A close friend once told me that one of her favorite aspects about being a parent is that she could experience what it was like to be a baby and toddler. "As adults, we have no recollection of what it was like to be that young," she said. "Watching my son grow up offers me a window into that part of my life."
The inability to remember memories in early childhood is known as "infantile amnesia". Few adults can remember events in their lifetime that occurred before the age of three. A past study shows that these memories tend to fade away around the age of seven.
But why can't we remember our days as a crawling, toddling, babbling youngster? Recent research suggests the answer many have to do with how quickly the brain develops during this stage in our lives. According to a Scientific American article published earlier this week:
In a new experiment, the scientists manipulated the rate at which hippocampal neurons grew in young and adult mice. The hippocampus is the region in the brain that records autobiographical events. The young mice with slowed neuron growth had better long-term memory. Conversely, the older mice with increased rates of neuron formation had memory loss.
Based on these results, published in May in the journal Science, [neuroscientists Paul Frankland, PhD, and Sheena Josselyn, PhD] think that rapid neuron growth during early childhood disrupts the brain circuitry that stores old memories, making them inaccessible. Young children also have an underdeveloped prefrontal cortex, another region of the brain that encodes memories, so infantile amnesia may be a combination of these two factors.