Grant: Project Grant

Tinnitus is a bothersome noise or ringing in the ears occurring in the absence of external auditory stimulation. It is a common problem affecting approximately 1 person in 4 in Canada and is most often linked to age-related hearing loss. In around 6% of these cases, tinnitus is so distracting that it interferes with several central aspects of their lives including sleeping and working, and in the worse cases can lead to even depression and suicide. There is currently no effective treatment for tinnitus in large part because the mechanisms causing it are mostly unknown. Aberrant rewiring of the sound processing areas of the brain is thought to play an important role in the emergence of tinnitus, but the very nature of this reorganization remains very controversial. The primary goal of this project is to understand precisely if and how the brain is reorganized in tinnitus sufferers and to relate identified brain changes to individual tinnitus parameters and measures of tinnitus severity. We propose experiments that will make use of novel neurophysiological techniques we have developed to map the auditory cortex's functional organization using in high-resolution magnetoencephalography (MEG). MEG is the ideal neuroimaging technique to achieve this as it operates in silence, as opposed to fMRI, and has a higher spatial resolution than EEG. We will, among other objectives, test the hypothesis that tinnitus in humans is associated with an over-representation of the dominant tinnitus frequency within the auditory cortex, and determine which neurophysiological measures are the best correlates of tinnitus severity. We expect that our findings will significantly enhance our understanding of the mechanisms underlying the emergence of tinnitus and will also hopefully provide new therapeutic targets for future research.