processing capability of the spinal cord

Walter Eric Johnson wej3715 at fox.tamu.edu
Sun Dec 6 20:24:20 EST 1998


Richard Norman (rsnorman at mw.mediaone.net) wrote:
: >"According to a book I
: >read last Christmas (the chapters on neuroscience anyway)
: >the spinal cord provides a very large portion of the processing
: >required by many insects.  I asked a recent Ph.D. in neuroscience
: >about this and he claimed it was nonsense
: > <remainder snipped>
: 
: Technically, insects (like all invertebrates) have no spine and hence no
: spinal cord!

One of these days I'm going to remember that.  That's the third time
I have been caught on that error. 

: Actually, they do have a longitudinal nerve cord with a
: ganglion in each segment. It is true that the insect brain contains far
: more neurons than all the nerve cord ganglia combined.  Nevertheless,
: the segmental ganglia can produce a significant amount of complex,
: coordinated behavior.  Headless insects can locomote, ventilate
: their trachea, and conduct reproductive activity.  The classic example
: is a praying mantis -- during mating  the female sometimes eats the
: head off the male, but that does not stop copulation.  In fact it can
: remove inhibitory controls and allow the male to continue with more
: vigor!
: 
: As for vertebrate animals, do you know the expression "running around
: like a chicken with its head cut off"?

I wonder what neural processes in humans might continue for a little
while past death.  Would the loss of blood supply pretty much shut
down the neurons in the spinal column about as fast as we lose
consciousness?  How long do we maintain reflexes?  For example, 
how long after death would one find the Babinski reflex?

Eric Johnson



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