Cue-reactivity in the ventral striatum characterizes heavy cannabis use, whereas reactivity in the dorsal striatum mediates dependent use

Abstract

Background Animal models of addiction suggest that the transition from incentive-driven to habitual and ultimately compulsive drug use is mediated by a shift from ventral to dorsal striatal cue-control over drug seeking. Previous studies in human cannabis users reported elevated trait impulsivity and cue-reactivity in striatal circuits, however, these studies were not able to separate addiction-related from exposure-related adaptations. Methods To differentiate the adaptive changes, the present functional magnetic resonance imaging study examined behavioral and neural cue-reactivity in dependent (n = 18) and non-dependent (n = 20) heavy cannabis users and a non-using reference group (n = 44). Results Irrespective of dependence status, cannabis users demonstrated elevated trait impulsivity as well as increased ventral striatal reactivity and striato-frontal coupling in response to drug cues. Dependent users selectively exhibited dorsal-striatal reactivity and decreased striato-limbic coupling during cue-exposure. An exploratory analysis revealed that higher ventral caudate cue-reactivity was associated with stronger cue-induced arousal and craving in dependent users, whereas this pattern was reversed in non-dependent users. Conclusions Together the present findings suggest that an incentive sensitization of the ventral striatal reward system may promote excessive drug use in humans, whereas adaptations in dorsal striatal systems engaged in habit formation may promote the transition to addictive use.