Confocal microscopy reveals putative TC contacts. A, Expression of synaptophysin-EGFP in VPM after AAV injection. B, C, Two excitatory neurons in L4 of somatosensory cortex juxtasomally filled with biocytin visualized under epifluorescence microscopy. Red, Biocytin-filled cells labeled with Alexa Fluor 594-conjugated streptavidin; green, synaptophysin-EGFP. C, Higher-magnification view of the region outlined in B. D, z projection of dendritic segment after confocal imaging and deconvolution demonstrates adequate x and y resolution to distinguish spine heads and spine necks. E, y projection of the same image stack illustrating z resolution. F, y projection of same image stack before deconvolution. G–J, Examples of a subset of spines apposed to markers for presynaptic vesicle pools in TC boutons. Green in G–I, synaptophysin-EGFP; in J, anti-VGluT2.