CUTANEOUS WARM RECEPTORS IN PRIMATES

In preparations from the saphenous nerve and the superficial branch of the radial nerve in Rhesus monkeys (Macaca mulatta), afferent impulses could be recorded during moderate warming of the skin. Single warm fibres serving the back of the hand and the foot had spot-like peripheral fields which were not excited by mechanical stimulation. Multi-fibre preparations excited by mild warming were also obtained, indicating a relatively dense distribution of warm receptors. At constant temperatures from 32° C on, single warm fibres showed a static discharge with a maximum frequency up to 20 impulses/sec in the range between 40 and 44° C. At higher temperatures the frequency decreased again, the discharge often changing from a regular sequence of impulses to an irregular type or a series of periodic bursts. Rapid warming caused an overshoot, rapid cooling a transient inhibition of the warm receptor discharge. © 1969 Springer-Verlag.