The Experts below are selected from a list of 258 Experts worldwide ranked by ideXlab platform
Gerald H. Jacobs - One of the best experts on this subject based on the ideXlab platform.
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Genetics and Evolution of Color Vision in Primates
Oxford Research Encyclopedia of Neuroscience, 2019Co-Authors: Gerald H. JacobsAbstract:Color is a central feature of human perceptual experience where it functions as a critical component in the detection, identification, evaluation, placement, and appreciation of objects in the visual world. Its role is significantly enhanced by the fact that humans evolved a dimension of Color Vision beyond that available to most other mammals. Many fellow primates followed a similar path and in recent years the basic mechanisms that support Color Vision—the opsin genes, photopigments, cone signals, and central processing—have been the subjects of hundreds of investigations. Because of the tight linkage between opsin gene structure and the spectral sensitivity of cone photopigments, it is possible to trace pathways along which Color Vision may have evolved in primates. In turn, such information allows the development of hypotheses about the nature of Color Vision and its utility in nonhuman primates. These hypotheses are being critically evaluated in field studies where primates solve visual problems in the presence of the full panoply of photic cues. The intent of this research is to determine which aspects of these cues are critically linked to Color Vision and how their presence facilitates, impedes, or fails to influence the solutions. These investigations are challenging undertakings and the emerging literature is replete with contradictory conclusions. But steady progress is being made and it appears that (a) some of the original ideas about there being a restricted number of tasks for which Color Vision might be optimally utilized by nonhuman primates (e. g., fruit harvest) were too simplistic and (b) depending on circumstances that can include both features of proximate visual stimuli (spectral cues, luminance cues, size cues, motion cues, overall light levels) and situational variables (social cues, developmental status, species-specific traits) the utilization of Color Vision by nonhuman primates is apt to be complex and varied.
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Evolution of Color Vision
Human Color Vision, 2016Co-Authors: Almut Kelber, Gerald H. JacobsAbstract:Research conducted in recent years has documented the widespread presence of various forms of Color Vision in species from across the animal kingdom, helped to develop an understanding of the basic biological mechanisms that underlie this sensory capacity, and provided some insights into the utility of Color Vision in the natural world. This chapter draws information from all these various sources to reveal what has been learned about the evolution of Color Vision. In doing so, we examine the extent and nature of animal Color Vision, describe various structural features of eyes and photoreceptors that condition Color Vision, look at photopigment opsin genes and their Color Vision concomitants, and comment on specific cases where progress has been made toward understanding the functional utility of Color Vision. Although results from a wide range of different species are considered, we focus particular attention on issues relevant to the evolution of vertebrate Color Vision.
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The Evolution of Vertebrate Color Vision
Advances in experimental medicine and biology, 2012Co-Authors: Gerald H. JacobsAbstract:Color Vision is conventionally defined as the ability of animals to reliably discriminate among objects and lights based solely on differences in their spectral properties. Although the nature of Color Vision varies widely in different animals, a large majority of all vertebrate species possess some Color Vision and that fact attests to the adaptive importance this capacity holds as a tool for analyzing the environment. In recent years dramatic advances have been made in our understanding of the nature of vertebrate Color Vision and of the evolution of the biological mechanisms underlying this capacity. In this chapter I review and comment on these advances.
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The evolution of Primate Color Vision.
Scientific American, 2009Co-Authors: Gerald H. Jacobs, Jeremy NathansAbstract:The article discusses the evolution of Color Vision in primates including human beings. The differences between the Color Vision of primates between the Vision of nonprimate mammals are discussed, noting the presence of trichromacy, which depends of three varieties of light-activated pigments located in the retina. INSETS: Two Kinds of Mammalian Color Vision;EVOLUTIONARY ADVANTAGE?;Two Designs for Primate Vision;Untitled.
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Primate Color Vision: a comparative perspective.
Visual neuroscience, 2008Co-Authors: Gerald H. JacobsAbstract:Thirty years ago virtually everything known about primate Color Vision derived from psychophysical studies of normal and Color-defective humans and from physiological investigations of the visual system of the macaque monkey, the most popular of human surrogates for this purpose. The years since have witnessed much progress toward the goal of understanding this remarkable feature of primate Vision. Among many advances, investigations focused on naturally occurring variations in Color Vision in a wide range of nonhuman primate species have proven to be particularly valuable. Results from such studies have been central to our expanding understanding of the interrelationships between opsin genes, cone photopigments, neural organization, and Color Vision. This work is also yielding valuable insights into the evolution of Color Vision.
Arno G. Motulsky - One of the best experts on this subject based on the ideXlab platform.
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Color Vision Defects
Emery and Rimoin's Principles and Practice of Medical Genetics, 2013Co-Authors: Samir S. Deeb, Arno G. MotulskyAbstract:The human retina contains two classes of photoreceptors, rods and cones. Rods are responsible for Vision in dim light, whereas cones mediate Vision in bright light and enable the perception of Color. Individuals with normal Color Vision have three types of cone photoreceptors; the short wave-sensitive or blue , middle wave-sensitive or green and long wave-sensitive or red cones. Individuals with severe Color Vision defects usually either have nonfunctional red (protanopes) or green (deuteranopes) cone photoreceptors. Such individuals have dichromatic rather than trichromatic Color Vision. Those with milder Color Vision defects usually have either their red or green cone photoreceptor pigments replaced by an anomalous pigment with altered spectral sensitivity. Such individuals, therefore, have protanomalous or deuteranomalous trichromatic Color Vision. A wide variation in the ability to discriminate between Colors exists among individuals with defective Color Vision. Subtle variation in Color perception also exists among individuals with normal Color Vision. Significant advances have been made during the last 25 years toward understanding the molecular and genetic bases of variation in both defective and normal Color Vision. In this chapter, genotype to phenotype relationships in normal Color Vision and in the various classes of defective Color Vision will be reviewed. Emphasis will be placed on redgreen Color Vision defects since they are by far the most common. Recent reviews on this topic have been published and are recommended for additional reading.
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Molecular genetics of human Color Vision.
Behavior genetics, 1996Co-Authors: Samir S. Deeb, Arno G. MotulskyAbstract:The significant advances in our understanding of Color Vision has been due to the convergence of information from behavioral and molecular genetic analyses. The molecular biology of the visual pigments; molecular genetic basis of variation in normal and abnormal Color Vision, and regulation of the genes at the LWS-MWS pigment gene locus are discussed.
Maija Mäntyjärvi - One of the best experts on this subject based on the ideXlab platform.
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Color Vision defects after central serous chorioretinopathy.
Retina (Philadelphia Pa.), 2000Co-Authors: Tarja H. Maaranen, Kaija Tuppurainen, Maija MäntyjärviAbstract:Purpose To reexamine patients diagnosed with central serous chorioretinopathy (CSC) during the 10-year period from 1987 to 1996 to identify remaining Color Vision defects in the eyes with normal visual acuity (VA). Methods Thirty-nine patients were found with normal VA of 20/20 (logMAR 0) or better 8 to 166 months (mean +/- SD, 58.8 +/- 41.2) after active CSC. Color Vision was examined with the Standard Pseudoisochromatic Plates part 2, Farnsworth-Munsell 100 hue test, and Color Vision Meter 712 anomaloscope. Results Of the CSC eyes, 26 (67%) had a Color Vision defect, most of them in the blue area. There was no correlation between the time since the active disease and the results on the Color Vision tests. Of the contralateral eyes, 19 (49%) also had a Color Vision defect. Conclusion In many patients some degree of Color Vision defect remains after CSC even if the VA has recovered to normal. The contralateral eye can also have a Color Vision defect. This has not been previously reported and might be due to earlier subclinical CSC.
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Changes of Color Vision in ocular hypertension
International Ophthalmology, 1994Co-Authors: Maija Mäntyjärvi, Kaija TuppurainenAbstract:Fifty-six ocular hypertension (OHT) patients were examined for 2–3 days in the Eye Clinic of Kuopio University Hospital. No glaucomatous changes were found. Twenty-seven of them were found to have several risk factors for developing glaucoma and medication was started. Twenty-nine of the patients did not show risk factors and had no medication. Color Vision was examined with the Farnsworth-Munsell 100 (FM 100) hue test and Besançon anomalometer, later Color Vision Meter 712 at the beginning of the study and 3 years later. None of the 56 patients showed any glaucomatous changes after 3 years of the study. In the treatment group, the FM 100 test showed significantly (paired t-test, p=0.004) improved error scores after 3 years. In the nontreatment group, 19 patients did not develop risk factors; they had no significant changes in the Color Vision results. In 10 patients of the non-treatment group, risk factors had developed with elevated intraocular pressure and medication was started for them after 3 years. Their Color Vision results in the blue anomalous quotient (AQ) of the anomalometer had significantly shifted to the blue part of the equation (paired t-test, p=0.04). The other Color Vision results had not changed significantly. The significantly improved FM 100 scores in the treatment group could mean, that the treatment has a beneficial effect for the OHT eyes at risk for developing glaucoma. The significant shifting of the blue AQ towards the blue part of the equation in the eyes with elevated pressure after 3 years could mean that minimal change in blue Color Vision measured by a blue anomaloscope might be a risk factor for glaucoma development.
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Color Vision in Stargardt's disease
International Ophthalmology, 1992Co-Authors: Maija Mäntyjärvi, Kaija TuppurainenAbstract:The Color Vision of nine patients aged from 13 to 52 years with Stargardt's disease was studied with the following tests: Standard Pseudoisochromatic Plates part 2 (SSP2), Farnsworth-Munsell 100 hue test (FM100), Nagel (red-green) anomaloscope and Besançon (blue) anomalometer. At the beginning of the disease, a very slight defect in red-green Color Vision could be demonstrated. Later, a distinct acquired red (pseudo-protanomalous) defect in the Nagel anomaloscope and an abnormal error score in the FM100 test were observed. In advanced stages, the red defect became stronger (scotopization) and the FM100 test showed a red-green axis. In the course of the disease, a blue defect with the SPP2 plates and with the Besançon anomalometer could also be found. The visual acuities of the patients had a significant correlation with the matching ranges of the Rayleigh equation and the Moreland equation. The duration of the disease did not show any correlation with the Color Vision tests.
Samir S. Deeb - One of the best experts on this subject based on the ideXlab platform.
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Color Vision Defects
Emery and Rimoin's Principles and Practice of Medical Genetics, 2013Co-Authors: Samir S. Deeb, Arno G. MotulskyAbstract:The human retina contains two classes of photoreceptors, rods and cones. Rods are responsible for Vision in dim light, whereas cones mediate Vision in bright light and enable the perception of Color. Individuals with normal Color Vision have three types of cone photoreceptors; the short wave-sensitive or blue , middle wave-sensitive or green and long wave-sensitive or red cones. Individuals with severe Color Vision defects usually either have nonfunctional red (protanopes) or green (deuteranopes) cone photoreceptors. Such individuals have dichromatic rather than trichromatic Color Vision. Those with milder Color Vision defects usually have either their red or green cone photoreceptor pigments replaced by an anomalous pigment with altered spectral sensitivity. Such individuals, therefore, have protanomalous or deuteranomalous trichromatic Color Vision. A wide variation in the ability to discriminate between Colors exists among individuals with defective Color Vision. Subtle variation in Color perception also exists among individuals with normal Color Vision. Significant advances have been made during the last 25 years toward understanding the molecular and genetic bases of variation in both defective and normal Color Vision. In this chapter, genotype to phenotype relationships in normal Color Vision and in the various classes of defective Color Vision will be reviewed. Emphasis will be placed on redgreen Color Vision defects since they are by far the most common. Recent reviews on this topic have been published and are recommended for additional reading.
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Genetics of Color Vision deficiencies.
Developments in ophthalmology, 2003Co-Authors: Samir S. Deeb, Susanne KohlAbstract:The normal X-chromosome-linked Color Vision gene array is composed of a single red pigment gene followed by one or more green pigment genes. The high degree of homology between these genes predisposed them to unequal recombination, leading to gene deletions or the formation of red-green hybrid genes that explain the majority of the common red-green Color Vision deficiencies. Gene expression studies suggest that only the two most proximal genes of the array are expressed in the retina. The severity of the Color Vision defect is roughly related to the difference in absorption maxima of the photopigments encoded by the first two genes of the array. A single amino acid polymorphism (Ser180Ala) in the red pigment accounts for the subtle difference in normal Color Vision and influences the severity of Color Vision deficiency. Blue cone monochromacy is a rare disorder that involves absence of red and green cone function. It is caused either by deletion of a critical region that regulates expression of the red/green gene array, or by mutations that inactivate the red and green pigment genes. Total Color blindness is another rare disease that involves complete absence of all cone function. A number of mutations in the genes encoding the cone-specific alpha- and beta-subunits of the cation channel and the alpha-subunit of transducin have been implicated in this disorder.
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Molecular genetics of human Color Vision.
Behavior genetics, 1996Co-Authors: Samir S. Deeb, Arno G. MotulskyAbstract:The significant advances in our understanding of Color Vision has been due to the convergence of information from behavioral and molecular genetic analyses. The molecular biology of the visual pigments; molecular genetic basis of variation in normal and abnormal Color Vision, and regulation of the genes at the LWS-MWS pigment gene locus are discussed.
Kaija Tuppurainen - One of the best experts on this subject based on the ideXlab platform.
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Color Vision defects after central serous chorioretinopathy.
Retina (Philadelphia Pa.), 2000Co-Authors: Tarja H. Maaranen, Kaija Tuppurainen, Maija MäntyjärviAbstract:Purpose To reexamine patients diagnosed with central serous chorioretinopathy (CSC) during the 10-year period from 1987 to 1996 to identify remaining Color Vision defects in the eyes with normal visual acuity (VA). Methods Thirty-nine patients were found with normal VA of 20/20 (logMAR 0) or better 8 to 166 months (mean +/- SD, 58.8 +/- 41.2) after active CSC. Color Vision was examined with the Standard Pseudoisochromatic Plates part 2, Farnsworth-Munsell 100 hue test, and Color Vision Meter 712 anomaloscope. Results Of the CSC eyes, 26 (67%) had a Color Vision defect, most of them in the blue area. There was no correlation between the time since the active disease and the results on the Color Vision tests. Of the contralateral eyes, 19 (49%) also had a Color Vision defect. Conclusion In many patients some degree of Color Vision defect remains after CSC even if the VA has recovered to normal. The contralateral eye can also have a Color Vision defect. This has not been previously reported and might be due to earlier subclinical CSC.
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Changes of Color Vision in ocular hypertension
International Ophthalmology, 1994Co-Authors: Maija Mäntyjärvi, Kaija TuppurainenAbstract:Fifty-six ocular hypertension (OHT) patients were examined for 2–3 days in the Eye Clinic of Kuopio University Hospital. No glaucomatous changes were found. Twenty-seven of them were found to have several risk factors for developing glaucoma and medication was started. Twenty-nine of the patients did not show risk factors and had no medication. Color Vision was examined with the Farnsworth-Munsell 100 (FM 100) hue test and Besançon anomalometer, later Color Vision Meter 712 at the beginning of the study and 3 years later. None of the 56 patients showed any glaucomatous changes after 3 years of the study. In the treatment group, the FM 100 test showed significantly (paired t-test, p=0.004) improved error scores after 3 years. In the nontreatment group, 19 patients did not develop risk factors; they had no significant changes in the Color Vision results. In 10 patients of the non-treatment group, risk factors had developed with elevated intraocular pressure and medication was started for them after 3 years. Their Color Vision results in the blue anomalous quotient (AQ) of the anomalometer had significantly shifted to the blue part of the equation (paired t-test, p=0.04). The other Color Vision results had not changed significantly. The significantly improved FM 100 scores in the treatment group could mean, that the treatment has a beneficial effect for the OHT eyes at risk for developing glaucoma. The significant shifting of the blue AQ towards the blue part of the equation in the eyes with elevated pressure after 3 years could mean that minimal change in blue Color Vision measured by a blue anomaloscope might be a risk factor for glaucoma development.
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Color Vision in Stargardt's disease
International Ophthalmology, 1992Co-Authors: Maija Mäntyjärvi, Kaija TuppurainenAbstract:The Color Vision of nine patients aged from 13 to 52 years with Stargardt's disease was studied with the following tests: Standard Pseudoisochromatic Plates part 2 (SSP2), Farnsworth-Munsell 100 hue test (FM100), Nagel (red-green) anomaloscope and Besançon (blue) anomalometer. At the beginning of the disease, a very slight defect in red-green Color Vision could be demonstrated. Later, a distinct acquired red (pseudo-protanomalous) defect in the Nagel anomaloscope and an abnormal error score in the FM100 test were observed. In advanced stages, the red defect became stronger (scotopization) and the FM100 test showed a red-green axis. In the course of the disease, a blue defect with the SPP2 plates and with the Besançon anomalometer could also be found. The visual acuities of the patients had a significant correlation with the matching ranges of the Rayleigh equation and the Moreland equation. The duration of the disease did not show any correlation with the Color Vision tests.