Common and distinct neural representations of aversive somatic and visceral stimulation in healthy individuals

Abstract Pain is a primary driver of motivated behavior and learning. Different varieties of pain may be encoded in different brain circuits, but the neural similarities and differences across different types of pain are not well understood. Here, we examine the similarites and differences in brain processing of visceral and somatic pain, one of the most fundamental distinctions in the pain field. We analyze data from 7 fMRI studies (N = 165) and 5 types of pain and discomfort—esophageal, gastric, and rectal distension, cutaneous thermal stimulation, and vulvar pressure—to establish and validate generalizable pain representations. We first evaluate an established multivariate brain measure, the Neurologic Pain Signature (NPS), as a potential common nociceptive pain system across all pain types. Then, we develop a multivariate classifier for visceral vs. somatic pain. The NPS (1) responded robustly in 98% of participants across all types, (2) correlated with perceived intensity of visceral pain/discomfort, and (3) showed specificity to pain when compared with non-painful cognitive and affective conditions drawn from 12 additional studies (total N = 180, AUROC 0.93). Pre-defined signatures for other types of negative affect did not respond to visceral pain. The novel visceral vs. somatic classifier reliably distinguished somatic (thermal) from visceral (rectal) stimulation in both cross-validation and independent cohorts (AUROC 0.84). Other types reflected mixtures of somatic and visceral patterns. These results validate the NPS as measuring a common core nociceptive pain system across pain types, and lay a foundation for new brain-based biomarkers for particular types of pain.