Figure 1.

Ventral hippocampal input evokes disynaptic inhibition in the NAc. A, Schematic of AAV-mCherry injection into the vHPC to label projections to the NAc. B, Example of injection site in the vHPC (left) and fluorescent fibers in the NAc medial shell (middle), with an expanded view (right). C, Left, Confocal image showing distribution of fluorescent cells in the NAc of a D1-tdTomato × D2-EGFP mouse, with NeuN staining (blue) to identify neurons, and anti-GFP (green) and anti-RFP (red) antibodies to enhance fluorescent signals. Right, Quantification of D1+ and D2+ cells relative to total NeuN-labeled cells. D, Example two-photon images of D1+ and D1− MSNs filled with Alexa-594 via the patch pipette. E, Average vHPC-evoked EPSCs at −70 mV and IPSCs at +20 mV in D1+ (red) and D1− (black) MSNs, in the presence of the NMDAR antagonist CPP. The triangle indicates a light pulse. Addition of the AMPAR antagonist NBQX eliminates the IPSCs (dotted line), indicating a disynaptic response. F, Summary of EPSC amplitudes (left) and IPSC amplitudes (right) in D1+ and D1− MSNs, where connected data points indicate pairs of neurons. Data are presented as arithmetic means ± SEM. G, Ratio of D1+ to D1− current amplitudes for EPSCs and IPSCs. Data are presented as geometric means with 95% confidence intervals. Note the logarithmic axis. Scale bars: B, 300 μm; C, 100 μm; D, 20 μm. n.s., Not significant (p > 0.05). *p < 0.05; ***p < 0.001.