The insula and drug addiction: an interoceptive view of pleasure, urges, and decision-making.

We have recently shown that damage to the insula leads to a profound disruption of addiction to cigarette smoking (Naqvi et al., Science 315:531-534, 2007). Yet, there is little understanding of why the insula should play such an important role in an addictive behavior. A broad literature (much of it reviewed in this issue) has addressed the role of the insula in processes related to conscious interoception, emotional experience, and decision-making. Here, we review evidence for the role of the insula in drug addiction, and propose a novel theoretical framework for addiction in which the insula represents the interoceptive effects of drug taking, making this information available to conscious awareness, memory and executive functions. A central theme of this framework is that a primary goal for the addicted individual is to obtain the effects of the drug use ritual upon the body, and representations of this goal in interoceptive terms by the insula contribute to how addicted individuals feel, remember, and decide about taking drugs. This makes drug addiction like naturally motivated behaviors, such as eating and sex, for which an embodied ritual is the primary goal.