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Results for “COLOR BLINDNESS”

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PubMed2005

Elephants and human color-blind deuteranopes have identical sets of visual pigments.

Being the largest land mammals, elephants have very few natural enemies and are active during both day and night. Compared with those of diurnal and nocturnal animals, the eyes of elephants and other arrhythmic species, such as many ungulates and large carnivores, must function in both the bright light of day and dim light of night. Despite their fundamental importance, the roles of photosensitive molecules, visual pigments, in arrhythmic vision are not well understood. Here we report that elephants (Loxodonta africana and Elephas maximus) use RH1, SWS1, and LWS pigments, which are maximally sensitive to 496, 419, and 552 nm, respectively. These light sensitivities are virtually identical to those of certain "color-blind" people who lack MWS pigments, which are maximally sensitive to 530 nm. During the day, therefore, elephants seem to have the dichromatic color vision of deuteranopes. During the night, however, they are likely to use RH1 and SWS1 pigments and detect light at 420-490 nm.

Animals↗
PubMed1998

Complete sparing of high-contrast color input to motion perception in cortical color blindness.

It is widely held that color and motion are processed by separate parallel pathways in the visual system, but this view is difficult to reconcile with the fact that motion can be detected in equiluminant stimuli that are defined by color alone. To examine the relationship between color and motion, we tested three patients who had lost their color vision following cortical damage (central achromatopsia). Despite their profound loss in the subjective experience of color and their inability to detect the motion of faint colors, all three subjects showed surprisingly strong responses to high-contrast, moving color stimuli--equal in all respects to the performance of subjects with normal color vision. The pathway from opponent-color detectors in the retina to the motion analysis areas must therefore be independent of the damaged color centers in the occipitotemporal area. It is probably also independent of the motion analysis area MT/V5, because the contribution of color to motion detection in these patients is much stronger than the color response of monkey area MT.

Adult↗
PubMed1991

[The molecular genetics of color blindness].

The gene structures of three color pigments have been reported by Nathans et al. in 1985. One copy of red gene and 1 to 3 copies of green genes are tandemly repeated on X chromosome. As the structures of red and green genes are highly homologous (96%) and tandemly repeated, they cross-over on chromosome during meiosis and hybrid genes were produced. The function of these hybrid genes exhibits abnormal spectrum for red and green light. The 5' portion of the gene determines which cone cell type express the gene and the 3' portion of the gene determines the type of spectrum. In the 3' portion, exon 4 are associated with a small shift of spectrum and exon 5 determines a large shift of spectrum. For example, a hybrid gene with 5' region of red and 3' region of green is expressed in the red cones and exhibits green spectrum. Abnormality of color perception depends on the hybrid ratio of red and green genes.

Base Sequence↗