Fifteen years ago a study found evidence for such neurogenesis in adults up to the age of 72 (Nature Medicine, doi.org/b7hjfz), but the research relied on a chemical called bromodeoxyuridine (Brd U) to label neurons.
Brd U was used at the time to track the spread of tumours in people with cancer, but it was banned shortly after and so the study was never repeated, leading some researchers to question the results.
Spalding and her postdoc advisor Jonas Frisén had a hunch that a pulse of radioactive carbon created by above-ground nuclear tests during the Cold War could help solve the riddle.
“A geopolitical phenomenon—this Cold War bomb testing—has, in a way, put a date stamp on everything and everybody,” Spalding says.
If one was done in the middle of the ocean...unless it was reported..would never even know. These element podcasts connect A LOT of info to their 8th grade brains.
I have been a faithful fan of Radiolab for past 5 years.
Instead of chemical labelling, Jonas Frisén at the Karolinska Institute in Stockholm, Sweden, and colleagues used a by-product of the above-ground nuclear bomb tests carried out by the US, UK and Soviet Union between 19.The ratios are consistent among species, and the slight (1-3%) differences can also be calculated from the ratio of C) decreases as the radiocarbon decays. Libby determined, one gram of pure carbon should produce about 14 (13.56) radioactive decays per minute. The Beta-counting method detects the rate at which purified carbon decays. A rate of 7 decays/gram/minute would indicate an age of one half-life, or 5730 years old. That’s because some cells are born after you are, sometimes many many years after, but we’re not really sure which ones, or when — it’s not as if there are cellular birthday parties, marked by balloons and cake.So the question of age remained relatively unanswered until the early aughts, when scientist While Mary Webster has a very interesting analysis of tissue age, she is apparently unaware of the natural production of C-14 by cosmic rays in the upper atmosphere.