Understanding cochlear function through auditory‐nerve activity: A Zwislocki perspective

2003 ◽  
Vol 113 (4) ◽  
pp. 2249-2249
Author(s):  
Richard A. Schmiedt
Keyword(s):  
Auditory Nerve ◽  
Cochlear Function ◽  
Nerve Activity

Response Properties of Single Auditory Nerve Fibers in the Mouse

2005 ◽  
Vol 93 (1) ◽  
pp. 557-569 ◽  
Author(s):  
Annette M. Taberner ◽  
M. Charles Liberman
Keyword(s):  
Auditory Nerve ◽  
Dynamic Range ◽  
Phase Locking ◽  
Nerve Fibers ◽  
Cochlear Function ◽  
Response Properties ◽  
Tuning Curves ◽  
Rate Versus ◽  
Interstrain Difference ◽  
Mutant Lines

The availability of transgenic and mutant lines makes the mouse a valuable model for study of the inner ear, and a powerful window into cochlear function can be obtained by recordings from single auditory nerve (AN) fibers. This study provides the first systematic description of spontaneous and sound-evoked discharge properties of AN fibers in mouse, specifically in CBA/CaJ and C57BL/6 strains, both commonly used in auditory research. Response properties of 196 AN fibers from CBA/CaJ and 58 from C57BL/6 were analyzed, including spontaneous rates (SR), tuning curves, rate versus level functions, dynamic range, response adaptation, phase-locking, and the relation between SR and these response properties. The only significant interstrain difference was the elevation of high-frequency thresholds in C57BL/6. In general, mouse AN fibers showed similar responses to other mammals: sharpness of tuning increased with characteristic frequency, which ranged from 2.5 to 70 kHz; SRs ranged from 0 to 120 sp/s, and fibers with low SR (<1 sp/s) had higher thresholds, and wider dynamic ranges than fibers with high SR. Dynamic ranges for mouse high-SR fibers were smaller (<20 dB) than those seen in other mammals. Phase-locking was seen for tone frequencies <4 kHz. Maximum synchronization indices were lower than those in cat but similar to those found in guinea pig.

scholarly journals Synaptic Transmission at the Cochlear Nucleus Endbulb Synapse During Age-Related Hearing Loss in Mice

2005 ◽  
Vol 94 (3) ◽  
pp. 1814-1824 ◽  
Author(s):  
Yong Wang ◽  
Paul B. Manis
Keyword(s):  
Hearing Loss ◽  
Synaptic Transmission ◽  
Cochlear Nucleus ◽  
Auditory Nerve ◽  
High Frequency ◽  
Nerve Activity ◽  
Synaptic Release ◽  
Endbulb Of Held ◽  
Age Related ◽  
Age Related Hearing Loss

Age-related hearing loss (AHL) typically starts from high-frequency regions of the cochlea and over time invades lower-frequency regions. During this progressive hearing loss, sound-evoked activity in spiral ganglion cells is reduced. DBA mice have an early onset of AHL. In this study, we examined synaptic transmission at the endbulb of Held synapse between auditory nerve fibers and bushy cells in the anterior ventral cochlear nucleus (AVCN). Synaptic transmission in hearing-impaired high-frequency areas of the AVCN was altered in old DBA mice. The spontaneous miniature excitatory postsynaptic current (mEPSC) frequency was substantially reduced (about 60%), and mEPSCs were significantly slower (about 115%) and smaller (about 70%) in high-frequency regions of old (average age 45 days) DBA mice compared with tonotopically matched regions of young (average age 22 days) DBA mice. Moreover, synaptic release probability was about 30% higher in high-frequency regions of young DBA than that in old DBA mice. Auditory nerve–evoked EPSCs showed less rectification in old DBA mice, suggesting recruitment of GluR2 subunits into the AMPA receptor complex. No similar age-related changes in synaptic release or EPSCs were found in age-matched, normal hearing young and old CBA mice. Taken together, our results suggest that auditory nerve activity plays a critical role in maintaining normal synaptic function at the endbulb of Held synapse after the onset of hearing. Auditory nerve activity regulates both presynaptic (release probability) and postsynaptic (receptor composition and kinetics) function at the endbulb synapse after the onset of hearing.

Electrocochleography

1974 ◽  
Vol 83 (3) ◽  
pp. 312-313
Author(s):  
F. Blair Simmons
Keyword(s):  
Small Group ◽  
Auditory Nerve ◽  
Objective Test ◽  
Clinical Test ◽  
Cochlear Function ◽  
High Frequencies ◽  
Diagnostic Problems

Promontory recording of click-evoked auditory nerve potentials is the most accurate objective test of cochlear function available today. As a truly diagnostic clinical test, however, its use is limited to a small group of problem cases, usually children with multiple diagnostic problems, inasmuch as most hearing losses can be measured in other ways. High frequencies are more accurately measured than those below about 2 kHz.

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