Revisiting the role of the insula in addiction

Vita Droutman, Stephen J. Read, Antoine Bechara
2015 Trends in Cognitive Sciences  
Brain lesions that damage the insular cortex interrupt addictive behaviors, suggesting that drug addiction sensitizes the insula. However, neuroimaging studies seem to lead to an opposite picture: structural neuroimaging studies show reduced grey matter volume of the insular cortex (IC) of drug users, and functional neuroimaging studies show reduced IC activity when drug users perform decision-making tasks. These results have been interpreted as indicating that addictive behaviors are
more » ... with reduced interoceptive signaling within the IC. We use this apparent contradiction to examine possible roles of the insula in addiction, identify open questions, and explore ways to address them. Keywords insular cortex; drug dependence; smoking; decision-making The insular cortex (IC) has been known for a while as a receiver of interoceptive signals, and a necessary substrate for experiencing emotion and self-awareness [1-3]. More recently its role in attention and decision-making has been gathering increased attention [4] [5] [6] . A growing body of research indicates that the decision process is a dynamic interplay between an implicit or automatic appetitive system, which promotes cue-induced habitual behaviors, and the executive control/inhibitory prefrontal cortex system [7] . The insular cortex, activated by homeostatic imbalance (such as deprivation from drugs), or by reward cues, plays a key role in this balancing process [8] . Since addiction to substances is invariably associated with physiological states that give rise to strong interoceptive signals, and since it involves flaws in the decision process (e.g., choosing immediate rewards at the expense of long-term negative consequences), it is not surprising that the insular cortex was found to be strongly involved in addictive behaviors. However, the specific nature and mechanisms of insular involvement in addiction are unclear and what we do know seems somewhat paradoxical.
doi:10.1016/j.tics.2015.05.005 pmid:26066588 pmcid:PMC4486609 fatcat:qar2oydi5fad3nhxk3axjiojlu