Time bomb

From Science:Brain_3

Nuclear bomb testing in the 1960’s is providing a way for researchers to tell when cells in the brain were “born”. The bombs released large amounts of carbon-14, which was quickly taken up as CO2 by plants and animals. Measurements of this isotope indicate that neural cells in the cerebral cortex are as old as the individual, researchers report in the 15 July issue of Cell, providing further proof that neurons in adult brains do not regenerate. (Photo credit, (abomb) clipart.com; (brain) corbis).

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