C nociceptor activity in human nerve during painful and non painful skin stimulation.

摘要: Percutaneous recordings from more than one hundred single C fibres have been performed in the radial nerve of conscious human subjects. All these belong to poly-modal nociceptor group, being excited by mechanical and thermal also chemical stimulation. Conduction velocities showed a monophasic distribution with mean value 0.86 m/s (SD: 0.17). The threshold, measured von Frey hairs, varied between 2.3 13.1 g. receptive field was circular or elliptical; for 33 units axes were 6 mm 7 mm. Mechanically evoked fibre discharge even up 10 spikes/s not necessarily accompanied pain sensation. Nettle sting an irregular (maximum spikes/s) pricking burning sensation; sensation itch which sometimes reported, correlated frequency. activation irritant (paint remover) 3 spikes/s), threshold radiant heat usually lay below subject9s threshold. Increasing skin temperature produced increasing neural firing rate. spike frequency rarely exceeded two stimuli evoking strong pain. occurrence subjective response could be as well predicted th temperature. It is concluded that nociceptive input provoked correlates However, similar provided stimulation activates A beta mechanoreceptors, did produce