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Targeting and Reducing Noise Trauma-Induced Tinnitus and Hearing Loss

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Annual rept. 1 Aug 2009-31 Jul 2010

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In this first year, we measured the effect of administering Dexamathesone intravenously immediately following noise trauma and using a 10-day taper in rats. For each animal, we measured their auditory brainstem response and modified startle reflex to measure their ability to hear a silent gap in a continuous tone. With a chronically implanted array of electrodes, we measured neural activity across the auditory midbrain, thought to be involved in the generation tinnitus in humans. After inducing trauma in one ear with a loud, narrow band noise, we measured over the next few days and 4 weeks post-trauma, behavioral evidence of tinnitus, while measuring changes in the response of single neurons that would normally respond to sounds near the tinnitus frequency. For 2 subgroups of the rats, we administered Dexamethasone, the drug of choice for reducing the incidence of tinnitus in humans. For the group that was administered 5mgkg immediately post-trauma, we found no difference in the incidence of tinnitus compared to the control group no drug. For the group that received a taper of 5, 5, 4, 4, 3, 3, 2, 2, 1, 1mgkg on consecutive days, with first dose immediately post-trauma, the neural activity was not much changed from the control group but the behavioral evidence for tinnitus was paradoxically a lot worse than that of the control group.

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  • Anatomy and Physiology
  • Medicine and Medical Research

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