Persistent increases in the pool of doublecortin-expressing neurons in the hippocampus following spatial navigation training.

In addition to its role in neuronal migration during embryonic development, doublecortin (DCX) plays a role in hippocampal neurogenesis across the lifespan. Hippocampal neurons exhibit a high degree of synaptic plasticity while they are in the DCX phase. While previous studies have reported that behavioral training on hippocampus-dependent tasks can enhance neuron survival, little was known about the stage of development of those neurons and, particularly, whether a large pool of the surviving new neurons remains in the DCX phase for a prolonged period after training. Here we report that spatial navigation training increases the pool of neurons that are in the DCX phase 4 weeks after training ended. Thus, the stock of DCX-expressing neurons in the hippocampus is affected by whether a hippocampus-dependent task has been encountered during the preceding few weeks.