Human Muscle Stretch Reflexes: The Effects Of Stimulus Properties, Muscle State And Subject Intention
Funder
National Health and Medical Research Council
Funding Amount
$170,604.00
Summary
The best known muscle reflex is the tendon jerk, which is usually evoked by tapping the muscle tendon with a small hammer. This tap imposes a very rapid stretch on the muscle, which produces a stretch reflex. Different stretch responses, however, can be observed to slow or fast stretches, or to vibration of muscle. Normally, when the muscles of a relaxed person are stretched, no active response is observed. However, when the person is engaged in a task and contracting their muscles, then stretch ....The best known muscle reflex is the tendon jerk, which is usually evoked by tapping the muscle tendon with a small hammer. This tap imposes a very rapid stretch on the muscle, which produces a stretch reflex. Different stretch responses, however, can be observed to slow or fast stretches, or to vibration of muscle. Normally, when the muscles of a relaxed person are stretched, no active response is observed. However, when the person is engaged in a task and contracting their muscles, then stretch modulates the muscle activity such that an increase in contraction of the muscle opposes the stretch and defends the position of the joint against the external disturbance. This is the everyday situation in which stretch reflexes operate. Despite extensive investigation for over a hundred years, there is still no consensus among researchers about the behaviour of stretch reflexes nor about their role in the control of movement. Even the demarcation of reflex from voluntary muscle activity is not always certain. One of the outstanding features of stretch reflexes is the variability of their behaviour, which depends on the particular muscle involved, its level of contraction, the type of stretch and the task in which the person is engaged. This variability has made it difficult for researchers to determine the role of reflexes in the control of movement. In order to study stretch reflex behaviour in human subjects, we will measure the electrical activity of elbow muscles, the elbow position and the force generated at the joint under a variety of conditions. A series of five experiments will investigate specific unresolved issues such as the effect of subject intention on the modulation of muscle activity and how altered modulation of muscle activity may change the stiffness of our limbs. The objective of the experimental series is to fill in important gaps in the picture of the behaviour of the stretch reflex.Read moreRead less
Practical multi-receiver passive radar with low-cost synchronisation. This project aims to address the current challenges of developing practical multi-receiver passive radar systems, through the development of advanced receiver synchronisation techniques, which do not require the deployment of costly infrastructure. The project will develop novel algorithms and techniques that enable synchronous combining of data from multiple radars, allowing for the detection of smaller targets and significan ....Practical multi-receiver passive radar with low-cost synchronisation. This project aims to address the current challenges of developing practical multi-receiver passive radar systems, through the development of advanced receiver synchronisation techniques, which do not require the deployment of costly infrastructure. The project will develop novel algorithms and techniques that enable synchronous combining of data from multiple radars, allowing for the detection of smaller targets and significantly extending the radar coverage zone. The expected outcomes of this project include improved performance of passive radar systems and the advancement of radar technology. The benefits of this project include new applications in areas such as traffic monitoring, drone detection and national security.Read moreRead less
Mechanisms And Treatment Of Upper Airway Collapse In Obstructive Sleep Apnoea
Funder
National Health and Medical Research Council
Funding Amount
$328,668.00
Summary
Obstructive sleep apnoea (OSA) is characterized by intermittent closure of the upper airway (throat) resulting in episodes of decreased blood oxygen levels, increased blood pressure and disturbed sleep. Repetitive overnight arousals from sleep cause excessive daytime tiredness and lethargy, which have major consequences for social well-being and productivity in our community. OSA is a common condition, affecting as many as 2 to 4% of middle aged adults, and is associated with an increased cardio ....Obstructive sleep apnoea (OSA) is characterized by intermittent closure of the upper airway (throat) resulting in episodes of decreased blood oxygen levels, increased blood pressure and disturbed sleep. Repetitive overnight arousals from sleep cause excessive daytime tiredness and lethargy, which have major consequences for social well-being and productivity in our community. OSA is a common condition, affecting as many as 2 to 4% of middle aged adults, and is associated with an increased cardiovascular risk, however the mechanisms underlying the increased upper airway collapsibility in individuals with OSA are not well understood. The proposed studies represent a series of investigations into fundamental mechanisms of neural and mechanical control of upper airway patency, how these mechanisms act to stabilize the upper airway, and whether these reflex control mechanisms can be manipulated to provide a novel treatment for OSA.Read moreRead less
Neurochemicals In The Control Of Human Bladder Function
Funder
National Health and Medical Research Council
Funding Amount
$196,018.00
Summary
The problem of urinary incontinence has received little attention from the medical and scientific research community until the last 10-15 years. Urinary incontinence can cause severe distress and is a taboo subject, even though it affects 30-40% of women. Public figures speak out about their experiences with breast cancer or heart disease, but not about leakage of urine. Elderly people with incontinence are forced into nursing homes, with major costs to the community. Incontinence is a major cli ....The problem of urinary incontinence has received little attention from the medical and scientific research community until the last 10-15 years. Urinary incontinence can cause severe distress and is a taboo subject, even though it affects 30-40% of women. Public figures speak out about their experiences with breast cancer or heart disease, but not about leakage of urine. Elderly people with incontinence are forced into nursing homes, with major costs to the community. Incontinence is a major clinical problem: although over 800 new patients per annum are seen at our Pelvic Floor Unit, the waiting time for a first appointment is 14-15 weeks. There are four main types of urine leakage: - stress incontinence (weak pelvic floor muscles); - overflow incontinence (seen in men with prostatic hypertrophy); - sensory urgency (frequent, uncomfortable desire to urinate); and - detrusor instability (bladder muscle spasms with leakage). We are primarily interested in detrusor instability and sensory urgency, which cause 35% of incontinence in general, but up to 85% of cases in the elderly. Patients suffer from an urgent desire to visit the toilet frequently, and may leak urine if they cannot reach the toilet quickly. Unlike stress incontinence, it cannot be corrected by pelvic floor surgery. Drug treatment is often unsuccessful, with many unacceptable side effects. In our research group, we have found that the sensory nerve which convey the sensation of bladder fullness, are overabundant and display increased amounts of neurochemicals. Our studies in isolated bladder muscle from these patients have shown abnormalities in responsiveness. Thus bladder from women with urge incontinence is resistant to drugs which abolish contraction in normal bladder. In this project we plan to find out why such changes occur. We will use new techniques to study bladder nerves and the receptors which convey the message to contract the bladder muscle.Read moreRead less
Group orbits in garmonic analysis and ergodic theory. Researchers from many areas need a type of mathematical analysis which involves the behaviour of a system - which may be a set of data points - under repeated application of some operation or group of operations. The structures arising from this kind of process are known as group orbits. The project gives information about their nature. Two major types of orbits are considered, coming from actions of discrete groups on measure spaces, and fro ....Group orbits in garmonic analysis and ergodic theory. Researchers from many areas need a type of mathematical analysis which involves the behaviour of a system - which may be a set of data points - under repeated application of some operation or group of operations. The structures arising from this kind of process are known as group orbits. The project gives information about their nature. Two major types of orbits are considered, coming from actions of discrete groups on measure spaces, and from smooth actions of Lie groups on manifolds, where powerful geometric methods are available. The project will yield new understandings of entropy, and new approaches to Fourier analysis.Read moreRead less
Ergodic theory and number theory. Recent advances in the theory of measured dynamical systems investigated by the proponents include new versions of entropy, and the study of spectral theory for non-singular systems. These will be further developed in this joint project with the French CNRS. The results are expected to have interesting applications in physics and number theory.
Operator Integrals and Derivatives. The project is a contribution to the study of non-commutative differential and integral calculus. The novelty of the present project lies in the study of smoothness properties of functions whose domains and ranges are spaces of unbounded, non-commuting operators on some Hilbert space. Our general approach will be based on a detailed investigation of properties of double operator integrals, which permit smoothness estimates of operator-functions. It can be expe ....Operator Integrals and Derivatives. The project is a contribution to the study of non-commutative differential and integral calculus. The novelty of the present project lies in the study of smoothness properties of functions whose domains and ranges are spaces of unbounded, non-commuting operators on some Hilbert space. Our general approach will be based on a detailed investigation of properties of double operator integrals, which permit smoothness estimates of operator-functions. It can be expected that the new techniques generated will find further application in areas of mathematical physics and non-commutative geometry related to quantized calculus.
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