Fig. 6.

Mapping the direct projections from VTA-DA neurons with H129-ΔTK-tdT. a Schema of the direct projections from DA neurons at VTA. DA neuron, dopaminergic neuron; VTA, ventral tegmental area; CA3, Hippocampus CA3; Amy, amygdala; NAc, nucleus accumbens; PFC, prefrontal cortex. b–c Controls, the helper and H129-ΔTK-tdT alone. AAV-DIO-TK-GFP (b) and H129-ΔTK-tdT (c) was individually injected into the VTA of DAT-Cre mice, and the images were obtained at 21 (b) and 10 dpi (c), respectively. The injection sites are shown in the dotted boxes. d The starter neurons of H129-ΔTK-tdT transmission. AAV-DIO-TK-GFP and H129-ΔTK-tdT were injected into the VTA of DTA-Cre mice at Day 1 and 22 sequentially, and images were obtained at Day 25. The image of the injection site at VTA is shown (d1), and the representative regions are further presented with a higher magnification (d1-d3). The starter neurons, which express both tdTomato and GFP, are indicated with the white arrows. e–g Tracing the monosynaptic output of VTA-DA neurons. The animals were perfused at Day 32, and the coronal brain slices throughout the entire brains were observed. Representative images of VTA-DA neuron innervating regions, including hippocampus (e1–3), amygdala (e4–5), PFC (f) and NAc (g), are presented, and the boxed regions are further magnified