Manipulation of the Endocochlear Potential Reveals Two Distinct Types of Cochlear Nonlinearity

Strimbu, C. Elliott; Wang, Yi; Olson, Elizabeth S.

doi:10.1016/j.bpj.2020.10.005

Cited by 27 publications

(25 citation statements)

References 65 publications

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“…In the gerbil base, we found motions within the OoC that are substantially different from the motions previously reported (Ren et al, 2016; Ren and He, 2020; He et al, 2018; He and Ren, 2021; Fallah et al, 2019; 2021; Strimbu et al, 2020; Strimbu and Olson, 2021; Cooper et al, 2018). The primary reason for this difference appears to be that we measured from different structures than previous reports and/or used different viewing angles.…”

Section: Discussioncontrasting

confidence: 99%

“…Motion measurements from within the OoC in the gerbil base have been reported by three other groups (Ren et al, 2016;Ren and He, 2020;He et al, 2018;He and Ren, 2021;Fallah et al, 2019;Strimbu et al, 2020;Strimbu and Olson, 2021;. Our measurements differ from previous reports in that: (1) we measured at three transverse locations, i.e., the BM, the OHC-DC-junction and the RL, whereas previous measurements were only at two locations, the BM and in the "OHC region"; and (2) we measured at several locations radially across the OoC at points aligned with the three rows of OHCs.…”

Section: Our Data Compared To Previous Reportsmentioning

confidence: 60%

“…Our measurements present a different and more complex picture of the motion within the OoC than has been conveyed by previously published measurements in the gerbil. We were able to make more-detailed measurements because our OCT system has better spatial resolution than the systems used in previous papers (Ren et al, 2016; Ren and He, 2020; He et al, 2018; He and Ren, 2021; Fallah et al, 2019; 2021; Strimbu et al, 2020; Strimbu and Olson, 2021; Cooper et al, 2018). In previous publications, the OCT images had comparatively lower resolutions, and although one could identify the BM as the first region of reflectivity past the scale, other structures within the OoC could not be identified based on their shapes in the image.…”

Section: Discussionmentioning

confidence: 99%

“…Healthy female Mongolian gerbils, (N=19, aged 5–11 weeks, weight range 41–76 g) were used. Gerbils have the advantage of being small and having been previously used in experiments on intra-cochlear pressure (Olson, 1999, 2001; Kale and Olson, 2015), and in OCT cochlear measurements ( e.g ., Dong et al, 2018; Cooper et al, 2018; Fallah et al, 2019; 2021; Strimbu et al, 2020; Strimbu and Olson, 2021).…”

Section: Methodsmentioning

confidence: 99%

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Motion of the Cochlear Reticular Lamina Varies Radially Across Outer-Hair-Cell Rows

Cho

Puria

2022

Preprint

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The basilar membrane (BM) is connected to the reticular lamina (RL) through three rows of Y-shaped structures consisting of an outer hair cell (OHC) and a Deiters’ cell (DC) with a phalangeal process (PhP) that forms part of the RL mosaic surface. Morphological differences in the anatomy of the Y-shaped structures across the three OHC rows suggest differences in motion across the rows. Here we report OoC transverse motions measured across several radial locations for the gerbil basal region corresponding to ~45 kHz. Cross-sectional imaging and vibrometry measurements were made using a high-resolution (2.23 um axially in water) spectral-domain optical-coherence-tomography (SD-OCT) system. The stimuli were pure tones (2–63 kHz) at ear-canal sound pressure levels (SPLs) of 30–95 dB SPL in anesthetized gerbils (N=9) with healthy cochleae. We report displacements at the RL regions of OHC rows 1–3 (RL1–3), at the OHC-DC junctions of OHC rows 1–3 (OHC-DC-junction1–3), and at the arcuate zone, arcuate-pectinate junction, and pectinate zone of the BM (BMAZ, BMAPJ, and BMPZ, respectively). The in vivo BM displacements showed classic compressive nonlinearity and traveling-wave delays. The RL gain was similar to the BM gain at low frequencies (<20 kHz), but increased with frequency. Near the best frequency (BF), the RL gain was greater than the high-level BM gain by 40 ±5 dB (mean±std), and had greater compressive nonlinearity. RL motion varied radially, and the RL3 gain was significantly greater than that of RL1 by 10 ±1 dB (p<0.001). In contrast, the OHC-DC-junction gain varied little radially across OHCs. At low frequencies the OHC-DC-junction gain was constant across SPLs, and 14 ± 3 dB greater than the BM gain. As the frequency increased, the OHC-DC-junction gain decreased to a level similar to the BM gain at BF. The RL2, 3 phase was advanced by 0.25–0.375 cycles relative to the BM phase at low frequencies, but the RL2, 3 phase lead decreased as the frequency increased, became similar to the BM phase at BF, and lagged behind the BM phase by 0.25–0.5 cycles above BF. The OHC-DC-junction phases were mostly similar to the BM phase at low frequencies, but became delayed relative to the BM as the frequency increased, typically by 0.25–0.5 cycles near BF and by up to 1 cycle above BF. Our results show the most detailed picture of motion around the three OHC rows yet published, indicating that RL motion varied radially. Surprisingly, there was little motion difference across the three OHC rows in the OHC-DC-junction region, indicating that the tops of the DCs move in unison. Our data show a rich array of OoC amplitude and phase variations that are not explained by current theories.

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Section: Discussioncontrasting

confidence: 99%

Section: Our Data Compared To Previous Reportsmentioning

confidence: 60%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Motion of the Cochlear Reticular Lamina Varies Radially Across Outer-Hair-Cell Rows

Cho

Puria

2022

Preprint

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“…To determine whether the sound-evoked response depended on force produced by outer hair cells ( 16 , 17 ), sound-evoked responses were examined after intraperitoneal administration of furosemide (100 mg/kg of body weight), a diuretic known to abolish the positive electrical potential that normally is present near the hearing organ ( 18 ). When this standing potential declines, the electrical gradient across mechanically sensitive ion channels decreases, causing smaller receptor potentials and reduced force production from outer hair cells ( 19 ).…”

Section: Resultsmentioning

confidence: 99%

Best frequencies and temporal delays are similar across the low-frequency regions of the guinea pig cochlea

Burwood¹,

Hakizimana

Nuttall³

et al. 2022

Sci. Adv.

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The cochlea maps tones with different frequencies to distinct anatomical locations. For instance, a faint 5000-hertz tone produces brisk responses at a place approximately 8 millimeters into the 18-millimeter-long guinea pig cochlea, but little response elsewhere. This place code pervades the auditory pathways, where neurons have “best frequencies” determined by their connections to the sensory cells in the hearing organ. However, frequency selectivity in cochlear regions encoding low-frequency sounds has not been systematically studied. Here, we show that low-frequency hearing works according to a unique principle that does not involve a place code. Instead, sound-evoked responses and temporal delays are similar across the low-frequency regions of the cochlea. These findings are a break from theories considered proven for 100 years and have broad implications for understanding information processing in the brainstem and cortex and for optimizing the stimulus delivery in auditory implants.

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The Remarkable Outer Hair Cell: Proceedings of a Symposium in Honour of W. E. Brownell

Ashmore

Oghalai

Dewey

et al. 2023

JARO

Self Cite

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In 1985, Bill Brownell and colleagues published the remarkable observation that cochlear outer hair cells (OHCs) express voltage-driven mechanical motion: electromotility. They proposed OHC electromotility as the mechanism for the elusive "cochlear amplifier" required to explain the sensitivity of mammalian hearing. The finding and hypothesis stimulated an explosion of experiments that have transformed our understanding of cochlear mechanics and physiology, the evolution of hair cell structure and function, and audiology. Here we bring together examples of current research that illustrate the continuing impact of the discovery of OHC electromotility.

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Manipulation of the Endocochlear Potential Reveals Two Distinct Types of Cochlear Nonlinearity

Cited by 27 publications

References 65 publications

Motion of the Cochlear Reticular Lamina Varies Radially Across Outer-Hair-Cell Rows

Motion of the Cochlear Reticular Lamina Varies Radially Across Outer-Hair-Cell Rows

Best frequencies and temporal delays are similar across the low-frequency regions of the guinea pig cochlea

The Remarkable Outer Hair Cell: Proceedings of a Symposium in Honour of W. E. Brownell

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