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why does brain impact cause unconsciousness?

Douglas Fitts dfitts at carson.u.washington.edu
Sun Sep 26 10:06:47 EST 1993


Michael Levin writes:
>>     Here are my thoughts on the subject of why brain impact causes
>>unconsciousness, and if anyone has any ideas on this, please let me
>>know. I am wondering: consider the lightest shock to the head (of a
>>human, or a mammal in general) which is sufficient to cause
>>unconsciousness of the temporary variety (being "knocked out"). Is
>>this kind of shock really so traumatic to the brain as to cause it to
>>relinquish control of the body and let it just lie there, or is this
>>some sort of specific mechanism to deal with "stress"?  If it is the
>>first (i.e., the brain is really injured by such a shock, and is
>>unable to produce behaviors such as running away, until it recovers),
>>what exactly is it that's wrong? I can't easily imagine any physical

A bird flies into a windowpane and is stunned.  It falls to the ground
quivering, but, presuming it wasn't a 10th story window, in a minute or
two it's back to hopping around and takes flight soon after.  The fact of
the rapid recovery from stunning is more interesting to me than the
phenomenon of the stunning itself.  Of course this varies with the degree
of damage -- some boxers are up before the standing 8-count, others wake
up in the training room or worse.

The army (or some branch of the US military) had a research program for a
while to study the issue of acute head trauma and recovery.  It involved
hitting pigs in the head with a special device that controlled the force
of the blow.  The pigs naturally had to be conscious when the procedure
started -- how are you going to learn these things with anesthetized pigs?

The study aroused considerable opposition when it came to light, and it
may have been shut down.  Does anybody know if this study is still or
again underway, or anything else about it?

The rationale for the study, I believe, was that human head trauma cases
were not informative enough because there was no information about the
force of the blow, different cases had different forces and sites of
blows, and it was often a matter of an hour or so after the blow that the
victims arrived in emergency rooms, and after that the patients were
unavailable for a while as the trauma team had first crack (so to speak).

If any information came out of this study it could bear on the question at
hand.  It's a gruesome method but as long as it was done (if it ever got
off the ground) it seems the data should be available because it's
probably not going to be done again.  My opinion, of course.  Anybody out
there think data from ethically questionable experiments should be suppressed?

Doug Fitts
dfitts at u.washington.edu



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