Professor Fred Gage describes how he and his colleagues developed techniques to measure neurogenesis in human brain tissue.
To measure neurogenesis in animals, people had used a drug bromodeoxyuridine. Bromodeoxyuridine is an artificial nucleotide which incorporates into the DNA of cells that are undergoing division, it allows you to mark, permanently, when a cell divided and subsequently you can analyze how many cells divided in what time since the drug has been administered. While you can do this in animals, and look at different time points, looking in humans is a little more difficult. But it is interesting is this drug is used to assess the aggressiveness of tumors, to monitor tumor progression. So, together with a colleague in Sweden, we looked at patients that had been treated with bromodeoxyuridine to monitor their tumor progression and when they died, their brains were sent to us in California and we developed techniques to measure human brain tissue, to see whether or not there were BrdU labeled cells and whether or not they became neurons and so that was the procedure, the way we determined that it occurred in humans.