Extended Data Figure 4. Evaluation of retrograde infection by CAV-Cre.

a, Representative images of the injection sites where CAV-Cre plus retrobreads were delivered into the olfactory bulb, dorsal hippocampus, auditory cortex, cerebellum, or medulla of the Ai14 Cre reporter mice (see Methods for coordinates). Red, tdTomato; green, retrobeads; blue, DAPI. tdTomato labeling was densest at the injection site, and corresponded with the presence of retrobeads. We did not observe dense tdTomato or retrobeads labeling in other brain regions adjacent to the injection site unless these sites sent direct projections to the injection site, indicating that for our experiments, CAV-Cre was efficiently and specifically delivered to the targeted brain regions. n=4 per injection site. b, Representative coronal sections of brain regions that contained tdTomato+ labeling of specific cell populations known to project to CAV-Cre injection sites. Below is a partial list: neurons projecting to OB (1^st column): ipsi- and contralateral anterior olfactory nucleus (AON), piriform cortex (Pir), nucleus of the lateral olfactory tract (nLOT), but not contralateral OB; to dorsal hippocampus (2^nd column): lateral and medial septum (LS, MS) and entorhinal cortex (Ent); to auditory cortex (3^rd column): somatosensory cortex (SC), entorhinal cortex (Ent), and medial geniculate nucleus (MGN); to cerebellum (4^th column): contralateral pontine nuclei (PN) and inferior olive (IF); to medulla (5^th column): insular cortex (Ins), central amygdala (CeA), and paraventricular hypothalamic nucleus (PVH). Coronal images are composites generated from two overlapping tiled images. Insets show high magnification images of boxed regions. Bottom, sagittal schematic of the CAV-Cre injection sites (a) and the approximate location of the two representative coronal sections above. Scale, 1 mm; inset, 100 μm.