Our analysis of specific a priori ROIs stems from hypotheses specific to the mesocorticolimbic reward pathway from the VTA/striatum to frontal cortex (which animal research implicates as sensitive to selection for high drinking). This approach has the additional benefit of reducing the number of comparisons. Left and right medial frontal ROIs (Figure 2) were defined to anatomically approximate the medial prefrontal (mPFC) and ventromedial prefrontal (vmPFC) regions to which the VTA and ventral striatum project (Chiba, Kayahara, & Nakano, 2001; Haber et al., 2006; Williams & Goldman-Rakic, 1998). These ROIs encompass activation from reward-associated stimuli in multiple studies (Filbey et al., 2008b; Hare et al., 2008; Kable & Glimcher, 2007; McClure et al., 2007; Myrick et al., 2008; Schott et al., 2008), including a study by our group (Bragulat et al., 2008). The ROIs defining the medial prefrontal areas have rostro-caudal extents spanning +56 mm to +36 mm in MNI space. mPFC has a superior extent of +14 mm and an inferior extent of −6 mm, while vmPFC spans −6 mm to −22 mm. Lateral extents were defined by conjoining
