Development of an Interface for Across-electrode-channel Stimulation in Nucleus® Cochlear Implant Listeners PDF Download

Author: Covey Ashe Denton
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 296

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Author: Jason Thomas Edwards
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 226

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Author: Lindsay A. DeVries
Publisher:
ISBN:
Category :
Languages : en
Pages : 108

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Book Description
Cochlear implants (CI) are surgically implanted devices that provide sound input to individuals with severe-to-profound hearing loss. While relatively successful, speech understanding abilities are highly variable among implant listeners in both quiet and noisy environments. One source of this variability is the electrode-neuron interface, which refers to how well each electrode activates target auditory neurons. Poor electrode-neuron interfaces may increase channel interaction, which can distort spectral information and result in decreased speech understanding. Electrode position, bone and tissue growth, and the integrity of the auditory neurons are important factors that affect the electrode-neuron interface. Currently, it is not possible to directly measure neural integrity in CI listeners; therefore, obtaining information about electrode position is an alternative approach to assessing the electrode-neuron interface. Information about electrode position is available through computerized tomography (CT) imaging. However, CT imaging is not readily available to audiologists, thus limiting its usefulness in a clinical setting. The purpose of this dissertation work was to examine the relationship between CT-estimated electrode position and two measures of channel interaction: an objective measure, the electrically evoked compound action potential (Experiment 1) and a behavioral measure, the psychophysical tuning curve (Experiment 2). In Experiment 3, we created novel listener strategies based on channels with poor electrode position and excessive channel interaction (based on measures from Experiment 2) in an effort to improve spectral resolution and speech understanding. Results from Experiment 1 and 2 demonstrated that the electrically evoked compound action potential and psychophysical tuning curves, two measures of channel interaction, are correlated with CT-estimates of electrode position. In other words, those electrodes farther from the inner wall of the cochlea tended to exhibit excessive channel interaction with these measures. Results from Experiment 3 suggest that CI listeners can gain improved speech understanding when manipulating channels to compensate for poor electrode position or excessive channel interaction. Importantly, manipulating the "wrong" channels can lead to a detriment in performance. This dissertation work lays the groundwork for assessment of an important aspect of the electrode-neuron interface and the practical application of these measures to CI listener strategies.

Author: Pim van Dijk
Publisher: Springer
ISBN: 331925474X
Category : Medical
Languages : en
Pages : 487

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Book Description
​The International Symposium on Hearing is a prestigious, triennial gathering where world-class scientists present and discuss the most recent advances in the field of human and animal hearing research. The 2015 edition will particularly focus on integrative approaches linking physiological, psychophysical and cognitive aspects of normal and impaired hearing. Like previous editions, the proceedings will contain about 50 chapters ranging from basic to applied research, and of interest to neuroscientists, psychologists, audiologists, engineers, otolaryngologists, and artificial intelligence researchers.​

Author: Fan-Gang Zeng
Publisher: Springer Science & Business Media
ISBN: 1441994343
Category : Medical
Languages : en
Pages : 397

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Book Description
Cochlear implants are currently the standard treatment for profound sensorineural hearing loss. In the last decade, advances in auditory science and technology have not only greatly expanded the utility of electric stimulation to other parts of the auditory nervous system in addition to the cochlea, but have also demonstrated drastic changes in the brain in responses to electric stimulation, including changes in language development and music perception. Volume 20 of SHAR focused on basic science and technology underlying the cochlear implant. However, due to the newness of the ideas and technology, the volume did not cover any emerging applications such as bilateral cochlear implants, combined acoustic-electric stimulation, and other types of auditory prostheses, nor did it review brain plasticity in responses to electric stimulation and its perceptual and language consequences. This proposed volume takes off from Volume 20, and expands the examination of implants into new and highly exciting areas. This edited book starts with an overview and introduction by Dr. Fan-Gang Zeng. Chapters 2-9 cover technological development and the advances in treating the full spectrum of ear disorders in the last ten years. Chapters 10-15 discuss brain responses to electric stimulation and their perceptual impact. This volume is particularly exciting because there have been quantum leap from the traditional technology discussed in Volume 20. Thus, this volume is timely and will be of real importance to the SHAR audience.

Author: Josef M. Miller
Publisher:
ISBN:
Category : Medical
Languages : en
Pages : 448

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Book Description
This volume describes a new direction in technological and biomedical developments for profoundly deaf individuals. The first section covers topics of tissue characteristics, such as responses to electrical stimulation and computer modelling of cochlea currents. Perception of acoustic signals, responses and behavioral pattern as well as psychophysical aspects are treated in the second part. Part III is addressed to perspectives and challenges of encoding schemes. Reports on studies of acoustic and electrical encoding of temporal information, speech features with cochlear implants as well as psychophysical and speech perceptual studies will allow further strategies for cochlea implants.

Author: Aage R. Møller
Publisher: Karger Medical and Scientific Publishers
ISBN: 3805581572
Category : Medical
Languages : en
Pages : 237

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Book Description
Today cochlear implants are the most successful of all prostheses of the nervous system. They are used in individuals who are deaf or suffer from a severe hearing deficiency caused by loss of cochlear hair cells. Auditory brainstem implants provide stimulation of the cochlear nucleus and are used in patients with an auditory nerve dysfunction, a deformed cochlea which does not allow cochlear implantation, or traumatic auditory nerve injury. In this volume different aspects of cochlear implantation such as the role of neural plasticity, the interaction with the development of the auditory system, and the optimal time of implantation in children (sensitive periods) are discussed in detail. Further, the processors and the algorithms used in modern cochlear implants are described The second part is devoted to auditory brainstem implants. It describes surgical techniques, methods for intraoperative testing as well as speech processing. It also deals with electrical stimulation of neural tissue and the neurophysiologic basis for cochlear and brainstem implants. The publication provides the latest scientific and clinical knowledge on cochlear and brainstem implants and is highly recommended to audiologists, otolaryngologists and also neurosurgeons.

Author: Matthew Charles Schoenecker
Publisher:
ISBN:
Category :
Languages : en
Pages : 186

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Book Description
Cochlear implants (CIs) are neural prostheses that currently provide acoustic sensation to more than 120,000 profoundly hearing-impaired people throughout the world. The majority of these CI users are able to understand speech without lip reading and to converse over the telephone. The most fortunate among them can even perform and appreciate music. Unfortunately, however, many CI recipients receive much less benefit from their devices. In order to examine the neuronal bases for these disparate outcomes, a recording system was developed to overcome specific technical limitations in previous studies that recorded neuronal responses to cochlear implant stimulation in animal models. This recording system was then used in two studies comparing responses to normal acoustic stimulation and electrical cochlear implant stimulation in guinea pigs and cats. The design of the recording system included a 32-channel recording amplifier and a software technique for removing stimulus artifacts from recordings of neural responses to high-rate electrical stimulation. Contemporary cochlear implants often deliver current pulse trains with carrier rates of 1000 pulses/s or higher. In neurophysiology studies, this electrical stimulation produces artifacts that are typically much larger than neuronal responses. Therefore, the recording system was specifically designed to record neuronal responses and cancel these electrical stimulus artifacts. When biphasic full-scale-input pulses (1.5-V) are applied directly to the amplifier inputs, each recording channel settles to 20 micro-volts in less than 80 microseconds. This fast recovery makes it likely that the recording electrode-electrolyte interface, not the recording electronics, will limit artifact settling times. Artifacts are blanked in software, allowing flexibility in the choice of blanking period and the possibility of recovering neural data occurring simultaneously with non-saturating artifacts. The system has been used in-vivo to record central neuronal responses to intracochlear electrical stimulation at rates up to 2000 pulses/s. Using this recording system, systematic and quantitative comparisons of inferior-colliculus responses to acoustic stimulation and electrical stimulation in two configurations (monopolar and bipolar) were carried in guinea pigs and cats. Previous cochlear implant studies using isolated electrical stimulus pulses in animal models have reported that monopolar stimulus configurations elicit broad extents of neuronal activation within the central auditory system--much broader than the activation patterns produced by bipolar electrode pairs or acoustic tones. However, psychophysical and speech reception studies that use sustained pulse trains do not show clear performance differences between monopolar and bipolar configurations. To evaluate whether monopolar intracochlear stimulation can produce selective excitation of the inferior colliculus, activation widths were determined along the tonotopic axis of the inferior colliculus for acoustic tones and 1000-pulse/s electrical pulse trains in guinea pigs and cats. Electrical pulse trains were presented using an array of 6-12 stimulating electrodes distributed longitudinally along a space-filling silicone carrier positioned in the scala tympani of the cochlea. The data indicated that for monopolar, bipolar, and acoustic stimuli, activation widths were significantly narrower for sustained responses than for the transient response to the stimulus onset. Furthermore, monopolar and bipolar stimuli elicited similar activation widths when compared at stimulus levels that produced similar peak spike rates. Surprisingly, monopolar and bipolar stimuli produced narrower sustained activation than 60 dB SPL acoustic tones when compared at stimulus levels that produced similar peak spike rates. Therefore, the conclusion from these experiments was that intracochlear electrical stimulation using monopolar pulse trains can produce activation patterns that are at least as selective as bipolar or acoustic stimulation, if stimulus intensities are appropriately matched. The second study compared responses to acoustic and monopolar electrical stimuli that were sinusoidally amplitude modulated (SAM), in order to better model the complex signals delivered by CI processors. For both normal hearing listeners and cochlear implant users, SAM signals produce psychophysical interactions that can extend across large differences in carrier frequency or large intracochlear electrode separations. However, the neural correlates of these phenomena are not well understood. This study was designed to determine whether SAM stimuli elicit activation across a broader extent of the frequency axis of the inferior colliculus than unmodulated steady-state stimuli, and whether this activation is strongly phase locked to the SAM stimulus envelope. To address these questions neuronal activity in the inferior colliculus of guinea pigs, normal cats and chronically deafened cats was recorded in response to acoustic and electrical stimulation. Quantitative analysis of recordings indicated that the extent of inferior colliculus activation was up to 70% broader for SAM stimuli than for unmodulated steady-state stimuli in normal cats and guinea pigs and 160% broader in chronically deafened cats. This activity was also phase-locked to the SAM envelope across a broad extent of the frequency axis of the inferior colliculus. These results suggest that a number of cross-carrier frequency interactions for SAM stimuli could occur at the level of the inferior colliculus. They also show that direct comparisons of responses to acoustic and electrical SAM stimuli can reveal attributes of neural processing that underlie specific psychophysical findings in CI recipients--and thereby can provide a powerful basis for guiding development of new processing strategies for future cochlear implants.

Author: Tania Hanekom
Publisher:
ISBN:
Category :
Languages : en
Pages :

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The objective of this thesis is to provide additional insight into the electrode array-nerve fibre interface that exists in the implanted cochlea and to facilitate investigation of new electrode arrays in interaction with the cochlea and auditory nerve fibres. The focus is on potential distributions and excitation profiles generated by different electrode array types and factors that could have an influence on these distributions and profiles. Research contributions made by the thesis are the creation of a detailed 3-D model of the implanted cochlea that accurately predicts measurable effects in cochlear implant wearers and facilitates effortless simulation of existing and new electrode array variations: the establishment of the important anatomical structures required in a 3-D representation of the implanted cochlea: establishment of evidence that array location is the primary parameter that controls spread of excitation: definition of the critical focussing intensity of intracochlear electrode pairs: confirmation thatmonopolar stimulation could deliver focussed stimulation to approximately the same degree than that delivered by widely spaced electrode configurations and that the use of monopolar configurations over bipolar configurations are therefore advantageous under certain conditions: explanation of the effect that encapsulation tissue around cochlear implant electrodes could have on neural excitation profiles: extension of the information available on the focussing ability of multipolar intracochlear electrode configurations: and establishment of evidence that a higher lateral electrode density could facilitate better focussing of excitation, continuous shaping of excitation profiles and postoperative customization of electrode arrays for individual implant wearers.

Author: Xiaoxiang Zheng
Publisher: Springer Nature
ISBN: 9811320500
Category : Medical
Languages : en
Pages : 250

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Book Description
This book focuses on the frontiers of neural interface technology, including hardware, software, neural decoding and encoding, control systems, and system integration. It also discusses applications for neuroprosthetics, neural diseases and neurorobotics, and the toolkits for basic neuroscience. A neural interface establishes a direct communication channel with the central or peripheral nervous system (CNS or PNS), and enables the nervous system to interact directly with the external devices. Recent advances in neuroscience and engineering are speeding up neural interface technology, paving the way for assisting, augmenting, repairing or restoring sensorimotor and other cognitive functions impaired due to neurological disease or trauma, and so improving the quality of life of those affected. Neural interfaces are now being explored in applications as diverse as rehabilitation, accessibility, gaming, education, recreation, robotics and human enhancement. Neural interfaces also represent a powerful tool to address fundamental questions in neuroscience. Recent decades have witnessed tremendous advances in the field, with a huge impact not only in the development of neuroprosthetics, but also in our basic understanding of brain function. Neural interface technology can be seen as a bridge across the traditional engineering and basic neuroscience. This book provides researchers, graduate and upper undergraduate students from a wide range of disciplines with a cutting-edge and comprehensive summary of neural interface engineering research.