Dorsolateral neostriatum contribution to incentive salience: opioid or dopamine stimulation makes one reward cue more motivationally attractive than another.

Pavlovian cues for rewards can become attractive incentives: approached and 'wanted' as the rewards themselves. The motivational attractiveness of a previously learned cue is not fixed, but can be dynamically amplified during re-encounter by simultaneous activation of brain limbic circuitry. Here it was reported that opioid or dopamine microinjections in the dorsolateral quadrant of the neostriatum ( DLS) of rats selectively amplify attraction toward a previously learned Pavlovian cue in an individualized fashion, at the expense of a competing cue. In an autoshaping (sign-tracking vs. goal-tracking) paradigm, microinjection of the mu opioid receptor agonist ( DAMGO) or dopamine indirect agonist (amphetamine) in the DLS of sign-tracker individuals selectively enhanced their sign-tracking attraction toward the reward-predictive lever cue. By contrast, DAMGO or amphetamine in the DLS of goal-trackers selectively enhanced prepotent attraction toward the reward-proximal cue of sucrose dish. Amphetamine also enhanced goal-tracking in some sign-tracker individuals (if they ever defected to the dish even once). That DLS enhancement of cue attraction was due to stronger motivation, not stronger habits, was suggested by: (i) sign-trackers flexibly followed their cue to a new location when the lever was suddenly moved after DLS DAMGO microinjection; and (ii) DAMGO in the DLS also made sign-trackers work harder on a new instrumental nose-poke response required to earn presentations of their Pavlovian lever cue (instrumental conditioned reinforcement). Altogether, the current results suggest that DLS circuitry can enhance the incentive salience of a Pavlovian reward cue, selectively making that cue a stronger motivational magnet. [ABSTRACT FROM AUTHOR]