The most informative regions for the classification and prediction also included the right NACC. As part of the reward system, the NACC plays an important role in processing rewarding, reinforcing stimuli (such as alcohol) [58]. Alcohol consumption has rewarding properties in both animals and humans driven by enhanced dopamine and opioid transmission in the basal ganglia [67]. Human imaging studies of acute alcohol administration demonstrated that intravenous alcohol increased dopamine release in the right NACC [68, 69]. In addition, we also observed increased EC from the right NACC to the left pre-SMA. Moreover, the effective strength from the right NACC to the left pre-SMA mediated the association between addiction severity (MAST scores) and impulsive scores. These results suggested that AUD individuals exhibit excessive sensitivity to rewarding reinforcement (e.g., alcohol consumption), and are significantly impaired in their ability to inhibit the impulsiveness to seek such rewarding reinforcement. These may be the underlying neural bases for impulsive alcohol consumption.
