Modeling the electrode–neuron interface of cochlear implants: Effects of neural survival, electrode placement, and the partial tripolar configuration

Goldwyn, Joshua H.; Bierer, Steven M.; Bierer, Julie Arenberg

doi:10.1016/j.heares.2010.05.005

Cited by 107 publications

(124 citation statements)

References 44 publications

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“…This was similar to the results of Berenstein et al (2010), who also found a significantly reduced EFI width as long as the σ of pTP stimulation was greater than 0.5. Although modeling studies (Bonham and Litvak 2008;Goldwyn et al 2010) suggest that larger σ for pTP stimulation may lead to more focused or narrower distributions of electrical potentials, there was insufficient power to perform the correlation test between the width of the EFI pattern and σ across the small number of subjects in this study. Steered pTP Stimuli.…”

Section: Efi Patternsmentioning

confidence: 93%

Excitation Patterns of Standard and Steered Partial Tripolar Stimuli in Cochlear Implants

Luo

2015

JARO

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Current steering in partial tripolar (pTP) mode has been shown to improve pitch perception and spectral resolution with cochlear implants (CIs). In this mode, a fraction (σ) of the main electrode current is returned within the cochlea and steered between the basal and apical flanking electrodes (with a proportion of α and 1 − α, respectively). Pitch generally decreases when α increases from 0 to 1, although the salience of pitch change varies across CI users. This study aimed to identify the mechanism of pitch changes with pTP-mode current steering and the factors contributing to the intersubject variability in pitch-ranking sensitivity. The electrical fields were measured for steered pTP stimuli on the same main electrode with α = 0, 0.5, and 1 in five implanted ears using electrical field imaging (EFI). The related excitation patterns were also measured physiologically using evoked compound action potential (ECAP) and psychophysically using psychophysical forward masking (PFM). Consistent with the pitch-ranking results in this study, the EFI, ECAP, and PFM centroids shifted apically with increasing α. An apical shift was also observed for the PFM peak but not for the EFI or ECAP peak. The pattern width was similar with different α values within a given measure (e.g., EFI, ECAP, or PFM), but the ECAP patterns were broader than the EFI and PFM patterns, possibly because ECAP was measured with smaller σ values than EFI and PFM. The amount of pattern shift with α depended on σ (i.e., the total amount of current used for steering) but was not correlated with the pitchranking sensitivity across subjects. The results revealed that the pitch changes elicited by pTP-mode current steering were not only driven by the shifts of excitation centroid.

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Section: Efi Patternsmentioning

confidence: 93%

Excitation Patterns of Standard and Steered Partial Tripolar Stimuli in Cochlear Implants

Luo

2015

JARO

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“…For example, compared to standard pTP mode, apically shifted pTP mode is expected to elicit lower pitch percepts with increasing α 1.3 mm for all electrodes. These parameters were adapted from Goldwyn et al (2010). Real CI users would have variable neural survival (Nadol et al 2001) and electrode-neuron distances (Finley and Skinner 2008), but that information was not available and thus was not modeled for the subjects in this study.…”

Section: Computational Modelmentioning

confidence: 99%

“…Table 1 summarizes the various stimulation configurations achievable with steered pTP mode using different combinations of α and σ. A computational model that simulates intra-cochlear potential fields and auditory neural response to CI stimulation (Goldwyn et al 2010) was used to investigate loudness and pitch perception with steered pTP mode. Similar models have been used to study loudness growth with standard pTP stimulation (Litvak et al 2007) and simulate current focusing and steering in various modes (Bonham and Litvak 2008).…”

Section: Introductionmentioning

confidence: 99%

“…Experiment 2 compared the pitches of loudness-balanced steered pTP stimuli on adjacent main electrodes to estimate the overlap between their pitch ranges. Figure 3 depicts the model of Goldwyn et al (2010), which simulates the spatial pattern of neural activity along the cochlea in response to CI stimulation. The model is briefly described here, and more details can be found in Goldwyn et al (2010).…”

Section: Introductionmentioning

confidence: 99%

“…Figure 3 depicts the model of Goldwyn et al (2010), which simulates the spatial pattern of neural activity along the cochlea in response to CI stimulation. The model is briefly described here, and more details can be found in Goldwyn et al (2010). In this model, the scala tympani is simplified as a 33-mm subsection of an infinitely long cylinder with a fixed radius of 1 mm.…”

Section: Introductionmentioning

confidence: 99%

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Current Steering with Partial Tripolar Stimulation Mode in Cochlear Implants

Luo

2012

JARO

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The large spread of excitation is a major cause of poor spectral resolution for cochlear implant (CI) users. Partial tripolar (pTP) mode has been proposed to reduce current spread by returning an equally distributed fraction (0.5×σ) of current to two flanking electrodes and the rest to an extra-cochlear ground. This study tested the efficacy of incorporating current steering into pTP mode to add spectral channels. Different proportions of current [α×σ and (1−α)×σ] were returned to the basal and apical flanking electrodes respectively to shape the electric field. Loudness and pitch perception with α from 0 to 1 in steps of 0.1 was simulated with a computational model of CI stimulation and tested on the apical, middle, and basal electrodes of six CI subjects. The highest σ allowing for full loudness growth within the implant compliance limit was chosen for each main electrode. Pitch ranking was measured between pairs of loudness-balanced steered pTP stimuli with an α interval of 0.1 at the most comfortable level. Results demonstrated that steered pTP stimuli with α around 0.5 required more current to achieve equal loudness than those with α around 0 or 1, maybe due to more focused excitation patterns. Subjects usually perceived decreasing pitches as α increased from 0 to 1, somewhat consistent with the apical shift of the center of gravity of excitation pattern in the model. Pitch discrimination was not better with α around 0.5 than with α around 0 or 1, except for some subjects and electrodes. For three subjects with better pitch discrimination, about half of the pitch ranges of two adjacent main electrodes overlapped with each other in steered pTP mode. These results suggest that current steering with focused pTP mode may improve spectral resolution and pitch perception with CIs.

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Ultracompliant Hydrogel‐Based Neural Interfaces Fabricated by Aqueous‐Phase Microtransfer Printing

Huang

Ong

Kwon

et al. 2018

Adv Funct Materials

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Hydrogel-based electronics are ideally suited for neural interfaces because they exhibit ultracompliant mechanical properties that match that of excitable tissue in the brain and peripheral nerve. Hydrogel-based multielectrode arrays (MEA) can conformably interface with tissues to minimize inflammation and improve the reliability to enhance signal transduction.However, MEA substrates composed of swollen hydrogels exhibit low toughness and low adhesion stability when laminated on the tissue surface and also present technical challenges for processes commonly employed in MEA fabrication. Here, we describe a new strategy to fabricate ultracompliant MEA based on aqueous-phase transfer printing. This technique employs redox active adhesive motifs in hygroscopic polymer precursors that simultaneously form hydrogels through sol-gel phase transitions and bond to underlying microelectronic structures. Specifically, in situ gelation of 4-arm-polyethylene glycol-grafted catechol [PEG-Dopa]4 hydrogels induced by oxidation using Fe 3+ produces conformal adhesive contact with the underlying MEA, robust adhesion to electronic structures, and rapid dissolution of watersoluble sacrificial release layers. MEA are then integrated on hydrogel-based substrates to produce free standing ultracompliant neural probes, which are then laminated to the surface of the dorsal root ganglia in feline subjects to record single-unit neural activity.

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Modeling the electrode–neuron interface of cochlear implants: Effects of neural survival, electrode placement, and the partial tripolar configuration

Cited by 107 publications

References 44 publications

Excitation Patterns of Standard and Steered Partial Tripolar Stimuli in Cochlear Implants

Excitation Patterns of Standard and Steered Partial Tripolar Stimuli in Cochlear Implants

Current Steering with Partial Tripolar Stimulation Mode in Cochlear Implants

Ultracompliant Hydrogel‐Based Neural Interfaces Fabricated by Aqueous‐Phase Microtransfer Printing

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