Current focusing and steering: Modeling, physiology, and psychophysics

Bonham, Ben H.; Litvak, Leonid M.

doi:10.1016/j.heares.2008.03.006

Cited by 163 publications

(146 citation statements)

References 83 publications

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“…Electrode placement and design could be adapted to specifically target remaining intact neurons in the ampullae, along the course of the vestibular nerve branches or Scarpa's ganglion to better address the patient's specific vestibular pathology (Van De Berg et al 2012, Guinand et al 2015). Furthermore, a multisite electrode array with a forked design (Valentin et al 2013) or a double-sided design (Poppendieck et al 2014) would facilitate fine-tuning of stimulation through multipolar stimulation, similar to investigations in cochlear implants (Bonham and Litvak 2008). These refinements will have to be evaluated as they could change the recruitment of primary afferents and improve the responses to PRM and, or PAM.…”

Section: Effects Of Pulse Modulation On Peak Eye Velocitymentioning

confidence: 99%

Characterization of pulse amplitude and pulse rate modulation for a human vestibular implant during acute electrical stimulation

et al. 2016

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Objective. The vestibular system provides essential information about balance and spatial orientation via the brain to other sensory and motor systems. Bilateral vestibular loss significantly reduces quality of life, but vestibular implants (VIs) have demonstrated potential to restore lost function. However, optimal electrical stimulation strategies have not yet been identified in patients. In this study, we compared the two most common strategies, pulse amplitude modulation (PAM) and pulse rate modulation (PRM), in patients. Approach. Four subjects with a modified cochlear implant including electrodes targeting the peripheral vestibular nerve branches were tested. Chargeequivalent PAM and PRM were applied after adaptation to baseline stimulation. Vestibulo-ocular reflex eye movement responses were recorded to evaluate stimulation efficacy during acute clinical testing sessions. Main results. PAM evoked larger amplitude eye movement responses than PRM. Eye movement response axes for lateral canal stimulation were marginally better aligned with PRM than with PAM. A neural network model was developed for the tested stimulation strategies to provide insights on possible neural mechanisms. This model suggested that PAM would consistently cause a larger ensemble firing rate of neurons and thus larger responses than PRM. Significance. Due to the larger magnitude of eye movement responses, our findings strongly suggest PAM as the preferred strategy for initial VI modulation.

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Section: Effects Of Pulse Modulation On Peak Eye Velocitymentioning

confidence: 99%

Characterization of pulse amplitude and pulse rate modulation for a human vestibular implant during acute electrical stimulation

et al. 2016

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“…Alternatively, the shape of an fmSTC might be broader with an MP masker because the spread of current along the cochlear duct is more gradual with an MP stimulus than with a BP stimulus (Black et al, 1983). A recent comprehensive review of electrode configuration effects (Bonham and Litvak, 2008) suggests that additional research is required to understand how electrode configuration may influence spatial selectivity in individual cochlear implant users.…”

Section: Effects Of Electrode Regionmentioning

confidence: 99%

Spatial tuning curves from apical, middle, and basal electrodes in cochlear implant users

Nelson¹,

Kreft²,

Anderson³

et al. 2011

The Journal of the Acoustical Society of America

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Forward-masked psychophysical spatial tuning curves (fmSTCs) were measured in 15 cochlearimplant subjects, 10 using monopolar stimulation and 5 using bipolar stimulation. In each subject, fmSTCs were measured at several probe levels on an apical, middle, and basal electrode using a fixed-level probe stimulus and variable-level maskers. Tuning curve slopes and bandwidths did not change significantly with probe level for electrodes located in the apical, middle, or basal region although a few subjects exhibited dramatic changes in tuning at the extremes of the probe level range. Average tuning curve slopes and bandwidths did not vary significantly across electrode regions. Spatial tuning curves were symmetrical and similar in width across the three electrode regions. However, several subjects demonstrated large changes in slope and=or bandwidth across the three electrode regions, indicating poorer tuning in localized regions of the array. Cochlearimplant users exhibited bandwidths that were approximately five times wider than normal-hearing acoustic listeners but were in the same range as acoustic listeners with moderate cochlear hearing loss. No significant correlations were found between spatial tuning parameters and speech recognition; although a weak relation was seen between middle electrode tuning and transmitted information for vowel second formant frequency.

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“…Simultaneous VC stimulation has been shown to produce a similar amount of current spread as with stimulation of a single electrode (Busby et al, 2008;Bonham and Litvak, 2008). For a fixed amount of current, stimulation of a single electrode and a simultaneous VC have approximately the same loudness (Donaldson et al, 2005;Luo et al, 2010;Frijns et al, 2009).…”

Section: Introductionmentioning

confidence: 95%

Discrimination between sequential and simultaneous virtual channels with electrical hearing

Landsberger

Galvin

2011

The Journal of the Acoustical Society of America

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In cochlear implants (CIs), simultaneous or sequential stimulation of adjacent electrodes can produce intermediate pitch percepts between those of the component electrodes. However, it is unclear whether simultaneous and sequential virtual channels (VCs) can be discriminated. In this study, CI users were asked to discriminate simultaneous and sequential VCs; discrimination was measured for monopolar (MP) and bipolar þ 1 stimulation (BP þ 1), i.e., relatively broad and focused stimulation modes. For sequential VCs, the interpulse interval (IPI) varied between 0.0 and 1.8 ms. All stimuli were presented at comfortably loud, loudness-balanced levels at a 250 pulse per second per electrode (ppse) stimulation rate. On average, CI subjects were able to reliably discriminate between sequential and simultaneous VCs. While there was no significant effect of IPI or stimulation mode on VC discrimination, some subjects exhibited better VC discrimination with BP þ 1 stimulation. Subjects' discrimination between sequential and simultaneous VCs was correlated with electrode discrimination, suggesting that spatial selectivity may influence perception of sequential VCs. To maintain equal loudness, sequential VC amplitudes were nearly double those of simultaneous VCs, presumably resulting in a broader spread of excitation. These results suggest that perceptual differences between simultaneous and sequential VCs might be explained by differences in the spread of excitation.

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Current focusing and steering: Modeling, physiology, and psychophysics

Cited by 163 publications

References 83 publications

Characterization of pulse amplitude and pulse rate modulation for a human vestibular implant during acute electrical stimulation

Characterization of pulse amplitude and pulse rate modulation for a human vestibular implant during acute electrical stimulation

Spatial tuning curves from apical, middle, and basal electrodes in cochlear implant users

Discrimination between sequential and simultaneous virtual channels with electrical hearing

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