I have been to some interesting places in my own brain with the help of psychedelics. While I have experienced different levels of self-awareness, the possibility of that “filling up my brain” is likely not possible.
There is a part of the brain that psychedelics specifically affect that functions as kind of a traffic regulator. It typically only directs signals from one part of the brain to another part. Psychedelics open these pathways up and allow for information to flow to in all kinds of directions. (Synesthesia, sensory confusion, is an example: Feeling colors and seeing sounds.)
What the experience does for me, is that I seem to gain more awareness into how my brain works. It’s like I can stand back and watch how my brain processes things. My subconscious is pulled into full view and I can almost tinker with it, in a way. Some theories suggest that the colors and geometric patterns people tend to see is our actual brain operations being leaked into the visual cortex and/or the fractal patterns are the result of actual “data loops” caused by psychedelics allowing information to pass around freely. (Not my theories, btw.)
Now, you may read this and think: That dude is just tripping! (And you would be very much correct.) The thing is, every experience I have and anything that I feel is already in my brain. The data is already there, but how that data is processed is vastly different. Even if I am perceiving parts of my brain that I couldn’t before, it’s still just the same neurons that were always there.
So, what I am basically saying is, is that my self-awareness temporarily becomes self-aware. It’s a shitty description, but it’s the closest I could get to matching the situation you were asking about.
I still develop memories, almost as normal. Some memories stick and some fade. All that really happened is that a few neuron weights got shaken up and it all becomes a few new pathways with a similar number of neurons as before. (Neurogenesis and dendritic growth as a result of psychedelics is a different subject and I wouldn’t think it would be part of the recursion-type situation you are asking about.)
Memories become integrated with existing ones, basically. While vastly different in many ways, our current AI tech has a set number of “neurons” it can work with in any given model. You can train those same bunches of neurons with millions of different patterns, but the actual size of the neural network doesn’t change, no matter how much data you cram into it. With slight changes to when neurons fire, you are using specific pathways of neurons to save data, not necessarily using the neurons themselves.
False perspectives, sure. That is a possibility. False or not, that reasoning forms memories which must be stored somewhere. Those memories are what you might consider “new data” that comes from “new connections”.
Understanding something is based off what you already know or just learned, which is memory. Logic and reasoning is partially instinctual and mostly memory. Decision making is likely not strictly based in memory, but more based on memories.
I think where you might be getting something mixed up is undersanding vs. memorizing and how the brain stores information. If I am understanding you correctly, you are thinking of data like a computer handles data: A zero or a one is a bit. Eight bits are in a byte. PC memory can hold X bytes until it gets full, and then game over.
Our brains simply don’t work like a PC and we naturally store patterns, not specific raw data.
So, if a neuron has 3 inputs and 3 outputs, it has 6 connections to other neurons. With a computer, you need to lay out a few arrays and map each connection to each other. If we had a mess of neurons on a table in front of us to stick together, we would just need to remember to connect outputs to inputs and follow any other simple conditions we are given without strictly needing to memorize a 1:1 connection map.
Pattern matching is core functionality for our brains. So much so, we actively seek out patterns whenever we can. (Reference: apophenia and pareidolia)
For things like simple number memorization and even speech, our brains are able to do those things based on a series of different patterns that we stick together automatically. By doing so, we can use and reuse groups of the same neurons for seemingly different tasks. Its essentially built-in data compression, for lack of a better term.
If we were to ignore real constraints like the time it would take to map out all of the connections in our brain, we would naturally start to store patterns of neuron connections, patterns of how those neuron clumps interact and other key features of operation.
My reasoning is that we would start to get extraordinary “compression rates” for this data. If we memorized a complex pattern of 100 neurons, we could likely reuse that “data” a million times over for other major components of the brain.
By the very nature of how we store information, data loss will happen and it’s unavoidable. We would need a new form of brain that was capable of storing blocks of data 1:1.
Also, your question is also a paradox. if we were to say we a brain would need to be double the size to store itself, then you would need a brain four times the size to store both of those brains. A brain storing itself is still a single brain so this turns into a recursion nightmare fairly quick.
If we doubled the size of our brains, we could probably do some amazing things and our memories might become phenomenal. However, the way we learn and store information is basically the same and probably still wouldn’t allow us to exactly store a million prime numbers in order.
The summary of all of this is that you aren’t accounting for memory patterns and natural data loss and there are very simple reasons that a brain doesn’t “fill up”.
Edit: Psychedelics are not inherently dangerous. Neither is THC or many other compounds. Mixing drugs and/or improper dosages is what is actually dangerous. There are probably more legal drugs that are riskier than illegal ones, actually. I would consider alcohol to be a substance that carries more risks, mainly because it is legal almost everywhere.