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| ksoileau... |
 Posted: Tue Sep 01, 2009 8:03 pm |
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There is a surgical procedure called a hemispherectomy (http://
en.wikipedia.org/wiki/Hemispherectomy), in which half of the brain is
removed. This drastic operation is sometimes done to treat severe
epilepsy in children. Amazingly, recovery is usually near-complete.
This healing capability of the body seems (to me at least) impossible
to have been acquired through evolution, since the procedure has been
done in only the last tiny fraction of human history, hence a long
evolutionary process could not account for it.
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| J.A. Legris... |
| Posted: Tue Sep 08, 2009 6:51 pm |
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On Sep 2, 2:03=A0am, ksoileau <kmsoil... at (no spam) gmail.com> wrote:
[quote:a23a98b5fe]There is a surgical procedure called a hemispherectomy (http://
en.wikipedia.org/wiki/Hemispherectomy), in which half of the brain is
removed. This drastic operation is sometimes done to treat severe
epilepsy in children. Amazingly, recovery is usually near-complete.
This healing capability of the body seems (to me at least) impossible
to have been acquired through evolution, since the procedure has been
done in only the last tiny fraction of human history, hence a long
evolutionary process could not account for it.
Comments?
[/quote:a23a98b5fe]
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| Anthony Campbell... |
| Posted: Tue Sep 08, 2009 6:51 pm |
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On 2009-09-02, ksoileau <kmsoileau at (no spam) gmail.com> wrote:
[quote:6b1fd87958]There is a surgical procedure called a hemispherectomy (http://
en.wikipedia.org/wiki/Hemispherectomy), in which half of the brain is
removed. This drastic operation is sometimes done to treat severe
epilepsy in children. Amazingly, recovery is usually near-complete.
This healing capability of the body seems (to me at least) impossible
to have been acquired through evolution, since the procedure has been
done in only the last tiny fraction of human history, hence a long
evolutionary process could not account for it.
Comments?
[/quote:6b1fd87958]
I don't think it is necessary to invoke a special ability to recover
from hemispherectomy. This is merely an extreme example of brain
plasticity. Some 30-40 years ago it was widely held that the development
of the brain was pretty well fixed by the age of about 3, but it is
becoming clear today that the brain preserves an ability to reorganise
itself, and even to generate new neurons, at any age, though it is more
marked in childhood. Recovery after stroke illustrates this.
Another example of the same thing is the discovery of people who
suffered from hydrocephalus in childhood ('water on the brain'). The
increased pressure in the ventricles caused the brain tissue to flatten
out aganst the skull until it was just a thin layer, yet the adults'
intellectual function was quite normal -- one had obtained a degree in
mathematics.
Anthony Campbell
--
Anthony Campbell - ac at (no spam) acampbell.org.uk
Microsoft-free zone - Using Debian GNU/Linux
http://www.acampbell.org.uk (blog, book reviews,
and sceptical articles) |
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| arun neru... |
| Posted: Tue Sep 08, 2009 6:51 pm |
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On Sep 2, 11:03=A0am, ksoileau <kmsoil... at (no spam) gmail.com> wrote:
[quote:3fcaf81b54]There is a surgical procedure called a hemispherectomy (http://
en.wikipedia.org/wiki/Hemispherectomy), in which half of the brain is
removed. This drastic operation is sometimes done to treat severe
epilepsy in children. Amazingly, recovery is usually near-complete.
This healing capability of the body seems (to me at least) impossible
to have been acquired through evolution, since the procedure has been
done in only the last tiny fraction of human history, hence a long
evolutionary process could not account for it.
Comments?
[/quote:3fcaf81b54]
evolution is not expecting a surgical procedure to come and
Hemispherectomy is not the only way to severe brain. The evolution of
healing does not need a surgical procedure. |
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| John Hasenkam... |
| Posted: Fri Sep 25, 2009 7:03 am |
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"ksoileau" <kmsoileau at (no spam) gmail.com> wrote in message
news:h7l1rs$29td$1 at (no spam) darwin.ediacara.org...
[quote:a0d10d57e6]There is a surgical procedure called a hemispherectomy (http://
en.wikipedia.org/wiki/Hemispherectomy), in which half of the brain is
removed. This drastic operation is sometimes done to treat severe
epilepsy in children. Amazingly, recovery is usually near-complete.
This healing capability of the body seems (to me at least) impossible
to have been acquired through evolution, since the procedure has been
done in only the last tiny fraction of human history, hence a long
evolutionary process could not account for it.
Comments?
[/quote:a0d10d57e6]
We can survive on half a lung, quarter of a kidney, a tiny bit of liver etc
etc. It is a general trend in large organisms, lots of reserve capacity. The
surgery is remarkable, I'm not denying that. But you need to remember that
the neocortex at least, and I suspect to a lesser degree other cerebral
regions, are much more flexible than we often think. Thus, in this surgery,
if the left hemisphere is removed, it is not uncommon for speech to be
preserved because that function has already shifted to the right side of the
brain(only in children I think). There are other studies which clearly
indicate tremendous versatility in function. Eg. Lose sight and sometimes
the auditory nerves will form new connections with the visual cortices. This
possibly explains echolocation in blind humans. Nor is that strange because
as recent research has demonstrated even at the primary sensory level the
regions for touch, vision etc, are directly interconnected, rather than just
being connected through "multi modal modules" and all that jumbo.
See, we really don't understand very much about CNS organisation so it is
dangerous to even think too hard about how or why the above things are
happening. We're getting there and it is great fun watching it unfold. For
example, even stranger than the above are the results of "constraint induced
movement therapy". Google that phrase, fascinating work by Taub.
PS: the recovery is often remarkable but there are also often a series of
subtle deficits such as slowness of speech, reduced intelligence, a limp on
the contra side of the body. Don't just rely on the news releases which
sensationalise all this, try and dig deeper.
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