Impulsivity was studied using a temporal discounting task known as intolerance-to-delay (ITD) during which animals selected either an immediate single-pellet or a delayed 5-pellet reward. Novelty-seeking and heroin-induced locomotor activity were assessed in open-field arenas. For self-administration (SA) experiments, rats were trained to intravenously self-administer heroin, then underwent extinction training and cue-induced reinstatement. For details, see Supplementary Information.
