John K Clark (
Tue, 24 Jun 1997 22:01:43 -0700 (PDT)


On Tue, 24 Jun 1997 James Rogers <> Wrote:

>How does cryonics preserve the information in the brain?

We don't know for a fact that it does, but there is reason for optimism.

>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.

Electro-chemical circuits in the brain are almost certainly not used for
long term memory, people who have survived powerful electrical shocks can
remember little about the 10 minutes or so before their accident but their
long term memory is not harmed. The most important storage mechanism of the
brain is thought by most to be Long Term Potentiation ( LTP). It theorizes
that memory is encoded by varying the strength of the 10^14 synapses that
connect the 10^11 neurons in the human brain. We now know that when one
synapse undergoes LTP it spreads out to other synapses (the LTP signal is
sent by the diffusion of nitric oxide). This means there must be a large
amount of redundancy in the storage mechanism of memory and that could help
a lot if we want to repair a badly damaged frozen brain.

>Since the brain structure is merely the hardware, wouldn't a brain
>in equilibrium essentially be a blank slate?

LTP involves a change in the structure of synapses.

>is liquid Nitrogen capable of stopping ion/molecular transport, or
>just slowing it down? If there was small but finite transport
>activity, it would put a "shelf-life" on information stored in a

Chemical reactions at liquid Nitrogen temperatures would be so slow that the
damage from natural background radiation would probably be more important.
Even so, your shelf life should be hundreds if not thousands of years.
Of more concern to me are non technical questions, like will I really remain
at liquid Nitrogen temperature until the age of Nanotechnology and will
anybody or anything think I'm worth the trouble of reviving, the cost, like
everything at that time, would not be much but it would not be zero.

John K Clark

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