From: David Rudiak <drudiak.nul> Date: Thu, 08 Mar 2012 14:06:53 -0800 Archived: Fri, 09 Mar 2012 03:41:27 -0500 Subject: Re: Inter-Dimensional Or Demonic >From: Ray Dickenson <r.dickenson.nul> >To: <post.nul> >Date: Wed, 7 Mar 2012 14:55:58 -0000 >Subject: Re: Inter-Dimensional Or Demonic >>From: Gerald O'Connell <goc.nul> >>To: <post.nul> >>Date: Tue, 6 Mar 2012 20:57:31 -0000 >>Subject: Re: Inter-Dimensional Or Demonic >>>From: Ray Dickenson <r.dickenson.nul> >>>To: <post.nul> >>>Date: Sun, 4 Mar 2012 15:08:26 -0000 >>>Subject: Re: Inter-Dimensional Or Demonic ><snip> >>>And, as noted by researchers, the flow of data along the optic >>>nerve is two-way (as with hearing). Clearly the brain is >>>constantly telling the eye _how_and_what_ to see. >>I think you are overstating the case pretty dramatically there, >>Ray. The reTturn path info is probably just instructions around >>attention: moving the antenna, focus etc....There doesn't have >>to be any interpretive data. >>Check the next sentence in that post. The possibility of your >>'purely optical' interpretation was the reason for me next >>providing the data backing - the new-born kitten experimants - >>for 'brain control' of the eye. The new-born kitten experiments show pathology induced in the brain and do NOT show "brain control" of the eye. More below. >>The eye is an optical mechanism (ie. all its parts, including >>the rods and cones, are dedicated to detecting photons) and it >>contains _no_ cortical matter for processing or converting image >>data. No, again wrong. The retina begins as an outcropping of the primordial brain tissue in fetuses and consists of three distinct layers, not just one of photoreceptors. The photoreceptors are primarily transducers, converted light into electrical signals, so they also have properties of nerve tissue (but are derived from cilia, as are the hair cells in the ear that transduce vibrations into electrical signals). Even in the photoreceptors, some processing of the light is taking place, such as setting the light sensitivity of the eye, which can range over a much greater range of magnitudes than film or your digital camera (thus the problem we've all experience taking outdoor pictures where the bright sky is washed out while darker scene details come out too dark--the retina can locally adjust sensitivity and thus accommodate a much larger range of light values). The next two layers are called the bipolar and ganglion cell layers and most definitely ARE neural tissue that does early processing on the visual signal. This involves recoding the raw light/dark/color signals into visual primitives that are assembled into more complex interpretations in the visual cortex. The basics of edge and form detection, light and color constancy, motion detection, and light sensitivity are built right into the retina. The retina is NOT just a passive purveyor of lightness and color values, but actively processing these values. Thus it is only crudely analogous to a film camera or TV camera. The point is the retina does early visual processing and IS brain tissue. Higher vertebrates like ourselves do the vast bulk of visual processing in our large cortex, but lower vertebrates with tiny brains may do a big chunk of processing in the retina, not their brains. The earliest electrophysiological studies of the retina were done in amphibians like frogs and mud puppies, which happen to have bipolar and ganglion cells much larger than higher vertebrates. Thus it was possible to record directly from the bipolar and ganglion cells and learn what they did or did not respond to. One classic paper from 1968 was charmingly titled "What the Frog's Eye tells the Frog's Brain," by Lettvin et. al. The frog has very simple and basic visual needs. It needs to find food and it needs to leap away from danger. That's about it. Corresponding to this, they found four types of processed visual responses in the retina, corresponding to four different types of nerve tissue, which mapped precisely to four different layers in the optic tectum (the only visual "brain" the frog has). One process detects only small, convex moving spots (nicknamed "bug detectors"). The others detect large edges, gross movement, and dimming of light (hence perhaps a predator approaching). Unless a bug is moving, a frog doesn't interpret it as possible food. It is indeed "blind" to its existence because it's retina isn't constructed to detect it. It will starve to death surrounded by motionless bugs. That is how specific the frog's retinal system is (but not ours). Incidentally, the Lettvin paper can be found here: http://tinyurl.com/2dtqbo >>Any such operations could only start in the optical >>tectum, the first connections of the optic nerve into the brain >>(although further evidence - see ref below - says that other >>processing and discrimination takes place deeper in the brain). But early NEURAL processing takes place in the retina. Obviously only a very limited aspect of the visual world passes through the "filter" of the frogs retina (bug or possible predator), but much more of the visual world in our retinas is passed on to our much bigger brains, which we know can recognize much more than just food or foe, but identify and classify millions of objects as well as many kinds of motion (e.g., we can recognize an animal or person by their gait alone). Higher vertebrates like us have much simpler retinas than frogs, passing off the more complex data processing to the brain. You won't find the equivalent of a "bug detector" in a cat or human retina. The main "filter" in our retinas is reducing the light collected from about 100 million photoreceptors in each retina down to about one million fibers in the optic nerve. Signals from multiple photoreceptors in the peripheral retina are gathered into larger "receptive fields", whereas the very central part of the retina where the smallest cone photoreceptors are located, may have a one-to-one correspondence between photoreceptor and optic nerve fiber. Our detailed vision for form is in the center of the eye, whereas our detection of gross detail (which helps us orient ourselves and place gross objects relative to one another in the visual space) and motion lies more and more to the periphery. Correspondingly, the bulk of brain tissue is devoted to processing the central few degrees of our vision, and less to the much larger area of our visual field in the periphery. This was a necessary evolutionary compromise. We would have needed optic nerves the thickness of your wrist and brains the size of a desk to process all of the visual field with the same detail as the central few degrees if there was a one-to-one correspondence between all photoreceptors and all optic nerve fibers. Despite this, our visual systems work remarkably well, still much better than any computer vision out there. In computer vision, to avoid overwhelming the system and trying to process in something like real time, they likewise look for only certain aspects of the visual scene. Any "seeing" system, however complex, is going to have to do this. I can imagine future more complex artificial vision systems than our own small brains can handle, but all vision systems involve compromises and filtering of the scene for certain visual primitives that can be analyzed into more complex attributes. "Seeing" of varying complexity necessarily involves data processing or filtering of the "pure" light image into various attributes that can be used in some way by the vision system. >Therefore if the eye can be 'ordered' to ignore certain photon >arrangements and be 'blind' to certain objects which it >otherwise can optically 'see' No Ray, our eyes are not "ordered" by the higher brain to ignore certain objects. I don't know where you get these ideas. To repeat what I said in an earlier post, even if presented with an extremely novel visual experience which we can't identify from prior experience, we are not "blind" to it. We just don't know what to make of it, but we can still describe it's attributes, such as color, form, luminosity, distance, motion, etc. Don't confuse identification and understanding with basic visual perception. > - as the kitten experiments >demonstrate - that 'order' must come from the brain. Wrong again. The kitten experiments involve creating pathology in the visual cortex, not the retina, by depriving the kittens of normal visual experience, e.g., by suturing one of the eyes shut while the kitten is very young. Neurons in the brain connected to that eye never develop properly as a result and the kitten will have extremely poor vision in that eye (mimicking what can happen in human babies if deprived of normal vision in an eye). The kittens also never develop stereopsis or pure depth perception (which requires both eyes being fully functional), just like humans with similar deprivation. One can even cause more specific deprivations, such as exposing one eye only to vertical stripes and the other to only horizontal ones. As you would expect, each eye ends up being good at detecting the orientation it experiences and poor at the orientation it doesn't, but, again, this occurs in the visual cortex, NOT the retina, and the brain isn't telling the retina what to "see" or not see. >The Profs Ian Stewart & Jack Cohen ('Collapse of Chaos' 1994) in >their chapter 'Eyes Are Not Cameras', show that the purely >optical interpretation of vision is _not_ sufficient to cover >even well known facts - and say "Indeed, it is so complicated >that we currently have no very good idea of just how it works, >and that's one reason why robot vision remains in a very >rudimentary state." p. 155 Objects have more than just visual properties, which is why babies grab, manipulate, throw, bang, mouth, taste, just about anything they see and can get their grubby hands on. So yes, learning to "see" things is more than just a purely optical interpretation, and one of the ways robot vision has badly lagged behind human vision. (Another way it badly lags behind is in having only a minute fraction of the data processing power of the brain.) We live in the complex interactive real world; computers don't. Optical images only have meaning or utility if we know what we can do with them or what they can do to us, which we learn through years of experience. Thus the blind person with their sight restored in later life isn't exactly "blind", but they also have trouble making use of the vision they have, because it is dissociated from the other things objects are to us through our other sensory and motor experience. They are no longer sensory blind, but remain largely functionally blind. >BTW - We primitive humans have gotten far enough to successfully >interfere with the sensory apparatus of various beings (plant >and insect pests - so far as is publically known). It doesn't >take a genius to realize that even slightly more advanced folk >could well be interfering with _our_ sensory mechanisms. But what exactly does that mean? Are you saying they take total control of our brains so that even in the here and now they can appear to be a very different form than they really are? Or is it just a matter of planting screen memories, like we can do ourselves to some extent with drugs and hypnosis. One is messing with the purely sensory apparatus, the other with memory and interpretation, which, again, are not the same things. David Rudiak Listen to 'Strange Days... Indeed' - The PodCast At: http://www.virtuallystrange.net/ufo/sdi/program/ These contents above are copyright of the author and UFO UpDates - Toronto. They may not be reproduced without the express permission of both parties and are intended for educational use only.
[ Next Message | Previous Message | This Day's Messages ]
This Month's Index |
UFO UpDates - Toronto - Operated by Errol Bruce-Knapp