[Neuroscience] Re: Mirror, Mirror .... You Bloody Liar
(by j_hasenkam At yahoo.com.au)
Thu Jan 25 22:14:47 EST 2007
Noted the avatar, read the post, and thought: is this Ken or a clone?
Good to see you're still around. You are the only person so far who has
"seen" the problem. As Bertrand Russell once said, "one of the first
problems in philosophy is to recognise that a problem exists.
Trust you are well,
On Jan 25, 11:51 pm, "Benjamin" <Benja... At verizon.net> wrote:
> <raipane... At gmail.com> wrote in messagenews:1168931407.577719.15720 At v45g2000cwv.googlegroups.com...
> > John H. wrote:
> >> When I look in the mirror right\left is inverted. Why do I not appear
> >> upside down?
> > because a mirror is a reflecting surface, not a focal pointIf everything's planar you are [of course] correct, but John was
> addressing a much deeper question -- an important one
> that exists at the most-fundamental level of neuroscience.
> To see its stuff, take mind's eye to your local amusement park's
> funhouse, paying careful attention to the non-planar mirrors.
> Bring some gedanken shaving cream and have a go at shaving.
> It's still "reflection", but the waviness of the mirrors make it
> necessary for one to impose a complementary transformation
> between the information that reaches the retina from the mirror
> and the activations of the muscles that control the motion of
> the 'razor'.
> See the difference? Invoking reflection from, say, a bathroom
> mirror as one shaves, without addressing the 3-dimensionality
> of the ambient "forces" in one's external experiential environ-
> ment leaves necessary stuff out of the picture.
> It was this stuff that John was addressing.
> Once the general necessity of accounting for such stuff is
> realized, it's possible to rapidly converged upon its details.
> Using the "mirror" you invoked, for instance, get out your
> gedanken glass cutter and score it vertically [relative to
> a standard horizon] so that it's divided into two equivalent
> halves, crack it [there's no such thing as 'bad luck' :-],
> and, "hinging" along the cracked edge, set the two halves
> at various angles relative to each other . In this way, one
> can flip-flop the reflected image at will -- and it's all still
> It's this sort of manipulation, which is inherently topological,
> that John was addressing, in particular, with respect to how
> and why the visual image, which passes through the eyes'
> lenses and is, by them, everywhere "inverted", still yields
> "upright" images, with faithfulness to all external optics.
> What John was getting at is that a lot happens between
> the physical mirror and "mind's eye' -- all of which is
> the province of neuroscience, most of which is fund-
> amental neuroanatomy. There are great wonders in-
> herent -- that a plane-mirror is totally-unbiased with
> respect to light's directionality, yet when we "look
> into" one, "left" and "right" are reversed, but "up" and
> "down" are not -- even though all light that we perceive
> passes through the lenses of our eyes, there, everywhere
> "inverted" as it travels to the retina.
> So there's 'reflection' involved, but invoking simple
> reflection is insufficient.
> A superficial part of it is due to the fact that our eyes
> are oriented in a horizontal plane, but most of what's
> involved is founded at exceedingly-deeper levels of the
> neuroanatomy. To address all that's entailed, one has to
> literally address every "twist and turn" that exists
> within the neural pathways.
> For instance, no matter where one looks in a 'normal'
> nervous system, everything one sees is precisely-
> ordered with respect to the way the eyes' lenses
> invert all the light that passes through them. The
> great fiber crossings in the medulla, for instance, all
> exists solely in order to achieve the stuff that evoked
> John's comments.
> This because, if the nervous system is to be able
> to converge upon activations of an individual's
> musculature that will, say, enable the individual to
> successfully use a tool in the presence of 'gravity',
> or to walk through a doorway without banging her
> arm, there must be an overall order that enables
> the nervous system to 'know' how to achieve the
> necessary muscle activations.
> See the big problem inherent?
> How does the nervous system ["the brain"] 'know'
> how [and even why] to so orchestrate its activations
> of its host organism's muscles so that the result
> will be behavior that is, more or less, 'appropriate'
> with respect to environmental necessities upon
> which survival of the organism [even us] depends?
> That is really what John was addressing.
> And, although there's a lot that's involved, it's
> all ordered in an awesomely-simple way that
> enables a nervous system to 'know' how [and
> even why] to activate all of the body's musculature,
> practically no matter what routine external stim-
> ulation is experienced [is encountered by; im-
> pinges upon] the nervous system.
> Nervous systems achieve this very-useful [ab-
> solutely-survival-essential] end by doing only
> one thing -- they 'strive' 'blindly' and auto-
> matically to minimize the topologically-distrib-
> uted ratios of excitation to inhibition that are
> occurring within themselves. The easiest way to
> begin see this is to study the way that all neuro-
> anatomical twist, turns and lateral-crossings are
> ordered with respect to the cerebellum's entirely-
> inhibitory outputs [which arise solely from the
> cerebellar Purkinje cells]. Because all of the out-
> puts of the cerebellum are inhibitory, when, say,
> one's arm brushes against an object in the external
> environment, such results in an increase of the
> excitation that the brushed surface of the arm
> passes to the cerebellum. And all the cerebellum
> does is take that little 'mountain' of excitation
> and transform it into a 'valley' of excitation,
> with the topography pereserved, and project
> that 'valley' of excitation back to the muscles
> that control the orientation of the arm. Because
> the topography is, in fact, preserved, a Truly
> wonderous thing happens -- the muscles that
> were most active -- and, so driving the body
> into its encounter with the environmental obstacle --
> rapidly become relatively least-activated and
> the muscles that were formely weakly-activated
> rapidly become relatively most-activated --
> and the arm 'moves away from' its contact with
> the environmental obstacle, thus [typically] saving
> the body from injury.
> Take this simple, extremely-low-level example
> and extend it everywhere within a nervous system.
> It's all exactly the same simple stuff that nervous
> systems are everywhere-organized to achieve:
> minimization of the topologically-distributed ratios
> of excitation to inhibition.
> Every neuroanatomical twist, turn, and crossing
> occurs within 'normal' nervous systems solely
> to establish the means to achieve this one end.
> And all of this was in John's splendid post [even
> his already knowing it, eh John? :-]
> The eyes -- "vision" -- are completely subservient
> to this one simple ordering principle. They do
> nothing that's discordant with respect to it.
> So, if, for instance, it was the case that we were
> not fixed in space with respect to the directed
> force of 'gravity', the left-right/up-down differ-
> ential that John addressed would not be as it is.
> What would exist within nervous systems would,
> then, be whatever it would be that would enable
> them to achieve TD E/I-minimization, and the
> resultant beings, although not like us, would
> survive in their different world just as capably
> as we do in ours, even though there would be no
> "left" or "right", "up" or "down". [Octopusses
> come to mind as and at least partial example.]
> "Reflection" from the planar surface of the mirror
> is actually artifactual with respect to what happens
> within nervous systems.
> This is what John was actually addressing in his post.
> Cheers, folks
> [Yes, it's ken. I'm using this 'funny' UserID in the
> hope that it'll allow me to just be with folks for a
> while before this [9th] machine is rendered useless
> by folks who, for whatever reason, don't like me
> being with you folks.]
More information about the Neur-sci