Effects of Acoustic Environment on Tinnitus Behavior in Sound-Exposed Rats
Laboratory studies often rely on a damaging sound exposure to induce tinnitus in animal models. Because the time course and ultimate success of the induction process is not known in advance, it is not unusual to maintain sound-exposed animals for months while they are periodically assessed for behavioral indications of the disorder. To demonstrate the importance of acoustic environment during this period of behavioral screening, sound-exposed rats were tested for tinnitus while housed under quiet or constant noise conditions. More than half of the quiet-housed rats developed behavioral indications of the disorder. None of the noise-housed rats exhibited tinnitus behavior during 2 months of behavioral screening. It is widely assumed that the “phantom sound” of tinnitus reflects abnormal levels of spontaneous activity in the central auditory pathways that are triggered by cochlear injury. Our results suggest that sustained patterns of noise-driven activity may prevent the injury-induced changes in central auditory processing that lead to this hyperactive state. From the perspective of laboratory studies of tinnitus, housing sound-exposed animals in uncontrolled noise levels may significantly reduce the success of induction procedures. From a broader clinical perspective, an early intervention with sound therapy may reduce the risk of tinnitus in individuals who have experienced an acute cochlear injury.
Keywordshyperactivity sound therapy hyperacusis
Support for this research was provided by the Tinnitus Research Consortium, Action on Hearing Loss, and NIDCD grant P30 DC005211. The authors thank ED Young and AM Lauer for their comments on a preliminary version of the manuscript.
Compliance with Ethical Standards
All procedures were reviewed and approved by the Institutional Animal Care and Use Committee of The Johns Hopkins University School of Medicine.
Conflict of Interest
The authors declare that they have no conflict of interest.
- Caspary DM, Llano DA (2017) Auditory thalamic circuits and GABAA receptor function: putative mechanisms in tinnitus pathology. Hear Res 349:197–207Google Scholar
- Eggermont JJ (2017) Effects of long-term non-traumatic noise exposure on the adult central auditory system. Hearing problems without hearing loss. Hear Res 352:12–22Google Scholar
- Irvine DR, Rajan R (1996) Injury- and use-related plasticity in the primary sensory cortex of adult mammals: possible relationship to perceptual learning. Clin Exp Pharmacol Physiol 23(10-11):939–947. https://doi.org/10.1111/j.1440-1681.1996.tb01146.x CrossRefPubMedGoogle Scholar
- Klump GM, Dooling RJ, Fay RR, Stebbins WC (eds) (1995) Methods in comparative acoustics. Birkhauser Verlag, BaselGoogle Scholar
- Kraus KS, Ding D, Jiang H, Lobarinas E, Sun W, Salvi RJ (2011) Relationship between noise-induced hearing-loss, persistent tinnitus and growth-associated protein-43 expression in the rat cochlear nucleus: does synaptic plasticity in ventral cochlear nucleus suppress tinnitus? Neuroscience 194:309–325. https://doi.org/10.1016/j.neuroscience.2011.07.056 CrossRefPubMedCentralPubMedGoogle Scholar
- Middleton JW, Kiritani T, Pedersen C, Turner JG, Shepherd GM, Tzounopoulos T (2011) Mice with behavioral evidence of tinnitus exhibit dorsal cochlear nucleus hyperactivity because of decreased GABAergic inhibition. Proc Natl Acad Sci U S A 108(18):7601–7606. https://doi.org/10.1073/pnas.1100223108 CrossRefPubMedCentralPubMedGoogle Scholar
- Phillips DP, Carr MM (1998) Disturbances of loudness perception. J Am Acad Audiol 9:371–379Google Scholar
- Szczepaniak WS, Moller AR (1996) Effects of (-)-baclofen, clonazepam, and diazepam on tone exposure-induced hyperexcitability of the inferior colliculus in the rat: possible therapeutic implications for pharmacological management of tinnitus and hyperacusis. Hear Res 97(1-2):46–53PubMedGoogle Scholar
- Tanaka C, Chen GD, Hu BH, Chi LH, Li M, Zheng G, Bielefeld EC, Jamesdaniel S, Coling D, Henderson D (2009) The effects of acoustic environment after traumatic noise exposure on hearing and outer hair cells. Hear Res 250(1-2):10–18. https://doi.org/10.1016/j.heares.2008.12.010 CrossRefPubMedGoogle Scholar
- Tunkel DE et al (2014) Clinical practice guideline: tinnitus executive summary. Otolaryngol Head Neck Surg 151(4):533–541Google Scholar
- Young ED, Shofner WP, White JA, Robert JM, Voigt HF (1988) Response properties of cochlear nucleus neurons in relationship to physiological mechanisms. In: Edelman GM, Gall WE, Cowan WM (eds) Auditory function: neurobiological bases of hearing. John Wiley & Sons, New York, pp 277–312Google Scholar