The reasons why people often forget their childhood memories have been revealed.

DNVN - Have you ever wondered why you can't remember your childhood memories? No matter how hard you try, you can't recall experiences from your early life? A recent study indicates that it's not that those memories don't exist, but simply that we can't access them once we've grown up.

Illustration photo: Sohu

This study, published in the journal Science on March 20th, followed 26 babies aged between 4.2 and 24.9 months. The babies were divided into two groups: one group under 12 months old and the other group between 12 and 24 months old.

In the experiment, babies were placed in an fMRI machine to monitor their reactions to a series of specific images, each appearing for about two seconds. Scientists focused on observing the activity of the hippocampus, the brain region responsible for memory, emotions, and the autonomic nervous system.

“The hippocampus is a structure deep within the brain that cannot be observed using conventional methods. Therefore, we developed a new approach to conduct memory experiments on children using MRI… Previously, studies of this type were primarily conducted while children were asleep because infants are constantly moving, difficult to follow instructions, and have short attention spans,” Dr. Nick Turk-Browne, professor of psychology at Yale University and lead author of the study, shared via email.

Dr. Simona Ghetti, a psychologist at the University of California, Davis, who specializes in research on memory development in children, said that previous studies have shown that infants are capable of encoding memories. However, what is special about this study is that it has established a link between the process of memory encoding and the activity of the hippocampus. Note that Dr. Ghetti was not involved in this study.

In the experiment, after a period of time, the children were shown two images side-by-side, including one familiar image and one new image. To determine the level of image recognition, scientists monitored the children's eye movements to assess which image held their attention longer.

If a child's gaze focuses more on a familiar image, it indicates they have good memory. Conversely, if the child doesn't show a clear preference between the two images, it may suggest their memory isn't fully developed.

“Eye movements are a tool that has been used in hundreds of studies on memory and classification in infants. Infants naturally direct their eyes toward things they find interesting, and researchers have taken advantage of this characteristic to understand the mechanisms of memory,” Ghetti said via email.

Illustration photo: K.sina

Analyzing the function of the hippocampus

After collecting the data, the research team analyzed fMRI scans from children who looked longer at familiar images and compared them to a group without a clear preference. Trials were excluded if children were not focused on the screen or had excessive movement, such as blinking, during the scan.

The results showed that memory encoding abilities differed across age groups. In older children, the hippocampus showed higher activity levels in encoding information. Additionally, only those over 12 months old showed activation in the orbitofrontal cortex, an area involved in memory and recognition decision-making.

“In adults, we tend to remember information that is important and directly related to our own experiences,” said Dr. Lila Davachi, a psychology professor at Columbia University. Although not involved in the study, she emphasized: “What is remarkable about this research is that it demonstrates that even from a very young age, the hippocampus of infants is involved in memory encoding, even when the images don’t have particular significance for the child.”

Currently, the exact reasons why children over 12 months old have better memory encoding abilities are not clearly understood. However, scientists hypothesize that this change may be related to major transformations in brain development.

“A child’s brain undergoes many significant changes during early childhood, including cognitive, language, motor, and biological development. In particular, the hippocampus develops rapidly during this period,” explains Dr. Turk-Browne.

Turk-Browne's research team is currently investigating why early childhood memories are not readily retrievable later in life. He hypothesizes that during infancy, the brain is not yet developed enough to provide precise "search keywords," making memory recall difficult in adulthood. The way memories are encoded may depend on the child's early experiences.

The significance of the neonatal period for parents

Dr. Ghetti encourages parents to consider the importance of the infancy period for their children, even though children may not be able to recall these experiences when they grow up.

At this age, children absorb a large amount of information, including the ability to learn language by associating sounds with meaning. In addition, they begin to form expectations about family members and explore the world around them, including the characteristics of objects.

Parents can observe this process by noticing that children react to songs or stories that are repeated many times. According to Dr. Davachi, this not only helps children memorize but also makes their reactions more natural as they grow older.

"Repetitive interactive activities help strengthen the bond between parents and children," Davachi shared.

According to Ms. Ghetti, although early childhood memories cannot be recalled in adulthood, experiences during this period still have a profound impact on a child's cognitive and emotional development.

"This reminds parents that the infancy period is not a blank slate. Young children are absorbing a great deal of information, and providing opportunities for them to observe and explore can play a crucial role in developing their learning skills later on," she added.

Thanh Mai (according to CNN)