5 ms·

Can anyone here better explain the hand-wavy stuff about re-connecting the spinal cord? I (incorrectly or not) think of the spinal cord as bunch of wires, presu

Can anyone here better explain the hand-wavy stuff about re-connecting the spinal cord? I (incorrectly or not) think of the spinal cord as bunch of wires, presumably that have to be connected to the correct counterpart individually. In the article they talk about reconnecting the spinal column in ~2 minutes, which seems to rule that out.

dmitrygr 12y ago
They explained that a few compounds including polyethylene glycol can help glue the nerves together and function (transmit electrical impulses), as they claim, at 10% efficiency. They then state that better compounds exist and that efficiency can also be improved with some other chemicals. At least so I read it
- mbenjaminsmith 12y ago
  Yeah I caught that. I'm wondering more about the alignment problem. You wouldn't, for example, just glue a severed bundle of fiber optics back together without reconnecting each strand individually.
  - dmitrygr 12y ago
    Why not? Brains adapt very well. Monkeys given a brain implanted electrodes that control a mechanical arm learned to use it in days. I am pretty sure that with some therapy you could use all your limbs quite well if i swapped the neurons that go to them haphazardly. And it would probably take months, not years of therapy http://en.wikipedia.org/wiki/Neuroplasticity http://en.wikipedia.org/wiki/Neuroplasticity
  - jonmrodriguez 12y ago
    If you connected through a silicon interposer you could use an FPGA or something similar on the silicon to rearrange and possibly even transcode the signals as needed. Some sort of precise robot similar to a wire-bonding machine could make bonds between nerve ends and pads on the silicon. And then maybe fill the whole area with something solid like epoxy so the bonds don't move or loosen?
    - fractallyte 12y ago
      In other words, an API?
      - indiv0 12y ago
        More like a patch panel.
- deleted 12y ago
  [deleted]
arm55 12y ago
In theory, nerve connection is quite easy. Put two nerves of the same type right up next to each other and they will fuse and form a continuous signal transduction pathway. However, the success rate for this is somewhere on the order of 80%. Assuming there are ~100 connections to be made, 0.80^100 isn't very enticing. Perhaps using the compounds he talks about can increase the success rate, but this is still on fairly shaky grounds.
- dmitrygr 12y ago
  http://en.wikipedia.org/wiki/Neuroplasticity http://en.wikipedia.org/wiki/Neuroplasticity
- mbenjaminsmith 12y ago
  Actually, if I'm reading wikipedia correctly, there are only 62 connections that need to be made. While that doesn't help with the error rate it seems feasible to make that many connections individually in a short period of time, if that is in fact what they're doing.
  - shutupalready 12y ago
    > if I'm reading wikipedia correctly, there are only 62 connections For others, here's the Wikipedia link: http://en.wikipedia.org/wiki/Spinal_nerves http://en.wikipedia.org/wiki/Spinal_nerves I'm surprised that it's so few (31 pairs of spinal nerves). I would have imagined that there would be thousands and thousands of nerves. Since we certainly have more than 62 sensory inputs and motor outputs in the trunk of our body, I assume that those 62 nerves hide quite a lot complexity.
  - icegreentea 12y ago
    The spinal nerves (by and large) originate in the spinal cord at their level of origin. That is to say that if you severed the spinal cord at some point, you could not 'split out' the connections corresponding to the lower spinal nerves from the overall bundle. Amongst other things, the spinal cord also contains neurons that form closed circuits without reaching the brain (these make up your reflexes). So, if you transplanted the head and spinal cord, then use, you could somehow make '62 connections'. If you transplanted 'the head' you would have to join the entire spinal cords. Finally, each nerve is really 'a cable bundle', so the process of joining them is kinda tricky, and beyond the scope of my knowledge. Needless to say, the authors of the paper think that it can work. Their references likely can point you in the right direction.

dmitrygr 12y ago

They explained that a few compounds including polyethylene glycol can help glue the nerves together and function (transmit electrical impulses), as they claim, at 10% efficiency. They then state that better compounds exist and that efficiency can also be improved with some other chemicals. At least so I read it

mbenjaminsmith 12y ago
Yeah I caught that. I'm wondering more about the alignment problem. You wouldn't, for example, just glue a severed bundle of fiber optics back together without reconnecting each strand individually.
- dmitrygr 12y ago
  Why not? Brains adapt very well. Monkeys given a brain implanted electrodes that control a mechanical arm learned to use it in days. I am pretty sure that with some therapy you could use all your limbs quite well if i swapped the neurons that go to them haphazardly. And it would probably take months, not years of therapy http://en.wikipedia.org/wiki/Neuroplasticity http://en.wikipedia.org/wiki/Neuroplasticity
- jonmrodriguez 12y ago
  If you connected through a silicon interposer you could use an FPGA or something similar on the silicon to rearrange and possibly even transcode the signals as needed. Some sort of precise robot similar to a wire-bonding machine could make bonds between nerve ends and pads on the silicon. And then maybe fill the whole area with something solid like epoxy so the bonds don't move or loosen?
  - fractallyte 12y ago
    In other words, an API?
    - indiv0 12y ago
      More like a patch panel.
deleted 12y ago
[deleted]

arm55 12y ago

In theory, nerve connection is quite easy. Put two nerves of the same type right up next to each other and they will fuse and form a continuous signal transduction pathway. However, the success rate for this is somewhere on the order of 80%. Assuming there are ~100 connections to be made, 0.80^100 isn't very enticing. Perhaps using the compounds he talks about can increase the success rate, but this is still on fairly shaky grounds.

dmitrygr 12y ago
http://en.wikipedia.org/wiki/Neuroplasticity http://en.wikipedia.org/wiki/Neuroplasticity
mbenjaminsmith 12y ago
Actually, if I'm reading wikipedia correctly, there are only 62 connections that need to be made. While that doesn't help with the error rate it seems feasible to make that many connections individually in a short period of time, if that is in fact what they're doing.
- shutupalready 12y ago
  > if I'm reading wikipedia correctly, there are only 62 connections For others, here's the Wikipedia link: http://en.wikipedia.org/wiki/Spinal_nerves http://en.wikipedia.org/wiki/Spinal_nerves I'm surprised that it's so few (31 pairs of spinal nerves). I would have imagined that there would be thousands and thousands of nerves. Since we certainly have more than 62 sensory inputs and motor outputs in the trunk of our body, I assume that those 62 nerves hide quite a lot complexity.
- icegreentea 12y ago
  The spinal nerves (by and large) originate in the spinal cord at their level of origin. That is to say that if you severed the spinal cord at some point, you could not 'split out' the connections corresponding to the lower spinal nerves from the overall bundle. Amongst other things, the spinal cord also contains neurons that form closed circuits without reaching the brain (these make up your reflexes). So, if you transplanted the head and spinal cord, then use, you could somehow make '62 connections'. If you transplanted 'the head' you would have to join the entire spinal cords. Finally, each nerve is really 'a cable bundle', so the process of joining them is kinda tricky, and beyond the scope of my knowledge. Needless to say, the authors of the paper think that it can work. Their references likely can point you in the right direction.