109: Neural associations of pain perception consistency across time: a longitudinal functional MRI study

Topic: Basic Science
Subtopic: Non-specific to any diagnosis (including studies in healthy animals), Assessment and Measurement of Pain/Nociception

Background and Aims: We have previously demonstrated that individuals show considerable variability in the reported intensity of a series of identical noxious thermal stimuli; some report consistently stable pain ratings, whereas others show large fluctuations in perceived intensity. Furthermore, we have shown that this variability is associated with activity changes in the dorsolateral and sensorimotor cortices [1]. This current investigation extends this work in a longitudinal design to determine whether response patterns to repeatedly applied acute thermal stimuli are retained in the same individuals across time - that is - is noxious stimulus encoding consistency a trait-like phenomena.

Methods: In 30 pain free individuals, 5 separate task-based functional magnetic resonance imaging (fMRI) scans were acquired every two weeks over eight weeks using a 3-Tesla MRI (Ingenia CX Phillips system; TR=1.5 seconds; raw voxel size = 2.0mm isotropic). Noxious stimuli were presented for 13.5 seconds, 10 times across 246 fMRI brain volumes interspersed with inter-trial-intervals. Pain rating data was collected continuously, and participants were grouped as "consistent" and "variable" pain encoders in each session. "Consistently consistent" and "consistently variable" groups were delineated, and voxel-by-voxel analyses conducted between groups over time in a full-factorial model (p<0.001; 25 contiguous voxels).

Results: Twelve participants showed consistently consistent and ten participants consistently inconsistent response patterns. These groups did not differ in age, sex, or overall average perceived pain (all p>0.05). Consistently inconsistent pain encoders, relative to consistently consistent and those who altered in consistency over time, showed increased activation within pain-evaluative cortical areas including the bilateral dorsolateral prefrontal cortices, the left inferior frontal gyrus, and right angular gyrus. Psychophysiological interaction analyses revealed pain encoding consistency over time was associated with increased connectivity between the left dorsolateral prefrontal cortex and anterior cingulate and orbitofrontal cortex (p<0.001 uncorrected), supporting my prior single-session investigation.

Conclusions: Our longitudinal investigation supports that pain variability encoding is conserved in the same individuals over time, and associated with altered activation of higher cognitive areas and connectivity changes between-cortical areas that respond to pain. That neither age, sex, or pain sensitivity interacted with this encoding is relevant, and suggests pain rating variability should be considered when designing assessments of the human pain response not captured by demography nuisance variables.

References: [1] Crawford, L., Mills, E., Meylakh, N., Macey, P. M., Macefield, V. G., & Henderson, L. A. (2023). Brain activity changes associated with pain perception variability. Cereb Cortex, 33(7), 4145-4155. doi:10.1093/cercor/bhac332

Presenting Author: Dr Lewis Crawford
Submitting Author: Lewis Crawford

Senior Author: Professor Luke Henderson

IASP 2026 Global Year theme of Neuropathic Pain: No

• Ashleigh Wake: BSci (Hons) - The University of Sydney
• Allan Peng: BSci (Hons) - The University of Sydney
• Jasmine Turton: BSci (Hons) - The University of Sydney
• Damien Boorman: PhD - The University of Sydney
• Kevin Keay: PhD - The University of Sydney
• Luke Henderson: PhD - The University of Sydney