Where do our early childhood memories go?

2024 Author: Seth Attwood | [email protected]. Last modified: 2023-12-16 15:55

Where do childhood memories go? Why does our brain know how to forget? Can you trust the shards of memory? The problem of childhood memories has been worrying scientists for several years, and recent research by psychologists and neurophysiologists can clarify a lot in these matters.

My memories are like gold in a wallet given by the devil:

you open it, and there are dry leaves.

Jean-Paul Sartre

Childhood. The river. Overflowing water. White sand. Dad teaches me to swim. Or here's another: luggage. You pick up all sorts of junk such as beads, colored glass, candy wrappers from sweets and gum, dig a small hole in the ground, throw your treasures there, press it all with previously found glass from a bottle and fill it with earth. Nobody ever found them later, but we loved to make these very luggage. My kindergarten memory has been reduced to these isolated moments: a drawing with my finger on the misted glass of a window, my brother's plaid shirt, a dark winter street strewn with red lights, electric cars in a children's park.

When we try to remember our life before the moment of birth, it turns out to see only such glimpses in the closet of memory, despite the fact that we thought about something then, felt something and learned a lot about the world in those days. Where have all these childhood memories gone, these years?

© Gerard DuBois

The problem of childhood memoriesand the inevitable forgetting fits into the simple definition of psychologists - "childhood amnesia." On average, people's memories reach the age when they were 3-3, 5 years old, and everything that happened before that becomes a dark abyss. Leading memory development expert at Emory University, Dr. Patricia Bauer, notes:

This phenomenon requires our attention, because there is a paradox in it: very many children remember the events of their lives perfectly, but, as adults, they retain a small part of their memories.

In the past few years, scientists have been particularly closely involved in this issue and, it seems, they have managed to unravel what happens in the brain when we lose memories of the very first years.

And it all started with Freud, who back in 1899 coined the term "childhood amnesia" for the described phenomenon. He argued that adults forgot about their early years in the process of suppressing interfering sexual memories. While some psychologists supported this claim, the most widely accepted explanation for childhood amnesia was that children under the age of seven were simply unable to form lasting memories, although the evidence to support this theory was scanty. For nearly a century, psychologists have assumed that childhood memories do not survive primarily because they are unable to last.

The end of the 1980s was marked by the beginning of the reformation in the field of child psychology. Bauer and other psychologists began to study children's memory using a very simple method: they built a very simple toy in front of the child and smashed it after the signal, and then they observed whether the child could imitate the actions of an adult in the correct order, but over an extended time range: from a few minutes up to several months.

Experiment after experiment has shown that the memories of children 3 years of age and younger actually persist, albeit with limitations. At 6 months of age, babies remember at least the last day; at 9 months, events are stored in memory for at least 4 weeks; at the age of two - during the year. And in a historical study (1) from 1991, scientists found that a four-and-a-half-year-old child could recall in detail a trip to Disney World that took place 18 months earlier. However, around the age of 6, children begin to forget many of these early memories. Another experiment (2) of 2005, conducted by Dr. Bauer and his colleagues, showed that children aged five and a half recalled more than 80% of the experience they had before the age of 3, while children, who were seven and a half years old, could remember less than 40% of what happened to them in childhood.

This work exposed the contradictions that lie at the very heart of childhood amnesia: young children are able to remember events in the first few years of life, but most of these memories eventually disappear at a rapid rate, unlike the forgetting mechanisms inherent in adults. …

Puzzled by this contradiction, researchers began to speculate: maybe, for lasting memories, we must master speech or self-awareness - in general, acquire something that is not too developed in childhood. But, despite the fact that oral communication and self-awareness undoubtedly strengthen human memory, their absence cannot fully explain the phenomenon of childhood amnesia. Eventually, some animals that have large enough brains in relation to their bodies, but lack language and our level of self-awareness, also lose memories that date back to their infancy (such as rats and mice).

The guesses lasted until scientists paid attention to the most important organ involved in the memory process - our brain. From that moment on, the problem of childhood memories became the subject of attention of neuroscientists around the world, and one after another, studies began to appear explaining the reason for the disappearance of our memory.

The point is that between birth and adolescence, brain structures continue to develop. With a massive wave of growth, the brain acquires a huge number of neural connections that shrink with age (at a certain stage, we just need this “neural boom” - to quickly adapt to our world and learn the most necessary things; this does not happen to us anymore).

Now, as Bauer found out, this specific adaptability of the brain comes at a price. While the brain is undergoing protracted development outside the womb, the brain's large and complex network of neurons that create and maintain our memories is itself under construction, so it is not able to form memories in the same way that the adult brain does. … As a consequence, long-term memories formed in the early years of our lives are the least stable of all that we have during our lives, and tend to decay during adulthood.

© Gerard DuBois

A year ago, Paul Frankland, a neurologist at Toronto Children's Hospital, and his colleagues published a study entitled “Hippocampal neurogenesis regulates forgetting in infancy and adulthood” (3), demonstrating another cause of childhood amnesia. According to scientists, memories not only get worse, but also become hidden.

Several years ago, Frankland and his wife, who is also a neurologist, began to notice that the mice they were studying had worsened on certain types of memory tests after living in a cage with a wheel. Scientists linked this to the fact that running on a wheel promotes neurogenesis - the process of the appearance and growth of whole new neurons in the hippocampus, an area of the brain that is important for memory. But while neurogenesis of the adult hippocampus is likely to contribute to learning and memorization, it may have to do with the forgetting process as the body grows. Just as only a certain number of trees can grow in a forest, the hippocampus can house a limited number of neurons.

As a result, something happens that happens in our life all the time: new brain cells displace other neurons from their territory or even sometimes completely replace them, which in turn leads to a restructuring of mental circuits that can store individual memories. The particularly high levels of neurogenesis in infancy, scientists suggest, are partially responsible for childhood amnesia.

In addition to experiments with a running wheel, the scientists used Prozac, which stimulates the growth of nerve cells. The mice that were given the drug began to forget the experiments that were carried out with them before, while the individuals who did not receive the drugs remembered everything and were well oriented in the conditions they were familiar with. Conversely, when researchers genetically engineered the neurogenesis of small animals to be harnessed, young animals began to develop much more stable memories.

True, Frankland and Joselin went even further: they decided to carefully study how neurogenesis changes the structure of the brain and what happens to old cells. Their last experiment is worthy of the wildest guesses of science fiction writers: with the help of a virus, scientists inserted a gene into DNA that is able to encode a protein for fluorescent light. As luminous dyes have shown, new cells do not replace old ones - rather, they join an already existing circuit.

This rearrangement of memory circuits means that while some of our childhood memories do fade away, others are stored in encrypted, refracted form. Apparently, this explains the difficulty with which we are sometimes given to remember something.

But even if we manage to unravel the tangles of several different memories, we can never fully trust the resurrected paintings - some of them may be partially or completely fabricated. This is corroborated by a study by Elizabeth Loftus of the University of California, Irvine, through which it became known that our earliest memories are insoluble mixtures of authentic memories, stories we have absorbed from others, and imaginary scenes invented by the subconscious.

© Gerard DuBois

As part of the experiment, Loftus and her colleagues presented the volunteers with several short stories about their childhood, told by relatives. Unbeknownst to the participants in the study, the scientists included a contrived story that was, in fact, a fiction - about the loss at the age of five in a shopping center. However, a quarter of the volunteers said they remembered it. And even when they were told that one of the stories was invented, some participants were unable to determine that it was a story about a shopping center.

Ferris Jabr, science journalist and deputy editor-in-chief of Scientific American, reflects on this:

When I was little I got lost in Disneyland. Here's what I remember: It was December and I watched the train through the Christmas village. When I turned around, my parents were gone. Cold sweat ran down my body. I started sobbing and wandering around the park looking for Mom and Dad. A stranger came up to me and led me to giant buildings filled with TV screens with video from the park's security cameras. Have I seen my parents on one of these screens? No. We returned to the train, where we found them. I ran to them with joy and relief.

Recently, for the first time in a long time, I asked my mother what she remembered about that day at Disneyland. She says it was spring or summer and that she last saw me near the remote control of the Jungle Cruise boats, not next to the railroad. Once they realized I was lost, they went straight to the center of the lost and found. The caretaker of the park really found me and brought me to this center, where my parents found me, who was enjoying myself with ice cream. Of course, no evidence of either her or my memories could be found, but we were left with something much more elusive: these little embers of the past, embedded in our consciousness, shimmering like fool's gold.

Yes, we lose our childhood memories in order to be able to grow and develop further. But, to be honest, I don't see any big trouble in that. The most precious, the most important thing we always take with us into adulthood: the smell of mother's perfume, the feeling of the warmth of her hands, the self-confident smile of her father, the brilliant river and the magical feeling of a new day - all those trunks of childhood that remain with us until the end.