Figure 4. Enhanced VTA DA neuron population activity following ilPFC inactivation was prevented by inhibition of the RE. A, Representation of histological placements of infusion cannulae into the ilPFC and the RE (open circles). TTX or dPBS vehicle (VEH) was injected into the RE, followed immediately by injection of TTX or dPBS vehicle into the ilPFC. VTA DA neuron population activity, firing rate, and burst firing were then measured. B, Pharmacological inhibition of ilPFC increased population activity, while parallel inhibition of the RE prevented this effect. C, D, The firing rate of spontaneously active DA cells was not affected by any manipulation, while the percentage of cells firing in bursts was significantly enhanced in the TTX/TTX group. E, F, Distribution of firing rate and burst firing were not affected by infusion of NMDA into the RE (Kruskal–Wallis test, firing rate, H = 0.060, p = 0.99; bursting, H = 0.54, p = 0.91). *p < 0.05, ***p < 0.001 (one-way ANOVA, Tukey's post hoc). x-axis in B–D is infusions in RE/ilPFC. n = 7–11 rats/group; n = 40–83 neurons/group. Data are represented as mean ± SEM.