A decade ago the adult brain was thought of as a structurally-fixed organ. Against this are well-documented cases of slow recovery after massive injuries or stroke. Simple models of brain injury using the tactile, visual and auditory systems of animals as models have now revealed multiple stages of recovery (plasticity). Some of these are inbuilt into the wiring of the neural systems such that functional plasticity can result without the need for any structural or cellular changes. A second grou ....A decade ago the adult brain was thought of as a structurally-fixed organ. Against this are well-documented cases of slow recovery after massive injuries or stroke. Simple models of brain injury using the tactile, visual and auditory systems of animals as models have now revealed multiple stages of recovery (plasticity). Some of these are inbuilt into the wiring of the neural systems such that functional plasticity can result without the need for any structural or cellular changes. A second group of plastic phenomena depend upon minute changes in the connections between neurons and these are invoked in the first few days following an injury (synaptic plasticity; changes in the pattern and strength of the connections between neurons). Aside from being model systems, there are also parallels of this plasticity with clinical situations such as losses in hearing and sight, and of the adaptations made by the brain in response to prosthetics (e.g. bionic ear) and resorative surgery but the degree of relevance for these situations is unclear. An intriguing aspect of the experiments on auditory and visual systems is that neurons with inputs from both ears, or both eyes, undergo the plastic changes when the relevant sense organ on only one side is damaged but the other is intact. In fact, on the basis of the limited available evidence, it appears that the changes are independent of there being a normal input from the other side. This is difficult to explain in terms of the modern understanding neuronal plasticity at a cellular level. It is thus proposed to study both auditory and visual models of this brain plasticity with stimuli which are systematically varied to extract the extent of bilateral interaction in the induced plasticity. This will enable prediction of how these plasticity mechanisms will be involved in adaptations made to prosthetics and surgical corrections.Read moreRead less
Organization And Function Of Primate Auditory Cortex
Funder
National Health and Medical Research Council
Funding Amount
$271,671.00
Summary
The conscious perception of speech and other sounds depends on processing within a brain region known as the auditory cortex. Compared to other brain areas, relatively little is known about the organization and function of this structure. Recent studies have proposed that the auditory cortex may be anatomically subdivided into functional modules, each of which is specialized for processing different types of information. However, the evidence for multiple processing streams is fragmentary, and n ....The conscious perception of speech and other sounds depends on processing within a brain region known as the auditory cortex. Compared to other brain areas, relatively little is known about the organization and function of this structure. Recent studies have proposed that the auditory cortex may be anatomically subdivided into functional modules, each of which is specialized for processing different types of information. However, the evidence for multiple processing streams is fragmentary, and not entirely consistent. The proposed experiments will combine anatomical and physiological approaches to evaluate the functional organization of auditory cortex in the primate brain. We will map the electrical responses of single brain cells to various complex sounds across the brain surface, and inject dyes to label pathways linking brain areas to one another. The data will allow us to determine whether specific subdivisions of the auditory cortex are specialized for processing different types of infomation, and whether specific subdivisions are linked together to form processing streams specialized for sound recognition and space perception. The results will advance our understanding of the neuronal processing involved in the perception of sound, with possible implications for speech perception. This will help to understand the consequences of brain damage, and may inform the development of hearing aids and artificial voice recognition systems. In addition, this study will help to develop a primate model for studying brain mechanisms of sound recognition that should be useful in research on cochlear implants.Read moreRead less
Combining input from vision and hearing greatly enhances perception when information from one of these senses is degraded or incomplete, such as when tracking objects in foggy, dark or noisy places. This enhancement is of considerable importance because degraded input is the daily situation faced by many people with hearing or vision impairment. We will study the neural processes underlying our ability to combine vision and hearing to create a more reliable and accurate perception of the world.