X-Message-Number: 7848
Date: Thu, 13 Mar 1997 09:11:07 -0800 (PST)
From: Joseph Strout <>
Subject: Re: timescale of cryonics & uploading

On Thu, 13 Mar 1997, Jan Coetzee (#7841) wrote:

> "I find the prospect of repairing the brains
> and bodies of those now frozen to be much more daunting than copying their
> brains into artificial devices. " 
> 
> Is this not a contradiction? After all in order to copy a neural structure
> to a machine it must be repaired first? 

Not at all.  Far easier to extract the data as it is, and "repair" it as
data, than to repair the physical device and then tear it apart extracting
data.

And in #7844, Garret Smyth wrote:

> Learning is not simply a matter of whether there is a connection between
> one cell and another, but how easily the synapses are triggered.

Maybe, maybe not.  I suspect that changes in synaptic efficacy are
short-term only; they may lead to consolidation in long-term memory, but
they are not long-term memory itself.  Long-term memory is probably stored
in the number (and position) of synapses.  This has been demonstrated in
sea slugs at least, and humans are not so different.  ;)

> To copy a brain in fine detail - and to upload a "person" as I'm sure
> even die hard uploaders will admit, will require a pretty high
> definition copy - would need a scan of the brain almost molecule by
> molecule. This would be so that ion gates and chemical receptors would
> not only be recorded numerically but also in terms of position. 

If you get down to the scale of the position and phosphorylation states of
individual channels etc., then you're almost certainly talking about
short-term properties.  These can probably be ignored.  As a result,
you may lose the last few hours or days, but not any long-term memories or
other personality traits.

> On top of this, current suspensions are pretty disruptive, so the
> scanning will have to be done on an even finer scale so that
> calculations can be made as to where things should have been.

I'm not sure I see how a finer scale helps the reconstruction problem.
Disruption happens on two major scales: ice crystals shove things aroung
locally, and cracking makes major fissures.  Cracking is easy to deal
with; you've got a lot of pattern on either side of the crack, which is
sure to line up unambigously after basically a linear transformation.  Ice
crystals cause smaller disruptions, but more numerous, and may be more
tricky.  But if you look more closely, you don't get any more information
about that.  FWIW, I've estimated that about 10 nm resolution is what
you'd probably need for uploading.  That's should be within an order of
magnitude or two, at least!

> Okay, MRI might be able to do this scanning

No, MRI can't get anywhere near the resolution needed.  And it looks like
it never could; some laws of physics get in the way of extracting that
much information nondestructively.  Probably the only way to get it will
be to destroy the brain slice by slice, examining each one as you go.  I
prefer electron microscopy for this, but Eugene suggests that AFM arrays
might do the job better.

> but the knowledge needed to calulate what the information about fine
> brain structure means would need a knowledge of so much greater than we
> have know that it we'll probably need to have done a plethora of
> nano-scale experiments to get there.

Yes, we need to know a lot more, but no, we don't need nanotechnology to
get there (if that's even what you meant to imply).  Current electron
microscopes give us plenty of resolution; the problems are theoretical and
practical (e.g., handling microscopic tissue slices is laborious and
time-consuming).  You'd be surprised how much you can learn just from a
confocal or two-photon optical microscope, too.

> On top of this, gung ho neuro-patient that I am, I remain to be
> convinced that an uploaded copy of me would actually be me. Wimpy though
> you may think this point of view, you have to agree that my uploaded
> copy (version) would agree with me and so consider its ancestor cruelly
> murdered by the people that did the upload. So beware of angry robots
> that answer to my name seeking vengeance! 

On what basis would your upload not be you?  

It would be fun if this actually occurred...  I'd say to you, "Remember
when we had that conversation on cryonet?" and the upload would say, "Sure
I do, we said... oops, I mean, I have my *former self's* memories of that,
and you and my former self said..."  Later, I might say, "Who's this
picture of?"  and you'd say "That's my mo-- er, my former self's mother!" 
And said person, if still around, might say "Garret dearie, give your
mother a nice hug!" and you'd have to say "I'm sorry ma'am, but you're not
my mother, though I remember when you used to make my former self
crumpets, for which I thank you on his behalf."  It gets pretty
ridiculous. I suspect that after a few months of this, you'd give up and
admit that you're really the same person you were before!

Cheers,
-- Joe

,------------------------------------------------------------------.
|    Joseph J. Strout           Department of Neuroscience, UCSD   |
|               http://www-acs.ucsd.edu/~jstrout/  |
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