Olfactory discrimination learning has no impact on survival and differentiation of 2-, 5-, and 9-week-old olfactory granular neurons. A, Behavioral performances in the olfactory discrimination learning task. B, Number of BrdU-IR cells. C, Illustration of BrdU-IR cells in the GCL of counterstained bulbar sagittal sections. D, Percentage of BrdU-IR cells expressing the neuronal marker NeuN in the GCL. n = 6–9 per group. Scale bar, 10 μm.