Terri Schiavo Question
zarellam at removetwcny.rr.comspam
Tue Mar 29 14:34:33 EST 2005
> Perhaps a better analogy would be a brain-pithed frog (or other
> decerebrate animal preparation). You can completely destroy the brain
> of a vertebrate, leaving the spinal cord intact, and produce clear,
> seemingly "purposeful" reflex responses. That is, tickle the
> brain-pithed frog's belly and it scratches its belly. Tickle its back
> and it scratches its back. It "knows" where the stimulus is located
> and directs it response appropriately. Of course, there is no such
> "knowledge", only automatic activity. People with spinal injury have
> no knowledge or feeling or consciousness of what happens below the
> injury point even though their bodies down there can respond.
> Terri Schiavo has a lot more lower CNS function remaining than just
> the spinal level, but the fact that there does exist a very low level
> of CNS function does not automatically mean that the "person" is still
> conscious or aware or perceptive or, if you will, "alive".
But how reliably can we apply this sort of analogy to humans? The PNS is,
for lack of a better term, more specialized in some of these animals.
Whereas spinal cats, for instance, may be able to walk a treadmill, humans
cannot. It's often presumed that many complex functions are controlled in
the PNS or more "peripheral" aspects of the CNS (eg. the retina) in lower
animals, whereas such control is handled in the brain in humans. Just how
certain are we that Schiavo's responses are truly subcortical?
I'm not suggesting that it matters, really. Perhaps these are just
patterned residual responses from a damaged cortex, and are not conscious
responses to external stimuli. I just think it may be a mistake to
attribute her responsiveness entirely to subcortical mechanisms. I'm also
not suggesting that this is what you're implying, Dr. Norman, but it appears
that this may be growing sentiment among others.
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