667: Individual Neuro-Adaptability to Pain Across Cortical Motor, Sensory and Inhibitory Systems

Topic: Experimental (Non-clinical) Human Studies
Subtopic: Non -specific to any diagnosis, Electrophysiology/Clinical neurophysiology (e.g. microneurography, EEG, MEG, OPMs, TMS), Pain models (e.g. saline injection, capsaicin, UVB, HFS, incision, exercise, itch)

Background and Aims: Inter-individual differences in electrophysiological markers of adaptive neuronal responses to pain, may be related to pain processing and perception. Reduced neuro-adaptability of motor and somatosensory cortical excitability has been associated with prolonged pain and increased susceptibility to chronic pain. Multimodal electroencephalography (EEG) provides comprehensive insights into pain-related cortical excitability changes. This study integrates assessments of cortical motor, nociceptive and sensory excitability before and during tonic experimental pain, using transcranial magnetic stimulation-evoked potentials (TEPs), somatosensory-evoked potentials (SEPs), contact heat-evoked potentials (CHEPs), and auditory-evoked potentials (AEP). Integrating markers of cortical excitability may enable a more detailed characterisation of individual neuro-adaptability to pain.

Methods: In a randomized, placebo-controlled study, healthy pain-free participants (n=32) undergo multimodal electrophysiological assessments before and during tonic experimental pain induced using topical capsaicin. TEPs are elicited via primary motor cortex stimulation, SEPs via median nerve electrical stimulation, CHEPs via double thermal pain-stimulation of the hand, and AEPs by a paired-stimulus auditory paradigm. Capsaicin- and placebo-induced pain intensity is recorded every five minutes using a numerical rating scale (NRS). Associations between subjective pain responses and cortical motor, nociceptive, and sensory excitability, both before and in response to tonic experimental pain will be analysed. Data collection is currently undergoing.

Results: A feasibility-analysis based on 7 participants showed that capsaicin-induced pain NRS scores (2.1 ± 1.3, range: 1 - 6) were robust across the cortical excitability assessment period, higher than placebo NRS scores (0.0 ± 0.0, n=7). Greater pain-related changes of cortical motor, nociceptive, and sensory excitability during tonic experimental pain is hypothesised to be associated with lower perceived pain. Pain-induced changes of corticomotor excitability are expected to correlate with cortical nociceptive, sensory and auditory excitability changes, indicating coupled sensorimotor neuro-adaptability. Final statistical analyses will determine the strength and specificity of these relationships, with results to be presented at the congress.

Conclusions: Integrating cortical motor, nociceptive, and sensory excitability markers in response to pain offers a novel mechanistically informed characterisation of individual neuro-adaptability to pain. Identifying electrophysiological signatures associated with more or less adaptive neuronal responses promises a novel neuro-adaptability framework that may advance our understanding of chronic pain vulnerability, and support future stratification in pain research and prevention.

References: 1. Graven-Nielsen T. Mechanisms and manifestations in musculoskeletal pain: from experimental to clinical pain settings. Pain. 2022 Nov;163(S1):S29–45
2. Seminowicz DA, Thapa T, Schabrun SM. Corticomotor depression is associated with higher pain severity in the transition to sustained pain: a longitudinal exploratory study of individual differences. The Journal of Pain. 2019 Dec;20(12):1498–1506.
3. Jenkins LC, Chang W J, Buscemi V, Liston M, Skippen P, Cashin AG, McAuley JH, Schabrun SM. Low somatosensory cortex excitability in the acute stage of low back pain causes chronic pain. The Journal of Pain. 2022 Feb;23(2):289–304.

Presenting Author: Carolina Queiroz
Submitting Author: Carolina Queiroz

Senior Author: Thomas Graven-Nielsen

IASP 2026 Global Year theme of Neuropathic Pain: No

• Bruno Andry Couto Nascimento - Center for Neuroplasticity and Pain, Department of Health Science and Technology, Aalborg University
• Daniel Skak Mazhari-Jensen - Department of Health Science and Technology, Aalborg University
• Laura Sirucek - Center for Neuroplasticity and Pain, Department of Health Science and Technology, Aalborg University
• Jacob Sørensen - Center for Neuroplasticity and Pain, Department of Health Science and Technology, Aalborg University
• Dennis Boye Larsen - Center for Neuroplasticity and Pain, Department of Health Science and Technology, Aalborg University
• Thomas Graven-Nielsen - Center for Neuroplasticity and Pain, Department of Health Science and Technology, Aalborg University