NEURAL MODULATION OF HEARING LOSSES INDUCED BY LOUD SOUND
Funder
National Health and Medical Research Council
Funding Amount
$290,500.00
Summary
Loud sounds, from occupational and recreational sources, are the most common threat to hearing and can result in temporary hearing losses (as might be experienced after an evening at a noisy pub or concert) or permanent hearing losses (after prolonged or multiple loud sounds, as for example in a noisy work environment). Noise reduction programs are either not always possible or effectively applied. A parallel strategy is the study of biological mechanisms that may ameliorate hearing damage, with ....Loud sounds, from occupational and recreational sources, are the most common threat to hearing and can result in temporary hearing losses (as might be experienced after an evening at a noisy pub or concert) or permanent hearing losses (after prolonged or multiple loud sounds, as for example in a noisy work environment). Noise reduction programs are either not always possible or effectively applied. A parallel strategy is the study of biological mechanisms that may ameliorate hearing damage, with a view to optimising such mechanisms. I propose to build on seminal Australian work to examine how one such system, nerves from the brain to the inner ear (the site of most damage from loud sounds), modulates hearing losses caused by loud sounds. Early studies indicated these nerves could protect from damage induced by short-lasting loud sound and this has led to international interest in functional applications of such protection to reduce hearing damage suffered by humans. However, my recent work indicates the nerves exert complex protective and exacerbative effects to loud sounds similar to common trauma or occurring under conditions similar to common trauma. They even exacerbate hearing losses due to loud sound, especially when there is an imbalance in hearing sensitivity in the two ears (bilateral) similar to what is common in humans. These findings make it critical that functional application be delayed until the full range of effects exerted by the nerves is understood. I propose to elucidate the novel complex effects of these nerves to loud sound. Specific aims are: (1) To understand effects of these pathways to loud sounds like those encountered by humans, (2) To investigate how chronic imbalanced bilateral hearing sensitivity, like that common in humans, alters effects of the nerves and when they change from being protective to exacerbative, (3) To adduce how an atraumatic sound affects hearing losses due to later loud sound and the role played by these nerves.Read moreRead less
Development And Plasticity Of The Visual Cortex: An Anatomical And Functional Study
Funder
National Health and Medical Research Council
Funding Amount
$420,872.00
Summary
Much of the human brain is devoted to vision, which requires the integrated activity of many interconnected areas of the cerebral cortex. Damage to these areas is a relatively common complication of preterm delivery and- or perinatal conditions including trauma and infection. The aim of this project is to investigate the way in which the multiple visual areas of the brain develop and become 'wired' together, and determine how the brain can successfully compensate for damage to these areas.
Cochlear Mechanisms Of Otoacoustic Emission Generation
Funder
National Health and Medical Research Council
Funding Amount
$311,989.00
Summary
Deafness, both congenital and acquired, is likely to be one of the major causes of disability in the Australian workforce, in young Australians, and in some categories of pre-term infants in the next decade or two. While not life-threatening, hearing impairment deprives individuals of one of their most basic social needs: the ability to communicate with others. Although little can be done to recover lost hearing, it is important to detect hearing loss as early as possible in order to reduce furt ....Deafness, both congenital and acquired, is likely to be one of the major causes of disability in the Australian workforce, in young Australians, and in some categories of pre-term infants in the next decade or two. While not life-threatening, hearing impairment deprives individuals of one of their most basic social needs: the ability to communicate with others. Although little can be done to recover lost hearing, it is important to detect hearing loss as early as possible in order to reduce further loss (by behaviour modification in the case of noise-exposed adults) and to provide hearing assistance in very young children so that they may be exposed to some degree of auditory experience at as early an age as possible. To this end, the phenomenon of otoacoustic emissions, or noises from the ear, now recognised for twenty years, is likely to become even more significant in the early years of the next millennium. Otoacoustic emissions were first demonstrated as very soft echoes re-emerging from the ear after a delay of ten milliseconds or so following a click stimulus. These echoes are sounds produced by the ear as it goes about its normal function and are lost if the hearing sensitivity of the individual is below normal. Several other forms of otoacoustic emissions have been discovered and rapidly applied to the testing of hearing so that today the technique of assessing hearing status in neonates and others unable to co-operate, as well as in diagnostic applications, is widespread. The application of the technique, however, has preceded a real understanding of what otoacoustic emissions are and how they are generated, and their widespread use at the moment is somewhat akin to a car repair industry which does not understand how an engine works. This proposal intends to investigate the basic mechanisms behind otoacoustic emissions in order to improve their efficiency and accuracy of clinical interpretation.Read moreRead less
Interactions Of Gastric Hormones With Vagal Afferent Pathways And The Role Of This System In Obesity
Funder
National Health and Medical Research Council
Funding Amount
$550,918.00
Summary
When we feel full after a meal it is the result of a variety of different nerve signals from the gut in response to distension of the stomach and specific nutrients. These signals are disordered in obesity and this project aims to find out how to correct this problem in this modern day epidemic.
Extraction Of Key Features Of Natural Speech By Ventral Cochlear Nucleus Neurons
Funder
National Health and Medical Research Council
Funding Amount
$225,330.00
Summary
Little is known about how speech is processed and transformed by the central auditory pathway, and how the critical temporal and spectral features that identify a speech sound segment (a phoneme) are extracted. To date, most studies have approached this issue by using synthetic speech and examined the responses of the peripheral auditory nerve only. The aim of this study is to examine how important features of naturally-spoken speech are encoded by the cochlear nucleus (CN) - the first station i ....Little is known about how speech is processed and transformed by the central auditory pathway, and how the critical temporal and spectral features that identify a speech sound segment (a phoneme) are extracted. To date, most studies have approached this issue by using synthetic speech and examined the responses of the peripheral auditory nerve only. The aim of this study is to examine how important features of naturally-spoken speech are encoded by the cochlear nucleus (CN) - the first station in the auditory pathway located in the brainstem. The CN is a complex of different cell types that have the capacity to transmit, transform, and encode complex acoustic information in different ways. The proposed experiments involve recording the bioelectrical signal from single CN cells in anaesthetised rats while presenting naturally-spoken syllables, both in quiet and in the presence of noise. It is important to examine what happens to the neural responses in the latter condition, because all animals must cope with the problem of extracting important signals from background noise. While noise clearly interferes with the perception of another sound, the auditory system is in fact quite good at extracting signals in the presence of noise. This is well demonstrated by our ability to understand speech in the presence of quite high noise levels. This ability is severely degraded in the hearing impaired. Thus, one of the aims of this study is to examine the mechanisms and limits of the CN's ability to encode speech in a noisy background. A greater understanding of the mechanisms the nervous system uses to extract critical features of speech will not only build on our knowledge of auditory brainstem processes, but may also provide clues to improving processing strategies for cochlear implants.Read moreRead less
Transient Receptor Potential Channels (TRPs) As Transducers And Targets In Primary Visceral Afferents
Funder
National Health and Medical Research Council
Funding Amount
$669,130.00
Summary
Transient receptor potential, or TRP channels, are involved in generating many of the sensations we perceive, such as heat, cold, touch and pain. Some TRP channels are specialized to signal pain from visceral organs, which we must investigate if we are to find treatments for visceral pain, which are currently lacking.
Neural Mechanisms In Tactile, Kinaesthetic And Pain Sensation
Funder
National Health and Medical Research Council
Funding Amount
$644,113.00
Summary
Our knowledge of the world around us depends upon our sensory systems which provide a series of windows on the world, enabling the mind and brain to sample information about selected events through the energy forms that impinge upon us. Much of this sensing process takes place through our special sense systems such as the eye, the ear, and the taste and olfactory systems. However, other crucial sensory systems are more generalized throughout the body and are referred to as the somatic sensory sy ....Our knowledge of the world around us depends upon our sensory systems which provide a series of windows on the world, enabling the mind and brain to sample information about selected events through the energy forms that impinge upon us. Much of this sensing process takes place through our special sense systems such as the eye, the ear, and the taste and olfactory systems. However, other crucial sensory systems are more generalized throughout the body and are referred to as the somatic sensory systems. These include our senses of touch, temperature, pain and body position, the last of which is known as our kinaesthetic sense. Our research into the neural mechanisms in sensation and perception is concerned with the tactile, kinaesthetic and pain senses. Although many thousands of nerve fibres travel in the nerves arising from particular regions of the skin or from individual muscles or joints, the sensory nerve fibres that serve these forms of sensation fall into fewer than ten broad classes, made up of five major tactile classes, two or three major kinaesthetic classes, and two broad groups of fibres that mediate pain sensation. However, there is quite striking evidence that when single fibres of these different classes are activated in conscious human subjects, there are marked differences among the fibre classes in their capacity to generate a perceptual response. Under the new NH and MRC grant we propose to examine the transmission and processing of input signals from these fibre classes at the highest levels of the brain, in particular, within the cerebral cortex, in order to reveal the neural mechanisms responsible for their differential perceptual contributions. The proposed analysis will provide fundamental insights into the neural basis for perceptual recognition and will provide information that may be important for our eventual understanding of the disorders of sensory perception that characterize psychiatric conditions such as schizophreniaRead moreRead less
Interaction Of TRP Channels And Inflammatory Mediators: A Critical Role In Visceral Pain
Funder
National Health and Medical Research Council
Funding Amount
$308,747.00
Summary
Transient receptor potential, or TRP channels, are involved in generating many of the sensations we feel, such as touch and pain. The function of these channels can be altered by substances released by the body during inflammation. Some TRP channels have specialized roles in signalling pain from the colon which can be enhanced during colonic inflammation. Understanding how TRP channels and inflammatory mediators function and interact is essential if we are to find treatments for colonic pain.
Using Contextual Effects To Test Theories Of Coding In Visual Cortex
Funder
National Health and Medical Research Council
Funding Amount
$200,500.00
Summary
The visual cortex is the main structure in the brain that processes the visual scene. Cells in the cortex respond selectively to features of the scene such as the orientation of objects, the direction they move and their brightness relative to the background. Cortical cells are arranged in a topographic map of visual space, so that nearby cells respond to light from nearby parts of the image. Recent advances have shown that cells talk to each other so a stimulus in one part of the visual field c ....The visual cortex is the main structure in the brain that processes the visual scene. Cells in the cortex respond selectively to features of the scene such as the orientation of objects, the direction they move and their brightness relative to the background. Cortical cells are arranged in a topographic map of visual space, so that nearby cells respond to light from nearby parts of the image. Recent advances have shown that cells talk to each other so a stimulus in one part of the visual field can influence the responses of cells looking at other regions. This communication between cells is important in guiding the brain to focus on areas of the visual scene that are most important, a process known as attention. An example would be that a mouse moving through the periphery of someone's vision would attract their attention away from objects elsewhere in the scene. This project is designed to study the way that cells in the visual cortex cooperate to guide attention. Attention is important because it reduces the need to process all the detail in the visual scene with the same level of accuracy, leaving more resources free to process what is important. Attention deficits are a problem for people with dyslexia, so understanding the physiological basis of attention is an important goal. As well as attention, the visual system has a range of other mechanisms to select important information from the visual scene. For example, visual adaptation tends to improve the ability to code changes in the visual scene at the expense of reducing the sensitivity of the system overall. This project will investigate the relationship between attentional and adaptive mechanisms in the visual cortex. We expect to establish the precise physiological mechanisms that drive adaptive and attentional mechanisms in the mammalian brain.Read moreRead less