Figure 3.

One week preexposure to an enriched environment soon after neuronal birth increases the number of new neurons responding to reexposure to the same environment. a, Confocal images of dentate granule cell layer triple immunostained with BrdU (green), c-fos (red), and NeuN (blue). Arrows indicate triple-positive cells. Scale bar, 50 μm. b, Density of BrdU⁺/NeuN⁺/c-fos⁺ cells in mice exposed to an enriched environment immediately before being perfused. c, Proportions of c-fos⁺ in BrdU⁺/NeuN⁺ cells. d, Proportions of c-fos⁺ in NeuN⁺ cells. **p < 0.005 by Fisher's LSD test.