Figure 4.

DR neurons project to and activate the MeA. A–E, Schematic drawing of ChR2-EYPF injections into the DR and representative images of ChR2 expression in DR neurons (B) and axons at the MeA (C–E) three weeks later. F–K, c-Fos labeling of mice photostimulated at the DR-MeA. L–U, Quantification of total number of cells (L–M) and percentage (Q–U) of c-Fos⁺ cells in the MeA (MeAa, anterior MeA; MeApd, posteriordorsal MeA; MeApv, posteriorventral MeA) for D–K. Only cells within the MeA were counted. One slice was quantified per area per animal. Animal number is indicated in bars of bar graphs. Scale bars: 200 μm (A); 200 μm (low-magnification images of B–D, low-magnification images of F–K); 50 μm (high-magnification images of F–K). Data are presented as mean ± SEM; *p < 0.05, **p < 0.01. Statistics can be found in Table 2.