Selective removal of lateral olivocochlear efferents increases vulnerability to acute acoustic injury.
نویسندگان
چکیده
Cochlear sensory cells and neurons receive efferent feedback from the olivocochlear (OC) system. The myelinated medial component of the OC system and its effects on outer hair cells (OHCs) have been implicated in protection from acoustic injury. The unmyelinated lateral (L)OC fibers target ipsilateral cochlear nerve dendrites and pharmacological studies suggest the LOC's dopaminergic component may protect these dendrites from excitotoxic effects of acoustic overexposure. Here, we explore LOC function in vivo by selective stereotaxic destruction of LOC cell bodies in mouse. Lesion success in removing the LOC, and sparing the medial (M)OC, was assessed by histological analysis of brain stem sections and cochlear whole mounts. Auditory brain stem responses (ABRs), a neural-based metric, and distortion product otoacoustic emissions (DPOAEs), an OHC-based metric, were measured in control and surgical mice. In cases where the LOC was at least partially destroyed, there were increases in suprathreshold neural responses that were frequency- and level-independent and not attributable to OHC-based effects. These interaural response asymmetries were not found in controls or in cases where the lesion missed the LOC. In LOC-lesion cases, after exposure to a traumatic stimulus, temporary threshold shifts were greater in the ipsilateral ear, but only when measured in the neural response; OHC-based measurements were always bilaterally symmetric, suggesting OHC vulnerability was unaffected. Interaural asymmetries in threshold shift were not found in either unlesioned controls or in cases that missed the LOC. These findings suggest that the LOC modulates cochlear nerve excitability and protects the cochlea from neural damage in acute acoustic injury.
منابع مشابه
A Role for the Lateral Olivocochlear Neurons in Auditory Function. Focus on “Selective Removal of Lateral Olivocochlear Efferents Increases Vulnerability to Acute Acoustic Injury”
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متن کاملRole for the lateral olivocochlear neurons in auditory function. Focus on "Selective removal of lateral olivocochlear efferents increases vulnerability to acute acoustic injury".
In a paper published in this issue of Journal of Neurophysiology (p. 1775–1785), Darrow and colleagues report that lesions of the lateral superior olive, where the lateral olivocochlear (LOC) efferent originate, enhance auditory evoked potentials in mice. The report also shows that noise-traumatized mouse ears without LOC input are more susceptible to noiseinduced trauma than contralateral ears...
متن کاملRole for the Lateral Olivocochlear Neurons in Auditory Function. Focus on “Selective Removal of Lateral Olivocochlear Efferents Increases Vulnerability to Acute Acoustic Injury”
In a paper published in this issue of Journal of Neurophysiology (p. 1775–1785), Darrow and colleagues report that lesions of the lateral superior olive, where the lateral olivocochlear (LOC) efferent originate, enhance auditory evoked potentials in mice. The report also shows that noise-traumatized mouse ears without LOC input are more susceptible to noiseinduced trauma than contralateral ears...
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عنوان ژورنال:
- Journal of neurophysiology
دوره 97 2 شماره
صفحات -
تاریخ انتشار 2007