Iodopsinum ( iodopsinum ; from other Greek. Ἰώδης - "similar to the color of violets " + other Greek. Ωπ глаз - eye) is the common name for several visual pigments of humans and some mammals . These pigments consist of a protein molecule bound to the retinal chromophore . Contained in the cones of the retina and provide color vision , unlike another visual pigment - rhodopsin , responsible for twilight vision .
Content
Types of iodopsins
| Cone type | Title | Range | Maximum Sensitivity [1] [2] |
|---|---|---|---|
| S ( OPN1SW ) - "tritan", "cyanolab" | β | 400-500 nm | 420-440 nm |
| M ( OPN1MW ) - "deitan", "chlorolab" | γ | 450-630 nm | 534-545 nm |
| L ( OPN1LW ) - "protan", "erythrolab" | ρ | 500-700 nm | 564-580 nm |
Research History
The first attempts to find three pigments and, as suggested by three types of cones (based on the assumptions of the three-component theory of vision that each cone contains only one pigment), were carried out by Rashton [3] , who perfected the densitometry technique for lifetime measurement of light absorption coefficients with different lengths waves in the layer of retinal photoreceptors. It was shown that dichromats lack one of the pigments that are found in trichromats and correspond to the red and green sensitive receivers of trichromat: erythrolab (maximum about 585 nm.) For protanope and chlorolab (maximum about 540 nm.) For deuteranope .
To detect the presence of the third (theoretically predicted blue-sensitive pigment) cyanolab, which (according to the three-component theory of color vision) is contained in the third "receiver", neither dichromats nor trichromats succeeded for a long time. They tried to explain this with yellow pigmentation in the region of the central fossa, which, according to researchers, “complicates” measurements at the blue end of the spectrum.
The next step in this direction was the study of photopigments contained in individual cones of humans [4] and macaques [5] . The sizes of the foveal cones are too small to be an object of study, and all the data obtained relate only to paraffeal cones. Each cone, at least extrafoveal, apparently contains only one of the pigments or mainly one of them. The question of the localization of pigments in foveal cones was not resolved at that time, and it was assumed that foveal cones contained a mixture of several pigments. [5] .
Study of the optical characteristics of iodopsin
Then came the work of Wald [7] . The use of an intense adaptive yellow, magenta, and blue background allowed Wald to obtain three different threshold curves. When adjusting for absorption in the anterior media of the eye (lens and yellow macular pigment), Wald calls the maxima of the three “receivers” (although he really did not detect the receivers, but only the absorption maxima by the retinal tissues) 430, 540 and 575 nm. [eight]
Links
- ↑ Wyszecki, Günther. Color Science: Concepts and Methods, Quantitative Data and Formulae. - 2nd. - New York: Wiley Series in Pure and Applied Optics, 1982. - ISBN 0-471-02106-7 .
- ↑ RWG Hunt. The Reproduction of Color. - 6th. - Chichester UK: Wiley – IS & T Series in Imaging Science and Technology, 2004. - P. 11–12. - ISBN 0-470-02425-9 .
- ↑ Rushton WAH 1958. In: Visual problems of color. NPL Sump. No 8, 1, Teddington: 73.
- ↑ Wald G., Brown PK, 1964. Science, 144: 45., Wald G., Brown PK, 1965. Cold Spring Harbor Symp., 30: 345
- ↑ 1 2 Marks WB, WH Dobelle, EF McNichol. 1964. Science, 143: 1181.
- ↑ Nyberg N. D., Yustova E. N. , 1955. Tr. Gos. opt. Inst. 24: 33.
- ↑ Wald G. 1964. Science, 144: 1007.
- ↑ USSR Academy of Sciences, Joint Scientific Council “Physiology of Man and Animals,” Physiology of Sensory Systems. Part 1. The physiology of vision. 1971, Publishing House "Science", Leningrad Branch. Ch. 11, Color Vision, Page 246—258