Application of triphasic pulses with adjustable phase amplitude ratio (PAR) for cochlear ECAP recording: I. Amplitude growth functions

2012 ◽  
Vol 205 (1) ◽  
pp. 202-211 ◽  
Author(s):  
Andreas Bahmer ◽  
Uwe Baumann
Keyword(s):  
Amplitude Ratio ◽  
Growth Functions ◽  
Phase Amplitude ◽  
Amplitude Growth

scholarly journals Effect of Chronological Age on Pulse Rate Discrimination in Adult Cochlear-Implant Users

2021 ◽  
Vol 25 ◽  
pp. 233121652110073
Author(s):  
Kelly C. Johnson ◽  
Zilong Xie ◽  
Maureen J. Shader ◽  
Paul G. Mayo ◽  
Matthew J. Goupell
Keyword(s):  
Pulse Rate ◽  
Compound Action Potential ◽  
Action Potential Amplitude ◽  
Growth Functions ◽  
Evoked Compound Action Potential ◽  
Rate Discrimination ◽  
Amplitude Growth ◽  
Temporal Pulse ◽  
Compound Action Potential Amplitude ◽  
Compound Action

Cochlear-implant (CI) users rely heavily on temporal envelope cues to understand speech. Temporal processing abilities may decline with advancing age in adult CI users. This study investigated the effect of age on the ability to discriminate changes in pulse rate. Twenty CI users aged 23 to 80 years participated in a rate discrimination task. They attempted to discriminate a 35% rate increase from baseline rates of 100, 200, 300, 400, or 500 pulses per second. The stimuli were electrical pulse trains delivered to a single electrode via direct stimulation to an apical (Electrode 20), a middle (Electrode 12), or a basal location (Electrode 4). Electrically evoked compound action potential amplitude growth functions were recorded at each of those electrodes as an estimate of peripheral neural survival. Results showed that temporal pulse rate discrimination performance declined with advancing age at higher stimulation rates (e.g., 500 pulses per second) when compared with lower rates. The age-related changes in temporal pulse rate discrimination at higher stimulation rates persisted after statistical analysis to account for the estimated peripheral contributions from electrically evoked compound action potential amplitude growth functions. These results indicate the potential contributions of central factors to the limitations in temporal pulse rate discrimination ability associated with aging in CI users.

scholarly journals The Precision of eCAP Thresholds Derived From Amplitude Growth Functions

2018 ◽  
Vol 39 (4) ◽  
pp. 701-711 ◽  
Author(s):  
Jan Dirk Biesheuvel ◽  
Jeroen J. Briaire ◽  
Johan H. M. Frijns
Keyword(s):  
Growth Functions ◽  
Amplitude Growth

scholarly journals Effects of Electrical Pulse Polarity Shape on Intra Cochlear Neural Responses in Humans: Triphasic Pulses with Anodic and Cathodic Second Phase

2020 ◽  
Author(s):  
Katharina Kretzer ◽  
David P. Herrmann ◽  
Sabrina H. Pieper ◽  
Andreas Bahmer
Keyword(s):  
Pulse Shape ◽  
Amplitude Ratio ◽  
Electrical Pulse ◽  
Second Phase ◽  
Neural Responses ◽  
Compound Action Potentials ◽  
Psychophysical Threshold ◽  
Pulse Polarity ◽  
Phase Amplitude ◽  
Pulse Stimulation

Modern cochlear implants employ charge-balanced biphasic and triphasic pulses. However, the effectiveness of electrical pulse shape and polarity is still a matter of debate. For this purpose, in a previous study (Bahmer & Baumann, 2013) electrophysiological and psychophysical measurement after triphasic pulse stimulation with cathodic second phase was determined. Depending on the pulse shape configuration, the stimulation effectiveness differed similarly for electrophysiological and psychophysical measurements. However, the experiments were limited to stimulation pulses with cathodic second phase. In this study, cathodic and anodic second phase stimulation was applied. Evoked compound action potentials (ECAPs) and psychophysical responses were recorded in eleven cochlear implant recipients (SYNCHRONY/SONATAti100/PULSARci100 devices, MED-EL Innsbruck). We compared the strength of the ECAP responses with individual psychophysical threshold levels depending on the pulse shape. Results for pulses with cathodic second phase showed the weakest ECAP response and highest psychophysical thresholds for symmetric triphasic pulse shapes, and the strongest ECAP response and lowest psychophysical thresholds for biphasic pulses. The ECAP responses for anodic second phase differed from the results of triphasic stimulation with cathodic second phase. The U-shape of the ECAP response with increasing phase amplitude ratio (PAR) for cathodic second phase could not be observed for the anodic second phase. Instead, a flat curve was observed. In contrast, psychophysical threshold curves with increasing PAR were similar between cathodic and anodic second phase stimulation.

Changes in electric organ discharge after pausing the electromotor system of Gymnotus carapo

2000 ◽  
Vol 203 (9) ◽  
pp. 1433-1446 ◽  
Author(s):  
S. Schuster
Keyword(s):  
Electric Organ Discharge ◽  
Amplitude Ratio ◽  
Electric Organ ◽  
Recovery Phase ◽  
Weakly Electric Fish ◽  
Electromotor System ◽  
Phase Amplitude ◽  
Electric Organ Discharges ◽  
Induced Changes ◽  
Weakly Electric

During their entire lives, weakly electric fish produce an uninterrupted train of discharges to electrolocate objects and to communicate. In an attempt to learn about activity-dependent processes that might be involved in this ability, the continuous train of discharges of intact Gymnotus carapo was experimentally interrupted to investigate how this pausing affects post-pause electric organ discharges. In particular, an analysis was conducted of how the amplitude and relative timing of the three major deflections of the complex discharge change over the course of the first 1000 post-pause discharges. The dependence of these variables on the duration of the preceding pause and on water temperature is analysed. In addition, pause-induced small reverberations at the end of the discharge are described. Common to all amplitude changes is a fast initial decrease in amplitude with a slow recovery phase; amplitude changes scale with the duration of the preceding pause and are independent of the interdischarge interval. The absence of changes in the postsynaptic-potential-derived first phase of the discharge together with changes in the amplitude ratio of the third and fourth deflections suggest that the amplitude changes are mainly due to pause-induced changes in the inner resistance of the electric organ. A model is formulated that approximates the pattern of amplitude changes. The post-pause changes described here may provide a new way to test current models of complex discharge generation in Gymnotus carapo and illustrate the speed at which changes of an electric organ discharge can take place.

scholarly journals Amplitude Growth Functions of Auditory Nerve Responses to Electric Pulse Stimulation With Varied Interphase Gaps in Cochlear Implant Users With Ipsilateral Residual Hearing

2021 ◽  
Vol 25 ◽  
pp. 233121652110141
Author(s):  
Marina Imsiecke ◽  
Andreas Büchner ◽  
Thomas Lenarz ◽  
Waldo Nogueira
Keyword(s):  
Cochlear Implant ◽  
Dynamic Range ◽  
Electric Pulse ◽  
Objective Measure ◽  
Stimulus Level ◽  
Control Group ◽  
Electrode Impedance ◽  
Residual Hearing ◽  
Growth Functions ◽  
Amplitude Growth

Amplitude growth functions (AGFs) of electrically evoked compound action potentials (eCAPs) with varying interphase gaps (IPGs) were measured in cochlear implant users with ipsilateral residual hearing (electric-acoustic stimulation [EAS]). It was hypothesized that IPG effects on AGFs provide an objective measure to estimate neural health. This hypothesis was tested in EAS users, as residual low-frequency hearing might imply survival of hair cells and hence better neural health in apical compared to basal cochlear regions. A total of 16 MED-EL EAS subjects participated, as well as a control group of 16 deaf cochlear implant users. The IPG effect on the AGF characteristics of slope, threshold, dynamic range, and stimulus level at 50% maximum eCAP amplitude (level50%) was investigated. AGF threshold and level50% were significantly affected by the IPG in both EAS and control group. The magnitude of AGF characteristics correlated with electrode impedance and electrode-modiolus distance (EMD) in both groups. In contrast, the change of the AGF characteristics with increasing IPG was independent of these electrode-specific measures. The IPG effect on the AGF level50% in both groups, as well as on the threshold in EAS users, correlated with the duration of hearing loss, which is a predictor of neural health. In EAS users, a significantly different IPG effect on level50% was found between apical and medial electrodes. This outcome is consistent with our hypothesis that the influence of IPG effects on AGF characteristics provides a sensitive measurement and may indicate better neural health in the apex compared to the medial cochlear region in EAS users.

scholarly journals Simultaneous activation of multiple vestibular pathways upon electrical stimulation of semicircular canal afferents

2020 ◽  
Vol 267 (S1) ◽  
pp. 273-284
Author(s):  
Anissa Boutabla ◽  
Samuel Cavuscens ◽  
Maurizio Ranieri ◽  
Céline Crétallaz ◽  
Herman Kingma ◽  
...  
Keyword(s):  
Phase 1 ◽  
Bilateral Vestibulopathy ◽  
Growth Functions ◽  
Simultaneous Activation ◽  
Promising Treatment ◽  
Stimulation Current ◽  
Electrical Stimuli ◽  
Amplitude Growth ◽  
Vestibular Pathways ◽  
Stimulation Of

Abstract Background and purpose Vestibular implants seem to be a promising treatment for patients suffering from severe bilateral vestibulopathy. To optimize outcomes, we need to investigate how, and to which extent, the different vestibular pathways are activated. Here we characterized the simultaneous responses to electrical stimuli of three different vestibular pathways. Methods Three vestibular implant recipients were included. First, activation thresholds and amplitude growth functions of electrically evoked vestibulo-ocular reflexes (eVOR), cervical myogenic potentials (ecVEMPs) and vestibular percepts (vestibulo-thalamo-cortical, VTC) were recorded upon stimulation with single, biphasic current pulses (200 µs/phase) delivered through five different vestibular electrodes. Latencies of eVOR and ecVEMPs were also characterized. Then we compared the amplitude growth functions of the three pathways using different stimulation profiles (1-pulse, 200 µs/phase; 1-pulse, 50 µs/phase; 4-pulses, 50 µs/phase, 1600 pulses-per-second) in one patient (two electrodes). Results The median latencies of the eVOR and ecVEMPs were 8 ms (8–9 ms) and 10.2 ms (9.6–11.8 ms), respectively. While the amplitude of eVOR and ecVEMP responses increased with increasing stimulation current, the VTC pathway showed a different, step-like behavior. In this study, the 200 µs/phase paradigm appeared to give the best balance to enhance responses at lower stimulation currents. Conclusions This study is a first attempt to evaluate the simultaneous activation of different vestibular pathways. However, this issue deserves further and more detailed investigation to determine the actual possibility of selective stimulation of a given pathway, as well as the functional impact of the contribution of each pathway to the overall rehabilitation process.

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