Using injections of thymidine-H3 to label the nuclei of dividing cells, Altman was able to use autoradiography to determine a neuronal birthdate for each cell in a rat's brain. This research revealed some degree of adult neurogenesis in the hippocampus and olfactory bulb of rats, and paved the way for the possibility of neuropoiesis in the adult mammalian brain.
The study by Altman, which used thymidine-H3 injections to track cell division and autoradiography to identify when neurons were born, revealed that some neurons are generated in the hippocampus and olfactory bulb of adult rats. This finding opened up new avenues for research into neurogenesis in the adult mammalian brain.