Grant: Project Grant

In Canada, hearing loss is the most common sensory disability in adults and deafness is the most common congenital sensory abnormality in children. A 2006 Australian study estimated that costs to that nation's economy from hearing loss amounted to $10.6 billion per year. On a per capita basis, this translates to a Canadian equivalent of almost $18-billion annually. Although we hear with our brains little is known about what occurs to the brain as a consequence of deafness. In this proposal we will be studying what happens inside the brain following the onset of deafness shortly after birth or in adulthood. Specifically, we will be studying the regions of the brain that normally process sounds in hearing individuals. To do this we will examine deafness in an animal model. This approach will permit us to examine the activity of individual neurons, to examine changes in brain circuitry and activity, and to examine how changes in the brain affect perception and behavior. If the part of the brain that normally processes hearing is not receiving sound, then what is it doing? Is it processing visual information? Is it processing information concerning touch? If it is processing sight, then it may very well help explain the increased visual abilities of deaf humans. Changes in the brain such as this are known as "plastic" changes, or simply "plasticity". These changes are also called "compensatory" because they help the subject enhance their ability to use their remaining senses. Therefore, the goal of this study is to examine the natural plasticity of the brain. Knowing how the brain responds to changes in its inputs in this way will help us develop appropriate therapeutic strategies to help increase brain plasticity and help patients to overcome conditions such as deafness and blindness.