Rationale: Approach and avoidance decisions are made when an animal experiences a state of motivational conflict inflicted by stimuli imbued with both positive and negative valences. The nucleus accumbens (NAc), a site where valenced information and action selection converge, has recently been found to be critically involved in the resolution of approach-avoidance conflict. However, the individual roles of the region's dopamine receptor D1 (D1R)- and D2 (D2R)-expressing medium spiny neurons (MSNs) in regulating conflict resolution have not been well established.
Objectives: Here, we examined the roles of NAc D1R and D2R in cue-elicited approach-avoidance decision-making.
Methods: Using a conditioned mixed-valence conflict paradigm, rats were initially trained in a radial maze to associate separate visuotactile cues with sucrose reward, foot shock punishment, and no outcome. Following acquisition of the cue-outcome associations, rats were subjected to a conditioned approach-avoidance conflict scenario, in which they were presented with a maze arm containing a superimposition of the reward and punishment cues, and another arm containing neutral cues.
Results: Post-training intra-NAc D1R antagonism (SCH23390) led to an avoidance of the arm containing the mixed-valence cue over the neutral arm, whereas intra-NAc D2R antagonism (sulpiride) resulted in rats exhibiting a preference for the mixed-valence arm.
Conclusion: Our results suggest that NAc D1R and D2R exert differential control over decision-making involving cue-elicited approach-avoidance conflict resolution.
Keywords: Anxiety; Approach; Avoidance; Dopamine; Punishment; Reward; Ventral striatum.