Fos-expressing neuronal ensembles play a causal role in the expression of food-seeking behavior. A, B, Experimental timeline (A) and self-administration data (B) in wild-type rats. C, Representative images (scale bar is 20 μm) and quantification of Fos⁺ PLC neurons (*p < 0.05; no test–day 1: n = 6, no test–day 10: n = 6, test–day 1: n = 10, test–day 10: n = 10). Scale bar, 20 μm. D–F, Experimental timeline (D) and food self-administration (E). F, Cannula placement for Daun02 inactivation experiment. H, I, Lever-pressing behavior in FosLacZ rats on test day (*p < 0.05; vehicle: n = 19, Daun02: n = 18). Shown are representative images of B-gal staining (H) and B-gal quantification (I) after Daun02 inactivation (*p < 0.05; vehicle: n = 16, Daun02: n = 16). Scale bar, 20 μm.