Pitch ranking, electrode discrimination, and physiological spread of excitation using current steering in cochlear implants

AbstractContemporary cochlear implants (CIs) use cathodic-leading, symmetrical, biphasic current pulses, despite a growing body of evidence that suggests anodic-leading pulses may be more effective at stimulating the auditory system. However, since much of this research on humans has used pseudomonophasic pulses or biphasic pulses with unusually long interphase gaps, the effects of stimulus polarity are unclear for clinically relevant (i.e., symmetric biphasic) stimuli.The purpose of this study was to examine the effects of stimulus polarity on basic characteristics of physiological spread-of-excitation (SOE) measures obtained with the electrically evoked compound action potential (ECAP) in CI recipients using clinically relevant stimuli.Using a within-subjects (repeated measures) design, we examined the differences in mean amplitude, peak electrode location, area under the curve, and spatial separation between SOE curves obtained with anodic- and cathodic-leading symmetrical, biphasic pulses.Fifteen CI recipients (ages 13–77) participated in this study. All were users of Cochlear Ltd. devices.SOE functions were obtained using the standard forward-masking artifact reduction method. Probe electrodes were 5–18, and they were stimulated at an 8 (of 10) loudness rating (“loud”). Outcome measures (mean amplitude, peak electrode location, curve area, and spatial separation) for each polarity were compared within subjects.Anodic-leading current pulses produced ECAPs with larger average amplitudes, greater curve area, and less spatial separation between SOE patterns compared with that for cathodic-leading pulses. There was no effect of polarity on peak electrode location.These results indicate that for equal current levels, the anodic-leading polarity produces broader excitation patterns compared with cathodic-leading pulses, which reduces the spatial separation between functions. This result is likely due to preferential stimulation of the central axon. Further research is needed to determine whether SOE patterns obtained with anodic-leading pulses better predict pitch discrimination.

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Effect of Stimulus and Recording Parameters on Spatial Spread of Excitation and Masking Patterns Obtained With the Electrically Evoked Compound Action Potential in Cochlear Implants

Ear and Hearing ◽

10.1097/aud.0b013e3181e1d19e ◽

2010 ◽

Vol 31 (5) ◽

pp. 679-692 ◽

Cited By ~ 15

Author(s):

Michelle L. Hughes ◽

Lisa J. Stille

Keyword(s):

Action Potential ◽

Cochlear Implants ◽

Compound Action Potential ◽

Spatial Spread ◽

Evoked Compound Action Potential ◽

Spread Of Excitation ◽

Compound Action

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Music Perception in Adult Users of Cochlear Implants: A Brief Review

Perspectives on Aural Rehabilitation and Its Instrumentation ◽

10.1044/arii22.1.4 ◽

2015 ◽

Vol 22 (1) ◽

pp. 4-11

Author(s):

Robert C. Jensen ◽

Sarah Hargus Ferguson

Keyword(s):

Cochlear Implants ◽

Music Perception ◽

Training Programs ◽

Musical Training ◽

Current Steering ◽

Structure Information ◽

Auditory Nervous System ◽

Processing Strategies ◽

Melody Perception ◽

Place Pitch

Although cochlear implants (CIs) can provide good speech understanding in quiet, in general, users of CIs have shown poor music perception performance, particularly with regard to pitch (and hence melody). This is primarily due to the limited ability of CI processing strategies and electric stimulation to provide place pitch and fine structure information from the original input signal to the auditory nervous system of the user. Approaches such as current focusing, current steering, enhanced amplitude modulation cues, and optic stimulation have been shown or theorized to assist in music perception, as have musical training programs. This article is a brief review of research related to music perception in adults with CIs, specifically their rhythm, pitch, and melody perception performance; processing strategies that have been or are being developed which might improve their music perception performance; and music training programs that have been shown to improve their music perception performance.

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Current Steering with Partial Tripolar Stimulation Mode in Cochlear Implants

Journal of the Association for Research in Otolaryngology ◽

10.1007/s10162-012-0366-8 ◽

2012 ◽

Vol 14 (2) ◽

pp. 213-231 ◽

Cited By ~ 13

Author(s):

Ching-Chih Wu ◽

Xin Luo

Keyword(s):

Cochlear Implants ◽

Current Steering ◽

Stimulation Mode

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Psychophysical measures of tonotopic selectivity in cats and humans

10.31234/osf.io/x5u2v ◽

2021 ◽

Author(s):

Robert P. Carlyon ◽

John C. Middlebrooks ◽

Matthew L. Richardson ◽

Robin Gransier ◽

François Guérit ◽

...

Keyword(s):

Cochlear Implants ◽

Pure Tone ◽

Electrophysiological Study ◽

Center Frequency ◽

Auditory Prosthesis ◽

Auditory Filter ◽

Non Invasive ◽

Spread Of Excitation ◽

Novel Approaches ◽

Electrophysiological Methods

Sound spectra are represented by patterns of activity along the tonotopic axis ofthe cochlea. Cochlear implants can transmit spectra by stimulating tonotopicallyappropriate electrodes, but fidelity is limited by intracochlear spread of excitation. We aim to better evaluate present-day experimental stimulation procedures and, potentially, to improve transmission of spectra with novel stimulation modalities. As a first step, we are developing non-invasive measures of tonotopic spread of excitation that can be compared between normal-hearing cats and humans. These measures include psychophysics in the present study and scalp-recorded electrophysiology in a companion study (Guérit et al., 2021). Cats and humans detected pure-tone probes presented in continuous 1/8- and 1-oct noise-band maskers. Masker bandwidths were readily discernable in both species by the dependence of masked thresholds on probe frequencies. Thresholds were largely constant across the bandwidth of the 1-oct masker, whereas thresholds dropped markedly at frequencies away from the center of the 1/8-oct masker. Cats and humans differed in that the feline auditory filter centered on 8 kHz, which we measured using a notched-noise procedure, was 22% wider than published values for humans at the same center frequency. Also, thresholds for the cats in the 1-octmasker condition consistently were 1.0 to 3.2 dB higher than expected based on the estimated masker power in the feline auditory filter. The present psychophysical results parallel those in our companion electrophysiological study, thereby providing perceptual validation for that study. These psychophysical and electrophysiological methods will be valuable for future investigations of novel approaches for auditory prosthesis.

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