Neural correlates of choosing alcohol over a palatable food reward in humans.

Abstract

Background: In a population of light and heavy, nontreatment seeking drinkers, we recently showed that choice for alcohol versus a concurrently available snack reward was sensitive to the relative cost of alcohol. Here, we examined the neural substrates of alcohol choice using functional magnetic resonance imaging (MRI) in a new sample of light and heavy drinkers.

Methods: Participants were scanned during the Concurrent Alcohol Food Choice task, and collected points associated with the images of alcohol or snack rewards that they could redeem at the end of the experiment. As cost manipulation, point values were equal or varied so that they favored alcohol or the snack reward. Linear mixed-effects models were used for the analyses of behavioral and brain data.

Results: In a replication of prior findings, alcohol choice was sensitive to the relative value of alcohol in both groups. Neural activations in, among others, orbitofrontal cortex and insula were associated to relative value during choice. In addition, we observed that choosing alcohol as opposed to snack engaged two separate sets of brain regions. We did not replicate our prior finding of increased choice preference for alcohol in heavy compared to light drinkers and found no between-group differences in brain activity.

Conclusions: Overall, we replicated intact sensitivity to relative costs of alcohol in heavy drinkers and found its associated brain activity regions involved in value and salience attribution. Alcohol choice engaged regions involved in value-based behavior while snack preference elicited activity in areas linked to externally oriented attention. The failure to replicate the between-group differences may be due to the artificial MRI environment or observed differences in personality traits.