Across the four striatal subregions of interest (anterior ventral striatum, posterior ventral striatum, caudate and Putamen, figure S1), the change in BP (ΔBP) attributable to the alcohol challenge [(BPplacebo - BPalcohol)/(BPplacebo )] differed markedly as a function of genotype, with AG subjects consistently showing signs of greater DA-release than AA individuals (main genotype effect: F[1,22]=9.3, p=0.006). Genotype accounted for 29.7% of the variance in response, measured as partial eta2, translating into an effect size of Cohen's f=0.65, i.e. between “moderate” – “large”. There was also a significant genotype x region interaction (F[3,66]=3.8, p=0.01); accordingly, post-hoc tests showed that the main genotype effect was predominantly driven by significant differences in the anterior and posterior ventral striatum, regions most closely associated with drug reward (Figure 1A–C). The highest response to alcohol was observed in the anterior ventral striatum of the AG group, where ΔBP was approximately 9%. This is more than half of the response seen with amphetamine 16, a drug that potently enhances synaptic DA by acting on the DA transporter. This relative potency is in agreement with direct measures obtained
