Simultaneous and non-simultaneous dual electrode stimulation in cochlear implants: evidence for two neural response modalities

Frijns, Johan H. M.; Kalkman, Randy K.; Vanpoucke, Filiep; Bongers, Jorien Snel; Briaire, Jeroen J.

doi:10.1080/00016480802610218

Cited by 52 publications

(65 citation statements)

References 14 publications

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“…The strong difference of level between equally loud sequential and simultaneous stimuli in MP mode was expected and has been previously reported. Frijns et al (2009) found a difference of 6 dB between the intensity of equally loud simultaneous and sequential dual-electrode MP stimuli separated by only one electrode (equivalent to 1.1 mm with the Advanced Bionics®HiFocus1J™ electrode array). Landsberger and Galvin (2011) found a slightly smaller difference of about 5.1 dB between similar stimuli also using Advanced Bionics devices.…”

Section: Discussionmentioning

confidence: 96%

Perceptual Interactions Between Electrodes Using Focused and Monopolar Cochlear Stimulation

Marozeau

McDermott

Swanson

et al. 2015

JARO

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In today's cochlear implant (CI) systems, the monopolar (MP) electrode configuration is the most commonly used stimulation mode, requiring only a single current source. However, with an implant that will allow simultaneous activation of multiple independent current sources, it is possible to implement an all-polar (AP) stimulation mode designed to create a focused electrical field. The goal of this experiment was to study the potential benefits of this all-polar mode for reducing uncontrolled electrode interactions compared with the monopolar mode. The five participants who took part in the study were implanted with a research device that was connected via a percutaneous connector to a benchtop stimulator providing 22 independent current sources. The perceptual effects of the AP mode were tested in three experiments. In Experiment 1, the current level difference between loudness-matched sequential and simultaneous stimuli composed of 2 spatially separated pulse trains was measured as function of the electrode separation. Results indicated a strong current-summation interaction for simultaneous stimuli in the MP mode for separations up to at least 4.8 mm. No significant interaction was found in the AP mode beyond a separation of 2.4 mm. In Experiment 2, a forward-masking paradigm was used with fixed equally loud probes in AP and MP modes, and AP maskers presented on different electrode positions. Results indicated a similar spatial masking pattern between modes. In Experiment 3, subjects were asked to discriminate between across-electrode temporal delays. It was hypothesized that discrimination would decrease with electrode separation faster in AP compared to MP modes. However, results showed no difference between the two modes. Overall, the results indicated that the AP mode produced less current spread than MP mode but did not lead to a significant advantage in terms of spread of neuronal excitation at equally loud levels.

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Section: Discussionmentioning

confidence: 96%

Perceptual Interactions Between Electrodes Using Focused and Monopolar Cochlear Stimulation

Marozeau

McDermott

Swanson

et al. 2015

JARO

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“…This discrepancy might well be caused by an underestimation of the spread of excitation (SOE) in the model. The narrower the SOE, the higher the need for current correction (Frijns et al 2009b). The SOE in the model is not only influenced by the TL criterion (Figure 3) but also by the (absence of) stochastic neural behaviour and the spatial distribution of the cell bodies in the SG.…”

Section: Discussionmentioning

confidence: 99%

“…Based on previous computational and physiological results (Bonham and Litvak 2008;Frijns et al 2009b) it was hypothesized that current steering at TL requires a current correction in order to maintain equal loudness for all current weighting combinations between a pair of electrodes. However, TLs are not significantly influenced by the current steering coefficient, at least for adjacent and nonadjacent electrode pairs up to 2.2 mm wide.…”

Section: Discussionmentioning

confidence: 99%

“…In addition, TL is part of the clinical fitting procedure. At MCL, a current correction is needed to maintain constant loudness for non-simultaneous DES on adjacent electrodes, while it is not for most simultaneous DES (Donaldson et al 2005;Frijns et al 2009b;Snel-Bongers et al 2011;Snel-Bongers et al 2012). Based on the findings with our computational model described above ( Figure 1A, B), it was hypothesized that such a current correction is also needed when current steering is employed close to TL.…”

Section: Introductionmentioning

confidence: 91%

“…Frijns et al (2009b) examined the neural excitation pattern for both simultaneous and sequential DES, both psychophysically and using computational modeling. For current levels close to Most Comfortable Loudness level (MCL), they found that the excitation area moves smoothly between the contacts as a function of α producing an almost constant loudness ( Figure 1C, D).…”

Section: Introductionmentioning

confidence: 99%

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Threshold Levels of Dual Electrode Stimulation in Cochlear Implants

Snel-Bongers

Briaire

Veen

et al. 2013

JARO

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Simultaneous stimulation on two contacts (current steering) creates intermediate pitches between the physical contacts in cochlear implants. All recent studies on current steering have focused on Most Comfortable Loudness levels and not at low stimulation levels. This study investigates the efficacy of dual electrode stimulation at lower levels, thereby focusing on the requirements to correct for threshold variations. With a current steered signal, threshold levels were determined on 4 different electrode pairs for 7 different current steering coefficients (α). This was done psychophysically in twelve postlingually deafened cochlear implant (HiRes90K, HiFocus1J) users and, in a computer model, which made use of three different neural morphologies. The analysis on the psychophysical data taking all subjects into account showed that in all conditions there was no significant difference between the threshold level of the physical contacts and the intermediate created percepts, eliminating the need for current corrections at these very low levels. The model data showed unexpected drops in threshold in the middle of the two physical contacts (both contacts equal current). Results consistent with this prediction were obtained for a subset of 5 subjects for the apical pair with wider spacing (2.2 mm). Further analysis showed that this decrease was only observed in subjects with a long duration of deafness. For current steering on adjacent contacts, the results from the psychophysical experiments were in line with the results from computational modelling. However, the dip in the threshold profile could only be replicated in the computational model with surviving peripheral processes without an unmyelinated terminal. On the basis of this result, we put forward that the majority of the surviving spiral ganglion cells in the cochlea in humans with a long duration of deafness still retain peripheral processes, but have lost their unmyelinated terminals.

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Auditory Prosthesis

Frijns

Briaire

2022

Encyclopedia of Computational Neuroscience

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Simultaneous and non-simultaneous dual electrode stimulation in cochlear implants: evidence for two neural response modalities

Cited by 52 publications

References 14 publications

Perceptual Interactions Between Electrodes Using Focused and Monopolar Cochlear Stimulation

Perceptual Interactions Between Electrodes Using Focused and Monopolar Cochlear Stimulation

Threshold Levels of Dual Electrode Stimulation in Cochlear Implants

Auditory Prosthesis

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