Figure 2

Whole-brain functional connectivity with dorsal insula. (a) Whole-brain between-group difference in functional connectivity using right dorsal AI (from the conjunction map) as a seed region (left) showed stronger rAI–rIFG connectivity in the non-MDD group and stronger rAI–thalamus connectivity in the MDD group during high versus low pain anticipation (see Table 5 for details). Bar graphs indicate Fisher’s z transformations of the r values (Fz). (b) Significant negative correlation was found between the strength of functional connectivity between right dorsal AI and rIFG and subjective pain experience in the non-MDD group (red), whereby those subjects with strongest connections between rAI and rIFG during anticipation of pain provided lowest pain intensity (ρ=−0.43; P<0.05) and pain unpleasantness (ρ=−0.41; P=0.05) (not shown) rating. This relationship was not evident in the MDD group (blue) who showed nonsignificant relationship between rAI–rIFG connectivity and pain intensity (ρ=0.17; P=0.35), as well as pain unpleasantness (ρ=0.07; P=0.65) (not shown) rating. Furthermore, the between-group difference in the strengths of these correlations was significant for pain intensity (z=−2.16; P<0.05) and approached significance for pain unpleasantness (z=−1.72; P=0.08) rating.