to generate the behavioral output toward a reinforcing stimulus (O'Doherty, 2004), such that addictive drugs intensely activate the reward and motivation circuits, usurp systems underlying reward-related learning and memory, and hijack cognitive control resources (Baler and Volkow, 2006; Bechara, 2005; Everitt and Robbins, 2005; Garavan and Hester, 2007; Goldstein and Volkow, 2002). As a result, under addiction, the saliency value of a drug and its related cues are enhanced, while the inhibitory control is weakened, setting up the stage for an unrestrained cycle which leads to compulsive drug-seeking without regard to its negative consequences.
