TY - JOUR
T1 - Noise-Induced loudness recruitment and hyperacusis
T2 - Insufficient central gain in auditory cortex and amygdala
AU - Radziwon, Kelly
AU - Auerbach, Benjamin D.
AU - Ding, Dalian
AU - Liu, Xiaopeng
AU - Chen, Guang Di
AU - Salvi, Richard
N1 - Funding Information:
This work was supported by NIH grants to BA (F32DC015160) and RS (R01DC014693).
Publisher Copyright:
© 2019 IBRO
Copyright:
Copyright 2019 Elsevier B.V., All rights reserved.
PY - 2019/12/1
Y1 - 2019/12/1
N2 - Noise-induced hearing loss generally induces loudness recruitment, but sometimes gives rise to hyperacusis, a debilitating condition in which moderate intensity sounds are perceived abnormally loud. In an attempt to develop an animal model of loudness hyperacusis, we exposed rats to a 16–20 kHz noise at 104 dB SPL for 12 weeks. Behavioral reaction time-intensity functions were used to assess loudness growth functions before, during and 2-months post-exposure. During the exposure, loudness recruitment (R) was present in the region of hearing loss, but subtle evidence of hyperacusis (H) started to emerge at the border of the hearing loss. Unexpectedly, robust evidence of hyperacusis appeared below and near the edge of the hearing loss 2-months post-exposure. To identify the neural correlates of hyperacusis and test the central gain model of hyperacusis, we recorded population neural responses from the cochlea, auditory cortex and lateral amygdala 2-months post-exposure. Compared to controls, the neural output of the cochlea was greatly reduced in the noise group. Consistent with central gain models, the gross neural responses from the auditory cortex and amygdala were proportionately much larger than those from the cochlea. However, despite central amplification, the population responses in the auditory cortex and amygdala were still below the level needed to fully account for hyperacusis and/or recruitment. Having developed procedures that can consistently induce hyperacusis in rats, our results set the stage for future studies that seek to identify the neurobiological events that give rise to hyperacusis and to develop new therapies to treat this debilitating condition.
AB - Noise-induced hearing loss generally induces loudness recruitment, but sometimes gives rise to hyperacusis, a debilitating condition in which moderate intensity sounds are perceived abnormally loud. In an attempt to develop an animal model of loudness hyperacusis, we exposed rats to a 16–20 kHz noise at 104 dB SPL for 12 weeks. Behavioral reaction time-intensity functions were used to assess loudness growth functions before, during and 2-months post-exposure. During the exposure, loudness recruitment (R) was present in the region of hearing loss, but subtle evidence of hyperacusis (H) started to emerge at the border of the hearing loss. Unexpectedly, robust evidence of hyperacusis appeared below and near the edge of the hearing loss 2-months post-exposure. To identify the neural correlates of hyperacusis and test the central gain model of hyperacusis, we recorded population neural responses from the cochlea, auditory cortex and lateral amygdala 2-months post-exposure. Compared to controls, the neural output of the cochlea was greatly reduced in the noise group. Consistent with central gain models, the gross neural responses from the auditory cortex and amygdala were proportionately much larger than those from the cochlea. However, despite central amplification, the population responses in the auditory cortex and amygdala were still below the level needed to fully account for hyperacusis and/or recruitment. Having developed procedures that can consistently induce hyperacusis in rats, our results set the stage for future studies that seek to identify the neurobiological events that give rise to hyperacusis and to develop new therapies to treat this debilitating condition.
KW - Amygdala
KW - Auditory cortex
KW - Central gain
KW - Hyperacusis
KW - Loudness recruitment
KW - Noise exposure
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U2 - 10.1016/j.neuroscience.2019.09.010
DO - 10.1016/j.neuroscience.2019.09.010
M3 - Article
C2 - 31669363
AN - SCOPUS:85075388850
SN - 0306-4522
VL - 422
SP - 212
EP - 227
JO - Neuroscience
JF - Neuroscience
ER -