Functional imaging of an alcohol-Implicit Association Test (IAT)

This research assessed activation in neural substrates involved in implicit associative processes through functional magnetic resonance imaging of an alcohol-Implicit Association Test (IAT) focused on positive outcomes of alcohol use. Comparisons involved 17 heavy and 19 light drinkers, ranging in age from 18 to 22, during compatible and incompatible association task trials. Behaviorally, a significant IAT effect was found with heavy drinkers showing stronger positive implicit associations toward alcohol use than light drinkers. Imaging data revealed heavy drinkers showed greater activity during compatible trials relative to incompatible trials in the left putamen and insula while no significant difference in activity between conditions was found in the light drinkers. Light drinkers showed significantly more activity in the left orbital frontal cortex during both compatible and incompatible trials than heavy drinkers, and the dorsolateral prefrontal cortex was engaged more in both light and heavy drinkers during incompatible trials relative to compatible trials. Further, within-group analyses showed significant amygdala activity along with the putamen and insula among heavy drinkers during compatible trials relative to incompatible trials. These results are consistent with a dual process framework of appetitive behaviors proposing that (1) implicit associations underlying habit are mediated through neural circuitry dependent on the striatum, and (2) controlled behaviors are mediated through neural circuitry more dependent on the prefrontal cortex. This is the first study to evaluate the neural mechanisms elicited by an alcohol-IAT, providing an additional step toward increasing understanding of associative habit processes and their regulatory influence over addictive behaviors.