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81st Annual Meeting of the German Society of Oto-Rhino-Laryngology, Head and Neck Surgery

German Society of Oto-Rhino-Laryngology, Head and Neck Surgery

12.05. - 16.05.2010, Wiesbaden

Experimental audiology: an animal model for the investigation of hearing impairment and tinnitus

Meeting Abstract

German Society of Oto-Rhino-Laryngology, Head and Neck Surgery. 81st Annual Meeting of the German Society of Oto-Rhino-Laryngology, Head and Neck Surgery. Wiesbaden, 12.-16.05.2010. Düsseldorf: German Medical Science GMS Publishing House; 2010. Doc10hno071

DOI: 10.3205/10hno071, URN: urn:nbn:de:0183-10hno0716

Published: July 6, 2010

© 2010 Schulze et al.
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Outline

Text

Introduction: Hearing impairment is often caused by damage to the cochlea and loss of cochlear hair cells. In succession, due to the modified activation of the auditory nerve, a counterbalance of lateral inhibitory interactions exists on each level of the auditory pathway that may lead to neuroplastic changes of the functional organization of the central auditory system and eventually a central tinnitus. These central neuro-plastic changes may severely alter sound perception, but are hardly treatable by therapies focusing on the periphery, e.g. the cochlea. To develop new therapies that aim at the described alterations of the functional organization of the central auditory system, invasive investigation of the impaired auditory system is needed to elucidate the central neuronal mechanisms that underlie the hearing impairment. As such studies cannot be carried out in humans due to ethical concerns we here present an animal model to investigate these phenomena.

Methods: Mongolian gerbils were exposed to a loud pure tone (2000 Hz, 115 dB SPL, 75 min) to induce an acoustic trauma and in succession a hearing loss. Hearing impairment was quantified by measurement of the audiograms using brainstem audiometry (ABR) and behavioural methods (reflex conditioning). A modified version of this behavioural test (gap-noise paradigm) was adapted to our animal model to verify if a central tinnitus was established.

Results: We were able to induce a spectrally defined hearing loss in the range of the used pure tone frequency of up to 30 dB that in some animals resulted in a tinnitus percept as demonstrated by behavioural testing. Behaviourally obtained audiograms showed a higher reproducibility and about 10 dB lower thresholds than the ABR obtained audiograms.

Conclusion: An animal model to investigate the central nervous mechanisms of hearing impairment and tinnitus is now available in our lab.