[SL4] Fwd: Hemispherectomy, partial brain transplant

From: Eliezer S. Yudkowsky (sentience@pobox.com)
Date: Sun Apr 02 2000 - 17:56:59 MDT

You know, no matter how much time I spend thinking about the
Singularity, suggestions like these still give me the chills.

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attached mail follows:

At 03:11 PM 3/31/00 EST, DonSaxman@aol.com wrote:
>And speaking of auxiliary, here's an auxiliary train of thought that might
>help us answer the question. Serious trauma can literally destroy over 50%
>of a human's brain, often with profound personality degradation, but not
>necessarily resulting in death. What if instead of destroying half a brain,
>the half-brain was transplanted into a new body. Medical technology is
>getting close to being able to accomplish this, and I suspect that it would
>be possible with existing surgical techniques if the donor body was a clone.
>Would that be "migrating" your (very much degraded) consiousness into two
>bodies? I suspect so, but what do you-all think? if not, the possibility of
>migration to non-organic via a cyborg auxiliary brain is much less appealing.

Since at least 1950, "hemispherectomy" (the surgical removal of half the
brain) has been used in children for hemiplegia and intractable epilepsy.
>From http://www.c3.hu/~mavideg/jns/642696june1.html "The operation
eliminated or reduced seizures in 70% to 80% of patients. In the majority of
reported cases, surgery improved the patients' development, led to increased
intelligence quotient scores, and often eliminated profoundly negative
behavior. Perioperative mortality rates were 5% to 6% in case series from
1950 to 1970.[58] Long-term morbidity and mortality, however, gave rise to a
much greater concern."

So I got to thinking: What if Calvin is right, and our cortex has lots of
small areas that are independently active and compete with each other to
produce the overall thought? What if we could cut out a square inch of
cortex (containing many complete active-areas) and implant it in another
brain? That would leave the donor almost unchanged... but the recipient
would have access to some of the thoughts and memories, and maybe even
patterns of thought, of the donor, if the thoughts were strong enough to
spread through the rest of the brain and become conscious. What if I cloned
myself and gave the infant clone a square inch of my brain? Would the
thought patterns propagate and train the new brain? It wouldn't be me, of
course, but mentally it might be about as close as an identical twin. (I'd
rate that about 15-20% on the scale of "me"-ness.) This is an experiment
that in theory we could do within ten years.

I wouldn't think I was still fully "me"* if half my brain were destroyed.
I'd be a different person with some of the same memories and thought
patterns. Still, if I had to choose between losing half a brain and being
fully dead, I'd choose the half-brain option as long as my function wasn't
degraded too much (e.g. IQ not below 85).

* I view identity on a continuum. I'm mostly still "me" if I'm drunk or
sleep-deprived. Ten years from now I'll be maybe 75% the same "me". A good
upload should preserve 90% or better. People who use cocaine to help them
work already accept more changes, for less benefit, than uploading will
likely entail.

My consciousness restarts every time I wake up. Consciousness is not nearly
as important as it would like us to think it is. It's simply one
significant feature of my brain--it tells me what I'm thinking, just as
emotion tells me how I'm feeling. My guess is that any running system(s)
that had my memories and thought patterns and circuitry (physical or
simulated) would have "my" consciousness. (This email can be copied to many
computers. So can a mind. Which of you is reading the "real" email? It's
a stupid question.)


Chris Phoenix  cphoenix@best.com  http://www.best.com/~cphoenix 
Work (Reading Research Council): http://www.dyslexia.com
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