Neat technique provides evidence for long-lived neurons
The NYT has a nice summary of a recent Cell paper, where investigators from the Karolinska Institute used a wonderfully innovative technique to determine the age of many cells, including neurons from visual cortex and the cerebellum.
The general idea is this: Up until 1963, above ground nuclear weapons testing was allowed, dispersing radioactive carbon (14C) into the atmosphere. This “tagged” carbon was integrated into all plants and animals at that time and, since 1963, at an exponentially decreasing amount. Thus, calibrated with pine tree trunk rings (which are produced every year), the scientists are able to judge the age of cells by seeing how much of the genomic DNA of the cell contains 14C. Genomic DNA is created during cell division and, as the authors show, it appears not to be regenerated since preserved cell specimens from different years show the characteristic exponential decay of 14C post-1963.
The neat finding is that several neurons, from cortex and cerebellum, are very old… in 50-60 year old cadavers, neurons were found that were just as old or nearly just as old as the cadavers. So, even if there is neurogenesis occuring, it is now almost certain that some of our neurons are with us throughout life.