fysdt writes: "Scientists have known for years that neurogenesis takes place throughout adulthood in the hippocampus of the mammalian brain. Now Columbia researchers have found that under stressful conditions, neural stem cells in the adult hippocampus can produce not only neurons, but also new stem cells. The brain stockpiles the neural stem cells, which later may produce neurons when conditions become favorable. This response to environmental conditions represents a novel form of brain plasticity. The findings were published online in Neuron on June 9, 2011."