The olivocochlear bundle (OCB) consists of lateral efferent fibers that innervate afferent dendrites beneath inner hair cells (IHCs), and medial efferent fibers that innervate outer hair cells (OHCs) directly. A great deal is known about the hair cells and their fate following acoustic over- stimulation and exposure to ototoxic drugs and how their loss influences basic auditory function. By contrast, little is known about the possible contributions made by OCB to either normal cochlear function or to susceptibility to cochlear damage, and what little is known is primarily based on studies of the medial efferent system only. The primary goals of this project are to examine lateral and medial efferent influences on (a) suprathreshold auditory function and individual susceptibility to damage; (b) hair cell loss and threshold shifts caused by noise and three ototoxic drugs that differ in their site of action within the cochlea (kainic acid, a glutamate analogues that temporarily disrupts IHC/afferent fiber synapse; kanamycin, a aminoglycoside that destroys OHCs; and carboplatin, and antineoplastic agent that selectively destroys IHCs in the chinchilla cochlea); and (3) recovery of IHC/afferent fiber synapses after kainate- induced excitotoxic damage. The experiments proposed are logical outgrowths of our previous studies of OCB involvement in """"""""toughening"""""""" and noise-induced hearing loss, and of kainic acid excitotoxicity. Physiological measures will be obtained from awake animals before and after complete transection of the inferior vestibular nerve as it enters the internal auditory meatus. Physiological measures will include tests of cochlear non-linearity, frequency resolution, and temporal resolution, performed in quiet and in the presence of making noise. In a subset of experiments, chronic infusion of strychnine will be used to disable the medial efferent system, to separate our medial from lateral efferent effects. The results will provide important information regarding the role of the OCB in susceptibility to cochlear damage caused by noise and ototoxic drugs, as well as its role in normal auditory function.

Project Start
2002-01-01
Project End
2002-12-31
Budget Start
1997-10-01
Budget End
1998-09-30
Support Year
4
Fiscal Year
2002
Total Cost
$165,355
Indirect Cost
Name
State University of New York at Buffalo
Department
Type
DUNS #
038633251
City
Buffalo
State
NY
Country
United States
Zip Code
14260
Fetoni, Anna R; Bielefeld, Eric C; Paludetti, Gaetano et al. (2014) A putative role of p53 pathway against impulse noise induced damage as demonstrated by protection with pifithrin-alpha and a Src inhibitor. Neurosci Res 81-82:30-7
McNerney, Kathleen M; Burkard, Robert F (2010) The effects of a second stimulus on the auditory steady state response (ASSR) from the inferior colliculus of the chinchilla. Int J Audiol 49:561-73
Cowper-Smith, C D; Dingle, R N; Guo, Y et al. (2010) Synchronous auditory nerve activity in the carboplatin-chinchilla model of auditory neuropathy. J Acoust Soc Am 128:EL56-62
El-Badry, Mohamed M; McFadden, Sandra L (2009) Evaluation of inner hair cell and nerve fiber loss as sufficient pathologies underlying auditory neuropathy. Hear Res 255:84-90
El-Badry, Mohamed M; McFadden, Sandra L (2007) Electrophysiological correlates of progressive sensorineural pathology in carboplatin-treated chinchillas. Brain Res 1134:122-30
Hu, Bo Hua; Henderson, Donald; Nicotera, Thomas M (2006) Extremely rapid induction of outer hair cell apoptosis in the chinchilla cochlea following exposure to impulse noise. Hear Res 211:16-25
Sun, Wei; Mercado 3rd, Eduardo; Wang, Ping et al. (2005) Changes in NMDA receptor expression in auditory cortex after learning. Neurosci Lett 374:63-8
Godfrey, Donald A; Godfrey, Matthew A; Ding, Da-Lian et al. (2005) Amino acid concentrations in chinchilla cochlear nucleus at different times after carboplatin treatment. Hear Res 206:64-73
Bielefeld, Eric C; Hynes, Sarah; Pryznosch, David et al. (2005) A comparison of the protective effects of systemic administration of a pro-glutathione drug and a Src-PTK inhibitor against noise-induced hearing loss. Noise Health 7:24-30
Szalda, Kathleen; Burkard, Robert (2005) The effects of nembutal anesthesia on the auditory steady-state response (ASSR) from the inferior colliculus and auditory cortex of the chinchilla. Hear Res 203:32-44

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