why does brain impact cause unconsciousness?

Douglas Fitts dfitts at carson.u.washington.edu
Sat Sep 18 23:23:04 EST 1993


mlevin at husc8.harvard.edu (Michael Levin) writes:


How about "stunned" instead of "knocked out".  
Be careful of watching too much TV.

Doug


>     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
>damage that can be repaired in the span of time in which people
>commonly regain consciousness (sometimes minutes). Or am I wrong? WHat
>could it be? If, on the other hand, the brain isn't really damaged,
>but has a specific mechanism for doing a blackout when hit, then why
>did this evolve? It seems to me that a more evolutionarily beneficial
>strategy, when hit on the head, would be to run away (or fight) as
>best as one can, given whatever injury really happenned, rather than
>lay there unconscious. This whole thing reminds me of robots in sci-fi
>movies (especially "Terminator"), which when injured, simply keep
>doing whatever they were doing, as best as they can, while they still
>can (as insects seem to, I think), as opposed to dropping unconscious
>from a sub-lethal injury. So, what do people think?  Please email to
>mlevin at husc8.harvard.edu. 

>Mike Levin



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