Why Can’t We Remember Being Babies? Yale Study Sheds Light on Infantile Amnesia

Why Don’t We Remember Being a Baby? New Study Offers Insights into Infantile Amnesia

It’s a question that has puzzled scientists and parents alike for years: why can’t we remember events from our earliest years of life? We go through an immense amount of learning during our first few years, acquiring language, motor skills, and forming the foundation of our understanding of the world around us. Yet, as adults, we have no memory of those events. This phenomenon, known as “infantile amnesia,” has long been attributed to the developmental immaturity of the hippocampus, the part of the brain responsible for storing memories. However, a new study by researchers at Yale University challenges this long-standing assumption, providing fresh clues that may finally explain how and why we fail to retain memories from our infancy.

The Traditional Explanation: Immature Hippocampus

Historically, scientists have argued that the hippocampus, which plays a central role in encoding and retrieving memories, is not fully developed during early childhood. As a result, it has been assumed that infants simply don’t have the ability to form lasting memories during the first years of life. This hypothesis aligns with the general understanding that the hippocampus continues to mature well into adolescence, making it difficult, if not impossible, for babies to form memories that endure.

But new research challenges this idea, suggesting that infants may, in fact, be capable of encoding memories during their early months—contradicting the notion that the hippocampus is entirely underdeveloped in infancy.

Yale Study Reveals New Insights into Infant Memory Formation

A groundbreaking study led by Yale researchers, and published on March 20 in Science, sheds new light on how memory formation might occur in infancy. The research team conducted experiments to test whether infants can form and retain episodic memories, which are memories of specific events or experiences. In the study, researchers showed infants—ranging in age from four months to two years—new images, such as faces, objects, or scenes. Later, they tested whether the infants could recognize these images after being shown new ones.

This experiment revealed that when an infant’s hippocampus was more active upon seeing a new image for the first time, they were more likely to recognize that image when it reappeared later. The stronger the hippocampal activity, the longer the infant gazed at the previously shown image, which the researchers interpreted as a sign of recognition. These results suggest that infants do, in fact, have the capacity to encode and retain memories in their hippocampus from a much earlier age than previously thought.

The Role of the Hippocampus in Memory: From Statistical Learning to Episodic Memory

To better understand these findings, it’s important to consider the different types of memory that exist. The hippocampus is involved in two distinct types of memory: statistical learning and episodic memory. Statistical learning, which is typically observed in younger infants, involves extracting patterns from experiences, such as identifying repeated sequences or associations in the environment. This type of learning is essential for the development of language, visual perception, and even basic concepts.

Episodic memory, on the other hand, is more complex and involves the recall of specific events or experiences. It’s the kind of memory that allows us to remember a birthday party from our childhood or the details of a family vacation. Episodic memory is typically associated with the posterior part of the hippocampus, an area at the back of the brain that becomes more active as infants age.

In previous studies, the research team had already demonstrated that infants as young as three months old are capable of statistical learning. However, they suspected that episodic memory—the kind that allows us to recall specific events—emerges around the one-year mark, as the posterior hippocampus begins to mature. The new study confirms this theory, showing that older infants (12 months and older) display stronger hippocampal activity related to episodic memory encoding.

What Happens to Infant Memories?

While this research sheds light on how memories are formed in infancy, it leaves us with a lingering question: why can’t we remember those early memories as adults? The phenomenon of infantile amnesia—our inability to recall specific memories from infancy—remains a mystery, despite the evidence that memory encoding begins early.

There are a few theories about what might happen to these early memories. One possibility is that the memories are not consolidated into long-term storage, meaning they simply don’t last long enough to be recalled later in life. Another possibility is that these memories are stored but remain inaccessible to us as adults. In other words, the memories might persist, but we cannot retrieve them. Turk-Browne, one of the study’s senior authors, suspects that it’s the latter: that these early memories are stored but fade over time, becoming less accessible as we grow older.

As part of their ongoing research, Turk-Browne and his team are exploring whether infants, toddlers, and children can remember home videos of themselves as babies. Preliminary results suggest that these memories may endure until preschool age before fading. This raises the possibility that memories formed in infancy could remain stored in the brain, waiting for some form of retrieval that, for reasons still unknown, never happens.

The Connection to Adult Memory

While it’s tempting to view infantile amnesia as a simple gap in our ability to remember, this research suggests that the issue may be more complex. In fact, there is growing evidence from animal studies that infantile amnesia is not necessarily a problem with memory encoding, but rather a difficulty with memory retrieval. This aligns with the findings of the Yale study, which points to the possibility that early memories may be encoded and stored, but remain elusive because the brain’s retrieval mechanisms are not yet fully developed.

The implications of these findings extend beyond understanding infantile amnesia. They suggest that memory formation and retrieval are far more intricate processes than previously realized, with the potential for long-lasting impacts on how we understand brain development, learning, and the ability to retain memories throughout life.

Conclusion: Uncovering the Mysteries of Early Memory

The recent Yale study marks a significant step in unraveling the mystery of infantile amnesia. It challenges the traditional view that infants cannot form lasting memories and provides compelling evidence that the hippocampus can encode memories at a much earlier age than we once thought. This discovery opens up exciting new avenues for research into memory development, neuropsychology, and brain maturation.

While we may not have definitive answers yet regarding why we cannot remember our earliest experiences, the growing body of research suggests that these memories may persist in some form, hidden deep within our brains, waiting for the right conditions to be accessed. This insight into how memory works in infancy could eventually lead to a deeper understanding of how memory functions throughout our lives, from infancy to adulthood.

Learn more: https://www.science.org/doi/10.1126/science.adt7570