Figure 1.

D1R- and D2R-expressing SPN involvement in pERK-related activity associated with action–outcome encoding. A, B, Groups of D1- and D2-GFP mice (n = 4–6) were either trained to lever press for food pellets (trained) or received the food pellet delivery unpaired with lever pressing (yoked). Rate of magazine entries (two-way repeated-measures ANOVA, F_(1,48) = 6.8, p < 0.05; post hoc test, p > 0.05) and rate of lever presses (two-way repeated-measures ANOVA, F_(1,48) = 101, p < 0.01; post hoc test, **p < 0.01) were recorded and compared between the yoked and the trained mice. C, This training schedule induced a goal-directed outcome association, as a separate group of D1- and D2-GFP mice (n = 9 and 7, respectively) that were trained using the same schedule, demonstrated sensitivity toward outcome devaluation (one-way ANOVA, F_(1,30) = 10.4). *p < 0.01. D, The pERK-positive neurons in the pDMS (top) and DLS (bottom) were counted in the indicated regions of coronal sections (dashed line). E, The pERK-positive neurons in the pDMS (top) and DLS (bottom) were expressed as the percentage of D1R-expressing SPNs (GFP-positive cells in D1-GFP mice) and the D2R-expressing SPNs (GFP-positive cells in D2-GFP mice). The percentage of pERK-positive neurons among the D1R-expressing SPNs in the pDMS was significantly increased (F_(1,9) = 6.32). *p < 0.05, trained versus yoked in D1 group of the pDMS. Other comparisons in the top and bottom were not significant (all F values <1). F, Representative samples from D1-GFP mice illustrating the proportion of pERK-positive neurons in the pDMS in the yoked and trained groups.