Sparse KO of GluN1 in L4 neurons does not affect thalamocortical terminal clustering. A, Experimental schema for in vivo calcium imaging and subsequent histologic analysis. B, Schematic of the Supernova-GCaMP6s/LacZ vectors for in utero electroporation. TRE, tetracycline response element; pA, polyadenylation signal; CAG, CAG promoter; ires, internal ribosome entry site; tTA, tetracycline transactivator; WPRE, woodchuck hepatitis virus posttranscriptional regulatory element. C, Representative confocal images of tangential sections from TCA-RFP; Grin1floxed/+ and TCA-RFP; Grin1floxed/floxed mice at P6. Supernova-GCaMP6s-labeled neurons in TCA-RFP; Grin1floxed/+ and TCA-RFP; Grin1floxed/floxed mice are control and GluN1KO neurons, respectively. D, The area, width (row), and length (arc) of C1 barrel (yellow line in the left panel) visualized as a thalamocortical axon cluster were quantified at P6. Number of animals: control, 7; GluN1KO, 4.