While neuroimaging cognitive-subtraction task paradigms have been essential for delineating the acute effects of addictive drugs and the long-term consequences of use within circumscribed brain areas (e.g., Breiter et al., 1997; Stein et al., 1998; Kumari et al., 2003; Bickel et al., 2007; Diekhof et al., 2008), additional, complementary insight will most likely be obtained by considering alterations in circuit-level interactions between brain regions (Koob and Volkow, 2010). The last decade has witnessed an explosion in the study of functional connectivity using fMRI, largely because it allows for the exploration of large-scale networks and their interactions, thus moving towards a systems-level understanding of brain functioning (Bressler & Menon 2010; van den Heuvel and Hulshoff Pol, 2010). By extension, resting-state functional connectivity (rsFC) may allow for the identification of neural circuitry dysfunction underlying various neuropsychiatric disorders (Fox and Greicius, 2010). Among its advantages as a potential characterization and diagnostic tool are that: 1) identified rsFC circuit-alterations are less likely to be confounded by subtle differences in specific task-based experimental paradigms; 2) networks so identified appear to be consistent across time within
