scholarly journals Rapid mechanical stimulation of inner-ear hair cells by photonic pressure

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Sanjeewa Abeytunge ◽  
Francesco Gianoli ◽  
A James Hudspeth ◽  
Andrei Kozlov
Keyword(s):  
Inner Ear ◽  
Hair Cells ◽  
Dynamic Range ◽  
Auditory Stimuli ◽  
Frequency Range ◽  
Mechanical Vibrations ◽  
Cochlear Hair Cells ◽  
Broad Dynamic Range ◽  
Hair Bundles ◽  
Stimulation Of

Hair cells, the receptors of the inner ear, detect sounds by transducing mechanical vibrations into electrical signals. From the top surface of each hair cell protrudes a mechanical antenna, the hair bundle, which the cell uses to detect and amplify auditory stimuli, thus sharpening frequency selectivity and providing a broad dynamic range. Current methods for mechanically stimulating hair bundles are too slow to encompass the frequency range of mammalian hearing and are plagued by inconsistencies. To overcome these challenges, we have developed a method to move individual hair bundles with photonic force. This technique uses an optical fiber whose tip is tapered to a diameter of a few micrometers and endowed with a ball lens to minimize divergence of the light beam. Here we describe the fabrication, characterization, and application of this optical system and demonstrate the rapid application of photonic force to vestibular and cochlear hair cells.

scholarly journals Rapid mechanical stimulation of inner-ear hair cells by photonic pressure

2021 ◽  
Author(s):  
Sanjeewa Abeytunge ◽  
Francesco Gianoli ◽  
A.J. Hudspeth ◽  
Andrei S. Kozlov
Keyword(s):  
Inner Ear ◽  
Hair Cells ◽  
Dynamic Range ◽  
Auditory Stimuli ◽  
Frequency Range ◽  
Mechanical Vibrations ◽  
Cochlear Hair Cells ◽  
Broad Dynamic Range ◽  
Hair Bundles ◽  
Stimulation Of

AbstractHair cells, the receptors of the inner ear, detect sounds by transducing mechanical vibrations into electrical signals. From the top surface of each hair cell protrudes a mechanical antenna, the hair bundle, which the cell uses to detect and amplify auditory stimuli, thus sharpening frequency selectivity and providing a broad dynamic range. Current methods for mechanically stimulating hair bundles are too slow to encompass the frequency range of mammalian hearing and are plagued by inconsistencies. To overcome these challenges, we have developed a method to move individual hair bundles with photonic force. This technique uses an optical fiber whose tip is tapered to a diameter of a few micrometers and endowed with a ball lens to minimize divergence of the light beam. Here we describe the fabrication, characterization, and application of this optical system and demonstrate the rapid application of photonic force to vestibular and cochlear hair cells.

scholarly journals Generating inner ear organoids containing putative cochlear hair cells from human pluripotent stem cells

2018 ◽  
Vol 9 (9) ◽  
Author(s):  
Minjin Jeong ◽  
Molly O’Reilly ◽  
Nerissa K. Kirkwood ◽  
Jumana Al-Aama ◽  
Majlinda Lako ◽  
...  
Keyword(s):  
Stem Cells ◽  
Inner Ear ◽  
Hair Cells ◽  
Pluripotent Stem Cells ◽  
Human Pluripotent Stem Cells ◽  
Cochlear Hair Cells

scholarly journals Generation of Cochlear Hair Cells from Sox2 Positive Supporting Cells via DNA Demethylation

2020 ◽  
Vol 21 (22) ◽  
pp. 8649
Author(s):  
Xin Deng ◽  
Zhengqing Hu
Keyword(s):  
Transgenic Mice ◽  
Inner Ear ◽  
Hair Cells ◽  
Dna Methyltransferase ◽  
Dna Demethylation ◽  
Egfp Expression ◽  
Supporting Cells ◽  
Cochlear Hair Cells ◽  
Auditory Hair Cells ◽  
Adult Mice

Regeneration of auditory hair cells in adult mammals is challenging. It is also difficult to track the sources of regenerated hair cells, especially in vivo. Previous paper found newly generated hair cells in deafened mouse by injecting a DNA methyltransferase inhibitor 5-azacytidine into the inner ear. This paper aims to investigate the cell sources of new hair cells. Transgenic mice with enhanced green fluorescent protein (EGFP) expression controlled by the Sox2 gene were used in the study. A combination of kanamycin and furosemide was applied to deafen adult mice, which received 4 mM 5-azacytidine injection into the inner ear three days later. Mice were followed for 3, 5, 7 and 14 days after surgery to track hair cell regeneration. Immunostaining of Myosin VIIa and EGFP signals were used to track the fate of Sox2-expressing supporting cells. The results show that (i) expression of EGFP in the transgenic mice colocalized the supporting cells in the organ of Corti, and (ii) the cell source of regenerated hair cells following 5-azacytidine treatment may be supporting cells during 5–7 days post 5-azacytidine injection. In conclusion, 5-azacytidine may promote the conversion of supporting cells to hair cells in chemically deafened adult mice.

scholarly journals Dynamics of mechanically coupled hair-cell bundles of the inner ear

2020 ◽  
Author(s):  
Y. Roongthumskul ◽  
J. Faber ◽  
D. Bozovic
Keyword(s):  
Inner Ear ◽  
Auditory System ◽  
Hair Cells ◽  
Coupled System ◽  
Acoustic Energy ◽  
Hair Bundle ◽  
Free Standing ◽  
Physiological Level ◽  
Mechanical Coupling ◽  
Hair Bundles

ABSTRACTThe high sensitivity and effective frequency discrimination of sound detection performed by the auditory system rely on the dynamics of a system of hair cells. In the inner ear, these acoustic receptors are primarily attached to an overlying structure which provides mechanical coupling between the hair bundles. While the dynamics of individual hair bundles have been extensively investigated, the influence of mechanical coupling on the motility of the system of bundles remains underdetermined. We developed a technique of mechanically coupling two active hair bundles, enabling us to probe the dynamics of the coupled system experimentally. We demonstrated that the coupling could enhance the coherence of hair bundles’ spontaneous oscillation as well as their phase-locked response to sinusoidal stimuli, at the calcium concentration in the surrounding fluid near the physiological level. The empirical data were consistent with numerical results from a model of two coupled nonisochronous oscillators, each displaying a supercritical Hopf bifurcation. The model revealed that weak coupling can poise the system of unstable oscillators closer to the bifurcation by a shift in the critical point. In addition, the dynamics of strongly coupled oscillators far from criticality suggested that individual hair bundles may be regarded as nonisochronous oscillators. An optimal degree of nonisochronicity was required for the observed tuning behavior in the coherence of autonomous motion of the coupled system.STATEMENT OF SIGNIFICANCEHair cells of the inner ear transduce acoustic energy into electrical signals via a deflection of hair bundles. Unlike a passive mechanical antenna, a free-standing hair bundle behaves as an active oscillator that can sustain autonomous oscillations, as well as amplify a low-level stimulus. Hair bundles under physiological conditions are elastically coupled to each other via an extracellular matrix. Therefore, the dynamics of coupled nonlinear oscillators underlie the performance of the peripheral auditory system. Despite extensive theoretical investigations, there are limited experimental evidence that support the significance of coupling on hair bundle motility. We develop a technique to mechanically couple hair bundles and demonstrate the benefits of coupling on hair bundle spontaneous motility.

Effect of Furosemide Upon Morphology of Hair Bundles in Guinea Pig Cochlear Hair Cells

1990 ◽  
Vol 109 (1-2) ◽  
pp. 49-56 ◽  
Author(s):  
S. D. Comis ◽  
M. P. Osborne ◽  
D. J. R. Jeffries
Keyword(s):  
Guinea Pig ◽  
Hair Cells ◽  
Cochlear Hair Cells ◽  
Hair Bundles

A Conceptual Model of Micro Inertial Sensor Mimicking Amplifying Mechanism of the Hair Cells

2006 ◽  
Vol 326-328 ◽  
pp. 827-830
Author(s):  
Ko Eun Lim ◽  
Suk Yung Park
Keyword(s):  
Inner Ear ◽  
Conceptual Model ◽  
Hair Cells ◽  
Dynamic Range ◽  
Inertial Sensor ◽  
High Sensitivity ◽  
Acoustic Vibration ◽  
Operating Conditions ◽  
Negative Stiffness ◽  
Mechanical Stimuli

The inner ear hair cells, the receptors sensing mechanical stimuli such as acoustic vibration and acceleration, achieve remarkably high sensitivity to miniscule stimuli by selectively amplifying small inputs. The gating springs hypothesis proposes that a phenomenon called negative stiffness is responsible for the nonlinear sensitivity. According to the hypothesis, the bundle becomes more sensitive in certain region as its stiffness changes due to the opening or closing of transduction channels, which in turn exert force in the same direction of the bundle’s displacement. In this study, we developed a conceptual model of an inertial sensor inspired by the inner ear hair cells, focusing on the hair cell’s amplifying mechanism known as negative stiffness. The negative stiffness was applied to a simple mass-spring-damper system with nonlinear spring derived from gating springs hypothesis. Sinusoidal stimuli of 0.1Hz~10Hz with magnitude of 1pN to 1000pN were applied to the system to match the dynamic range of vestibular organs. Simulation on this nonlinear model was performed on MATLAB, and power transfers and sensitivities in both transient and steady states were obtained and compared with those from the system with linear spring. Parameters were chosen in relation to those of the hair bundle to reproduce operating conditions of both the hair cells and micro inertial sensors. The suggested model displayed compressive nonlinear sensitivity resulting from selective amplification of smaller stimuli despite the energy loss due to large viscous damping typical in micro systems.

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