{"id":69,"date":"2022-04-27T07:13:05","date_gmt":"2022-04-27T11:13:05","guid":{"rendered":"https:\/\/pressbooks.library.upei.ca\/danceofphotons\/chapter\/another-problem-with-photons\/"},"modified":"2022-05-12T18:15:45","modified_gmt":"2022-05-12T22:15:45","slug":"another-problem-with-photons","status":"publish","type":"chapter","link":"https:\/\/pressbooks.library.upei.ca\/danceofphotons\/chapter\/another-problem-with-photons\/","title":{"raw":"ANOTHER PROBLEM WITH PHOTONS:","rendered":"ANOTHER PROBLEM WITH PHOTONS:"},"content":{"raw":"
\r\n

THEY\u2019RE NOT COLORED!\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/em><\/strong>p. 58\r\n<\/em><\/strong><\/h3>\r\nPerhaps the most convincing evidence is the changes in hue produced by pulsing single wavelengths of light.17<\/sup> This indicates that hue perception involves a temporal code which was altered by flashing, as well as by the cone neural pathways.\r\n\r\n<\/div>\r\nLet\u2019s consider, \u201cHow could the wavelength information available from photons be made evident in a conscious representation?\u201d That picture in our head is filled to the finest possible directional detail available in the retinal image from point to point variation in the number of photons. Adding some kind of symbol to also indicate the wavelength point by point would obscure the directional detail. Alternatively copying the auditory system, by adding some effect like\u201dtwinkling\u201d would take time to play out, thereby reducing the speed of perception and ability to notice change.\r\n\r\nSomehow evolution hit upon the same kind of solution physicists use when they can\u2019t explain an idea - invent a new \u201cdimension\u201d like strings<\/em>. Color is an additional dimension in consciousness added to the directional detail of the internal image to represent photon wavelength point by point.\r\n

Because<\/strong> photons<\/strong> are<\/strong> not<\/strong> colored,<\/strong> our<\/strong> brain<\/strong> has<\/strong> to<\/strong> do<\/strong> it.<\/strong><\/h3>\r\n \r\n

p. 59<\/p>\r\nThe wavelength information gathered by three types of cones is sent to the brain as impulses along six types of neural pathways:\r\n\r\n\"image\"\r\n\r\nN.B. We are now referring to pathways<\/em> in the brain where the sensations arise, and not to specific things that might be mistaken as being colored.<\/span>Therefore, it is OK to use color names. (Sure beats writing \u201clong wavelength pathways\u201d every time - shortening to \u201clong pathways\u201d, etc. doesn\u2019t work : )\r\n\r\nThese relatively simple<\/em> neural computations in the retina are the first in series of steps analyzing the relative responses of the three cone receptors.\r\n\r\nThe next two figures show the basics of how these computations are done.\r\n\r\n \r\n

p. 60<\/p>\r\nThe red<\/em><\/strong> excitatory<\/em><\/strong> -<\/em><\/strong> green<\/em><\/strong> inhibitory<\/em><\/strong> calculation:\r\n\r\n\"\"\r\n\r\nNote that the LONG wavelength cone absorbs the most photons at 590 nm which looks yellow orange. Pitting the MIDDLE wavelength response against the LONG wavelength response, results in a neural response that peaks at 625, which looks red.\r\n\r\nVarious non-mammalian animals have three or more types of receptors whose wavelength absorption curves are spread out more evenly. Therefore their systems need less processing to achieve good wavelength discrimination. As primates, we use our brain to make up for poor genetics.\r\n\r\nPerhaps that\u2019s how we got started down that road!\r\n\r\nSwitch the excitatory and inhibitory synaptic connections around, and you get a green<\/em><\/strong> excitatory<\/em><\/strong> -<\/em><\/strong> red<\/em><\/strong> inhibitory<\/em><\/strong> pathway.\r\n\r\nFour to go:\r\n\r\n \r\n

p. 61<\/p>\r\nHere is a blue<\/em><\/strong> excitatory<\/em><\/strong> -<\/em><\/strong> yellow<\/em><\/strong> inhibitory<\/em><\/strong> calculation:\r\n\r\nIt explains how \u201cyellow\u201d comes into the picture. Both the LONG and MIDDLE wavelength \"\"cones inhibit the ganglion cell for this pathway. Note that their combined effect is strongest at the mid point between them, 575 nm, which looks yellow to us.\r\n\r\nAn excitatory synapse from the SHORT wavelength cone completes the calculation.\r\n\r\nTo get a yellow<\/em><\/strong> excitatory<\/em><\/strong> -<\/em><\/strong> blue<\/em><\/strong> inhibitory<\/em><\/strong> - - - . Well, you can probably guess.\r\n\r\n \r\n\r\nMake all the synapses excitatory and you have pathway that responds to any wavelength. Even better if all the wavelengths, white light, are present at once. Thereby one gets a white<\/em><\/strong> pathway.\r\n\r\nFinally, make all the synapses inhibitory and nothing happens. What good is that? Next page:\r\n\r\nNerves are not inactive when not stimulated. Their sensitivity makes them a bit unstable. Left alone, they irregularly release a nerve impulse, perhaps 1 or 2 every second or so on average. Yet that is also information.\r\n\r\n \r\n

p. 62<\/p>\r\nThe nervous system is often referred to as being \u201cbinary\u201d - like current digital computers. But that ain\u2019t so. It is actually a trinary system:\r\n\r\nTable 1. Neurons as trinary signal processors.\r\n\r\n\r\n\r\n\r\n\r\n\r\n
impulses per second<\/td>\r\nneuron\u2019s state<\/td>\r\nnumerical equivalent<\/td>\r\n<\/tr>\r\n
0<\/td>\r\ninhibited<\/td>\r\n-1<\/td>\r\n<\/tr>\r\n
1 or 2 random<\/td>\r\nresting<\/td>\r\n0<\/td>\r\n<\/tr>\r\n
> 2<\/td>\r\nactive<\/td>\r\n+1<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\nIt can be just as important to know that there is no light coming from a particular direction \u201cout there\u201d as spotting something bright in darkness. Your reading these black letters proves that point.\r\n\r\nHowever, there is more to getting a black<\/em><\/strong> pathway<\/em><\/strong>.\r\n\r\nSome neurons are so \u201cunstable\u201d they fire continuously unless inhibited. Cone activated inhibitory synapses on these result in a true black<\/em><\/strong> pathway<\/em><\/strong> that actively signals darkness.\r\n\r\nYet there is more. These black<\/em> and white<\/em> pathways join onto two other types of ganglion neurons with alternating excitatory and inhibitory synapses to create white<\/strong> excitatory<\/strong> -<\/strong> black<\/strong> inhibitory<\/strong> and black<\/em><\/strong> excitatory-<\/em><\/strong> white<\/em><\/strong> inhibitory<\/em><\/strong> pathways<\/em><\/strong>. Between them the subtlest differences in shades of gray (i.e. the number of photons) become noticeable.\r\n\r\n \r\n

p. 63<\/p>\r\nThese two pictures illustrate how much information is added by superimposing the information available from photon wavelengths onto the directional detail in a retinal image:18<\/sup>\r\n\r\n\"\"\"\"\r\n\r\nNote how easy it is to see the apples as well as to tell whether they are good to eat.\r\n\r\nThere is a lot more about color than its hues, but those are other stories.19, 20<\/sup>\r\n\r\n ","rendered":"

\n

THEY\u2019RE NOT COLORED!\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/em><\/strong>p. 58
\n<\/em><\/strong><\/h3>\n

Perhaps the most convincing evidence is the changes in hue produced by pulsing single wavelengths of light.17<\/sup> This indicates that hue perception involves a temporal code which was altered by flashing, as well as by the cone neural pathways.<\/p>\n<\/div>\n

Let\u2019s consider, \u201cHow could the wavelength information available from photons be made evident in a conscious representation?\u201d That picture in our head is filled to the finest possible directional detail available in the retinal image from point to point variation in the number of photons. Adding some kind of symbol to also indicate the wavelength point by point would obscure the directional detail. Alternatively copying the auditory system, by adding some effect like\u201dtwinkling\u201d would take time to play out, thereby reducing the speed of perception and ability to notice change.<\/p>\n

Somehow evolution hit upon the same kind of solution physicists use when they can\u2019t explain an idea – invent a new \u201cdimension\u201d like strings<\/em>. Color is an additional dimension in consciousness added to the directional detail of the internal image to represent photon wavelength point by point.<\/p>\n

Because<\/strong> photons<\/strong> are<\/strong> not<\/strong> colored,<\/strong> our<\/strong> brain<\/strong> has<\/strong> to<\/strong> do<\/strong> it.<\/strong><\/h3>\n

 <\/p>\n

p. 59<\/p>\n

The wavelength information gathered by three types of cones is sent to the brain as impulses along six types of neural pathways:<\/p>\n

\"image\"<\/p>\n

N.B. We are now referring to pathways<\/em> in the brain where the sensations arise, and not to specific things that might be mistaken as being colored.<\/span>Therefore, it is OK to use color names. (Sure beats writing \u201clong wavelength pathways\u201d every time – shortening to \u201clong pathways\u201d, etc. doesn\u2019t work : )<\/p>\n

These relatively simple<\/em> neural computations in the retina are the first in series of steps analyzing the relative responses of the three cone receptors.<\/p>\n

The next two figures show the basics of how these computations are done.<\/p>\n

 <\/p>\n

p. 60<\/p>\n

The red<\/em><\/strong> excitatory<\/em><\/strong> –<\/em><\/strong> green<\/em><\/strong> inhibitory<\/em><\/strong> calculation:<\/p>\n

\"\"<\/p>\n

Note that the LONG wavelength cone absorbs the most photons at 590 nm which looks yellow orange. Pitting the MIDDLE wavelength response against the LONG wavelength response, results in a neural response that peaks at 625, which looks red.<\/p>\n

Various non-mammalian animals have three or more types of receptors whose wavelength absorption curves are spread out more evenly. Therefore their systems need less processing to achieve good wavelength discrimination. As primates, we use our brain to make up for poor genetics.<\/p>\n

Perhaps that\u2019s how we got started down that road!<\/p>\n

Switch the excitatory and inhibitory synaptic connections around, and you get a green<\/em><\/strong> excitatory<\/em><\/strong> –<\/em><\/strong> red<\/em><\/strong> inhibitory<\/em><\/strong> pathway.<\/p>\n

Four to go:<\/p>\n

 <\/p>\n

p. 61<\/p>\n

Here is a blue<\/em><\/strong> excitatory<\/em><\/strong> –<\/em><\/strong> yellow<\/em><\/strong> inhibitory<\/em><\/strong> calculation:<\/p>\n

It explains how \u201cyellow\u201d comes into the picture. Both the LONG and MIDDLE wavelength \"\"cones inhibit the ganglion cell for this pathway. Note that their combined effect is strongest at the mid point between them, 575 nm, which looks yellow to us.<\/p>\n

An excitatory synapse from the SHORT wavelength cone completes the calculation.<\/p>\n

To get a yellow<\/em><\/strong> excitatory<\/em><\/strong> –<\/em><\/strong> blue<\/em><\/strong> inhibitory<\/em><\/strong> – – – . Well, you can probably guess.<\/p>\n

 <\/p>\n

Make all the synapses excitatory and you have pathway that responds to any wavelength. Even better if all the wavelengths, white light, are present at once. Thereby one gets a white<\/em><\/strong> pathway.<\/p>\n

Finally, make all the synapses inhibitory and nothing happens. What good is that? Next page:<\/p>\n

Nerves are not inactive when not stimulated. Their sensitivity makes them a bit unstable. Left alone, they irregularly release a nerve impulse, perhaps 1 or 2 every second or so on average. Yet that is also information.<\/p>\n

 <\/p>\n

p. 62<\/p>\n

The nervous system is often referred to as being \u201cbinary\u201d – like current digital computers. But that ain\u2019t so. It is actually a trinary system:<\/p>\n

Table 1. Neurons as trinary signal processors.<\/p>\n\n\n\n\n\n\n
impulses per second<\/td>\nneuron\u2019s state<\/td>\nnumerical equivalent<\/td>\n<\/tr>\n
0<\/td>\ninhibited<\/td>\n-1<\/td>\n<\/tr>\n
1 or 2 random<\/td>\nresting<\/td>\n0<\/td>\n<\/tr>\n
> 2<\/td>\nactive<\/td>\n+1<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

It can be just as important to know that there is no light coming from a particular direction \u201cout there\u201d as spotting something bright in darkness. Your reading these black letters proves that point.<\/p>\n

However, there is more to getting a black<\/em><\/strong> pathway<\/em><\/strong>.<\/p>\n

Some neurons are so \u201cunstable\u201d they fire continuously unless inhibited. Cone activated inhibitory synapses on these result in a true black<\/em><\/strong> pathway<\/em><\/strong> that actively signals darkness.<\/p>\n

Yet there is more. These black<\/em> and white<\/em> pathways join onto two other types of ganglion neurons with alternating excitatory and inhibitory synapses to create white<\/strong> excitatory<\/strong> –<\/strong> black<\/strong> inhibitory<\/strong> and black<\/em><\/strong> excitatory-<\/em><\/strong> white<\/em><\/strong> inhibitory<\/em><\/strong> pathways<\/em><\/strong>. Between them the subtlest differences in shades of gray (i.e. the number of photons) become noticeable.<\/p>\n

 <\/p>\n

p. 63<\/p>\n

These two pictures illustrate how much information is added by superimposing the information available from photon wavelengths onto the directional detail in a retinal image:18<\/sup><\/p>\n

\"\"\"\"<\/p>\n

Note how easy it is to see the apples as well as to tell whether they are good to eat.<\/p>\n

There is a lot more about color than its hues, but those are other stories.19, 20<\/sup><\/p>\n

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