8 ms·

This line surprised me: “The dirty secret is that we don’t even understand the nematode C. Elegans, which only has 302 neurons [in contrast with the nearly 100

by mojoe 11y ago

This line surprised me: “The dirty secret is that we don’t even understand the nematode C. Elegans, which only has 302 neurons [in contrast with the nearly 100 billion in the human brain]. We don’t have a complete model of this tiny organism.” It's very interesting that there are creatures that have their entire behavior determined by just a few hundred neurons. Idid not know this.

IndianAstronaut 11y ago
Keep in mind that each of those neurons has over 10k genes and hundreds if not thousands are going to be expressed at any given time. Each cell is very complicated.
- TeMPOraL 11y ago
  It's incredibly sad that they don't talk more in high school about DNA methylation and genetic expression in general. Or at least they didn't when I was a high-schooler. It changes the perspective on DNA - from being "the recipe of life, your entire source code" to "list of functions that may or may not be active, depending on other functions, environment and whatever is or is not active in the parent mechanism that does the cell replication (hidden state; c.f. Reflections on Trusting Trust)".
  - IndianAstronaut 11y ago
    The analogy to a computer is a good one. A computer may have lots of software. Installed, but only some of it is used. Sometimes the software interacts with each other.
kkylin 11y ago
The whole worm is not that many more cells (a big fraction are neurons): https://en.wikipedia.org/wiki/Caenorhabditis_elegans https://en.wikipedia.org/wiki/Caenorhabditis_elegans
dekhn 11y ago
C. Elegans is the greatest model organism that has ever been studied. It was specifically selected (by Sydney Brenner) as a model for its properties: it eats E. Coli, the most common model organism. So it's a model organism that lives on a model organism. it's transparent so microscopy is really easy. it always grows the exact same number of cells in the exact same place . Among those properties: first multicellular model organism to have its genome sequenced. C. Elegans continues to astound: 35% of its genes are homologous to human genes and the human forms can be used to replace the C. Elegans ones with minimal phenotypic difference. each terminally differentiated cell (of which there is a fixed number) ends up in a specific location, which were identified in a heroic effort by John Sulston Each of those cells can be targeted individually, both genetically and optically, allowing for very powerful experiments. The Nobel Prize went to Brenner, Sulston, and Horvitz for their work. the full neural connectome of the C. Elegans neural system has been mapped. RNAi was discovered in C. Elegans. OpenWorm is a project to build a virtual model of the organism. Having a complete model would require immense computation and storage, but OpenWorm is a reasonable approach. Dollar for dollar, C. Elegans research pays off better than any massive science project I know of in biology. https://en.wikipedia.org/wiki/Caenorhabditis_elegans https://en.wikipedia.org/wiki/Caenorhabditis_elegans
- hga 11y ago
  first multicellular model organism to have its genome sequenced. C. Elegans continues to astound: 35% of its genes are homologous to human genes and the human forms can be used to replace the C. Elegans ones with minimal phenotypic difference. Errr, I wonder why this is a surprise. If it respires, produces ATP, etc., why shouldn't is share common eukaryotic building blocks, that we should not be surprised are well conserved? It does sound cool, but I think I'd rather work on E. Coli than an icky worm ^_^.
  - dekhn 11y ago
    Fair criticism, although generally I think for organisms that are that far separated, you'd think the substitutability would be a bit lower given their evolutionary distance. As for the worm being icky to be honest I hated C. Elegans when I first heard about it, mainly because the primary phenotypes were "dumpy" and "uncoordinated". That said, I feel like the value of the organism exceeds the ick factor for myself and TBH I find lumps of E. Coli pretty unappealing.
T-A 11y ago
I am surprised that this was not mentioned: http://www.openworm.org/ http://www.openworm.org/
x5n1 11y ago
I have a theory that the processing that happens in the brain does not all happen by physical means confined to the brain. I think that neurons either have quantum ability of using neurons in other dimensions or somehow have access to some of the machinery that runs the universe itself. That's how we get these ideas about the universe and everything in it, because the brain taps into the computer that runs the universe. If you look at really simple organisms with a few neurons doing really complicated things, it makes you think there is something more going on there than just a few neurons firing in a neural network.
- TeMPOraL 11y ago
  Brains must be at least orchestrating those computations, or you couldn't explain all the various ways cognitive functions can be disabled with almost pinpoint accuracy by damaging the brain in specific regions. I think we know enough about brains of living things to be pretty sure all required computation is being done within the body. Last time I checked, we could pull something resembling a map of the environment out of rat's brain via fMRI.
  - mathgenius 11y ago
    I think there is a valid counter argument to what you say here. Just because we hear sound come out of the radio does not mean that this sound is created by the radio. Disabling various regions inside the radio will also cause various malfunctions. > I think we know enough about brains of living things to be pretty sure... Did you read the article? Seems like we have only a very feeble understanding of the brain.
    - TeMPOraL 11y ago
      That's why I wrote that it must be at least orchestrated, in a way that a radio orchestrates the sound by tuning in on correct frequency, amplifying and decoding (digital) or doing FM->AM conversion. I'm not saying that the original comment is for sure 100% wrong. > Seems like we have only a very feeble understanding of the brain. Yes and no. Our understanding is very selective; we definitely lack the details on everything, but we know the general picture and details of some parts - which lets us have some confidence about how the thing works. We know for instance that if brain is in fact just an antenna, it's not for anything that goes over EM spectrum, and most likely neither by any particle known to us. Otherwise we'd have figured it out already by accident - people would drop dead underground or close to (shielded) nuclear reactors. On the other hand, we can pull things that look like intermediate computation results out of brains via fMRI. This does not discard original comment's hypothesis, but lets us classify it as "extremely, extremely unlikely".

by mojoe 11y ago

IndianAstronaut 11y ago

Keep in mind that each of those neurons has over 10k genes and hundreds if not thousands are going to be expressed at any given time. Each cell is very complicated.

TeMPOraL 11y ago
It's incredibly sad that they don't talk more in high school about DNA methylation and genetic expression in general. Or at least they didn't when I was a high-schooler. It changes the perspective on DNA - from being "the recipe of life, your entire source code" to "list of functions that may or may not be active, depending on other functions, environment and whatever is or is not active in the parent mechanism that does the cell replication (hidden state; c.f. Reflections on Trusting Trust)".
- IndianAstronaut 11y ago
  The analogy to a computer is a good one. A computer may have lots of software. Installed, but only some of it is used. Sometimes the software interacts with each other.

kkylin 11y ago

The whole worm is not that many more cells (a big fraction are neurons): https://en.wikipedia.org/wiki/Caenorhabditis_elegans https://en.wikipedia.org/wiki/Caenorhabditis_elegans

dekhn 11y ago

C. Elegans is the greatest model organism that has ever been studied. It was specifically selected (by Sydney Brenner) as a model for its properties: it eats E. Coli, the most common model organism. So it's a model organism that lives on a model organism. it's transparent so microscopy is really easy. it always grows the exact same number of cells in the exact same place . Among those properties: first multicellular model organism to have its genome sequenced. C. Elegans continues to astound: 35% of its genes are homologous to human genes and the human forms can be used to replace the C. Elegans ones with minimal phenotypic difference. each terminally differentiated cell (of which there is a fixed number) ends up in a specific location, which were identified in a heroic effort by John Sulston Each of those cells can be targeted individually, both genetically and optically, allowing for very powerful experiments. The Nobel Prize went to Brenner, Sulston, and Horvitz for their work. the full neural connectome of the C. Elegans neural system has been mapped. RNAi was discovered in C. Elegans. OpenWorm is a project to build a virtual model of the organism. Having a complete model would require immense computation and storage, but OpenWorm is a reasonable approach. Dollar for dollar, C. Elegans research pays off better than any massive science project I know of in biology. https://en.wikipedia.org/wiki/Caenorhabditis_elegans https://en.wikipedia.org/wiki/Caenorhabditis_elegans

hga 11y ago
first multicellular model organism to have its genome sequenced. C. Elegans continues to astound: 35% of its genes are homologous to human genes and the human forms can be used to replace the C. Elegans ones with minimal phenotypic difference. Errr, I wonder why this is a surprise. If it respires, produces ATP, etc., why shouldn't is share common eukaryotic building blocks, that we should not be surprised are well conserved? It does sound cool, but I think I'd rather work on E. Coli than an icky worm ^_^.
- dekhn 11y ago
  Fair criticism, although generally I think for organisms that are that far separated, you'd think the substitutability would be a bit lower given their evolutionary distance. As for the worm being icky to be honest I hated C. Elegans when I first heard about it, mainly because the primary phenotypes were "dumpy" and "uncoordinated". That said, I feel like the value of the organism exceeds the ick factor for myself and TBH I find lumps of E. Coli pretty unappealing.

T-A 11y ago

I am surprised that this was not mentioned: http://www.openworm.org/ http://www.openworm.org/

x5n1 11y ago

I have a theory that the processing that happens in the brain does not all happen by physical means confined to the brain. I think that neurons either have quantum ability of using neurons in other dimensions or somehow have access to some of the machinery that runs the universe itself. That's how we get these ideas about the universe and everything in it, because the brain taps into the computer that runs the universe. If you look at really simple organisms with a few neurons doing really complicated things, it makes you think there is something more going on there than just a few neurons firing in a neural network.

TeMPOraL 11y ago
Brains must be at least orchestrating those computations, or you couldn't explain all the various ways cognitive functions can be disabled with almost pinpoint accuracy by damaging the brain in specific regions. I think we know enough about brains of living things to be pretty sure all required computation is being done within the body. Last time I checked, we could pull something resembling a map of the environment out of rat's brain via fMRI.
- mathgenius 11y ago
  I think there is a valid counter argument to what you say here. Just because we hear sound come out of the radio does not mean that this sound is created by the radio. Disabling various regions inside the radio will also cause various malfunctions. > I think we know enough about brains of living things to be pretty sure... Did you read the article? Seems like we have only a very feeble understanding of the brain.
  - TeMPOraL 11y ago
    That's why I wrote that it must be at least orchestrated, in a way that a radio orchestrates the sound by tuning in on correct frequency, amplifying and decoding (digital) or doing FM->AM conversion. I'm not saying that the original comment is for sure 100% wrong. > Seems like we have only a very feeble understanding of the brain. Yes and no. Our understanding is very selective; we definitely lack the details on everything, but we know the general picture and details of some parts - which lets us have some confidence about how the thing works. We know for instance that if brain is in fact just an antenna, it's not for anything that goes over EM spectrum, and most likely neither by any particle known to us. Otherwise we'd have figured it out already by accident - people would drop dead underground or close to (shielded) nuclear reactors. On the other hand, we can pull things that look like intermediate computation results out of brains via fMRI. This does not discard original comment's hypothesis, but lets us classify it as "extremely, extremely unlikely".