While the preceding sections have highlighted the use of functional connectivity assessments as a tool for the characterization of addiction-related circuit alterations, other rsFC studies have just begun to consider the possibility that this approach could be used as a diagnostic tool to assess individual differences in addiction severity and, by extension, provide a biomarker for treatment efficacy. To this end, Hong and coworkers (2009) sought to identify neural circuits in cigarette smokers that were modulated as a function of: 1) acute nicotine administration, and 2) severity of nicotine addiction. Based on the hypothesis that the cingulate is an integral component of many addiction-related deficits, seven bilateral cingulate sub-regions were defined and used as seeds in separate rsFC analyses. Two distinct groups of networks were identified. The first consisted of seven cingulate-neocortical pathways that demonstrated enhanced connectivity strength in the presence (versus absence) of an acute nicotine patch (Fig 2A), including ACC, parietal and medial superior frontal regions. These and other identified circuits are consistent with those implicated in nicotine's performance-enhancing properties (Heishman et al., 2010). However, in a double
