Fig. 1.

H129 derived tracer H129-G4 (a) The schematic diagram of H129-G4 genome. Two binary GFP elements were inserted into the genome of H129 bacterial artificial chromosome (H129-BAC) at the indicated position. b Schema of the simplified M1 projection pathways. The M1 pathway has been simplified and only the representative M1 projection targets are displayed. M1, primary motor cortex; cont. M1, contralateral M1; S1, primary somatosensory cortex; PRh, perirhinal cortex; STh, subthalamic nucleus; CPu, caudate putamen. c–d Representative tracing result of H129-G4. H129-G4 was injected into M1 of wild-type C57BL/6 mice, and representative images of coronal brain sections were obtained at 4 days post infection (dpi). Representative regions are shown, and the boxed areas are presented in the right panels with a higher magnification. e A representative H129-G4 labeled single neuron. A representative GFP-labeled neuron in PRh is shown, and the magnified images of the dendritic segments with individual spines (e1 and e2) and the axon (e3) are presented in the right panels. f–k Combination of fMOST and H129-G4 tracing. The mouse brain obtained at 4 dpi was further processed to fMOST imaging. The 3D image of the whole brain was reconstructed (f). Representative brain regions, including the contralateral S1 (g), striatum (h) and the ipsilateral S1 (i), are shown in details. Representative single neuron images at the ipsilateral S1 (j) and the contralateral S1 (k) are also presented