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So a hypothetical concept I’ve been playing with lately involves the “RNA memory transfer/storage” hypothesis, recently notably demonstrated in slugs a few years back which made a few headlines. The basic idea I’ve taken from it is the idea of memories being connected to or “encoded” with epigenetic changes from RNA, with “memory” transfers of a sort possible via engineered epigenetic changes that in turn alter the brain’s connections/function.

So let’s say a certain memory or pattern of memories (with memory here more meaning instinct—some sort of stimulus-response pattern, or unconscious course of action) was installed into an organism by “encoding” it via engineered epigenetic changes to genes, with the related synaptic formation happening as a result of the genetic effect/“information”.

In order to make this effect work, aka targeting the right neurons in order to form a new and particular pathway in the brain—and NOT overloading things with a bunch of neurons all trying to form many pathways—does this process need to be limited to a specific set individual neurons (the “points” making up a given memory’s pathway)? Or can the epigenetic-change-enacting material be more broadly spread around (to all neurons of the general type(s) involved in the desired behavior/memory, or even just to all neurons?) with the formation of synaptic pathways based on the changes then sorting itself out naturally, and not being overloaded from every cell all getting the same “form this connection” instruction? The last thing I want to do there is prompt so much signaling and receiving in every brain cell that I just give the host a seizure or something.

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    $\begingroup$ Epigenetics have nothing to do with neurons or memories. It is just one of the mechanisms for regulating gene expression. $\endgroup$
    – Negdo
    Jul 7, 2023 at 9:06

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  1. Unlike us mammals, who rely most on learning, some kinds of animals, most notably birds and insects, rely very strongly on very elaborate and complex built-in instincts.

  2. At the initial point in the life of the bird or insect it was one single cell.

  3. Whatever programming was present in that initial single cell is still present in all the cells of the body.

  4. But it is expressed only where needed; which means that the programming includes a regulatory mechanism.

  5. Answering the question, the programming must include both the instincts to be induced and the regulatory mechanism which controls their expression in the neural paths.

P.S. Instincts are not memories. They are not similar to memories. It is very unlikely that they are encoded in a similar way as memories. On the other hand, we have no idea* how memories and instincts are encoded, so that it is possible, as unlikely as it may be, that they are encoded in a similar way.

(*) Better said, we have lots of ideas. Unfortunately, they are just that, ideas, with no real experimental support.

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  • $\begingroup$ Maybe “instincts” carries too specific a connotation to use there; when I say “memory” and “instinct” I’m using them both in a way similar to the linked paper’s experiment, where it refers to a response to a particular stimulus (in that case called a “memory” because it was trained into one group of slugs to react a certain way, then transferred to a group that never experienced that training) $\endgroup$
    – inkwell87
    Jun 29, 2023 at 19:27
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    $\begingroup$ @inkwell87: What was actually transmitted in the experiment was neither a memory nor an instinct, but only a conditioned reflex. Instincts are much more complex than that; but the importance of the experiment is that it hints at a possible basis for the transmission of instincts. As they always say, more research is needed. $\endgroup$
    – AlexP
    Jun 29, 2023 at 19:40
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    $\begingroup$ I read a while back that, if you raise mice in the presence of cats, then the children will have an automatic fear response to cats that you don't see from children of mice not raised around cats... so it seem that epigenetic memory can actually be relatively complex. $\endgroup$
    – Nosajimiki
    Jun 29, 2023 at 19:49
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    $\begingroup$ @inkwell87: The best bet at the current level of knowledge (where current means some 30 years ago when I was young and reading such things) is that the regulatory mechanism affects development and does not work on adult animals; this is why evo-devo is such a big thing. But if you figure that out there are multiple Nobel prizes in biology to be awarded. $\endgroup$
    – AlexP
    Jun 29, 2023 at 21:37
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    $\begingroup$ @AlexP Exactly, and that is the difference between an instinctive fear and an epigenetic fear. Both are complex, automatic, genetic responses to a stimulus, but one kind only expresses based the experiences of your parent. $\endgroup$
    – Nosajimiki
    Jun 29, 2023 at 21:57
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Going to go off the range here, admit my ignorance, and attempt to make sense of this answer that my Neurologist tried to explain to me. (Yep. I discussed this with him, for reasons.)

Basically, there seem to be a couple (or more) of "classes" of auto-generated instincts; think of them as the "firmware" that operate the biology of the creature being studied. Humans actually have more, but during their development they become sub-classed in

  • "pre-disposition", such as handed-ness (right-handed, left-handed, or ambidextrous),
  • "autonomous-seeming reflexes" (squeamishness, attraction to or repulsion from various environmental attributes such as dirt, dust, muck, water, etc.) that can be "paved over" with new(er) conditioning, and
  • "permanent response" like pain, hunger, panic, etc. These are almost impossible to re-train, so they are considered, well, permanent because they appear to promote the survival of the being.

This is vastly over-simplified, but I think you can follow what I'm saying. What he pointed out is that we're not really sure how this "pre-programming" takes place: if it occurs, it expresses itself in the next generation of the creature (or person). A favorite example of this is musicianship, which is said to be perfected (or be close to it) every three generations. It has to do with the level of commitment of the person (or people) expressing that skill, act, or behavior and whether or not it is present (or expressed) by the male partner, female partner, or both at the time of conception. Being an Engineer of various sorts (Computer, Electrical) I think I understand what he was trying to say.

The "RNA Transfer" - at least according to my Neurologist - seems more like you want to inject perhaps a skill or ability like a drug. His take on it would be like, "Oh, you want to be Right-Handed? Well, here..." and the specialist, hack, or general practitioner simply injects you with a substance (description can be anything) then tells you that your new capacity will develop in the next week or so, "...so don't fight it. If you feel the need to pick things up with your right hand, so much the better..." He was intrigued with the idea because it would enable someone to change whether they were foolhardy, or alter their stress level (likeliness to panic, coolness under fire), or perhaps cure a person's fear of loud noises.

His final attempt at explanation was that it would be like allowing a character to rearrange their attribute scores, advantages and disadvantages (like in the Hero Game System, or perhaps the GURPS System - and countless others) long after the character has been generated, during the campaign's continued progress. He also mentioned that it's not out of the realm of reality - we just don't know yet.

So - finally - in answer to your question - it appears that there might be some traction there but it would edit the underlying fundamentals of a person's general makeup. We're not too sure if you couldn't also expand an individual's capacity to learn (raise their IQ maybe?) through this same method. You are, after all, re-writing some of the most important building blocks of the individual. Maybe enhance their body's capacity to process neural signals (maybe through expanded nerve pathways?) increasing and individual's basic speed (running, or drawing a firearm from a holster) or increase their sensitivity to touch (like sensing textures, reading braille in microfine points).

According to my neurologist, this would be like the basics for creating mutants (like the X-Men) because depending on the details those changes could naturally express in the next generation: the subject's children. And if both partners had been thusly modified, the end result could be anything from a preternaturally fast human with mesomorphic skeletal construction and unbelievably fast healing or a hopelessly myopic person with reduced hearing and hemophilia --- or some other unexpected foundational shift, for good or ill. As Batty Coda said in Ferngully: "It's Darwin's grab-bag!"

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"by “encoding”" ... it's called pain. "'memory'... meaning instinct", then yes.

In a single generation, the offspring of mice trained to associate the smell of almonds with electric shock will be born with more receptors in their noses (or brain synapses?) to specifically detect almonds. NOVA S50E10, Your Brain: Who's In Control?

The episode also mentions descendants of those who faced famine in WWII having metabolic problems. Not only are you a product of your environment, you're a product of your parent's environment, genetics notwithstanding.

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