NUCLEAR bomb tests carried out during the cold war have had an unexpected benefit. A radioactive carbon isotope expelled by the blasts has been used to date the age of adult human brain cells, providing the first definitive evidence that we generate new brain cells throughout our lives.
In mammals, most types of brain cell are created at, or soon after, birth and are never renewed. But studies in rodents and monkeys have shown that even in adulthood new neurons continue to be created in the hippocampus, which is involved in learning and the formation of new memories. However, there has been some controversy over whether the same is true for humans.
Jonas Frisén at the Karolinska Institute in Stockholm, Sweden, and colleagues used the carbon-14 produced by above-ground nuclear bomb tests carried out between 1945 and 1963. The amount of carbon-14 in the atmosphere is mirrored in our cells at the time they are born. Using mass spectrometry equipment, the team measured the number of carbon-14 atoms trapped in cells in different brain regions and compared this to data for atmospheric levels of carbon-14. This allowed them to date the birth of a cell to within a year.
By looking at the hippocampus in 55 post-mortem brains aged between 19 and 92, Frisén's team found that a subset of neurons in an area of the hippocampus called the dentate gyrus are indeed created throughout adulthood (Cell, doi.org/ms8).
In effect, a small population of our brain cells remains permanently young, renewing itself continually. By modelling the process, the team estimated that 35 per cent of hippocampal cells regenerate and we create 1400 new neurons every day. "Everyone working on adult hippocampal neurogenesis is excited about this work," says Sandrine Thuret at King's College London.
This article appeared in print under the headline "Nuke tests reveal brain regeneration"
- New Scientist
- Not just a website!
- Subscribe to New Scientist and get:
- New Scientist magazine delivered every week
- Unlimited online access to articles from over 500 back issues
- Subscribe Now and Save
If you would like to reuse any content from New Scientist, either in print or online, please contact the syndication department first for permission. New Scientist does not own rights to photos, but there are a variety of licensing options available for use of articles and graphics we own the copyright to.