Areas Where Work Needs To Be Done And Correlations Made To Validate This Concept
May 4th, 2004 | No Comments »
As I have understood the Retinex theory that Land and his colleagues developed following his color vision experiments, it is a (complicated) algorithmic approach that attempts to simulate externally what Land theorized (correctly) was happening within the eye (the fulcrum, etc.). Land was constrained to this approach because he had only the “standard model” of light interaction with the retina and the resulting vision process to consider and this model could not be reconciled with his experimental results. This geometric approach, however, now presents the possibility of developing a precise mathematical understanding of vision predicated on knowledge of the mechanisms actually occurring within the eye. I would like to collaborate with anyone interested in such an effort.
I have arbitrarily assumed that the geometrically determined wavelengths absorbed by the retina that form the limits of the visible band correspond to the generally accepted values, i.e., 400 and 700 nm. It is axiomatic in this concept that whatever these values turn out to be they will be exact (”narrowly tuned”) determined by the geometric center-to-center distance between receptors. It occurs to me that these distances may vary mediated by genetic differences between individuals. For example, slightly smaller diameter rod receptors in an individual would mean that wavelengths shorter than 400 nm would be absorbed. This would mean that this individual would absorb into the damaging UVA radiation region (< 400 nm) and render that individual more at risk for AMD... or susceptibility to suntan? Have rod receptors of individuals raised in sunny latitudes evolved to be larger to protect from sunlight? Many questions?
Preliminary...but I am thinking about the meaning of this concept to the external scene that the eye perceives..... if the retinal surface is a Fourier surface (or simply, the "focal" plane of the eye) as the concept proposes (proves!) then the factor of time or simultaneity of light rqys arriving at the retina must be involved. It is axiomatic in a condensing lens system such as the eye that light rays reaching the fovea arrive simultaneously (I have termed this the "negation" of time because I believe that this idea will lead somewhere). This must be the basis for the intensity of perceived light. In this concept the fovea detects solely at the long wavelength limit and as an optical transform demonstrates , codes for the "outline sketch" of what is perceived. It then should follow that the "lines" ( or "edges" ) in such a sketch would result from light reflected from some object in the scene that was equidistant from the eye, i.e.,possessing the requirement that the time of flight of light rays emanating from that feature would arrive simultaneously at the fovea.... thus by virtue of increased intensity delineatring the feature. More...
I suggest that more computer simulations be done to demonstrate the fundamental relationship central to this concept between the refractive properties of the body and structure of the eye and the well characterized arrangement of cones and rods on the retinal surface. I did a number of preliminary simulations using Optical Research Associate’s “Light Tools” software but more needs to be done. It is abundantly clear using the dimensions and refractive properties of the components of the eye that these two factors are related…but more precise simulations need to be done.
The fundamental wavelength to which the retina of any specie is sensitive will be determined generally by the diameter of receptor or receptors that form the retina. Larger diameter receptors implying greater center-to-center distance will absorb at longer wavelengths. I have shown that this seems to be true for fish species whose visible range is known to lie beyond the red limit of humans into the near infrared. A number of papers attest that cones of fish retina are seven microns in diameter - 6 to 7 times larger than the human variety. Similar correlation seems evident for insects whose visual range extends into the ultraviolet. Insect receptors should be smaller than human… I found one pre-published reference that this is the case. More references?
The curious “dual-cone” morphology of trout (and other fish species?) retina? The purpose of such an adpatation might be, using this hypothesis, to detect some aspect of polarized light in the water environment. Orientation of such dual-cones?
More correlations are necessary. I have found it very difficult to obtain references to the retinal morphology of other species. Any help……?
If two sizes of receptors are present as the cones and rods of the human retina then the bandwidth (the “visual range”) of the vision process will correspond to the ratio of the diameters of the two types of receptors. This ratio (cone to rod) for human retinal receptors is 1.8:1 which corresponds to the visual band from 700 to 400 nanometers. Can any such correlations be made for other species whose visual characteristics are known?
The sensation of color will be present only if two sizes of receptors form the retina. Again, are any correlations possible for other species who have demonstrated the ability to sense color?
I have always claimed that the most glaring instance of a correlation that might be made involves wavelength interaction with the grana and stroma of the chloroplast organelle of green plants. In this concept the long wavelength interaction should be centered at stromal centers and short wavelengths interacting with grana. It has always seemed to me that such measurement was possible using modern confocal microscopy…but seems not to have been made.. with the mental construction that “photons interact…”.
I have had no success in interesting any biologist interested in the study of chloroplasts in making such a measurement although it seems technically possible using modern confocal optical microscopy.
I believe that there should be a broad correlation between the nanostructural morphology of photosynthesizing plants and algae and their spectral response to visible radiation. An effort should be undrtaken to find corellations between these factors.
The octagonal symmetry (eight rods fitting around each cone) that forms exact mid-band response in this concept seems surprisingly to be present in the retina of most (perhaps all) species …see Snyder’s work. I have proposed a possible connection with epitrochoidal figures (see an early entry under “Additional Thoughts”) where only such octagonal symmetry leads to an epitrochoid that has symmetric indentations (on both sides). The hexagonal symmetry of the all-cone and all-rod regions form epitrochoids that do not display symmetry having an indentation on only one side. Thus, is traversing the visible spectrum from red to blue spatial symmetry is only displayed at exact mid-band. Curious?
A note..Snyder’s review of the retinal architecture of many species reveals that each has two sizes of receptors… thus they may have some sensation of color.
Generation of an epitrochoid assumes that something “revolves around” a central something. This may involve the polarization of light sensed by the eye.
What might be the purpose of the conical shape of cones? I have offered two possible reasons. The first might be straightforward geometric “broad banding” in the antenna sense to detect a broader range of wavelengths near the long wavelength (red) limit. Alternatively, the cone shape may be desirable to broaden the direction sensing ability of the detecting element (formed by two adjacent cones). It would seem that this latter capability might be necessary considering the broad range of angles that the small area of the fovea must detect. Both scenarios involve geometry…geometry!!!
