X-Message-Number: 3329
From:  (David Stodolsky)
Subject: CRYONICS: Re: Brain scanning, reply to Marvin Minsky
Date: Sat, 22 Oct 94 12:26:44 +0100 (MET)

In Message: #3318 - Brain scanning, reply to Marvin Minsky
Brian Wowk <> writes:  
>         Improving on the above resolution would require stronger
> gradients.  This is not possible for *external* gradient coils
> because prohibitively large currents would be induced by dB/dt in
> peripheral areas.  You would therefore have to put not just rf coils,
> but high-current gradient coils inside the brain as well, which is not
> something I care to speculate on.

If we accept that memory information is exclusively stored in the
gray matter, there might be a way to do this. If the
cortex is "unfolded" we have a sheet of material of roughly
a square meter and less than a centimeter thick. Thus, we can move from
a 3D analysis to a "2.5" D analysis. 

I am not suggesting that the cortex actually be unfolded, but a probe
containing high-current gradient coils could certainly be inserted
into the folds of the cortex without much damage. Then a large number
of "snapshots" of very small sections of cortex could be taken and
later assembled in a computer. The probe would be at the end of a robot
arm, so accurate positional info would be easy to get. A little overlap
in the pictures would ease final alignment.

I am not sure this would be as easy to do with the motor cortex, but
having to learn again how to ride a bicycle, etc. would probably be
acceptable. Other motor learning might be important to support cognitive
activities, however, so this could be show stopper. How much of the
"long range" connections in the brain would be captured by the above
approach is also an open question.

David S. Stodolsky, PhD               Internet: 
Peder Lykkes Vej 8, 4. tv.      (C)         Tel.: + 45 32 97 66 74
DK-2300 Copenhagen S, Denmark                Fax: + 45 32 84 08 28

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