The reinforcement learning theory of drug addiction has been influential for decades.1 Under this framework, drugs trigger dopamine (DA) release and exert their reinforcing effects through the mesolimbic pathway.1 This model can account for compulsive drug-seeking behaviors in addiction. However, many empirical findings remain unaddressed. In particular, accumulating evidence suggests that DA, delivered by either addictive drugs2 or by pharmacological treatments, such as the nicotine replacement therapy,3 is not sufficient to reduce craving. Craving persists even after compulsive drug-taking behavior stops,3 suggesting that craving and drug-seeking behavior are 2 distinct processes, despite the fact that they are often homogenized in laboratory settings......Please contact the library to request a copy of this article - http://bit.ly/1Xyazai