How are memories saved in the brain?
In: Biology
The truth is we don’t really know. The leading theory at the moment is that memories are the product of well-traversed neural pathways, but to explain more will require a bit of background.
In your brain are neurons, and a whole bunch of them at that. Neurons hold data, often specialized (one neuron may hold the smell of grass, for example, while another might hold an image of Kentucky blue), and communicate with other neurons via electrochemical signals. When you make a memory, linkages between neurons are created or strengthened, thus forming a memory pipeline. When you recall a memory, you take a trip down memory lane, so to speak, by reinitializing that pipeline. Memories, therefore, are collections of tiny events integrating into a whole – kind of like an impressionist painting. There are trillions of neuron connections, each representing some form of ‘memory.’ These can range from your ability to play guitar, for example, to your memory of your last birthday party.
In that way, memories are recreated anew every time you remember. Forgetting operates in much the same way – unused pathways are cleaned up and memories become weaker until forgotten (some people, such as savants, lack these mechanisms to a greater degree). Because of this re-creation, memories are subject to tampering or alteration (see the famous Loftus studies).
I hope that answers your question, sorry if I went off on a tangent 🙂
Long-term memories are stored in the configuration of neurons in your brain.
People tend to think of memories as something like a word document: that you decide to remember, find the right folder, open the document, and read the text exactly as it was the day it was saved.
In reality, no memory is truly preserved like that. What we call memories are actually closer to a live-action retelling of an event. Your neurons activate a series of sensory feelings (touch, sight, emotions, etc) that simulate what you were feeling at the moment the memory was made. This has some…tricky implications
1. Unreliable narrator: your neural network is constantly adjusting itself. Neuron connections are strengthened/weakened/emphasized/removed constantly. So even if your brain “perfectly” captured an event into a memory, over time the neurons that are a part of that memory “circuit” will change in some way. This results is features of the memory being distorted. The degree to which this distortion occurs is based on how significant the changes to the neural pathways are.
2. Lazy narrator: As if #1 wasn’t already bad enough, recent research is starting to show that when people try to remember something, they aren’t accessing the original memory: they may be accessing the most recent recall of the memory. To put this into other terms…imagine if you wrote 100 letters in a word document and saved it. Your computer is a little wonky, and you know that when you open that file again, 10% of the words will be wrong somehow. BUT the next time you open that file, you’re not opening the original document…you’re opening the 10%-wrong file, so the document becomes even MORE incorrect. Each successive time you open it, more and more words are messed up.
The above also excludes the idea that you don’t necessarily remember the objectively important details, but rather what was emotionally important to you. So there’s already bias even before you consider the wiggley-wobbly accuracy of biological memory. It’s unsurprising that eye-witness testimony is considered one of the weakest forms of evidence haha.
I’m not as familiar with the differences in short-term memory so I won’t make any comments on those.
Usually memories are stored in what’s known as your “memory area” – which is the area around between the upper left ear, and the prefrontal cortex. When you access the memory, the brain opens up a memory bank, similar to the search bar in google. Whereupon the brain needs to access the memory for survival, it just has to search the memory depending on which situation it’s in, whether its language, math, or geography. The brain doesn’t actually store anything per se, it just knows how to google things when it needs to.
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