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Author: Tania Hanekom Publisher: ISBN: Category : Languages : en Pages :
Book Description
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: Joseph M. Miller Publisher: Springer ISBN: 9781461279365 Category : Medical Languages : en Pages : 0
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: Fan-Gang Zeng Publisher: Springer ISBN: 9781441923462 Category : Science Languages : en Pages : 438
Book Description
Cochlear implants have instigated a popular but controversial revolution in the treatment of deafness. This book discusses the physiological bases of using artificial devices to electrically stimulate the brain to interpret sounds. As the first successful device to restore neural function, the cochlear implant serves as a model for research in neuroscience and biomedical engineering. These and other auditory prostheses are discussed in the context of historical treatments, engineering, psychophysics and clinical issues as well as implications for speech, behavior, cognition and long-term effects on people.
Author: Tania Hanekom Publisher: ISBN: Category : Languages : en Pages :
Book Description
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: Fan-Gang Zeng Publisher: Springer Science & Business Media ISBN: 1441994343 Category : Medical Languages : en Pages : 397
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: Aage R. Møller Publisher: Karger Medical and Scientific Publishers ISBN: 3805581572 Category : Medical Languages : en Pages : 237
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: David Zhou Publisher: Springer Science & Business Media ISBN: 0387772618 Category : Technology & Engineering Languages : en Pages : 391
Book Description
Significant progress has been made in the development of neural prostheses to restore human functions and improve the quality of human life. Biomedical engineers and neuroscientists around the world are working to improve design and performance of existing devices and to develop novel devices for artificial vision, artificial limbs, and brain–machine interfaces. This book, Implantable Neural Prostheses 1: Devices and Applications,ispart one of a two-book series and describes state-of-the-art advances in techniques associated with implantable neural prosthetic devices and their applications. Devices covered include sensory prosthetic devices, such as visual implants, cochlear implants, auditory midbrain implants, and spinal cord stimulators. Motor prosthetic devices, such as deep brain stimulators, Bion microstimu- tors, the brain control and sensing interface, and cardiac electro-stimulation devices are also included. Progress in magnetic stimulation that may offer a non-invasive approach to prosthetic devices is introduced. Regulatory approval of implantable medical devices in the United States and Europe is also discussed.
Author: R. Saba Publisher: ISBN: Category : Languages : en Pages :
Book Description
Cochlear implants have been shown to successfully restore hearing to the profoundly deaf. Despite this achievement, issues remain concerning the power consumption and the accuracy of stimulation. This thesis is mainly concerned with investigating the spread of stimulation voltage within the cochlea. The power required to generate the stimulus is also investigated, as is the feasibility of powering a fully implanted cochlear implant by harvesting energy from head motion. Several different models have been used to study the voltage distribution within the cochlea due to electrical stimulation from individual electrodes of a cochlear implant. A resistive cable model is first used to illustrate the fall-off of the voltage with distance at the electrode positions along the cochlea. A three-dimensional finite element model of the cochlea is then developed to obtain the voltage distribution at positions closer to the site of neural stimulation. This model is used to demonstrate the way that the voltage distribution varies with the geometry of the cochlea and the electrode array. It was found that placing the return electrode of the implant within the modiolus, as opposed to outside the cochlea, resulted in higher stimulation for the same current input, which reduces the power requirements. The model has also been used to investigate the consequences of a current-steering, or stimulation focussing, strategy that has previously been proposed. A generalisation of this strategy is suggested, whereby impedance information at the neural level, along the path of the spiral ganglion, was used to optimise the focussed voltage distribution at the target neurons. The power consumption of various stimulation strategies is then estimated in order to assess their energy efficiency. Strategies are defined by parameters such as stimulation rate and number of active channels. The feasibility has also been investigated of harvesting electrical energy from head motion, to power a fully-implanted cochlear implant. It was demonstrated that more power could be harvested from higher harmonics but that this would be sensitive to walking speed. The practical approach is to have a heavily damped device that is insensitive.
Author: Tania Hanekom
Author: Joseph M. Miller
Author: Fan-Gang Zeng
Author: Tania Hanekom
Author: Fan-Gang Zeng
Author: Aage R. Møller
Author: David Zhou
Author: David Henchi Liang
Author: Robert G. Mathews
Author: Daniel Kipping
Author: R. Saba