The more difficult a learning task, the more new neurons survive, neuroscientist Tracey Shors of Rutgers University reported at SfN.
Previous research revealed that in certain regions of the brain, including the hippocampus, hundreds to thousands of new nerve cells are “born” every day, a process known as neurogenesis. This finding reversed the long-held belief that the brain could not regenerate its cells, and it has started a wildfire of scientific inquiry to understand neurogenesis better.
One curiosity is that more than half of the new neurons typically die within a few weeks. This raises some critical questions, Shors said: “Why generate all those cells only to have them die? Are they used for something?”
The possibility that they might have a role in memory and learning is a popular hypothesis. After all, newborn cells have several characteristics that would appear to be useful to learning: they have no previous experience and therefore no existing synaptic connections, yet they have the ability to make new connections. Moreover, there is continuous turnover built into their population.
Animal studies have shown that good learners do indeed retain more new cells than poor learners, and poor learners have a rate of cell survival no higher than animals that did not learn at all. There is also some evidence that these new cells might be used in memory processing, Shors said.
“Learning rescues cells from death,” she said. “The more engaging the task, the more effectively the new cells are rescued. It doesn’t seem to be an ‘all-or-nothing’ phenomenon.”