Memory is literally everywhere. There is already evidence that the brain can encode memory in dynamic molecular processes, and that interference of those process can interfere with an animal's ability to recall memory.
Your point about timescales is a good one, and provides a clue: the timescales over which a given medium of information can be encoded to or decoded from and over which it decays should provide a clue about the timescales we might expect organisms to experience it in. Mammals and other creatures with RNA experience memory over a whole continuous range of timescales. Why wouldn't RNA, which is optimized for encoding information, be just one of many mediators of memory?
Of course there's a lot of other stuff RNA can do like catalytic activity, triggering RNA interference or reacting to other molecules (riboswitches). But information storage isn't really anything RNA is known for.
Although I'd again argue that there is no single "true" medium or mechanism of memory.
I'd remind you that DNA is indeed memory. It's memory whose recall is heavily modified and contextualized by its environment, for example methylation, the topology of how it is currently twisted, the kinds of nutrients available for molecular synthesis, etc.
If RNA mediates memory on a sub-generational timescale, it seems that it'd provide a dynamic, contextual bridge between generational memory in DNA and shorter term kinds of memories that play out over timescales less than an individual's life. So that the molecular formation of a given memory would have a semantic basis in the longer term context. A concrete but way oversimplified example of this might work:
You go through a traumatic experience where you almost die. The specific way you almost die is related to a number of factors involving your ability to run fast enough. The long term memories of that experience are then encoded as proteins by a mosaic of genes related to certain muscles, their shape and size, certain metabolic pathways, etc. The way we might unpack or interpret that memory at any given time/context could be as a gutteral impulse that results in such realizations as "I need to get more exercise" or "my grandparents had heart disease, maybe I should go to the doctor" or "wow I'm sure hungry for fish", etc.
Btw I'm not even arguing that it's as clear cut or simple as that, just sharing how I intuitively make sense of all this evidence and these hypotheses.
Yes, it contains information. But you can't write to it.
Viruses integrate into the human genome, then decay and eventually become fodder for new regulatory regions and genes.
During human life, your genome is mutated, and your body repairs it, sometimes making mistakes, which are permanent (and passed down to your children if it happens to the germ line).
I could go on...
If you're saying it's theoretically possible, I would agree that it might be, and that there is a potential for DNA to be memory. But to claim that DNA is memory without a known write process is premature I think.
My hunch is that you're thinking of memory as being equivalent to RAM in a computer. So I'll remind you that read only memory is still memory.
Some microorganisms, like viruses, do directly modify DNA. That's where CRISPR came from.
I'd encourage you to check out the full range of definitions of the word "memory".
An imprint of history is not memory, in much the same way that fossils, stars, the environment is not memory. Human DNA has not been written to. It is edited in only very specific circumstances - DNA repair, TCR/BCR recombination, meiosis and interestingly, and possibly relevant - LINE-1 transposons in neural tissue.
At any rate, DNA encodes useful information related to how an organism's ancestors were able to survive their environment. If you prefer not to call it "memory" for semantic reasons, I don't really care too much, although my opinion is that memory is too deep of a concept to be narrowly confined like that. Nevertheless, even if you don't call DNA memory, it doesn't change my point in the comments above, which is that the information encoded in DNA is directly relevant to any survival related memories, and so it would make a lot of sense if such memories were formed in direct, physical reference to that information. Seeing as how it's been shown that protein formation is involved in memory formation and recall, and seeing as RNA is how proteins get their molecular structure, it's not a far reach to see the possibility that RNA is a contextual bridge for memory to be encoded in reference to survival related information provided by DNA.
None of this requires that DNA be writable in the same way that transistor based me let is writeable. DNA is written through a probabilistic, distributed process, but it still encodes information about the molecular tools its carriers successfully managed to survive and reproduce with.
So as an simplified analogy, the DNA would be like a dictionary of common words that could be used to encode a meaningful story about something the organism has experienced. The RNA would be like the handwritten copy of each word as the story is written down on a piece of paper. The paper with the handwritten story is analogous to the proteins that have been shown numerous times to be involved in long term memory storage and recall.
Well there's lots of information there which can be used to infer aspects of previous states. I assume it's more of this aspect that is being referenced, rather than what is encoded in the RNA.
I am personally interested by the 'RNA Computer' hypothesis which posits an additional layer of differentiation in computations performed by interacting RNA.
I have also read of experiments where memories (learned behaviors) were transplanted by injecting ground-up neural material. Flatworms were the subject I think.
Of course this is all near the edge of mainstream, but I think genuine science demands openness to new ideas.
Whether it's learned or you were born with it doesn't really change that the information had to be stored and transferred which is...memory?
I remember hearing about this one really interesting experiment where they would expose mice to a specific scent (I think it was citrus), and then give them a shock. Obviously after a while, when the mice smelled that scent they would get nervous and try to hide (or something along those lines, this is from memory so forgive any erroneous details). They then bred those mice and separated the offspring from the parents so that there was no way they could learn about the smell from them.
When they exposed the offspring to the smell, they reacted in the same way their parents did. Without ever having been exposed to it before, or knowing about the shocks. Pretty interesting stuff.
> I don't think there's any real doubt that memory is
> stored in neurons, this is really a fringe theory.
All theories are fringe theories at first, that's where they start (as hypothesis before there's any experimental evidence or mathematical proofs).
I would agree that there is little doubt that memory is stored in neurons. However, that does not exclude some memory being stored elsewhere. It's generally accepted that the brain stores memories first in short term memory, and then after a time some of those memories are stored in long term memory, with the memories chosen according to some criteria.
I could see RNA memory as a third stage of memory storage. Memories that the brain views as high impact to the species according to some criteria might get copied from long term memory into RNA memory to be passed on to future generations, accessible only by subconscious.
If RNA is not simply the conduit between DNA and protein, but the original biological operating system, from which many functions have been refactored out to DNA and protein it's fascinating to think about what other functions may have existed and may still exist entirely in RNA.
I like to assume that RNA is the original biological information store, the original structural material and the original catalyst. DNA is the long term cache version of RNA information, and protein the improved structural and catalytic material. The information in RNA can be translated directly to and from DNA, and there is an interesting idea that the mapping from RNA codon to amino acid may have began directly on the RNA strand, some RNA sequences seem to have an affinity for certain amino acids.
The claim as I understand it is that there is no “memory” at all. What we experience as memories are simply input parameters that signal our brain to begin a particular function. In the way a neural net does not “remember” the training data but carries out what it “learned” anyway. I have problems explaining this idea as I think it is full of holes and would require some fundamental changes in how we think about feedback structures (I mean this neurologically as well as mathematical/computational).
Either way if most people don’t doubt memory storage in neurons then they are very quite about it. I’ve rarely ever read an argument for memory storage mechanisms in the brain. A good reason for this is simply the question: Where is it then? Neurons individually can’t really provide this sort of expansive data storage. And what they seem to be able to account for is too little and too widely spaced apart. Interestingly this spacing also provides a counter argument against the complex processing that would be required if there wasn’t a memory mechanism.
Personally I think the dismissal of memory comes with a lot of hubris attached, as well as a total lack of understanding information theory. Information theory itself seems to be popularly bemoaned by neuroscientist as well. But it’s hard to see the alternative and is a bit paradoxical since the only way I can seem to understand the “no memory” claim is by using a computer neural net metaphor.
[0]Memory and the Computational Brain, C. R. Gallistel and Adam Philip King
You can read the main thesis here https://onlinelibrary.wiley.com/doi/pdf/10.1002/978144431049...
Human language is like that, full of ambiguity, of implicit baggage.
If you feel "memory" means a recording of an event, or a photo book, then faced with the discovery that brains actually don't work like that you may want to state "neurons don't store memories!".
Are you claiming there is a large subset of neurologists how do not believe in long-term potentiation and other plasticity processes driving long-term retention of memoranda? If so, could you please show me to these crowds?
Long-term potentiality is not the point of disagreement. The disagreement is that individual memories are not recalled, as they are not stored, per se. The idea is that neurons acclimate to inputs, so that when we "recall" them we are not retrieving a "memory" from a storage location but instead are being activated in a way that allows us to preform a learned action.
I imagine those marble/cardboard diagrams of logic gates, where the cardboard flap will be left in a particular position after a marble has passed. In this way you can add numbers by dropping marbles into the appropriate input slots. Yet in this way, one could not derive prior calculations, as it does not store this information anywhere.
Book: [0]Memory and the Computational Brain, C. R. Gallistel and Adam Philip King
You can read the main thesis here https://onlinelibrary.wiley.com/doi/pdf/10.1002/978144431049...
Review: https://www.researchgate.net/publication/262093114_Man_as_Ma...
Also please take all my comments with a grain of salt. I am not expert, I'm just trying to restate what I've read and understood.
Another attempt:
Straw man:
Phones are too slow and too dangerous to be used as a real time vehicular traffic indicator. If drivers were to text their location back to google every 10 seconds, they would have too many accidents. It isn't even possible to look up the location on google maps and then text a geocoordinate in 10 seconds. Drivers just wouldn't do this anyway because there is no incentive for them to do so. Google would have to pay drivers $2 or so for each location bulletin. That would cost billions and google would go bankrupt.
[1] https://www.cell.com/cell/fulltext/S0092-8674(19)30448-9 [2] https://www.cell.com/cell/fulltext/S0092-8674(19)30552-5
But it is a thing to write in GPT style.
GPTs want to be human like, for funding.
Chess AI's still can't play like a human (but people are working on it), chess AIs were designed to solve problems.
The easiest way to pretend to write 'human like' for a computer is to say as little as possible with tiny contractions and poetic words.
Some humans similarly do this, if you get paid by the word it makes sense.
OP style fails on this topic because it's so technical.
GPT-3 wasn't even designing to mess with our heads, but it does, wait till someone designs it to. It's very possible, because it's not about intelligence, making it worse is easier than making it better. If you use engagement as a measure of 'success' you can see you can evolve GPT-3 quickly to a worst nightmare. (It is already a nightmare)
My first reaction was to downvote your comment for the ad hominem, which doesn't contribute to the discussion. But I can see you are giving consideration to the article, and want to discuss it further - it's just that you haven't got enough out of it to make much of a start, and so this is your conversation starter.
I'm assuming you've labelled this a "fringe theory" by a "crackpot" not to be nasty, buy in order to start a conversation.
Let's start with your statement:
> I don't think there's any real doubt that memory is stored in neurons
The question is "how?". The article is postulating that each neuron is a computer, and RNA is a storage medium.
You say "my first objection would be that RNA would be far too slow for this purpose." That's because your thinking about RNA is limited to what you understand about RNA. You've learned about mRNA, which is one application that uses this molecular format, but it's not the only possible application.
The article suggests that the data transmission protocol which leads to thought and/or behaviour could be electrical, through simultaneous aggregated neuronal RNA based data processing.
Read the section he quotes from Ron Maimon, subtitled RNA ticker tape. What do you make of this statement?
"The RNA in a cell is the only entity which is active and carries significant bit density."
DNA certainly encodes for a significant amount of information as well. And why not proteins, there are a lot of proteins in a cell and you can also modify them in various ways. A cell has an enormous amount of state, any of it could theoretically store information like memory. There are a lot of different molecules active in a cell, in various modification states, at various locations, and all of that could encode information.
What this blog posts doesn't provide is any experimental evidence, this is a pure thought experiment. If RNA were to actually store memory, that would be great. Because determining the RNA sequences inside a cell is something we can do.
It appears that the brain cells in particular actually do develop significant changes to their DNA.
mRNA and tRNA move, so "active". Ribosome is also (re)active, and "the ribosome is itself composed of both RNA and protein, likely reflecting its own descent from an RNA world." [1]
[1]: The Ribosome Moves: RNA Mechanics and Translocation
True!
> What this blog posts doesn't provide is any experimental evidence, this is a pure thought experiment.
Yeah, so?
Why? Ad-homs aren't necessarily bad, it's contextual.
More informative to state the views you disagree with and say why.
There are other weird parts in the blog post, for example claiming that a particular protein kinase is involved in mRNA transcription. That is by definition wrong as a kinase is an enzyme that transfers a phosphate, so a protein kinase transfers phosphates to proteins. And the RNA in this hypothetical memory storage would not be mRNA, as that by definition encodes for proteins.
The person cited in the post is also a crackpot, I've quite a lot of experience with his exploits on the Stack Exchange network. And I haven't found a conspiracy theory yet that he didn't like. This is not hyperbole, I learned of a whole bunch of conspiracy theories I didn't know existed through his posts.