to natural stimuli were used to study the functional organization of hairy skin. Histological methods were used to supplement these findings. Measurements of peak velocity, distribution of fiber speeds and temporal dispersion confirmed previous findings that for the myelinated fiber groups, the innervation to the caudal area of skin conducts faster than the innervation to the rostral end. From the physiological and histological data it can be concluded that the skin contains two specific mechanoreceptors. The first is to the hair, is rapid adapting and responds to movement of the hairs. These receptors are innervated by the A, alpha-beta group (high sensitivity) and the A, delta-gamma group (low sensitivity). The second type of receptor is to the skin between the hair shafts and responds to touching the skin; these receptors are not as rapidly adapting and are innervated primarily by the A, delta-gamma group. The C-fiber activity is associated with nonspecific activity in response to various mechanical stimuli. Within each sub-area there is considerable time sharing of myelinated fibers by receptors. Cutaneous sensibility consists of specific mechanoreceptors which are supplied by myelinated fibers and subserve the basic modality of touch (hair and pressure). Nonspecific activity in response to C-fiber activity subserve the sensations of pain and temperature which are not basic modalities but the result of pattern recognition of specific and non-specific activities.