Figure 7.

Presynaptic connectivity mapping of excitatory neurons shows multiple types of interneuron inputs in the somatosensory cortex. RabV-GFP infection of Emx1 lineage cells in the cortex at P21 and analysis at P28. Connected cells are located throughout the cortex. A, Section of bregma at 1.98 mm. A′, Magnification of secondary motor cortex showing infection of connected cells. B, Section of bregma at 0.50 mm. B′, Magnification of second motor cortex showing infected connected cells. C, Section of bregma at −0.82 mm. C′, Magnification of dysgranular region and shoulder region of the primary somatosensory cortex showing infected connected cells. D, Section of bregma at −1.06 mm. D′, Magnification of the ventral thalamus showing infected connected cells. E, Section of bregma at −1.34 mm. E′, Magnification of ventral thalamus depicting infected connected cells. F, Section of bregma at −1.70 mm. F′, Magnification of primary somatosensory cortex showing infected connected cells. G, Section of bregma at −2.46 mm. G′, Magnification of primary and secondary visual cortex showing infected connected cell. H, Section of bregma −2.80 mm. H′, Magnification of primary visual cortex showing infected connected cell. I, Section of bregma at −328 mm. I′, Magnification of primary visual cortex and lateral secondary visual cortex showing infected connected cells. J–L, 3D representation of thresholded GFP pixels (green), red- and green-colabeled pixels within connected cells (yellow), and cell nuclei (blue), providing a visual reference. For clarity, views were chosen slightly off angle from coronal, sagittal, and horizontal views. M, Higher-magnification optical sections illustrate initially infected (yellow) and connected cells (green only), and DAPI (blue). Scale bars: A, 1 mm; A′, 100 μm.