How Are Memories Stored In Our Brains?

Physically, that is.

For example, I have a distinct memory of my first day of high school, 20-odd years ago. I don’t think about it all the time, but every once in awhile it will come back to me – sometiimes when I’m thinking about something else, and other times (like now) when I’m specifically trying to recall it.

What is going on in my head? I know it has to do with neurons, but after that I’ve got nothing. Is there a specific pattern of neurons, or pattern of electrical activity, or chemical activity, that my brain can interpret as that memory? Does this pattern remain intact even when I’m not thinking about it? If not, how am I able to recall the memory again? Given that our brains have a finite number of neurons, I’m guessing there is a limit to how many memories we can hold. Do we know what that limit is? Is it within a human lifespan? Will I remember typing this 20-odd years from now?


memory is one thing we don’t exactly understand. It appears that neurons somehow form connections which enable them to fire in sequence when triggered in a certain way. Thus, human memory is associative and memories which trip related paths can entangle. You might also mix memories together. Exactly how the brain does this is not clear AFAIK, and what’s more, everybody’s brain is slightly different in form. And humans do have an absolute staggering ability to memorize information if they work at it.

Much knowledge can remain in your brain seemingly indefinitely, but what your emember and for how long is never certain from the outset. I can still remember seemingly inconsequential details from decades ago in some thing, just because they were important to me at the time.

A recent report: For the First Time, Scientists Photograph Memories Being Formed

I went to graduate school at an Ivy League university in behavioral neuroscience and I agree that the question just isn’t answerable with the current state of the art technology. The knowledge grows by the day but the complexity of any brain cannot be underestimated. Top researchers are still studying sea slugs to figure them out while other mammals, let alone humans themselves, are much more complex. There are partial answers to your question but they would require tons of in-depth study and still wouldn’t be conclusive. I went into the field because I thought I could learn about questions like yours and it simply wasn’t there even among the top academics.

I’ve always been interested in how you can “conjure up” a complex audio or visual experience, like remembering what a song sounds like and actually “hearing” it in your mind. I can think of a song I haven’t heard in 15 years and play it back mentally. But I can’t, for instance, think back to the day I got my driver’s license and “play back” all the events of that day. That would seem to involve much less data than a song, but I can’t do it. I’m inclined to believe that what’s going on is not that you are dumping data from some databank in your brain, but rather generating the feeling that you have when you actually hear the song. If that makes any sense.

There’s also the theory that what you are doing is reconstructing the memory from a more simplified form. Music is more . . . formal for lack of a better word. It doesn’t have the kind of miscellaneous detail that the memory of a visit to the DMV does.

And we don’t actually hear music with great objectivity to begin with; you can distort musical tones in ways that are obvious on an oscilloscope, but a human listener won’t notice because his brain changes the perceived sound to what it’s “supposed” to be. So all you’d probably need would be some simplified stored ideal of the song, and your brain would reconstruct it much the same way it constructs music you hear live.

Also, you probably heard the song many, many times before you got to the point where you could remember it completely, whereas each trip to the DMV involves a zillion unique details, right?

And each time it comes back to you, you are reinforcing the storage of that memory so it does not get discarded. But you are not remembering the initial event per se; you are remembering the last time you remembered it, which in turn remembered the time before, and so on. You are not playing the original tape over and over, but each time you tape anew the output of the previous tape. This copy-of-a-copy-of-a-copy process is why details of what did happen sometimes get lost, and details that never actually happened sometimes get incorporated into that memory.

As clear as you think your recollection of any event is, it is coloured and almost certainly altered by subsequent recollections and the circumstances in which they occurred, sometimes fundamentally.

Why do you make this statement about it copying the memory? Everything I know (which is not based on professional expertise, merely hobbyist level interest), is that many connections are created/strengthened (and continuously maintained with an ongoing flow of neuro-transmitters at the synapse) to create the original long term memory. I have never read anything about a new set of connections being made when you recall it that replaces the original.

There is a closely related article in this month’s (July/August) addition of Discovery magazine. I have it but it would be much better just to read it rather than have me describe it to you.

“Replacing” the original might not be the best term, but there is a process of (in computer terms) retrieving the data, reprocessing the data and rewriting the data. The rewrite can include changes that you now believe are authentic. Newsweek also had an article about this in the last couple of months.

There are some people who think it means that traditional psychotherapy methods for things like PTSD might actually make it worse - by recalling the memory many times during therapy and focusing on its negative aspects, you are definitely strengthening it, and you may be rewriting it with even more negative overtones than it had originally.