Scientists from several U.S. universities, including Columbia University and Yale, have uncovered compelling evidence that memories formed in the first two years of life may be stored in the brain, even if adults are unable to consciously recall them. This groundbreaking discovery challenges long-standing beliefs in neuroscience that early-life memories simply never form due to the immature development of the hippocampus, a brain region crucial to memory encoding.
“Most people’s earliest memories date back to around age three or four, and few remember anything from infancy—even though this is a period when we learn an enormous amount about the world,” said Dr. Tristan Yates, a neuroscientist at Columbia University, in an interview with Newseria.
A Shift in Scientific Understanding
Until now, the dominant theory has been that because the hippocampus—the part of the brain responsible for episodic memory—develops slowly and continues maturing into adolescence, infants are simply unable to form lasting episodic memories. Dr. Yates and her team set out to challenge this assumption.
In a study published in March 2024 in the journal Science, Yates led a team that examined whether the hippocampus in infants is active during the formation of new memories. Prior studies had shown activity in this region for other memory types, but not for episodic memory, which records specific experiences tied to time and place.
How the Study Was Conducted
The experiment involved 26 children aged four months to two years. Researchers showed them a series of images—such as a canyon, a dog toy, and a woman’s face—then later tested their ability to recognize the same images compared to new ones from the same categories (e.g., a canyon vs. a waterfall). Throughout the process, functional magnetic resonance imaging (fMRI) was used to observe brain activity, particularly in the hippocampus.
“We hypothesized that babies would look longer at familiar images. When they did, we analyzed what was happening in their brains the first time they saw that image,” said Yates. “We found that the hippocampus was significantly more active during initial viewing of images that were later recognized. This suggests that even at such a young age, the hippocampus can form short-term episodic memories.”
The Infant Brain Is Learning—Even If We Forget
This finding offers important insight into the mystery of infantile amnesia—why adults can’t remember early-life experiences even though those experiences shaped their development. Previous research led by Dr. Cameron Ellis explored statistical learning in infants, a type of memory that identifies regular patterns in the environment—like the sequence of feeding, burping, and napping.
“Statistical learning is essential in infancy. Our earlier studies showed that even as early as three months, the hippocampus is involved,” Yates said. “In contrast, episodic memory seems to engage the hippocampus more fully around the age of one year.”
Why Can’t Adults Recall Early Memories?
Yates believes the key to understanding childhood amnesia lies not just in whether memories are formed, but in how they are stored and retrieved. Episodic memory, she explains, is relational and tied to specific times and places—more complex than simple pattern recognition.
“We focused on visual memory, but we want to study more complex memory types to see if they require more time to develop. It’s possible the memories are created but eventually lost, or they might be stored but become inaccessible over time,” she said.
The team proposes two main hypotheses:
- Memories are not properly stored or never transferred from the hippocampus to other brain areas.
- Memories are stored correctly but become inaccessible later in life.
“The second theory is fascinating—our early-life memories might still be stored in the adult brain, but the connections to access them have been lost,” said Yates.
Clues from Animal Studies
Research on rodents supports this theory. Mice that learn to navigate a maze in early life seem to forget it later, but when certain brain circuits are artificially activated, the memory re-emerges.
“In experiments, a mouse placed in a cage associated with a mild shock later appears to forget—but if specific neurons are reactivated, the mouse behaves as if it remembers,” Yates explained. “This suggests that early memories are retained but hidden, and our infant study shows a similar formation pattern, though we haven’t traced the full trajectory as with rodents. That’s something we hope to explore next.”
What Shapes Infant Memory?
Beyond neural development, Yates and her team are interested in external factors that may influence memory in infants—such as emotional intensity and interactions with caregivers. Understanding these variables could help answer the ultimate question: Do we really forget our earliest experiences, or do we simply lose the key to unlock them?
