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Think back to your very first memory. Maybe it is a flash of a yellow toy, the scent of a particular rug, or a blurry face leaning over a crib. For most of us, there is a hard “blackout” before the age of three or four.
Scientists call this infantile amnesia. For decades, the leading explanation was pretty straightforward: babies simply did not have the hardware yet. We assumed the hippocampus, the brain region that files away our life experiences, was not “online” enough to record specific events.
A recent study published in Science is pushing back on that idea. The librarian, it turns out, was at her desk the whole time. She just filed everything in a system that, by the time you came looking, had been completely reorganised.
Scanning the “Awake” Infant
Studying the infant brain is notoriously tricky. You cannot exactly ask a ten-month-old to lie still while you slide them into an fMRI machine.
But researchers pulled off something pretty clever. They scanned the brains of 26 awake infants while the babies looked at photos of faces, objects, and scenes. Hours or even days later, they tested the infants’ memory the only way you really can with babies: by checking whether they stared longer at the familiar “old” photos than at new ones. Babies naturally fixate on things they recognise, so this tells you something real about what stuck.
The Librarian Wakes Up
What they found surprised a lot of people. In infants around one year of age, the hippocampus lit up noticeably when a baby first encountered an image. And crucially, that activation predicted whether the baby would recognise the same image days later.
A few things stood out:
- The capacity to lock in these one-shot memories seemed to come online right around the first birthday.
- The activity was strongest in the back part of the hippocampus, the so-called posterior region. In adults, this same area handles something called pattern separation: the ability to tell apart two memories that look almost identical.
- Put together, this tells us that the absence of early memories is probably not about a recording failure. The brain was capturing things. The problem lies elsewhere.
Where did the files go?
So if a twelve-month-old is busily recording their life, why cannot the grown-up version of you play it back?
The researchers think infantile amnesia is more of a retrieval problem than a storage one (though it may well be a bit of both). Here is one way to picture it. At age one, your brain was writing files. But it was also growing at a furious pace, rebuilding its connections almost constantly. The old paths to those early memories got buried under all that new wiring. The files might still be there, somewhere, but the search function no longer finds them.
Why this actually matters
If your brain was actively recording the world at age one, those early experiences were not simply wiped. They shaped the person you became.
Think of it a little like the gut bacteria we talked about last time: invisible, inaccessible, but quietly doing something important. That inexplicable comfort from a particular piece of music, or the vague unease that a certain smell triggers for no reason you can name, may have roots in a memory you can no longer reach.
Memory is not really a photo album you flip through at will. It is more like the ground beneath a city: you cannot see it, you cannot get to it, but without it nothing above stays standing.
You might not remember being one year old. Your hippocampus does.
Credits
Auteur: Amir Homayun
Buddy: Siddharth
Redacteur: Lucas
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