Mar 27, 2025 08:30:00

Infant brain scans reveal when humans start forming memories

Most people have difficulty retaining memories from before the age of three, a condition known as '

infantile amnesia .' Infantile amnesia does not mean that people have no memories from before the age of three, but rather that memories are difficult to consolidate before the age of three. However, by scanning the brains of infants with magnetic resonance imaging (MRI), it has become clear when humans begin to form memories.

Hippocampal encoding of memories in human infants | Science
https://www.science.org/doi/10.1126/science.adt7570

Brain Scans of Infants Reveal the Moment We Start Making Memories
https://singularityhub.com/2025/03/20/new-baby-brain-scans-reveal-the-moment-we-start-making-memories/

The hippocampus , part of the limbic system, is an extremely important organ for human memory. It has been shown that damage to the hippocampus can cause memory disorders. However, because the hippocampus is still developing during childhood, scientists have believed that the hippocampus is too immature for infants to form memories.

'It's not that we have no memories of infancy at all,' said memory researcher Nicholas Turk Brown. 'In fact, that's the time when we're learning language, learning to walk, learning names for things, and forming social relationships. How can we remember nothing from a time like that when we're learning so much?'

Decades of research into memory have established that the hippocampus is responsible for

episodic memory , which allows us to remember things like who we met at a party, where we parked our car, or what we had for dinner three days ago.

All of our everyday experiences are encoded on neural connections in the hippocampus, where a group of neurons called memory engrams captures different memories and keeps them separate so they don't mix up with each other.

Once the brain encodes information, it converts important memories into long-term memories during sleep. Studies of rodents and humans who sleep after learning a new task have shown that the hippocampus in the brain is more active during a night's sleep, and memory performance improves after sleep.

The memory is then recalled by 'recalling' the memory that has been stored in the brain in this way. However, if any of the steps in the process of memory storage described above fail, it will not be possible to recall the memory correctly.

A research team from Columbia University and Yale University conducted an experiment in which they scanned the brains of 26 infants aged 4 to 25 months with MRI while they performed memory tasks. Specifically, they used functional

MRI , a method of visualizing the hemodynamic response associated with brain activity, to measure brain oxygen levels and investigate local neuronal signaling.

In addition, because previous research has shown that infants 'prefer to gaze at previously seen objects or images rather than new objects,' the research team prepared 'photos that the infants had seen before' and 'new photos that they had not seen before' and monitored the infants' eye movements.

The research team was able to measure the oxygen levels in the hippocampus for an average of about 8 minutes per subject. As a result, it was revealed that the oxygen levels in the hippocampus increased rapidly when infants looked at pictures they had seen before. However, this was not the case for all infants, and no rapid increase in oxygen levels in the hippocampus was detected among infants under the age of one.

In addition, while infants over one year of age looked more intently at familiar pictures than at new pictures, children under one year of age did not show any preference for either 'new' or 'familiar' pictures. This suggests that children begin to encode memories around 12 months of age.

These results do not indicate that infants are able to acquire rich memories from around the age of one. However, further research into memory and the hippocampus may shed light on details about childhood amnesia.