Human Cutaneous Nociceptive Afferents with Unmyelinated (C), and myelinated (Aδ) fibers / 全日本鍼灸学会雑誌

ABSTRACT

Inserting a tangusten microelectrode into the peroneous nerve of the conscious human subject, the authors recorded the discharge of primary afferent C and A &delta; fibers. Most of the C fibers belonged to the polymodal group, as these were excited by both mechanical and thermal stimulations. These units responded to painful mechanical or thermal stimuli, as well as to non-painful stimuli of these modalities. These polymodal receptors were capable of responding to a wide range of stimulation intensity.<br>Only some of the A&delta; fibers responded to mechanical stimulation of a high intensity and painful thermal stimulation. These units increased their discharge to repeated heat administration showing a marked sensitization. This sensitization corresponded to the sense of increased heat experience by the human subjects who had hyperalgesia from the increasing heat. These findings indicate that these A&delta; afferent fibers transmit sensation of hyperalgesia from the hairy skin to the higher centers.