Cluster of Excellence Hearing4all

Hannover, Germany

Cluster of Excellence Hearing4all

Hannover, Germany
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Schierholz I.,Cluster of Excellence Hearing | Finke M.,Cluster of Excellence Hearing4all | Kral A.,Hannover Medical School | Buchner A.,Cluster of Excellence Hearing4all | And 3 more authors.
Human Brain Mapping | Year: 2017

There is substantial variability in speech recognition ability across patients with cochlear implants (CIs), auditory brainstem implants (ABIs), and auditory midbrain implants (AMIs). To better understand how this variability is related to central processing differences, the current electroencephalography (EEG) study compared hearing abilities and auditory-cortex activation in patients with electrical stimulation at different sites of the auditory pathway. Three different groups of patients with auditory implants (Hannover Medical School; ABI: n = 6, CI: n = 6; AMI: n = 2) performed a speeded response task and a speech recognition test with auditory, visual, and audio-visual stimuli. Behavioral performance and cortical processing of auditory and audio-visual stimuli were compared between groups. ABI and AMI patients showed prolonged response times on auditory and audio-visual stimuli compared with NH listeners and CI patients. This was confirmed by prolonged N1 latencies and reduced N1 amplitudes in ABI and AMI patients. However, patients with central auditory implants showed a remarkable gain in performance when visual and auditory input was combined, in both speech and non-speech conditions, which was reflected by a strong visual modulation of auditory-cortex activation in these individuals. In sum, the results suggest that the behavioral improvement for audio-visual conditions in central auditory implant patients is based on enhanced audio-visual interactions in the auditory cortex. Their findings may provide important implications for the optimization of electrical stimulation and rehabilitation strategies in patients with central auditory prostheses. © 2017 Wiley Periodicals, Inc.


Timm L.,Hannover Medical School | Vuust P.,University of Aarhus | Vuust P.,The Royal Academy of Music | Brattico E.,Aalto University | And 7 more authors.
Frontiers in Human Neuroscience | Year: 2014

Auditory processing in general and music perception in particular are hampered in adult cochlear implant (CI) users. To examine the residual music perception skills and their underlying neural correlates in CI users implanted in adolescence or adulthood, we conducted an electrophysiological and behavioral study comparing adult CI users with normal-hearing age-matched controls (NH controls). We used a newly developed musical multi-feature paradigm, which makes it possible to test automatic auditory discrimination of six different types of sound feature changes inserted within a musical enriched setting lasting only 20 min. The presentation of stimuli did not require the participants' attention, allowing the study of the early automatic stage of feature processing in the auditory cortex. For the CI users, we obtained mismatch negativity (MMN) brain responses to five feature changes but not to changes of rhythm, whereas we obtained MMNs for all the feature changes in the NH controls. Furthermore, the MMNs to deviants of pitch of CI users were reduced in amplitude and later than those of NH controls for changes of pitch and guitar timber. No other group differences in MMN parameters were found to changes in intensity and saxophone timber. Furthermore, the MMNs in CI users reflected the behavioral scores from a respective discrimination task and were correlated with patients' age and speech intelligibility. Our results suggest that even though CI users are not performing at the same level as NH controls in neural discrimination of pitch-based features, they do possess potential neural abilities for music processing. However, CI users showed a disrupted ability to automatically discriminate rhythmic changes compared with controls. The current behavioral and MMN findings highlight the residual neural skills for music processing even in CI users who have been implanted in adolescence or adulthood. Highlights: - Automatic brain responses to musical feature changes reflect the limitations of central auditory processing in adult Cochlear Implant users. - The brains of adult CI users automatically process sound features changes even when inserted in a musical context. - CI users show disrupted automatic discriminatory abilities for rhythm in the brain. - Our fast paradigm demonstrate residual musical abilities in the brains of adult CI users giving hope for their future rehabilitation. © 2014 Timm, Vuust, Brattico, Agrawal, Debener, Büchner, Dengler and Wittfoth.


PubMed | Hannover Medical School, Laser Zentrum Hannover e.V. and Cluster of Excellence Hearing4all
Type: | Journal: Scientific reports | Year: 2016

Optical stimulation of the cochlea with laser light has been suggested as an alternative to conventional treatment of sensorineural hearing loss with cochlear implants. The underlying mechanisms are controversially discussed: The stimulation can either be based on a direct excitation of neurons, or it is a result of an optoacoustic pressure wave acting on the basilar membrane. Animal studies comparing the intra-cochlear optical stimulation of hearing and deafened guinea pigs have indicated that the stimulation requires intact hair cells. Therefore, optoacoustic stimulation seems to be the underlying mechanism. The present study investigates optoacoustic characteristics using pulsed laser stimulation for in vivo experiments on hearing guinea pigs and pressure measurements in water. As a result, in vivo as well as pressure measurements showed corresponding signal shapes. The amplitude of the signal for both measurements depended on the absorption coefficient and on the maximum of the first time-derivative of laser pulse power (velocity of heat deposition). In conclusion, the pressure measurements directly demonstrated that laser light generates acoustic waves, with amplitudes suitable for stimulating the (partially) intact cochlea. These findings corroborate optoacoustic as the basic mechanism of optical intra-cochlear stimulation.


PubMed | Hannover Medical School, Leibniz Institute for Prevention Research and Epidemiology BIPS and Cluster of Excellence Hearing4all
Type: | Journal: Human brain mapping | Year: 2017

There is substantial variability in speech recognition ability across patients with cochlear implants (CIs), auditory brainstem implants (ABIs), and auditory midbrain implants (AMIs). To better understand how this variability is related to central processing differences, the current electroencephalography (EEG) study compared hearing abilities and auditory-cortex activation in patients with electrical stimulation at different sites of the auditory pathway. Three different groups of patients with auditory implants (Hannover Medical School; ABI: n = 6, CI: n = 6; AMI: n = 2) performed a speeded response task and a speech recognition test with auditory, visual, and audio-visual stimuli. Behavioral performance and cortical processing of auditory and audio-visual stimuli were compared between groups. ABI and AMI patients showed prolonged response times on auditory and audio-visual stimuli compared with NH listeners and CI patients. This was confirmed by prolonged N1 latencies and reduced N1 amplitudes in ABI and AMI patients. However, patients with central auditory implants showed a remarkable gain in performance when visual and auditory input was combined, in both speech and non-speech conditions, which was reflected by a strong visual modulation of auditory-cortex activation in these individuals. In sum, the results suggest that the behavioral improvement for audio-visual conditions in central auditory implant patients is based on enhanced audio-visual interactions in the auditory cortex. Their findings may provide important implications for the optimization of electrical stimulation and rehabilitation strategies in patients with central auditory prostheses. Hum Brain Mapp, 2017. 2017 Wiley Periodicals, Inc.


Lange F.,Hannover Medical School | Seer C.,Hannover Medical School | Finke M.,Cluster of Excellence Hearing4all | Finke M.,Hannover Medical School | And 2 more authors.
Biological Psychology | Year: 2015

Sokolov distinguished between reactive and proactive variants of the orienting response (OR). The Novelty P3 is considered as an electrophysiological signature of the reactive OR. Recent work suggests that the proactive OR is reflected in frontally distributed P3 activity elicited by uncertainty-reducing stimuli in task-switching paradigms. Here, we directly compare the electrophysiological signatures of reactive and proactive ORs. Participants completed a novelty oddball task and a task-switching procedure while the electroencephalogram was measured. Novel and uncertainty-reducing stimuli evoked prominent fronto-centrally distributed Novelty P3 and Uncertainty P3 waves, respectively. We found a substantial negative correlation between Novelty P3 and Uncertainty P3 across participants, suggesting that reactive and proactive ORs converge on a common neural pathway, but also that distinguishable routes to orienting exist. Moreover, response accuracy was associated with reduced Novelty-P3 and enhanced Uncertainty-P3 amplitudes. The relation between Novelty P3 and Uncertainty P3 might serve as an index of individual differences in distractibility and cognitive control. © 2015 Elsevier B.V.All rights reserved.


Chen L.-C.,Carl von Ossietzky University | Sandmann P.,Carl von Ossietzky University | Sandmann P.,Hannover Medical School | Thorne J.D.,Carl von Ossietzky University | And 5 more authors.
Brain Topography | Year: 2015

Functional near-infrared spectroscopy (fNIRS) has been proven reliable for investigation of low-level visual processing in both infants and adults. Similar investigation of fundamental auditory processes with fNIRS, however, remains only partially complete. Here we employed a systematic three-level validation approach to investigate whether fNIRS could capture fundamental aspects of bottom-up acoustic processing. We performed a simultaneous fNIRS-EEG experiment with visual and auditory stimulation in 24 participants, which allowed the relationship between changes in neural activity and hemoglobin concentrations to be studied. In the first level, the fNIRS results showed a clear distinction between visual and auditory sensory modalities. Specifically, the results demonstrated area specificity, that is, maximal fNIRS responses in visual and auditory areas for the visual and auditory stimuli respectively, and stimulus selectivity, whereby the visual and auditory areas responded mainly toward their respective stimuli. In the second level, a stimulus-dependent modulation of the fNIRS signal was observed in the visual area, as well as a loudness modulation in the auditory area. Finally in the last level, we observed significant correlations between simultaneously-recorded visual evoked potentials and deoxygenated hemoglobin (DeoxyHb) concentration, and between late auditory evoked potentials and oxygenated hemoglobin (OxyHb) concentration. In sum, these results suggest good sensitivity of fNIRS to low-level sensory processing in both the visual and the auditory domain, and provide further evidence of the neurovascular coupling between hemoglobin concentration changes and non-invasive brain electrical activity. © 2015, Springer Science+Business Media New York.


Stieghorst J.,Cluster of Excellence Hearing4all | Stieghorst J.,Hannover Medical School | Stieghorst J.,Leibniz University of Hanover | Tegtmeier K.,Cluster of Excellence Hearing4all | And 8 more authors.
Physica Status Solidi (A) Applications and Materials Science | Year: 2014

A self-bending electrode shaft for application in cochlear implants (CI) is presented. It is desired to reduce the distance between the electrode contacts and nerve cells in the modiolus of the inner ear. Therefore a coextrusion and overmolding device to fabricate a novel electrode shaft consisting of an eccentrically positioned hydrogel swelling actuator was established. Finite-element-analysis (FEA) was performed to analyse the self-bending effect in relationship to the applied hydrostatic pressure. The mechanical actuation of a fabricated electrode shaft was tested in vitro by injection of water into the hydrogel. Curving of the electrode shaft was observed. Osmotic pressure in relation to the mass fraction of the swelling polymer inside the hydrogel was calculated. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Stieghorst J.,Cluster of Excellence Hearing4all | Stieghorst J.,Hannover Medical School | Majaura D.,Cluster of Excellence Hearing4all | Majaura D.,Hannover Medical School | And 4 more authors.
ACS Applied Materials and Interfaces | Year: 2016

The direct fabrication of silicone-rubber-based individually shaped active neural implants requires high-speed-curing systems in order to prevent extensive spreading of the viscous silicone rubber materials during vulcanization. Therefore, an infrared-laser-based test setup was developed to cure the silicone rubber materials rapidly and to evaluate the resulting spreading in relation to its initial viscosity, the absorbed infrared radiation, and the surface tensions of the fabrication bed's material. Different low-adhesion materials (polyimide, Parylene-C, polytetrafluoroethylene, and fluorinated ethylenepropylene) were used as bed materials to reduce the spreading of the silicone rubber materials by means of their well-known weak surface tensions. Further, O2-plasma treatment was performed on the bed materials to reduce the surface tensions. To calculate the absorbed radiation, the emittance of the laser was measured, and the absorptances of the materials were investigated with Fourier transform infrared spectroscopy in attenuated total reflection mode. A minimum silicone rubber spreading of 3.24% was achieved after 2 s curing time, indicating the potential usability of the presented high-speed-curing process for the direct fabrication of thermal-curing silicone rubbers. (Figure Presented). © 2016 American Chemical Society.


PubMed | Cluster of Excellence Hearing4all
Type: Journal Article | Journal: International journal of audiology | Year: 2015

To report the development of a standardized German version of a reading span test (RST) with a dual task design. Special attention was paid to psycholinguistic control of the test items and time-sensitive scoring. We aim to establish our RST version to use for determining an individuals working memory in the framework of hearing research in German contexts.RST stimuli were controlled and pretested for psycholinguistic factors. The RST task was to read sentences, quickly determine their plausibility, and later recall certain words to determine a listeners individual reading span. RST results were correlated with outcomes of additional sentence-in-noise tests measured in an aided and an unaided listening condition, each at two reception thresholds.Item plausibility was pre-determined by 28 native German participants. An additional 62 listeners (45-86 years, M = 69.8) with mild-to-moderate hearing loss were tested for speech intelligibility and reading span in a multicenter study.The reading span test significantly correlated with speech intelligibility at both speech reception thresholds in the aided listening condition.Our German RST is standardized with respect to psycholinguistic construction principles of the stimuli, and is a cognitive correlate of intelligibility in a German matrix speech-in-noise test.


PubMed | Cluster of Excellence Hearing4all
Type: Journal Article | Journal: ACS applied materials & interfaces | Year: 2016

The direct fabrication of silicone-rubber-based individually shaped active neural implants requires high-speed-curing systems in order to prevent extensive spreading of the viscous silicone rubber materials during vulcanization. Therefore, an infrared-laser-based test setup was developed to cure the silicone rubber materials rapidly and to evaluate the resulting spreading in relation to its initial viscosity, the absorbed infrared radiation, and the surface tensions of the fabrication beds material. Different low-adhesion materials (polyimide, Parylene-C, polytetrafluoroethylene, and fluorinated ethylenepropylene) were used as bed materials to reduce the spreading of the silicone rubber materials by means of their well-known weak surface tensions. Further, O2-plasma treatment was performed on the bed materials to reduce the surface tensions. To calculate the absorbed radiation, the emittance of the laser was measured, and the absorptances of the materials were investigated with Fourier transform infrared spectroscopy in attenuated total reflection mode. A minimum silicone rubber spreading of 3.24% was achieved after 2 s curing time, indicating the potential usability of the presented high-speed-curing process for the direct fabrication of thermal-curing silicone rubbers.

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