From: jbates@encore.com (John W. Bates)
Subject: Re: Spoken Like a True ProLifer
Organization: Encore Computer Corporation
Date: Tue, 12 Jan 1993 18:28:14 GMT
	<1993Jan11.065635.16749@organpipe.uug.arizona.edu>
	<1993Jan12.040001.6011@mnemosyne.cs.du.edu>


In article <1993Jan12.040001.6011@mnemosyne.cs.du.edu> mcochran@nyx.cs.du.edu (Mark A. Cochran) writes:
>In article <1993Jan11.065635.16749@organpipe.uug.arizona.edu> sfm@manduca.neurobio.arizona.edu (Stephen Matheson) writes:

>>>>> Given that myelination is necessary for proper
>>>>> conduction of impulses in the brain
>>
>>>>Just how "given" is this?  Before myelination, aren't most fibers
>>>>nevertheless conducting impulses, albeit much more slowly than after
>>>>myelination?  I'm going to go check this, but I'm rather sure at this
>>>>point that myelination speeds conduction rather than making it possible
>>>>(that's the job of ion channels).  Pre-myelinated fibers, in at least
>>>>some cases, are just as competent to have excitable membranes.

This is true. The question is, just how "tuned" are our thought processes?
How much do they depend upon internal synchronization? I don't believe
that the answer to that is known. Certainly processes exist in less
complex systems which do require a great degree of synchronization:
take, for example, the escape reflex of a squid. How comparable that
is to human thought, I couldn't tell you.

>>> Premylinated fibers do conduct some impulses, certainly. They are, as
>>> you pointed out, conducted at a much slower rate. They are also (if I
>>> remember my neuro) subject to transmission failure at a fairly high
>>> rate. 
>>> As an analogy, consider the conversation we are having. If every third
>>> line were dropped, or if random words were deleted, it would no longer
>>> bear any resemblance to rationality.
>>> How could we have rational thought with the same random loss of
>>> impulses?
>>
>>I suppose if we built in enough redundancy, we might be able to pull
>>it off.
>>
>Redundancy does not help if the signal is *lost*, although it would
>help if *multiple* signals were being sent, and only *some* were being
>lost. Does your study or neurology indicate tha tthe brain sends out
>multiple copies of each signal? I admit I don't know one way or the
>other.

Pardon me for butting in here, but I have a small amount of relevant 
experience, and this is a fascinating conversation.

Redundancy in the brain is not the same as redundancy in a computer,
or even in most human engineered systems. Whereas humans tend to build
redundancy in by having multiple copies or backups, the brain's 
reduncancy comes about as a result of its distributed nature. A great
deal of signal error or loss can be endured before the output, such as 
it is, is significantly affected. Losing signal might be equivalent to
say, losing a pixel from each letter in this post. 

[deletions]

>Further, we know that in early pregnancy, these same
>roots must be myelinated before movement (other then twitches, which
>occur as much from random excitability of the muscle tissue as
>anything) takes  place i nthe fetus. Considering this, and considering
>how much more complex the electrical activity of thought must be, do
>you not think it is resonable to say that thought is unlikely to be
>present?

I consider that a reasonable assumption.

[deletions]

>>Can you prove that consciousness exists?
>>
>To my own satisfaction, yes. But if "personhood" is based almost
>wholey on subjective data and personal philosophy, isn't
>"conciousness" as well?
>If we define conciousness as the ability to respond intentionally to
>oputside stimulation, then I think we can show it's existance. The
>"intentionally" qualifier rules out the reflex motions o a fetus is
>capable of, but also puts neonates on shakey ground.

So? I don't see why any definition of personhood based on consciousness
necessarily includes neonates. If evidence points away from it, why bend
over backwards to fit them in? Science is really no basis for morals, and
often makes a poor basis for laws. (Except when "ye canna change the laws
of physics, Captain.")

>>On a different tack, if I show that the developing brain of a
>>6-week-old fetus is busily firing impulses (long before "brainwaves"
>>can be detected by an EEG), then I can make a case for the
>>POSSIBILITY of mental function.  Of course, I can't prove it
>>exists, but this makes the situation quite different than, say,
>>the contention that Elvis is alive on Mars.
>>
>Of course he's not, or I couldn't speak for his ghost. ;-)
>The mass of tissue in a 6 week embryo (not fetus, not until week 9, as
>you pointed out to another poster... ) which may eventually become a
>brain may well be firing impulses. But does it qualify as "mental
>function" (which I take to mean some relation (cousin, perhaps) to
>intelligence)? Motor neurons fire at random, even in adults (you've
>seen peopel twitch), so it can be assumed (or proven, possibly) that
>others do as well. But for it to qualify as some omen of developing
>intelligence, it would need to be (to me anyway) organized. 
>I don't put much faith in the EEG, honestly. I've a friend in the
>neurophysiology area who has been known to say "I can get an EEG of 3
>cells in a petri dish." It's a far cry from the brainwaves seen in
>adults, or even neonates, but it is an EEG...

Here's where it gets interesting. I recently saw a paper which was an
analysis of the activity in a fetal cat's geniculo-striate pathway and
the lateral geniculate nucleus. What was assumed to be random activity
now seems not to be, but rather a hard-coded sort of "training exercise."
Even when the cat's eyes are closed (and in fact, have not ever been
opened) this training is preparing the visual system for eventual use.

Which raises the question: is the activity in a fetus' brain, which 
might be mistaken for random thought processes, actually a training
exercise for eventual thought and consciousness? If so, when does it
cease to be training? I would tend to lean towards the point at which
external stimuli begin affecting the patterns. 

Unfortunately, I don't have the references for the paper here, and
I did not read it thoroughly when I had it. I'll dig it out tonight
and see what it says. It's entirely possible that I read too much
into their conclusions.

[deletions]

>>> I don't think there is going to be a good answer, not for everybody.
>>> That's my main reason for advocating leaving the choice to the
>>> pregnant woman. I don't think the potential of the fetus can outweigh
>>> the reality of the woman.
>>
>>I am resigned to the reality of choice being left to women and
>>abortion providers.  That's why I think it's worthwhile to 
>>discuss the moral issue of abortion (in this case by discussing
>>scientific aspects of the personhood question).  While I agree
>>that the fetus mustn't outweigh the mother, I reject the notion
>>that the conflict is between "potential" and "reality" and assert
>>instead that it is between 2 different realities.
>>
>I don't think this is what you mean, but your first line above makes
>it sound as if the woman approaching the abortion provider has not
>already decided what she wants. In cases I've seen, the woman has
>approached her OB, or GP, who either performs the abortion or refers
>her to a suitable provider (especially in late term or other high risk
>cases). The only cases I know of in which a physician has encouraged a
>woman to abort has been cases of severe abnormality. And even in these
>cases, the choice always lies with the woman.
>I can agree with you on the different realities idea.
>We both see pre-birth "personhood" as a possiblity. I think the main
>point of difference we have is that you choose to make any error (wrt
>this possibility) in favor of the fetus (subject to the balancing you
>mention above), while I prefer to make that possible error on the side
>of the woman carrying the fetus.

As I said above, I don't believe that science is necessarily a perfect
guide to morality or legislation. If it can be incontrovertibly shown
that "personhood" does not begin until some specific point, the conflict
will remain. Just look at the number of people who will argue with all
of their convictions that abortion is wrong, from fertilization onward.
Personhood is an interesting philosophical and scientific inquiry, but
I don't believe that it can lead to a resolution of the abortion debate.

>>> BTW Steve, you forgot to include a gratuitous insult... Are you
>>> slipping up? ;)
>>
>>Slipping up?  No.  Cracking up?  Why yes, you pathetic pile
>>of primordial soup.  Was that gratuitous?  I'd better look it
>>up...
>>
>HA! You admit you don't have the dictionary memorized? What sort of
>t.a poster are you? Did your last EEG get reverse polarization and fry
>that miserable excuse for a brain of yours??

Can somebody please insult me? Nobody ever insults me... Do I have to
insult someone else first? (Actually, I think I insulted Chaney or Hall
sometime back, but I didn't get anything back. Oh, and I got Nyikos
to post his SAT scores, but he forgot who I was. He did call me a "bozo",
but that hardly counts. He didn't even use my name.)

John

p.s. I don't have a whole lot of experience in neuroscience. My background is
from that hazy field of "cognitive neuroscience," which means I get to wave
my hands around a lot.