Fig. 4. Output connectivity of Smad7^OE neurons.

a Schematic illustrating stereotaxic CTB injections into the corpus callosum to label contralaterally-projecting neurons in barrel cortex of adult control and Smad7^OE brains. b Retrogradely labeled (CTB⁺) neurons in the cortex contralateral to the injected corpus callosum. A high degree of retrograde label is found in supra- and infra-granular layers in both genotypes. In adults, L4 is sparsely labeled in controls compared to Smad7^OE (yellow asterisk). Anterograde labeling can also be observed as diffuse axonal signals (red arrowheads). c Retrogradely-labeled (CTB⁺) transfected L4 (GFP⁺) neurons in barrel cortex, contralateral to the injected area. Within L4, sparsely-distributed CTB⁺ neurons were labeled in controls. With Smad7^OE, an increased amount of CTB labeling was observed throughout L4. Example regions showing double-positive CTB⁺/GFP⁺ (yellow triangles) and CTB^-GFP⁺ (open triangles) transfected neurons are shown on the right. d–f Quantification of CTB⁺ neurons displayed as percentage of double-positive CTB⁺/GFP⁺ (of total number of electroporated GFP⁺ neurons) in L4 (d), L5 (e), and CTB⁺ density in L2/3 (f). Violin plots show distributions from 6 sections (on average) from 3 brains per genotype. Group means are displayed with error bars representing SEM. Asterisks indicate **p = 0.001, linear mixed-effects model with parametric bootstrap test (n = 19 sections from 3 control brains, n = 20 sections from 3 Smad7^OE brains). g Labeling of retrogradely projecting neurons in somatosensory cortex of Celsr3 control (flox/flox) and cKO brains at P18. Source data are provided as a Source data file.