“…Rats were first trained to self‐administer saline or oxycodone (6 h/day × 10 days, 0.15 mg/kg/infusion) (Figure 1A). These experimental conditions were chosen based on previous studies showing incubation of craving with a 0.1‐ to 0.15‐mg/kg/infusion dose and 3‐ to 6‐h daily sessions 12,14,30,31 and because this dose has been shown to lead to an escalation of drug intake, a translationally relevant marker of addiction 32 . A two‐way ANOVA found significant main effects for oxycodone self‐administration day [ F (9,234) = 3.014, p = 0.002] and nose‐poke hole [ F (1,26) = 357.7, p < 0.0001], and a significant day × nose‐poke hole interaction [ F (9,234) = 9.042, p < 0.0001], indicating that oxycodone self‐administering animals learned to discriminate between active and inactive holes and formed a strong preference for the oxycodone‐associated hole (Figure 1B), unlike saline self‐administering controls, where we saw no main effect of nose‐poke hole [Figure 1C; F (1,15) = 4.445, p = 0.9983].…”