Localization of thalamic terminals and corticocollicular pyramidal neurons in layer 5 of the AC. A, Diagram of triple virus injection into the IC, MGB, and AC. The viruses injected into the IC and AC are complementary and require Cre-recombinase for GFP exp... Localization of thalamic terminals and corticocollicular pyramidal neurons in layer 5 of the AC. A, Diagram of triple virus injection into the IC, MGB, and AC. The viruses injected into the IC and AC are complementary and require Cre-recombinase for GFP expression, hence the split color label. B, Low-power micrograph showing the MGB injection site and anterogradely labeled fibers tracking to the AC. C, Low-power micrograph showing the GFP label, which includes labeled cells in the AC and associated descending projections to the IC. Dotted box corresponds to the areas analyzed in D–F. D–F, Images at high magnification showing putative thalamocortical contacts on dendritic spines (D, arrows), dendritic shafts (E, arrowhead), and cell bodies (F, asterisks). Bernard J. Slater et al. J. Neurosci. 2019;39:256-270 ©2019 by Society for Neuroscience