Design and fabrication of multichannel cochlear implants for animal research

Rebscher, Stephen J.; Hetherington, Alexander; Snyder, Russell L.; Leake, Patricia A.; Bonham, Ben H.

doi:10.1016/j.jneumeth.2007.05.013

Cited by 33 publications

(26 citation statements)

References 68 publications

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“…The head was rotated and the left bulla was opened and the round window visualized. The cochlea was deafened with an intrascalar injection of neomycin sulfate, and a stimulating electrode custom-designed for the guinea pig (Rebscher et al, 2007) was inserted into the scala tympani through the round window. A silver wire was placed in the skin near the left ear canal and served as the extracochlear return electrode.…”

Section: Current Steering and Current Focusing Measured In The Inferimentioning

confidence: 99%

Current focusing and steering: Modeling, physiology, and psychophysics

Bonham

Litvak²

2008

Hearing Research

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165

138

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Current steering and current focusing are stimulation techniques designed to increase the number of distinct perceptual channels available to cochlear implant (CI) users by adjusting currents applied simultaneously to multiple CI electrodes. Previous studies exploring current steering and current focusing stimulation strategies are reviewed, including results of research using computational models, animal neurophysiology, and human psychophysics. Preliminary results of additional neurophysiological and human psychophysical studies are presented that demonstrate the success of current steering strategies in stimulating auditory nerve regions lying between physical CI electrodes, as well as current focusing strategies that excite regions narrower than those stimulated using monopolar configurations. These results are interpreted in the context of perception and speech reception by CI users. Disparities between results of physiological and psychophysical studies are discussed. The differences in stimulation used for physiological and psychophysical studies are hypothesized to contribute to these disparities. Finally, application of current steering and focusing strategies to other types of auditory prostheses is also discussed.

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Section: Current Steering and Current Focusing Measured In The Inferimentioning

confidence: 99%

Current focusing and steering: Modeling, physiology, and psychophysics

Bonham

Litvak²

2008

Hearing Research

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165

138

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“…The space-filling array and the methods used to fabricate it have been described in detail elsewhere (Rebscher et al, 2007).…”

Section: Intracochlear Arraysmentioning

confidence: 99%

Cochlear implant electrode configuration effects on activation threshold and tonotopic selectivity

2008

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The multichannel design of contemporary cochlear implants (CIs) is predicated on the assumption that each channel activates a relatively restricted and independent sector of the deaf auditory nerve array, just as a sound within a restricted frequency band activates a restricted region of the normal cochlea The independence of CI channels, however, is limited; and the factors that determine their independence, the relative overlap of the activity patterns that they evoke, are poorly understood. In this study, we evaluate the spread of activity evoked by cochlear implant channels by monitoring activity at 16 sites along the tonotopic axis of the guinea pig inferior colliculus (IC). "Spatial tuning curves" (STCs) measured in this way serve as an estimate of activation spread within the cochlea and the ascending auditory pathways. We contrast natural stimulation using acoustic tones with two kinds of electrical stimulation either (1) a loose fitting banded array consisting of a cylindrical silicone elastomer carrier with a linear series of ring contacts; or (2) a space-filling array consisting of a tapered silicone elastomer carrier that is designed to fit snugly into the guinea pig scala tympani with a linear series of ball contacts positioned along it Spatial tuning curves evoked by individual acoustic tones, and by activation of each contact of each array as a monopole, bipole or tripole were recorded. Several channel configurations and a wide range of electrode separations were tested for each array, and their thresholds and selectivity were estimated. The results indicate that the tapered space-filling arrays evoked more restricted activity patterns at lower thresholds than did the banded arrays. Monopolar stimulation (one intracochlear contact activated with an extracochlear return) using either array evoked broad activation patterns that involved the entire recording array at current levels <6dBSL, but at relatively low thresholds. Bi- and tri-polar configurations of both array types evoked more restricted activity patterns, but their thresholds were higher than those of monopolar configurations. Bipolar and tripolar configurations with closely spaced contacts evoked activity patterns that were comparable to those evoked by pure tones. As the spacing of bipolar electrodes was increased (separations >1mm), the activity patterns became broader and evoked patterns with two distinct threshold minima, one associated with each contact.

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“…The first involves drug-eluting structures formulated with anti-inflammatory drugs [21,22,23,24,25] and neurotrophin-eluting hydrogels [26,27,28,29,30,31]. The second approach involves integration of microfluidic channels into neural prostheses for in situ delivery of bioactive molecules with high temporal and spatial resolution [32,33,34,35,36,37,38,39]. Finally the use of organic conductive polymer (OCP) coatings, a novel class of materials that significantly decrease the impedance of electrodes, and also can provide controlled delivery of bioactive molecules at the electrode-neural interface [40,41,42,43,44,45,46,47,48,49,50].…”

Section: Neuro-bionic Devicesmentioning

confidence: 99%

“…To promote preservation of the auditory nerve, a number of studies have focused on modification of cochlear implants with an integrated drug delivery channel for intracochlear pharmaceutical intervention [36,37,38,39]. The channel is linked to a micro-osmotic pump or an infusion pump to control the flow rate.…”

Section: Integrated Microfabricated Systemsmentioning

confidence: 99%

“…The channel is linked to a micro-osmotic pump or an infusion pump to control the flow rate. The feasibility of concurrently delivering drugs and stimulating the auditory nerve has been demonstrated in animal models [36,39]. An example of a cochlear drug delivery device, based on a Nucleus Contour electrode, is described here.…”

Section: Integrated Microfabricated Systemsmentioning

confidence: 99%

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Controlled delivery for neuro-bionic devices

Yue

Moulton

Cook

et al. 2013

Advanced Drug Delivery Reviews

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Implantable electrodes interface with the human body for a range of therapeutic as well as diagnostic applications. Here we provide an overview of controlled delivery strategies used in neuro-bionics. Controlled delivery of bioactive molecules has been used to minimise reactive cellular and tissue responses and/or promote nerve preservation and neurite outgrowth toward the implanted electrode. These effects are integral to establishing a chronically stable and effective electrode-neural communication. Drug-eluting bioactive coatings, organic conductive polymers, or integrated microfabricated drug delivery channels are strategies commonly used.

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Design and fabrication of multichannel cochlear implants for animal research

Cited by 33 publications

References 68 publications

Current focusing and steering: Modeling, physiology, and psychophysics

Current focusing and steering: Modeling, physiology, and psychophysics

Cochlear implant electrode configuration effects on activation threshold and tonotopic selectivity

Controlled delivery for neuro-bionic devices

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