To take into account the different baseline activities of the GluA1+/+ and GluA1−/− mice, difference scores between each CS+ and corresponding CS− trials were calculated within mouse lines (Fig. 2C–D). In concordance with the data in Fig. 2A–B, morphine-induced activation was dose-dependent (conditioning dose effect, F2,170 = 61.02, p<0.001), and the animals sensitized to morphine (day effect, F3,510 = 131.73, p<0.001) in a dose-dependent manner (day×conditioning dose interaction, F6,510 = 30.10, p<0.001). However, the first morphine dose failed to activate the GluA1−/− mice (genotype effect and day×genotype interaction, F1,170 = 7.53, p<0.01 and F3,510 = 17.66, p<0.001, respectively).
