Accordingly, compulsive drug use would result from poorly developed (prefrontal) reflective

processes dependent on executive functioning, taken over by a fast motivational (amygdalar) impulse process (Bechara 2005; Wiers et al. 2007). This model integrates behavioral, emotional, and cognitive processes and thereby expanded the traditional concepts that relied on positive and negative reinforcement for compulsive drug use and relapse. In addition to the I-RISA model, the R788 datasheet Habitual Behavioral Model emphasizes the importance of a switch from goal-directed behavior Inhibitors,research,lifescience,medical to habitual behavior during the development of drug dependence. Habitual behavior would be less sensitive to outcome values and would lead to loss of voluntary control and the development of compulsive behavior, such as compulsive drug use.

The switch to habitual behavior would represent a progression from prefrontal cortical to striatal control Inhibitors,research,lifescience,medical and a switch from ventral to more dorsal striatal regions (Wood and Neal 2007; Everitt et al. 2008). Whether changes in neuropsychological functioning should be viewed as a vulnerability trait or a response to chronic drug abuse still needs to be elucidated. Several studies have provided evidence Inhibitors,research,lifescience,medical for the involvement of predisposing genetic and environmental factors (Morgan et

al. 2002a; Bevilacqua and Goldman 2009), while others Inhibitors,research,lifescience,medical have described similar neurobiological changes as a response to chronic drug use (Nader et al. 2002; Volkow et al. 2004), or have assumed that both processes are present and mutually enhancing (Nader et al. 2006). While early hypotheses were stated from a behaviorist and psychological point of view (Hull 1943), subsequent theories were increasingly based on neurobiological animal research. With time, studies focused on integrating results from animal and human studies, and neuroanatomical substrates and dysregulated Inhibitors,research,lifescience,medical neurotransmitter systems were hypothesized to underlie the motivation to administer drugs, while recognizing the important role of genetic along with social factors Resminostat as contributors in the pathophysiology of drug use and addiction. Importantly, recent models of addiction have increasingly incorporated neuropsychological aspects of drug dependence, aided by the rapid expansion of the field of functional neuroimaging (for a review on substrates and neurocircuitries considered important in drug dependence, see the recent reviews of Goldstein et al. 2009a; Koob and Volkow 2010). However, results of these imaging studies usually do not allow causal inferences to be made, which should also be kept in mind when reading this review.