Peripheral and central determinants of a nociceptive reaction: an approach to psychophysics in the rat.

<h4>Background</h4>The quantitative end-point for many behavioral tests of nociception is the reaction time, i.e. the time lapse between the beginning of the application of a stimulus, e.g. heat, and the evoked response. Since it is technically impossible to heat the skin instantaneously...

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Autores principales:	Jean-Michel Benoist, Ivanne Pincedé, Kay Ballantyne, Léon Plaghki, Daniel Le Bars
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2008
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/e24f8851918d4c1e8b9392142efe7cf1
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spelling	oai:doaj.org-article:e24f8851918d4c1e8b9392142efe7cf12021-11-25T06:18:45ZPeripheral and central determinants of a nociceptive reaction: an approach to psychophysics in the rat.1932-620310.1371/journal.pone.0003125https://doaj.org/article/e24f8851918d4c1e8b9392142efe7cf12008-09-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/18769624/pdf/?tool=EBIhttps://doaj.org/toc/1932-6203<h4>Background</h4>The quantitative end-point for many behavioral tests of nociception is the reaction time, i.e. the time lapse between the beginning of the application of a stimulus, e.g. heat, and the evoked response. Since it is technically impossible to heat the skin instantaneously by conventional means, the question of the significance of the reaction time to radiant heat remains open. We developed a theoretical framework, a related experimental paradigm and a model to analyze in psychophysical terms the "tail-flick" responses of rats to random variations of noxious radiant heat.<h4>Methodology/principal findings</h4>A CO(2) laser was used to avoid the drawbacks associated with standard methods of thermal stimulation. Heating of the skin was recorded with an infrared camera and was stopped by the reaction of the animal. For the first time, we define and determine two key descriptors of the behavioral response, namely the behavioral threshold (Tbeta) and the behavioral latency (Lbeta). By employing more than one site of stimulation, the paradigm allows determination of the conduction velocity of the peripheral fibers that trigger the response (V) and an estimation of the latency (Ld) of the central decision-making process. Ld (approximately 130 ms) is unaffected by ambient or skin temperature changes that affect the behavioral threshold (approximately 42.2-44.9 degrees C in the 20-30 degrees C range), behavioral latency (<500 ms), and the conduction velocity of the peripheral fibers that trigger the response (approximately 0.35-0.76 m/s in the 20-30 degrees C range). We propose a simple model that is verified experimentally and that computes the variations in the so-called "tail-flick latency" (TFL) caused by changes in either the power of the radiant heat source, the initial temperature of the skin, or the site of stimulation along the tail.<h4>Conclusions/significance</h4>This approach enables the behavioral determinations of latent psychophysical (Tbeta, Lbeta, Ld) and neurophysiological (V) variables that have been previously inaccessible with conventional methods. Such an approach satisfies the repeated requests for improving nociceptive tests and offers a potentially heuristic progress for studying nociceptive behavior on more firm physiological and psychophysical grounds. The validity of using a reaction time of a behavioral response to an increasing heat stimulus as a "pain index" is challenged. This is illustrated by the predicted temperature-dependent variations of the behavioral TFL elicited by spontaneous variations of the temperature of the tail for thermoregulation.Jean-Michel BenoistIvanne PincedéKay BallantyneLéon PlaghkiDaniel Le BarsPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 3, Iss 9, p e3125 (2008)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Jean-Michel Benoist Ivanne Pincedé Kay Ballantyne Léon Plaghki Daniel Le Bars Peripheral and central determinants of a nociceptive reaction: an approach to psychophysics in the rat.
description	<h4>Background</h4>The quantitative end-point for many behavioral tests of nociception is the reaction time, i.e. the time lapse between the beginning of the application of a stimulus, e.g. heat, and the evoked response. Since it is technically impossible to heat the skin instantaneously by conventional means, the question of the significance of the reaction time to radiant heat remains open. We developed a theoretical framework, a related experimental paradigm and a model to analyze in psychophysical terms the "tail-flick" responses of rats to random variations of noxious radiant heat.<h4>Methodology/principal findings</h4>A CO(2) laser was used to avoid the drawbacks associated with standard methods of thermal stimulation. Heating of the skin was recorded with an infrared camera and was stopped by the reaction of the animal. For the first time, we define and determine two key descriptors of the behavioral response, namely the behavioral threshold (Tbeta) and the behavioral latency (Lbeta). By employing more than one site of stimulation, the paradigm allows determination of the conduction velocity of the peripheral fibers that trigger the response (V) and an estimation of the latency (Ld) of the central decision-making process. Ld (approximately 130 ms) is unaffected by ambient or skin temperature changes that affect the behavioral threshold (approximately 42.2-44.9 degrees C in the 20-30 degrees C range), behavioral latency (<500 ms), and the conduction velocity of the peripheral fibers that trigger the response (approximately 0.35-0.76 m/s in the 20-30 degrees C range). We propose a simple model that is verified experimentally and that computes the variations in the so-called "tail-flick latency" (TFL) caused by changes in either the power of the radiant heat source, the initial temperature of the skin, or the site of stimulation along the tail.<h4>Conclusions/significance</h4>This approach enables the behavioral determinations of latent psychophysical (Tbeta, Lbeta, Ld) and neurophysiological (V) variables that have been previously inaccessible with conventional methods. Such an approach satisfies the repeated requests for improving nociceptive tests and offers a potentially heuristic progress for studying nociceptive behavior on more firm physiological and psychophysical grounds. The validity of using a reaction time of a behavioral response to an increasing heat stimulus as a "pain index" is challenged. This is illustrated by the predicted temperature-dependent variations of the behavioral TFL elicited by spontaneous variations of the temperature of the tail for thermoregulation.
format	article
author	Jean-Michel Benoist Ivanne Pincedé Kay Ballantyne Léon Plaghki Daniel Le Bars
author_facet	Jean-Michel Benoist Ivanne Pincedé Kay Ballantyne Léon Plaghki Daniel Le Bars
author_sort	Jean-Michel Benoist
title	Peripheral and central determinants of a nociceptive reaction: an approach to psychophysics in the rat.
title_short	Peripheral and central determinants of a nociceptive reaction: an approach to psychophysics in the rat.
title_full	Peripheral and central determinants of a nociceptive reaction: an approach to psychophysics in the rat.
title_fullStr	Peripheral and central determinants of a nociceptive reaction: an approach to psychophysics in the rat.
title_full_unstemmed	Peripheral and central determinants of a nociceptive reaction: an approach to psychophysics in the rat.
title_sort	peripheral and central determinants of a nociceptive reaction: an approach to psychophysics in the rat.
publisher	Public Library of Science (PLoS)
publishDate	2008
url	https://doaj.org/article/e24f8851918d4c1e8b9392142efe7cf1
work_keys_str_mv	AT jeanmichelbenoist peripheralandcentraldeterminantsofanociceptivereactionanapproachtopsychophysicsintherat AT ivannepincede peripheralandcentraldeterminantsofanociceptivereactionanapproachtopsychophysicsintherat AT kayballantyne peripheralandcentraldeterminantsofanociceptivereactionanapproachtopsychophysicsintherat AT leonplaghki peripheralandcentraldeterminantsofanociceptivereactionanapproachtopsychophysicsintherat AT daniellebars peripheralandcentraldeterminantsofanociceptivereactionanapproachtopsychophysicsintherat
_version_	1718413957691080704

Peripheral and central determinants of a nociceptive reaction: an approach to psychophysics in the rat.

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