New neurons (white) integrating into hippocampus.JASON SNYDERAdult mice that exercised on a running wheel after experiencing an event were more likely than their inactive mates to forget the experience, according to a paper from researchers at the University of Toronto, published in Science today (May 8). The results suggest that the production of new neurons—neurogenesis—prompted by the exercise wiped out the mice’s memories. They might also explain why human infants, whose brains exhibit abundant neurogenesis, do not have long-term memories.
“In general, hippocampal neurogenesis has been thought to be the basis for memory and they’re suggesting that it’s the basis for amnesia,” said Thomas Insel, director of the National Institute of Mental Health. “That’s a very controversial and provocative concept.”
Infantile amnesia is common to all humans. Children typically do not develop long-term memories until age three or four. But why is that? Sheena Josselyn and her husband Paul Frankland, who are both neuroscientists at the University of Toronto, pondered precisely that question after noticing that their two-year-old daughter could easily remember things that happened within a day or two, but not several months in the past.
More specifically, they wondered whether it might have something to do with neurogenesis in the hippocampus—a brain region ...
