Fig. 1

vChATs directly innervate dNGIs. a Monosynaptic anterograde tracing strategy shows the application of HSV-DIO-mCherry virus in ChAT-Cre^GFP+/+ mice for labeling postsynaptic cells (red) of vChATs (yellow). b A brain section (top) from a ChATs-Cre^GFP+/+ mouse shows GFP expression (green, top). 3 days after the injection of HSV-DIO-mCherry virus (0.2 μl), mCherry-expressing cells were detected in both the vDB (top) and dDG (red, middle and bottom) regions of ChAT-Cre^GFP+/+ mice. c GFP-expressing ChATs (green) in the section stained with anti-ChAT (red) in the vDB region (top). The mCherry-expressing cells (red) in the sub-granular zone of the dDG region stained with DAPI (blue, bottom). d The mCherry-expressing cells in the dDG region are co-labeled with anti-DCX (blue). e Monosynaptic retrograde tracing strategy shows that NGI^TVA/G+/+ mice were generated by crossing Nestin-Cre^ER mice with TVA/G^loxP/loxP mice. Following the administration of tamoxifen (TAM), ΔG-rabies-mCherry virus particles (red) were injected into the dDG region of the NGI^TVA/G+/+ mice for labeling presynaptic cells (red) of dNGIs (yellow). f A brain section reveals the TVA/G-GFP cells (green) in the dDG region and mCherry in both the dDG and vDB of a dNGI^TVA/G+/+ mouse 3 days after injection of the ΔG-rabies-mCherry virus particles (1.5 μl). g TVA/G^+/+ cells (green) in the dDG region were co-labeled with mCherry from the dNGI^TVA/G+/+ mice 3 days after injection of the ΔG-rabies-mCherry virus. h The mCherry⁺ cells (red) in the vDB region were co-labeled with anti-ChAT (blue) from the dNGI^TVA/G+/+ mice 3 days after injection of the ΔG-rabies-mCherry virus. a–h, similar results were seen in each of five experiments