What is the earliest memory you can remember? While many people’s memories of the past may go back to childhood, research shows that when they reach childhood, lanes of memories generally hit walls. In a way, this doesn’t make much sense. After all, the first year of a baby’s life is learning basic psychological concepts, forming relationships with the caregiver, and gaining a sense of self.
Experts have long attributed this “infant amnesia” to the development timeline of the hippocampus, a region of the brain that holds memories. However, new evidence from Yale teams suggests that early explanations of memory blocks may be a little more complicated. Humans produce memories during the first few months of life, where do those memories go?
The researchers detailed their work in a study published in the journal on March 20th Science. To begin the experiment, scientists showed the infant a series of new images and then tested them later to see if they remembered it. Recognizing past images is an example of episodic memory. As adults, these can take the form of reminiscing about a particular event, such as watching sports games or taking vacations. However, if there is a rather obvious communication barrier between adults and many babies, it is more difficult to judge the memory ability of an episode.
“Features [episodic memories] Nick Turk Brown, professor of psychology, director of the Yale-u-Tsai Institute and senior research author, says that it means you can explain them to others, but that’s off the table when dealing with a toddler of words.
Instead of learning BabyTalk, the team recorded hippocampal activity during both trial stages using functional magnetic resonance imaging (fMRI). Results showed that if the hippocampus was more active during the initial exposure, it appears that the infant would likely remember the image. They also looked up the baby’s physical cues for further confirmation.
“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.”
The infant’s behavior corresponded to their fMRI scans. While looking at the image first, the more active hippocampus meant that the baby saw it longer when he later saw it again. Meanwhile, the posterior portion of the illuminated hippocampus is the same region associated with the temporary memory bank of adults. The most powerful evidence shows a timeline of how the brain develops in these first few years, born from an infant over 12 months of age.
Previous work by the Turk-Browne team It’s already revealed Babies show what is known as statistical learning even earlier. Although there is a peculiarity in episodic memory, statistical learning is related to more holistic concepts, such as understanding what buildings look like and which traditions are celebrated on a particular holiday. Each also depends on separate neural pathways in the hippocampus. In combination with the latest findings, researchers have a better understanding of the progression from early statistical learning formation in babies to the development of episodic memory. According to Turk-Browne, this makes a lot of sense.
“Statistical learning is about extracting the structure of the world around us. This is important for the development of language, vision, concepts, and so on,” he said. “So I understand why statistical learning is played faster than Episode Memory.”
But the bigger question still remains: what will happen to these earliest memories? Turk-Browne believes there are multiple possible explanations, including the theory that these recollections simply never reach the long-term storage area of the brain. However, senior research authors believe that another reason is more likely. These memories remain encoded in the brain, but we simply can’t access them. That’s what the team wants to explore in the future.
“We are beginning to track the durability of hippocampal memory throughout childhood and entertain the possibility that we cannot withstand adulthood in any way, and in most ways,” Turk-Browne says.
