Do you remember anything before the age of two? Few, if any, of us can. However, anyone with a child or who interacts with small children knows that babies can form memories. They can tell their parents apart from a stranger, recognize familiar places, and pick out their favorite toys. Before they can speak, babies are learning and forming memories. It is not surprising that even our pets have memories and preferences.

Studying the memory of someone who cannot tell you what they remember, like a baby, is not easy. What makes it more challenging is that those memories are lost as we get older. Now, a groundbreaking study from Harvard University has captured signs of early memory formation in babies as young as three months old. Understanding how babies learn and remember may help answer the age-old question of why we forget being babies.

Early Brain Development

How the brain develops in the first years of life shapes how we learn, think, and remember. During these early years, the brain forms millions of new connections every second. These connections are the building blocks for everything from language to emotional regulation to memory. As the brain continues to develop, certain areas become specialized. This lays the groundwork for creating more complex memories that allow us to recall events, places, and emotions tied to those experiences.

The brain’s memory center, the hippocampus, seems to be active earlier than we previously thought. From as early as three months, MRI brain imaging has uncovered changes in the hippocampus associated with learning and memory. This suggests babies might be taking in more than we realize, even in those early months.

Inside a Baby’s Brain

Babies are naturally curious and restless, so imaging their brains while they are awake is not easy. In their study, the Harvard team used a mix of sounds and visuals to keep the babies still long enough to capture a picture of their brains. While inside the scanner, the babies were shown a series of images, like a toy or a scene from nature. Each image appeared for two seconds in front of a moving psychedelic background to hold the baby’s attention. After they had seen all the images, the babies were then presented with two images at a time: one of the previous images and a new image. The team anticipated that the babies would spend more time looking at the image that they remembered.

While there was no difference in how long the babies looked at either image, the team observed that the brain responded differently to familiar vs. new images. Using the images that they recorded from the MRI scans, they were able to measure changes in the brain’s blood oxygen levels. Higher blood oxygen in a certain area means that those neurons are more active.

What they found was that there was a burst in activity throughout the hippocampus when the babies were looking at familiar rather than new images. The more familiar the object seemed, the more blood oxygen was measured. This was especially apparent in those between one and two years old compared to infants below the age of nine months. These findings seem to suggest that babies begin to encode episodic memories, that is, memories of past experiences, at around one year. Even before then, neurons in the hippocampus are active and making new connections.

Where do the memories go?

Most people remember very little, if anything, from their early childhood. What happens to the memories that we form as babies? This is what is known as infantile amnesia. There are a few theories about why this happens. One of the main reasons is that parts of the brain responsible for long-term memory, like the hippocampus, are still being developed in the first years of life. While the brain may be taking in and encoding new information, these areas are not ready to store those memories in such a way that we can recall them later in life.

It may also be that babies do not have the words or concepts to represent their experiences. As we get older and start developing language, we can better organize and make sense of our memories. Without a “story” to represent memories, it becomes harder to remember things that happened a long time ago.

Other theories suggest that it may have to do with how quickly the brain changes from birth. Despite the millions of new connections being formed, those that are not used or reinforced are later discarded. This “pruning” process allows the brain to work more efficiently but may also lead to the loss of early memories.

Conclusion

Babies do remember; where those memories go remains a mystery. The findings from this study have sparked new questions to explore about learning and memory. As we dive deeper into how the mind of a baby works, there is a lot more to discover about the early stages of memory development and how those early experiences shape who we become later in life.