This animation summarized cutting edge research that was published in Science Magazine for May 9, 2014. The title is "Hippocampal Neurogenesis Regulates Forgetting during Adulthood and Infancy" by Katherine Akers et al.
The experiment: First, shock the mice to instill fear. Then, give some of them running wheels. Then test them to see which remembered the shocks.
It turned out that the mice with running wheels forgot the shocks much more than the other mice. The idea is that running stimulates neurogenesis, or the stimulation of new neurons. This replacement of older neurons results in forgetting older memories.
This is important for studying infantile amnesia.
From the youtube page:
Why is it so hard to recall memories from early childhood? New research suggests that neurogenesis, or the generation of new neurons, could play a significant role in this "infantile amnesia," which occurs across a wide range of species, including humans.