Positive experience increases c-Fos expression in basolateral amygdala, nucleus accumbens and ventral tegmental area. Whole brain c-Fos staining shows that positive experience (A′-E′), but not neutral experience (A–E), elicits increase of c-Fos expression in basolateral amygdala (BLA) (A, A′), nucleus accumbens (NAc) (B, B′), ventral tegmental area (VTA) (D, D′), but not in the medial prefrontal cortex (mPFC, including prelimbic (PrL) and infralimbic (IL)) (C, C′), substantia nigra (SN) (D, D′), interpeduncular nucleus (IPN) (D, D′) or dentate gyrus (DG) (E, E′). Statistical analysis of the histological data revealed a significant increase of c-Fos expression in basolateral amygdala (F, two-tailed unpaired t-test, t(12) = 2.993, P = 0.0112), nucleus accumbens (G, two-tailed unpaired t-test with Welch's correction, t(7.109) = 2.747, P = 0.0282) and ventral tegmental area (I, two-tailed unpaired t-test with Welch's correction, t(6.687) = 3.788, P = 0.0074). Neutral experience group n = 7; positive experience group n = 7. *P < 0.05, **P < 0.01. Data are presented as means±SEM. Annotation (AP): distance from the bregma (mm). Scale bars correspond to 100 μm.