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Neurogenesis - CORRECTION of False Attribution

kenneth Collins kpaulc at earthlink.net
Mon Jan 31 05:05:20 EST 2000


the Attribution in my original post is False. it should've been:

    "The Development  of Maps and  Stripes in the  Brain", by
    Martha  Constantine-Paton  and  Margaret  I.  Law, SCIENTIFIC
    AMERICAN, Volume 247,  Number 6, Dec.  1982, (p. 62),  for an
    introduction to stripes and aspects of their development.

which is referenced in AoK, Ap6, and is in AoK's Bibliography.

and, in the original msg,  i botched the description of the experiment.
Constantine-Paton  and   Law transplanted a 3rd eye into a frog, and its
optic nerve, typically, entered into competition with a the optic nerve from
a 'normal' eye, in one of the frog's optic tecta, yielding stripes. which
vividly demonstrates in favor of activation-dependence because, the 'normal'
tectum receives fibers massively from only one eye, and, hence there are no
'stripes', so there could be no molecular markers involved in this
transplant-induced 'stripe' formation ('cause it's not in the 'normal'
biology).

I =Apologize= to the Constantine-Paton  and   Law for not properly crediting
their work while referring to it.

the Arbib article that i Falsely cited had to do with an 'transplant'
operation in which the topography of the frog's optic nerve/tectum was
reversed... which resulted in the frog's tongue going in just the opposite
direction of a fly that had come into it's visual field... which is
in-topic, because it demonstrates the high degree of plasticity in
reptiles's 'brains'... the reoriented optic fibers just wired themselves up
(backwards, because of the operative manipulations, which, BTW, demonstrates
a lack of specific molecular 'markers' to guide the transplanted fibers, at
least at the 'time' of the operation, and, so, favors activation-dependence
as the mechanism guiding the rewiring after transplantation). i distinctly
recall that this Arbib article was in the Pribram ref cited in the original
msg.

K. P. Collins

kenneth Collins wrote:

> there was an interesting experiment done by one of my former Professors,
> Michael Arbib (i think i read of it in a book, _The Metaphorical Brain_,
> by K. Pribram, but i read that ~25 years ago, and am not certain that my
> recollection is Correct), and which makes-clear some of the
> activation-dependent neural dynamics that i've been discussing,
> in-particular, how the ocular-diminance 'columns' and 'stripes' form.
>
> Arbib transplanted a 3rd optic tectum (=roughly= analogous to primary
> visual 'cortex') into a frog. although it was ab-'normally' displaced,
> this transplanted tectum became innervated from the frog's eyes, and
> showed 'typical' ocular-dominance 'columns' and 'stripes'.
>
> at first, the fact that it did become innervated from the frog's eyes
> does support the view that there is some sort of 'molecular attractant'
> that's involved, else the transplanted tectum would've become innervated
> with respect to some other functionality, say, audition.
>
> but the transplanted tectum is radically-displaced from 'normal', so
> given the fact that it was relatively-well-developed tectal tissue, a
> generalized mechanism, in which any neurons could find their way to the
> tectum, but in which only those neurons whose activation 'fit' the
> neural activation dynamics of tectal tissue are sustained, would wire
> things up 'appropriately' with nothing more than TD E/I-minimization
> doing the 'guiding'.
>
> and, as is discussed in AoK, Ap6, the formation of 'normal' ocular
> dominance 'columns' and 'stripes' follows as a 'normal' TD
> E/I-minimization consequence, because relatively-high TD E/I would occur
> in a completely-mixed neural distribution.
>
> how about orientation 'columns' and 'stripes'?
>
> these also form via TD E/I-minimization.
>
> recall my prior discussions of 'sliding fields' (also see AoK, Ap6 and
> the little QBASIC InfoCalc program.)
>
> it helps to study the InfoCalc program's 2nd Derivative dynamics, but
> the same can be done through some 'doodling' with pencil and paper.
>
> all the orientation 'columns' and 'stripes' are are groupings of
> 'conjunctions' within the 'sliding fields' that are formed, as a result
> of TD E/I-minimization, as the 'sliding fields' do, in fact 'slide over'
> one another.
>
> conceptualizations that attribute more 'meaning' to the orientation
> 'columns' and 'stripes' are just giving way to 'Illusion'.
>
> it all reduces to TD E/I-minimized optimization be-cause TD
> E/I-minimization is what optimizes the neural topology globally,
> allowing each neural dynamic, within a nervous system, to 'understand'
> the neural dynamics that occur everywhere else within nervous systems,
> and unifying 'consciousness'... even in frogs, even in insects, and in a
> just-energy-flowing, non-neural, way, even in bacteria (see the
> discussion of 'bacterial chemotaxis' in AoK (or any introductory Biology
> text)).
>
> this is =not= to say, of course, that an ant's 'consciousness' is
> equivalent to Human Consciousness. it's just to say that what unifies an
> ant's 'consciousness' is the same thing that Unifies Human
> Consciousness, TD E/I-minimization.
>
> K. P. Collins







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