Learning Body-Site Specific Imagination-Induced Pain in Nine Individuals
Presented During:
Saturday, June 28, 2025: 11:30 AM - 12:45 PM
Brisbane Convention & Exhibition Centre
Room:
M1 & M2 (Mezzanine Level)
Poster No:
2045
Submission Type:
Abstract Submission
Authors:
Michael Sun1, Bogdan Petre1, Ke Bo1, Heejung Jung2, Tor Wager1
Institutions:
1Dartmouth College, Hanover, NH, 2Stanford University, Stanford, CA
First Author:
Co-Author(s):
Introduction:
Pain imagination involves mentally simulating or recalling painful experiences without actual nociceptive input. This cognitive process can influence athletic performance, physical rehabilitation, and anxiety by activating sensory pathways similar to real pain. While imagined sensations have been shown to produce somatotopic neural activity, no prior study has compared this to the somatotopy of verum pain.
Using nine subjects, this study takes a precision functional deep-phenotyping approach to compare individual-level overlap in pain- and somatotopy-relevant brain activity. It explores how brain regions like the anterior cingulate cortex, insula, and prefrontal cortex contribute to pain imagination and examines whether imagined and experienced pain share a somatotopic bodymap. This spatial mapping of body regions is essential for pain responses, but it remains unclear if imagined pain activates these maps similarly to verum pain.
Using nine subjects, this study takes a precision functional deep-phenotyping approach to compare individual-level overlap in pain- and somatotopy-relevant brain activity. It explores how brain regions like the anterior cingulate cortex, insula, and prefrontal cortex contribute to pain imagination and examines whether imagined and experienced pain share a somatotopic bodymap. This spatial mapping of body regions is essential for pain responses, but it remains unclear if imagined pain activates these maps similarly to verum pain.
Methods:
DESIGN: This study used a multiple N-of-1 within-subject design with three conditions: 1) Hot Stimulation ('hot', ~46-49°C), 2) Imagined Hot Stimulation ('imagine'), and 3) Warm Stimulation ('warm', <44°C). Each run targeted one of 8 pseudorandomized body sites (left/right face, arms, legs, chest, abdomen), with stimulation repeated 8 times and imagination 12 times per run. Body-site temperatures were calibrated individually prior to scanning.
PARTICIPANTS: Nine participants (5 male, 4 female) completed at least 40 runs across 10 sessions, with 4+ runs per session.
ANALYSIS: Pairwise forced-choice discrimination analyses (hot vs. warm, hot vs. imagine, imagine vs. warm) were conducted using 10-fold cross-validated support vector machines (SVM) for each subject. Subject-level mass univariate voxelwise analyses were aggregated into group-level parcelwise robust regression and count maps (indicating subjects with thresholded voxels per parcel).
Regional similarity across conditions was assessed via representational similarity analysis (RSA), examining run-level matrices within subjects. Precision functional mapping was performed by generating hot vs. warm SVM models for each subject x bodysite x parcel. Run-level images were correlated with these models, and Fisher's z-transformed correlation coefficients were tested for Same vs. Different bodysite and Within vs. Between subjects.
PARTICIPANTS: Nine participants (5 male, 4 female) completed at least 40 runs across 10 sessions, with 4+ runs per session.
ANALYSIS: Pairwise forced-choice discrimination analyses (hot vs. warm, hot vs. imagine, imagine vs. warm) were conducted using 10-fold cross-validated support vector machines (SVM) for each subject. Subject-level mass univariate voxelwise analyses were aggregated into group-level parcelwise robust regression and count maps (indicating subjects with thresholded voxels per parcel).
Regional similarity across conditions was assessed via representational similarity analysis (RSA), examining run-level matrices within subjects. Precision functional mapping was performed by generating hot vs. warm SVM models for each subject x bodysite x parcel. Run-level images were correlated with these models, and Fisher's z-transformed correlation coefficients were tested for Same vs. Different bodysite and Within vs. Between subjects.
Results:
Imagined hot stimulation was distinguishable from verum hot and warm stimulation. Shared brain mechanisms included the aMCC, mPFC, insula, primary/secondary somatosensory cortices, and thalamus, activated during imagined pain. Unique to imagined pain were the central amygdala and right hippocampus (CA23), involved in recollecting aversive experiences without nociceptive input.
Hot and Imagine conditions were significantly correlated within and across conditions, more so than Warm, reflecting consistent neural activation. Hot and Imagine also correlated more strongly with each other than with Warm.
These patterns were mirrored in most nociceptive pathway regions, except for the VPLM thalamus, which processes direct somatosensory input, less relevant for imagined pain.
Precision mapping with SVM revealed significant but subject-specific discrimination between hot and warm stimulation. Body site-specific activation was evident in S1, amygdala, parabrachial nucleus, thalamus, and hypothalamus, correlating with hot vs. warm specificity.
Hot and Imagine conditions were significantly correlated within and across conditions, more so than Warm, reflecting consistent neural activation. Hot and Imagine also correlated more strongly with each other than with Warm.
These patterns were mirrored in most nociceptive pathway regions, except for the VPLM thalamus, which processes direct somatosensory input, less relevant for imagined pain.
Precision mapping with SVM revealed significant but subject-specific discrimination between hot and warm stimulation. Body site-specific activation was evident in S1, amygdala, parabrachial nucleus, thalamus, and hypothalamus, correlating with hot vs. warm specificity.
·Figure 2. (Left) Forced-choice classification accuracy from two condition support-vector machine for each subject using leave-one-session-out (LOSO) cross-validation. (Middle) Count maps and t-maps fo
Conclusions:
This study demonstrates that pain imagination adopts a depictive representation, overlapping with real pain regions, while regions like the hippocampus and amygdala support the simulation process. This provides evidence that imagined and experienced pain exhibit correlated whole-brain activity and pathway-level similarity, supporting the idea of depictive representation. This study shows body site specificity in pain discrimination along the nociceptive pathway, with some regions replicating this mapping during imagined pain.
Emotion, Motivation and Social Neuroscience:
Self Processes
Higher Cognitive Functions:
Imagery 2
Modeling and Analysis Methods:
Activation (eg. BOLD task-fMRI)
Novel Imaging Acquisition Methods:
BOLD fMRI
Perception, Attention and Motor Behavior:
Perception: Pain and Visceral 1
Keywords:
NORMAL HUMAN
Pain
Perception
Somatosensory
Touch
1|2Indicates the priority used for review
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Provide references using APA citation style.
Lee, D., Jang, C., & Park, H. J. (2019). Neurofeedback learning for mental practice rather than repetitive practice improves neural pattern consistency and functional network efficiency in the subsequent mental motor execution. Neuroimage, 188, 680-693.
Kosslyn, S. M., Thompson, W. L., & Ganis, G. (2006). The case for mental imagery. Oxford University Press.
Holmes, E. A., & Mathews, A. (2005). Mental imagery and emotion: A special relationship?. Emotion, 5(4), 489.
Brooks, J. C., Zambreanu, L., Godinez, A., & Tracey, I. (2005). Somatotopic organisation of the human insula to painful heat studied with high resolution functional imaging. Neuroimage, 27(1), 201-209.