Figure 3.

Differences in mAChR control in dorsal versus ventral striatum. a, c, Profiles of mean [DA]_o ± SEM versus time after stimuli (arrows) of either a single pulse (1p) or a high-frequency burst (4p; 100 Hz) in control (left) and in increasing concentrations of oxotremorine-M (Oxo-M) in CPu (a) and NAc (c). Data are normalized to peak [DA]_o released by 1p in controls. Post hoc Bonferroni's t tests for burst versus single pulse are all p < 0.001, n = 9. b, d, Mean peak [DA]_o ± SEM evoked by 1p (black fill) and 4p/100 Hz (gray fill) plotted versus Oxo-M concentration for CPu (b) and NAc (d). One-way ANOVAs for effect of Oxo-M, p < 0.001. Curve fits are sigmoidal concentration–response curves, R² > 0.87. 1p release: Hill slopes, −3.30 (b), −3.10 (d); IC₅₀, 320 nm(b), 180 nm (d). 4p release: Hill slopes, 2.50 (b), 1.48 (d); EC₅₀, 840 nm (b), 120 nm (d). e, Effect of Oxo-M on relative release by burst versus single pulses (4p:1p release ratio) in CPu (circles) and NAc (triangles). Data are normalized to maximum response for comparison between regions. Curve fits (solid lines) are sigmoidal concentration–response curves, R² > 0.88. EC₅₀ values (dotted lines) are significantly different from one another (p < 0.001; CPu, 510 nm; 95% confidence interval range, 450–580 nm; NAc, 210 nm; 95% confidence interval range, 180–250 nm). Asterisks (*) indicate significant difference in 4p:1p ratio response in CPu versus NAc, in post hoc Bonferroni's t tests, ***p < 0.001; n = 9.