a, b, Drug effects on Ca2+ event rates of D1- (a) and D2-SPNs (b) across different speed bins following vehicle or drug + amphetamine treatment. c, d, Drug effects on the proximal co-activity of D1- (c) and D2-SPNs (d) across different speed bins following vehicle or drug + amphetamine treatment. Data are represented as mean ± s.e.m. (****P < 10−4, ***P < 10−3, **P < 10−2 and *P < 0.05 for comparison to vehicle + amphetamine treatment; Two-way ANOVA with Holm-Sidak’s multiple comparison test).