The Signals Of Nerve Cells That Provide The Capacity For Sight
Funder
National Health and Medical Research Council
Funding Amount
$385,115.00
Summary
Sight relies on the signals of nerve cells in the brain, but we know little about the way in which nerve cells support this, or why in some people sight is diminished. In this work we will measure the signals of nerve cells in the visual pathway to gain knowledge of these processes: we will make measurements in normal animals and in those that suffer from brain disorders. Our work will provide a scientific basis for the diagnosis and treatment of these disorders.
Headache Prophylaxis By Cortico-brainstem Mechanisms
Funder
National Health and Medical Research Council
Funding Amount
$616,437.00
Summary
In this project we hope to discover the cause of migraine headache. Many triggers lead to migraine, but we do not know how. We believe the triggers produce a defect in pain control by the brainstem, which normally keeps sensation from the head below the pain threshold. In migraine, trigger factors acting high in the brain open a pain control gate lower in the brain, producing a migraine headache. If we can prove this, we can develop therapies that will prevent migraine before it starts.
Structure And Function Of The Third Geniculocortical Pathway In Primates.
Funder
National Health and Medical Research Council
Funding Amount
$296,777.00
Summary
Our understanding of the human visual system has been based on the idea that there are two main nerve pathways from the eye to the brain. One, called the parvocellular pathway, is for colour and detail vision, and the other, called the magnocellular pathway, is for movement perception. Damage to either pathway by disease such as glaucoma, or a lesion such as stroke, will cause specific changes in visual perception and these changes can be used to diagnose the nature of the disease or lesion. We ....Our understanding of the human visual system has been based on the idea that there are two main nerve pathways from the eye to the brain. One, called the parvocellular pathway, is for colour and detail vision, and the other, called the magnocellular pathway, is for movement perception. Damage to either pathway by disease such as glaucoma, or a lesion such as stroke, will cause specific changes in visual perception and these changes can be used to diagnose the nature of the disease or lesion. We will study a recently recognised third subdivision of the visual pathway, called the koniocellular pathway. The properties of koniocellular cells have not previously been studied in anthropoid primates, and their importance for human vision is not well understood. We will study the way that koniocellular cells respond to moving and patterned stimuli, and their connections with the cerebral cortex, in order to determine whether this pathway could contribute to aspects of normal and abnormal visual perception. We will follow up our preliminary evidence that koniocellular cells respond to visual stimuli of the type used to diagnose the early stages of eye diseases such as glaucoma. The results will give us a better understanding of the way that the nervous system processes visual information, and will clarify the basis of disturbances to normal visual function.Read moreRead less
Temporal Processing In The Superior Olivary Complex: Impact Of Deafness And Peripheral Electrical Stimulation Strategies
Funder
National Health and Medical Research Council
Funding Amount
$225,500.00
Summary
The brain can use timing or temporal information to extract the frequency and location of sound. Timing information is coded by the pattern of responses of brain cells that match the period of the sound wave. These responses can be measured as small voltage spikes or action potentials. Integration of these responses from one brain-processing site to another relies on precise (temporally matched) firing among a population of cells that are activated in response to sound. Sound localisation relies ....The brain can use timing or temporal information to extract the frequency and location of sound. Timing information is coded by the pattern of responses of brain cells that match the period of the sound wave. These responses can be measured as small voltage spikes or action potentials. Integration of these responses from one brain-processing site to another relies on precise (temporally matched) firing among a population of cells that are activated in response to sound. Sound localisation relies on this temporal integration from information coming from both ears. Specifically, the integration of this information relies on the balance of incoming inputs from both ears, which maintains an appropriate time window depending on the location of sound in space. Recent evidence suggests that in deafness this process of integration is disrupted which may be possibly due to an inability to regulate the coherent activation of cells. This has implications for cochlear implant users whose ability to process temporal information is compromised by a loss of temporal coding ability resulting from prior deafness. In this project we will measure voltage changes occurring inside cells of the superior olivary complex, which contains a group of structures that integrate input from both ears. We will examine the ability of these cells to process temporal information in normal and deafened conditions. This study will lead not only to an understanding of basic mechanisms for auditory coding but also to improved electrical stimulation strategies for patients with cochlear implants.Read moreRead less
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
Non-standard Receptive Fields In The Primate Visual System
Funder
National Health and Medical Research Council
Funding Amount
$392,983.00
Summary
We recently discovered that an evolutionary ancient brain pathway transmits visual signals for blue-yellow colour vision. We now plan to discover whether this pathway could also contribute to form and movement perception, and to visual functions (called blindsight) that survive damage to the main visual area of the brain. This project will contribute to understanding the effects of damage to visual pathways following stroke or brain injury, as well as to understanding normal visual function.