Figure 1. Retrogradely labeled neurons in LEC following viral injections into the olfactory bulb (GFP) or the aPCX (mCherry). Labeled neurons were distributed throughout the LEC, especially in layers II–V in the ipsilateral LEC, with the most robust labeling observed after aPCX infections. With these markers, no double-labeled cells were observed in any animal. A, Left, Section labeled with RV-GFP (olfactory bulb) and RV-mCherry (aPCX); right, annotated corresponding to the section (bregma 5.3) adapted from (Paxinos and Watson, 2009). Scale bar, 2 mm. B–E, Higher-magnification images of boxed regions in (A). B,D, High-magnification of lamina II–III. C, E, High-magnification of lamina V–VI, from adjacent sections for illustration. Scale bar, 100 μm. F, G, High-magnification images of the labeled neurons in lamina V–VI in contra lateral LEC. Scale bar, 100 μm. H, Schematic representation of the rabies viruses mediated retrograde tracing of the projection neurons from LEC to the olfactory bulb and aPCX. I, Quantification of mean cell counts across animals (n = 7) in the different lamina ipsilateral and contralateral to the OB and aPCX infections. Here and in all subsequent figures, data are presented as mean ± SEM.