Recording of cochlear bioelectricities from facial nerve canal in rats
YU Jintao
DING Dalian
SUN Hong
Richard Salvi
Abstract：Cochlear bioelectric activities, including endocochlear potential (EP), cochlear microphonics (CM), summat-ing potential (SP) and compound action potential (CAP) originate from different structures and cells of the cochlea. Except for the EP, which is a resting potential mainly reflecting the function of stria vascularis, other cochlear potentials actually are the auditory evoked responses from cochlear sensory hair cells or auditory nerve fibers of spiral ganglion neurons respectively. Therefore, cochlear bioelectric activity recording is an ideal technique to study cochlear physiological functions. Many tradi-tional techniques for cochlear bioelectricity recording through middle ear cavity are not suited for long-term observation due to potential surgical injury or infection to the middle ear. With the expanding use of rats, rat model has been investigated to gain insights into the mechanisms underlying noise or drug-induced hearing loss. However, there lacks effective method for long-term recording of cochlear bioelectricity in rats. A stable long-term recording technique of cochlear potentials in rats is described in this report. A silver electrode was implanted into the horizontal segment of facial nerve canal via stylomastoid fora-men. Since the cochlear cavity is separated from facial nerve canal only by a thin osteal wall, the waveform of cochlear bioelec-tric activities can be easily recorded from within the facial nerve canal. In addition, this electrode insertion does not require opening the middle ear cavity and hence helps avoid surgical damage and infection to the middle ear. The CAP, CM and SP can be reliably recorded following electrode implantation. However, the amplitude of CAP and CM can vary among indivdual animals. This suggests that data analysis is probably more reliable with pre-vs post-treatment design than comparison across animals. In conclusion, electrode insert at the dissepiment of cochlea for recording of cochlear bioelectric activities may pro-vide a useful approach for hearing physiological studies in rats. Moreover, this paper also discusses the characteristics and in-trinsic relationships between different cochlear potentials.
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Publication Date：2014-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：8( 128-135 )