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No temporal contrast enhancement of simple decreases in noxious heat

Beck, B; Gnanasampanthan, S; Iannetti, GD; Haggard, P; (2019) No temporal contrast enhancement of simple decreases in noxious heat. Journal of Neurophysiology , 121 (5) pp. 1778-1786. 10.1152/jn.00335.2018. Green open access

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Abstract

Offset analgesia (OA) studies have found that small decreases in the intensity of a tonic noxious heat stimulus yield a disproportionately large amount of pain relief. In the classic OA paradigm, the decrease in stimulus intensity is preceded by an increase of equal size from an initial noxious level. Although the majority of researchers believe this temporal sequence of two changes is important for eliciting OA, it has also been suggested that the temporal contrast mechanism underlying OA may enhance detection of simple, isolated decreases in noxious heat. To test whether decreases in noxious heat intensity, by themselves, are perceived better than increases of comparable sizes, we used an adaptive two-interval alternative forced choice task to find perceptual thresholds for increases and decreases in radiant and contact heat. Decreases in noxious heat were more difficult to perceive than increases of comparable sizes from the same initial temperature of 45°C. In contrast, decreases and increases were perceived equally well within a common range of noxious temperatures (i.e., when increases started from 45°C and decreases started from 47°C). In another task, participants rated the pain intensity of heat stimuli that randomly and unpredictably increased, decreased, or remained constant. Ratings of unpredictable stimulus decreases also showed no evidence of perceptual enhancement. Our results demonstrate that there is no temporal contrast enhancement of simple, isolated decreases in noxious heat intensity. Combined with previous OA findings, they suggest that long-lasting noxious stimuli that follow an increase-decrease pattern may be important for eliciting the OA effect.

Type: Article
Title: No temporal contrast enhancement of simple decreases in noxious heat
Open access status: An open access version is available from UCL Discovery
DOI: 10.1152/jn.00335.2018
Publisher version: https://doi.org/10.1152/jn.00335.2018
Language: English
Additional information: Copyright © 2019 the American Physiological Society. Licensed under Creative Commons Attribution CC-BY 4.0: © the American Physiological Society.
Keywords: nociception, offset analgesia, pain psychophysics, signal detection
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > Div of Psychology and Lang Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > Div of Psychology and Lang Sciences > Institute of Cognitive Neuroscience
URI: http://discovery.ucl.ac.uk/id/eprint/10076215
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