Component maps for the DMN, SN, LECN, and RECN, generated by FSL MELODIC from both groups combined, are displayed in Figure 1. As displayed in Figure 2, dual regression analysis showed that the OUD group had significantly weaker within-network functional connectivity relative to HC in a cluster (30 voxels; cluster peak at MNI coordinates (x=−16, y=19, z=52) mm) within the LECN (Cohen’s d=1.455, p=0.022 after FWE correction for voxels, contrasts, and the 4 networks examined). According to the Harvard-Oxford Cortical Structural Atlas (https://fsl.fmrib.ox.ac.uk/fsl/fslwiki/Atlases), this cluster was in the left superior frontal gyrus. According to the histological study of Rajkowska and Goldman-Rakic (1995), the entire cluster was within the coordinates of their broadly defined dorsolateral prefrontal cortex (dlPFC), with approximately half of the voxels in the cluster falling within their conservatively defined dlPFC [38]. The mean functional connectivity parameter estimates output from stage 2 of the Dual Regression procedure for HC and OUD are listed in Table 3. OUD functional connectivity was not greater than HC (p greater than 0.998) within the LECN. OUD and HC did not significantly differ in the within-network functional connectivity for any of the other 3 networks (p greater than 0.562).
