Cell Type Specification In Developing CNS: Functional Analysis Of Sox14
Funder
National Health and Medical Research Council
Funding Amount
$468,055.00
Summary
The central nervous system (CNS) is the most complex organ in the body. The vast majority of nerve cells in the CNS are classified as 'interneurons'. These cells relay sensory information and motor commands within the CNS. Abnormal functioning of interneurons is likely to be the underlying cause of some, if not many, human nervous system diseases. However, very little is known of the precise anatomy and function of interneurons, which genes control their development, and how these functions are ....The central nervous system (CNS) is the most complex organ in the body. The vast majority of nerve cells in the CNS are classified as 'interneurons'. These cells relay sensory information and motor commands within the CNS. Abnormal functioning of interneurons is likely to be the underlying cause of some, if not many, human nervous system diseases. However, very little is known of the precise anatomy and function of interneurons, which genes control their development, and how these functions are maintained in the adult. This has been largely due to a lack of efficient and reliable methods to identify and study interneurons. We have previously discovered that a gene termed Sox14 is active in distinct interneuron groups in the embryonic brain and spinal cord. Sox14 is a member of the Sox gene family, many of which act as genetic switches to control cell and tissue development. We found that Sox14 has been extremely well conserved throughout evolution and is active in similar interneuron groups in a number of animal species. These studies led us to hypothesise that Sox14 controls a critical molecular step in the generation of certain interneurons that may be involved in reflexes, locomotion or motor coordination. In this project, we will investigate both the role of Sox14 in interneuron development and the functions of interneurons in which this gene is active. We will do so by combining modern molecular and genetic techniques with physiological approaches. This project will reveal critical molecular steps in CNS development and determine the functions of a specific group of interneurons. To this end, we will generate mouse strains in which a specific group of interneurons are genetically marked and can be manipulated during development. We envisage that these mice with 'modified brain circuits' will become unique resources for future investigations of selected interneuron types and their functions.Read moreRead less
We are able to identify and discriminate objects in the world because of exquisitely detailed and rapid processing of sensory information by neurons in the cortex of the brain. In this project we will examine these operations in neurons in the cortex that receive input from the large face whiskers of the rat. These whiskers are used for fine-grain discrimination and for gauging distance. They are deflected by being actively moved, under muscle control, over objects (active touch) or by being pas ....We are able to identify and discriminate objects in the world because of exquisitely detailed and rapid processing of sensory information by neurons in the cortex of the brain. In this project we will examine these operations in neurons in the cortex that receive input from the large face whiskers of the rat. These whiskers are used for fine-grain discrimination and for gauging distance. They are deflected by being actively moved, under muscle control, over objects (active touch) or by being passively deflected by objects. Deflection results in inputs to the brain that are processed to form the neural basis for very finely detailed perceptual behaviour. In rats, with impoverished visual and auditory senses, the whiskers are the major sensory system for interacting with the world, and are used in navigating the environment and in finding and distinguishing foods. Thus they contribute strongly to the remarkable success of this species. This elegant sensory system has a number of advantages that make it a very good model for the study of brain mechanisms responsible for active fine-grain sensory function. We plan to take advantage of the unique features of this system to define the information processing that occurs in the cortex in this elegantly complex system. This will address an issue relevant to all sensory systems - namely the neural basis of complex fine grain perceptual behaviour. Understanding the mechanisms underlying active tactile perception also has relevance to clinical conditions involving deficits in active touch e.g., in diabetic polyneuropathy (which eventually affects ~50% of diabetics), in leprosy (in which an early sign is damage to active touch). Knowledge of the core brain processes in active touch gained in this study could eventually underpin the ameliorative technologies for such deficits.Read moreRead less
Generation Of Complex Responses In Retinal Ganglion Cells
Funder
National Health and Medical Research Council
Funding Amount
$490,500.00
Summary
The retinal ganglion cells, whose axons form the optic nerve, comprise numerous distinct types, which respond to visual stimuli in either a simple or complex manner. The project will investigate how the complex responses of the direction-selective ganglion cells (DSGCs) and the local-edge-detector ganglion cells (LEDs) are generated. It appears that the retinal neurons providing inhibitory input to DSGCs and LEDs use different neurotransmitters, and the project will investigate how this shapes t ....The retinal ganglion cells, whose axons form the optic nerve, comprise numerous distinct types, which respond to visual stimuli in either a simple or complex manner. The project will investigate how the complex responses of the direction-selective ganglion cells (DSGCs) and the local-edge-detector ganglion cells (LEDs) are generated. It appears that the retinal neurons providing inhibitory input to DSGCs and LEDs use different neurotransmitters, and the project will investigate how this shapes the response properties of the ganglion cells. This will be done both by recording the visually evoked responses of the ganglion cells in an isolated preparation of the retina and by using two-photon laser-scanning microscopy to functionally image the neuronal interactions between the neurons that inhibit the DSGCs.Read moreRead less
Investigating Action Potential Initiation And Propagation In Neurons Using Voltage-sensitive Dyes
Funder
National Health and Medical Research Council
Funding Amount
$317,076.00
Summary
Nerve impulses, or action potentials, are the fundamental electrical signals used by the nervous system for communication. Critical to an understanding of neuronal function is the knowledge of where these events are initiated and how they propagate. Furthermore, this knowledge is required for understanding what goes wrong under conditions where there is a disturbance in neuronal communication, as occurs in many neurological disorders such as multiple sclerosis and epilepsy.
Properties Of Dendritic Spines And Their Role In Synaptic Plasticity
Funder
National Health and Medical Research Council
Funding Amount
$336,767.00
Summary
Connections between nerve cells in the brain often occur onto enlarged protrusions called dendritic spines. This proposal will investigate the properties of dendritic spines, and relate differences in spine properties to synaptic plasticity. This information can be used to better understand and treat neurological disorders associated with spine malfunction, as occur in some forms of mental retardation, and may help with understanding the memory loss that occurs during ageing and dementia.
Intraocular Transplantation And Regeneration Of Retinofugal Pathways In Rodents
Funder
National Health and Medical Research Council
Funding Amount
$370,937.00
Summary
In the adult human brain and spinal cord there is little or no intrinsic capacity for replacement of lost or dying neurons, and there is minimal spontaneous repair of nerve fibre pathways. Thus traumatic injuries, stroke, or loss of neurons due to chronic degenerative disease result in functional impairments that are usually severe and long-lasting. The personal, social and economic costs associated with these neurological problems are enormous. New ways must be found of protecting and-or replen ....In the adult human brain and spinal cord there is little or no intrinsic capacity for replacement of lost or dying neurons, and there is minimal spontaneous repair of nerve fibre pathways. Thus traumatic injuries, stroke, or loss of neurons due to chronic degenerative disease result in functional impairments that are usually severe and long-lasting. The personal, social and economic costs associated with these neurological problems are enormous. New ways must be found of protecting and-or replenishing nerve cells in damaged CNS gray matter, and new methods are also required to help reconstruct fibre tracts after injury. Using the visual system as an experimental model, the aims of the proposed work are to develop novel transplantation and surgical strategies to: (i) Incorporate new cells into retinae that have been selectively depleted of endogenous neurons (ii) Promote the effective regeneration of large numbers of adult retinal axons through prosthetic peripheral nerve bridging grafts and into host CNS distal to the injury. The results obtained from the first series of studies will not only be of direct relevance to the future treatment of human retinal degenerative disorders, but will also increase our overall understanding of how best to ensure the differentiation and stable integration of different types of transplanted cells within the compromised host CNS. The second series of experiments should lead to an entirely new approach to nerve pathway reconstruction, relevant to both brain and spinal cord injuries. The ultimate aim of this experimental work is to improve the management and treatment of human CNS injury and disease, leading to better functional recovery and rehabilitation.Read moreRead less
Insulin-regulated Aminopeptidase, Glucose And Memory
Funder
National Health and Medical Research Council
Funding Amount
$555,693.00
Summary
We have previously shown that inhibitors of IRAP improve performance in memory tasks in normal and memory impaired animals and are currently developing new treatments for memory loss using IRAP as a target. In this study, we will investigate the physiological roles of IRAP and its association with intracellular proteins. The knowledge obtained will provide insights of how the brain process memory and confirm the suitability of IRAP inhibitors as drugs for treating memory deficits.
DEVELOPMENT OF CARDIOVASCULAR CONTROL DURING SLEEP IN HUMAN INFANTS AFTER PRETERM BIRTH
Funder
National Health and Medical Research Council
Funding Amount
$358,537.00
Summary
Infants spend the major part of their life in sleep, and the period between birth and 6 months of age sees dramatic changes in their sleep organisation. Coincidently, there are dramatic developmental changes in the infant's heart and blood pressure control systems, and the ability to compensate for stress such as falls of blood pressure (hypotension) or in the level of oxygen in the blood (hypoxaemia). In infants born preterm, the risks of hypoxaemia, and even death are significantly greater dur ....Infants spend the major part of their life in sleep, and the period between birth and 6 months of age sees dramatic changes in their sleep organisation. Coincidently, there are dramatic developmental changes in the infant's heart and blood pressure control systems, and the ability to compensate for stress such as falls of blood pressure (hypotension) or in the level of oxygen in the blood (hypoxaemia). In infants born preterm, the risks of hypoxaemia, and even death are significantly greater during sleep than during wakefulness, but why this is so is uncertain. This study will examine the ability of infants to respond to stress during sleep. Four groups of infants will be examined: healthy infants born at normal gestation; healthy infants born prematurely (preterm); preterm infants who have experienced mild hypoxaemia soon after birth; and preterm infants who have suffered more severe hypoxaemia because of lung disease. Infants will be studied in a sleep laboratory during day-time sleep, and their ability to control blood pressure will be determined. By contrasting the effectiveness of blood pressure control between the infant groups we aim to determine whether preterm infants have lasting problems as a result of their premature birth, or their exposure to hypoxaemia. By contrasting infants in sleep and wakefulness, we aim to assess whether the risks of poorer blood pressure control are greater in sleep.Read moreRead less
A Novel Mechanism For The Maintenance Of Catecholamine Synthesis
Funder
National Health and Medical Research Council
Funding Amount
$356,250.00
Summary
Stress causes an acute response that prepares us for flight or a fight and an adaptive response that requires days to establish. The catecholamines, including adrenaline, noradrenaline and dopamine are critical to both the acute and adaptive stress responses. They are secreted from cells at the level of the nervous system and the adrenal gland. We all respond differently to stress and if we do not cope we can become hypertensive or depressed. These pathologies require drug management and the dru ....Stress causes an acute response that prepares us for flight or a fight and an adaptive response that requires days to establish. The catecholamines, including adrenaline, noradrenaline and dopamine are critical to both the acute and adaptive stress responses. They are secreted from cells at the level of the nervous system and the adrenal gland. We all respond differently to stress and if we do not cope we can become hypertensive or depressed. These pathologies require drug management and the drugs all affect the catecholamine systems. Tyrosine hydroxylase controls catecholamine synthesis and it is activated in both the acute and adaptive phases of the stress response in order to replace catecholamines that have been secreted. Tyrosine hydroxylase is activated by protein phosphorylation in the acute phase and by the synthesis of new tyrosine hydroxylase in the adaptive phase. We have now discovered an additional and novel phase that we refer to as sustained tyrosine hydroxylase activation. This phase spans at least the period between the acute (mins) and adaptive phases (days). It involves the sustained phosphorylation of tyrosine hydroxylase and its mechanism appears to differ from the other two phases. In this project we will answer three questions. Does sustained tyrosine hydroxylase activation: 1 Occur in response to many stimuli and in many catecholamine cell types? 2 Occur by a single mechanism, different to the other phases, in all circumstances? 3 Play a role in the control of blood pressure and depression? This project will provide fundamental data about the mechanisms and consequences of sustained tyrosine hydroxylase activation, which is a part of the stress response not previously discovered. The data may impact on the way we design drugs to control stress responses, including antidepressants and antihypertensives.Read moreRead less
Astrocyte-Neuron Communication: Unravelling The Role Of Astrocytes In The Modulation Of Neuronal Circuits
Funder
National Health and Medical Research Council
Funding Amount
$403,064.00
Summary
Astrocytes, a type of glial cell, are the most numerous cell type in the brain. They outnumber their neuronal counterparts by ten times and make up almost 90% of adult brain weight. They were originally thought to have only a supportive role in brain metabolism and the regulation of brain blood flow. It is now known that they also modulate neurons and their synapses through release of vesicles containing specific substances and have key roles in some neuropathic (e.g. pain and epilepsy) and neur ....Astrocytes, a type of glial cell, are the most numerous cell type in the brain. They outnumber their neuronal counterparts by ten times and make up almost 90% of adult brain weight. They were originally thought to have only a supportive role in brain metabolism and the regulation of brain blood flow. It is now known that they also modulate neurons and their synapses through release of vesicles containing specific substances and have key roles in some neuropathic (e.g. pain and epilepsy) and neurodegenerative states (e.g. Alzheimer's disease, Parkinson's disease, and multiple sclerosis). Many of these diseases are associated with a pathological astrocyte process known as 'reactivity'. This process remains enigmatic, resulting in so-called reactive gliosis, a reaction characterized by changes in gene expression, cell enlargement and changes in cell shape, and, in some cases, cell division. Most of the research on astrocyte reactivity has focused on the impairment of astrocyte metabolic activities. Comparatively little is known about the effect of reactive gliosis on so called 'newer' astrocyte roles such as their ability to interact with each other and nearby neurons using exocytosis of gliotransmitters (GTs: glutamate and ATP) and neurotrophic factors (NTFs: glial and brain derived neurotrophic factors). This project will both further investigate the normal mechanisms of astrocyte-neuron communication, and examine the effects of astrocyte reactivity on these mechanisms. The aim is to identify possible therapeutic targets to ameliorate the detrimental affects of neurodegeneration.Read moreRead less