Examining Nociceptive Processing in Warmth-Insensitive Fields Public

Abstract

Chronic pain is a significant public health issue, affecting approximately 24% of the U.S. population. However, due to its subjective and complex nature, the diagnosis and treatment of chronic pain presents substantial challenges. In their work, researchers Green and Cruz identified warmth-insensitive fields (WIFs) which are regions in the skin that lack warm fibers and thus primarily rely on nociceptors for sensory perception. These WIFs offer a unique opportunity to examine pain perception in isolation from warmth receptors, as both are often activated together. Thus, this study utilized quantitative sensory testing to examine the sensory processing of WIFs in comparison to adjacent, normally-sensitive fields, specifically focusing on heat and heat pain detection thresholds. Results indicated a significant difference between the heat and heat pain detection thresholds of WIFs and adjacent fields. Furthermore, while variability in sensory response was observed within individual WIFs, no statistically significant correlations were found with demographics or external variables. These findings provide clear evidence of warmth detection through nociceptors, highlighting the complex and integrated relationship between heat and pain perception. Further research into the sensory processing of WIFs may offer valuable insights for the development of innovative and targeted chronic pain management. 

Table of Contents

Table of Contents 

Abstract……………………………………………………………………………………………1

Introduction……………………………………………………………………………………….1

Somatosensation and Thermal Perception………………………………………………..2

Neurobiology of Pain……………………………………………………………………...4

Nociplastic Pain and Fibromyalgia………………………………………………………...7

Sex Differences in Pain……………………..…………………………………………….11

Discovery of Warmth-Insensitive Fields………………………………………………….13

Thermal Grill Illusion……………………………………………………………………..15

Hypothesis and Research Question……………………………………………………………...16

Methods………………………………………………………………………………………….17

Participants………………………………………………………………………………17

Participant Questionnaires…………………………………………….………………...18

Experimental Setup………………………………………………………………………22

Data Analysis……………………………………………………………………………..26

Results……………………………………………………………………………………………27

Identification of Warmth-Insensitive Fields……………………………………………...27

Sensory Processing Within Warmth-Insensitive Fields…………………………………..27

Examining Confounding Variables……………………………………………………….28

Fibromyalgia Patients…………………………………………………………………….29

Discussion………………………………………………………………………………………..31

Thermal Perception and Nociception……………………………………………………31

Psychological Factors of Pain…………………………………………………………….36

Fibromyalgia……………………………………………………………………………...38

Limitations………………………………………………………………………………..41

Conclusion………………………………………………………………………………………..44

Figures and Tables………………………………………………………………………………..45

Figure 1 - WIF versus Adjacent Warmth Thresholds……………………………………..45

Figure 2 - Correlation of Warmth Thresholds Across WIFs and Adjacent Sites………….46

Figure 3 - WIF versus Adjacent Warmth Levels………………………………………….47

Figure 4 - Correlation of Warmth Levels Across WIFs and Adjacent Sites……………….48

Figure 5 - WIF versus Adjacent Heat Pain Thresholds…………………………...………49

Figure 6 - Correlation of Heat Pain Thresholds Across WIFs and Adjacent Sites………...50

Figure 7 - WIF Heat Detection versus WIF Heat Pain Detection…………………………51

Figure 8 - Correlation of WIF Heat Detection and WIF Pain Detection………………….52

Figure 9 - Difference between Warmth and Heat Pain Threshold in Individual WIFs…...53

Figure 10 - Correlation between Individual WIF Heat and Pain Detection………………54

Figure 11 - Average Difference Scores Based on Sex…………………………………….55

Table 1 - Results for Welch’s t-tests Conducted Across Female and Male Groups...…….56

Figure 12 - Average Difference Scores Based on Age……………………………………57

Table 2 - Pearson’s r Correlations between Individual WIF Difference Scores and Questionnaire Scores…………………………………………………………………….58

Table 3 - Questionnaire Scores of Fibromyalgia Patient 26……………………………...59

Table 4 - Questionnaire Scores of Fibromyalgia Patient 28…………………………...…60  

Table 5 - Quantitative Sensory Testing Results of Fibromyalgia Patients………………..61 

Table 6 - Potential Outcomes of Future Fibromyalgia Studies……………………….…..62

Table 7 - Potential Mechanisms of Fibromyalgia and Corresponding Treatment…….….63 

References………………………………………………………………………………………..64

Appendix A. Quantitative Sensory Testing Scripts……………………………………………….71

About this Honors Thesis

Rights statement

• Permission granted by the author to include this thesis or dissertation in this repository. All rights reserved by the author. Please contact the author for information regarding the reproduction and use of this thesis or dissertation.

School	Emory College
Department	Neuroscience and Behavioral Biology
Degree	B.S.
Submission	Honors Thesis
Language	English
Research Field	Health Sciences, Public Health
Mot-clé	Nociception Heat Pain Psychophysics Warmth-Insensitive Fields Heat Pain Temperature
Committee Chair / Thesis Advisor	Harper, Daniel, Emory University
Committee Members	Massa, Megan G., Emory University Lennard, Paul R. , Emory University

Dernière modification

Primary PDF

Thumbnail	Title	Date Uploaded	Actions
	Examining Nociceptive Processing in Warmth-Insensitive Fields ()	2025-04-09 11:38:19 -0400	Press to Select an action Download

Supplemental Files

Thumbnail	Title	Date Uploaded	Actions