Orientation-specific Contextual Modulation In Human Visual Cortex
Funder
National Health and Medical Research Council
Funding Amount
$290,413.00
Summary
Context has a strong infuence on our visual perception. We will study patterns of activity in the normal human brain to identify the cortical signature of contextual modulation in vision. The correspondences between patterns of brain activity and visual perception in the normal human brain will provide data against which brain activity in disorders such as schizophrenia and bipolar disorder can be assessed.
Combining input from vision and hearing greatly enhances perception when information from one of these senses is degraded or incomplete, such as when tracking objects in foggy, dark or noisy places. This enhancement is of considerable importance because degraded input is the daily situation faced by many people with hearing or vision impairment. We will study the neural processes underlying our ability to combine vision and hearing to create a more reliable and accurate perception of the world.
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
The human brain has many subdivisions (�areas�) that are dedicated to vision, but in many cases their functions remain unclear. This project will study an area located deep in the brain, about which very little is known, and which appears to be affected from early stages in conditions such as Alzheimer�s disease. By understanding the patterns of electrical activity of cells in this region, and their connections with other brain areas, we hope to decipher their contribution to sensory cognition.
In the areas of the brain where visual information is processed, cells respond to the presentation of visual stimuli by changing their pattern of electrical activity. At the first level of analysis, the primary visual cortex (V1), individual cells become active only if line segments or borders of a particular orientation are present in their field of detection, which encompasses a small part of the visual scene. Cells in other visual cortical areas (the extrastriate cortex) perform more complex ....In the areas of the brain where visual information is processed, cells respond to the presentation of visual stimuli by changing their pattern of electrical activity. At the first level of analysis, the primary visual cortex (V1), individual cells become active only if line segments or borders of a particular orientation are present in their field of detection, which encompasses a small part of the visual scene. Cells in other visual cortical areas (the extrastriate cortex) perform more complex detection tasks in comparison with those in V1, which demand integration of information coming from much larger portions of the visual scene. One example of these more complex properties is the phenomenon of long-range contour integration, where our visual system groups individual line segments having similar orientations, so that they are perceived as part of the same contour. This property is reflected in the electrical responses of cells in the dorsomedial visual area (DM). How are properties such as orientation specificity and long-range contour integration created? To begin addressing this question, we will investigate correlations between the physiological properties of identified cells, the spatial distribution of their information collecting regions (dendrites), and the anatomical pathways by which they receive information from other parts of the brain. This is a basic science study aimed at determining the extent to which the anatomical structure of the brain helps define the function of individual cells and brain areas. Its primary benefit will be to increase our understanding of the mechanisms underlying all sensory processing in the brain. The knowledge obtained may also lead to developments in areas of applied research including medicine and cognitive science (for example, understanding how the brain learns to interpret visual information in early life, and how visual processing degrades with ageing).Read moreRead less
A Functional Predictive Test For Age-related Macular Degeneration
Funder
National Health and Medical Research Council
Funding Amount
$532,500.00
Summary
Age-related macular degeneration (AMD) is the leading cause of blindness in our community. It is a progressive, late onset disease affecting central vision. Signs of disease are present in 15% of the population over 50 years with severe visual loss affecting increasing numbers in each subsequent decade. By 90 years 25% of people will have lost significant vision. There is no prevention, and treatment options are limited and have little impact on the rates of blindness. AMD causes enormous person ....Age-related macular degeneration (AMD) is the leading cause of blindness in our community. It is a progressive, late onset disease affecting central vision. Signs of disease are present in 15% of the population over 50 years with severe visual loss affecting increasing numbers in each subsequent decade. By 90 years 25% of people will have lost significant vision. There is no prevention, and treatment options are limited and have little impact on the rates of blindness. AMD causes enormous personal costs and places a massive burden on health resources. The high prevalence, anticipated increase in the ageing population and the limited treatment options, highlight the urgency with which research is required. The early clinical signs of AMD are yellow deposits called drusen, in the central retina (macula) and alteration in retinal pigmentation. As AMD progresses the macula is damaged either through atrophy (holes) or by growth of blood vessels. Currently, clinically accessible information about drusen and pigmentary changes are used to grade the severity of disease and predict the risk of progression to vision loss. This at risk group is recruited into prevention and intervention studies looking for new interventions. Such scoring of clinical characteristics currently underpins all clinical trials and epidemiological research in AMD. However this scheme is not without limitations, and results in an inexact correlation between clinical appearance and risk of blindness. We believe that a test of retinal function, (ability to see in the dark, to detect a faint light), will provide a better correlation for identifying patients at high risk of vision loss. We aim to test various aspects of retinal function (in both the light and dark and for moving and stationary objects) in subjects with early clinical signs of AMD, to identify parameters that will be more sensitive and specific predictors of risk of progression to visually devastating complications of AMD.Read moreRead less