Electromagnetic Effects in Retinal Receptors

by Gerald Huth on February 10, 2006

Allan Snyder’s published work contains in my view some of the most important considerations and observations of the eye and vision process. It was from one of his papers that I learned that the same octagonal symmetry of rods-around-cones on the human retina is seemingly present in the visual organs of all species. (I consider this geometrical consideration important and it is discussed elsewhere in this work).

My thoughts from one of his papers: (A.W.Snyder, P.A.V.Hall, “Unification of Electromagnetic Effects in Human Retinal Receptors with Three Pigment Colour Vision”. Nature, Vol. 223, August 2,1969)

The general discussion of this paper centers on the physics of power absorbed in retinal pigments but the authors conclude:

“Spectrophotometric measurements measure the power….absorbed by the photosensitive material of the outer segments. Three P(lambda)s have been measured. It has been concluded from these experiments that three individual molecular substances …are present. Because, however, three photopigments have not been extracted from the human receptors, this conclusion is speculative in that it ignores the electromagnetic effects M(lambda)”. (bold text is mine).

(I would note here that my review of George Wald’s work revealed the same thing..Wald, after identifying the one chemical pigment specie (rhodopsin) searched diligently for the “other two” that he felt must be present…he could never find them!).

Further on on p.527:

“We conclude from the above discussion that there is no definitive evidence for three molecular substances mediating colour vision; however, it is established that three receptors (pigment responses as defined above) do exist”.

(The reader will have become aware that I conclude that the established three receptors are the three receptor appositions of the retina).

From the following paragraph:
“An alternative interpretation of the spectrophotometric experiments, which also provides an explanation for the difficulty of extracting three molecular photosensitive materials, follows from considering only one S(lambda) but three M(lambda)s produced by three types of receptors,….There are a number of convincing mechanisms by which this could occur; one possibility is that the identical molecular substance is arranged differently in each receptor type”.

(I must define the S and M terms used in the above: the power P absorbed by the pigment in the outer segment is the product of S and M where S is the “spectral absorption property of the pigment molecules independent of their physical arrangement and situation in the outer segment” and M is the “electromagnetic spectral property..a complex function of wavelength taking into account the spatial relationship between the molecules and the electromagnetic fields”. It thus seems clear that the model that I propose can be interpreted in the context of the above!).
S is the spectral property of pigment molecules that is usually, and solely, considered in vision science measurements. M, however, is the crucially important factor that determines how the pigment molecule is affected by it’s electromagnetic environment….and the essence of the concept proposed herein.

And, if one has any doubt that the rhodopsin complex is labile and thus able to rotate freely in an electromagnetic field, from Hargrave (“Molecular Dynamics of the Rod Cell”) p.218,
“The Disk Membrane Bilayer is Highly Fluid”, “..it became clear that proteins (referring to the photoreceptor rhodopsin proteins ) were able to freely rotate about their axis and to diffuse laterally within the plane of the lipid bilayer (ref)”. And later: “Fluidity of the disk membrane is equivalent to that of olive oil (ref)”.

Now.. Now……I realize that it will be argued that, subsequent to this work, “genetics has succeeded in identifying the three pigment species at issue”. But..please think!…following from my comments of the past few days…the species that have been genetically identified (and formulated) are simply three variations of the rhodopsin complex (each containing the same ubiquitous central retinal molecule) whose optical properties will be altered in the final environment in which they find themselves through the electromagnetic spectral property term M in the above.

The final optical response of pigment molecules depends on the specific electromagnetic field surrounding it and this, in the retina, is determined by nanostructural considerations.



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