How widespread is adult neurogenesis in mammals?

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It is now widely accepted that neurogenesis occurs in two regions of the adult mammalian brain — the hippocampus and the olfactory bulb. There is evidence for adult neurogenesis in several additional areas, including the neocortex, striatum, amygdala and substantia nigra, but this has been difficult to replicate consistently other than in the damaged brain. The discrepancies may be due to variations in the sensitivity of the methods used to detect new neurons.

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Figure 1: Changes in the view of adult neurogenesis in the mammalian brain over the past 15 years shown on a schematic diagram of the adult rat brain.
Figure 2: Studies reporting no adult neurogenesis in the neocortex have presented unconvincing evidence for adequate BrdU and NeuN double labelling in the dentate gyrus.
Figure 3: Convincing evidence for adequate BrdU and NeuN double-labelled staining in the adult rat hippocampus.
Figure 4: The standards of evidence of adult neurogenesis are not applied evenly across brain areas.


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The author thanks C. Gross, B. Leuner, Y. Kozorovitskiy and E. Glasper for helpful comments on the manuscript.

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