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Humans use 10% of brain... true?

Martin Knopman mknopman at worldnet.att.net
Thu Aug 26 00:16:32 EST 1999

Jaimie Polson wrote in message ...
>In <7q2135$j35$1 at bgtnsc02.worldnet.att.net> "Martin Knopman"
<mknopman at worldnet.att.net> writes:
>>henrik at unge-forskere.no wrote in message <7pun9k$9bs$1 at nnrp1.deja.com>...
>>>Is the common (pseudo-scientific) myth that humans only use 10% of
>>>their brain true?
>>I don't even know what this question means!  You have some notion of 100%
>>utilization of the brain?  Can anyone cite a study, or conjecture, that
>>computational capacity of the normal human brain (outside of newly created
>>and acquired linguistic devices?) is x.  And has anyone ever even come up
>>with an estimate for the average (?) computational work done by some
>>brain, in some average situation, after an average amount of sleep,
>>some average thought, within an average emotional environment, ... I think
>>that it's even hard to determine %100 utilization of many simple
>>machines - different contexts yield different answers, not to mention the
>>unknown productive contexts.
>Um, the brain does a lot more than "compute", think thoughts etc.

Um, I think that, um, we have different definitions of computation ... but
how is it that you KNOW that the brain does a lot more than compute? What
are these other qualities?  If you are going to address a question that
speaks about a specific proportion of utilization of some system then you
must have some form of measurement on which you are basing your assessment.

>And most of
>the brain's functions work pretty well, even if you haven't had an average
>amount of sleep.

Yes, my thinking is always clear after 30 hours without sleep.  I always
think best when I'm in a pressure situation, or when I'm depressed, or when
I'm scared,...  Come on.

By the way, why did you say "...the brain's functions..." which has a very
computational ring to it?!?  If the brain is performing, by your account,
important [my inference] non-computational tasks, then they are not
functions ... unless you have some deeper insight into the Church/Turing
Thesis than anyone else.

>I think the question is pretty simple.  You have 100 neurons
>in your brain and you use 100 of them (for what ever function).
>  QED 100%
>usage.   You use 10 of them, then 10% usage.

Again, we have a basic problem here with what you term "use".  If I spill my
brain out onto the table and feed 100 neurons to my cat, then they are being
"used" ... but that is not what you mean, is it.  You have very specific
types of uses in mind, so maybe you should be a little more specific.  You
do not even touch on the subject of efficiency.  Raw neuronal usage is a
measure that is of no interest, at all.  Again, you felt the need to include
"(for whatever function)" to which my above comment applies.

You also seem to be making the assumption, here, that all neurons could be
"used" (in whatever way you want) constantly (you gave no time frame for
usage, so I assume it was 'at all times').  If not, then you have to
determine the mean temporal utilization of a neuron, just to get a standard
by which you determine full usage.  Look, by your definition no human has
ever worked "100%", and you would be led to say that every human workforce
operates at less than 50% of capacity. That is clearly silly.  Sleep is
something that has to be taken into account when woking with humans, and we
do not know what the maximum load is that a neuron can take and still
function properly.

There are also such things as redundancy, error correction, etc. to which
many neurons would have to be devoted.  These neurons would not operate 100%
of the time, even though the system could be functioning perfectly.
Maintainence is part of any complex system, and the cost of maintainance
makes determinations of perfect utility extremely tough to nail down.  Now,
to address a system as complex as the human brain, where we know very little
it, makes the determination close to impossible.

Your simple definition of utilization is, in my mind, unacceptable, for it
says nothing.

>  The question is do some neurons
>just sit around and never do anything.  The answer.  I dunno.

Of course you don't know.  No one knows, which is why the original question
made no sense.

> I suppose
>this kind of statement comes from knowledge of various insults to the
>brain - small stroks, brain surgey, injury etc that do not appear to effect
>our functioning.

I do not agree with that statement.  I don't know of anyone who claims that
a small stroke has no effect on brain function.  It is one thing for someone
to appear normal after a stroke, but quite another to claim that their brain
function has not changed.  As I mentioned above about error correction and
such, any robust complex system must have certain redundancies built into
it, but that does not mean that those redundant functional structures could
just be utilized at any time.

>And also that it is well known that the number of
>neurons in our brain decreases continuously over our adult life.  So
>therefore, we only seem to need a proportion of our neurons to function
>properly (although I don't know where the 10% comes from).

How can you say this?  Give me one example of a great piece of work done by
someone over 50.  There are examples, to be sure, but the fact is that the
most creative years of life are before 35.  Something certainly changes as
we age, and I think that your level of "function properly" is too minimal to
really discuss.  When one is talking about utilization, in this context,
s/he is referring to operating at maximal capacity, not at minimal

>  But the, I
>suspect this comes from redundancy in our brains, rather than simply
>some neurons are not ever active.

Yes, I addressed this above.  But I am perplexed that you would even
consider that "some neurons are not ever active".  We were really talking
levels of activity at given times ... not at all times.

><original poster>
>>>How is this coherent with evolution theory (the extinction of useless
>I don't think this is a good definition of how evolution works.  Species/
>lines prosper over others when they have some advantage.

I hate to break it to you, but there is also a lot of luck in evolution.
There are far too many cases of disadvantaged lines continuing on by luck.
Evolution is not "run from above".  It is a local system, that falls prey to
the same problems as any other system.

>But if something
>is neither an advantage nor disadvantage, then it won't make a difference
>to that specie's survival, so there will be no reason for that feature to
>be lost.

........... reason is something that is assigned to evolutionary events
after the fact.


Martin Knopman

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