In a previous study, we investigated the neural processes underlying strategy-independent cognitive modulation of acute pain (Chapin et al, J Pain 13, 2012, S50). Fifteen healthy volunteers who had shown the ability to cognitively change their pain ratings by 25% or more underwent fMRI scanning. During the scan, participants were asked to both increase and decrease their perception of pain using strategies that worked best for them. Utilizing personal strategies is important because we were interested in brain regions associated with effective cognitive pain modulation rather than regions related to specific strategies. Analysis of the obtained datasets showed that the dorsal anterior cingulate cortex (dACC) played an important role in the modulation process.

In this secondary analysis, we examined the connectivity of the dACC with several other regions determined previously with the purpose of identifying functional connections that significantly correlated with subjective pain ratings. For this, spherical regions of interest (ROI) were defined with centers situated at the activation peaks and radius equal to 3 mm. Connectivity measure between the dACC and the ROIs was first estimated, then its correlation with subjective pain rating computed. Group results were obtained using a one-sample t-test.

From the identified ROIs, only two regions showed functional connectivity to the dACC that significantly correlated with subjective pain rating across participants. The identified regions included the right insula (t = 2.25, p = 0.04) and right angular gyrus/BA 39 (t = -2.96, p = 0.01). Higher functional connectivity between the dACC and right insula was correlated with increased pain. However, higher functional connectivity between the dACC and angular gyrus was correlated with decreased pain. This finding points to the importance of these functional connections during cognitive pain modulation and could serve as potential targets for real-time fMRI neurofeedback training.