Fig. 5
NAc D1R neurons sparsely target NAc-projecting VTA DA neurons. a Schematic of the experimental protocol. Cre-dependent ChR2 was injected into the NAc of D1R-Cre mice, while retrograde tracer CTB-488 was injected into the DMS. Infected terminals (red) were optogenetically activated, and recordings were obtained from retrogradely labeled SNc projection neurons (green). DMS dorsomedial striatum. b Representative images of ChR2-mCherry and CTB-488 at the injection sites and their anterogradely and retrogradely labelings in the midbrain slice. Left, scale bars: 500 μm. Right, scale bar: 200 μm. c Whole-cell recordings from a DMS projecting SNc neuron did not respond to blue light (5 ms pulses at 20 Hz). d No DMS projecting SNc neurons showed connections with NAc D1R neurons (n = 12 cells from 3 mice). e Representative confocal images showing a retrogradely labeled SNc neuron that was TH-positive (magenta). Scale bar: 20 μm. f Schematic of the experiment. Cre-dependent ChR2 and retrograde tracer CTB-488 were injected into the NAc of D1R-Cre mice, and recordings were obtained from retrogradely labeled VTA projection neurons (green). g Images showing ChR2-mCherry and CTB-488 injection in the NAc and anterogradely and retrogradely labeling in the midbrain. Left, scale bars: 200 μm. Right, scale bar: 200 μm. h Representative traces of optogenetically generated picrotoxin (PTX, 100 μM)-sensitive postsynaptic currents recorded from a retrogradely labeled VTA neuron. i Ten percent of NAc-projecting VTA neurons showed connections with NAc D1R neurons (n = 19 cells from 3 mice). j Representative confocal images of VTA slices showing a retrogradely labeled neuron (arrowhead) was TH positive and another patched cell not retrogradely labeled (arrow) was TH negative. Scale bar: 20 μm
