4 ms·

Neurosurgeons have been using hypothermia (cooling down the body) and circulatory arrest (stopping the heart) to treat complicated brain aneurysms since the 198

Neurosurgeons have been using hypothermia (cooling down the body) and circulatory arrest (stopping the heart) to treat complicated brain aneurysms since the 1980's. Some of the outcomes have been very good. http://ether.stanford.edu/library/neuroanesthesia/SNACC%20Reading%20List%20articles/Spetzler_Aneurysms%20of%20the%20basilar%20artery%20treated.pdf http://ether.stanford.edu/library/neuroanesthesia/SNACC%20Re... When a person is in that state, they have no signs of life - no heartbeat and no blood to the brain, yet a significant portion of the time, they do well. From the article, it looks like they have done this for up to 50 minutes. " The median duration of complete arrest in our series was 11 minutes; the range was 7 to 53 minutes. This is consistent with reports from other neurological surgeons who have employed extracorporeal circulation for intracranial vascular surgery "

nefitty 7y ago
I wonder how different the experience of waking up from induced hypothermia is from, say, a coma. From my understanding, in a coma there is sometimes brain activity, up to the point that some people end up with Locked-in syndrome(LIS). An example is Martin Pistorius, who has vivid memories of his time in his pseudocoma. That means his sense of self was intact throughout that experience. That colors what it feels like to "escape" from the coma. In dreams, we usually have a sense of self, i.e. we "come back" to reality. There are also people who experience the subjective Near-death experience (NDE) which sometimes involves bodily detachment, etc. but presumably this NDE feels like it's occurring to that person's self. When under anaesthesia, waking up from it is more like waking up from a really deep nap, and from my experience, is easy to integrate. Now, when waking up from induced hypothermia, does the brain slowly kick on different modules? Does the brain snap back to the last thought the person was having? To use a programming analogy, does the brain save state in a physical way? Or is it like restarting a computer fresh? This is such a cool technique. Thank you for sharing info on it.
- pmoriarty 7y ago
  "An example is Martin Pistorius, who has vivid memories of his time in his pseudocoma. That means his sense of self was intact throughout that experience." Or they could just be false memories.
  - thrownblown 7y ago
    6 years of false memories? (edit: corrected the duration of his LIS)
    - agumonkey 7y ago
      I remember the movie about LIS.. I couldn't bear to watch it. 6 years of it is beyond insane.
    - asveikau 7y ago
      If 6 years had passed with limited sensory input, and you were pretty sure you remembered all of it, how would you know if that's true? How much detail do we really remember of our own last 6 years of fully awake, conscious existence not spent in such a state? I feel like once you get to such a length of time you can't trust your own memory of it. Obviously he could know enough to say "I was conscious during some point of that time window" but measuring it would be hard.
TaupeRanger 7y ago
The hard problem is when electrical activity stops in the brain, which can continue for a time even without blood flow.
- spurgu 7y ago
  Why is this a problem (or am I dumb)?
  - mikelyons 7y ago
    Our current understanding seems to be that the electrical activity of the brain is what maintains the mind-consciousness system. (From a physical/materialist pov)
    - pan69 7y ago
      I assume OP wants to know why we can't provide electrical activity manually.
      - mikelyons 7y ago
        This seems to be one of the ancillary benefits of Neuralink, although I could be wrong, I'm not super familiar with their entire road-map.
    - hanniabu 7y ago
      So in other words it's like RAM, just the power off and all is lost.
      - mikelyons 7y ago
        Life must be sustained, once it is lost, it seems that there is a bell that cannot be un-rung. However, our understanding of how much energy it takes to sustain life at a minimum seems to keep decreasing, like higher efficiency RAM in low-power mode.
    - 7y ago
agumonkey 7y ago
IIRC some girl survived extremely long brain arrest after drowning in an ice lake. She cryo-preserved herself unwillingly.

nefitty 7y ago

I wonder how different the experience of waking up from induced hypothermia is from, say, a coma. From my understanding, in a coma there is sometimes brain activity, up to the point that some people end up with Locked-in syndrome(LIS). An example is Martin Pistorius, who has vivid memories of his time in his pseudocoma. That means his sense of self was intact throughout that experience. That colors what it feels like to "escape" from the coma. In dreams, we usually have a sense of self, i.e. we "come back" to reality. There are also people who experience the subjective Near-death experience (NDE) which sometimes involves bodily detachment, etc. but presumably this NDE feels like it's occurring to that person's self. When under anaesthesia, waking up from it is more like waking up from a really deep nap, and from my experience, is easy to integrate. Now, when waking up from induced hypothermia, does the brain slowly kick on different modules? Does the brain snap back to the last thought the person was having? To use a programming analogy, does the brain save state in a physical way? Or is it like restarting a computer fresh? This is such a cool technique. Thank you for sharing info on it.

pmoriarty 7y ago
"An example is Martin Pistorius, who has vivid memories of his time in his pseudocoma. That means his sense of self was intact throughout that experience." Or they could just be false memories.
- thrownblown 7y ago
  6 years of false memories? (edit: corrected the duration of his LIS)
  - agumonkey 7y ago
    I remember the movie about LIS.. I couldn't bear to watch it. 6 years of it is beyond insane.
  - asveikau 7y ago
    If 6 years had passed with limited sensory input, and you were pretty sure you remembered all of it, how would you know if that's true? How much detail do we really remember of our own last 6 years of fully awake, conscious existence not spent in such a state? I feel like once you get to such a length of time you can't trust your own memory of it. Obviously he could know enough to say "I was conscious during some point of that time window" but measuring it would be hard.

TaupeRanger 7y ago

The hard problem is when electrical activity stops in the brain, which can continue for a time even without blood flow.

spurgu 7y ago
Why is this a problem (or am I dumb)?
- mikelyons 7y ago
  Our current understanding seems to be that the electrical activity of the brain is what maintains the mind-consciousness system. (From a physical/materialist pov)
  - pan69 7y ago
    I assume OP wants to know why we can't provide electrical activity manually.
    - mikelyons 7y ago
      This seems to be one of the ancillary benefits of Neuralink, although I could be wrong, I'm not super familiar with their entire road-map.
  - hanniabu 7y ago
    So in other words it's like RAM, just the power off and all is lost.
    - mikelyons 7y ago
      Life must be sustained, once it is lost, it seems that there is a bell that cannot be un-rung. However, our understanding of how much energy it takes to sustain life at a minimum seems to keep decreasing, like higher efficiency RAM in low-power mode.
  - 7y ago

agumonkey 7y ago

IIRC some girl survived extremely long brain arrest after drowning in an ice lake. She cryo-preserved herself unwillingly.