Figure 8.

Labeling of presynaptic input onto Sonic Hedgehog-expressing neurons in the motor cortex. Using Shh-Cre, ROSA-Tomato, ROSA-tTA, and pTRE-Bi-G-TVA mice injected with RabV-GFP virus at P21, layer V Shh⁺ cortical pyramidal neurons were targeted. Contralateral and subcortical inputs were complementary to injections in Emx1 somatosensory cortex, with many connections to ipsilateral somatosensory cortex and contralateral motor cortex. A, Section of bregma at 2.58 mm. A′, Magnification of motor cortex, yellow initially infected cells, green connected cells, and red Tomato⁺ cell. B, Section of bregma at 2.22 mm. B′, Magnification of secondary motor cortex, yellow initially infected cells, green connected cells, and red Tomato⁺ cell. C, Section of bregma at 1.10 mm. C′, Magnification of part of primary and secondary motor cortex, yellow initially infected cells, green connected cells, and red Tomato⁺ cell. D, Section of bregma at −0.22 mm. D′, Magnification of primary somatosensory cortex, yellow initially infected cells, green connected cells, and red Tomato⁺ cell. E, Section of bregma at −0.94 mm. E′, Magnification of primary somatosensory cortex, yellow initially infected cells, green connected cells, and red Tomato⁺ cell. F, Section of bregma at −1.58 mm. F, Magnification of primary somatosensory cortex, yellow initially infected cells, green connected cells, and red Tomato⁺ cell. G, Ipsilateral somatosensory cortex with RabV-GFP⁺ connected cells (green only). H, Contralateral motor cortex with RABV-GFP⁺ connected cells green only. G, H, DAPI staining of cell nuclei (blue). I–K, Reconstruction of pixels representing 3D distribution of connected cells (green) and initially infected cells (colabeled, yellow). Coronal, sagittal, and horizontal views of reconstructed brains shown slightly off angle for clarity. Scale bars: A, 1 mm; A′, 100 μm.