scholarly journals Noninvasive in vivo imaging reveals differences between tectorial membrane and basilar membrane traveling waves in the mouse cochlea

2015 ◽  
Vol 112 (10) ◽  
pp. 3128-3133 ◽  
Author(s):  
Hee Yoon Lee ◽  
Patrick D. Raphael ◽  
Jesung Park ◽  
Audrey K. Ellerbee ◽  
Brian E. Applegate ◽  
...  
Keyword(s):  
Traveling Waves ◽  
Traveling Wave ◽  
Basilar Membrane ◽  
Frequency Tuning ◽  
Tectorial Membrane ◽  
Inner Hair Cell ◽  
Auditory Response ◽  
3D Volume ◽  
Membrane Vibration

Sound is encoded within the auditory portion of the inner ear, the cochlea, after propagating down its length as a traveling wave. For over half a century, vibratory measurements to study cochlear traveling waves have been made using invasive approaches such as laser Doppler vibrometry. Although these studies have provided critical information regarding the nonlinear processes within the living cochlea that increase the amplitude of vibration and sharpen frequency tuning, the data have typically been limited to point measurements of basilar membrane vibration. In addition, opening the cochlea may alter its function and affect the findings. Here we describe volumetric optical coherence tomography vibrometry, a technique that overcomes these limitations by providing depth-resolved displacement measurements at 200 kHz inside a 3D volume of tissue with picometer sensitivity. We studied the mouse cochlea by imaging noninvasively through the surrounding bone to measure sound-induced vibrations of the sensory structures in vivo, and report, to our knowledge, the first measures of tectorial membrane vibration within the unopened cochlea. We found that the tectorial membrane sustains traveling wave propagation. Compared with basilar membrane traveling waves, tectorial membrane traveling waves have larger dynamic ranges, sharper frequency tuning, and apically shifted positions of peak vibration. These findings explain discrepancies between previously published basilar membrane vibration and auditory nerve single unit data. Because the tectorial membrane directly overlies the inner hair cell stereociliary bundles, these data provide the most accurate characterization of the stimulus shaping the afferent auditory response available to date.

scholarly journals Hydromechanical Structure of the Cochlea Supports the Backward Traveling Wave in the Cochlea In Vivo

2018 ◽  
Vol 2018 ◽  
pp. 1-11
Author(s):  
Fangyi Chen ◽  
Dingjun Zha ◽  
Xiaojie Yang ◽  
Allyn Hubbard ◽  
Alfred Nuttall
Keyword(s):  
Traveling Wave ◽  
Basilar Membrane ◽  
Wave Theory ◽  
Otoacoustic Emission ◽  
Traditional Theory ◽  
Vibration Source ◽  
Ear Canal ◽  
Local Vibration ◽  
Membrane Vibration

The discovery that an apparent forward-propagating otoacoustic emission (OAE) induced basilar membrane vibration has created a serious debate in the field of cochlear mechanics. The traditional theory predicts that OAE will propagate to the ear canal via a backward traveling wave on the basilar membrane, while the opponent theory proposed that the OAE will reach the ear canal via a compression wave. Although accepted by most people, the basic phenomenon of the backward traveling wave theory has not been experimentally demonstrated. In this study, for the first time, we showed the backward traveling wave by measuring the phase spectra of the basilar membrane vibration at multiple longitudinal locations of the basal turn of the cochlea. A local vibration source with a unique and precise location on the cochlear partition was created to avoid the ambiguity of the vibration source in most previous studies. We also measured the vibration pattern at different places of a mechanical cochlear model. A slow backward traveling wave pattern was demonstrated by the time-domain sequence of the measured data. In addition to the wave propagation study, a transmission line mathematical model was used to interpret why no tonotopicity was observed in the backward traveling wave.

scholarly journals Imaging forward and Reverse Traveling Waves in the Cochlea

2018 ◽  
Author(s):  
A. Zosuls ◽  
L. C. Rupprecht ◽  
D. C. Mountain
Keyword(s):  
Hair Cell ◽  
Traveling Waves ◽  
Traveling Wave ◽  
Otoacoustic Emissions ◽  
Basilar Membrane ◽  
Full Potential ◽  
Inner Hair Cell ◽  
Probe Location ◽  
Cochlear Partition ◽  
Wave Modes

AbstractThe presence of forward and reverse traveling wave modes on the basilar membrane has important implications to how the cochlea functions as a filter, transducer, and amplifier of sound. The presence and parameters of traveling waves are of particular importance to interpreting otoacoustic emissions (OAE). OAE are vibrations that propagate out of the cochlea and are measureable as sounds emitted from the tympanic membrane. The interpretation of OAE is a powerful research and clinical diagnostic tool, but OAE use has not reached full potential because the mechanisms of their generation and propagation are not fully understood. Of particular interest and deliberation is whether the emissions propagate as a fluid compression wave or a structural traveling wave. In this study a mechanical probe was used to simulate an OAE generation site and optical imaging was used to measure displacement of the inner hair cell stereocilia of the gerbil cochlea. Inner hair cell stereocilia displacement measurements were made in the radial dimension as a function of their longitudinal location along the length of the basilar membrane in response to a transverse stimulation from the probe. The analysis of the spatial frequency response of the inner hair cell stereocilia at frequencies near the characteristic frequency (CF) of the measurement location suggests that a traveling wave propagates in the cochlear partition simultaneously basal and apical (forward and reverse) from the probe location. The traveling wave velocity was estimated to be 5.9m/s - 8m/s in the base (near CF of 29kHz - 40kHz) and 1.9m/s - 2.4m/s in the second turn (near CF of 2kHz - 3kHz). These results suggest that the cochlear partition is capable of supporting both forward and reverse traveling wave modes generated by a source driving the basilar membrane. This suggests that traveling waves in the cochlear partition contribute to OAE propagation.

scholarly journals Direct Visualization of Organ of Corti Kinematics in a Hemicochlea

1999 ◽  
Vol 82 (5) ◽  
pp. 2798-2807 ◽  
Author(s):  
Xintian Hu ◽  
Burt N. Evans ◽  
Peter Dallos
Keyword(s):  
Hair Cell ◽  
Hair Cells ◽  
Basilar Membrane ◽  
Mechanical Vibration ◽  
Cell Receptor ◽  
Outer Hair Cells ◽  
Tectorial Membrane ◽  
Low Frequencies ◽  
Geometric Models ◽  
Membrane Vibration

The basilar membrane in the mammalian cochlea vibrates when the cochlea receives a sound stimulus. This mechanical vibration is transduced into hair cell receptor potentials and thereafter encoded by action potentials in the auditory nerve. Knowledge of the mechanical transformation that converts basilar membrane vibration into hair cell stimulation has been limited, until recently, to hypothetical geometric models. Experimental observations are largely lacking to prove or disprove the validity of these models. We have developed a hemicochlea preparation to visualize the kinematics of the cochlear micromechanism. Direct mechanical drive of 1–2 Hz sinusoidal command was applied to the basilar membrane. Vibration patterns of the basilar membrane, inner and outer hair cells, supporting cells, and tectorial membrane have been recorded concurrently by means of a video optical flow technique. Basilar membrane vibration was driven in a direction transversal to its plane. However, the direction of the resulting vibration was found to be essentially radial at the level of the reticular lamina and cuticular plates of inner and outer hair cells. The tectorial membrane vibration was mainly transversal. The transmission ratio between cilia displacement of inner and outer hair cells and basilar membrane vibration is in the range of 0.7–1.1. These observations support, in part, the classical geometric models at low frequencies. However, there appears to be less tectorial membrane motion than predicted, and it is largely in the transversal direction.

Traveling Waves Demonstrated by a Revolving Helix

1979 ◽  
Vol 88 (6) ◽  
pp. 768-770
Author(s):  
Luis D. Benítez
Keyword(s):  
Experimental Data ◽  
Traveling Waves ◽  
Traveling Wave ◽  
Basilar Membrane ◽  
Simple Procedure ◽  
Peak Amplitude ◽  
Phase Lag ◽  
Teaching Laboratory ◽  
Membrane Oscillations ◽  
Frequency Of Stimulation

A simple procedure for the demonstration of traveling waves in actual morion in the classroom is described. Using a matched set of experimental data on a) peak amplitude of basilar membrane oscillations, and b) phase-lag along the membrane, both for a given frequency of stimulation, it is possible to construct a solid spiral, or helix, of constantly changing diameter and pitch. When projected on a screen, the helix will look like a longitudinal amplitude gradient along the basilar membrane; as the helix is rotated, the projection will appear as a traveling wave. It is suggested that the device, because of its inherent simplicity, is a useful aid in a teaching laboratory for future otolaryngologists, audiologists and other professionals related to the field of hearing.

scholarly journals Micromotor Manipulation Using Ultrasonic Active Traveling Waves

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 192
Author(s):  
Hiep Xuan Cao ◽  
Daewon Jung ◽  
Han-Sol Lee ◽  
Gwangjun Go ◽  
Minghui Nan ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Traveling Waves ◽  
Traveling Wave ◽  
Ex Vivo ◽  
Ultrasonic Transducer ◽  
Acoustic Streaming ◽  
Versatile Tool ◽  
Ultrasonic Manipulation

The ability to manipulate therapeutic agents in fluids is of interest to improve the efficiency of targeted drug delivery. Ultrasonic manipulation has great potential in the field of therapeutic applications as it can trap and manipulate micro-scale objects. Recently, several methods of ultrasonic manipulation have been studied through standing wave, traveling wave, and acoustic streaming. Among them, the traveling wave based ultrasonic manipulation is showing more advantage for in vivo environments. In this paper, we present a novel ultrasonic transducer (UT) array with a hemispherical arrangement that generates active traveling waves with phase modulation to manipulate a micromotor in water. The feasibility of the method could be demonstrated by in vitro and ex vivo experiments conducted using a UT array with 16 transducers operating at 1 MHz. The phase of each transducer was controlled independently for generating a twin trap and manipulation of a micromotor in 3D space. This study shows that the ultrasonic manipulation device using active traveling waves is a versatile tool that can be used for precise manipulation of a micromotor inserted in a human body and targeted for drug delivery.

scholarly journals On the Molecular Filters in Cochlea Transduction

2018 ◽  
Vol 10 (4) ◽  
pp. 48
Author(s):  
Valeri Goussev
Keyword(s):  
Hair Cells ◽  
Feedback Loop ◽  
Basilar Membrane ◽  
Automatic Gain Control ◽  
Gain Control ◽  
Outer Hair Cells ◽  
Tectorial Membrane ◽  
Inner Hair Cell ◽  
Perception Threshold ◽  
Spatially Distributed

The article is devoted to the specific consideration of the cochlear transduction for the low level sound intensities, which correspond to the regions near the perception threshold. The basic cochlea mechanics is extended by the new concept of the molecular filters, which allows discussing the transduction mechanism on the molecular level in the space-time domain. The molecular filters are supposed to be built on the set of the stereocilia of every inner hair cell. It is hypothesized that the molecular filters are the sensors in the feedback loop, which includes also outer hair cells along with the tectorial membrane and uses the zero compensation method to evaluate the traveling wave shape on the basilar membrane. Besides the compensation, the feedback loop, being spatially distributed along the cochlea, takes control over the tectorial membrane strain field generated by the outer hair cells, and implements it as the mechanism for the automatic gain control in the sound transduction.

scholarly journals On the molecular filters in cochlea transduction

2018 ◽  
Author(s):  
Valeri Goussev
Keyword(s):  
Hair Cells ◽  
Feedback Loop ◽  
Basilar Membrane ◽  
Automatic Gain Control ◽  
Gain Control ◽  
Outer Hair Cells ◽  
Tectorial Membrane ◽  
Inner Hair Cell ◽  
Perception Threshold ◽  
Spatially Distributed

AbstractThe article is devoted to the specific consideration of the cochlear transduction for the low level sound intensities, which correspond to the regions near the perception threshold. The basic cochlea mechanics is extended by the new concept of the molecular filters, which allows us to discuss the transduction mechanism on the molecular level in the space-time domain. The molecular filters are supposed to be built on the set of the stereocilia of every inner hair cell. It is hypothesized that the molecular filters are the sensors in the feedback loop, which includes also outer hair cells along with the tectorial membrane and uses the zero compensation method to evaluate the traveling wave shape on the basilar membrane. Besides the compensation, the feedback loop, being spatially distributed along the cochlea, takes control over the tectorial membrane strain field generated by the outer hair cells, and implements it as the mechanism for the automatic gain control in the sound transduction.

A technique for protecting delicate specimens during processing

1989 ◽  
Vol 47 ◽  
pp. 982-983
Author(s):  
R.J. Mount ◽  
R.V. Harrison
Keyword(s):  
Basilar Membrane ◽  
Low Cost ◽  
Organ Of Corti ◽  
Region Of Interest ◽  
Sensory Epithelium ◽  
Physical Damage ◽  
Air Drying ◽  
Specimen Handling ◽  
Two Component

The sensory end organ of the ear, the organ of Corti, rests on a thin basilar membrane which lies between the bone of the central modiolus and the bony wall of the cochlea. In vivo, the organ of Corti is protected by the bony wall which totally surrounds it. In order to examine the sensory epithelium by scanning electron microscopy it is necessary to dissect away the protective bone and expose the region of interest (Fig. 1). This leaves the fragile organ of Corti susceptible to physical damage during subsequent handling. In our laboratory cochlear specimens, after dissection, are routinely prepared by the O-T- O-T-O technique, critical point dried and then lightly sputter coated with gold. This processing involves considerable specimen handling including several hours on a rotator during which the organ of Corti is at risk of being physically damaged. The following procedure uses low cost, readily available materials to hold the specimen during processing ,preventing physical damage while allowing an unhindered exchange of fluids.Following fixation, the cochlea is dehydrated to 70% ethanol then dissected under ethanol to prevent air drying. The holder is prepared by punching a hole in the flexible snap cap of a Wheaton vial with a paper hole punch. A small amount of two component epoxy putty is well mixed then pushed through the hole in the cap. The putty on the inner cap is formed into a “cup” to hold the specimen (Fig. 2), the putty on the outside is smoothed into a “button” to give good attachment even when the cap is flexed during handling (Fig. 3). The cap is submerged in the 70% ethanol, the bone at the base of the cochlea is seated into the cup and the sides of the cup squeezed with forceps to grip it (Fig.4). Several types of epoxy putty have been tried, most are either soluble in ethanol to some degree or do not set in ethanol. The only putty we find successful is “DUROtm MASTERMENDtm Epoxy Extra Strength Ribbon” (Loctite Corp., Cleveland, Ohio), this is a blue and yellow ribbon which is kneaded to form a green putty, it is available at many hardware stores.

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