Three systems of insular functional connectivity identified with cluster analysis

Abstract

Despite much research on the function of the insular cortex, few studies have investigated functional subdivisions of the insula in humans. The present study used resting-state functional connectivity magnetic resonance imaging (MRI) to parcellate the human insular lobe based on clustering of functional connectivity patterns. Connectivity maps were computed for each voxel in the insula based on resting-state functional MRI (fMRI) data and segregated using cluster analysis. We identified 3 insular subregions with distinct patterns of connectivity: a posterior region, functionally connected with primary and secondary somatomotor cortices; a dorsal anterior to middle region, connected with dorsal anterior cingulate cortex, along with other regions of a previously described control network; and a ventral anterior region, primarily connected with pregenual anterior cingulate cortex. Applying these regions to a separate task data set, we found that dorsal and ventral anterior insula responded selectively to disgusting images, while posterior insula did not. These results demonstrate that clustering of connectivity patterns can be used to subdivide cerebral cortex into anatomically and functionally meaningful subregions; the insular regions identified here should be useful in future investigations on the function of the insula.

Figure 1.

Three subregions of the right insula identified with cluster analysis. Ventral anterior insula (red), dorsal anterior to middle insula (orange), and posterior insula (yellow). Showing slices x = 36, x = −36, y = 14, z = 9. Images are in radiological convention.

Figure 2.

Functional connectivity (t-maps) of insular subregions: ventral anterior insula (vAI), dorsal anterior insula (dAI), and posterior insula (PI). Connectivity maps for left hemisphere seeds are shown on the left; maps for right hemisphere seeds are on the right.

Figure 3.

ROI analysis results. Connectivity strength (beta) between 3 insula subregions from cluster analysis (ventral anterior, vAI; dorsal anterior, dAI; and posterior, PI) and 3 spherical ROIs along middle to ACC (pregenual anterior, pACC; dorsal anterior, dACC; and middle, MCC). Error bars give standard error.

Figure 4.

Evoked BOLD response of insula subregions vAI, dAI, and PI to disgusting and neutral images.