The Peripheral Mechanisms of Cutaneous Sensation

Abstract

Since Adrian in 1926 first established the general principles of afferent nervous activity, there have been numerous studies of the peripheral cutaneous sensory mechanisms. Recent interest has turned on more detailed and quantitative studies of the mechanisms by which the peripheral afferent nerve fibres encode the changing conditions at the surface of the body. There are at present two principle hypotheses to account for the phenomenon. One states that the incoming information is coded in a spatial and temporal pattern of impulses in a population of afferent fibres with nerve-endings which are individually similar, if not identical, but which because of their morphological disposition may respond differently to identical stimuli. This hypothesis has been expressed in several forms by Cauna (1961), Catton (1964) and Weddell and his colleagues (Weddell 1961). The alternative classical hypothesis states that the coding, although depending in part on the temporal pattern of impulses, arises in peripheral receptors that display a considerable degree of dissimilarity, so that the receptors have played a significant part in determining or selecting the afferent fibres that are active in any particular situation.