Alcohol attenuates amygdala-frontal connectivity during processing social signals in heavy social drinkers A preliminary pharmaco-fMRI study

Convergent evidence shows that alcohol exerts its effects on social behavior via modulation of amygdala reactivity to affective stimuli. Given that affective processing involves dynamic interactions between the amygdala and the prefrontal cortex (PFC), alcohol's effects are likely to extend beyond regional changes in brain activity to changes that manifest on a broader functional circuit level. The current study examines alcohol's effects on functional connectivity (i.e., coupling) between the amygdala and the PFC during the processing of socio-emotional stimuli using functional magnetic resonance imaging (fMRI). In a randomized, double blind, placebo-controlled, within-subjects cross-over design, 12 heavy, social drinkers performed an fMRI task designed to probe amygdala response to socio-emotional stimuli (angry, fearful, and happy faces) following acute ingestion of alcohol or placebo. Functional connectivity between the amygdala and PFC was examined and compared between alcohol and placebo sessions using a conventional generalized psychophysiological interaction (gPPI) analysis. Relative to placebo, alcohol reduced functional coupling between the amygdala and the right orbitofrontal cortex (OFC) during processing of both angry and fearful faces. Alcohol also reduced functional coupling between the amygdala and left OFC during processing of happy faces. These preliminary findings suggest that alcohol's effects on social behavior may be mediated by alternations in functional connectivity between the amygdala and OFC during processing of emotional faces.