TY - JOUR
T1 - The auditory nerve overlapped waveform (ANOW) originates in the cochlear apex
AU - Lichtenhan, J. T.
AU - Hartsock, J. J.
AU - Gill, R. M.
AU - Guinan, J. J.
AU - Salt, A. N.
N1 - Funding Information:
We thank Doctors Ann E. Hickox, Mark A. Rutherford, Christopher A. Shera, and Mrs. Uzma S. Wilson for helpful discussion on this research. Two anonymous reviewers and Associate Editor Dr. Nigel Cooper provided productive criticisms that improved this report. This work was supported by grants R03 DC012844 (J.T.L.), R01 DC000235 (J.J.G.), and R01 DC001368 (A.N.S.) from the National Institutes of Health, National Institute on Deafness and Other Communication Disorders.
PY - 2014/6
Y1 - 2014/6
N2 - Measurements of cochlear function with compound action potentials (CAPs), auditory brainstem responses, and otoacoustic emissions work well with high-frequency sounds but are problematic at low frequencies. We have recently shown that the auditory nerve overlapped waveform (ANOW) can objectively quantify low-frequency (<1 kHz) auditory sensitivity, as thresholds for ANOW at low frequencies and for CAP at high frequencies relate similarly to single auditory nerve fiber thresholds. This favorable relationship, however, does not necessarily mean that ANOW originates from auditory nerve fibers innervating low-frequency regions of the cochlear apex. In the present study, we recorded the cochlear response to tone bursts of low frequency (353, 500, and 707 Hz) and high frequency (2 to 16 kHz) during administration of tetrodotoxin (TTX) to block neural function. TTX was injected using a novel method of slow administration from a pipette sealed into the cochlear apex, allowing real-time measurements of systematic neural blocking from apex to base. The amplitude of phase-locked (ANOW) and onset (CAP) neural firing to moderate-level, low-frequency sounds were markedly suppressed before thresholds and responses to moderate-level, high-frequency sounds were affected. These results demonstrate that the ANOW originates from responses of auditory nerve fibers innervating cochlear apex, confirming that ANOW provides a valid physiological measure of low-frequency auditory nerve function.
AB - Measurements of cochlear function with compound action potentials (CAPs), auditory brainstem responses, and otoacoustic emissions work well with high-frequency sounds but are problematic at low frequencies. We have recently shown that the auditory nerve overlapped waveform (ANOW) can objectively quantify low-frequency (<1 kHz) auditory sensitivity, as thresholds for ANOW at low frequencies and for CAP at high frequencies relate similarly to single auditory nerve fiber thresholds. This favorable relationship, however, does not necessarily mean that ANOW originates from auditory nerve fibers innervating low-frequency regions of the cochlear apex. In the present study, we recorded the cochlear response to tone bursts of low frequency (353, 500, and 707 Hz) and high frequency (2 to 16 kHz) during administration of tetrodotoxin (TTX) to block neural function. TTX was injected using a novel method of slow administration from a pipette sealed into the cochlear apex, allowing real-time measurements of systematic neural blocking from apex to base. The amplitude of phase-locked (ANOW) and onset (CAP) neural firing to moderate-level, low-frequency sounds were markedly suppressed before thresholds and responses to moderate-level, high-frequency sounds were affected. These results demonstrate that the ANOW originates from responses of auditory nerve fibers innervating cochlear apex, confirming that ANOW provides a valid physiological measure of low-frequency auditory nerve function.
KW - Auditory nerve neurophonic
KW - Compound action potential
KW - Low-frequency hearing
KW - Neural synchrony
KW - Phase locking
UR - http://www.scopus.com/inward/record.url?scp=84904597018&partnerID=8YFLogxK
U2 - 10.1007/s10162-014-0447-y
DO - 10.1007/s10162-014-0447-y
M3 - Article
C2 - 24515339
AN - SCOPUS:84904597018
SN - 1525-3961
VL - 15
SP - 395
EP - 411
JO - JARO - Journal of the Association for Research in Otolaryngology
JF - JARO - Journal of the Association for Research in Otolaryngology
IS - 3
ER -