Journal of Neurophysiology, Vol 64, Issue 5 1502-1513, Copyright © 1990 by APS

ARTICLES

Comparison of heat and mechanical receptive fields of cutaneous C-fiber nociceptors in monkey

R. D. Treede, R. A. Meyer and J. N. Campbell
Department of Neurosurgery, School of Medicine, Johns Hopkins University, Baltimore, Maryland 21205.

1. Receptive-field properties were investigated in cutaneous C-fiber nociceptive afferents (CMH) responsive to mechanical and heat stimuli. Teased-fiber techniques were used to record from 28 CMHs that innervated the hairy skin of upper or lower limb in anesthetized monkeys. 2. The response to mechanical stimuli was studied with the use of calibrated von Frey probes. The response to heat stimuli was studied with the use of a laser thermal stimulator that provided stepped increases in skin temperature with rise times to the desired temperature near 100 ms. The size of the receptive field (RF) for mechanical stimuli was determined by use of a suprathreshold stimulus that consisted of a 0.5-mm-diam probe that exerted a 200-mN force (10 bar). The size of the heat RF was determined by use of a 49 degrees C stimulus applied to a 7.5-mm-diam area for 1 s. 3. Heat thresholds were determined with an ascending series of stimulus intensities and were found to be stable over many hours: they ranged from 37 to 46 degrees C (mean, 41.1 degrees C). Mechanical thresholds ranged from 1.3 to 7.3 bar (mean, 3.3 bar). There was no correlation between mechanical and heat thresholds. Both thresholds extended well below the corresponding psychophysical pain thresholds in the literature. This suggests that spatial and/or temporal summation of C-fiber input are important for pain induced by either stimulus modality. 4. Mechanical RF diameters ranged from 3.3 to 9.6 mm (mean, 4.7 mm); heat RF diameters ranged from punctate (less than 1 mm) to 9.5 mm (mean, 4.3 mm). There was a significant linear correlation between mechanical and heat RF sizes with a slope of one. The distance between the center of the mechanical RF and the center of the heat RF along one axis ranged from 0 to 1.1 mm (mean, 0.4 mm). These data indicate that the heat RFs coincided with the mechanical RFs. 5. Within the mechanical RF determined with the suprathreshold stimuli, all CMHs had one or more punctate areas of maximal mechanical sensitivity where mechanical threshold was lowest. Heat excitability extended greater than 2 mm beyond these mechanically sensitive spots. Because lateral transmission of the heat stimulus is small, this indicates that heat transduction occurs outside the regions of maximal mechanical sensitivity. 6. Both the threshold to heat and the response magnitude at suprathreshold intensities depended on the percentage of the RF area overlapped by the heat stimulus. This indicates that multiple transducer sites probably contribute to the total evoked response.(ABSTRACT TRUNCATED AT 400 WORDS)

This article has been cited by other articles:

				S. McMullan and B. M. Lumb Spinal dorsal horn neuronal responses to myelinated versus unmyelinated heat nociceptors and their modulation by activation of the periaqueductal grey in the rat J. Physiol., October 15, 2006; 576(2): 547 - 556. [Abstract] [Full Text] [PDF]

				M. S. Herskin, R. Muller, L. Schrader, and J. Ladewig A laser-based method to measure thermal nociception in dairy cows: Short-term repeatability and effects of power output and skin condition J Anim Sci, April 1, 2003; 81(4): 945 - 954. [Abstract] [Full Text] [PDF]

				M. Ringkamp, Y. B. Peng, G. Wu, T. V. Hartke, J. N. Campbell, and R. A. Meyer Capsaicin Responses in Heat-Sensitive and Heat-Insensitive A-Fiber Nociceptors J. Neurosci., June 15, 2001; 21(12): 4460 - 4468. [Abstract] [Full Text] [PDF]

				P. S. Khalsa, C. Zhang, and Y.-X. Qin Encoding of Location and Intensity of Noxious Indentation Into Rat Skin by Spatial Populations of Cutaneous Mechano-Nociceptors J Neurophysiol, May 1, 2000; 83(5): 3049 - 3061. [Abstract] [Full Text] [PDF]

				D. C. FOSTER, M. PALMER, and J. MARKS Effect of Vulvovaginal Estrogen on Sensorimotor Response of the Lower Genital Tract: A Randomized Controlled Trial Obstet. Gynecol., August 1, 1999; 94(2): 232 - 237. [Abstract] [Full Text] [PDF]

				Z. Ali, M. Ringkamp, T. V. Hartke, H. F. Chien, N. A. Flavahan, J. N. Campbell, and R. A. Meyer Uninjured C-Fiber Nociceptors Develop Spontaneous Activity and alpha -Adrenergic Sensitivity Following L6 Spinal Nerve Ligation in Monkey J Neurophysiol, February 1, 1999; 81(2): 455 - 466. [Abstract] [Full Text] [PDF]

				R.-D. Treede, R. A. Meyer, and J. N. Campbell Myelinated Mechanically Insensitive Afferents From Monkey Hairy Skin: Heat-Response Properties J Neurophysiol, September 1, 1998; 80(3): 1082 - 1093. [Abstract] [Full Text] [PDF]

				R. Schmidt, M. Schmelz, M. Ringkamp, H. O. Handwerker, and H. E. Torebjork Innervation Territories of Mechanically Activated C Nociceptor Units in Human Skin J Neurophysiol, November 1, 1997; 78(5): 2641 - 2648. [Abstract] [Full Text] [PDF]

				P. A. Illich and E. T. Walters Mechanosensory Neurons Innervating Aplysia Siphon Encode Noxious Stimuli and Display Nociceptive Sensitization J. Neurosci., January 1, 1997; 17(1): 459 - 469. [Abstract] [Full Text] [PDF]

				M. Kress and P. W. Reeh More sensory competence for nociceptive neurons in culture PNAS, December 24, 1996; 93(26): 14995 - 14997. [Full Text] [PDF]