The issue is complex because we don't really fully understand how memories are formed, stored and accessed. We have some idea of the process, but a lot of it is speculative. The current belief is that memories are stored in the connections between neurons. During the day memories are formed in the 'daily short term' part of the brain, and then in the night while you sleep your brain sorts through stuff accumulated during the day and decides what to keep and what to neglect (memory consolidation). When a memory is stored, the triggers that recall the memory are also set, strengthened and weakened, so it is possible to have a clear memory but have issues retrieving it, and those can actually work in interesting ways.

During the day connections tend to be strengthened but not often weakened, but during the night the brain enters a low-energy mode where it also weakens connections across the brain. Simultaneously it processes and refines memories acquired during the day.

There are tricks to forcing the brain to not wipe memories acquired during the day. One example is 'active recall'. Basically say you're in a class and learn about the product rule and quotient rule in calculus. That night, get a blank sheet of paper and write down everything you learned about the product and quotient rule, with zero notes or references. This act of deliberate retrieval (a bit of struggle is good! Fight for it!), followed by a brief review will tend to encode that information/memory as important and not tagged for wiping.

There are memories that aren't episodic either. Procedural memory for example is consolidated greatly during REM sleep, which is how you for example get better at playing the guitar. If you don't get any REM sleep, that consolidation process is disrupted and you're slow to actually acquire those automatic skills. Declarative or episodic memory however is consolidated more during slow-wave sleep.

I find out of all the areas of scientific research, the research on memory and skill formation, retention and access to be among the most interesting.

Neuropsychology student here. The more you learn about memory, the harder the answer to this question gets. Do we have a good idea of how memory works and how information is stored? Short answer, not really. We know that the brain has a limited storage capability, and we also know that your neural pathways can be “pruned”, aka cut down via the removal of certain neurons. If your brain deems a certain piece of information unimportant or finds it consumes too much energy, it will get rid of it, often through a process known as long term depression (LTD).

Additionally, you need to consider the aspect of memory retrieval. Forgetting something isn’t necessarily the complete loss of that information in your memory storage: sometimes, the environmental or physical circumstances mess with your ability to recall information. This is why you sometimes forget something, but then are able to remember it at a later moment. This is a fascinating aspect of psychology which ties into topics of cognition, attention, and so on.

Think of it like the internet. But with no IPv4 addresses, no DNS and no search engines. The only way that you can navigate to the page that you want is to find a page that links to it. You've got your frequently used pages bookmarked so you can easily jump to them but from there you've got to figure out a series of links to the page that you want. Now when you dream your brain looks at what you've done for the day and goes and makes new links. So the more frequently you access a particular page the more pathways there will be to get to that page.

The vast majority of your memories are unavailable to you simply because there's no link.

When we forget, the physical wiring of the brain changes back — the connections that once held the memory become weaker, fewer, or reorganized. It’s not like deleting a file, it’s more like the trail through the forest grows over because nobody walks it anymore.

So, if you are exposed to more saturated media environment would the brain have to compete with the energy or noise of adding all kinds of new weak connections, potentially taking away from the establishment or maintenance if of existing or more important connections?

could this help in researching things like alzheimers and dementia?

My brain made a memory of a brain making a memory and I made a memory of me posting about my brain making a memory of another brain making a memory.

Fun fact:

if you watch this then most likely what you're seeing is what's currently happening in your brain too by making a memory if this video

Thanks to cameraman John for shrinking down a thousand times and capturing this moment for us!

Inside Out told us before

That's akin to saying 'No on really knows how the universe works'. We do know a lot about how different forms of human and animal memory work, but as in all science we do not know everything, and when questions are answered, new questions often arise.

Are there maybe certain forms of memory that piques your interest?

The Computational Brain by Sejnowski & Churchland gives a more detailed peek at what it means for groups of neurons to encode a memory

I would recommend “In search of memory” by Eric Kandel as an initial read.

There’s a lot of research being done in this area. Most of them appear to be taking the psychology/ cognitive neuroscience path.

My university (Sussex) has done extensive research on the molecular mechanisms of memory formation. Here is a seminal paper from 2005, although much more information now exists.

https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1460-9568.2005.03970.x

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Where’s the campus full of hippos?

Which one? Not descriptive enough.

Looks like a flea circus

I have so many. It’s crazy sometimes to think back on your life and feel like you’re somewhere else but you’re so far away from it. Sometimes now, I think of my cherished memories and feel like I didn’t get to be in those moments long enough, like I didn’t know at the time that my life was my life or that it mattered to me - the people the experiences whatever. Sometimes now I wonder what even is the point. Each moment is just that one moment, but when it becomes a memory we carry it into the next moment and our entire life is always only the present. It just weirds me out.

I’d love to go back and sit on my grandmas bed one more time and watch a movie, or spend time playing and using my imagination like I could when I was small. Memory is all we get in the end, and even that isn’t always guaranteed. Assuming nothing happens, there’s a long way to go still from those memories and more to be made.

Outside of that tho, I’ve memorized so much pointless information as well haha

I can tell my memories change as I remember them.

I can tell when I fill in holes. As more and more holes in core memories form, the less the memories feel like a memory and more like a fantasy.

I also noticed that memories have metadata attached to them. A confidence level if you will. I’m hyper aware of how confident I am in my memories.

It becomes a memory of a memory of a memory... like photocopying something over and over again.

That explains why stories get better with each retelling.

https://www.change.org/Revive_the_lost_past Potete firmare la mia petizione?

I think my memories are stored in a big magicians hat somewhere in the neocortex and all my memories and thoughts are in the hat in the forms of folded strips of paper and every so often a big glove reaches in and grabs one at random and then reads it out loud in a British narrator accent

The truth is that we aren’t fully positive on how and where memories are stored, but there is a strong theory that I support.

Imagine you walk into a library. You want to find a specific book, so you go and look on the computer and you find the location of where that book is. Now instead of having one location for the book, each page is stored in a different place, but you have the locations of every page. So you go and hunt down each page, and now you have the full book! To add another layer to this, imagine you just have a pretty solid idea of which pages are in this book and in what order they go in. Each time you find the pages and make the book, you have to later take the book apart and put the pages back. Do this enough, and things can get a bit messed up, and the book isn’t really the same as it was the first time.

Source: I am a neuroscientist

Exactly. You need a lookup table.

So once the brain gets the inputs it has to go fetch the memory.

Ignoring what is driving the need to get the memory, the brain part that is responsible for fetching the memory from.... er... Itself probably does what this guy talked about.

However that lookup table to know that such a memory exists must be there, another table or field to confirm that pages of this memory should be searched for here instead of randomly scanning the entire brain everytime.

All these lookup tables have to be itself stored somewhere. In cells or the brain? Again as what OP described as connections between cells?the synapses?

So puzzling.

I feel the brains understanding of the brain is limited by that very limitation of the brain

Meaning we will never understand a limitation of the brain due to thaf very limitation in the brain. The only way would be to evolve beyond today to overcome it.

These kinds of estimations make assumptions about what memories are. There's decent evidence that each cell can hold massive amounts of data on the quantum level and may be essential to what memory and consciousness are. Long-term memory seems to be inhibited by blocking protein synthesis which reduces the strengthening of neural connections, but anesthetics also interfere with memory, presumably through electronegativity or hyperpolarization of neurons and can interfere with transcription on the quantum level.

This itself is an assumption about how memory works, but it's possible the neuron may not be the most basic unit of memory, it could be segments of microtubules that multiple neurons encode and possibly aid in distinguishing minor differences in groups of neurons that frequently fire together. In this model, It would be something like 1,000 trillion x 15,000! which is an ungodly number, but the brain also doesn't wire in every possible configuration at once so idk how'd you'd even go about a 'reasonable' estimation under this model but it's safe to assume 'we don't know' or 'somewhere between a lot and may as well be unlimited' are equally valid answers until we know more.

They came to those numbers by quantifying neurons as if they are standard flash storage, but that's not how the brain remembers things at all. The brain has as far as we know, potentially unlimited storage space, as patterns in numerous neurons have a very very high limit of numbers. Every memory is made up of a pattern of certain neurons firing, but these neurons often overlap with other memories, which plays into why certain memories are remembered when we remember say, a texture or smell related to it. Even 6 neurons could potentially store dozens of "memories" if not hundreds, they will just be very simple memories.

Not sure, it's not really possible to have an identical brain without memories...

I don't know if the brain works like that. A memory being formed doesn't necessarily grow in mass. However... Brain diseases like Alzheimer's and dementia demonstrate how loss of brain mass and memory.

Already existing neurons are linking forming memories. That said... I wonder if the brain ever creates more brain cells to acomodate a new memory...

How and why they do it is beyond me though.

As you ride your bike down the grass hill in the same way every day, the path will first start to be obvious by the grass all laying down in the same direction after a day or two. After you keep riding down the same path on the hill, the grass will eventually carve further into the ground and make a wider path and begin the carve into the ground. Your familiar feeling with things are attributed to your memory of the things. In the same way that your bike will create a dirt path in the grass over time as you ride it again and again, the memory becomes stronger and more established the more you experience the room or event or experience.

Just as the dirt path your bike makes doesn’t occupy more space, but does hold the information of the path - your memory “paths” in your brain do not occupy more space in your brain.

I am trying to understand 'formed and reformed'. So... say I have this set of memories that are invoked by a madeline. The neuronal connections that hold/constitute those memories - are they always there in the background? Or do they unform and then reform when invoked by "madeline"? Using the iPod example, invoking "Back to Black" always retrieves and processes the exact same set of zeros and ones, in the same physical location as when originally formed (and not unformed). What's happening when I invoke "madeline" - is the madeline an index locator like the song title, or is it like sheet music which lets me reconstruct the song without actually storing the song?

I understand that long term potentiation isn't the definitve explanation, but I fail to understand why this paper makes absolutely no mention of it and repeatedly speaks about finding a neurophysiological basis for long term memory. Have they never heard about it?

Methodology:

The survey was distributed from August-October 2024 to two separate cohorts of neuroscientists: (1) those who had published research papers directly related to the neurophysiology of memory (Engram Experts); and (2) any attendees with an abstract listed in the Computational and Systems Neuroscience (COSYNE) conference booklets from 2022−2024 (COSYNE Neuroscientists). COSYNE attendees are self-described as those interested in “the exchange of empirical and theoretical approaches to problems in systems neuroscience” [26]. The questions were focused on their beliefs about the physical basis of memory, as well as the implications of these beliefs in various theoretically plausible scenarios. The survey and its implementation were reviewed by the Pearl Institutional Review Board and received an exemption determination (#2024-0303).

Survey questions The survey consisted of 28 questions divided into six sections: ‘Demographics’, ‘Structural basis of long-term memories’, ‘Theoretical implications of memory storage’, ‘Brain preservation’, ‘Whole brain emulation feasibility’, and ‘Familiarity & comfort with the topics discussed’. Most questions were mandatory for completion, except those that asked participants to optionally provide additional commentary on their responses.

Each of the main sections (i.e., all excluding ‘Demographics’ and ‘Familiarity’) were preceded by a page of information providing contextual information and definitions required for the questions that followed.

Data:

Data Availability: A list of the survey questions is available here: https://osf.io/agkrn

The full set of participant response data is available here: https://osf.io/bas2u

I wonder if this can prove something I’m curious about. I’ll admit this isn’t science but I’m wondering if a study like this can prove something for me and that is; that memories exist ONLY in the brain and this idea that a “soul” carries a complete set of the same properties as a living human is preposterous. That when the brain dies, everything that made someone “who they are” dies with it.

Technically speaking your neurons are still there, they're just not as connected anymore.

There is one upside that they are doing it on dead people - at least they won't die from cringe. After all, all people have stuff that they want to hide even if they remember it well. Ability to read memories based on patterns in the brain is dystopian and nothing good will come out of it. Because what could? Installing fake memories as if it was software? 

>Curious if Nuralink tested the AI chip on dead brains to see if they responded?

They have not, because this isn't an unexplored question. We know that tissue needs to be relatively healthy to get electrical recordings worth a damn.

Electrical activity in neurons is metabolically expensive, and neurons are delicate. You can do slice electrophysiology experiments, but those cells need constant metabolic support (in the form of external energy and oxygenation), and recording times are limited to several hours after sacrificing the animal. This isn't anything new, electrophysiology has been around since the 30s, at least. Earlier, depending on how you define it.

>And Nuralink has been active since 2016.

Neuralink is a relative newcomer to the field, and hasn't published anything of any significance yet. Companies like Blackrock have been doing human trials in patients since well before Neuralink was established.

Neuralink is certainly the most marketed company in the field, but they are far from the most accomplished or most promising.

Now I gotta ask my best friend to laser my hippocampus too?

oh man no way I'm going to remember all this