Infusion of glutamatergic receptor antagonists within the BNST blocks the excitatory drive from the infralimbic cortex on VTA dopaminergic neurons. A, Diagram of the stimulation, microinfusion, and recording protocol used in this experiment. Here, the IL was stimulated with a 100-pulse train, and the AP5 (100 μm) plus CNQX (50 μm) mixture was microinfused within the BNST in a total volume of 20–30 nl >15 s. B, PSTHs showing ILCx-evoked responses in a VTA DA neuron before and during CNQX plus AP5 infusion within the BNST. C–E, Graphs illustrating the effects of microinjection of CNQX plus AP5 within the BNST (black bars) on excitation (C) obtained after stimulation of the ILCx and on basal activity parameters (D, E). Microinjection of CNQX plus AP5 within the BNST prevented the short latency activation of VTA DA neurons evoked by ILCx stimulation but had no effect on the basal firing rate or bursting activity. Scores are percentages ±SEM of baseline response magnitudes (C) or basal activity parameters (D, E) for VTA DA neuronal responses evoked by ILCx electrical stimulation during microinjection into the BNST of aCSF (white bars), or a mixture of 50 μm CNQX plus 100 μm AP5 (black bars). Numbers of neurons recorded in each group are denoted in parentheses above each histogram bar. A two-tailed paired Student's t test was performed for excitatory responses, firing rate, and bursting activity. ***p < 0.001. REC, Recording electrode.