Figure 4.

Developmental time course of dopamine (DA) receptor modulation of evoked firing frequency of pyramidal neurons in layer V of the prelimbic cortex (PrL-C). (a) D₁ and D₂ receptor modulation of firing frequency of layer V pyramidal neurons from preadolescence through adulthood. Percentage of cells that respond to D₁ (increased firing; circle) or D₂ (decreased firing; square) receptor modulation of evoked firing by the D₁ receptor agonist SKF38393 (5 μM) or the D₂ receptor agonist quinpirole (5 μM). The four developmental age groups tested were preadolescence (PD14–21), early adolescence (PD28–35), late adolescence (PD46–58), and adult (>PD90). (b) Percent increase from baseline firing frequency following D₁ stimulation only in those cells from panel a that responded to D₁ receptor stimulation. D₁ receptor stimulation resulted in a significant increase in firing frequency in all developmental age groups (n=2–8 cells per developmental age group; **p<0.01, ***p<0.001, and ****p<0.0001). (c) D₂ receptor modulation of firing frequency in layer V pyramidal neurons from preadolescence through adulthood. Shown is the percent reduction from baseline firing frequency following quinpirole only in those cells from panel a that responded to quinpirole. Bath application of quinpirole resulted in a significant reduction in evoked firing frequency at all time points (n=8 cells per group; *p<0.05, **p<0.01, and ****p<0.0001). All values represent the mean±SEM.