A second tactile system in the human skin with unmyelinated primary afferents

TL;DRAbstract

In man, unmyelinated afferents from the skin have been identified exclusively with pain and temperature senses on the basis of the stimuli which excite them. In other mammals, on the other hand, many C-afferents respond to light touch. This difference has lead to the suggestion that a phylogenetically old system of unmyelinated mechanoreceptors has largely faded out in the evolutionary process from mammals to man. However, a few touch sensitive C-afferents have recently been described in the human facial skin, suggesting a vestige in a specialized skin region. In the present study we have shown, with microneurography, that touch sensitive C-afferents are present in the human forearm. Their conduction velocities, thresholds to skin indentation, response characteristics to moving stimuli, and receptive field geography have been studied. The findings suggest that man, as other mammals, is equipped with a general system for cutaneous mechanoreception subserved by C-afferents, although it s

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