Babies as young as one year old can form memories, according to the results of a brain-scanning study published today in Science¹. The findings suggest that infantile amnesia — the inability to remember the first few years of life — is probably caused by difficulties in recalling memories, rather than creating them.

“One really cool possibility is that the memories are actually still there in adulthood. It’s just that we’re not able to access them,” says study co-author Tristan Yates, a neuroscientist at Columbia University in New York City.

Memory mystery

Try as we might, adults can’t remember events from our earliest months or years. But whether this is because a baby’s hippocampus, a key brain region in storing such memories, is not sufficiently developed or because adults cannot recall these memories has long been an open question.

To shed light on the issue, Yates and her colleagues used functional magnetic resonance imaging to scan the brains of 26 young children, aged 4 months to 2 years, who were performing a task involving memory.

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The team measured hippocampal activity as the children viewed an image of a new face, object or scene for 2 seconds, and when they were shown the same image again about a minute later.

They found that the greater the hippocampal activity when a baby was looking at a new image, the longer they looked at that image when shown it again. Because babies tend to spend more time looking at familiar things, this result suggests that they were remembering what they had seen.

The researchers saw the strongest encoding activity in the posterior part of the hippocampus — the area most associated with memory recall in adults.

“What this study shows is a proof of concept that the encoding capability exists,” says study co-author Nick Turk-Browne, a cognitive psychologist at Yale University in New Haven, Connecticut.

“Although we saw this across all the infants in our study, the signal was stronger in those older than 12 months of age, suggesting a kind of developmental trajectory for the ability of the hippocampus to encode individual memories,” says Yates.