I will be speaking a great deal about femtoseconds or an increment of 10-15 th of one second. It might be worthwhile considering how short this interval really is:
A quote: “The number of femtoseconds in a second is far greater than the number of seconds in a human lifespan”.
The retina is structured at the plane of receptor outer segments of an array of millions of individual nano-antennas that are responsive to the wave nature of light. Individual antennas are spatially dimensioned within the wavelength of light (the ‘near field’) and possess characteristics necessary to function electronically in very fast time.
I propose that this array acquires a very fast succession of completely formed images of the visual scene on a time scale of femtoseconds – thus of the extraordinary number of the order of 1015 images per second
I have previously proposed that it is phononic/solitonic transport of energy from wave absorption space to quantum confined electron endpoint in the structure of each nano-anntenna that provides the short term memory (‘Memristor’) function that allows image formation in this time frame.
And then….it follows from a Poisson calculation of light fluence on the retina in the femtosecond time frame yields the surprising result that the probability of two photons falling on the same site is vanishingly small. The retina is then a ‘photon counter’ and each individual ‘femtosecond frame’ in this succession of images consists of millions of single photon* interactions.
*Deferring to common usage I will continue to use the term ‘photon’ although in the spirit of this work one will recognize that ‘quantized interaction’ from absorbed light wave to quantized electron particle should more properly be used.
I believe that this image composed of single photon interactions underlies the recognized sensitivity of the vision process at this level. It has long been known (as recounted by Albert Rose) that vision can perceive an image that was initiated by a few as 2-10 photons.
This implies that the femtosecond ‘photon image’ acquired at the plane of receptor outer segments is transmitted through underlying retinal processes and the optic nerve to the visual centers of the brain.
This evidence would suggest that the train of ‘single photon’ images obtained at the plane of receptor outer segments, after ‘thermalization’ to human nervous system proportion by biochemical processes in the underlying retina, is transmitted as a coherent (i.e., equally spaced as an oscillation) train of completely formed images through the fiber bundle of the optic nerve to the brain. The slower processes of the biochemical processes of the retina probably ‘slow down the train’ perhaps extending the interval between images but it seems clear that the image as an array of single photon pixels arrives at and is so processes by the brain.
Thus we envision that the train of the order of 1015 / sec images arriving at the visual centers of the brain. This number is incomprehensible to us but probably represents the ‘quantum regime’. Lest one casually dismiss this magnitude as beyond the pale, I have continually noted what I believe to be the seminal nature of a paper by Fleming’s group at Berkeley* reporting femtosecond spectrosscopy measuremnts made on another photosensitive system – plant photosynthesis system. To note: photo absorption in plants uses the same nano-antenna light absorption principle as the retina of the eye although as would be expected in this non-imaging geometry the nano-antenna structures are array in parallel to generate power not an image – the grana and stroma of the chloroplast organelle
* Gregory Engel et al, “Evidence for wavelike energy transfer through quantum coherence in photosynthetic systems”, Nature, Vol 446/12, April 2007
This is in the realm of quantum coherence and it predicts that this time scale will lead to greater understanding of brain function. I note again as we proceed into the femtosecond time regime the measurements made by Engel et al* A quote from that paper seems prescient: “This wavelike (i.e., quantum coherent) characteristic of energy transfer within the photosynthetic complex……..allows the complexes to sample vast areas of phase space to find the most efficient path”.
In the trichromatic nano-antenna construction of the retina each of the millions of individual light interactive sites interact with the wave nature of light in dimensionalities (roughly lambda / 2n) that are within the near field of the light wave, i.e., having lateral dimensions of less than a micron. On the retina these spaces correspond to the center-to-center distance between receptors. This space is immediately adjacent to a smaller quantum confined electron space of nanometer dimension that serves as the absorbing mass and provides the electrical input signal for formation of the visual image.
The lateral dimension of the initial light wave-accepting space between receptors defines, in antenna terms, the specific wavelength of light absorbed at that site. In the retina only three, geometrically-defined wavelengths are detected with these corresponding to the singular long and short ends (700 and 400 nm) of the visual band and, critically, the exact geometrically- determined midband wavelength (550 nm). Biology thus employs precise geometry to decode optical wavelength.
The presence of this fixed wavelength reference point on the retinal surface was predicted by Edwin Land ( his “fulcrum”) and forms the basis for his color theory. It also undoubtedly finally explains the conundrum of the color constancy vision.
Thus, a transition from the wave nature of light to quantized electron particle occurs at each of the millions of light detecting sites of the retina.
The initial interaction of light with the wave-accepting space occurs in the very fast (femtosecond or 10-15 sec.) time frame. Absorbed energy is then transferred via a slower phononic/solitonic mechanism through the thylakoid cell membrane to the adjacent quantum confined electron space. This “thermalizing” mechanism provides a short term memory function (“memristor”) linking the two spaces that undoubtedly allows time integration of visual image information from the quantum time domain to human nervous system proportions.
As antennas, each light interactive site on the retinal surface possesses directional properties, i.e., it can decode the direction of the incident light wave. I have proposed elsewhere the electronic structure that has evolved to accomplish this in these nano-antennas. This substantiates the supposition proposed by some that the Fourier transformation process is inherent in the imaging process.
I have left undefined the nano-antenna response of the retina at eccentricities of ~ 20 degrees. This is the transition region extending from the trichromatic central fovea to ~ 20 degrees devoted to formation of the trichromatic visual image to the solely short wavelength defining, pupil-controlling wide angle light meter formed by the rod-rod appositions of the peripheral retina.
NOTE: The nano-antenna formed by rod/rod appositions is sensitive to the wavelength that precisely defines the short wavelength limit of the visual band. This limit at ~400 nm abuts the biologically damaging UV region of the electromagnetic spectrum. One once again sees the connection between geometry (essentially determined by the diameter of the rod receptor) and biology.
The following curves (that constitute the fundamental finding of this work) derive from a simple counting of receptor appositions (“nano-antennas”) as a function of retinal eccentricity. The non-intuitive central peak that emerges geometrically defines the exact middle of the visual band (550 nm) and is located at 7-8 degrees where the density of rods is first sufficient to completely surround each remaining cone.. This is the “fulcrum” leading to the synthesis of color that Edwin Land brilliantly deduced must be present somewhere in the vision system. It is a ratio of lightnesses falling on either side of this point that forms color. When the overall intensity of light falling on the image formation area falls below a threshold necessary for the eye to obtain a valid ratio – no color! The remainder of the image – now colorless – remains.
But, what is occurring in this transition region? I have understood that a small residual of cone receptors remains with the general receptor distribution at this point is represented by the drawing in the upper right (labeled “periphery”) in Plate 6 – again from Pirenne. Note that this data that has been around for a long time – 1866!
NOTE: I would reiterate that these drawings were made from “fresh – BUT DEAD – retina” and thus will invariably appear distorted. The nano-antenna structure functions in the precise spatial order of the living state.
One might deduce from the figure that cones in this region have a slightly greater diameter that those at smaller eccentricities since something like eleven or more rods are seen surrounding each cone as opposed to the eight at the mid band point (upper left).
This, in turn, would mean, in nano-antenna terms, that the light absorbed at these sites would be of a slightly longer wavelength than exact mid band. In color terms this would mean “slightly towards the red end of the visual band”.
The reason for these sites?
I have come upon the work of S. Berman that is particularly interesting in a number of regards. One paper; A new retinal photoreceptor should affect lighting practice notes a finding that asserts that a new retinal receptor has been found sensitive at 480 nm. The first paragraph of this paper is worth quoting:
“At the end of year 2002 the prestigious journal ‘Science’ described the discovery of a previously unknown mammalian retinal photoreceptor operating at photopic light levels as among the 10 most important scientific breakthroughs of the year. Evidence for such an additional human photoreceptor came from studies of the spectral response of circadian regulation. 2,3 Further advances in vision science, especially this past year, 4 have provided evidence from studies in humans directly confirming the existence of an additional retinal photoreceptor. While there are some small differences in estimates of the peak wavelength between the circadian studies and the pupillary studies, it is likely that these responses are all manifestations of the same photopigment with a peak sensitivity around 480 nm although after including the spectral transmission of the optic media, the peak sensitivity would shift upward to 491 nm for the human eye.”
The pertinent reference from the above:
Abstract from“Seeing More Clearly: Recent Advances in Understanding Retinal Circuitry”, Shigang He, et al,
“Among 10 breakthroughs that Science announced at the end of 2002 was the discovery of a photosensing (melanopsin-containing) retinal ganglion cell (RGC) and its role in entraining the circadian clock. This breakthrough exemplifies the ultimate goal of neuroscience: to understand the nervous system from molecules to behavior. Light-sensing RGCs constitute one of a dozen discrete RGC populations coding various aspects of visual scenes by virtue of their unique morphology, physiology, and coverage of the retina. Interestingly, the function of the melanopsin-containing RGCs in entraining the circadian clock need not involve much retinal processing, making it the simplest form of processing in the retina. This review focuses on recent advances in our understanding of retinal circuitry, visual processing, and retinal development demonstrated by innovative experimental techniques. It also discusses the advantages of using the retina as a model system to address some of the key questions in neuroscience”.
The concept of “light sensing retinal ganglion cells” is new to me. My consideration is with the physics of light interaction with the outer segments of the cone and rod receptors of the retina.
To be clear,
In the trichromatic nano-antenna construction of the retina proposed in this work, individual sites interact with the wave nature of light in dimensionalities that are within the near field of the light wave (i.e., lateral dimensions of less than a micron) with this space immediately adjacent to a smaller quantum confined electron space that serves as the absorbing mass and provides the electrical input signal for formation of the visual image.
The lateral dimension of the initial light wave-accepting space defines, in antenna terms, the specific wavelength of light absorbed at that site. In the retina only three, geometrically-defined wavelengths are detected with these corresponding to the long and short ends (700 and 400 nm) of the visual band and, critically, the exact geometrically- determined midband \wavelength (550 nm).
Thus, a transition from the wave nature of light to quantized electron particle occurs at each light detecting site of the retina.
The initial interaction of light with the wave-accepting space occurs in the very fast (femtosecond or 10-15 sec.) time frame. Absorbed energy is then transferred via a slower phononic/solitonic mechanism through the thylakoid cell membrane to the adjacent quantum confined electron space. This “thermalizing” mechanism provides a short term memory function (“memristor”) linking the two spaces that undoubtedly allows time integration of visual image information from the quantum time domain to human nervous system proportions.
Acting as antennas, each light interactive site on the retinal surface possesses directional properties. This substantiates the supposition proposed by some that the Fourier transformation process is involved in the imaging process.
I will leave this here for now, but might the considerations above have been mistaken for a “completely new receptor”?
I have received a very thoughtful comment regarding my work. I will reply point by point interspersing my thoughts with the text. This may finally get to the fundamental difference between this interpretation that is based on modern physics and the traditional biological view of the retina (I am convinced, however, that my attempt to break through what I term years of misunderstanding will continue to fall on deaf ears!).
For the record, light photons do not “rain down” on retinal receptors interacting with pigment molecules in some statistical “photon catch” scenario ! Rather, this biological structure evolved to detect the wave nature of light interacting directionally with “nano-antenna” spaces formed by the appositions between individual receptors. Furthermore, this interaction occurs in heretofore unconsidered dimensions of space and time that are now at the forefront of our measurement capability (femtosecond spectroscopy, for example). A new understanding of the vision process follows from this realization.
But to the reader…please realize that what I am about is physics – the pure physics, describing in modern nanotechnology terms, light interaction with the outer segment of retinal receptors and ultimately demonstrating where this leads in understanding the vision process. These physics describe an interaction in space and time that is entirely new to vision science in the sub-micron spatial domain and on a time scale that is at the limit of our ability to measure experimentally – femtoseconds. This generally describes the regime of quantum physics. (Although not associated with vision, I note even today a report of a finding of “quantum antenna” structures ‘Quantum antennas’ enable exchange of quantum information between two memory cells. There is much teaching in this report.)
So very much of the vision process is explained by this realization. Further, this is not a new “theory” but exactly explains and is derived from fundamental experimental measurements that have been made in the science of vision that date back to the initial determination of the trichromicity of the process and Osterberg’s 1935 accepted measurements of retinal topology.. The concept of light wave-interactive “nano-antennas” makes clear for the first time that determination of the sensation of “color” does not reside directly in the process of retinal light interaction. This assumption has been a “shortcut” that has taken our thought process far astray. Edwin Land’s seminal work on the perception of color is finally explained together with such historically unexplained phenomenon as the color constancy of vision and finally, a quantitative understanding of the eye’s ability to discern the interaction of single quanta (photons).
I have been told on occasion that “if I only had studied biology…I would understand the situation etc.” (this point will become evident in the text that I will critique below). It seems clear that in these later years vision science has become the province of biologists, geneticists, etc, with precious little physics input. Indeed, I suppose there seemed very little that physics could add if the reaction time of the eye was accepted in the biophysical sense as functioning in the millisecond time domain.
In this regard, I find interestingly that the most cogent contemporary vision results are in the engineering discipline of computer vision (I have noted for, example, work in this field on a spiral algorithm for forming the visual image that is in concert with this work).
But (finally) to the Comment (original in italics with my response in capital letters):
“Blue” cones do exist. We know this. We have isolated them. We have tested their responsiveness in the retina in vitro and in vivo. We know they are different from “Red” and “Green” cones. We know their connections to ganglion cells and from there on in the LGN and visual cortex. They do exist.”
THE ENTITIES THAT I WOULD PROPOSE YOU HAVE ISOLATED SHOULD PROPERLY BE TERMED “BLUE SENSITIVE LIGHT INTERACTION SITES“. IN THIS WORK THESE SITES ARE SHOWN TO CORRESPOND TO THE HISTORIC AND ACCEPTED MEASUREMENTS OF THE DENSITY AND DISTRIBUTION OF BLUE SENSITIVE CONES THAT YOU REFER TO. THESE SITES ARE NANO-ANTENNAS FORMED BY THE STATISTICALLY DISTRIBUTED, AND RARE NEAR THE FOVEAL EDGE, ROD-ROD APPOSITIONS. I HAVE CRITIQUED IN-EXETENSIO THE IN-VITRO MEASUREMENTS THAT I BELIEVE YOU MUST REFER TO – AND FOUND THEM VERY WANTING – INTERROGATING A SINGLE RECEPTOR LENGTHWISE ETC WITH ALL OF THE ATTENDENT QUESTIONS. THE IN-VIVO MEASUREMENTS MIGHT REFER TO THE WORK OF ROORDA ET AL AND, AS I HAVE EXPRESSED, THESE MEASUREMENTS AGREE AS TO POSITION AND DENSITY EXACTLY WITH THE NANO-ANTENNA FINDING – NO ORDERED “MOSAIC”.
I BELIEVE THAT THE IDEA THAT SUCH CONES EXIST DERIVES FROM AN ATTEMPT TO SEE AN ORDERED “TRICHROMATIC MOSAIC” THAT WOULD BE THE ANALOGUE OF PHOTOGRAPHIC FILM WITH THIS THINKING CONTINUING EVEN TODAY. THE REAL ORDER IS THE FINDING IN THIS WORK OF A TRICHROMATIC, NARROW WAVELENGTH-RESPONSIVE ORDER THAT DERIVES UNIQUELY FROM THE EVOLVED STATISTICAL MIX OF TWO SIZES OF RETINAL RECEPTORS .
“The conformation of cones in the retina is basically random”
I REALLY DO NOT UNDERSTAND SUCH A STATEMENT. MEASUREMENTS OF THE TOPOLOGY OF THE RETINA CONSISTENTLY SHOW THAT THE ALL-CONE FOVEA IS COMPOSED OF HEXAGONALLY CLOSE PACKED CONES AND THAT THE POINT AT 7-8 DEGREES – THE “YELLOW SPOT” –SURPRISINGLY EXHIBITS COMPLETELY ORDERED OCTAGONAL PACKING.
“Only in the fovea midget cones are virtually the only population, and with increasing eccentrities (sic) they become sparser. It is true that midget cones in the fovea are arranged hexagonally, and rods in greater eccentricities octagonally – it is the most efficient way to pack things together.”
THIS SEEMS TO AGREE WITH MY ABOVE STATEMENT BUT, WHAT ARE “MIDGET CONES”? I REALIZE THAT THERE IS SOME DIFFERENCE ACROSS THE RETINA IN THE SIZE OF CONES BUT I WOULD PROPOSE THAT THE GENERALITY THAT TWO (MAJOR) SIZES OF RECEPTORS – CONES AND RODS – DESCRIBES RETINAL TOPOLOGY.
“But this doesn’t mean much other than that cones are quite sparse outside the fovea – their arrangement is random and it’s not true that there is one cone in the centre of an octagonal arrangement of rods.”
PLEASE REFER TO PLATE 6 FROM PIRENNE’S “VISION AND THE EYE” WHERE THE COMPLETE OCTAGONAL MOTIF IS DIAGRAMMED. THIS IS DATA THAT WAS OBTAINED SOME SEVENTY YEARS AGO !.
“Remember, the retina is a biological apparatus – it is not precisely arranged and cannot be so”
THIS IS THE CRUCIAL POINT OF THIS WORK AND I WANT TO EXPRESS IT AS CLEARLY AS I CAN. THE NANO- (“NEAR FIELD” OF OPTICAL WAVELENGTH) SPATIAL DOMAIN IN WHICH NANO-ANTENNAS FUNCTIONS ONLY IN THE LIVING STATE OF THIS BIOLOGICAL MATERIAL. IT’S SPATIAL ORDER IS EXQUISITELY EXACT. ELECTRON MICROGAPHIC VIEWS OF BIOLOGICAL MATERIALS REPRESENT THE DISTORTED STATE OF DEAD TISSUE AND HAS HISTORICALLY OBSCURED THE PRESENCE OF THIS NANO-ANTENNA MECHANISM.
“It is not the distribution of cones and rods that mediates vision at the retinal level, rather the underlying connections between horizontal and amacrine cells and other cones and bipolars, that determine how things are put together”.
THIS GETS NTO THE UNDERLYING SLOWER BIOPHYSICAL (OR CHEMICAL) SIGNAL PROCESSES THAT I DO NOT DISPUTE. THE NANO-ANTENNA LIGHT INTERACTION SITES CERTAINLY CONNECT WITH THESE UNDERLYING BIOPHYSICAL LOGIC FUNCTIONS.
“Rods play no role in colour vision”
CONE-ROD NANO-ANTENNA APPOSITIONS AT 7-8 DEGREES OF RETINAL ECCENTRICITY FORM THE GEOMETRICALLY DETERMINED MID-BAND WAVELENGTH NECESSARY AS EDWIN LAND FOUND UNDERLYING THE SENSATION OF COLOR. THIS SEEMS TO PARROT THE ERRONEOUS THOUGHT THAT “RODS DETECT“BLACK AND WHITE” – SEE MY LAST COMMENT ON SCOTOPIC AND PHOTOPIC VISION .
“They saturate at very low light levels. They DO still signal at higher light levels – but that’s why cones are so much less sensitive.”
IT IS THE LARGE TOTAL AREA OF ROD-CONTAINING RETINA THAT HAS LED TO THE HISTORICAL MISINTERPRETATION THAT RODS ARE MORE SENSITIVE TO LOW LIGHT LEVELS.
“For a cone to signal light, the signal needs to be about 12 times more than that a rod can possibly signal. Otherwise there’d be too much noise.”
AS EXPLAINED IN THIS WORK, “NOISE” – AND I PRESUME THE WRITER MEANS ELECTRICAL NOISE – IS TIME SENSITIVE – IF SUCH NOISE CORRESPONDS TO RANDOM ELECTRONS, THE SHORTER THE “TIME WINDOW” THE LESS NOISE. AS LONG AS ONE CONSIDERS THAT THE VISON PROCESS OPERATES IN THE SLOW MILLISECOND TME DOMAIN ONE WILL THINK THIS WAY. NOISE IS ELIMINATED IN THE ULTRA-SHORT FEMTOSECOND TIME DOMAIN AND THIS EXPLAINS AS I HAVE NOTED THE ABILITY OF THE EYE TO “NOISELESSLY” – IN CONCERT WITH A SIMPLE POISSON CALCULATION – DETECT SINGLE QUANTA…PLEASE!
“It is not taught that rods are “light or dark” detectors. Far from it. We know that rods’ primary role is vision in very low light levels – night vision basically”
AS I NOTE ABOVE
“There are people who are born without cones – they only see black and white (well actually a bit more green),”
AS THEY SHOULD – THEY HAVE NO ADMIXTURE OFTWO SIZES OF RECEPTORS TO FORM THE GEOMETRIC NANO-ANTENNA BASIS FOR LAND’S COLOR PERCEPTION.
“and they need to wear special sunglasses because otherwise in photopic conditions they wouldn’t see anything. “Light or dark” detection is mediated by a separate system”
AGAIN, SEE MY LAST COMMENT ON PHOTOPIC AND SCOTOPIC VISION.
“Every cone synapses on two separate populations of bipolar cell – an “OFF” population which expresses ionotropic glutamate receptors, thus depolarizing the cell when the cone releases glutamate, which happens in the dark – remember cones hyperpolarize to light. This population signals a reduction in light levels compared to background. The “ON” population carries glutamate GPCRs (mGluR6), which initiate a cascade in response to glutamate which hyperpolarizes the cell – meaning that in the absence of glutamate and thus presence of light, they fire.”
MORE BIOPHYSICS THAT I ACCEPT – BUT NOT RELEVANT HERE.
“Anyway, point is: I think your idea that the distribution of cones and the physical properties of light and the retina can underlie certain things in vision has merit and should be explored further. But please, do not dismiss what we know about the biology of the retina. I think that if you better examined our current knowledge of the retina, you would be able to more precisely modulate your theory.”
My thoughts here elicit many queries so I will revisit the subject. The distinction between the purported existence of two separate vision systems – “color sensitive cones” and “black and white sensitive rods” – represents perhaps the most fundamental error that has been passed down in the literature of vision science and is even today universally taught to students of the subject.
For the reader who has been so educated I would propose that, following the realization that light wave-accepting, nano-antenna dimensionalities are central to light interaction with the retina, this dogma is completely erroneous.
In actuality, there is only one continuum controlled by the pupil of the eye contracting and dilating the diameter of the opening from a light constricting 2 millimeters during daylight (photopic) condition to a fully open 7 millimeters for low level (or scotopic) night vision. Under scotopic (night vision) condition the pupil is fully open allowing what light that is available to fall on the larger area of the short wavelength (“blue”) sensitive peripheral retina. Rods themselves are not more sensitive to light (for which there has never been experimental evidence) but rather it is light interacting on the totality of rod area of the peripheral retina that has historically given this impression.
As taught in this work, it is the peripheral rod-containing retina beyond 20 degreees sensitive to the short wavelength (again “blue”) end of the visual band acting as a “wide angle light meter” that controls pupillary constriction. It is not simply the intensity of light but also precise light wavelength that controls this function.
For example, the following text is abstracted from Wikipedia:
“Scotopic vision is the monochromatic vision of the eye in dim light. Since cone cells are nonfunctional in low light, scotopic vision is produced exclusively through rod cells. Vision in normal light with functioning rod cells is photopic vision”.
That “cone cells are non-functional” (or “shut down”) - there is just no direct experimental evidence for such an assertion!
That “scotopic vision is produced exclusively through rod cells”… how on earth? …invoking what mechanism?
Scotopic and photopic vision have historically been presented as two separate systems. This conclusion follows from the general observation that the sensation of color disappears at low levels of illumination giving the idea that, what has been thought to be (again erroneously) the source of color – the cones – “shut down” at this point. What is left is “monochromatic” sight that must be ascribed to the response of rod receptors- thus a ”black and white” image.
Following from the realizaton that light interacts as a wave with nano-antennas at the plane of receptor outer segments, it becomes instantly clear that there is really only one system.
THE BASIC FINDING OF THIS WORK:
“The sensation of color derives from, precisely as Edwin Land described, the eye obtaining a ratio of light intensities in the region from the central all-cone (“blue blind” according to George Wald) fovea to ~20 degrees. This region is bisected by the geometrically determined mid band (i.e. 550 nanometers) point at 7-8 degrees- Land’s “fulcrum”. When the level of light falls to a point below where a meaningful ratio can be obtained the sensation of color ceases but monochromatic vision remains – the “black and white” image.. The predominance of rod receptors that form the peripheral retina function as a “wide angle light meter” controlling pupillary constriction and the light level that is allowed to fall on the retinal surface.
THUS A FUNDAMENTAL PHENOMENOLOGICAL OBSERVATION HAS BEEN MISINTERPRETED.
But, if one must classify two types of vision these are the proper definitions:
Scotopic vision: “Under low light level conditions the rod receptors of the peripheral retina are linked together (as has been historically shown) to act as a “wide angle light meter” with the exact short wavelength limit of visual response (~400 nm) controlling pupillary constriction, dilating the pupil of the eye and admitting the maximum amount of light to the retina. Under these conditions light intensities of the three primary wavelengths that interact with the image-forming portion of the retina (from the fovea to 20 degrees) are insufficient to activate the “Land color mechanism”, i.e., there is insufficient intensity incident on either side of the geometrically determined mid-band (550 nm) reference point at 7-8 degrees of retinal eccentricity to allow a ratio to be obtained and the hues of color perceived. The historic misconception that “rods detect black and white” is explained.
Photopic vision: “Under normal daylight levels of illumination the three primary light intensities abstracted by the retina are sufficient to activate the “Land color mechanism” as defined above and the the hues of color are perceived superimposed on the visual image. The peripheral rods, as above, constrict the pupil controlling the intensity of light entering the eye to levels that will not damage the retina.
There is only one “system”!
In the last comment I noted an apparent similarity in the seemingly octagonal symmetry of solid state nano-pillars grown on silicon by a UC-Berkeley group with the octagonal motif seen in the biological retina of the eye. I think potentially important is their finding of laser behavior in the nano-pillars that they have grown. I will remind the reader that perfect octagonal symmetry * is present on the retina of the eye at 7-8 degrees of eccentricity where statistically the density of rods is first sufficient to completely surround each of the diminishing number of cones. The following figure that illustrates this is taken from Plate 6 of Pirenne’s VISION AND THE EYE (Chapman and Hall, Ltd., 1967).
* As I have previously noted, these types of microscope drawings or electron micrographs represent views of non-living sections of tissue and thus present necessarily distorted views deriving from excised, sliced, frozen, microtomed, etc. tissue samples. Nano-antennas, however, function in the exquisitely fine spatial order of sub-micron (<10-6 meters) space. One must therefore be very careful in viewing these types of figures. In this case, with the ratio of dimensions of cones and rods approximating 1.8:1, an octagonal symmetry must occur at this point where rods completely surround cones.
This proclivity for formation of complete octagonal symmetry deriving as it does from an overall statistical distribution of receptors has always seemed strange to me and must ultimately be explained.
In the nano-antenna explanation of light interaction, these individual octagonal sites uniquely provide the geometrical definition of the precise middle of the visible band, i.e., 550 nanometers. The density of these sites peaks at a retinal eccentricity of 7-8 degrees forming a radial band surrounding the central fovea. I have noted that this band represents the wavelength “fulcrum” * that Edwin Land from his color vison experiments predicted must be present and that this evidently explains the phenomenon of the color constancy of vision. Biology makes use of spatial geometry as a wavelength reference – there is no need for an imagined ‘spectrometric’ function! * “…we have learned that the eye must have a fantastic mechanism for finding a balance point within a band of wavelengths”…Edwin Land It should be clear to the reader that this radial band extending from the edge of the fovea to ~20 degrees (peaking at 7-8 degrees) consists of nano-antenna light detection sites all of which have the same narrow wavelength response. This is NOT the curve of spectral response that is seen in every text on the eye. Rather, this is the result of a geometrically determined constant spatial dimension. In antenna terminology it represents a narrowly tuned “high Q” situation. This is as far as I had proposed. The Berkeley result, however, introduces an additional (and exciting!) possibility . A finding that these nano-antenna sites harbor laser excitation would mean the presence of a further and fundamental wavelength narrowing beyond the high-Q description along with the implications of laser directionality at each site. There are both temporal and spatial considerations here. First, one must keep in mind that the basic nano-antenna light interaction process with the receptor outer segment structure occurs in the femtosecond (10-15 sec.) time domain (the retinal isomerization ‘signal producing’ event has long been known to occur in this time frame). This is in essence the “residence time” for light to interact with this micron length structure and one must consider only processes that occur in that time domain. The Berkeley group proposes that helically propagating optical cavity modes (essentially a rotation of the light wave) underlie the laser emission that they report. They claim that this occurs within the 300 nanometer dimension of a single nano-pillar (my thoughts on this below). It is the possibility of a similar rotational motion occurring in the biological nano-antenna structures of the retina that interest me. I will simply note that such a reflective helical motion in the micron length of a nano-pillar would have to occur in the very fast (femtosecond) time domain as discussed above. Spatially, I question that this helical reflection is occurring within the 300 nanometer dimension of a single pillar as the authors believe, i.e., within the near field of light wavelength. It seems to me that such a finding would be at issue with recent results of Mazur’s group at Harvard (see the reference to this work in previous comment) where when a light guide (or cavity) is reduced to this dimension, light, via an evanescent wave phenomenon, travels outside of the light guide. Further, the Mazur work shows that as the diameter is reduced more light energy flows around the body of the guide itself. What caught my attention initially in reading the news release of the Berkeley result (SCIENCE NEWS Engineers Grow Nanolasers on Silicon, Pave Way for on-Chip Photonics ) was the presence of an octagonal ‘surround’ or aura of what I thought at that point was the actual laser emission. (it turned out in a subsequent reading of their paper that this figure was a simulation).
However, in the figure itself, and in their following discussion, they seemingly want to visualize this emission as hexagonal although there are eight distinct elements present – and the surrounding octagonal aura. I might hazard a guess that the outer (yellow colored) sources of emission pertain to surrounding cells….but…? My specific question about the Berkeley result would be their proposal that the source of laser emission is within a single 300 nm nano-pillar.I certainly stand to be corrected but this seems to present a dilemma relative to the above noted experimental results of the Mazur group.
In the Berkeley experiments the light beam used to excite laser action is, as they note, of approximately one micron in diameter. This area could encompass the excitation of many nano-pillars and could support the teaching of the retina that light interaction occurs with nano-antenna groupings of nano-pillars. It is difficult to tell from the Berkeley paper whether any spatial order of silicon nano-pillars exist in their growth method that wold support emission from nano-antenna groupings. This may be so, however, considering the single crystal nature of the underlying silicon growth substrate. But…?
An additional dilemma – the “geometric nano-antenna rules” taught by light interaction with the biological retina would indicate that single wavelength (laser) emission should be the product of a grouping of nano-antennas all of the same diameter – in other words, an hexagonal motif. ??? An octagonal motif would mean that two discrete diameters of nano-antennas would be present ..and that the ratio of their diameters would be approximately 2:1. This is not apparent or even likely in the silicon nano-pillar structure. Why then the indication of the octagonal motif?
We can now begin to wander around in the area of “intense speculation” – speculation uniquely made possible by the nano-antenna explanation for light interaction and the important Berkeley laser result. The laser emission that they propose essentially involves a helical ‘internal reflection’ around, or within, the hexagonal cavity that they visualize. Whether this reflection exists within the quantum realm of the atomic structure of a single pillar as they believe or within a larger spatial grouping or motif of pillars is not important here. The point to consider is the possible existence of some form of interaction between, in their visualization, hexagonal elements.
There may be reason to believe that a wave-guiding mechanism for such interaction occurs in the biological structure of the retinal motif. I had always assumed that the rhodopsin/retinal complexes contained within individual thylakoid disks of the outer segments diffuse as monomeric units in the fluid membrane structure. A recent finding The G protein-coupled receptor rhodopsin in the native membrane (Dimitrios Fotiadis et al) indicates that the complexes form spatially ordered dimer structures.
I would remind the reader again that even these indications of order represent sections of dead tissue and not the living state where nano-antenna mechanisms function!
This order in the biological realm, in turn, introduces a relevant paper Nanopillars Photonic Crystal Waveguides (D. N. Chigrin et al). The abstract of this paper:
Abstract “We present a novel type of a waveguide, which consists of several rows of periodically placed dielectric cylinders. In such a nanopillars photonic crystal waveguide, light confinement is due to the total internal reflection, while guided modes dispersion is strongly affected by waveguide periodicity. Nanopillars waveguide is multimode, where a number of modes is equal to the number of rows building the waveguide. We perform a detailed study of guided modes properties, focusing on possibilities to tune their frequencies and spectral separation. An approach towards the specific mode excitation is proposed and prospects of nanopillars waveguides application as a laser resonator are discussed”.
Might spatially oriented dimer arrays of rhodopsin complexes within the thylakoid disks of retinal receptors provide the directional connective interaction between individual receptors in the larger hexagonal or octagonal groupings to form a laser emission?
To this point I have considered the reason for the spatial (hexagonal or octagonal) nano-antenna structures might be to accept various angles of polarized light. This seemed to be consistent with behavior of the eye in this regard. The possibility of laser emission opens up many new areas of thought! Further, the introduction of rotational motion (in the femtosecond time domain) might lead to an explanation for the association that I have made of the octagonal motif with a spatially symmetric epitrochoidal figure. As I have noted, such a symmetric epitrochoid results from a ratio of dimensions of 1.8:1. that corresponds to the ratio of diameters of retinal cone and rod receptors. Formation of an epitrochoid , however, requires the rotation of “something around something” that I have not been able to imagine in this light interaction. May laser emission provide this answer? I will present again the epitrochoidal figure and its relationship to retinal topography:
GCH Oaji,CA 2.12.11
I have noted on numerous occasions that this spatial nano-antenna explanation of the vision process opens entirely new avenues for thought and have pointed out an increasing number of these. A current development reported in SCIENCE NEWS Engineers Grow Nanolasers on Silicon, Pave Way for on-Chip Photonics would seem to present one such avenue.
One might go on to read the complete NATURE PHOTONICS on-line paper “Nanolasers grown on silicon” referenced in the above release.
The authors emphasize in this solid state effort the challenge of growing expansion mismatched materials adjacent to one another. The basic point here, however, is the nano-pillar structure that is grown and the dimensional similarity – nanometer diameter and micron length – to the biological receptors of the retina.
What first struck me was the following figure from the news release (but does not appear in the NATURE PHOTONICS paper):
The octagonal symmetry jumps out at you – although the authors seem to be attempting to “hexagonalize” the motif. From the figure, note the octagonal white “surrounding aura” emanating from what appear as eight individual nano-pillars (although two of the elements – top and bottom – are of smaller dimensions than the other six).
To remind – this nano-antenna explanation for light interaction with the retina finds that the octagonal motif of rods-around-cones at 7-8 degrees of retinal eccentricity geometrically defines the exact mid band point of the visual band and, further, that this octagonal motif seems to be present in the distribution of visual receptors in seemingly all (?) species.
I had thought initially that the figure represented the laser emission quoted by the authors and that this emission emanated from an octagonal arrangement of individual 300 nanometer (their measurement) pillars. This turns out as becomes clear in the NATURE PHOTONICS paper not to be the case. The authors believe that laser emission represents an emission from a single subwavelength nano-pillar. Now, this may be the case but I just do not understand it (and beg to be illuminated). Their quote: “Whereas traditional Fabry–Perot modes are inhibited by the interface between InGaAs and silicon, helical modes can strongly localize light within nanopillars of even subwavelength dimensions…”
I must add, importantly, I had not realized until reading the full paper that the above figure represents a simulation and not actual laser emission as I had first assumed.
As I have previously written in OPTICAL LIGHTGUIDES HAVING DIAMETER SMALLER THAN THE WAVELENGTH OF LIGHT, it has recently been found ( Tong et al, “Single-mode guiding properties of subwavelength silica and silicon wire waveguides” , OPTICS EXPRESS, Vol.12, No.6, 22 March 2004) that when a fiberoptic lightguide is reduced in diameter to dimensions less than light wavelength (i.e., less than ~0.5 micron or 500 nm), instead of being transmitted through the interior of the guide, light flows around (or on the “outside of”) the guide itself. A further finding was that the more the diameter of the guide is reduced the more light flows outside.
Quoting a popularized description of this finding from a Nanotechnology website:
“Silica Nanowires Thinner Than The Wavelength of Light”
“Marrying fiber optics with nanotechnology, scientists at Harvard University have created silica wires that are far narrower than the wavelength of light yet can still guide a light beam with great precision. The wires, about a thousandth the width of a human hair, function with minimal signal loss even when their walls accommodate well under half the breadth of a single light pulse. A team led by Harvard’s Eric Mazur and Limin Tong, a visiting professor from Zhejiang University in China, reports the work in the Dec. 18 issue of the journal Nature. “You wouldn’t normally imagine that a baseball could pass through a garden hose, but these nanowires appear able to handle exactly that kind of wide load,” says Mazur, Harvard College Professor, Gordon McKay Professor of Applied Physics and professor of physics. “In some cases light is propagating along wires just one-third the width of its own wavelength. It’s almost as if the wire serves as a rail to guide the light rather than funneling it in the traditional sense.” The nanowires carry light via evanescent waves that envelop the slender filaments. If two of the wires touch, light can jump directly from one to the other, something that’s not possible with conventional fiber optics. Although as thin as 50 nanometers, the wires created by Mazur and Tong are up to two centimeters long, making them faintly visible to the naked eye. They display impressive resilience and flexibility, curling easily into light-conducting loops whose diameter is just a tiny fraction of a millimeter.
I have proposed that this finding provides a fundamental basis for this nano-antenna explanation of light interaction with the external-to-the-lightguide evanescent wave forming the necessary connection between adjacent receptors.
The Berkeley result seems inconsistent with this –but again, I stand to be corrected! They seem to be attempting to “hexagonalize” what otherwise seems to be an octagonal motif.
I might believe in reading the full NATURE PHOTONICS paper that the source of the laser emission that they observe (Fgiure 3, f,g,and h) might actually be the cavity formed by an octagonal arrangement of individual nano-pillars. Note that their other figures (3 b, c, and d and Figure 4) are simulations. Note that the external laser beam used to excite the nano-structure is one micron in diameter
The laser emission result, however, seems real and could be important to further understanding light interaction with the retina!
Importantly, the authors propose an internally-reflective helical mechanism underlying laser emission – that, in my view, could equally result from the octagonal motif of individual nano-pillars as I surmise.
This “rotational motion within the octagonal structure” potentially provides thought for a proposal that I have made that the geometry underlying such a structure seems consisitent with the formation of a mathematical epitrochoid. An epitrochoid, however, derives from “a point on a smaller circle rotating about a larger circle” , i.e., rotational motion. Outside of some light polarization effect I have not been able to see such motion.
The symmetry of the octagonal motif has always fascinated me.
For the quantum physics minded biologist, I have not previously considered any spatil order in the many rhodopsin complexes resident in the lateral thylakoid membrane of receptors. I do remember seeing a paper describing a dimer-like order to these complexes. A sijmple search today finds “Nanopillars Photonic Crystal Waveguides” (D. N. Chigrin et al, Progress in Electromagnetic Research Symposium 2004, Pisa, Italy, March 28 – 31) where a dimer-like order of nano-pillars is studied a directional waveguides. This perhaps adds to my thought that there may be a laterally directional function operative within each individual receptor (or nano-pillar). This may underpin the finding of the Berkeley paper of a helical aspect to the light interaction. I believe that such an interaction would obviously function in the femtosecond (10>-15 sec) time domain and be contained within the cavity formed by the octagonal ring of subwavelength dimensioned retinal receptors
I recommend this book of essays by Victor Weisskoph particularly to the younger generation of scientists (or students interested in science) who are really the audience to whom this work is addressed. Weisskoph had the particular gift of being able to explain physics – particularly quantum physics – lucidly (another physicist who had this gift was David Bohm).
A bit of the first essay from the book “The Life of a Scientist”:
“A physicist enjoys certain obvious priveleges in our society. He is reasonably paid; he is given instruments, laboratories, complicated and expensive machines, and he is asked not to make money with these tools, like most other people, but to spend money. Furthermore, he is supposed to do what he himself finds most interesting, and he accounts for the money he spends to the money givers in the form of progress reports and scientific papers that are much to specialized to be understood or evaluated by those who give the money – the federal authorities and, in the last analysis, the taxpayer…….”
(the underlining is mine!)
The Nobel Prize in Physiology or Medicine 1967 was awarded jointly to Ragnar Granit, Haldan Keffer Hartline and George Wald “for their discoveries concerning the primary physiological and chemical visual processes in the eye”
Wald’s Nobel Lecture The molecular basis of visual excitation was presented on December 12, 1967. I particularly like the opening paragraph:
“I have often had cause to feel that my hands are cleverer than my head. That is a crude way of characterizing the dialectics of experimentation. When it is going well, it is like a quiet conversation with Nature. One asks a question and gets an answer; then one asks the next question, and gets the next answer. An experiment is a device to make Nature speak intelligibly. After that one has only to listen”.
Further in the text Wald describes the “distribution of color function over the normal human retina”. This description, specifically his Figure 15, is precisely consistent with my finding that “nano-antenna” receptor appositional sites form the light interaction centers on the retina.
George Wald was an experimentalist
who objectively reported his findings even when (as I view it) they were at odds with the contemporary vision paradigm. His data for this distribution of “color centers” is totally inconsistent with the thinking of the time that ”cone receptors detect color” and rod receptors “possess greater sensitivity and a black and white response”. This is a mistaken belief (again, in my view) that persists even to this day and that has become dogma in the field of vision science.
Wald first reports that the central all-cone foveal fixation area (i.e., to 1 degree of eccentricity) is “blue-blind”. He had previously published this finding in a paper “Blue-Blindness in the Normal Fovea”, JOSA, Vol. 57, No. 11, November 1967, to which I have repeatedly made reference. This must mean that there are .no “blue sensitive” or “S” cones in the fovea – and the fovea contains >99% of all of the cone receptors. This has presented an historic dilemma for
which I can find no answer in the literature of vision. Wald’s finding seemingly has just been ignored preferring to envision a “retinal mosaic” as some sort of biological analogue of photographic film.
He goes on to state that “from there to about 20-30 degrees from the fixation point is trichromatic”.
This is the exact retinal area that I have proposed is involved in formation of the visual image. Trichromicity, however, is seen in the nano-antenna order that is derived from the statistical distribution of the two types of receptors. This order is comprised of two regions whose lateral extensions correspond to the long and short wavelength limits of visual response separated by the geometrically-determined mid band reference point (the “Land point”). The subsequent (in the bran?) sense of “color” is derived from a synthesis of the light interaction from these two regions.
Regarding this mid band reference point, in the morphology of the retina there is obviously some tendency for rods to associate with single cones forming, at 7-8 degrees, a complete octagonal “eight rods around each cone” spatial order. It is this spatial order forming the 550 nm wavelength that, in addition to explaining color vision, is the basis for the heretofore unexplained color constancy of vision.
Wald goes on to state: “beyond this range, to perhaps 70-80 degrees out, the retina behaves as though red- or green- blind; and still further out as colorblind (monochromatic)”. This again is precisely as I have proposed – this region is populated entirely with rod receptors (albeit a very few widely distributed remaining cones). It is not at all involved in the image formation process but functions at the short wavelength end of the visual spectrum as a wide angle “light meter” controlling pupillary constriction and light entrance into the eye.
I have used the following figure to summarize the sequence of events involved in the light energy absorption process at each nano-antenna site formed by receptor appositions at the plane of their outer segments. This translation from light wave to electron particle occurs in the near field of the light wave (i.e., at spatial dimensions of less than a micron) and in the femtosecond time domain:
The axial length of receptor outer segments approximates 50 microns. Assuming an index reduced speed of light the “light interaction time” with each segment will be of the order of a few picoseconds (10-12 seconds).
Consider that this interaction as being subdivided into the tens of millions of individual nano-antenna sites on the retina. Thus millions of simultaneous singular interactions are occurring at this retinal plane.
Remember that radially extending from the fovea to approximately 20 degrees the image is synthesized from only three discrete nano-antenna responses that correspond to the ends and the geometrically-determined precise middle of the visual band.
It seems not often to have been realized but a Poisson calculation that takes into account this density of sites illuminated with a normal light fluence (or density of, as defined in this work, ”quantized interactions”) shows that the probability of simultaneous light interactions on an individual site is vanishingly small.
I have proposed that this calculation forms the basis for an explanation of the well known ability of the eye to detect single quantized interactions (photons) at low light levels (i.e., in darkness). Each light detection site on the retina interacts with only a single quantized interaction at time!
The millions of retinal sites are simultaneously illuminated with single light interactions. One gets the first indication here of “coherence” or the formation of an image.
It seems logical at this point that some form of memory function might exist to “hold this coherent visual scene for subsequent processing” or, perhaps in other terms to “simultaneously thermalize” this plane of events so that they can subsequently be used in all of the biological aspects of the vision process”. In moving picture parlance this would be called “frame grabbing”.
I have proposed that this is the function of the slower phononic transfer of the light energy absorbed at each site and transported along the length of lipid molecules forming the membrane of the thylakoid disks within receptors. (I believe that this transport is actually solitonic by virtue of the cholesterol molecules that are intercalated into the lipid membrane)
This “coherent time lag” or short term memory would seem to be the analogue of the “Memristor” effect that is being studied in the solid state – although in a different time domain. (I have discussed this development in a previous comment).
With the energy of the millions of single quantized events on the retinal surface coherently thermalized, the final step in the image formation process is the formation of a quantized electron particle at each site. This event is effected by the isomerization of the retinal molecule structurally contained within each “rhodopsin cage” complex. It is the electron particle that initiates subsequent biochemical processes in the biological system.
(Consistent with this explanation of events: a.), it has been experimentally shown that the retinal molecule is dicroically oriented to accept energy orthogonally to the direction of incident light, and b.) isomerization of the retinal molecule has long been known to occur in femtosecond (10-15 second) time.)
One then envisions a “coherent array of electronic signals existing with a time resolution of femtoseconds”.
Again, I would remind that this entire sequence of events is occurring at the plane of retinal receptor outer segments. The initial formation of the visual image occurs in very fast (femtosecond or less) time (and, in spaces that are within the near field of the light wave). It is the phononic “Memristor” function is what “translates the scene into the slow time domain of the human nervous system.
Speculation – might it be that the (slow) chemical processes used to explain the brain as an assemblage of neuronal connections be acting in a similar manner, i.e., “slowing down” some other, as yet unrecognized, high speed (quantum) process interacting with the brain?