The brain can create memories before the age of two.

Surely some friend has explained that they remember things that happened to them when they were barely one year old. Others may go further and talk about previous experiences, even from the first few days after birth. Science has long said that all of this is false: the consensus is that the human mind doesn't form memories until two or three years old (in some exceptional cases, it could be a little earlier). Any image prior to that date has surely been constructed from what other people have told us, but it can't come from our own experiences. Or can it? A new study, recently published in the journal Science, questions this dogma and proposes that the brain is prepared to memorize earlier than we thought.

A superpower of the human brain

One of the "superpowers" of the human brain is its vast capacity to store information in the form of memories. It has been estimated that we can store about two and a half petabytes, about a thousand times the capacity of a normal computer's hard drive, or the equivalent of more than half a million HD movies. Accumulating all this data requires the participation of various areas of the brain, and one of the most important in creating new memories and coordinating everything is the hippocampus. However, during the first years of life, memory processes seem to malfunction. This peculiarity has a name: infantile amnesia. One of the most accepted hypotheses to explain it is precisely that the hippocampus takes a long time to mature, and until it is fully developed, memories are not even generated.

To better understand this phenomenon, the group led by Dr. Nicholas B. Turk-Browne of Yale University used the imaging technique known as functional magnetic resonance imaging, which measures the activity of specific brain areas, to study how memories are formed during the first years of life for 4 years of age. The participants were given an activity that required them to use their memory, for example, looking at an image of a face, object, or situation they had never seen before. First, they were shown the photograph for a couple of seconds, and a minute later, they were shown the same photo again. The hippocampus was the area they had first seen. Specifically, the posterior part of the hippocampus, an area associated with memories in the adult brain, was the one that worked the most. They had formed a memory.

We produce memories from the beginning, but we don't remember them.

This study would disprove the theory that proposes that the hippocampus doesn't function properly until after the age of two. However, the observed effect was greater in children over one year old, which suggests that there is indeed a period of slow maturation, although this doesn't mean that while it occurs, there isn't already some functioning memory. More complex memories would depend on another additional factor: language acquisition. Without having the tools to describe things, we also can't save them on the hard drive. "The limits of my language are the limits of my world," as the philosopher Ludwig Wittgenstein said.

According to these new results, then, the problem isn't that the brain needs to mature a few years before it's unable to form memories, but that it doesn't know how to access this initial data. Childhood memories would be stored somewhere, at least for a few years, but since they would have been created at a time when our minds weren't yet sufficiently structured, their position wouldn't have been correctly arranged, which is why we can't find them. It would be as if we were searching for information on the internet that wasn't indexed using the parameters understood by current search engines. No matter how many appropriate keywords we used, these old references would never appear in the results. In practice, it would be as if they didn't exist, because we wouldn't be able to access them.

The most immediate reaction would be to ask ourselves if we can find some way to locate these misclassified books in the immense library that is our brain, these memories that accumulate without our knowledge in some unknown and possibly little-used corner of the immense warehouse inside our heads. Right now, there are no proposals for a solution.

In mice, some progress has been made, using a technique called optogenetics, which allows specific neurons to be activated with light pulses, using probes implanted in the brain.