Figure 4. Effects of AMPA receptor and GABA_A receptor antagonists on synaptic currents evoked by intra-VTA stimulation recorded in VTA neurons.

A, representative signal averages obtained during baseline periods (Control), or during the indicated maximal drug effect in 2 different VTA neurons. The AMPA antagonist DNQX (10 μm) caused an approximate 50% reduction in synaptic currents evoked by intra-VTA stimulation, whereas the combined application of DNQX and the GABA_A receptor antagonist bicuculline (BIC, 10 μm) nearly eliminated these synaptic currents. B, mean time course of effects of DNQX alone and in combination with BIC on intra-VTA-evoked synaptic currents.