Nucleus accumbens plays a central role in reward processing (Baler and Volkow, 2006; Knutson and Wimmer, 2007). It is widely accepted that the initial reinforcing effects of most drugs of abuse rely heavily upon the induction of large and rapid increases in the level of dopamine in the NAc, which can render the drugs as highly salient, drive motivation and produce compulsive behaviors (Nestler, 2005; Volkow et al., 2007). Ventral/rostral ACC is the affective subdivision of ACC and primarily involved in assessing the salience of emotional and motivational information and regulating emotional responses (Allman et al., 2001; Bush et al., 2000). This subdivision has extensive connections with other limbic areas including the striatum and amygdala (Kalivas and McFarland, 2003). In drug addicts, increased activity in ventral/rostral ACC was found to be associated with their subjective experience of drug craving (Diekhof et al., 2008; Volkow et al., 2005). The OFC is a major area of motivation, drive and salience evaluation, which is impaired in drug addicts and plays an important role in the output of compulsive drug-seeking behaviors (Volkow and Fowler,
