Research finds evidence that infants can encode memories in their early life

Although we learn a lot during the first year of our lives, as an adult, we cannot remember certain events of that era. Researchers have long believed that we are not holding these experiences because the hippocampus, a part of the memory-saving brain, is still well developed in adolescence and cannot encode memories in our early years. However, new Yale research finds evidence that it is not the case.

In the study, Yale researchers showed young children new images and later tested whether they remembered them. When infant hippocampus became more active when they first saw the image, they were more likely to appear to recognize the image later.

The survey results were published on March 20th Science, It shows that in the first few years of our lives, memories are actually encoded in our brains. And now researchers are looking at what happens over time in those memories.

The inability to remember certain events in the first few years of life is called “infant amnesia.” However, this phenomenon is difficult to study.

The characteristic of these types of memory we call episode memories is that you can explain them to others, but that's off the table when you're dealing with pre-verbal infants. ”

Nick Torque Brown, professor of psychology at Yale's Faculty of Arts and Sciences, director of Yale's Woo Tsai Institute, senior author of his research.

For this study, researchers wanted to identify robust methods for testing temporary memory in infants. The team led by then graduate student and now a postdoctoral researcher at Columbia University, Tristan Yates used an approach that showed new faces, objects, or scenes for infants between four months and two years. After that, after the infant saw several other images, the researchers showed previously seen images next to the new image.

“When the baby sees something previously, we hope they see more of it when they see it again,” Turk Brown said. “In this task, if the toddler is staring at a previously seen image more than the new one next to it, it can be interpreted as the baby perceives it as familiar.”

A new study has pioneered methods for performing functional magnetic resonance imaging (fMRI) with awake infants over the past decade (has historically been difficult because infants have short attention spans or cannot continue in a direction).

Specifically, the researchers evaluated whether hippocampal activity is related to infant memory strength. They discovered that the greater hippocampal activity when infants are looking at new images, the longer they see it when the infant reappears later. The posterior part of the hippocampus (near the back of the head) where encoding activity was most intense, is the same region that is most associated with adult episodic memory.

These findings were true across a sample of 26 infants, but were the strongest among infants over 12 months (half of the sample group). This age effect leads to a more complete theory of how the hippocampus develops to support learning and memory, Turk-Browne said.

Previously, the researchers found that the hippocampus of a young 3 month old infant exhibits a different type of memory known as “statistical learning.” While the memory of the episode deals with certain events, such as sharing Thai meals with out-of-town visitors last night, statistical learning is to extract patterns across events, such as restaurants that look like restaurants, specific dishes found or typical appearances where they are served seated.

These two types of memory use different neuronal pathways in the hippocampus. And in previous animal studies, researchers have shown that statistical learning pathways occur where the anterior part of the hippocampus (close to the front of the head) develop faster than that of episodic memory. Therefore, Turk Brown suspected that memories of the episode could appear in early childhood for about a year or more. He argues that this developmental progression makes sense when thinking about infant needs.

“Statistical learning is about extracting the structure of the world around us,” he said. “This is important for the development of language, vision, concepts, etc., and so I understand why statistical learning is played faster than episodic memory.”

Still, the researchers' latest research shows that episode memories can be encoded by the hippocampus earlier than previously thought long before the earliest memories that can be reported as adults. So what about these memories?

There are several possibilities, Turk-Browne says. One is that it simply doesn't last long as it may not convert memory into long-term storage. The other is that memories are there ever since they were encoded and they are inaccessible. And Turk Brown suspects that it could be the latter.

In the ongoing work, Turk-Browne's team is testing whether to remember home videos from toddlers, toddlers and children filmed as (young) babies.

The new findings led by Yates provide important connections.

“Tristan's work in humans is highly compatible with recent animal evidence that infant amnesia is a problem of recovery,” Torque Brown said. “We are beginning to track the durability of hippocampal memory throughout childhood and entertain the possibility of radical science fiction that may somehow not bear adulthood.”