4 ms·

I'd suggest focusing on reattaching people's own severed spinal chords, to perfect the procedure before doing something as risky and speculative as a whole head

I'd suggest focusing on reattaching people's own severed spinal chords, to perfect the procedure before doing something as risky and speculative as a whole head transplant. If he can demonstrate that he can reliably reconnect all the correct nerves in one person's spinal chord, it would be a major breakthrough for millions of patients with spinal chord injuries, and then we can begin talking about connecting other people's, which I assume have different "pin-outs".

david-given 12y ago
Fixing a broken spinal chord is probably rather more difficult (based on my extensive and indepth knowledge of the subject [ * ]), as there's likely to be a substantial section of damaged chord --- crushed, for example. A clean cut through an undamaged chord would provide two relatively undamaged surfaces. I have heard of work in regenerating severed spinal chords in rats. I'd be more inclined to be worried about whether the neurons on one side can usefully bind to the neurons on the other. AFAIK the nerve mapping in the spinal chord is more or less random. The rat experiment wouldn't test this, of course. [ * ] Disclaimer: while I have in-depth and extensive knowledge of some subjects, this is not one of them.
- shiggerino 12y ago
  That makes sense, but as you say, the clean cut might not help the mapping problem. Even if you can somehow figure out which ones belong where that must be some very challenging microsurgery. Maybe it would be possible to make a electronic, prosthetic section of spine that can be reconfigured on the fly, a bit like an FPGA, that might be useful for both injuries (where a damaged section needs to be replaced) and clean cuts with unknown mapping. Unfortunately these kinds of brain-computer interfaces seem prone to scarring, weakening the signal over time.
  - david-given 12y ago
    It's probably easier to just let them hook up randomly and then stimulate the brain into relearning the mappings. Infants do this as a matter of course (that's what a lot of the random flailing babies do is for). An adult brain may need a substantial amount of chemical help, though. Ah, here's a short article on the work with rats: http://www.iflscience.com/brain/new-drug-boosts-nerve-regrowth-rats-spinal-cord-injuries http://www.iflscience.com/brain/new-drug-boosts-nerve-regrow...

david-given 12y ago

Fixing a broken spinal chord is probably rather more difficult (based on my extensive and indepth knowledge of the subject [ * ]), as there's likely to be a substantial section of damaged chord --- crushed, for example. A clean cut through an undamaged chord would provide two relatively undamaged surfaces. I have heard of work in regenerating severed spinal chords in rats. I'd be more inclined to be worried about whether the neurons on one side can usefully bind to the neurons on the other. AFAIK the nerve mapping in the spinal chord is more or less random. The rat experiment wouldn't test this, of course. [ * ] Disclaimer: while I have in-depth and extensive knowledge of some subjects, this is not one of them.

shiggerino 12y ago
That makes sense, but as you say, the clean cut might not help the mapping problem. Even if you can somehow figure out which ones belong where that must be some very challenging microsurgery. Maybe it would be possible to make a electronic, prosthetic section of spine that can be reconfigured on the fly, a bit like an FPGA, that might be useful for both injuries (where a damaged section needs to be replaced) and clean cuts with unknown mapping. Unfortunately these kinds of brain-computer interfaces seem prone to scarring, weakening the signal over time.
- david-given 12y ago
  It's probably easier to just let them hook up randomly and then stimulate the brain into relearning the mappings. Infants do this as a matter of course (that's what a lot of the random flailing babies do is for). An adult brain may need a substantial amount of chemical help, though. Ah, here's a short article on the work with rats: http://www.iflscience.com/brain/new-drug-boosts-nerve-regrowth-rats-spinal-cord-injuries http://www.iflscience.com/brain/new-drug-boosts-nerve-regrow...