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Article 6387 of comp.ai.philosophy:
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>From: long@next1.acme.ucf.edu (Richard Long)
Newsgroups: comp.ai.philosophy
Subject: Re: Intelligence without a brain? Just the facts.
Message-ID: <1992Jun29.155614.21541@cs.ucf.edu>
Date: 29 Jun 92 15:56:14 GMT
References: <BILL.92Jun26113658@cortex.nsma.arizona.edu>
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In article <BILL.92Jun26113658@cortex.nsma.arizona.edu>  
bill@nsma.arizona.edu (Bill Skaggs) writes:
> justin.bbs@cybernet.cse.fau.edu writes:
> 
>    In Michale Talbott's BEYOND THE QUANTUM he cites cases of individuals  
who 
>    are born effectively without a brain, only a thin membrane  
essentially 
>    surrounding the area where the brain should be.
> 
> Over the past couple of years I've heard this story a dozen times.  It
> seems to have become an urban myth, along the lines of the "thousand
> monkey" story, the "you lose a thousand brain cells every day of your
> life" story, and the "you only use ten percent of the capacity of your
> brain" story.
> 
> The fact it is based on is that there are people with hydrocephaly who
> have normal intelligence.
(accurate description of hydrocephalus deleted.)

> The thing is that the "thin layer" is actually quite broad, and may be
> comparable in total volume to a normal brain.  Suppose, for example,
> the normal brain were a sphere five inches in diameter.  If this were
> blown up to a sphere ten inches in diameter, the original brain would
> have the same volume as a spherical shell less than a quarter inch
> thick.  (Work it out!)
This seems plausible, and indeed, Marvin Minsky pointed this out a few  
months ago when there was similar thread going.  However, in the PBS  
special _The Brain_ shown about 1984 or so, Dr. John Lorber of the  
Children's Hospital at Sheffield University, Scotland showed us PET as  
well as CAT scans of these brains, revealing very little activation (in  
one girl, who was a chemistry major at Sheffield university, there seemed  
to be activity in the occipital lobe or visual cortex, and two small  
active spots in the left parietal lobe and right prefrontal lobe only.   
Her head did not seem to be that large compared to normal, and she had a  
shunt operation as a child, but the CAT showed only about 10-25% cortex  
remaining.  It is possible that the PET results may be due to the thinness  
of the cortex, and not an accurate reflection of cortical activity, but  
some analysis would be required to work that out for sure. BTW, I've tried  
to track the particular episode down now for a year to no avail.  Anyone  
know?)  Anthony Smith in his book _The Mind_ (1984, pp228-33) also writes  
of Lorber's cases, and I'll quote some of it:
   "So what are they using as a brain?  The answer, briefly, is what they  
have by way of a brain.  Normal infants have a cerebral thickness of 4.5-5  
centimeters (1.8 inches) but those with gross hydrocephalus have this  
thickness reduced to 0.5 centimetre (0.2 inch), or even less. ...
The fact of the skull being enlarged, caused in the main before treatment  
of the hydrocephalus, partly explains the brain's thinness: it has been  
stretched thin.  An extra centimeter added to a normal head circumference  
of sixty centimetres increases the volume of a 1-mm layer lying beneath  
the skull by 3.5 percent.  The increment is considerable, and  
hydrocephalics can have head circumferences ten centimetres above normal,  
but the quantity of brain matter is still minute relative to that in  
normal heads.  As Lorber once pointed out, 'You can put a needle in these  
babies' heads, and you can roam around with your needle to encounter no  
resistance whatsoever.' Nevertheless such infants can thrive, provided the  
excessive ventricular pressure has been shunted to normal."

> 
> To my knowledge, there exists no report of a patient with normal
> intelligence being brought to autopsy and his/her brain tissue being
> found to have dramatically less volume than normal.  (Brain scans,
> such as MRI, cannot be trusted because their interpretation is based
> on the fluid content of the tissue, which is bound to be abnormal in a
> hydrocephalic patient.)
> 
> 	-- Bill
> 
> (Note 1:  There is another condition, called "anencephaly", in which
> children really are born essentially without a brain, but such people
> are invariably profoundly retarded -- basically lacking all but the
> most primitive reflexes.)
     I have in front of me one of Lorber's original papers,  
"Hydranencephaly with Normal Development", _Developmental Medicine and  
Child Neurology_ (1965, 7, 628-633).  He begins: "Hydranencephaly is a  
well recognized congenital malformation of the central nervous system in  
which the cerebral hemispheres are altogether missing [as opposed to  
Hydrocephalus, where they are squeezed and stretched thin].  This may be  
because they have not developed in embryonic life, or have been destroyed  
by vascular occlusions, or have been destroyed as a result of infection,  
drugs or mechanical attempts at abortion."  Here is his description of one  
case.
     "Grant.  Born June 13, 1963.  Birth weight 7 lb.  First son of an  
unmarried mother.  Uneventful pregnancy and labour.  Referred on account  
of rapidly enlarging head at 10 weeks of age.
     "At this stage he was well and he reached the usual milestones at the  
right time.  He had no abnormal neurological signs but his head  
circumference was 17.5 in.  (42.5 cm).  His anterior fontanelle was very  
wide but not under great tension.  A right sided tap at his anterior  
fontanelle produced clear normal cerebrospinal fluid at a depth of only a  
few centimetres from the skin.  The pressure was 180 mm. of water.  After  
injection of air, a radiograph showed no evidence of cerebral cortex--the  
air collecting immediately below the inner table of the skull and moving  
freely in all directions.  No brain was encountered during needling the  
skull on this occasion.  But for the absence of symptoms and the fact that  
the CFS was fully normal at this stage, this could have been a case of  
gross subdural effusion.  The alternatives were extreme hydrocephalus of  
hydranencephaly.  A Spitz-Holter shunt was performed on September 9, 1963  
and this large cavity was drained into the right cardiac auricle, but  
technical difficulties were encountered and his head continued to grow at  
an abnormal rate.
     "His head circumference at 17 weeks of age reached 19.25 in. (50.0  
cm.).  Nevertheless his shunt was re-explored and the upper catheter was  
found to be blocked and was replaced.
     "In spite of this his head continued to grow too rapidly and at 12  
months of age his head circumference reached 23 in. (59.0 cm.).  His  
physical and mental development progressed normally.  he appeared to have  
good eye-sight and hearing, was able to stand unsupported and walked with  
one hand held; attempted to feed himself with a spoon; was playing little  
social games and was able to say two to three words with meaning.  he had  
good finger-thumb apposition.  He had no abnormal neurological signs.  At  
this stage his development was recorded on a cine film.
     "He was readmitted for lumbar air encephalography and for injection  
of air if necessary, via the still widely open fontanelle.  Under general  
anaesthesia his lumbar cerebrospinal fluid pressure was over 400 mm. of  
water.  40 ml. of air were injected.  This outlined the fourth ventricle,  
but no air went into the aqueduct of Sylvius or beyond.  After this film  
was obtained, a fontanelle tap was performed.  the fluid was under a  
pressure of 450 mm. and was crystal clear.  100 ml. of CSF were replaced  
by 70 ml. of air.  Radiographs taken confirmed the apparent absence of  
brain above the tentorium.  Nevertheless, an EEG showed evidence of some  
electrical activity.
     "A further revision of the shunt was undertaken on July 20, 1964 and  
for the first time adequate drainage was obtained.  His head circumference  
has not increased since, up to 21 months of age.  His sutures were closed  
and his head no longer transilluminated.  His general physical and mental  
development continued at a normal rate.  
at 21 months of age he was an alert, playful boy, able to say many words,  
liked to look at picture books, pretended to 'read', and named some  
pictures.  he liked playing with toy cars and building toys.  He could  
feed himself with spoon and fork.  he was running about all day, with  
occasional falls.  He was toilet trained during the day but had occasional  
accidents.  Apart form his large head, he had no abnormal signs.
    "The diagnosis of hydranencephaly is beyond dispute in both these  
cases as judged by all the criteria of the condition.  The continued good  
progress of the first patient was so astonishing thought, that repeated  
attempts were made to find evidence of some residual cerebral tissue by  
air studies (to aid further surgical treatment), but none was found up to  
12 months of age.  Since then his shunt has worked so well and he himself  
has been so healthy and normal, that it would have been unjustifiable to  
subject him to further investigation at this stage.  His skull was fully  
ossified and it no longer transilluminated.  It is unlikely, however, that  
the brain should have developed after 12 months of age, when none was  
present before.  nevertheless, there ought to be some cerebrum somewhere,  
as it is impossible to explain his progress otherwise.  At this stage, one  
can go no further and he remains, in this respect, an enigma."

> 
> (Note 2:  I don't think this topic is particularly appropriate to
> comp.ai.philosophy, so I won't follow up on any responses; but I'll be
> happy to correspond by Email.)
     On the contrary, the possible plasticity of the cortex is extremely  
important to comp.ai.philosophy as I'm sure most others will agree.  If  
true, it suggests that the cortex is largely self-organizing rather than  
developmentally pre-determined.  This restricts possible models of the  
brain, and suggests that self-organizing models of AI are worth  
investigating.
     I do find it disturbing that Dr. Lorber seems to be the only source  
of these reports.  Does anyone have any other sources?

--
Richard Long
Institute for Simulation and Training
University of Central Florida
12424 Research Parkway, Suite 300, Orlando, FL 32826
(407)658-5026, FAX: (407)658-5059
long@acme.ucf.edu


