The fourteen ICNs were identified using publicly available, functionally defined ROIs (Shirer et al., 2012, Figure 1). Functional connections between nodes, defined as edges, were calculated, creating a correlation matrix between the time-series of all nodes within each network for each subject, again using in house scripts (Welsh et al., 2010). A Fisher r-to-z transformation was applied to yield z-scores for use in subsequent analyses. Connectivity strength is a global measure of connectivity calculated as the mean of all pairwise correlations between nodes within each network (Lynall et al., 2010). As motion has been shown to influence functional connectivity (Van Dijk et al., 2012), the framewise displacement (FD, (Power et al., 2012), for each subject was calculated across the entire resting state run from the image motion parameters for use as a covariate. For additional seed-based analyses, validating these networks for the ALC sample, see Supplemental Methods.
