Neurons are constantly being born in the adult hippocampus, a region of the brain central to memory formation, but whether they have a role in the making of new memories has been unclear.

Paul Frankland at the Hospital for Sick Children in Toronto, Canada, and his colleagues identified a way to target these new neurons in mice — by genetically manipulating the animals so that an injection of a natural toxin would kill the cells. The authors trained the mice on a memory task, then administered the chemical. The animals' memories faded, but did not disappear completely. For example, a mouse could still remember that a hidden platform was near a patterned visual cue — just not which pattern. The results suggest that adult-generated neurons are essential to the finer details of memory.

J. Neurosci. 31, 15113–15127 (2011)