Frequency‐dependent self‐induced bias of the basilar membrane and its potential for controlling sensitivity and tuning in the mammalian cochlea

1987 ◽  
Vol 82 (1) ◽  
pp. 139-154 ◽  
Author(s):  
Eric L. LePage
Keyword(s):  
Basilar Membrane ◽  
Frequency Dependent

Electrophysiological Evidence of the Basilar-Membrane Travelling Wave and Frequency Place Coding of Sound in Cochlear Implant Recipients

2017 ◽  
Vol 22 (3) ◽  
pp. 180-189 ◽  
Author(s):  
Luke Campbell ◽  
Christofer Bester ◽  
Claire Iseli ◽  
David Sly ◽  
Adrian Dragovic ◽  
...  
Keyword(s):  
Cochlear Implant ◽  
Direct Evidence ◽  
Basilar Membrane ◽  
Diagnostic Value ◽  
Travelling Wave ◽  
Phase Delay ◽  
Neural Function ◽  
Specific Information ◽  
Auditory Prosthesis ◽  
Frequency Dependent

Aim: To obtain direct evidence for the cochlear travelling wave in humans by performing electrocochleography from within the cochlea in subjects implanted with an auditory prosthesis. Background: Sound induces a travelling wave that propagates along the basilar membrane, exhibiting cochleotopic tuning with a frequency-dependent phase delay. To date, evoked potentials and psychophysical experiments have supported the presence of the travelling wave in humans, but direct measurements have not been made. Methods: Electrical potentials in response to rarefaction and condensation acoustic tone bursts were recorded from multiple sites along the human cochlea, directly from a cochlear implant electrode during, and immediately after, its insertion. These recordings were made from individuals with residual hearing. Results: Electrocochleography was recorded from 11 intracochlear electrodes in 7 ears from 6 subjects, with detectable responses on all electrodes in 5 ears. Cochleotopic tuning and frequency-dependent phase delay of the cochlear microphonic were demonstrated. The response latencies were slightly shorter than those anticipated which we attribute to the subjects' hearing loss. Conclusions: Direct evidence for the travelling wave was observed. Electrocochleography from cochlear implant electrodes provides site-specific information on hair cell and neural function of the cochlea with potential diagnostic value.

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.

Amplitude Distributions of Cochlear Microphonic Response to an Acoustic Sinusoid in Noise

1968 ◽  
Vol 11 (1) ◽  
pp. 63-76
Author(s):  
Donald C. Teas ◽  
Gretchen B. Henry
Keyword(s):  
Small Amplitude ◽  
Basilar Membrane ◽  
Spectral Composition ◽  
Pass Band ◽  
Cochlear Microphonic ◽  
Filter Output ◽  
Electronic Filter ◽  
Low Pass ◽  
Band Pass ◽  
Instantaneous Voltage

The distributions of instantaneous voltage amplitudes in the cochlear microphonic response recorded from a small segment along the basilar membrane are described by computing amplitude histograms. Comparisons are made between the distributions for noise and for those after the addition to the noise of successively stronger sinusoids. The amplitudes of the cochlear microphonic response to 5000 Hz low-pass noise are normally distributed in both Turn I and Turn III of the guinea pig’s cochlea. The spectral composition of the microphonic from Turn I and from Turn III resembles the output of band-pass filters set at about 4000 Hz, and about 500 Hz, respectively. The normal distribution of cochlear microphonic amplitudes for noise is systematically altered by increasing the strength of the added sinusoid. A decrease of three percent in the number of small amplitude events (±1 standard deviation) in the cochlear microphonic from Turn III is seen when the rms voltage of a 500 Hz sinusoid is at −18 dB re the rms voltage of the noise (at the earphone). When the rms of the sinusoid and noise are equal, the decrease in small voltages is about 25%, but there is also an increase in the number of large voltage amplitudes. Histograms were also computed for the output of an electronic filter with a pass-band similar to Turn III of the cochlea. Strong 500 Hz sinusoids showed a greater proportion of large amplitudes in the filter output than in CM III . The data are interpreted in terms of an anatomical substrate.

Preceding Stimulus Frequency-Dependent Potentiation of the Postrest Shortening of the Action Potential Duration in Rabbits.

2000 ◽  
Vol 41 (4) ◽  
pp. 481-492
Author(s):  
Naohiko Takahashi ◽  
Morio Ito ◽  
Shuji Ishida ◽  
Takao Fujino ◽  
Mikiko Nakagawa ◽  
...  
Keyword(s):  
Action Potential ◽  
Action Potential Duration ◽  
Stimulus Frequency ◽  
Frequency Dependent ◽  
Preceding Stimulus

Modeling of Rails Expressed using Pade Approximation Considering Frequency Dependent Effect

2017 ◽  
Vol 137 (2) ◽  
pp. 147-153
Author(s):  
Akinori Hori ◽  
Hiroki Tanaka ◽  
Yuichiro Hayakawa ◽  
Hiroshi Shida ◽  
Keiji Kawahara ◽  
...  
Keyword(s):  
Padé Approximation ◽  
Pade Approximation ◽  
Frequency Dependent ◽  
Dependent Effect
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