Neuropsychopharmacology. 2016 Aug 11. doi: 10.1038/npp.2016.147.
Addiction involves an inability to control drug seeking behavior. While this may be thought of as secondary to an overwhelming desire for drug, it could equally well reflect a failure of the brain mechanisms that allow addicts to learn about and mentally simulate non-drug consequences. Importantly, this process of mental simulation draws upon, but is not normally bound by, our past experiences. Rather we have the ability to think outside the box of our past, integrating knowledge gained from a variety of similar and not-so-similar life experiences to derive estimates or imagine what might happen next. These estimates influence our current behavior directly and also affect future behavior by serving as the background against which outcomes are evaluated to support learning. Here we will review evidence, from our own work using a Pavlovian over-expectation task as well as from other sources, that the orbitofrontal cortex is a critical node in the neural circuit that generates of these estimates. Further we will offer the specific hypothesis that degradation of this function secondary to drug-induced changes is a critical and likely addressable part of addiction.