eli5 How does the brain store information?


Like what is the unit or language? What is the mechanism of reading, writing or recalling a piece of information.

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We have no idea.

It seems like it’s through a sequence of different neurons firing. But we really don’t know.

We barely know what parts of the brain control what parts of our bodies or have what parts of thinking.

We don’t really know how it works on the very lowest level

The leading theory as of what I’ve gathered is something called Theta waves that generate Theta rhythms.

The brain can be measured by its activity levels with its frequencies it produces.

The list of them from highest frequency to lowest is Gamma, Beta, Alpha, Theta, Delta.

Gamma is your max concentration and activity level of your brain.

Beta is your average concentration and activity levels.

Alpha is your relaxed and passive attention.

Theta is deeply relaxed and inner focused.

Delta is sleep.

These waves can create rhythms like a beat of a song that’s a response from external stimulus (outside the brain). These beats are what we are currently experimenting with on humans to study how they affect our brains ability to recognize familiar senses and memories.

A study done on rats found that if you mess with the prefrontal cortex (the part of the brain behind your forehead) you can make the brains filter so to speak unable to identify past patterns and experiences.

This handshake of information between the prefrontal cortex and the rest of the brain is a major element of memory. The cortex doesn’t tell the brain what the right memories are it stops the wrong memories from intruding. It’s a major stepping stone in the researching more about schizophrenia, where a patient can recall memories correctly but cannot stop false memories or ideas from coming in. It’s where some of the people with this disease can hear voices or see things that aren’t even real.

There is still a lot to be learned and I’m sure that others can add more or correct me where I messed up. Here is an article talking about that rat study if you wanna read up on it.


Brains store information as patterns of connections between neurons. It’s kind of like an address to get somewhere, but it’s not the address itself that matters, it’s the route you take. If something matches, if there are a lot of nerves firing, the connected nerves downstream are more likely to fire, too. If it doesn’t match, they are less likely to fire.

For example, you’re looking at something. Your retina is activated in a certain pattern, and that pattern goes through your optic nerves to your brain. That activates a specific pattern of nerves in your cortex, which are all connected in very complicated ways. More nerves in your retina fire at two specific places in your field of vision which means the neurons connected to those are more likely to fire. That triggers neurons down a cascading pathway that matches the same pathway that always triggers when you’re looking at a face. Those two points are *eyes*.

You know they’re called “eyes” because when you were a child, that pattern of nerves in your retina were firing at the same time that nerves in your ears were firing in a pattern associated with air vibrations from someone saying the word “eyes.” That happened a lot, so that connection was reinforced. Whenever the retina fires like that, the pathway gets triggered that leads to the same pathway triggered by the sound “eyes” – which also triggers the pathway normally triggered by seeing the letters E Y E S.

Since you’re looking at a face, the path also leads to the area of your brain dedicated to recognizing individuals. They’re brown eyes – that means neurons for brown eyes continue to fire, but neurons for blue eyes don’t. A particular nose shape makes the path fire in *this* direction and the mouth goes in this other direction. Each connected neuron may or may not fire, until the only neurons that *do* fire are the ones associated with the face for Geoff. You’re looking at Geoff.

Because you’re looking at Geoff, that encourages certain neurons to fire that lead to episodic memory. Events that involved Geoff are more likely to fire, and some of them do, including maybe learning his name, or the last time you saw him.

Maybe the firing of neurons peters out there, and you’re done remembering about Geoff. Thinking, “I want to remember more about Geoff” sort of boosts the signal going into the episodic memory. The pathway of neurons continues to fire as connections continue to be made.

This is all very reflexive and recursive. Maybe the “face” pattern isn’t strong enough to continue firing down that path but it still tries to go down other paths, some of which lead back to the “face” path but with a stronger signal this time. “Eyes” leads to “nose” which leads back to “eyes” and they both lead to “mouth” which reinforces the signal to “face” which leads *back* to eyes and mouth and nose. The pattern is also very strong for “metal” and “glass” and “lights” so eventually the “face” signal diminishes until its gone, but that other signal is still very strong. Oh hey, it’s not a face it’s the front of a car which often sort of looks like a face…

> Like what is the unit or language?

Not sure what you’re expecting with “language.”

In the most general terms, information is stored in nervous systems through various changes to neurons (and maybe also to glial cells). Those changes can include changes in either intrinsic properties (firing patterns, excitability, cellular structure, etc.) or synaptic connections (strength, reliability, wiring diagram, etc.).

Both “writing to” (aka learning) and “readout” (aka recall) require specific neuronal activity.

There are many mechanisms that are studied.

One well studied example is Hebbian learning, often cutely summarized by “Neurons that fire together wire together.” “Fire” here means have a sudden, large, well-studied change in the neuron’s electrical “pressure” (voltage). This means that if a neuron A participates in getting another neuron B to fire, that connection between A and B is strengthened–meaning it will be even more likely to successfully participate in getting B to fire in the future.

Do that many times–through practice–and you can begin to really “tune” a set of connections. That is one kind of storage of information. If you’ve ever learned a physical pattern, like a musical scale on an instrument, you’ve probably marched some neurons through their Hebbian paces.

That said, we know a great deal about such changes and yet there is a tip of the iceberg effect. What we can’t say in 2023 is exactly how a person’s brain changes to learn a new foreign language word, for example. That’s a tall order.