X-Message-Number: 8525
From: Anders Sandberg <>
Newsgroups: sci.cryonics
Subject: Re: Memories
Date: 02 Sep 1997 16:15:26 +0200
Message-ID: <>

References: <> 
<>

 writes:

> If it is true that memories are chemicals, then when you die, these
> chemicals should disintegrate. That means all your memories - of who you
> ARE, will be lost. 

This is likely wrong. Current neuroscientific opinion is that long-term
memory is based on structural changes in the brain, not chemicals. 
Short-term memories are likely electrochemical in nature, and would
disintegrate if there was time for chemical degradation (the critical
period might be on the order of tens of minutes, judging from LTP
data and reports of people revived after near-drowning). These
short-term memories are then gradually consolidated into long
term memory through at present little known processes, but the
result seems to be changes in synaptic shape, size and number
which are permanent. 

So if cryonics can preserve the synapses (and the connectivity of 
the brain) long-term memories ought to be preserved. Short-term
memories will likely disappear, but a limited amnesia of the
events just before being suspended is a small price to pay if the
process works. The electron microscope photos of cryopreserved brain 
tissue that Mike Darwin showed me when I visited him suggested that
the synapses were well preserved, but there might be trouble with 
preserving connectivity with present methods. 

Two references:

Dyson SE, Jones DG: Synaptic remodelling during development and
maturation: Junction differentation and splitting as a mechanism
for modifying connectivity. Dev Brain Res 1984;13;125-137

Greenough WT, Bailey CH: The anatomy of memory: Convergence of
results across a diversity of tests. Trends Neurol Sci 1988;11;142-147

I just noticed there is some relevant information in the FAQ
too, at 
http://www.cs.cmu.edu/afs/cs/user/tsf/Public-Mail/cryonics/html/0018.2.html#2-7

 -- 
 -----------------------------------------------------------------------
 Anders Sandberg                                      Towards Ascension!
               http://www.nada.kth.se/~nv91-asa/main.html
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