Human posterior insula to posterior cingulate functional connectivity is related to the subjective intensity of acute pain

Background: Several studies have shown that, in the context of chronic pain, alterations in functional connectivity between the insula and default mode network (DMN) are correlated with pain intensity. However, it is unknown whether a similar relationship between insula-to-DMN connectivity and pain intensity exists in the absence of chronic pain. Our aims were 1) to assess whether insula-to-DMN connectivity changes are correlated to the intensity of ongoing acute pain in healthy subjects, and 2) provide an initial assessment of the capacity of pIns-to-PCC connectivity to differentiate between painful and non-painful states. 3T BOLD functional imaging data were obtained from 13 healthy human subjects in three conditions: rest, non-painful tactile stimulation, and capsaicin-induced pain. Results: Posterior insula to posterior cingulate (pIns-to-PCC) connectivity was significantly correlated with pain intensity. Additionally, we found that discrimination between painful and non-painful states could be achieved based on pIns-to-PCC connectivity. Conclusions: Functional connectivity alterations in healthy subjects experiencing acute ongoing pain are similar to those observed in chronic pain patients, and can be used to classify pain state. This suggests that the inclusion of the pIns and PCC regions in future fcMRI-based methods to detect ongoing pain is warranted.