Premature responses under PPX are dependent on impulsivity and lesion severity. Linear regressions represent premature responses according to lesion compared to sham rats; Lower right panel represent the number of premature responses for sham rats according to the different dopaminergic drugs (2-way ANOVA). Data represent mean ± SEM; *p < 0.0001. LI: Low impulsive, Int: Intermediate, HI: High impulsive; PPX: Pramipexole, Apo: Apomorphine; TH+: Tyrosine Hydroxylase positive. Sham: LI: n = 5, Int: n = 12, HI: n = 4; Lesioned: LI: n = 6, Int: n = 11, HI: n = 6.