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Dynamic Quantitative Sensory Testing to Characterize Central Pain Processing
Published on: February 16, 2017
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Conditioned pain modulation dampens the thermal grill illusion.
D E Harper1,2, M Hollins1
1Department of Psychology and Neuroscience, University of North Carolina at Chapel Hill, USA.
European Journal of Pain (London, England)
|June 3, 2017
Summary
Conditioned pain modulation (CPM) equally reduces the perceived heat and pain of the thermal grill illusion and noxious heat. This suggests nociceptive signals contribute to thermal intensity perception.
Area of Science:
- Neuroscience
- Pain Perception
- Sensory Science
Background:
- The thermal grill illusion (TGI) is the perception of burning heat and pain from simultaneous innocuous warm and cool stimuli.
- The role of ascending nociceptive signals in generating the TGI is debated.
- Conditioned pain modulation (CPM) is a top-down pain inhibitory mechanism.
Purpose of the Study:
- To investigate the neural mechanisms of the TGI using CPM.
- To determine if CPM affects TGI-induced pain similarly to noxious heat pain.
Main Methods:
- Subjects underwent a CPM run by immersing their left hand in cold water before thermal grill stimulation.
- Pain and unpleasantness ratings were compared between CPM and control runs.
- An experimental group rated TGI pain, while a control group rated noxious heat pain.
Main Results:
- CPM significantly reduced pain, unpleasantness, and perceived heat for both noxious heat and the TGI.
- The reduction in pain and unpleasantness was comparable for both noxious heat and the TGI.
- Perceived thermal sensation shifted from 'hot' to 'warm' for both conditions under CPM.
Conclusions:
- The TGI likely involves nociceptive signals processed by dorsal horn convergent neurons.
- CPM's descending inhibition selectively targets these neurons, reducing TGI perception.
- Nociceptive signals contribute to the perceived thermal intensity of cutaneous stimuli.
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