Your child forgets details of the awesome Thomas-themed party you threw when he turned 2 – even though he couldn’t stop talking about “tank engine ba-yoons” for weeks after. As parents, we may want our child to remember the fun forever, but memories do fade. Think about it. What do you recall about your life at that age?
A recent study reveals that the rapid growth of brain cells the first few years of life could be why.
“Infantile amnesia” is the absence of memories the first three years of our lives, explains Dr. Paul Frankland, senior scientist at the Hospital for Sick Children in Toronto and co-author of the study with his wife, Dr. Sheena Josselyn.
Both are researchers and parents, so they have experience observing their own child’s fading memories.
“When our daughter was 2, we went to the zoo, and she got scared by a goose,” Frankland says. “For several weeks after, she would tell the story of how this ‘duck’ went ‘quack-quack, I got scared, Daddy picked me up, and we went to see zebras.'” But when the parents ask their now-4-year-old about the event, she doesn’t remember it. Blame brain overload, dad says.
“That first period of our lives the brain is still developing. And the ongoing development is essentially incompatible with stably storing memories,” Frankland says. The scientists wondered if reducing the rate of development in the hippocampus – an area of the brain known for learning and memory – would increase infant memories. So they tested the theory in a lab.
Researchers in Canada taught young mice to go through a maze. Infant mice have trouble recalling information weeks later, like humans. But, when researchers slowed new nerve cell growth (neurogenesis) in the hippocampus, the mice retained the memory of the maze for a longer time period.
“The effects,” Frankland says, “are to increase infant memories by reducing neurogenesis. But at the same time you are actually going to make the hippocampus function much less efficiently going forward.” Memory loss in kids may seem contradictory, but forgetting is a sign of significant growth.
“Forgetting is often perceived as bad, like when we forget our keys or someone’s name,” Frankland says. “But we think forgetting everyday information is actually important for the efficient function of memory. You need to forget some details to retain the really important stuff.” The takeaway? Introduce your tyke to experiences, even if they don’t remember them.
“A rich and stimulating environment is always good for children. That’s going to have long-term benefits on their brain and their health,” Frankland says. “But don’t count on them remembering when they’re 15 about the great time they had at the aquarium when they were 2.”