Origin And Specificity Of Neuronal Signals For Colour Vision In Primates.
Funder
National Health and Medical Research Council
Funding Amount
$490,500.00
Summary
How do we see colours? What do colour blind people see? Although colour is one of the most important attributes of objects in the visual world, the way that colour is processed in the brain is poorly understood. The aim of this project is to study the way that nerve cells in the eye (the retina) and the visual part of the brain are specialised to transmit signals for colour perception. The visual system of humans and other primates includes nerve cells which are selective for a limited range of ....How do we see colours? What do colour blind people see? Although colour is one of the most important attributes of objects in the visual world, the way that colour is processed in the brain is poorly understood. The aim of this project is to study the way that nerve cells in the eye (the retina) and the visual part of the brain are specialised to transmit signals for colour perception. The visual system of humans and other primates includes nerve cells which are selective for a limited range of wavelengths reflected by objects in the visual world. We will study how this selectivity is generated, by examining how the colour receptors are connected within the retina to the cells which transmit nerve impulses to the brain. Between 5 and 7 percent of male humans have colour vision defects. Many objects which appear clearly different to colour-normal observers cannot be discriminated by colour-defective observers, and entry to professions such as the police and airline industry is restricted for individuals with colour vision defects. We will study the basis of reduced colour perception ability in red-green colour blindness. This will be done by measuring the responses of nerve cells in a species of primate (marmoset) in which many animals have colour vision receptors resembling those of humans with colour vision defects. We will measure the reliability with which individual neurones can transmit signals for colour vision when they receive input from such abnormal receptors. It is known that nerve cells transmit their message within the brain by means of brief electrical impulses called action potentials. In addition to studying the basis of human colour discrimination, the project also addresses one of the fundamental questions of sensory processing, by studying the reliability of the coded message carried by action potentials within the central nervous system.Read moreRead less
Functional Analysis Of Human MC1R Polymorphisms In Directing Melanocyte Phenotype
Funder
National Health and Medical Research Council
Funding Amount
$361,527.00
Summary
Sunsmart campaigns are a unifying element in the lives of many Australians who wish to ensure protection against the damaging effects of ultraviolet rays in sunlight. Indeed, Australians have the highest incidence of UV-induced melanoma in the world. Although it is evident that lighter skin colours are more susceptible to sun damage, the relationship between sun exposure, skin type and melanoma formation is less clear. An essential first step in understanding the complex interactions that give r ....Sunsmart campaigns are a unifying element in the lives of many Australians who wish to ensure protection against the damaging effects of ultraviolet rays in sunlight. Indeed, Australians have the highest incidence of UV-induced melanoma in the world. Although it is evident that lighter skin colours are more susceptible to sun damage, the relationship between sun exposure, skin type and melanoma formation is less clear. An essential first step in understanding the complex interactions that give rise to melanoma, and in identifying individuals that have a high susceptibility, is to reduce phenotypic analyses to genotypic classifications. As pigmentation phenotype is a factor of central importance in determining an individuals risk for melanoma, characterisation of the genes underlying the physical qualities of human eye, hair and skin colour will give a more direct and accurate genotypic assessment of risk. Results from an epidemiology study of melanoma patients in Queensland have identified a number of genetic changes within the melanocyte stimulating hormone receptor (MC1R) gene that associate with skin, hair and eye colour as well as with incidence of melanoma. Further investigation of MC1R gene alleles which segregate with skin and hair colours will provide the beginning for a whole new genotype-based classification of skin colour and melanoma risk, and will significantly contribute to our understanding of what makes some individuals highly susceptible to melanoma while others are not. Indeed, MC1R polymorphisms may numerically be the most important melanoma predisposition gene yet identified, exerting its effects as one of those common genes of small effect which may account for much more of the case load in melanoma than rarer genes of large effect. Studies such as this will enable powerful genotyping methods to be employed in identification of those individuals at highest risk for melanoma and other skin cancers.Read moreRead less
Network Properties Of Colour Pathways In Primates.
Funder
National Health and Medical Research Council
Funding Amount
$594,891.00
Summary
This project concerns the way in which the eye and brain work together, to enable perception of the colour, form, and movements of objects in the visual world. It is thought that these different attributes of the visual environment are signalled by several parallel nerve pathways in the visual system, but the nature of the neuronal code carried by these pathways remains poorly understood. The aim of our project is to address this basic question, in experimental studies of the intact primate visu ....This project concerns the way in which the eye and brain work together, to enable perception of the colour, form, and movements of objects in the visual world. It is thought that these different attributes of the visual environment are signalled by several parallel nerve pathways in the visual system, but the nature of the neuronal code carried by these pathways remains poorly understood. The aim of our project is to address this basic question, in experimental studies of the intact primate visual system. We plan two sets of experiments. Firstly, we will test the hypothesis that signals for both high-acuity form vision and red-green colour vision can be carried along a single neuronal pathway. We will determine whether response timing in nerve pathways provides a clue by which colour and brightness variation in the environment can be discriminated. Secondly, we will study the segregation of colour and acuity-related signals in the brain, using the method of functional optical imaging. This method, which allows nerve activity to be monitored at high resolution, over relatively large areas of the brain surface (cortex), will allow us test the hypothesis that colour signals are segregated to distinct regions of the visual cortex. These experiments address basic questions, but have application to human vision and visual dysfunction. Good acuity is essential for everyday tasks such as reading, and specific defects in colour vision are used for early detection of neurological dysfunction in diseases such as glaucoma and multiple sclerosis. Understanding the properties of neurons which underlie visual perception can thus help us to understand normal visual performance, and to develop better methods for detection and treatments for such disorders.Read moreRead less
Myopia And Colour Vision: Potential Impact Of Colour Vision Gene Variation On Susceptibility To Myopia
Funder
National Health and Medical Research Council
Funding Amount
$227,947.00
Summary
The frequency of myopia has shown a rapid increase in recent years but the underlying cause remains largely unknown. Our recent work on severe myopia with dichromacy has indicated that some forms of myopia may arise through changes in cone visual pigments and the arrangement of cone photoreceptors in the retina which impact on the feedback loop between image formation and eye elongation. This study seeks to explore this link in detail in myopia patients that possess normal colour vision.