Mapping Pain Memory Across Modalities: Distinct Spatial Representations of Recalled Visceral and Somatic Pain

Representation of pain areas offers a spatial dimension of pain perception, yet it has rarely been used in the context of visceral pain. This experimental study examined spatial patterns of acute visceral and somatic pain and their recall.

Healthy volunteers (N = 49, 30 females) underwent calibrated rectal distension (visceral pain) and cutaneous heat stimulation on the abdomen (somatic pain), and drew modality-specific pain areas on standardised body maps immediately after stimulation and one week later. Drawings were digitised and quantified, distinguishing local from referred pain, defined as pain area separated from local site. Pain intensity and unpleasantness were assessed with visual analogue scales, psychological traits and states via questionnaires.

Rectal distension induced larger and more diffuse areas than heat pain (p < 0.001). Pain areas were highly reproducible after one week (p < 0.001). Referred visceral pain was reported by 67% of participants, predominantly in the anterior abdomen, whereas somatic pain remained localised. Total pain areas were unrelated to pain intensity or unpleasantness. However, participants with referred visceral pain had higher trait anxiety (p = 0.011), while greater referred visceral pain extent was associated with higher pain intensity (p = 0.012). Bayesian analyses identified extraversion and behavioural inhibition as predictors of visceral pain area.

Visceral and somatic pain showed distinct, reliably recalled spatial representations. Visceral pain was more extensive and diffuse. Its association with personality traits suggests that spatial pain representations reflect stable, trait-like characteristics, highlighting the value of body maps as complementary tool for characterising interoceptive pain in experimental and clinical research.

Visceral pain evokes a broader and more diffuse spatial representation than somatic pain, which is reliably recalled and shaped by psychological traits. Body maps capture features such as referred pain that are not reflected by intensity ratings alone. Visceral pain was predicted by personality trait factors, while referred pain extent was linked to pain intensity. These findings support modality-specific body maps as a mechanism-informed tool for stratifying visceral interoceptive pain in research and clinical contexts.