Section 25
Chapter 24,197

Afferent impulses in cutaneous sensory nerves in human subjects

Hensel, H.; Boman, K.K.

Journal of Neurophysiology 23: 564-578


ISSN/ISBN: 0022-3077
PMID: 13713454
DOI: 10.1152/jn.1960.23.5.564
Accession: 024196176

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In conscious human subjects, afferent impulses were recorded from thin preparations of the superficial branch of the radial nerve, when mechanical and thermal stimuli were applied to the skin. All multi-fiber preparations showed a steady discharge at indifferent temperatures and reacted to mechanical stimulation. Seventy percent were also sensitive to cooling, whereas warming caused an inhibition of the discharge. A great number of single A fibers were found which reacted only to mechanical stimulation of hair receptors or mechanoreceptors in the non-hairy skin. The thresholds for eliciting a single impulse in a single mechanosensitive fiber were the same as those for arousing a subjective touch sensation. Four single fibers responded to mechanical stimulation as well as to cooling, the dynamic sensitivity being lower than -5 imp./sec.[degree]C. One single fiber was excited only by cooling. At constant temperatures below 38[degree]C, a steady discharge was seen, with a maximum of 12 imp./sec below 20[degree]C. Sudden cooling led to a high increase in frequency, with a dynamic sensitivity of -46 imp./sec.[degree]C, whereas warming caused a transient inhibition of the steady discharge.

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