Altered resting state connectivity of the insular cortex in individuals with fibromyalgia

The insular cortex (IC) and cingulate cortex (CC) are critically involved in pain perception. Previously we demonstrated that fibromyalgia (FM) patients have greater connectivity between the insula and default mode network at rest, and that changes in the degree of this connectivity were associated with changes in the intensity of ongoing clinical pain. In this study we more thoroughly evaluated the degree of resting-state connectivity to multiple regions of the IC in individuals with FM and healthy controls. We also investigated the relationship between connectivity, experimental pain, and current clinical chronic pain. Functional connectivity was assessed using resting-state functional magnetic resonance imaging in 18 FM patients and 18 age- and sex-matched healthy controls using predefined seed regions in the anterior, middle, and posterior IC. FM patients exhibited greater connectivity between 1) right mid IC and right mid/posterior CC and right mid IC, 2) right posterior IC and left CC, and 3) right anterior IC and left superior temporal gyrus. Healthy controls displayed greater connectivity between left anterior IC and bilateral medial frontal gyrus/anterior cingulate cortex; and left posterior IC and right superior frontal gyrus. Within the FM group, greater connectivity between the IC and CC was associated with decreased pressure-pain thresholds.

These data provide further support for altered resting-state connectivity between the IC and other brain regions known to participate in pain perception/modulation, which may play a pathogenic role in conditions such as FM. We speculate that altered IC connectivity is associated with the experience of chronic pain in individuals with FM.