Re: Fwd: Hemispherectomy, partial brain transplant

From: Eliezer S. Yudkowsky (
Date: Mon Apr 03 2000 - 10:23:28 MDT

Anders Sandberg wrote:
> "Eliezer S. Yudkowsky" <> writes:
> > 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.

That wasn't me. That was Christopher J. Phoenix (I think - it's from memory).

> The loss of a square inch of cortex may not always be immediately
> noticeable to the person losing it, but I wouldn't recommend
> it. Calvin's ideas are not very accepted by the mainstream, and given
> my limited understanding of them it is not obvious that the transplant
> would work since the patterns are highly dependent on having the right
> subcortical afferents - without their context they are meaningless.

(FYI, there's an article on "columns" in my "MIT Encyclopedia of the
Cognitive Sciences" and it's by William Calvin. I don't know about
"accepted", but one would think that his theories are known to the mainstream.)

As far as I can tell, the primary problem with the theory is that if you
transplanted a section of cortex, or a hemisphere, we wouldn't possess
the technology to wire it into the rest of the brain. If severing the
corpus callosum works as a surgical procedure, than switching the left
hemispheres of two epileptic infants will still create a severed corpus
callosum. Transplanting a square inch just gives a square inch that's
connected only to itself and not to anything around it.

--      Eliezer S. Yudkowsky

                 Member, Extropy Institute
           Senior Associate, Foresight Institute

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