Researchers have studied the causes of memory loss from childhood

The first steps, the first words, a favorite toy or a birthday — most people can't remember almost anything from the first three or four years of their life. Scientists call this phenomenon childhood or infantile amnesia, and for more than a century they have been trying to understand why the brain erases such an important period of life. A new study in mice has shown that the answer may lie not in the absence of memory per se, but in the peculiarities of the formation of neural connections immediately after birth. The work not only helps to better understand the development of the brain, but also forces us to rethink how our earliest memories arise. About why the first years of life do not disappear without a trace and what new things scientists have managed to learn — in the material of Izvestia.

Why don't we remember the first years of life

The reason for the new discussion of childhood amnesia was a study published in the journal Nature Communications. Scientists have studied the development of the hippocampus, a brain region that plays a key role in forming memories, in laboratory mice. It turned out that immediately after birth, neural networks in this area are arranged quite differently than in adult animals: they contain a huge number of connections between cells, which eventually become more orderly and specialized.

The authors suggest that this "hyper-connectivity" helps the young brain learn as quickly as possible, but at the same time prevents the formation of accurate and stable episodic memories. In other words, the early brain is primarily focused on mastering a huge amount of new information, rather than on maintaining a detailed "chronicle" of events. As you get older, the unnecessary connections gradually disappear, and the remaining ones become more specialized, so that memory begins to work differently.

The study also supports an idea that is increasingly emerging in modern neuroscience: early memories may not disappear at all. Perhaps they continue to exist in the brain in the form of so-called latent memory traces, but an adult is no longer able to access them. Scientists have been discussing this hypothesis for several years, but new data allows us to look at it from the other side — through the features of the development of neural networks, and not only through the processes of forgetting.

At the same time, the researchers themselves emphasize that the results cannot be directly transferred to humans. The mouse brain and the human brain develop in different ways, and such experiments only allow us to test individual biological mechanisms. Nevertheless, it is animal studies that often become the first step towards understanding the processes, which are then confirmed in clinical observations and experiments involving humans.

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Memory appears sooner than it seems

For a long time, neuroscientists explained childhood amnesia by the fact that the infant's brain is not yet mature enough to form long-term episodic memories. However, modern research is gradually changing this point of view. More and more evidence suggests that the hippocampus begins to participate in memory formation at an early age, which means that the problem may lie not in the absence of memories themselves, but in the mechanisms of their subsequent retrieval.

This hypothesis is confirmed by more recent studies. The work, published in 2025, showed that the hippocampus of infants is able to encode new episodic memories already during the first year of life. This means that the mechanisms for recording information begin to work much earlier than the first conscious memories appear, which a person is able to tell in adulthood.

Therefore, today many experts consider childhood amnesia primarily as a problem of access to early memories. Recent research has shown that events from the first years of life can persist in the brain as latent memory traces and continue to influence human development, even if they are no longer able to consciously reproduce them. This hypothesis is gradually becoming one of the leading ones in the modern neurobiology of children's memory.

Why does the brain seem to "close the door" to early childhood

Despite decades of research, there is still no single explanation for childhood amnesia. Most neuroscientists believe that it does not arise from a single cause, but as a result of a combination of several processes occurring in the developing brain. The new study only adds another important element to this picture, but does not negate other hypotheses.

One of the most well-known modern theories is related to the intensive formation of new neurons in the hippocampus. In the first years of life, this process is much faster than in adults. According to the hypothesis of Canadian neuroscientists Paul Frankland and Sheena Josselin, such a high rate of neurogenesis can literally rebuild existing neural networks, which makes previously formed memories difficult to access or even cease to be retrieved. This does not mean that memory disappears completely, but rather that the architecture of the brain itself is changing so quickly that the "key" to old memories is lost.

There are also psychological explanations. Some researchers associate the emergence of stable autobiographical memories with the development of speech, self-esteem, and the ability to build events into a coherent story. As long as a child does not recognize himself as a separate person and does not know how to describe what is happening in words, it is more difficult for the brain to form memories in the form in which an adult can then restore them years later. At the same time, experts emphasize that these hypotheses do not contradict biological ones: most likely, childhood amnesia occurs due to a combination of brain maturation, cognitive development, and changes in memory.

Early childhood stays with us, even if we don't remember it.

The absence of conscious memories does not mean that the first years of life pass without a trace. On the contrary, it is during this period that the basic mechanisms of learning, emotional regulation, attachment and reaction to the outside world are formed. A child may not remember specific events, but the accumulated experience continues to influence brain development, behavior, and the ability to interact with other people.

That is why research on children's memory is important not only for understanding why we forget our own infancy. They help us understand how the human brain develops, why early life experiences are so important, and what mechanisms underlie some neurological and psychiatric disorders. The better scientists understand the processes of memory formation, the more opportunities there are to study developmental disorders and find new approaches to their therapy.

The new work on mice does not provide a definitive answer to the question of where our earliest memories disappear to. However, it reinforces one of the most intriguing modern ideas: perhaps the events of the first years of life are not completely erased. They can persist in the brain for much longer than previously thought, but as they get older they become almost inaccessible for conscious reproduction. And if this hypothesis is confirmed in future research, scientists will have to re—answer the question that has been bothering people for more than a century: do we really forget our childhood - or do we simply no longer know how to return to it.