Estimation of intraepidermal fiber density by the detection rate of nociceptive laser stimuli in normal and pathological conditions

Mouraux, André; Ragé, Michaël; Bragard, Dominique; Plaghki, Léon

doi:10.1016/j.neucli.2012.05.004

Cited by 17 publications

(9 citation statements)

References 38 publications

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“…Because laser-evoked ERPs are thought to be exclusively related to the activation of AMH-II (the relatively short latency of the N2 and P2 waves is incompatible with the slow conduction velocity of unmyelinated C-fibers; Mouraux et al 2012), the observed dissociation between a marked effect of HFS on the perception elicited by laser stimulation and the lack of effect of HFS on the ERPs elicited by the same stimuli could indicate that HFS-induced thermal hyperalgesia is mediated by quickly adapting, heat-sensitive C-fibers. An involvement of C-fibers in secondary thermal hyperalgesia has also been proposed by Serra et al (2004).…”

Section: Effect Of Hfs On the Responses To Thermal Stimulimentioning

confidence: 99%

High-frequency electrical stimulation of the human skin induces heterotopical mechanical hyperalgesia, heat hyperalgesia, and enhanced responses to nonnociceptive vibrotactile input

Broeke

Mouraux

2014

Journal of Neurophysiology

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van den Broeke EN, Mouraux A. High-frequency electrical stimulation of the human skin induces heterotopical mechanical hyperalgesia, heat hyperalgesia, and enhanced responses to nonnociceptive vibrotactile input. J Neurophysiol 111: 1564 -1573, 2014. First published January 22, 2014 doi:10.1152/jn.00651.2013.-High-frequency electrical stimulation (HFS) of the human skin induces increased pain sensitivity in the surrounding unconditioned skin. The aim of the present study was to characterize the relative contribution of the different types of nociceptive and nonnociceptive afferents to the heterotopical hyperalgesia induced by HFS. In 17 healthy volunteers (9 men and 8 women), we applied HFS to the ventral forearm. The intensity of perception and event-related brain potentials (ERPs) elicited by vibrotactile stimuli exclusively activating nonnociceptive low-threshold mechanoreceptors and thermonociceptive stimuli exclusively activating heat-sensitive nociceptive afferents were recorded before and after HFS. The previously described mechanical hyperalgesia following HFS was confirmed by measuring the changes in the intensity of perception elicited by mechanical punctate stimuli. HFS increased the perceived intensity of both mechanical punctate and thermonociceptive stimuli applied to the surrounding unconditioned skin. The time course of the effect of HFS on the perception of mechanical and thermal nociceptive stimuli was similar. This indicates that HFS does not only induce mechanical hyperalgesia, but also induces heat hyperalgesia in the heterotopical area. Vibrotactile ERPs were also enhanced after HFS, indicating that nonnociceptive somatosensory input could contribute to the enhanced responses to mechanical pinprick stimuli. Finally, the magnitude of thermonociceptive ERPs was unaffected by HFS, indicating that type II A-fiber mechanoheat nociceptors, thought to be the primary contributor to these brain responses, do not significantly contribute to the observed heat hyperalgesia.high-frequency stimulation; secondary hyperalgesia; event-related potentials; mechanical; heat

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Section: Effect Of Hfs On the Responses To Thermal Stimulimentioning

confidence: 99%

High-frequency electrical stimulation of the human skin induces heterotopical mechanical hyperalgesia, heat hyperalgesia, and enhanced responses to nonnociceptive vibrotactile input

Broeke

Mouraux

2014

Journal of Neurophysiology

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“…Infrared lasers have been used in a few studies on animal behaviour [1,8,39,63], electrophysiology [14,56,58], dorsal root ganglion (DRG) neurons [19,40] and heterologously expressed TRPV1 [27,64]. Wavelengths of these lasers, however, range between 980 and 10,600 nm [19,59], spot sizes between 0.1 and 10 mm [27,41] and pulse durations between 3 and 400 ms [19,53], making comparisons across studies difficult.…”

Section: Introductionmentioning

confidence: 99%

The capsaicin receptor TRPV1 is the first line defense protecting from acute non damaging heat: a translational approach

et al. 2020

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Background: Pain is the vital sense preventing tissue damage by harmful noxious stimuli. The capsaicin receptor TRPV1 is activated by noxious temperatures, however, acute heat pain is only marginally affected in mice after TRPV1 knockout but completely eliminated in mice lacking TRPV1 positive fibers. Exploring contribution of candidate signal transduction mechanisms to heat pain in humans needs translational models. Methods: We used focused, non-damaging, short near-infrared laser heat stimuli (wavelength 1470/1475 nm) to study the involvement of TRPV1-expressing nerve fibers in the encoding of heat pain intensity. Human psychophysics (both sexes) were compared to calcium transients in native rat DRG neurons and heterologously expressing HEK293 cells. Results: Heating of dermal and epidermal nerve fibers in humans with laser stimuli of ≥ 2.5 mJ (≥ 25 ms, 100 mW) induced pain that increased linearly as a function of stimulus intensity in double logarithmic space across two orders of magnitude and was completely abolished by desensitization using topical capsaicin. In DRG neurons and TRPV1expressing HEK cells, heat sensitivity was restricted to capsaicin sensitive cells. Strength duration curves (2-10 ms range) and thresholds (DRGs 0.56 mJ, HEK cells 0.52 mJ) were nearly identical. Tachyphylaxis upon repetitive stimulation occurred in HEK cells (54%), DRGs (59%), and humans (25%). Conclusion: TRPV1-expressing nociceptors encode transient non-damaging heat pain in humans, thermal gating of TRPV1 is similar in HEK cells and DRG neurons, and TRPV1 tachyphylaxis is an important modulator of heat pain sensitivity. These findings suggest that TRPV1 expressed in dermal and epidermal populations of nociceptors serves as first line defense against heat injury.

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“…The Aδ response rate can likely be further increased by increasing the grid diameter as was demonstrated in other studies [6,7]. In this study, the theory presented by Plaghki and Mouraux [2] to determine the probability of not stimulating fibers was used to determine the probability of selective Aδ-or C-fiber activation.…”

Section: Discussionmentioning

confidence: 66%

“…The epidermal nerve fiber density of Aδ-fibers is approximately < 1/mm 2 and of C-fibers 2 -8/mm 2 [5,7,8]. When assuming that the spatial distribution of Aδ-and Cfiber receptors has a Poisson distribution with average occurrence of ρ Aδ = 0.5/mm 2 and ρC = 5/mm 2 , respectively, then, the probability that Aδ-of C-fibers are stimulated is given by Equation (1) [2].…”

Section: Differences In Epidermal Nerve Fiber Densitymentioning

confidence: 99%

Selective Laser Stimulation of Aδ- or C-Fibers Through Application of a Spatial Filter: A Study in Healthy Volunteers

et al. 2016

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Background: Pain is perceived through different pathways involving thinly myelinated Aδ-fibers and unmyelinated C-fibers. Aδ-fibers are responsible for a quick, sharp pain, whereas C-fibers relate to a lateonset, burning sensation. Several studies suggest that it is essential to investigate nociceptive fibers separately and in relation to each other. The aim of this study was to selectively stimulate Aδ-and C-fibers using a 980-nm diode laser by varying the laser settings and the stimulated surface area in healthy subjects.

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Estimation of intraepidermal fiber density by the detection rate of nociceptive laser stimuli in normal and pathological conditions

Cited by 17 publications

References 38 publications

High-frequency electrical stimulation of the human skin induces heterotopical mechanical hyperalgesia, heat hyperalgesia, and enhanced responses to nonnociceptive vibrotactile input

High-frequency electrical stimulation of the human skin induces heterotopical mechanical hyperalgesia, heat hyperalgesia, and enhanced responses to nonnociceptive vibrotactile input

The capsaicin receptor TRPV1 is the first line defense protecting from acute non damaging heat: a translational approach

Selective Laser Stimulation of Aδ- or C-Fibers Through Application of a Spatial Filter: A Study in Healthy Volunteers

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