Researchers discover why people don’t remember being a baby

For decades, scientists have been puzzled by a simple question: Why can't you remember being a baby? Even though infants learn rapidly in their early years, most people can't recall anything from before age three. This common phenomenon, known as infantile amnesia, has led researchers to debate whether babies fail to form memories or if they simply forget them over time.

Recent research challenges the idea that early memories don’t exist. A groundbreaking study from Yale University suggests that infants’ brains do encode experiences, but these memories might become inaccessible as the brain matures. The findings reshape our understanding of memory formation and could provide clues about how memory retrieval works later in life.

The hippocampus, a small seahorse-shaped structure deep in the brain, plays a major role in forming and retrieving episodic memories—those tied to specific events, places, and people. In adults, damage to the hippocampus leads to severe memory loss, making it difficult to recall personal experiences. Scientists have long debated whether an infant’s hippocampus is developed enough to encode these types of memories.

Earlier theories suggested that the infant hippocampus was too immature to store episodic memories. This idea was based on the fact that the brain’s memory circuits, known as the trisynaptic pathway, are still developing in early life.

Some studies also compared infant memory capabilities to adults with hippocampal damage, reinforcing the belief that young brains couldn't encode experiences properly.

However, newer research suggests otherwise. Behavioral studies have shown that infants can remember specific events for days, weeks, or even months, contradicting the idea that their brains can't store memories. But until now, direct evidence from the brain itself was lacking.

In the latest study, published in the journal Science, researchers used functional magnetic resonance imaging (fMRI) to measure brain activity in infants aged four to 25 months as they viewed images of faces, objects, and scenes. By analyzing how long infants later looked at familiar images compared to new ones, scientists could determine whether a memory had been encoded.

The results showed that when the hippocampus was more active during an image’s first appearance, the baby was more likely to recognize it later.

The findings suggest that infants as young as 12 months can encode episodic memories in the same region of the hippocampus that adults use for memory storage. Specifically, activity in the posterior hippocampus—the part closer to the back of the head—was linked to stronger memory encoding. This region is also crucial for adult episodic memory, reinforcing the idea that infants' brains use a similar mechanism.

However, younger infants showed a different pattern. Babies under 12 months didn't display the same memory-related brain activity, suggesting their hippocampal circuits were still developing.

These findings align with past research on statistical learning, another type of memory that helps infants recognize patterns in their environment. This form of learning, linked to a different hippocampal pathway, emerges earlier than episodic memory and helps babies understand language, objects, and social cues.

“The hallmark of these types of memories, which we call episodic memories, is that you can describe them to others, but that’s off the table when you’re dealing with pre-verbal infants,” explained Nick Turk-Browne, senior author of the study and professor of psychology at Yale.

By showing that the infant hippocampus can encode memories, the study shifts the focus from whether babies can store memories to why they forget them.

If infants can encode memories, why don’t you remember being a baby? Researchers believe the answer lies in how memories are stored and retrieved over time.

One possibility is that early memories never transfer to long-term storage, fading before they can be solidified. Another explanation is that these memories remain in the brain but become inaccessible as it develops.

Animal studies provide intriguing clues. Research on rodents shows that memories formed in infancy leave lasting cellular traces, called memory engrams, in the hippocampus. Even when young animals appear to forget, these traces remain intact. In some cases, memory recall can be restored through specific cues or direct stimulation of these engrams.

Interestingly, the rapid neurogenesis (growth of new neurons) that occurs in infancy may interfere with memory retrieval. Some scientists believe that as new neurons integrate into the hippocampus, they disrupt existing memory circuits, making earlier memories harder to access. This could explain why memories from early childhood fade even though the brain is still capable of storing them.

Turk-Browne and his team are now testing whether infants, toddlers, and preschoolers can remember experiences from their own babyhood. Preliminary results suggest that some of these memories might persist into early childhood before eventually becoming inaccessible.

“Tristan’s work in humans is remarkably compatible with recent animal evidence that infantile amnesia is a retrieval problem,” Turk-Browne noted, referring to lead researcher Tristan Yates.

The new findings challenge the traditional view that infantile amnesia occurs because the brain is too immature to form memories. Instead, they suggest that early memories are encoded but become difficult to retrieve as the brain develops. This could have broader implications for understanding memory disorders, childhood development, and even memory enhancement techniques.

Future studies aim to track memory development across early childhood, identifying the key factors that influence long-term memory retention. If scientists can determine why early memories become inaccessible, they may uncover ways to improve memory retrieval later in life.

The study also raises a fascinating question: Could forgotten infant memories still exist somewhere in the brain? While retrieving them remains a challenge, ongoing research may one day reveal whether these lost memories are truly gone—or simply hidden away, waiting to be unlocked.

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