In addition to negatively impacting attention to exogenous stimuli, increased DMN activity may give rise to the percept of drug urges, cravings, and/or ruminative thoughts about use. For example, increased cerebral blood flow to multiple regions, including some overlapping the DMN (e.g., vmPFC, hippocampus) predicts the severity of abstinence-induced smoking urges (Wang et al., 2007). Moreover, independent of withdrawal, increased activity in DMN regions such as vmPFC, PCC and (para)hippocampus is observed as a function of reactivity to drug cues and/or use-urges (Fig 5; Garavan et al., 2000; Brenhouse et al., 2008; Li and Sinha 2008; Naqvi and Bechara 2009; Weinstein et al., 2010; Goudriaan et al., 2010; Franklin et al., 2011; Wilcox et al., 2011; Langleben et al., 2008; Zhang et al., 2011). Cognitive down-regulation of cue-induced cravings is accompanied by increased activity in TPN regions (e.g., lateral and posterior-medial PFC) and concomitant decreases in reward-related and DMN regions (e.g., ventral striatum, ACC and vmPFC) (Kober et al., 2010). Finally, given the overlap between symptoms of major depressive disorder and acute nicotine withdrawal, for example, depressed mood, problems concentrating,
