Xref: utzoo sci.med:4226 sci.bio:923 sci.misc:837
Path: utzoo!mnetor!uunet!seismo!sundc!pitstop!sun!amdcad!ames!ll-xn!mit-eddie!uw-beaver!tektronix!sequent!mntgfx!msellers
From: msellers@mntgfx.mentor.com (Mike Sellers)
Newsgroups: sci.med,sci.bio,sci.misc
Subject: Re: Brain unnecessary?
Message-ID: <1988Feb18.180605.415@mntgfx.mentor.com>
Date: 19 Feb 88 02:05:58 GMT
References: <955@radio.toronto.edu>
Organization: Mentor Graphics Corporation, Beaverton Oregon
Lines: 91

In article <955@radio.toronto.edu>, brian@radio.toronto.edu (Brian Glendenning) writes:
> [...]
> <I realize that there is a large difference between *no* brain cells and a
> <layer of cells less than 1 mm thick.  The article I read was much more recent
> <than the articles I found yesterday, and definitely contended that people can
> <function with no brain cells at all.  It is difficult to say whether this is
> <the result of uncovering subjects without brain tissue, or perhaps might be
> <the result of some journalist getting carried away.  I do know that the source
> <I first saw was one that I trusted, and the article was convincing.  [...]
> 
> Is this right? Does anyone have any information? A bibliography or good recent
> reference would be great, but any information would be appreciated. I am
> skeptical of this "no brain" idea, but could believe the position of another
> respondent who said the research showed that people could live normally with
> something like 10% of normal brain cells. On the other hand, since I'm an
> astronomer with virtually no knowledge of this subject, I may be totally out
> to lunch. What's the scoop?
> -- 
> Brian Glendenning                INTERNET - brian@radio.toronto.edu


  First, a few sources that may help:

Aymlard, G. P., Lazzara, A., Meyer, J. 1978.  Neurological Characteristics
    of a Hydroencephalic Infant.  Developmental Medicine and Child 
    Neurology  20 (2): 211-217

Dobbin, J., Sands. J 1973. Quantitative Growth and Development of the
    Human Brain.  Archives of Disease in Childhood 48:757-767

Fishman, R. A. 1980, Cerebrospinal Fluid in Diseases of the Nervous System.
    Philadelphia: Saunders.

Milhorat, T. H. 1972, Hydrocephalus and the Cerebrospinal Fluid. 
    Baltimore: Williams & Wilkins.

Also many good neurology texts will discuss hydrocephaly at least a little.

I don't agree with most of the claims made in the article you referenced
(and I hate to say it, but an article in Psychology Today carries just a
little more weight than one in Reader's Digest does :-7 ).  People definitely
need brain cells to function.  The examples give are either untrue or 
distortions, I'm sure (for example, the honors math student may have had
trauma-induced, rather than cogenital hydrocephaly, which could have a
more gradual deleterious effect on his/her intelligence and personality than
if his/her brain had developed that way).

To know a little more about situations like this, you have to understand a 
few things about neuroanatomy, and also understand that relatively little
is known about its pathological limits and responses.  The cerebral cortex 
is usually about 2mm thick (with some individual variation), and is scrunched 
and folded so that it fits inside the skull.  Underneath the cortex, which 
consists almost entirely of small (local) neurons and the cell bodies of 
other neurons, is the so-called white matter, which is made up entirely of 
fibers going to and coming from targets in the body.  So it isn't like your 
head is chock full of a mass of brain cells like a big sponge or something; 
most of the cells themselves actually live on the "outside" of the brain, 
with the afferent and efferent fibers taking up the bulk of the middle.  In 
the white matter are the cerebral ventricles, which contain cerebrospinal 
fluid (CSF).  CSF acts as a shock absorber, nutrient fluid, and probably as 
a messenger fluid for hormones, etc.  An excess of this fluid due to blockage, 
or a malfunction in its manufacture or uptake, can cause excessive pressure 
on the cerebrum, often resulting in hydrocephaly.  From what I've read, the 
white matter fibers are both pushed out of the way and/or severed (via 
degenerative stress), so this could definitely have an effect on the cortex
and a person's behavior.  It makes a big difference if this happens to you
as an adult vs. as a child; in young children, the brain is still growing
furiously and will not react well to the excess pressure from the ventricles.
In these cases, the effects of the hydrocephaly are probably the most profound.

Also within the white matter are the basal ganglia, which as a group are much 
like a smaller, evolutionarily older brain within the cerebrum.  These 
structures seem to mediate many complex behaviors, including emotional
responses, walking, writing, some phonation, and other programmatic actions.
I'm not sure how much the basal ganglia would be affected by excessively
large cerebral ventricles, but it is possible they could escape largely
unharmed.  These structures are often ignored by people discussing the
brain, and yet they seem to be responsible for much of the coordination of
our behaviour.  If these remained largely intact while the cortex gradually
degenerated, the most visible effects of the degeneration could be masked.

That's about all I know about hydrocephaly.  Maybe one of the med-student
types could fill us in more on the effects of it on the basal ganglia, etc.
The bottom line, though, is that you definitely need the bulk of your brain
cells to function normally; I'd be very suspicious of someone who says 
otherwise without good documentation.

-- 
Mike Sellers                           ...!tektronix!sequent!mntgfx!msellers
Mentor Graphics Corp., EPAD            msellers@mntgfx.MENTOR.COM
"Never confuse motion with action." -- Ben Franklin