Q175 mice display compromised motivation and reward-evoked dopamine release in the NAc. A, Representative cumulative response record during a PR session in the two genotypes. Vertical ticks demarcate reward receipt. B, Mean (+SEM) breakpoints in WT (n = 8) and Q175 (n = 12) mice. C, Mean dopamine concentration ([DA]; +SEM) across all trials. D, Mean of the single, largest dopamine concentration increase (+SEM) in each animal. **p < 0.01, ***p < 0.001.