Dimensions of the Scala Tympani in the Human and Cat with Reference to Cochlear Implants

Hatsushika, Shin-Ichi; Shepherd, Robert K.; Tong, Y. C.; Clark, Graeme M.; Funasaka, Sotaro

doi:10.1177/000348949009901104

Cited by 92 publications

(50 citation statements)

References 11 publications

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“…Computational modeling approaches may prove particularly useful in addressing longstanding issues of across-species differences in cochlear or nerve-fiber anatomy (Hatsushika et al 1990;Nadol et al 1990;Felix 2002) that could render some of our results inapplicable to the physiology of electrically stimulated human ANFs. For example, while feline and human cochleae are similar, they vary in gross dimensions and shape of the first turn.…”

Section: Discussionmentioning

confidence: 99%

Changes Across Time in the Temporal Responses of Auditory Nerve Fibers Stimulated by Electric Pulse Trains

Miller

Zhang

et al. 2008

JARO

105

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Most auditory prostheses use modulated electric pulse trains to excite the auditory nerve. There are, however, scant data regarding the effects of pulse trains on auditory nerve fiber (ANF) responses across the duration of such stimuli. We examined how temporal ANF properties changed with level and pulse rate across 300-ms pulse trains. Four measures were examined: (1) first-spike latency, (2) interspike interval (ISI), (3) vector strength (VS), and (4) Fano factor (FF, an index of the temporal variability of responsiveness). Data were obtained using 250-, 1,000-, and 5,000-pulse/s stimuli. First-spike latency decreased with increasing spike rate, with relatively small decrements observed for 5,000-pulse/s trains, presumably reflecting integration. ISIs to low-rate (250 pulse/s) trains were strongly locked to the stimuli, whereas ISIs evoked with 5,000-pulse/s trains were dominated by refractory and adaptation effects. Across time, VS decreased for low-rate trains but not for 5,000-pulse/s stimuli. At relatively high spike rates (9200 spike/s), VS values for 5,000-pulse/s trains were lower than those obtained with 250-pulse/s stimuli (even after accounting for the smaller periods of the 5,000-pulse/s stimuli), indicating a desynchronizing effect of high-rate stimuli. FF measures also indicated a desynchronizing effect of high-rate trains. Across a wide range of response rates, FF underwent relatively fast increases (i.e., within 100 ms) for 5,000-pulse/s stimuli. With a few exceptions, ISI, VS, and FF measures approached asymptotic values within the 300-ms duration of the low-and high-rate trains. These findings may have implications for designs of cochlear implant stimulus protocols, understanding electrically evoked compound action potentials, and interpretation of neural measures obtained at central nuclei, which depend on understanding the output of the auditory nerve.

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Section: Discussionmentioning

confidence: 99%

Changes Across Time in the Temporal Responses of Auditory Nerve Fibers Stimulated by Electric Pulse Trains

Miller

Zhang

et al. 2008

JARO

105

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“…1 and 2). 1 The cochlea model is constructed according to our early work, 7 and is adapted to the dimension of scala tympani based on the study of Hatsuchika et al 12 The modeled cochlea is embedded in a bone, which is not shown in the figure, to form the complete model. Although the structure of a real cochlea is spiral and tapering, the basal turn, especially for the first half turn, is close to a circular shape with a similar dimension.…”

Section: Model Of the Human Cochlea And Analysis Approachmentioning

confidence: 99%

Conditions for Generating Virtual Channels in Cochlear Prosthesis Systems

Choi

Hsu

2008

Ann Biomed Eng

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Abstract-Simultaneous electrical stimulation of neighboring electrodes in cochlear prosthesis systems generates channel interaction. However, intermediate channels, or virtual channels between the neighboring electrodes can be created through controlled channel interaction. This effect may be exploited for sending new information to the hearing nerves by stimulating in a suitable manner. The actual stimulation sites are therefore not limited to the number of electrodes. Clinical experiments, however, show that virtual channels are not always perceived. In this paper, electrical simulation with finite element analysis on a half turn human cochlea model is adopted to model the virtual channel effect, and the conditions for generating virtual channels are discussed. Five input current ratios (100/0, 70/30, 50/50, 30/70, 0/100) are applied to generate virtual channels. Three electrode arrays parameters are taken into consideration: distance between electrode contact and modiolus, spacing between adjacent electrode contacts and scale of electrode contact size. By observing the activating function contours, the virtual channel patterns and performances can be measured and examined. The results showed that a broad excitation pattern is necessary to produce the kind of electrode interaction that can form distinct virtual channels.

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“…Methods using several type of plastic casts have been widely employed to evaluate the dimensions of cochlear anatomy (Zrunek et al, 1980;Zrunek and Lischka, 1981;Dimopoulos and Muren, 1990;Hatsushika et al, 1990;Wysocki, 1999;Erixon et al, 2009;RaskAndersen et al, 2011), but they do not allow accurate preservation of the geometric relationships of fragile cochlear structures and artifact-free measurements. Microdissections enable measurements of basic external dimensions of the cochlea like the width of the cochlear base (Wright and Roland, 2005), but as plastic casts, it cannot provide detailed three-dimensional reconstruction.…”

Section: Introductionmentioning

confidence: 99%

Automated analysis of human cochlea shape variability from segmented μ CT images

Demarcy

Vandersteen

Guevara³

et al. 2017

Computerized Medical Imaging and Graphics

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The aim of this study is to define an automated and reproducible framework for cochlear anatomical analysis from high-resolution segmented images and to provide a comprehensive and objective shape variability study suitable for cochlear implant design and surgery planning. For the scala tympani (ST), the scala vestibuli (SV) and the whole cochlea, the variability of the arc lengths and the radial and longitudinal components of the lateral, central and modiolar paths are studied. The robustness of the automated cochlear coordinate system estimation is validated with synthetic and real data. Cochlear cross-sections are statistically analyzed using area, height and width measurements. The cross-section tilt angle is objectively measured and this data documents a significant feature for occurrence of surgical trauma.

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Dimensions of the Scala Tympani in the Human and Cat with Reference to Cochlear Implants

Cited by 92 publications

References 11 publications

Changes Across Time in the Temporal Responses of Auditory Nerve Fibers Stimulated by Electric Pulse Trains

Changes Across Time in the Temporal Responses of Auditory Nerve Fibers Stimulated by Electric Pulse Trains

Conditions for Generating Virtual Channels in Cochlear Prosthesis Systems

Automated analysis of human cochlea shape variability from segmented μ CT images

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