Cortical, Descending And Reflex Control Of Human Inspiratory Muscles
Funder
National Health and Medical Research Council
Funding Amount
$324,500.00
Summary
Of all the skeletal muscles, the breathing muscles perform the most crucial action, that is, they maintain ventilation. The neural control of respiratory muscles must be finely integrated to maintain ventilation while we are awake, asleep, exercising, eating and talking. The neural circuitry for the respiratory muscles is unique. Control of respiratory muscles differs from that of limb muscles because the respiratory motoneurones are activated rhythmically but are controlled via two descending p ....Of all the skeletal muscles, the breathing muscles perform the most crucial action, that is, they maintain ventilation. The neural control of respiratory muscles must be finely integrated to maintain ventilation while we are awake, asleep, exercising, eating and talking. The neural circuitry for the respiratory muscles is unique. Control of respiratory muscles differs from that of limb muscles because the respiratory motoneurones are activated rhythmically but are controlled via two descending pathways. During automatic breathing, descending neural drive arises from the central respiratory pattern generator in the brainstem. Through this system, disturbances are reflexly compensated for without conscious effort. However, in addition, to automatic control, respiration can also be controlled voluntarily from the motor cortex, for example during speech or a breath hold. However, in humans the neural connections and interactions between these two centres are poorly understood. In addition to descending signals, the activity of inspiratory muscles is affected by sensory reflex inputs. The proposed studies will investigate three aspects of the control of human inspiratory muscles that act to 'pump' air into the lungs and upper airway 'dilator' muscles that act to keep the airway open. Because expiration is usually passive during quiet breathing we will focus on the neural control of inspiration. First, we will investigate some of the reflex connections of human 'pump' and 'dilator' muscles in people with and without obstructive sleep apnoea. Second, we will study the descending control of inspiratory muscles using single motor unit recordings. In addition, we will make the first detailed analysis of single motor unit activity from the tongue. This muscle critically helps preserve breathing when we sleep. Finally, we will examine the interactions between the motor cortex and medulla in the control of breathing about which relatively little is known in awake humans.Read moreRead less
My work investigates the neural output to human inspiratory muscles and how it is related to mechanical effectiveness for breathing. The aim is to discover how this relationship can change with respiratory disorders such as chronic obstructive pulmonary disease and obstructive sleep apnoea. I also examine the changes in breathing muscle control in people with spinal cord injury. This work promises new understanding of the basic control of respiration and how it changes with disease.
Central, Reflex And Mechanical Factors In The Control Of Human Breathing Muscles.
Funder
National Health and Medical Research Council
Funding Amount
$497,968.00
Summary
We will study the neural output to human inspiratory muscles and how it is related to mechanical effectiveness for breathing and then how this relationship can change with respiratory disorders such as chronic obstructive pulmonary disease and obstructive sleep apnoea. We will also examine the spinal reflex connections of human breathing muscles in people with spinal cord injury. This work promises new understanding of the basic control of respiration and how it changes with disease.
Competing demands on the axial muscles: Effects, consequences, compensations and mechanisms. Back and neck pain are major health issues and are associated with considerable cost to society and an individual's quality of life. A major issue is to identify factors that increase the chance of developing pain. This project will investigate a novel and innovative possibility; that competition between the many functions of the trunk muscles may increase the possibility for injury. We will study how th ....Competing demands on the axial muscles: Effects, consequences, compensations and mechanisms. Back and neck pain are major health issues and are associated with considerable cost to society and an individual's quality of life. A major issue is to identify factors that increase the chance of developing pain. This project will investigate a novel and innovative possibility; that competition between the many functions of the trunk muscles may increase the possibility for injury. We will study how the nervous system coordinates functions as diverse and movement of the spine, breathing, and control of head and eye movement. A key issue will be to identify whether situations arise in which control of the spine is compromised, potentially leading to increased risk of pain and injury. Such data can aid prevention and rehabilitation.Read moreRead less
The influence of resistance training upon movement control in the elderly. The primary aim of this applied research project is to investigate the impact of resistance training in the elderly. We will assess the responses to training that occur in the elderly, and determine the time course and persistence of adaptation. It is anticipated that the knowledge derived will be applied by clinicians and health practitioners in the design of resistance training programmes for the elderly, and thereby en ....The influence of resistance training upon movement control in the elderly. The primary aim of this applied research project is to investigate the impact of resistance training in the elderly. We will assess the responses to training that occur in the elderly, and determine the time course and persistence of adaptation. It is anticipated that the knowledge derived will be applied by clinicians and health practitioners in the design of resistance training programmes for the elderly, and thereby enhance the performance of tasks encountered in daily living.Read moreRead less
How Changes In The Motor Cortex And Spinal Cord With Exercise Contribute To Fatigue In Humans
Funder
National Health and Medical Research Council
Funding Amount
$311,250.00
Summary
Fatigue with exercise is a common experience in healthy people and can be a problem in many illnesses. With fatigue people are less able to produce force with their muscles. Much of this weakness occurs because of events in the muscles but some results from changes in the nervous system. The size of the contribution of the nervous system to fatigue is not known for the kinds of exercise that cause fatigue in everyday life e.g. prolonged weak contractions like holding the shopping or a plate of f ....Fatigue with exercise is a common experience in healthy people and can be a problem in many illnesses. With fatigue people are less able to produce force with their muscles. Much of this weakness occurs because of events in the muscles but some results from changes in the nervous system. The size of the contribution of the nervous system to fatigue is not known for the kinds of exercise that cause fatigue in everyday life e.g. prolonged weak contractions like holding the shopping or a plate of food, rhythmic contractions like walking or painting a wall, and more vigorous exercise that causes changes in breathing and body temperature. The behaviour of nerve cells in the brain and spinal cord is altered in fatigue but how and why many of these changes occur, and how they affect the control of movements, is poorly understood. Three approaches are planned. In the first set of studies, we will use brain and nerve stimulation to measure the impact of sustained low-level activities on people's ability to drive their muscles fully. We will identify whether such activities, as well as increased demands on other body systems, can cause fatigue in the nervous system. In the second set of studies, we will investigate whether changes in the motor areas of the brain can alter peoples' performance of fatiguing motor tasks or their perception of how much effort the tasks take. Finally, we will use stimulation of the spinal cord to work out why motor nerve cells in the spinal cord fire more slowly with fatigue. Fatigue is an important symptom which is not confined to diseases of any one system in the body. For example, it is a major complaint in multiple sclerosis, cardiac failure, chronic obstructive airway disease, depression and cancer, as well as after chemotherapy, surgery, and viral illness. The implications of better understanding of the contribution of the nervous system to fatigue range from targeting treatments in patients to improving the performance of athletes.Read moreRead less
Preparatory processes in rapid interceptive action. This project investigates the nature of the processes involved in preparing to act in response to a moving object: actions that elite sportspeople perform with amazing precision: timing to within a few thousandths of a second is routine when hitting a ball in tennis and cricket. The average person can be capable of something similar and it means being ready to make the right movement at the right time. Understanding the preparatory processes in ....Preparatory processes in rapid interceptive action. This project investigates the nature of the processes involved in preparing to act in response to a moving object: actions that elite sportspeople perform with amazing precision: timing to within a few thousandths of a second is routine when hitting a ball in tennis and cricket. The average person can be capable of something similar and it means being ready to make the right movement at the right time. Understanding the preparatory processes involved will be a significant scientific advance and knowledge of their workings and limits can contribute to the development of strategies for improving safety in dynamic environments such as city roads. This project will put an Australian laboratory at the cutting edge in this area of research.Read moreRead less
I am a neurophysiologist who examines the neural control of movement and the interaction of sensation and movement in human subjects. I study cortical and motoneuronal events during exercise and muscle fatigue, how cortical connections to the motoneurones change with practice of motor tasks, and whether they can be changed artificially. I also study proprioception i.e. the sensations related to relative position and movement of parts of the body and the production of muscle force.
Experimental and computational assessment of the mechanical, musculo-skeletal and neuromuscular contributions to rhythmic multi-joint arm movements. The human body is a complex mechanical system that is controlled by a vast neural network comprising many millions of connections. To date, realistic descriptions of the interactions between these neuro-mechanical features have proved elusive. This project seeks to develop a mathematical model that accurately describes the essential features of the ....Experimental and computational assessment of the mechanical, musculo-skeletal and neuromuscular contributions to rhythmic multi-joint arm movements. The human body is a complex mechanical system that is controlled by a vast neural network comprising many millions of connections. To date, realistic descriptions of the interactions between these neuro-mechanical features have proved elusive. This project seeks to develop a mathematical model that accurately describes the essential features of the control system for human movement, and yet is simple enough to inform the design of artificial devices to generate or assist movement. The knowledge derived should improve mechanical and neural prosthetic systems, and guide rehabilitation protocols. The work will ultimately provide a considerable benefit to the community by reducing the social cost of a range of movement disorders.Read moreRead less
An inverse control approach to resolving the neural basis of spatial and muscular dependencies in coordinated multi-limb movements. Each year 48,000 Australians suffer from stroke with many survivors left with problems that limit limb function. With reduced duration of hospital care, the opportunities for retraining in the period immediate following stroke are rapidly diminishing. Effective and efficient strategies of rehabilitation that will maximise the level of recovery following stroke will ....An inverse control approach to resolving the neural basis of spatial and muscular dependencies in coordinated multi-limb movements. Each year 48,000 Australians suffer from stroke with many survivors left with problems that limit limb function. With reduced duration of hospital care, the opportunities for retraining in the period immediate following stroke are rapidly diminishing. Effective and efficient strategies of rehabilitation that will maximise the level of recovery following stroke will result in benefits expressed in terms of enhanced quality of life and functional life-span, as well as significantly reduced costs of health care. In understanding the fundamental principles underlying the stability and adaptability of movement coordination, this research is likely to make a significant contribution to the design of programs for movement rehabilitation.Read moreRead less