Role of the insular cortex in interpersonal attachment

Maternal and romantic attachment have been shown to recruit a distinct network of limbic regions including the insular cortex, which has extensive anatomical and functional connections to other brain regions. In order to further characterize the involvement of the insula in interpersonal attachment, we investigated attachment-induced changes in functional connectivity between the insula and the rest of the brain. Participants (n = 36) underwent an fMRI scan while passively viewing photographs of loved individuals (their own child or romantic partner; love condition) or another acquainted person. K-means clustering based on time-series correlations between insular voxels and all other brain voxels was used to identify subdivisions of the insula. The clustering produced three subregions in each hemisphere that were left-right symmetric. These subregions were then used as seeds in a psychophysiological interaction (PPI) analysis, which characterizes condition-specific changes in functional connectivity between seed regions and other brain regions. The analyses revealed increased connectivity during the love condition between the insula and regions within the ventral attention network (VAN), including the temporoparietal junction and inferior frontal gyrus, and areas in the dorsal attention network (DAN), including the intraparietal sulcus and middle frontal gyrus. Increased connectivity was also shown in the striatum and inferior temporal cortex. Decreased insular connectivity during the love condition was observed in sensorimotor areas and within default mode network (DMN) regions including the posterior cingulate cortex and precuneus. These connectivity patterns were highly similar for corresponding subdivisions of the left and right insula. These preliminary results suggest that attachment may be mediated by increased communication between the insula and the VAN, which is important for detecting behaviorally-relevant stimuli, and the DAN, which is involved in internal goal-directed attention