The generation of neurons from precursor cells occurs in the hippocampus throughout the lifespan of humans, but the extent to which this occurs in other brain structures in adult primate species has ignited much controversy. Now, Aurélie Ernst and her colleagues report that the adult human striatum is capable of generating new interneurons (Cell 156, 1072–1083, 2014 ).

The researchers obtained postmortem tissue from individuals who had received a thymidine analog as part of cancer treatment; cells incorporating the analog are assumed to have divided during the course of the treatment. They found that some of the dividing cells in the striatum also expressed neuronal markers. They then carried out carbon-14 dating and cell nuclei sorting techniques in postmortem tissue. This determined that striatal interneurons tended to be the striatal neuron subtype that indicated they were generated sometime after the birth of the individuals, and that the rate of neuronal formation of this type tended to be much lower in patients with the neurodegenerative disorder Huntington's disease, which affects this brain region.

The extent to which these late-forming neurons contribute to striatal function or to regeneration after injury in humans remains an open question.