system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can we create, see, hear mental images and sounds in our minds?

How does that work?
gpt
To be clear, there are big parts of this we don't understand, and to make it more complicated, some people don't create mental images.

But for those of us who do it's all about how memory is formed. Memory isn't stored like in a computer. When ever you experience things certain neurons in your brain sends signals to other neurons your brain. Memories form a bit like tracks form in a forest. When many people take the same path you'll start to see a track form because the vegetation is trampled. When two neurons send a lot of signals to each other, their connection is strengthened. And neurons with strong connections send messages to each other more often, just like a well trodden path in a wood is more easy to follow.

When you are remembering something, your brain is simply walking down these familiar paths, i.e. the same neurons that are communicating when you are experiencing something are the neurons that communicate when you remember that thing. So when you remember something you've seen, it actually involves using the same neurons that were involved in actually seeing that thing.

The same thing happens when you imagine something because every memory doesn't have a unique group of neurons, but rather certain patterns associated with certain concepts, images, sounds etc. Every time you have a memory where a football features, some of the same neurons will be involved in all those memories, and those neurons will also activate when you imagine a football without it being in a memory.