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
Effects Of Electromagnetic Radiation On Visual Processing
Funder
National Health and Medical Research Council
Funding Amount
$299,564.00
Summary
We are increasingly surrounded by devices such as mobile phones and wireless networks. The effect of this electromagnetic radiation on human physiology is still largely unknown. Recent research has shown increases in "alpha-wave" electrical activity in the human brain after exposure to mobile phone radiation, but no effect has yet been shown on human mental processes. We plan to explore the effects of the electromagnetic environment on human visual processing, using sensitive techniques that wil ....We are increasingly surrounded by devices such as mobile phones and wireless networks. The effect of this electromagnetic radiation on human physiology is still largely unknown. Recent research has shown increases in "alpha-wave" electrical activity in the human brain after exposure to mobile phone radiation, but no effect has yet been shown on human mental processes. We plan to explore the effects of the electromagnetic environment on human visual processing, using sensitive techniques that will help reveal the underlying brain processes.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
Characterising The Changes In Regulation Of Visual Contrast Sensitivity In Glaucoma.
Funder
National Health and Medical Research Council
Funding Amount
$337,600.00
Summary
Glaucoma is the second leading cause of blindness in developed nations. A recent study estimated the number of Australian's that will need regular visual examination in 2030 either because they have glaucoma or glaucomatous risk factors to be at least 800,000. As the ultimate aim of glaucoma treatment is to maintain vision, visual functional assessment is of paramount importance to glaucoma management . The current standard measure for the assessment of visual loss due to glaucoma is visual fiel ....Glaucoma is the second leading cause of blindness in developed nations. A recent study estimated the number of Australian's that will need regular visual examination in 2030 either because they have glaucoma or glaucomatous risk factors to be at least 800,000. As the ultimate aim of glaucoma treatment is to maintain vision, visual functional assessment is of paramount importance to glaucoma management . The current standard measure for the assessment of visual loss due to glaucoma is visual field testing. Regrettably, substantial damage to retinal ganglion cells (the primary neurons affected by glaucoma) is often present prior to the discovery of visual field loss using standard measures. Indeed studies have demonstrated that even 30-50% retinal ganglion cell loss may only manifest as a mild visual field deficit using current standard testing. This project will use novel techniques for exploring sight impairment in glaucoma, enabling a better understanding of the underlying neural damage. Our pilot work demonstrates that these methods can detect loss of sight in areas diagnosed as normal using standard visual field testing. The study will provide new technologies for the assessment of early vision loss due to glaucoma that may enable the detection of malfunction of retinal ganglion cells prior to their death. Such measures of neural malfunction are essential to establishing the efficacy of new pharmacological therapies (known as neuroprotective agents) for glaucoma aimed at keeping retinal ganglion cells alive and functioning. This project also has the potential to identify visual measures that have better capability for monitoring the progression of vision loss due to glaucoma. Early detection of glaucoma and its progression is essential so that treatment can be initiated or altered, slowing the progression of vision loss and its toll on both the individual and the community.Read moreRead less