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
Peripheral Neuropathy And Pain: Role Of The Sphingosine Kinase-sphingosine 1-phosphate System
Funder
National Health and Medical Research Council
Funding Amount
$282,905.00
Summary
Understanding the neural mechanisms that generate pathological pain remains one of the essential goals for the development of effective treatments for pain, chronic pain with less side effects. Lipids are able to modulate pain perception. We will determine the role of a molecule named sphingosine 1-phosphate as a basis for the development of therapies for the treatment of neuropathic pain.
The Neural Control Of Serotonin Release From Intestinal Enterochromaffin (EC) Cells
Funder
National Health and Medical Research Council
Funding Amount
$117,187.00
Summary
Many functional gastrointestinal problems are believed to be caused by a disruption of the normal functioning of the nerves within the wall of the gut. These nerves are believed to receive information about the contents of the intestine from a specialised class of cell lining the inside wall of the gut called the enterochromaffin cell. The enterochromaffin cell does this job by modulating the release of the transmitter serotonin. In some disorders, like the Irritable Bowel Syndrome (IBS) which c ....Many functional gastrointestinal problems are believed to be caused by a disruption of the normal functioning of the nerves within the wall of the gut. These nerves are believed to receive information about the contents of the intestine from a specialised class of cell lining the inside wall of the gut called the enterochromaffin cell. The enterochromaffin cell does this job by modulating the release of the transmitter serotonin. In some disorders, like the Irritable Bowel Syndrome (IBS) which can affect the upper and lower intestine, the information that serotonin carries can become confused. Thus, the control of the release of serotonin from the enteroendocrine cell is an important process to understand in health and in disease. We will investigate this release directly in isolated tissues from guinea pig small and large intestine and from human large intestine. This study will examine the role of serotonin and the modulation of its release from the enterochromaffin cell. Problems with serotonin release may underlie disease, thus, understanding how this release is controlled will provide a foundation for new and specific therapies that target channels or receptors specific to the release of serotonin. These data could help to develop therapies for gastrointestinal problems such as the IBS, chronic intestinal pseudo-obstruction and gastro-oesophageal reflux disease. The release of serotonin is also intimately linked with the diarrhea associated with cholera and anti-cancer treatments. The proposed study will contribute to the ongoing development of specific therapies that block serotonin receptors on the nerve terminal and will lead to new therapies that compliment existing therapies by modulating the release of serotonin.Read moreRead less