Eli5 the brains ability to not run out of “storage”
In: 105
Imagine your brain is like a giant toy box. Every time you learn or experience something, it’s like adding a toy to the box. But instead of the box getting full, the toys (your memories and experiences) might change a bit to fit in. Sometimes they combine, become smaller, or even fade away. So, while it feels like the box has endless space, it’s more about how cleverly it organizes and manages the toys. Over time, you might not remember every single toy in detail, but the box never truly overflows.
Detail:
The brain is composed of approximately 86 billion neurons, each making thousands of synaptic connections to other neurons. The brain’s storage capacity doesn’t function like a digital storage device where there’s a fixed limit; rather, it’s a dynamic system where memory and learning occur due to changes in the strength of synaptic connections, a process called synaptic plasticity.
1. Memory Consolidation and Pruning: Memories are not stored as static ‘files’. When we first form memories, they are more vulnerable and can be easily forgotten. Over time, a process called consolidation occurs which strengthens some memories and weakens others. The brain prunes away certain synaptic connections while strengthening others. This process allows the brain to maintain more important or frequently accessed information and let go of the less important or rarely accessed info.
2. Memory Compression: The brain doesn’t store exact copies of every experience. Instead, it tends to extract the gist or main ideas, which means many details might get lost over time. This “compression” allows us to hold more information in a summarized form.
3. Neurogenesis: Even though the rate is slow and limited to certain areas of the brain, new neurons can form in the adult brain, specifically in the hippocampus, which is crucial for memory. This adds some capacity for new connections.
4. Distributed Storage: Unlike a computer which saves a file in a specific location on a disk, memories are distributed across networks of neurons. A single memory might involve multiple brain regions working together. This distributed nature allows for greater flexibility and capacity.
5. Limitations: While the brain is incredibly adaptable and efficient, it is not infinite in its capacity. As we age, cognitive decline can occur, and some memories fade or become less accessible. However, the sheer number of potential synaptic configurations means we’re unlikely to “run out” of storage in a traditional sense.
While it’s inaccurate to say the brain has unlimited storage, its dynamic and adaptive nature, combined with its number of neurons and synapses, allows it to handle a tremendous amount of information throughout your life.
Each human brain contains an estimated 100 billion neurons. Each memory is a set of specific neurons firing in a specific sequence. That leaves a lot of options and pathways for forming memories. Then add on the fact that we are constantly pruning useless memories and strengthen useful ones and suddenly the capacity expands more because we are constantly optimizing the memories which are most important which frees up neurons to remember new things.
It is estimated that the human brain can remember 2.5 petabytes of data. that’s about 300 years of continuous 1080p video.
You have a lot more storage than you imagine you do. Way more than you will ever possibly need.
And also, it regularly forgets stuff too. It screens out and throws away tons of information all the time.
Our brain is NOT like a video camera that’s always on, storing a perfect record of what has happened. It is still a big open question of how we store information, but we do know that the brain is very efficient at using the same regions to encode many pieces of information.
One way it does this is breaking the information apart into ‘features’ and building up information/knowledge out of common features. Like it doesn’t store ‘red’ separately for every red object, it just links to the same feature ‘red’ when it encodes different memories with that feature. Do this for a whole bunch of features (including basic sensory ones but also more complex concepts/thoughts/emotions/etc.) and you can encode HEAPS just by recombining the same features.
Another way it does this is by being selective in what it takes in. We’re not built to take in a ‘perfect record’, we’re likely built to take in what is useful to our lives and goals (or what has been useful through our evolutionary history). So anything related to our safety, belonging, health, interests, or anything that we experience repeatedly is more likely to be stored as ‘knowledge’ in our internal model of the world.
A final note is that our brain likely builds a ‘predictive model’ of the world, based on our past experiences. This means that when we experience things, we’re not taking in all the information from scratch, we’re already living in our ‘mental model’ and the new sensory information is just updating that model. That means when there’s a ‘good enough fit’ between incoming information and our mental model, our brain isn’t doing much work to store anything new, it’s basically just going ‘yup, fits the model’. When there’s a mismatch or surprise between what we experience and our mental model, then it updates the model. That means we’re not storing every incoming piece of information separately, we’re just continually building on our existing internal models of the world.
In movies they have those evidence boards with different pieces of evidence connected each other with strings. The brain is kind of like that. In ELI5 terms, you can imagine each neuron as an “evidence”, when a new memory is made, strings are attached from one evidence to another, to make a story. Strings in this analogy are the connections that neurons make with each other.
You brain does not run out of space as it stores memories as these connections, and similar to how you can always add more strings to the evidence board, your brain can make new connections.
The caveat however is that, connections that are not reinforced can be forgotten (a better explanation is that the connection is not forgotten or lost, but the existence of that connection is forgotten). With the evidence board analogy, you can think of this like constantly adding new strings to the board. At some point, there will be so many strings in the board that they will start to block each other, and you won’t be able to see the connections at the back. The connections are still there, and if you dig through the strings you can reveal them, but will take some effort to find where they lead to. If you think those connections are important, you can move those strings to the top, which is similar to what your brain does when a memory is reinforced.
Imagine taking a photo of a single tree with a very good camera. You can see all the details of that tree, the bark, the leaves, maybe bugs.
Now move back, and with same camera take a picture of 20 trees. You can’t discern as many details, but you now have more objects and they still fit into the same size of photo.
Move back more, take picture of a forest. All trees kind of look the same now, some taller, some shorter maybe. But you have so many! All fitting into same photo size.
This is approximately how brain works. The more information you put into it – the more it generalizes it, by omitting details mostly, this being able to fit it all into same set of neurons.
It’s not that it *can’t* run out. It’s that no one has ever lived long enough to seriously tax it.
I have no idea how long that is, but physics says there must be a limit to how much data a given amount of matter can encode. I would guess that it would take the form of older memories fading, rather than becoming unable to create new ones, since that already happens as we age anyway.
I can’t answer your question directly OP but I can give you a explain like you’re ten answer in saying that the Brain actually does have a storage limit.
That storage limit would be equivalent to the amount of data you’d have if you had a TV with a 24/7 television program and set a DVR to record said TV Chanel/program for 300 years straight with no breaks.
That’s roughly how much data the human brain can store before we would actually start to “run out of room”
I don’t know, I feel like mine is getting full enough that the idea of living much longer than a typical lifespan seems intolerable.
Remember that time I took a home wine-making course and forgot how to drive?
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