Integrative Role Of Feedback Projections To Cat Primary Visual Cortex
Funder
National Health and Medical Research Council
Funding Amount
$293,321.00
Summary
Although in the last decade termed The Decade of the Brain we have learned a lot about the brain, the gaps in our understanding of brain functions are still enormous. The analysis of information in the sensory parts of the brain appears to be arranged in a distributed - hierarchical way. For example, different types of nerve fibres leaving the eye carry fairly generalised information about the external visual world along distinct parallel information channels. By the time the signals reach cereb ....Although in the last decade termed The Decade of the Brain we have learned a lot about the brain, the gaps in our understanding of brain functions are still enormous. The analysis of information in the sensory parts of the brain appears to be arranged in a distributed - hierarchical way. For example, different types of nerve fibres leaving the eye carry fairly generalised information about the external visual world along distinct parallel information channels. By the time the signals reach cerebral cortex there is a dramatic increase in complexity of visual stimuli to which cells respond (orientation, length and direction of movement of contours became important). There are at least two parallel feedforward information processing streams across the cerebral cortex involving a number of relay stations at each of which there are further specializations. For example, cells in one area appear to respond only to faces while in some other areas cells respond to motion in particular directions almost irrespective of the position of the stimuli. In the human there are more than 30 visual cortical areas. What is very surprising that from all these areas there are extensive feedback pathways running back to the lower-order areas. The feedback pathways appear to largely criss-cross different information processing streams and their function is very poorly understood. We will record from cells in lower-order areas noting the way they respond to different stimuli. Then we will block the feedback pathway from a particular higher-order area by cooling the area to about 10oC. We have confirmed that this prevents nerve impulses leaving the cooled area. Then we repeat our tests on the cell in the lower-order area. Comparing the responses with and without feedback activity will tell us what the feedback is doing. Understanding the function of feedback pathways hopefully would help us to understand the mechanisms underlying some subtle psychoneurological diseases.Read moreRead less
Plasticity Of Sensorimotor Representations In Adult Primate Cortex
Funder
National Health and Medical Research Council
Funding Amount
$554,656.00
Summary
Cells in some regions of the brain, collectively known as the sensorimotor cortex, control our capacity to purposefully move the arms and hands. Damage to these regions in adults causes severe deficits. However, rehabilitative training can restore some control over the muscles. To understand how the brain circuits change to compensate for injury, and what effect rehabilitation may have on these changes, I will study cellular alterations in the movement control pathways in the cerebral cortex.
Representation Of Spatial Coordinate Systems Within Posterior Parietal Cortex And Hippocampus
Funder
National Health and Medical Research Council
Funding Amount
$43,759.00
Summary
To accurately reach for an object or walk from one room to another, our brains need to be able to locate objects around us and detect obstacles in our path. Our amazing ability to make an accurate eye movement directly towards an object such as a cup of tea and move our hand smoothly and directly to the cup is something we all take for granted. However, this ability requires enormous computational complexity which our brains have evolved to handle with ease. We plan to determine the parts of the ....To accurately reach for an object or walk from one room to another, our brains need to be able to locate objects around us and detect obstacles in our path. Our amazing ability to make an accurate eye movement directly towards an object such as a cup of tea and move our hand smoothly and directly to the cup is something we all take for granted. However, this ability requires enormous computational complexity which our brains have evolved to handle with ease. We plan to determine the parts of the brain that perform these computations by using a relatively new technique called functional magnetic resonance imaging or fMRI. This is a non-invasive technique that requires a person to lie in an MRI scanner and perform simple eye movement tasks while the scanner takes images of the brain. With this technology we are able to determine which regions of the brain are most active during the performance of each task, thereby giving us an insight into how the brain works. An area of the brain called the parietal lobe is thought to be involved in the localization of objects, such as reaching for a cup of tea. We will study this area using fMRI to determine how a map of space is represented within the parietal lobe. This region of the brain communicates with another region, the hippocampus which is thought to be involved in navigation, such as walking about the house or driving in the city. Functional MRI will be used to study the hippocampus of our subjects while they perform simple navigational tasks through a maze which is simulated on a computer screen. This will reveal the role hippocampus plays in navigation and the relationship between the parietal lobe and hippocampus. We hope that the greater understanding of hippocampus that will arise from this study will enable us to devise a robust method for imaging hippocampal function with fMRI. We expect that these techniques will aid in the diagnosis of hippocampal abnormalities in patients with temporal lobe epilepsy.Read moreRead less
Molecular And Cellular Changes Following A Cortical Injury: What Role Do They Play In Regeneration?
Funder
National Health and Medical Research Council
Funding Amount
$499,625.00
Summary
Damage to the visual areas of the brain is common after, for example stroke, neurotrauma or hypoxia. The injury often manifests in the form of a scar caused by a specific type of brain cell (astrocyte). This scar acts as a barrier to the cells which transmit information (neurones), preventing re-establishment of connectivity, thus functional recovery. We will see if we can reduce this scar and enhance re-connectivity after injury by blocking some of the molecules that brain cells express.
Word finding difficulties are the most common type of language impairment following stroke, causing considerable frustration and distress for the individual and their family and friends. Current available language therapies are not always effective. This project aims to (1) develop and test new language treatments for stroke sufferers, and (2) find out how language therapy works in the brain. Outcomes will include improved treatment of communication disorders after stroke.
Epilepsy: Is It An Inherent State Of Cortical Hyper-excitability?
Funder
National Health and Medical Research Council
Funding Amount
$370,640.00
Summary
Transcranial magnetic stimulation (TMS) is a safe way to study the human brain and changes associated with epilepsy. I will use TMS to examine the effect of refractory epilepsy and recurrent seizures on the brain over time and how this differs to well controlled epilepsy and provoked isolated seizures. I will also explore the potential of using TMS to predict responsiveness to medication soon after starting treatment.
Bilateral Movement Therapy In Post-stroke Hemiparesis
Funder
National Health and Medical Research Council
Funding Amount
$265,993.00
Summary
Stroke is the leading cause of long-term disability in adults in Australia, accounting for approximately 25% of all disability. A common motor disability resulting from stroke is hemiparesis, weakness or paralysis on one side of the body. This disability severely impairs an individual's capacity to perform activities of daily living, making them dependent on relatives and health professionals for daily care. By developing effective interventions to treat stroke-induced hemiparesis both the disab ....Stroke is the leading cause of long-term disability in adults in Australia, accounting for approximately 25% of all disability. A common motor disability resulting from stroke is hemiparesis, weakness or paralysis on one side of the body. This disability severely impairs an individual's capacity to perform activities of daily living, making them dependent on relatives and health professionals for daily care. By developing effective interventions to treat stroke-induced hemiparesis both the disability caused by stroke and the associated personal and financial costs will be lessened. A number of interventions focusing on the affected side (unilateral), including active movements and muscle stimulation are being investigated as possible treatments for stroke-induced hemiparesis. Recent evidence suggests that involving the unaffected side simultaneously (bilateral therapies) could be effective, and may provide addtional benefits over unilateral therapies. The aim of this research is to thoroughly examine the effectiveness of bilateral therapies by incorporating them into established interventions. The findings from these studies will aid in the development and refinement of movement therapies aimed at promoting recovery from stroke-induced hemiparesis.Read moreRead less
Over thirty different areas, comprising nearly half the primate cerebral cortex, are involved in processing visual information. From the anatomical viewpoint, each of these areas should be capable of receiving visual information independently, through parallel anatomical channels involving the brainstem. Yet, it has been observed that lesion of one particular area (the primary visual area, V1) results in loss of vision. This raises several questions. What type of visual information is carried by ....Over thirty different areas, comprising nearly half the primate cerebral cortex, are involved in processing visual information. From the anatomical viewpoint, each of these areas should be capable of receiving visual information independently, through parallel anatomical channels involving the brainstem. Yet, it has been observed that lesion of one particular area (the primary visual area, V1) results in loss of vision. This raises several questions. What type of visual information is carried by the parallel pathways to the other visual areas? Why aren t these other areas capable of sustaining vision without V1? Do V1 lesions trigger changes in the adult brain, which affect the other visual areas? As a step towards answering these questions, we will study the neural pathways that convey visual information directly to the middle temporal area (MT). MT is one of the best-characterised visual areas, and the anatomy of its neural inputs is well known, facilitating the interpretation of the results. We will investigate the type of visual information being sent to MT after lesions of V1, as well as the changes in the electrical responses of MT cells which result from this type of condition. This is a basic science study, the primary benefit of which will be advancement of knowledge on the mechanisms that underlie visual processing in normal and pathological situations. However, this type of work may also lay the groundwork for developments in areas of applied research. These may include medicine (e.g. the design of better rehabilitation strategies for people with brain damage), robotics- artificial intelligence (e.g. the development of more robust artificial systems capable of vision), and cognitive sciences (e.g. a better understanding of factors that limit human responses to visual stimuli).Read moreRead less