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, restlessness and sleeping difficulties (American Psychiatric Association, 1994), it is noteworthy that enhanced rsFC and reduced deactivation in DMN regions has been observed among clinically anxious and depressed populations characterized by a propensity to perseverate on negative self-reflections (Gentili et al., 2009; Lanius et al., 2010; Zhou et al., 2010; Sheline et al., 2010, Hamilton et al., 2011). Increased DMN activity and/or maladaptive interactions with TPN regions may reflect an intermediate endophenotype associated with acute withdrawal, resulting in cognitive impairments as well as increased use-urges.
