scholarly journals Measuring implanted patient response to tone pips

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Juan M. Cornejo ◽  
Agar K. Quintana ◽  
Nohra E. Beltran ◽  
Pilar Granados
Keyword(s):  
Auditory Nerve ◽  
Dynamic Range ◽  
Test Procedure ◽  
Electrical Potential ◽  
Electrical Current ◽  
Intensity Level ◽  
Electromyographic Activity ◽  
Variable Intensity ◽  
Electrode Current ◽  
Auditory Behavior

Abstract Background An electrical potential not previously reported—electrical cochlear response (ECR)—observed only in implanted patients is described. Its amplitude and growth slope are a measurement of the stimulation achieved by a tone pip on the auditory nerve. The stimulation and recording system constructed for this purpose, the features of this potential obtained in a group of 43 children, and its possible clinical use are described. The ECR is obtained by averaging the EEG epochs acquired each time the cochlear implant (CI) processes a tone pip of known frequency and intensity when the patient is sleeping and using the CI in everyday mode. The ECR is sensitive to tone pip intensity level, microphone sensitivity, sound processor gain, dynamic range of electrical current, and responsiveness to electrical current of the auditory nerve portion involved with the electrode under test. It allows individual evaluation of intracochlear electrodes by choosing, one at the time, the central frequency of the electrode as the test tone pip frequency, so the ECR measurement due to a variable intensity tone pip allows to establish the suitability of the dynamic range of the electrode current. Results There is a difference in ECR measurements when patients are grouped based on their auditory behavior. The ECR slope and amplitude for the Sensitive group is 0.2 μV/dBHL and 10 μV at 50 dBHL compared with 0.04 μV/dBHL and 3 μV at 50dBHL for the Inconsistent group. The clinical cases show that adjusting the dynamic range of current based on the ECR improved the patient’s auditory behavior. Conclusions ECR can be recorded regardless of the artifact due to the electromyographic activity of the patient and the functioning of the CI. Its amplitude and growth slope versus the intensity of the stimulus differs between electrodes. The relationship between minimum ECR detection intensity level and auditory threshold suggests the possibility of estimating patient auditory thresholds this way. ECR does not depend on the subject’s age, cooperation, or health status. It can be obtained at any time after implant surgery and the test procedure is the same regardless of device manufacturer.

Response Properties of Single Auditory Nerve Fibers in the Mouse

2005 ◽  
Vol 93 (1) ◽  
pp. 557-569 ◽  
Author(s):  
Annette M. Taberner ◽  
M. Charles Liberman
Keyword(s):  
Auditory Nerve ◽  
Dynamic Range ◽  
Phase Locking ◽  
Nerve Fibers ◽  
Cochlear Function ◽  
Response Properties ◽  
Tuning Curves ◽  
Rate Versus ◽  
Interstrain Difference ◽  
Mutant Lines

The availability of transgenic and mutant lines makes the mouse a valuable model for study of the inner ear, and a powerful window into cochlear function can be obtained by recordings from single auditory nerve (AN) fibers. This study provides the first systematic description of spontaneous and sound-evoked discharge properties of AN fibers in mouse, specifically in CBA/CaJ and C57BL/6 strains, both commonly used in auditory research. Response properties of 196 AN fibers from CBA/CaJ and 58 from C57BL/6 were analyzed, including spontaneous rates (SR), tuning curves, rate versus level functions, dynamic range, response adaptation, phase-locking, and the relation between SR and these response properties. The only significant interstrain difference was the elevation of high-frequency thresholds in C57BL/6. In general, mouse AN fibers showed similar responses to other mammals: sharpness of tuning increased with characteristic frequency, which ranged from 2.5 to 70 kHz; SRs ranged from 0 to 120 sp/s, and fibers with low SR (<1 sp/s) had higher thresholds, and wider dynamic ranges than fibers with high SR. Dynamic ranges for mouse high-SR fibers were smaller (<20 dB) than those seen in other mammals. Phase-locking was seen for tone frequencies <4 kHz. Maximum synchronization indices were lower than those in cat but similar to those found in guinea pig.

scholarly journals Nonconservative current-induced forces: A physical interpretation

2011 ◽  
Vol 2 ◽  
pp. 727-733 ◽  
Author(s):  
Tchavdar N Todorov ◽  
Daniel Dundas ◽  
Anthony T Paxton ◽  
Andrew P Horsfield
Keyword(s):  
Physical Interpretation ◽  
Current Flow ◽  
Test Procedure ◽  
Electrical Current ◽  
Stimulated Emission ◽  
General Definition ◽  
Noninvasive Test ◽  
Electrical Current Flow ◽  
Definition Of ◽  
A Current

We give a physical interpretation of the recently demonstrated nonconservative nature of interatomic forces in current-carrying nanostructures. We start from the analytical expression for the curl of these forces, and evaluate it for a point defect in a current-carrying system. We obtain a general definition of the capacity of electrical current flow to exert a nonconservative force, and thus do net work around closed paths, by a formal noninvasive test procedure. Second, we show that the gain in atomic kinetic energy over time, generated by nonconservative current-induced forces, is equivalent to the uncompensated stimulated emission of directional phonons. This connection with electron–phonon interactions quantifies explicitly the intuitive notion that nonconservative forces work by angular momentum transfer.

Quantitative Annular Dark Field Electron Microscopy Using Single Electron Signals

2013 ◽  
Vol 20 (1) ◽  
pp. 99-110 ◽  
Author(s):  
Ryo Ishikawa ◽  
Andrew R. Lupini ◽  
Scott D. Findlay ◽  
Stephen J. Pennycook
Keyword(s):  
Electron Microscopy ◽  
Dynamic Range ◽  
Light Element ◽  
Dark Field ◽  
Atomic Scale ◽  
Single Electron ◽  
Single Atom ◽  
Intensity Level ◽  
Primitive Cell ◽  
Annular Dark Field

AbstractOne of the difficulties in analyzing atomic resolution electron microscope images is that the sample thickness is usually unknown or has to be fitted from parameters that are not precisely known. An accurate measure of thickness, ideally on a column-by-column basis, parameter free, and with single atom accuracy, would be of great value for many applications, such as matching to simulations. Here we propose such a quantification method for annular dark field scanning transmission electron microscopy by using the single electron intensity level of the detector. This method has the advantage that we can routinely quantify annular dark field images operating at both low and high beam currents, and under high dynamic range conditions, which is useful for the quantification of ultra-thin or light-element materials. To facilitate atom counting at the atomic scale we use the mean intensity in an annular dark field image averaged over a primitive cell, with no free parameters to be fitted. To illustrate the potential of our method, we demonstrate counting the number of Al (or N) atoms in a wurtzite-type aluminum nitride single crystal at each primitive cell over the range of 3–99 atoms.

scholarly journals Dynamic Range Adaptation to Sound Level Statistics in the Auditory Nerve

2009 ◽  
Vol 29 (44) ◽  
pp. 13797-13808 ◽  
Author(s):  
B. Wen ◽  
G. I. Wang ◽  
I. Dean ◽  
B. Delgutte
Keyword(s):  
Auditory Nerve ◽  
Dynamic Range ◽  
Sound Level ◽  
Level Statistics

Similarity of dynamic range adjustment in auditory nerve and cochlear nuclei

1985 ◽  
Vol 53 (4) ◽  
pp. 940-958 ◽  
Author(s):  
D. J. Gibson ◽  
E. D. Young ◽  
J. A. Costalupes
Keyword(s):  
Auditory Nerve ◽  
Dynamic Range ◽  
Mean Value ◽  
Background Intensity ◽  
Rate Level ◽  
Saturation Intensity ◽  
Type Iv ◽  
Cochlear Nuclei ◽  
The Mean ◽  
Continuous Noise

Rate versus level functions were recorded for responses to best-frequency (BF) tones of 116 cochlear nucleus units and 53 auditory-nerve fibers in the presence of interrupted tone backgrounds and continuous noise backgrounds of various intensities. The backgrounds shifted the dynamic ranges of rate-level functions to higher test intensities, so in the presence of backgrounds, rate saturation occurred at higher intensities than in quiet. The shift in saturation intensity evoked by each background was measured by comparing the rate-level function recorded with the background to one recorded without. The relation between change in saturation intensity and background intensity could be approximated by the formula (formula: see text) delta Isat is the shift in saturation intensity, I is the background intensity, theta is the threshold for evoking shift, and A is the ratio of shift to background intensity re theta. In the appendix, it is shown that A is a measure of a unit's ability to avoid saturation by the background stimulus. The optimal value of A is unity, at which point a unit's operating range is infinite. The value of A depended on BF for interrupted tone backgrounds, but not for continuous noise backgrounds. For BF less than 10 kHz, the mean value of A for tone backgrounds was 0.33 in the auditory nerve, 0.37 in the ventral cochlear nuclei (VCN), and 0.47 in the dorsal cochlear nucleus (DCN). The difference between auditory nerve and VCN was not statistically significant. For BF greater than 10 kHz, the mean A was 0.16 in auditory nerve and 0.30 in VCN. The mean value of A for noise backgrounds was 0.79 in auditory nerve, 0.86 in VCN, 0.86 in DCN units of response types II and III, and 1.04 in DCN type IV units. Only the differences between DCN type IV and the non-DCN unit groups were statistically significant. The qualitative changes produced in rate-level functions by tone and noise backgrounds were similar in auditory nerve and cochlear nuclei except for DCN type IV units. The shifts in rate functions produced by interrupted tone backgrounds did not prevent saturation of the rate response at background intensities above the dynamic range of the unit as recorded in quiet. However, the rate response to test tones was preserved in the presence of all noise background levels used (up to a 30-dB spectrum level). The shift in rate function produced by the noise was almost sufficient to allow the unit to encode test intensity relative to noise background intensity.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of electrical stimulation of the crossed olivocochlear bundle on auditory nerve response to tones in noise

1987 ◽  
Vol 57 (4) ◽  
pp. 1002-1021 ◽  
Author(s):  
R. L. Winslow ◽  
M. B. Sachs
Keyword(s):  
Auditory Nerve ◽  
Noise Level ◽  
Dynamic Range ◽  
Response Rate ◽  
Discharge Rate ◽  
Nerve Fibers ◽  
Range Shift ◽  
Auditory Nerve Fiber ◽  
Auditory Nerve Fibers ◽  
Rate Suppression

The discharge rates of single auditory-nerve fibers responding to best-frequency (BF) tones of varying level presented simultaneously with fixed level broadband noise were recorded with and without electrical stimulation of the crossed olivocochlear bundle (COCB). In the absence of COCB stimulation, monotonic increases in noise level produce monotonic increases in the low-level noise-driven response rate of auditory nerve fibers. As a result of adaptation, these increases in noise-driven response rate produce monotonic decreases in saturation discharge rate. At high noise levels, these compressive effects may eliminate the differential rate response of auditory nerve fibers to BF tones. COCB stimulation can restore this differential rate response by producing large decreases in noise-driven response rate and large increases in saturation discharge rate. In backgrounds of quiet, COCB stimulation is known to shift the dynamic range of single auditory nerve fiber BF tone responses to higher stimulus levels. In the presence of background noise, COCB stimulation produces upward shift of dynamic range, which decreases with increasing noise level. At high noise levels, COCB-induced decompression of rate-level functions may occur with little or no dynamic range shift. This enables auditory nerve fibers to signal changes in tone level with changes in discharge rate at lower signal-to-noise ratios than would be possible otherwise. Broadband noise also produces upward shift of the dynamic range of single auditory nerve fiber BF tone response. Noise-induced dynamic range shift of BF tone response was measured as a function of noise level with and without COCB stimulation. COCB stimulation elevates the threshold of noise-induced dynamic range shift. This shift is thought to result from two-tone rate suppression. Increases in the threshold of noise-induced shift due to COCB stimulation therefore suggests an interaction between the mechanism of two-tone rate suppression and the mechanism by which COCB stimulation produces dynamic range shift. These interactions were further investigated by recording auditory nerve fiber rate responses to fixed-level BF excitor tones presented simultaneously with fixed-frequency variable level suppressor tones. Rate responses were recorded with and without COCB stimulation. Experimental results were quantified using a phenomenological model of two-tone rate suppression presented by Sachs and Abbas.

scholarly journals The Influence of Specimen Size and Distance to a Surface on Resistive Moisture Content Measurements in Wood

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Maria Fredriksson ◽  
Johan Claesson ◽  
Lars Wadsö
Keyword(s):  
Boundary Condition ◽  
Moisture Content ◽  
Electrical Resistance ◽  
Wood Specimen ◽  
Electrical Potential ◽  
Electrical Current ◽  
Specimen Size ◽  
Equivalent Radius ◽  
Measured Moisture Content ◽  
Wood Surfaces

The moisture content of wood is commonly determined by measuring the electrical resistance between two electrodes inserted in the wood. However, problems using this method close to wood surfaces were reported in a previous study. In the present study, the effect of the distance to a surface and the specimen size on the measured electrical resistance was studied analytically as follows. The two electrodes create an electrical potential in the wood specimen. The boundary condition for the electrical potential is that the electrical current across all specimen surfaces is zero, which is achieved by using a suitable array of mirror sources. The analytical solution for the electrical potential was used to analyse the influence of the distance from the electrodes to the specimen surface as well as the size of the specimen. In addition, the error in moisture content was evaluated. The effect of the distance to a surface and the specimen size depended on the equivalent radius of the electrodes; if large electrodes are used in small specimens or close to surfaces, there is a risk that a higher resistance is measured which results in slightly lower measured moisture content than the actual moisture content of the specimen.

Design of the Cochlear Prosthesis: Effects of the Flow of Current in the Implanted Ear

1980 ◽  
Vol 89 (2_suppl) ◽  
pp. 8-10 ◽  
Author(s):  
Francis A. Spelman ◽  
Ben M. Clopton ◽  
Bryan E. Pfingst ◽  
Josef M. Miller
Keyword(s):  
Frequency Dependence ◽  
Temporal Bone ◽  
Current Flow ◽  
Dynamic Range ◽  
Electrical Current ◽  
Electrical Stimulus ◽  
Cochlear Prosthesis ◽  
Excitable Cells ◽  
Electrical Currents ◽  
Threshold Functions

When structures within the temporal bone are stimulated electrically it is desirable to maximize the dynamic range of the stimulus. The maximum dynamic range of electrical stimulus seems to be found when the threshold of stimulation is minimum. The minimum threshold of stimulus is likely to be reached when the electrical current that flows through regions containing excitable cells is maximized. By implanting electrodes throughout the temporal bone, it is possible to apply electrical currents to the ear and to measure the distributions of current flowing within the ear. The results of these measurements demonstrate that when current flow is directed outside the scala tympani, lower thresholds can be obtained. Frequency dependence of the paths of current flow canot be used to explain the frequency dependence of the frequency-threshold functions measured in animals.

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