A paper in science journal Cell reports on a technique for carbon dating brain cells, based on the rise in atmospheric radiation from the testing of nuclear weapons during the Cold War.
This testing resulted in a large rise in world-wide levels of environmental radiation, peaking in the mid-1960s. Because this radiation was absorbed via CO2, the decay of radioactive carbon in the DNA of neurons can be used to date when these cells were ‘born’.
The study, led by neuroscientist Kirsty L. Spalding, examined the age of neurons in the occipital cortex – an area at the back of the brain important for the visual system.
The researchers found that the cells in this area were as old as the people studied, suggesting that new neurons are not created there.
Until a few years ago, it was thought that humans did not grow new brain cells after birth. It was discovered, however, that neurons regenerate in an area of the brain called the hippocampus, a structure known to be crucial for memory.
It is still unclear whether other areas of the brain regenerate, although this study suggests that, in the occipital lobe at least, neurons are not created anew.
Link to summary of study ‘Retrospective Birth Dating of Cells in Humans’.