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To add to that, there's evidence that may mean that memories are stored in DNA, shuffled between neurons in RNA capsids, evolutionary borrowed from retroviruses

To add to that, there's evidence that may mean that memories are stored in DNA, shuffled between neurons in RNA capsids, evolutionary borrowed from retroviruses. That would make each neuron a complicated computer, functionally equivalent to one pc in capability and data storage. "The neuronal gene Arc is essential for long-lasting information storage in the mammalian brain, mediates various forms of synaptic plasticity, and has been implicated in neurodevelopmental disorders. However, little is known about Arc’s molecular function and evolutionary origins. Here, we show that Arc self-assembles into virus-like capsids that encapsulate RNA. Endogenous Arc protein is released from neurons in extracellular vesicles that mediate the transfer of Arc mRNA into new target cells, where it can undergo activity-dependent translation. Purified Arc capsids are endocytosed and are able to transfer Arc mRNA into the cytoplasm of neurons. These results show that Arc exhibits similar molecular properties to retroviral Gag proteins. Evolutionary analysis indicates that Arc is derived from a vertebrate lineage of Ty3/gypsy retrotransposons, which are also ancestors to retroviruses. These findings suggest that Gag retroelements have been repurposed during evolution to mediate intercellular communication in the nervous system." https://www.cell.com/cell/fulltext/S0092-8674(17)31504-0 https://www.cell.com/cell/fulltext/S0092-8674(17)31504-0

twic 5y ago
The passage you quote very much does not amount to "memories are stored in DNA", and as far as i know, memories are not stored in DNA sequence, and would be very surprised if they were. What this mechanism does is take the transcription level of a gene in one cell, and induce a proportional signal in another cell. There are numerous mechanisms which do that in cells. Most of them are nowhere near as weird as Arc, but the net result is similar.
- caddemon 5y ago
  It's arguable that some memories are stored via epigenetic modifications to DNA, depending on how you define "storing memories". It is very unlikely it is storing memories in the way humans typically think of memories. But I don't think "in DNA" necessarily implies "in DNA sequence".
  - lolthishuman 5y ago
    For whatever it’s worth, similar conclusions are shared in ayahuasca rituals. The source of many journeys are reconnecting with the memory within DNA. I’ve had similar intuitions and heard this from more than one source that has partaked.
  - vikramkr 5y ago
    In dna definitely implies in dna sequence. Especially with dna storage becoming a thing, and with aspects of our physiology actually using dna modifications for their function and to "remember" things (e.g. VDJ recombination), its best not to confuse epigenetic vs genetic information storage. Each hypothesis implies different things and different followup questions.
    - caddemon 5y ago
      They are certainly different things, but that's why I think more specific language should be used when the difference matters. The other comment was trying to make a more abstract point about what sort of memories an individual neuron can store using DNA, the main point wouldn't really be changed if that was through purely epigenetic mechanisms. I don't think the actual argument he made was compelling, but the claim to be discussed intended a broader definition of "in DNA" IMO. It was focused on the computational implications of the amount of storage a single neuron has.
      - vikramkr 5y ago
        Perhaps, but I'd argue the differences do matter quite a bit to the computational implications, especially as it relates to ability to reprogram, state space, and persistence, and I think there would be a much different reaction if I made a post mixing up data on a computer's hard drive with the state of whether each transistor in a cpu is on or off, or something like that.
        caddemon 5y ago
        There are different types of epigenetic mechanisms anyway which have different levels of persistence/reprogrammability, so to dive into technical details one would need to get very specific. Different methods for changing the DNA sequence would also have functional differences in how they could store a memory. And it's important to distinguish these mechanisms on a single cell level versus how they function in the body as a whole. In a single cell I wouldn't call VDJ recombination memory, it's just an efficient way of encoding many different possibilities for types of receptors (and then selecting one). There exist many cells in your body that match a potential antigen you've never seen before - it's just that there are an extremely small number of them. The memory is really encoded by increasing the population of that cell in the body. Which has different storage properties than the individual cell's DNA does. Epigenetic change to a single neuron is unlikely to have a functional effect either, but it is a change that can occur to a mature cell as a reaction to the environment, in a way that VDJ recombination is not. AFAIK there is a lot left to be understood about how epigenetic modifications affect the brain. I agree this is all interesting and can have implications for computational models, but there are models at many levels of abstraction. So I don't think it is necessary to get at the biological details in order to discuss higher level computational implications. Questions about the capabilities of the memory for each individual neuron would arise, but they could be theorized about without much knowledge of biological details. Of course it depends what your goals are whether you would consider that useful. Anyway, I think we're both in agreement the OG comment was wrong, I just feel that "in DNA" is very ambiguous, and also not really the problem with his comment given the purpose of HN.
edgyquant 5y ago
I don't know about memories stored in DNA, but >That would make each neuron a complicated computer Is this not an accepted fact? Each neuron is like a tiny processor in a larger distributed like system. This is why it's impossible to build bioaccurate NNs because each neuron has ~10K connections to various other neurons.

twic 5y ago

The passage you quote very much does not amount to "memories are stored in DNA", and as far as i know, memories are not stored in DNA sequence, and would be very surprised if they were. What this mechanism does is take the transcription level of a gene in one cell, and induce a proportional signal in another cell. There are numerous mechanisms which do that in cells. Most of them are nowhere near as weird as Arc, but the net result is similar.

caddemon 5y ago
It's arguable that some memories are stored via epigenetic modifications to DNA, depending on how you define "storing memories". It is very unlikely it is storing memories in the way humans typically think of memories. But I don't think "in DNA" necessarily implies "in DNA sequence".
- lolthishuman 5y ago
  For whatever it’s worth, similar conclusions are shared in ayahuasca rituals. The source of many journeys are reconnecting with the memory within DNA. I’ve had similar intuitions and heard this from more than one source that has partaked.
- vikramkr 5y ago
  In dna definitely implies in dna sequence. Especially with dna storage becoming a thing, and with aspects of our physiology actually using dna modifications for their function and to "remember" things (e.g. VDJ recombination), its best not to confuse epigenetic vs genetic information storage. Each hypothesis implies different things and different followup questions.
  - caddemon 5y ago
    They are certainly different things, but that's why I think more specific language should be used when the difference matters. The other comment was trying to make a more abstract point about what sort of memories an individual neuron can store using DNA, the main point wouldn't really be changed if that was through purely epigenetic mechanisms. I don't think the actual argument he made was compelling, but the claim to be discussed intended a broader definition of "in DNA" IMO. It was focused on the computational implications of the amount of storage a single neuron has.
    - vikramkr 5y ago
      Perhaps, but I'd argue the differences do matter quite a bit to the computational implications, especially as it relates to ability to reprogram, state space, and persistence, and I think there would be a much different reaction if I made a post mixing up data on a computer's hard drive with the state of whether each transistor in a cpu is on or off, or something like that.
      - caddemon 5y ago
        There are different types of epigenetic mechanisms anyway which have different levels of persistence/reprogrammability, so to dive into technical details one would need to get very specific. Different methods for changing the DNA sequence would also have functional differences in how they could store a memory. And it's important to distinguish these mechanisms on a single cell level versus how they function in the body as a whole. In a single cell I wouldn't call VDJ recombination memory, it's just an efficient way of encoding many different possibilities for types of receptors (and then selecting one). There exist many cells in your body that match a potential antigen you've never seen before - it's just that there are an extremely small number of them. The memory is really encoded by increasing the population of that cell in the body. Which has different storage properties than the individual cell's DNA does. Epigenetic change to a single neuron is unlikely to have a functional effect either, but it is a change that can occur to a mature cell as a reaction to the environment, in a way that VDJ recombination is not. AFAIK there is a lot left to be understood about how epigenetic modifications affect the brain. I agree this is all interesting and can have implications for computational models, but there are models at many levels of abstraction. So I don't think it is necessary to get at the biological details in order to discuss higher level computational implications. Questions about the capabilities of the memory for each individual neuron would arise, but they could be theorized about without much knowledge of biological details. Of course it depends what your goals are whether you would consider that useful. Anyway, I think we're both in agreement the OG comment was wrong, I just feel that "in DNA" is very ambiguous, and also not really the problem with his comment given the purpose of HN.

edgyquant 5y ago

I don't know about memories stored in DNA, but >That would make each neuron a complicated computer Is this not an accepted fact? Each neuron is like a tiny processor in a larger distributed like system. This is why it's impossible to build bioaccurate NNs because each neuron has ~10K connections to various other neurons.