From: mcochran@nyx.cs.du.edu (Mark A. Cochran)
Subject: Re: Myelin (Was Re: Spoken Like a True ProLifer)
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Organization: None worth mentioning.
Date: Fri, 22 Jan 93 03:50:27 GMT

In article <1993Jan21.034431.24481@organpipe.uug.arizona.edu> sfm@manduca.neurobio.arizona.edu (Stephen Matheson) writes:
>From article <1993Jan20.062913.13725@mnemosyne.cs.du.edu>,
>by mcochran@nyx.cs.du.edu (Mark A. Cochran):
>
>Odd number of >'s  = Mark Cochran
>Even number of >'s = Steve Matheson
>
>[deletia]
>[following refers to a scientific article on the ramifications
>of delaying myelination of the chick spinal cord; mostly deals
>with regeneration]
>
>>>I read the abstract but didn't copy the article; I'll get it and post
>>>anything interesting and/or relevant.
>
>> I'm looking forward to it, it sounds *extremely* interesting.
>
>Got it.  Will read it tonight, and post under a new title, perhaps.
>
>[huge deletion of discussion of synapses in development]
>
>>>Yeah, the tumult over fetal tissue research is a little baffling to me.
>>>I believe it to be a separate issue from that of abortion, although
>>>that's because I assume that we all agree that conceiving for the
>>>purpose of aborting to provide tissue is morally unthinkable.  
>
>> Of course it is. And nobody has ever shown that anybody has ever done
>> this. It's just something the more rabid pro-forcers use to try and
>> scare people. There's more tissue available from regular abortions then
>> could possibly be used.
>
>>>In the absence of such intent, my proposal that we study dead e/f
>>>tissue is no different from a proposal to study the brains of
>>>deceased Alzheimer's patients.  But that's another thread.
>
>> It would be an interesting one too, but lets save it for when this one
>> dies out. I don't think I could handle another thread like this one
>> right now. :)
>
>But Mark, you make it look so easy...
>
I think I said once before. Intelligent dicourse begets intelligent
discourse. Idiocy begets flamage. As I recall, it was you actually
replying in a rational manner to one of my flames of a rabid
FetalIdolotator that got this started.

>[deleted discussion of nonsynaptic neural communication]
>
>>>>>> (I think we're going back into the quantitative
>>>>>> vs qualitative debate again...) I don't have any doubt that the brain
>>>>>> of a 38 week fetus has the necessary hardware to perform the mechanics
>>>>>> of thought, but does it have the experiential basis (the software?)
>>>>>> for the task. 
>>>>>> Can thought occur without both the hardware (neural development) and
>>>>>> software (experience/data)?
>
>>>>>How else does one acquire the needed "experience/data"?  More importantly,
>>>>>why is it so often assumed that the embryo/fetus is so hopelessly
>>>>>deprived of "experience/data"?  In this area you are our recognized
>>>>>expert, Mark.  There can be no debate that the e/f environment is
>>>>>fundamentally different than that of a neonate.  It seems obvious that
>>>>>the e/f environment is lacking in certain types of stimulation.  But
>>>>>if "experience/data" are really that important, I see no reason to
>>>>>claim that the e/f lacks either.  Talk to me, Mark.  This could become
>>>>>a really interesting branch off this bloated thread of ours.
>
>>>> The stimuli the fetus receives is also of both a quantitative and
>>>> qualitative difference. There can be very little tactile stimulus, due
>>>> to the cushioning of the e/f environment.
>
>>>Very little *externally applied* tactile stimulus.  But as long as
>>>there's plenty to touch in the uterus (and there is -- that pesky
>>>umbilical cord seemed to be everywhere in our sonograms), there
>>>must be plenty of tactile stimulation.  Correct?
>
>> That's whya I said very little. The cord and uterine walls are there,
>> but provide only a very limited and very unchanging sensation. I mean,
>> there's only so much information you can glean from touching a
>> basically smooth cord, and basically smooth walls, and a basically
>> smooth placenta. I'm not downplaying tactile sensation, I just don't
>> think it provides much variety to train the brain.
>
>>>> Obviously, visual stimulus
>>>> is pretty much out of the question. Olfactory as well. Rather
>>>> difficult to smell when you don't have any air. Taste may receive a
>>>> minimal stimulous from the aminotic fluid, the taste of which (we may
>>>> assume) changes a little during the pregnancy, due to such mundane
>>>> things as the fetal kidneys beginning to function.
>>>> So we are left with audio stimulous as being by far the most common.
>
>>>Yes, but we probably should give at least passing mention to
>>>proprioception: the moving e/f will provide ample stimulation of
>>>brain areas concerned with detecting the movement of muscles,
>>>tendons, joints, etc.
>
>> Granted, although given how little a toddler seems to know about where
>> his feet are, I'm not sure it's true. (This is a joke, since my
>> toddler is always tripping over her own feet)
>
>Our 2-month-old just discovered his.  Visually, that is.  I must 
>agree with you: the evidence that youngsters *use* proprioceptive
>information is not very strong.  But there are too many days on
>which I have the same difficulty...
>
>>>> We know (or at least we think we know) that the way a neonate
>>>> recognises it's mother is by sound. Hold a newborn between the mother and
>>>> another woman. No preference will be shown until voices are used. Even
>>>> a 1 day old infant can turn it's head towards it's mothers voice.
>>>> There have even bee na few studies which made a (fairly weak)
>>>> connection between fetal movement and the mothers musical listening
>>>> habits.
>>>> One thing to note is that this ability to turn the head in response
>>>> to mothers voice seems to be absent in preemies of the 20-26 week
>>>> variety. I'm open to debate on whether this is due to the neonate not
>>>> recognising it's mothers voice, or simply lacking the energy to turn
>>>> it's head, considering how hard it is working just to stay alive.
>
>>>It would be interesting to test these hypotheses, but it must be
>>>hard (in more ways than one) to study preemies.
>
>In any case, I'm guessing that the fetus is able to respond to
>auditory stimuli much earlier than 20-26 weeks.
>
I'm sure that a fetus can pick up auditory data prior to 20-26 weeks,
but I'm not at all sure they can react to it. I've seen a couple
studies which tried to link fetal movements with what music the mother
was listening to at the time. They were *really* poorly done, and I'm
afraid I don't give much credance to them. Even after birth, about the
only reaction we see from auditory input is a turning towards the
mothers voice. While 'my baby is dancing' is really cute when momma is
listening to her favorite station, I don't think it's really
happening.

>[deleted lesson on neonatal stimulation and colic]
>
>>>> I see this in utero stimulation as being part of the patterning, or
>>>> training needed by the brain for it to program itself to perform what
>>>> we eventually consider thought. 
>
>>>So, would you say that the brain is acquiring software at this point?
>>>I would say the brain is *using* it.
>
>> I would say it is using some *very* rudimentary forms, and programming
>> new, more complex routines.
>
>Sigh.  Is this all the disagreement we can muster, Mark?
>
I'm afraid so. Maybe we need an injection of rabid fundamentalism?
*NOT*

>>>>>[Deleted discussion of areas of nervous system that function sans
>>>>>myelin.]
>
>>>>>>>My contention remains: large segments of the nervous system function
>>>>>>>beautifully without myelin.  Myelin has a very specific purpose: it
>>>>>>>allows for fast conduction of impulses.  It must not be indispensible
>>>>>>>for function, because it is anything but ubiquitous.  While it is
>>>>>>>reasonable to guess that speedy conduction would be advantageous
>>>>>>>to a complex network, it seems reasonable to assume that one can
>>>>>>>design a network without it.
>
>>>>>> Kind of like trying to build a hypercube out of a bunch of C=64's? I'm
>>>>>> sure it can be done, but would it actually be capable of performing
>>>>>> any resonable work?
>
>>>>>Huh?  Can you provide some hypercube and C=64 references? :-)
>>>>>Are they available on request?
>
>>>> A hypercube (as I understand it, but it's not my field at all) is a
>>>> bunch of cross-linked multi-processor computers that tries to simulate
>>>> the neural system by multiple cross-links. The C=64 is the ancient
>>>> Commodore 64 that people have always laughed about.
>>>> It would be interesting (funny even) to see what would happen if
>>>> Commodore got hte idea to try this for real. :)
>
>>>Wow.  Mark is a mrpmsysp UGR futrvits (Mark's occupation has been
>>>encrypted at his request; decoder available from T.S.A.K.C. BBS)
>>>*and* a neural network guru.  That's amazing.
>
>> Huh UH! No Way! See right up there where I specifically deny any
>> expertise in this area? I've read a litle bit, and talked to people,
>> but no *way* are you goin to get me to play neural network sysadmin
>> here. ;)
>
>Very well.  You're the one who brought it up.  I wonder if John Bates
>can get enough free time to comment on the applicability of your
>analogy.
>
I hope so. I don't think you have to be an expert on both sides of the
analogy. It's enough if you are at least semi-coherant when talking
about one side of it. ;)

>>>>>I don't see why an unmyelinated network would be incapable of
>>>>>performing any reasonable work.  I can imagine that it wouldn't
>>>>>perform as well as the faster network.  I can also imagine that
>>>>>the growing size might make the myelination important (or even
>>>>>necessary) and that the very small beginning network isn't
>>>>>myelinated because it doesn't need to be.
>
>>>> The resonable work in question, though, is thought. Just as you can't
>>>> use a 4 bit 16K RAM computer as an effective file server, I don't see
>>>> how you cna use the similarly limited abilities ofthe pre-myelinated
>>>> neural system as a 'thought server'.
>
>>>I'm reserving my judgment on the matter for a time when we know more
>>>about all the issues involved.  The hypomyelinated mice discussed
>>>later in the post may be our best window into this issue.  In the
>>>meantime, it must be obvious to everyone reading this thread
>>>(all 3 of us :-) that neither of us has any clue about whether
>>>myelin is necessary or not.  I think that there is at least a
>>>fair amount of information on the biological side that suggests
>>>that myelin is not as central as some claim.  On the other hand,
>>>your arguments about the presumed complexity of the network are
>>>certainly thought-provoking (there's that smell again...myelin
>>>burning or something).
>
>> Actually, from comments others have made, I think there are a few
>> others reading the thread, if not actually posting to it.
>
>So I hear.  I wonder how many are neural networkers or myelin
>experts or EEG specialists who go to their coworkers afterward
>and say, "Hey folks, you won't believe the hilarious hogwash I
>just read on the Internet..."  That's why I like to hide behind
>references.
>
I'd hope if we were that far off base, they'd join the conversation...
It got John to join in, after all. :)

>[deleted commentary on my friend Peter and his natatory skills]
>
>> I guess we're basically stuck back at the 'this is interesting, but
>> how the *hell* can we prove it' stage?
>> It's still fun. :)
>
>And educational, at least for me. :-)
>
It's making me dig into neuro stuff I don't normally use too. :) I
wonder if it's made anybody besides us really think though?

>>>> Obviously, the closer to the nominal delivery date we get, the less
>>>> difficult it becoems to imagine the thought server functioning.
>
>>>This is another problem with the myelin theory.  Myelination is
>>>a late postnatal event in many brain areas.  Dr. Holtsinger
>>>posted some excerpts from a putatively credible source on the
>>>subject (a month or so ago I think...).
>
>> No argument there. Myelination continues for years after birth. So
>> maybe the real issue is not 'are fetuses sentient' but rather 'are
>> children sentient'... (Note to the terminally dull. This is not meant
>> to be taken seriously, nor is it to condon infanticide. jeez, get a
>> life already.)
>
>>>(No, I'm not confused.  I thought I'd refer to Doug as "Dr."
>>>just to be cute.)
>
>> Hmmmmmm do you suppose DODie is really an abortionist? ;)
>
>>>If myelin is necessary to get the server up, it seems that the
>>>"nominal delivery date" is far less relevant than the amount
>>>of myelin in the relevant parts of the network.
>
>> Perhaps, but it would seem logical for nature to ensure a minimally
>> functioning network 'online' before scheduling delivery (Dr. Giggles
>> mail system being the exception that proves the rule).
>
>Nature... logic... these are dangerous water, Mark.
>
Now Now Steve.. Nature does do some extremly sensible things. Consider
something that happens with a 28-32 week fetus. The lungs start to
rapidly develop, producing huge numbers of typeI & II alveolar
epithilial cells, so as to increase surfactant production to a point
which makes survival possible (from the point of being able to breath,
at least).
If a woman goes into premature labor, and delivery can be stalled for
just a day or two, the fetus has a much better chance of survival the
nif it is delivered immediately. The premature labor triggers a
*massive* upsurge in surfactant production, and forces the lungs to
develop faster then normal. Withoutthat day or two's delay (three
cheers for yutopar) the fetuses odds are drastically lowered.

>>[Discussion of muscular/neurological function in fetuses deleted]
>
>>>>>Hmm.  Yes, I'll look this up, too.  Sounds like a risky generalization,
>>>>>but we'll see.  I'm just responding to the first of 17 pages of t.a
>>>>>posts, so perhaps you've already posted some more info.
>
>>>> I still haven't found the citation (this was *not* a good day for
>>>> library time), but I'm not sure it's that risky a generalization. What
>>>> was being said, it seems to me, is that the closer the fetus gets to
>>>> birth, the more 'normal' the responses of the neuromuscular system.
>>>> That seems resonable. It's important to note that this was a study of
>>>> early fetal movement. If the premise was applied to late term fetuses,
>>>> I'm sure it would be both risky and probably incorrect.
>
>>>I'll wait to see the source.  My understanding of neuromuscular
>>>development is leading me to doubt the assertion that the motor
>>>fibers are all that quiet, but I'm not willing to come out with
>>>an outright challenge just yet.
>
>> I found it, and I should have re-read it before I posted. They did
>> find evidence that in the very early stages, muscles twitched without
>> neural discharge, but did not reach a conclusion about the ratio of
>> neuron stimulated contractions to random twitches. Mea Culpa.
>
>My guess is that nerve-evoked muscle twitching is present almost
>immediately upon innervation.
>
It is, along with self-induced twitching. I remembered the
self-inducedpart and forgot the rest of their conclusions.

>> [Mice story deleted]
>
>>>>>Translation: the brains of mice seem to be able to deal unexpectedly
>>>>>well with the loss of myelin.  This is not demyelination: the mutants
>>>>>were never able to make normal myelin.
>
>>>> So we're making progress on finding a no-myelin brain. Excellent. :)
>>>> I wonder how well this compensation could caryyy over to human
>>>> studies? I'm sure it's too early to have any studies on humans yet,
>>>> but we can dream...
>
>>>It may explain some MS observations.
>
>> Again, it's out of my field, but isn't MS a combination of
>> demyelination and ingrowth of non-neural matter in the neural
>> pathways?
>
>I think the demyelination is the primary pathological event.  Glial
>growth could be reasonably assumed to be secondary.
>
It is considered primarily a demyelinating disease, yes, butthe
overgrowths are significant, it seems. Doesn't have much to do with
abortion, but it's interesting. :)

--
                  Mark Cochran          merlin@eddie.ee.vt.edu
These are the views of my employer, your employer, your government, the
Church of your choice, and the Ghost of Elvis. So there.
Member, T.S.A.K.C.
Newsgroups: talk.abortion,alt.flame