Until a few years ago it was thought that, during adult life, the brain does not produce new neurons. However, this theory is not true, and now a team of scientists from the Karolinska Medical Institute (Sweden) has designed a technique based on the measurement ofCarbon-14to determine how many cells are generated per day in the human brain.
To carry out his study, which is published in the journalCell, researchers have developed a curious method. During the 1950s, during the Cold War, nuclear tests produced an increase in carbon 14 in the atmosphere. Through photosynthesis,this carbon was incorporated into the plants and from there it spread throughout the food chain. Years later, nuclear testing ceased and carbon-14 levels were lower again. When cells duplicate their chromosomes, this carbon 14 is integrated into the genome, and therefore constitutes a unique marker that indicates the age of these cells.
The researchers analyzed carbon 14 cells in the adult hippocampus by mass spectrometry, and came to the conclusion that about 1,400 new neurons are produced in our brain every day, and this rate decreases as we age. “For a long time it was thought that we are born with a certain number of brain cells, and that it is impossible to generate new neurons after being born,” explained Jonas Frisén, one of the authors. “Later it began to be thought that there is a certain renewal rate, but it was not known in what quantity, nor its importance for brain function. In this study we have provided evidence thatneurogenesis exists in the hippocampus throughout life, which suggests that the new neurons may contribute to the function of the human brain ”.
