X-Message-Number: 21235
From: 
Date: Sun, 23 Feb 2003 07:26:34 EST
Subject: Building back a brain

--part1_16.2d18eeb7.2b8a17fa_boundary
Content-Type: text/plain; charset="ISO-8859-1"


I think there is a large difference between the difficulty to build back a 
brain such as it is seen by most cryonicist and the reality. It seems that 
all the brain information is stored in the neuron connectivity, particularly 
at the synaptic buttons. Unfortunately, these are dissolved/digested in less 
than 2 hours. What remain, the neuron bodies can display a coordinated 
electric response by capacitive effect, but the brain is erased at a very 
deep level.

What remains is a soup of small decay products dispersed by Brownian motion. 
If you get a 3D map of these elements and use a very powerful computer, you 
may figure out what was the original structure.

Imagine we have a neuron chain: A-B-C-D, We are pretty sure that the link A-B 
is strongly conductive, C-D seems to be so too. On the other hand, B-C can be 
built back as either a strong or a weak link. From what we know from the 
other links, we deduce that the right answer is a strong link. Now, B-C may 
be millimeters away from the other links, that seems a big problem for a 
purely nanosystem. The necessary information network seem well out of reach 
for a system made of small units.

The real problem is far worst than that: each neuron is connected to 
thousands of other and the strength of a link could be deduced only from 
thousands of other. This is a linear system made from may be 3,000 equations, 
each with 3,000 unknowns. This is a large matrix, a modern PC would be up to 
the job, but there may be ten trillions problems of this kind to solve in a 
brain. The world computing power, 3  or 40 years from now may solve that, but 
even atomic scale circuits will never cram that power in a tea spoon of gray 
goo.

Recovering from death will ask for titanic systems, they may have nanoscale 
parts but be ready to rent a large building to shelter them.

Yvan Bozzonetti.

--part1_16.2d18eeb7.2b8a17fa_boundary

 Content-Type: text/html; charset="ISO-8859-1"

[ AUTOMATICALLY SKIPPING HTML ENCODING! ] 

Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=21235