NAFE'S VASCULAR THEORY OF CUTANEOUS SENSITIVITY. The sense of touch consists of several partly independent senses [first identified by the Austrian physiologist Maximilian R. F. von Frey (18521932) in 1904]: pressure on the skin, warmth, cold, pain, vibration, movement across the skin, and stretch of the skin. These sensations (cutaneous senses) depend on several kinds of receptors in the skin; the cutaneous senses are known sometimes by the broader term soma-tosensory system. Two hypotheses (the specific terminal hypothesis and the specific tissue hypothesis) have been proposed for the thermal receptors although there is little or no direct evidence in support of either [cf., C. E. Osgood's account and evaluation of thermal sensitivity theories: the gradient theory; M. von Frey's specific receptor theory; J. P. Nafe's vascular theory; and W. Jenkins' concentration theory - states that the perception of cold intensity depends on the average concentration of active spots of encapsulated nerve endings beneath the area of the stimulated skin; in this approach, however, there are insufficient encapsulated endings to satisfy the theory, but this hypothesis stimulated much work on the primary functional sensory systems in the skin regarding the aspects of warmth, cold, pain, and touch]. The specific terminal hypothesis assumes a molecular configuration or other specific feature of the terminal membrane that governs differential responsiveness to thermal and mechanical stimuli. The specific tissue hypothesis assumes that afferent nerves are alike, essentially, but they end in non-neural tissues whose characteristics are responsible for the stimulus specificities observed in the activity of the associated axon. An example of this latter type of hypothesis is the vascular theory proposed by J. P. Nafe, and reviewed by D. R. Kenshalo, in which the smooth muscles of the cutaneous vascular system contract when cooled and relax when warmed. According to this viewpoint, the movement of the vessels initiates activity in the afferent nerves that terminate in the vessel walls. Another current theory, the quantitative theory of cutaneous sensitivity is representative of several of the so-called pattern theories of cutaneous sensory coding. This theory holds that the qualities of cutaneous sensation are partly a function of the mechanical and thermal properties of the tissue in which the sensory nerves terminate and partly a function of variations in the temporal and spatial patterns of neural discharge of those nerves. The pattern theories of somatosensory coding may require a great deal of experimental validation. However, on the basis of currently available data, it may be assumed that every different cutaneous sensation that can be discriminated is the result of a unique pattern of neural activity arriving at the points in the brain where it is interpreted. See also AL-RUTZ'S THEORY; CODING THEORIES; GATE-CONTROL THEORY; SOMESTHESIS, THEORIES OF. REFERENCES

von Frey, M. R. F. (1904). Vorlesungen uber physiologie. Berlin: Springer-Verlag.

Nafe, J. P. (1934). Pressure, pain, and temperature senses. In C. Murchison (Ed.), A handbook of general experimental psychology. Worcester, MA: Clark University Press. Jenkins, W. (1939). Nafe's vascular theory and the preponderance of evidence. American Journal of Psychology, 52, 462-465. Walshe, F. (1942). The anatomy and physiology of cutaneous sensibility: A critical review. Brain, 65, 48-112. Osgood, C. E. (1953). Method and theory in experimental psychology. New York: Oxford University Press. Kenshalo, D. R., & Nafe, J. P. (1962). A quantitative theory of feeling -1960. Psychological Review, 69, 1733.

Kenshalo, D. R. (1970). Cutaneous temperature receptors: some operating characteristics for a model. In J. Hardy (Ed.), Physiological and behavioral temperature regulation. Springfield, IL: Thomas.

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