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Comment by delichon | Hacker News Reader

Fascinating that the apparatus for memory between generations may also be used for memory within a generation. "Breaking" and "fixing" DNA could also be taken as a description of meiosis or mitosis. Perhaps there is some code re-use there.

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Antihistamines that cross the blood brain barrier make people feel stoned or tired because histamine does something entirely different in the brain from what it does in the rest of the body.

Seems like there's a lot of code reuse in the brain. It operates almost like a different sort of biology encapsulated within an animal body.

Neuron's DNA is not passed down, it would be quite logical for evolution to use neuronal DNA for weight storage.

Many nervous system behaviours do appear to be passed through genetics - for example, the ability to breathe, the reflex to avoid pain, etc.

I suspect in the future we might find mechanisms beyond simple natural selection that allowed those mechanisms to get encoded in genetics.

I think you're talking to the wrong point. These memories aren't being encoded in germ cells, they are after the fact changes to DNA in mature neurons which have completely differentiated. I would think it's very possible at that stage of development for them to add or remove segments of DNA in order to encode new information not related to the development of the cell as long as it didn't interfere too much with parts that are actively used for the ongoing upkeep of cell activity. It would need to alter how the cell functions a little bit for the changes to modify the neuron's ability to process signals though.

I should note that studies have demonstrated that bacteria who have been modified not to be able to consume lactose will develop mutations that allow them to consume lactose again much more quickly than would be expected given the number of bacteria, the rate of random mutations and the size of the genome. It has been hypothesized that there is a cellular mechanism to control which portions of DNA are easily mutable, possibly through a combination of chromatin structure, epigenetic modification and changes to the local chemical environment via metabolism.

This mechanism might exist in a scaled up form in humans.

Isn't that what happens in antibody germinal centers?

https://en.wikipedia.org/wiki/Somatic_hypermutation

bacterial plasmids are a common form of horizontal gene flow between individuals

Could they be transferred while in the womb?

I wonder if that means that each neuron could act as a mini turning machine

stop wondering and look deeper, youve bumped into the begining of an incredible journey. even individual protiens, exhibit rule paring.

My equivocation was to avoid downvote brigades that hit me last time I posited this same idea on HN.

Check out Michael Levin's work, who's done some experiments with skin cell and has shown that they learn to do stuff.

>> it would be quite logical for evolution to use neuronal DNA for weight storage.

To pass that down you'd have to replicate the connectivity of the network for the weights to be relevant right?

Related: The article doesn't say which DNA areas are broken and repaired. Nor does it say if they are modified. It seems like encoding weights in DNA would make them more robust but harder to change. If so, there should be a particular region where this is happening. Maybe there's a mapping between certain DNA areas and each synapse. That'd be really interesting.

Neurons are not on the germ line, whatever happens to their DNA is not passed down to your children.

There was another article in the recent years about neurons using RNA or DNA for storing information related to their activation patterns.

epigenetic inheritance is real

The baby is connected to the mother's placenta for months, maybe information could be transmitted then. I've never heard anything to support that idea, though!

In addition, most parts of the first cell of what will become a baby, come from the mother. This includes all DNA in mitochondria and another organelle that I don't remember the name.

Wellcome. Sometimes it may happen that familiar stem cells cross maternal-fetal barrier in placenta, persist somehow and start to function regardless, where stem cells are needed - usually in younger sibling coming from the older, in place of original cells, even in the brain - forming part of it as of another person (more or less) - interconnected but not the same..

The Most Mysterious Cells in Our Bodies Don't Belong to Us https://www.theatlantic.com/science/archive/2024/01/fetal-ma... ( https://news.ycombinator.com/item?id=38861497 )

This always seemed like one of those little biological details, like the well known example of that nerve which loops all the way down a giraffe's neck and back again in order to connect two regions only a few inches apart, that shows that nature doesn't refactor.

Because it seems like such a waste of the opportunity afforded by extended physical secueity and direct connection between mother and developing child, that some means of transferring a portion of the mother's learned knowledge, or at least some coarse grained abstraction of it, to the fetus, has never developed.

The lazy dismissal of this question is just to say, if nature needed it, it would have evolved it, but this doesn't seem to hold in every case [0]. It seems rather that there was no way for such a capability to be built out of extending existing mechanisms, with the major barrier being the absence of nerve tissue in the umbilical cord, where higher level CNS connectivity might have evolved from as a foothold

[0] and certainly doesn't account for what may happen in the future unless nature is completely done developing everything that could be developed. Nor does it incorporate the idea that human manipulation of our own biology is not itself also part of nature.

Independent of this breaking/fixing, it's already known that DNA near the synapse (not necessarily in the neurons Soma) is modified via epigenetics to sustain the synapse at the new level.

So yes, DNA epigenetic changes near the synapse are a key part of maintaining the "weight" or strength of that particular connection. ("key part" phrase because there is a lot of complexity and they haven't nailed it all down, there could be other "key parts").

>> DNA epigenetic changes near the synapse are a key part of maintaining the "weight" or strength of that particular connection.

What do you mean by "near the synapse"? Is there DNA outside the nucleus or something? Is there DNA that maps (corresponds to) the synaptic pattern of the neuron?

Yes there is DNA outside the nucleus. The DNA near each synapse gets modified (epigenetic) based on activity in that physical area so it can produce the proper proteins to preserve the state of that synapse over the long term.

Edit: the DNA is in Synaptic Vesicles

so, my body is refactoring all the time? Cool 8)

so, my body is refactoring all the time?

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