Billy Brown writes:
> Well, if you are talking about incinerating the brain, or dissolving it in
> acid, or something equally drastic, I agree. But the kinds of injuries that
> actually occur with any significant frequently aren't nearly that severe.
You surely speak from a rich basis of experience, here.
> For example, a few hours of ischemic injury would leave a quiet recognizable
> brain. You've got lots of molecules that have been degraded in some way
> (denatured proteins, etc.), but the general structure of the cells is
> preserved and most of the damaged components are pretty much where they
> started. If you understand what healthy cells are supposed to look like,
> and you know the chemical pathways that cause the damage, restoring the
> tissue to its original state should not be a big deal.
Of what fucking value is an almost undamaged brain if I cannot perfuse
it? If I cannot load it with sufficient amount of cryoprotectants, and
hence have to do a straight freeze?
> Hmm. I rather suspect that our real disagreement is here. IMO, current
> evidence adequately supports the assumption that information storage in the
> brain is not localized - i.e. that each bit is stored as part of the pattern
> of interconnections of a very large number of neurons, rather than in the
> state of some particular part of a single cell.
Sometimes microlesions do have a visible impact. But this is
irrelevant, because the damage is not focal. You have a veil of
damage, on all scales (from molecular to macro) spread over the entire
brain. Optically, it even looks relatively good. You have to look at
EM micrographs (ultrastructural) level to see what horrible things
happen there.
> That means that you don't need to put every atom exactly back in its
> original position to get a successful reconstruction. The important
Speaking about atomic resolution in such context is the ultimate joke.
> features are relatively large, highly redundant structures containing vast
> numbers of molecules. Obliterating those structures beyond recognition will
> require far more damage than you would normally see - you'd have to drop the
> brain in a blender, or do something equally drastic. I'm not sure how much
> natural decay it would take, but it seems obvious that we're talking about
> days or weeks rather than hours.
Ultrastructurally, you're mush after 24 h of normothermia.
> If, however, you believe that all of the fine structure within an individual
> cell is important, that would make the problem much more difficult. Then
> you would have to get each molecule back to exactly its original position
> and state, so the amount of damage required to prevent reconstruction would
> be much lower. I still think, however, that you make insufficient allowance
> for the fact that reconstruction isn't limited to just looking at the frozen
> tissue and following simple atom-shuffling algorithms.
Belief in reversibility of anything can become a religion.
This archive was generated by hypermail 2b29 : Thu Jul 27 2000 - 14:04:06 MDT