Re: Cryonics: A question

Anders Sandberg (
Wed, 25 Jun 1997 11:05:59 +0200 (MET DST)

On Tue, 24 Jun 1997, James Rogers wrote:

> It appears to me that given the amount of time required to get the body to
> an appreciably low temperature, it would allow the chemical/ionic
> potentials in the brain to approach something resembling equilibrium.
> Since the brain structure is merely the hardware, wouldn't a brain in
> equilibrium essentially be a blank slate?

No. If your potentials were reset, you would lose your short-term memory
(and perhaps some intermediate-term memory), but not your long-term
memory, which seems to reside in synaptic strengths and connectivity
(i.e. "hardware"). People who nearly has drowned in cold rivers have
been revived after fairly long periods of no brain activity with no
loss of identity.

(Strictly speaking, a brain in total equilibrium is by definition a
dead brain, but here we are speaking more about equilibrium of
sodium, potassium and other neuroelectrically important ions. There
is also no reason not to think the revival process can't handle some
ion leakage if it can handle the other damage)

> At the very least, it seems that you should suffer significant loss
> of pre-cryo memory.

Judging from studies done on ECT patients, they might lose memory a
few months back. Not that bad for escaping death (and a good start
for an science fiction story: the protagonist awakens from biostasis
only to find out that had been murdered. The only witness was himself
and the murderer, and he can't remember who it was. So the murderer
could be *anyone* in his vicinity... ).

> Also, on a more technical side, is liquid Nitrogen capable of stopping
> ion/molecular transport, or just slowing it down?

I would say it does, since once all the water has frozen all ion
channels are blocked (and the ions themselves frozen in place). Some
diffusion and tunneling will occur, but it is likely extremely slow.
See "How Cold is Cold Enough?" by Hugh Dixon

> The neurophysiology inclined on this list may be able to answer this.

Thanks for asking about something I really do know something about...

Anders Sandberg Towards Ascension!
GCS/M/S/O d++ -p+ c++++ !l u+ e++ m++ s+/+ n--- h+/* f+ g+ w++ t+ r+ !y