On Sun, 18 Jun 2000, zeb haradon wrote:
> The best way to cool the brain in the quickest manner would be this -
> have a row of long, sharp razor blades side by side (so that they are
> parrallel to each other), a centimeter between each of them, and each
> one cooled to a very low temperature. One press slices the brain into
> several centimeter-thick wafers.
Getting through the skull is a minor problem I presume... Or have
you removed the brain and spine???
> How irreprable would the damage be? I imagine that the super-computing
> needed to reverse ice-damage would not have such a hard time figuring out
> which half-axon in wafer X matched up with which half-axon in wafer Y, but
> there would also be some "dragging" I think - ripping a cell apart and
> smearing its contents over the blade and rest of the brain, fixing this
> would indeed be like making "cows out of hamburger", but how much of a
> factor would it be? Also, are we even going on the correct assumption, that
> faster cooling is better?
I doubt the cooling rate matters much. There is still residual brain
activity in comatose patients or patients who have been dead for hours.
Since the brain is sterile you aren't going to have bacteria consuming
anything (as would be the case in the gut). Since you are out of ATP
you can't do any breakdown (or construction) that requires energy.
So so long as the non-energy requiring enzymes in compartments like
the lysosomes remain in their compartments, not much is going to happen.
The only caveat here is whether the accumulation of CO2 in the brain
lowers the pH enough to create an acidic enough environment outside
the lysosomes to activate the enzymes that haven't been delivered
to those organelles yet. [An area where the people interested
in Cryonics should do some further study.]
I don't disagree that the razor-blade approach might cool things faster
and the computer probably could stick things back together, it seems
better however to keep the ultrastructure as intact as possible even
at the expense of a lower cooling rate, unless severe extralysosomal
degradation is occuring.
It isn't the blood(O2/glucose)-loss that damages the brain, its
the resupplying of energy resulting in excitotoxicity within the
neurons causing them to lose control of ion storage and really
make a mess of things (I'm sure Anders could provide a more
technical explanation -- there is probably several sites on the
net that discuss this as well). Since brain reanimation will be
a carefully controlled process, this is unlikely to occur. We
may have drugs within the next 5-10 years that suppress this
situation and in the more distant future nanobots within or around
neurons can obviously handle the problems.
Robert
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