Response properties of high-threshold cutaneous cold receptors in the primate.

Cutaneous high-threshold cold receptors (HCRs) in the monkey were identified as sensitive only to cold temperatures below 27 degrees C and not responsive to mechanical or heat noxious stimulation. Some HCRs had axons conducting in the low A-delta range while others had C fibers. The response properties of HCRs were contrasted with those of mechanothermal nociceptors, the latter believed to contribute to the sense of cold pain. HCRs with A delta fibers may contribute to the sense of innocuous cold below temperatures to which low-threshold cold receptors are maximally responsive.