On Standing Waves in Retinal Receptors and the Frequency of Light

by Gerald Huth on October 26, 2007

Harris writes that standing waves may form as a result of light reflection within the retinal receptors themselves and that the period of these waves will be associated with the wavelength of the interaction. He notes that this idea seems to have been around as early as 1867 in the work of Zenker.and others. I had not been aware of this idea but the essence, seems to have been that this light interaction within receptors was proposed as the source of color vision. Each cone or rod (quoting Harris) “can be modeled as a dimensionally tuned cavity, resonant at a specific color wavelength”. He presents a tutorial on how standing waves form for those not acquainted with this subject.

This is an illuminating (!) line of thought but not, I think, in the direction that Harris is leading! First and of significance, the approach treats light as a wave and not as “photons interacting with pigments, etc that leads in vision science to the ridiculous “photon catch” hypothesis that has been used in vision science to explain receptor length, It is abundantly clear from my simple geometrical approach that the retina fundamentally evolved to detect light as a wave. So in that we agree. My proposal posits, however, that light waves interact in the geometrically defined spaces between and not within the body of the retinal receptors themselves. It follows then this energy is transduced at the wave nodal points along the length of the receptor laterally into the receptor body with this body acting, again in my view, as an electron quantum confinement region, i.e., a space in the realm of quantum physics (see below for comments regarding the dichroic orientation of rhodopsin/retinal centers that supports my explanation).

I would propose then that the standing waves (or their quantized counterparts) that Harris posits are formed in this region – that the quantized electron wave that constitutes the absorbing mass is associated with standing waves? In essence then, Harris’ standing waves are created exactly where I feel they should be.

Moreover, the time domain of the proposed standing waves associated as they are with the frequency of light would seem to be consistent in explaining an interaction within this region.

This is wonderful!

In my latest Comments I have been exploring the extraordinary, and as yet unexplained, ability of the vision process to detect single photons (or “quanta”). I have put forward the thought that to explain this the retina must be considered as an array of individual light detection sites that operate in realm of quantum physics, i.e. of sub-micron spatial dimensions and temporally of the order of at least femtoseconds (or 10-15 seconds). A correspondent has noted that the measured signal-producing isomerization of the retinal molecule occurs in this very fast time do main (ref).

The following is a drawing made a long time ago (in 2001) by my son and I attempting to portray the, what we believed to be, unique ability of the retinal devices that we propose (“individual light detection centers comprising two adjacent receptors and the intervening space) to discern the direction of incident light (and in so doing satisfy the Fourier equation). We assumed that the length of each receptor acted as an electric giant dipole producing a differential analogue signal that encoded light direction.

Diagramatic Rod/Rod

Assuming that high frequency standing waves exist, it is possible that the system uses these waves to parse the absorbed wave at optical frequencies - a mechanism that would effectively digitize the differential signal at the point of retinal receptor detection. The extreme difficulty of measurement in this very high frequency range as noted by Harris would have precluded noticing this until now.

I have noted that future understanding of the vision process will require quantum thought. Perhaps this is the beginning of that process.

ADDED IN SUPPORT OF MY EXPLANATION (written a long time ago!)

Reading “Light Antennas in Phototactic Algae” by Foster and Smyth (Microbiological Reviews, Dec.1980, pp 572-630). An interesting paper that treats light as a classical wave used to analyze the ability of various algae specie to orient themselves towards the direction of incident light. They note on p 584:

‘Dichroism also occurs in the rhodopsin membranes of vertebrate photoreceptors and contributes significantly to their absorption. In these membranes, the transition moments of the rhodopsin molecules lie approximately parallel to the plane of the membrane and are randomly oriented within the plane (ref)’ Italics are mine./ GCH

Why would this be so if the traditional view of retinal light interaction were true, namely that photons are supposed to be incident parallel to the axis of receptor? Wouldn’t this transition moment be oriented in that direction instead of orthogonal to it?

I note that the traditional explanation for photon absorption is followed by the notion of a “photon catch” hypothesis where the function of the ‘coin stack’ of membraneous thylakoid disks within the receptor (with their illogical orthogonally-oriented transition moments!) is supposed to serve a statistical function – to ‘catch’ photons!

The reason for the orthogonal orientation of rhodopsin is explained by, and is consistent with, my explanation for light interaction. Light interacts as a wave between receptors imparting energy along their length (probably via evanescent wave phenomena) to effect a directional logic function. The stack of rhodopsin membrane have a specific defined function!”

GCH

10/26/07

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John Bisbocci November 4, 2007 at 9:41 am

As one who tries his best to explain scientific topics and ideas to young people ages 8-24, I need your help. Please correct me if I am wrong in thinking:
1. Light can be considered to be an invisible form of electromagnetic waves traveling in straight lines at the constant speed (velocity)of light.
2. Light can be considered to be a flow of “particles” called photons which are invisibe “packets” of energy moving in straight lines at the constant velocity of light.
3. In both models the operative word is invisible. Thus there is no such thing as visible light. One cannot see light of any wavelength or energy. Visible light is a misnomer. It’s not light we can see but rather light that can be “perceived” by our eyes.
4. This can be demonstrated using a penlight laser. The light cannot be seen as it travels across the room. Its pathway can be detected using smoke or powder that interacts with the light.
5. We can “see” material things (sense the presence of things) when light interacts with the thing in its path. Too, we can see material things when they themselves emit light. We can “see” the transmitter and/or the receiver but not the light.
I hope this is enough for you to grasp the confusion with the word visible with young people. How would you respond?
Thanks for your response.
John

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