Andreas Bahmer - Academia.edu (original) (raw)

Papers by Andreas Bahmer

Research paper thumbnail of Effects of electrical pulse polarity shape on intra cochlear neural responses in humans: Triphasic pulses with cathodic second phase

Hearing Research, Dec 1, 2013

Charge balanced pulses are used in modern cochlear implants to avoid direct current (DC) stimulat... more Charge balanced pulses are used in modern cochlear implants to avoid direct current (DC) stimulation that may damage neural tissues. In this context the effect of electrical pulse shape and polarity is still a matter of debate and the most effective pulse shape needs to be determined (Bahmer et al., 2010a; Undurraga et al., 2010; Wieringen et al., 2008; Macherey et al., 2008). Therefore, we conducted electrophysiological measurements, namely electrical compound action potentials (ECAPs) to assess response strength elicited by various pulse shapes and polarities in five cochlear implant recipients (SonataTI100/PulsarCI100 devices, MED-EL Innsbruck). ECAP response strength depending on pulse shape was compared with individual psychophysical thresholds. Results indicated the weakest response amplitude and highest thresholds for symmetric triphasic pulse shapes (with cathodic second phase), and the strongest response amplitude and lowest thresholds for biphasic pulses with anodic first phase. Biphasic pulses with cathodic first phase generated intermediate response amplitude and thresholds.

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Research paper thumbnail of Triphasic Pulses Reduce Facial Nerve Stimulation in CI Users: Intra- and Postoperative Electromyographic Data

Forschung heute – Zukunft morgen, 2018

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Research paper thumbnail of Using the Floating Mass Transducer (FMT) as a microphone – a possibility to develop a fully implantable CI?

Laryngo-rhino-otologie, Apr 1, 2018

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Research paper thumbnail of Computer simulation of chopper neurons

The aim of this work was to test a new model for oscillating neurons (chopper neurons) in the coc... more The aim of this work was to test a new model for oscillating neurons (chopper neurons) in the cochlear nucleus of the auditory system. In the beginning, it is shown that multiples of 0.4 ms are apparent in intrinsic oscillations in the auditory system and in pitch shift experiments. The existence of a time constant of 0.4 ms is explained by the assumption of a minimum chemical synaptic delay of this size between chopper neurons. The large dynamic range of periodicity coding, the small dynamic range of pure tone response, and the sharp frequency tuning of chopper neurons can be explained as a functional result of simultaneous projections from both the auditory nerve fibers and onset neurons to chopper neurons. As a consequence, the topology of the simulation of chopper neurons is as follows: To ensure the preference for multiples of 0.4 ms as observed in physiological and psychophysical experiments, chopper neurons are arranged in a circular network. The minimum number of two chopper...

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Research paper thumbnail of Physiologically inspired coding strategies for cochlear implants

IFMBE Proceedings, 2009

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Research paper thumbnail of The Underlying Mechanism of Preventing Facial Nerve Stimulation by Triphasic Pulse Stimulation in Cochlear Implant Users Assessed With Objective Measure

Otology & Neurotology, 2016

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Research paper thumbnail of Application of triphasic pulses with adjustable phase amplitude ratio (PAR) for cochlear ECAP recording: II. Recovery functions

Journal of Neuroscience Methods, 2012

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Research paper thumbnail of Pitch Matching Psychometrics in Electric Acoustic Stimulation

Ear & Hearing, 2011

Combined electric-acoustic stimulation (EAS) is a therapeutic option for patients with severe to ... more Combined electric-acoustic stimulation (EAS) is a therapeutic option for patients with severe to profound mid- and high-frequency hearing loss while low-frequency hearing is mostly unaffected. The present study investigates bimodal pitch matching in EAS users as a function of the angular placement of electrodes. Results are compared with data obtained from previous pitch matching studies. Knowledge of electric and acoustic pitch mapping may be important for effective fitting to control the frequency range of acoustic and electric processing. Pitch adjustment experiments were conducted in eight subjects with residual hearing in the opposite ear as well as in the implanted ear. Four subjects received a standard 31.5-mm electrode array and four subjects received the shorter, more flexible 24-mm FLEX electrode array (PULSARCI100 or SONATATI100 stimulator, MED-EL, Innsbruck, Austria). The subjects' task was to listen to single-electrode stimuli presented at a fixed rate (800 pulses per second) via the cochlear implant and to adjust the frequency of the acoustic stimulus until the perceived pitch matched the perception of the electrically conveyed stimulus. Two to four of the most apical electrodes were tested depending on the range of the individual's residual hearing. Postoperative x rays (modified Stenver's view) were analyzed to compare individual pitch matching data in terms of the electrode arrays' insertion angle. The average mean frequency match for the most apical electrode 1 in EAS subjects implanted with the FLEX array was 583 Hz, while for the two subjects with a deep insertion of the 31.5-mm standard electrode array, the matches were 128 and 223 Hz. Because the residual hearing in the EAS subgroup was rather limited in the high-frequency range, a limited number of basal electrodes were assessed to determine the slope of the electric place/pitch function. A considerable variation in terms of the individual pitch function was observed. The slope of the pitch function varied to a large extent among subjects. The differences between contra- and ipsilateral adjustments were very small (mean average 14 Hz) and within the range of the variance (average SD 124 Hz). The application of a pitch matching procedure to assess the electric/acoustic crossover frequency is feasible. In the present study, ipsi- and contralateral pitch matches made by EAS patients were nearly equal; therefore, a severe alteration in the excitation pattern of the basilar membrane in the implanted ear can be ruled out.

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Research paper thumbnail of Triphasische Pulse reduzieren Fazialisnervstimulation in CI-Nutzern: Intra- und postoperative elektromyographische Daten

Forschung heute – Zukunft morgen, 2018

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Research paper thumbnail of New parallel stimulation strategies revisited: Effect of synchronous multi electrode stimulation on rate discrimination in cochlear implant users

Cochlear Implants International, 2013

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Research paper thumbnail of Role of affordance in perception Decoding Sensory Input

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Research paper thumbnail of Rate pitch discrimination with double pulse intervals optimized using ECAP responses

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Research paper thumbnail of Elektrisch-akustischer Tonhöhenvergleich

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

Hearing Research

Charge balanced pulses are used in modern cochlear implants to avoid direct current (DC) stimulat... more Charge balanced pulses are used in modern cochlear implants to avoid direct current (DC) stimulation that may damage neural tissues. In this context the effect of electrical pulse shape and polarity is still a matter of debate and the most effective pulse shape needs to be determined (Bahmer et al., 2010a; Undurraga et al., 2010; Wieringen et al., 2008; Macherey et al., 2008). Therefore, we conducted electrophysiological measurements, namely electrical compound action potentials (ECAPs) to assess response strength elicited by various pulse shapes and polarities in five cochlear implant recipients (SonataTI100/PulsarCI100 devices, MED-EL Innsbruck). ECAP response strength depending on pulse shape was compared with individual psychophysical thresholds. Results indicated the weakest response amplitude and highest thresholds for symmetric triphasic pulse shapes (with cathodic second phase), and the strongest response amplitude and lowest thresholds for biphasic pulses with anodic first phase. Biphasic pulses with cathodic first phase generated intermediate response amplitude and thresholds.

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Research paper thumbnail of Evaluation of an artifact reduction strategy for electrically evoked auditory steady-state responses: Simulations and measurements

Journal of Neuroscience Methods

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Research paper thumbnail of Editorial: Understanding the Importance of Temporal Coupling of Neural Activities in Information Processing Underlying Action and Perception

Frontiers in Computational Neuroscience

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Research paper thumbnail of Auditory brainstem structures: brain canonical microcircuits for temporal processing?

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Research paper thumbnail of Loudness Perception and Dynamic Range Depending on Interphase Gaps of Biphasic Pulses in Cochlear Implants

Ear and Hearing

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Research paper thumbnail of Rate pitch discrimination in cochlear implant users with the use of double pulses and different interpulse intervals

Cochlear Implants International

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Research paper thumbnail of Increase in Mutual Information During Interaction of the Brain with Environment Contributes to Perception

Perception and motor interaction with physical surroundings can be analyzed by the changes in pro... more Perception and motor interaction with physical surroundings can be analyzed by the changes in probability laws governing two possible outcomes of neuronal activity, namely the presence or absence of spikes (binary states). Perception and motor interaction with physical environment are accounted partly by the reduction in entropy within the probability distributions of binary states of neurons in distributed neural circuits, given the knowledge about the characteristics of stimuli in physical surroundings. This reduction in the total entropy of multiple pairs of circuits in networks, by an amount equal to the increase of mutual information among them, occurs as sensory information is processed successively from lower to higher cortical areas or between different areas at the same hierarchical level but belonging to different networks. The increase in mutual information is partly accounted by temporal coupling as well as synaptic connections as proposed by Bahmer and Gupta [1]. We pro...

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Research paper thumbnail of Effects of electrical pulse polarity shape on intra cochlear neural responses in humans: Triphasic pulses with cathodic second phase

Hearing Research, Dec 1, 2013

Charge balanced pulses are used in modern cochlear implants to avoid direct current (DC) stimulat... more Charge balanced pulses are used in modern cochlear implants to avoid direct current (DC) stimulation that may damage neural tissues. In this context the effect of electrical pulse shape and polarity is still a matter of debate and the most effective pulse shape needs to be determined (Bahmer et al., 2010a; Undurraga et al., 2010; Wieringen et al., 2008; Macherey et al., 2008). Therefore, we conducted electrophysiological measurements, namely electrical compound action potentials (ECAPs) to assess response strength elicited by various pulse shapes and polarities in five cochlear implant recipients (SonataTI100/PulsarCI100 devices, MED-EL Innsbruck). ECAP response strength depending on pulse shape was compared with individual psychophysical thresholds. Results indicated the weakest response amplitude and highest thresholds for symmetric triphasic pulse shapes (with cathodic second phase), and the strongest response amplitude and lowest thresholds for biphasic pulses with anodic first phase. Biphasic pulses with cathodic first phase generated intermediate response amplitude and thresholds.

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Research paper thumbnail of Triphasic Pulses Reduce Facial Nerve Stimulation in CI Users: Intra- and Postoperative Electromyographic Data

Forschung heute – Zukunft morgen, 2018

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Using the Floating Mass Transducer (FMT) as a microphone – a possibility to develop a fully implantable CI?

Laryngo-rhino-otologie, Apr 1, 2018

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Computer simulation of chopper neurons

The aim of this work was to test a new model for oscillating neurons (chopper neurons) in the coc... more The aim of this work was to test a new model for oscillating neurons (chopper neurons) in the cochlear nucleus of the auditory system. In the beginning, it is shown that multiples of 0.4 ms are apparent in intrinsic oscillations in the auditory system and in pitch shift experiments. The existence of a time constant of 0.4 ms is explained by the assumption of a minimum chemical synaptic delay of this size between chopper neurons. The large dynamic range of periodicity coding, the small dynamic range of pure tone response, and the sharp frequency tuning of chopper neurons can be explained as a functional result of simultaneous projections from both the auditory nerve fibers and onset neurons to chopper neurons. As a consequence, the topology of the simulation of chopper neurons is as follows: To ensure the preference for multiples of 0.4 ms as observed in physiological and psychophysical experiments, chopper neurons are arranged in a circular network. The minimum number of two chopper...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Physiologically inspired coding strategies for cochlear implants

IFMBE Proceedings, 2009

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The Underlying Mechanism of Preventing Facial Nerve Stimulation by Triphasic Pulse Stimulation in Cochlear Implant Users Assessed With Objective Measure

Otology & Neurotology, 2016

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Application of triphasic pulses with adjustable phase amplitude ratio (PAR) for cochlear ECAP recording: II. Recovery functions

Journal of Neuroscience Methods, 2012

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Pitch Matching Psychometrics in Electric Acoustic Stimulation

Ear & Hearing, 2011

Combined electric-acoustic stimulation (EAS) is a therapeutic option for patients with severe to ... more Combined electric-acoustic stimulation (EAS) is a therapeutic option for patients with severe to profound mid- and high-frequency hearing loss while low-frequency hearing is mostly unaffected. The present study investigates bimodal pitch matching in EAS users as a function of the angular placement of electrodes. Results are compared with data obtained from previous pitch matching studies. Knowledge of electric and acoustic pitch mapping may be important for effective fitting to control the frequency range of acoustic and electric processing. Pitch adjustment experiments were conducted in eight subjects with residual hearing in the opposite ear as well as in the implanted ear. Four subjects received a standard 31.5-mm electrode array and four subjects received the shorter, more flexible 24-mm FLEX electrode array (PULSARCI100 or SONATATI100 stimulator, MED-EL, Innsbruck, Austria). The subjects' task was to listen to single-electrode stimuli presented at a fixed rate (800 pulses per second) via the cochlear implant and to adjust the frequency of the acoustic stimulus until the perceived pitch matched the perception of the electrically conveyed stimulus. Two to four of the most apical electrodes were tested depending on the range of the individual's residual hearing. Postoperative x rays (modified Stenver's view) were analyzed to compare individual pitch matching data in terms of the electrode arrays' insertion angle. The average mean frequency match for the most apical electrode 1 in EAS subjects implanted with the FLEX array was 583 Hz, while for the two subjects with a deep insertion of the 31.5-mm standard electrode array, the matches were 128 and 223 Hz. Because the residual hearing in the EAS subgroup was rather limited in the high-frequency range, a limited number of basal electrodes were assessed to determine the slope of the electric place/pitch function. A considerable variation in terms of the individual pitch function was observed. The slope of the pitch function varied to a large extent among subjects. The differences between contra- and ipsilateral adjustments were very small (mean average 14 Hz) and within the range of the variance (average SD 124 Hz). The application of a pitch matching procedure to assess the electric/acoustic crossover frequency is feasible. In the present study, ipsi- and contralateral pitch matches made by EAS patients were nearly equal; therefore, a severe alteration in the excitation pattern of the basilar membrane in the implanted ear can be ruled out.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Triphasische Pulse reduzieren Fazialisnervstimulation in CI-Nutzern: Intra- und postoperative elektromyographische Daten

Forschung heute – Zukunft morgen, 2018

Bookmarks Related papers MentionsView impact

Research paper thumbnail of New parallel stimulation strategies revisited: Effect of synchronous multi electrode stimulation on rate discrimination in cochlear implant users

Cochlear Implants International, 2013

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Role of affordance in perception Decoding Sensory Input

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Rate pitch discrimination with double pulse intervals optimized using ECAP responses

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Elektrisch-akustischer Tonhöhenvergleich

Bookmarks Related papers MentionsView impact

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

Hearing Research

Charge balanced pulses are used in modern cochlear implants to avoid direct current (DC) stimulat... more Charge balanced pulses are used in modern cochlear implants to avoid direct current (DC) stimulation that may damage neural tissues. In this context the effect of electrical pulse shape and polarity is still a matter of debate and the most effective pulse shape needs to be determined (Bahmer et al., 2010a; Undurraga et al., 2010; Wieringen et al., 2008; Macherey et al., 2008). Therefore, we conducted electrophysiological measurements, namely electrical compound action potentials (ECAPs) to assess response strength elicited by various pulse shapes and polarities in five cochlear implant recipients (SonataTI100/PulsarCI100 devices, MED-EL Innsbruck). ECAP response strength depending on pulse shape was compared with individual psychophysical thresholds. Results indicated the weakest response amplitude and highest thresholds for symmetric triphasic pulse shapes (with cathodic second phase), and the strongest response amplitude and lowest thresholds for biphasic pulses with anodic first phase. Biphasic pulses with cathodic first phase generated intermediate response amplitude and thresholds.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Evaluation of an artifact reduction strategy for electrically evoked auditory steady-state responses: Simulations and measurements

Journal of Neuroscience Methods

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Editorial: Understanding the Importance of Temporal Coupling of Neural Activities in Information Processing Underlying Action and Perception

Frontiers in Computational Neuroscience

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Auditory brainstem structures: brain canonical microcircuits for temporal processing?

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Loudness Perception and Dynamic Range Depending on Interphase Gaps of Biphasic Pulses in Cochlear Implants

Ear and Hearing

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Rate pitch discrimination in cochlear implant users with the use of double pulses and different interpulse intervals

Cochlear Implants International

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Increase in Mutual Information During Interaction of the Brain with Environment Contributes to Perception

Perception and motor interaction with physical surroundings can be analyzed by the changes in pro... more Perception and motor interaction with physical surroundings can be analyzed by the changes in probability laws governing two possible outcomes of neuronal activity, namely the presence or absence of spikes (binary states). Perception and motor interaction with physical environment are accounted partly by the reduction in entropy within the probability distributions of binary states of neurons in distributed neural circuits, given the knowledge about the characteristics of stimuli in physical surroundings. This reduction in the total entropy of multiple pairs of circuits in networks, by an amount equal to the increase of mutual information among them, occurs as sensory information is processed successively from lower to higher cortical areas or between different areas at the same hierarchical level but belonging to different networks. The increase in mutual information is partly accounted by temporal coupling as well as synaptic connections as proposed by Bahmer and Gupta [1]. We pro...

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