Biology subjects

Moser, T.

Publications and source records attributed to Moser, T..

At least 19 recordsLinked to original sources

bioRxiv2026

In silico framework for benchmarking optogenetic hearing restoration

Cochlear implants (CI) partially restore hearing in profoundly hearing impaired or deaf people by electrically stimulating the auditory nerve. A bottleneck of electrical CIs is the broad spread of electrical current from each electrode that limits the transfer of spectral information, which might be overcome by future spatially confined optogenetic stimulation. Here we established an in silico framework, FraSCO, to model sound encoding in the human cochlea by an optogenetic CI (oCI) for testing the potential of optogenetic hearing restoration. The biophysical modeling framework combined an optical raytracing model implementing a human cochlea implanted with a waveguide-based oCI with a single compartment model of optogenetically modified spiral ganglion neurons (SGNs). The input was an optogenetic sound coding strategy and the quality of the neural representation was evaluated based on comparison of neurograms evoked by optogenetic and electrical stimulation to the spectrogram of the sound applied. The model aimed for technologically feasible properties of the oCIs with 64 stimulation channels. The biophysical modeling framework successfully captured essential physiological features of optogenetic SGN stimulation with a minimal set of ion channel types expressed in the SGN soma. Working with a sample of 1000 SGNs distributed along the tonotopic axis to represent sound encoding, we found that improved spectral selectivity more than compensates for lower temporal fidelity of current implementations of optogenetic stimulation. The established computational framework enables in silico investigation and benchmarking of sound encoding in the cochlea by future oCI and state-of-the-art eCI. The results indicate that optogenetic sound encoding has potential to improve speech understanding in noisy environments for CI users.

neuroscience↗

bioRxiv2026

Visual exoproteomics of Clostridium thermocellum during anaerobic biomass-degradation identifies functional spirosomes

Visual proteomics enables the study of low-abundance proteins and identification of unknown complexes from heterogeneous samples by complementing high-resolution cryogenic electron microscopy (cryoEM) with external inputs on protein identity such as mass spectrometry. Using this approach, we interrogated the exoproteome of the anaerobic cellulose-degrading bacterium Clostridium thermocellum as it carried out biomass degradation. Mass spectrometry indicated a broad exoproteome composition, including cellulose degrading machinery CelA and CipA. A focus on large exoproteome assemblies revealed abundant protein filaments and pleomorphic vesicular structures. Analysis of the most abundant protein filaments yielded an [~]4 {square} resolution native structure that, aided by mass spectrometry, de novo modeling, and structural searching, was found to be the aldehyde-alcohol dehydrogenase (AdhE) spirosome. AdhE contained both NAD+ and Fe in their expected binding sites and biochemical and structural analyses of enriched spirosome preparations indicated they were functional. Altered NADH solution concentrations triggered conformational changes in the exoproteomic spirosomes, and the constituent AdhE remained capable of ethanol production. Although the basis for functional extracellular spirosome accumulation in live anaerobic C. thermocellum cultures remains unclear, their abundance in crude exoproteomes suggests their presence could influence biomass fueled C. thermocellum growth.

biochemistry↗

bioRxiv2026

Multichannel optical cochlear implants enable spectrally distinct auditory activity

When hearing fails, cochlear implants (CIs) restore auditory perception. Yet, coding of spectral information remains a bottleneck because each electrode broadly activates the auditory nerve. As light can be more conveniently confined, optical (o)CIs present an alternative. Here, we combined expression of the potent channelrhodopsin ChReef in spiral ganglion neurons (SGNs) with oCIs comprising 5-10 green LEDs in gerbils. This combination enabled systematic comparison of encoding intensity and spectral information by individual oCI channels to acoustic and electrical stimulation within a translationally feasible energy range. Recordings from the inferior colliculus (ICC) showed that ChReef aligned SGN light sensitivity with LED radiant fluxes: ICC activity had thresholds <200 nJ and reached a maximum equivalent to that achieved with 51 dB SPL pure tones. Multichannel oCIs enabled tonotopically ordered, spectrally distinct stimulation that more closely resembled acoustic stimulation than did electrical stimulation. Some LEDs elicited multiple spectral peaks at higher intensities. Linear discriminant analysis of ICC activity indicated improved channel discriminability for optical over electrical stimulation. In summary, ,micro-joule oCI-stimulation achieves improved spectral resolution over state-of-the-art electrical stimulation.

neuroscience↗

bioRxiv2026

Optogenetic cochlear stimulation evokes midbrain activity with near-physiological temporal fidelity

When hearing fails, stimulation of the auditory nerve by electrical cochlear implants (eCIs) partially restores hearing, with most eCI users achieving open speech understanding. However, the broad current spread from each electrode limits frequency coding and speech understanding in daily situations with background noise. Spatially confined optogenetic stimulation by future optical cochlear implants (oCIs) improves frequency coding but millisecond closing kinetics of channelrhodopsins (ChRs) might limit temporal coding. Here, we evaluated the utility of fast-closing f-Chrimson for processing temporal information in the auditory system of Mongolian gerbils. We recorded neural activity in the inferior colliculus evoked by f-Chrimson-mediated optogenetic stimulation of the cochlea. F-Chrimson enabled energy-efficient stimulation of the auditory pathway at rates [≥]150 Hz, outperforming the slower ChR variants CatCh (blue) and ChReef (green). Energy thresholds for activation of the auditory pathway were in the low {micro}J range, between ChReef (sub-{micro}J) and CatCh. Dynamic range and frequency selectivity were comparable to previous observations with CatCh and outperformed electrical stimulation. In conclusion, employing fast-gating ChRs harnesses improved spectral coding without degrading temporal coding. The Paper Explained ProblemElectrical cochlear implants (eCIs) partially restore speech comprehension in most of 1 million otherwise severely deaf people. However, most CI-users face challenges hearing in daily situations. Spectrally more selective stimulation of the auditory nerve by optical cochlear implants (oCIs) promises to overcome this limitation. However, the closing kinetics of channelrhodopsins (ChR) limit the temporal bandwidth of bionic sound coding. Improving the ChR properties and evaluating temporal coding remain major objectives for developing hearing restoration by oCI. ResultsHere, we evaluate the utility of waveguide-based oCI using the fast-closing ChR Chrimson (f-Chrimson) for encoding of temporal, spectral and intensity information by multi-electrode-array (MEA) recordings from the midbrain. We compare f-Chrimson-mediated bionic coding to acoustic coding as well as to previous data acquired with optogenetic stimulation using other ChRs and with electrical stimulation. F-Chrimson enabled energy-efficient stimulation of the auditory pathway at rates [≥]150 Hz, outperforming the slower ChR variants CatCh (blue) and ChReef (green). Intensity and frequency coding were comparable to previous observations with CatCh and outperformed electrical stimulation. ImpactThis study demonstrates near physiological temporal coding with the fast-closing ChR f-Chrimson, indicating that improved spectral coding by oCI is not traded off by poor temporal fidelity.

neuroscience↗

bioRxiv2026

Reference-free microsatellite instability detection from tumor sequencing using intrasample variability modeling

Microsatellite instability (MSI) is a key predictive biomarker across multiple tumor types, but current next-generation sequencing (NGS)-based callers oftendependon matched normals, large reference panels, or pretrained machine-learning models, which limits portability across assays and sequencing centers. We developed PROMIS (PROfiling of Microsatellite InStability), a tumor-only, reference-free pipeline that detects MSI by leveraging intrasample variability at predefined microsatellite loci. PROMIS models repeat-length distributions with a discrete mixture framework to distinguish stable germline configurations from unstable loci with additional allele populations. Locus-level classifications are aggregated into a continuous MSI score, defined as the fraction of unstable loci, which can then be used to classify samples as MSI-high or microsatellite-stable. We benchmarked PROMIS in colorectal (CRC), endometrial (UCEC), and gastric (STAD) cancers from The Cancer Genome Atlas (TCGA). PROMIS achieved an overall AUC of 0.995 and cohort-specific AUCs of 1.00 in CRC and STAD and 0.999 in UCEC, comparable to establi shed tools despite not using matched normals or pretrained models. Subsampling and in silico dilutions showed robust performance with substantially fewer loci and down to 3% tumor fraction. Finally, in prostate and CRC cell-free DNA (cfDNA) cohorts, including Illumina TSO500 data and an 18-gene panel, PROMIS yielded assay-agnostic MSI scores concordant with orthogonal tissue- and panel-based classifications.

bioinformatics↗

bioRxiv2025

CochleaNet: deep learning-based image analysis for cochlear connectomics and gene therapy

With the emergence of gene and optogenetic therapies targeting deafness, the comprehensive analysis of the molecular anatomy and physiology of the cochlea has become ever more important. Here, we introduce CochleaNet, a deep learning-based framework to analyze volumetric imaging data obtained by light-sheet microscopy of decalcified, cleared and fluorescently labeled cochleae. CochleaNet covers the workflow from reconstruction of the cochlea to segmentation of inner hair cells, spiral ganglion neurons and their afferent synapses, to analyzing the expression of gene therapy products. We validated CochleaNet by comparison to manual image analysis. Trained on high isotropic resolution mouse data, CochleaNet was also applicable to the cochlea of the gerbil, another relevant animal model, and lower-resolution mouse data from a commercially available microscope. We conclude that the combination of light-sheet microscopy and image analysis with CochleaNet paves the way for rapid and reliable quantification of cochlear molecular anatomy and preclinical gene therapy outcomes.

neuroscience↗

bioRxiv2025

Structure and function of otoferlin, a synaptic protein of sensory hair cells essential for hearing

Our sense of hearing relies upon speedy synaptic transmission of sound information from cochlear inner hair cells (IHCs) to spiral ganglion neurons (SGNs). To accomplish this, IHCs employ a sophisticated presynaptic machinery including the multi-C2-domain protein otoferlin which is affected by human deafness mutations. Otoferlin is essential for IHC-exocytosis but how it binds Ca2+ and the target membrane to serve synaptic vesicle (SV) tethering, docking and fusion remained unclear. Here, we obtained cryo-electron-microscopy structures of Ca2+-bound otoferlin and employed molecular dynamics simulations of membrane binding. We show that membrane binding involves C2B-C2G-domains and repositions C2F- and C2G-domains. Progressive disruption of Ca2+-binding by the C2D-domain in mice increasingly altered synaptic sound encoding and eliminated the Ca2+-cooperativity of SV-exocytosis, indicating that this Ca2+-cooperativity reflects binding of several Ca2+-ions to otoferlin. Together, our findings elucidate molecular mechanisms underlying otoferlin-mediated SV-docking and support a role of otoferlin as Ca2+-sensor of SV-fusion in IHCs.

neuroscience↗

bioRxiv2025

Charting the nanotopography of inner hair cell synapses using MINFLUX nanoscopy

For us to hear, the cochlea encodes sounds into neural signals at synapses of inner hair cells (IHCs) and the auditory nerve with remarkable fidelity. To achieve the high rates of temporally precise synaptic transmission over long periods of time, IHCs employ sophisticated ribbon-type active zones (AZ). In order for us to understand synaptic sound encoding, we need to decipher the underpinning molecular topography of these synapse which had remained challenging due to technological limitations. Here we applied 3-dimensional minimal flux optical nanoscopy to mouse IHC synapses to chart the position of key pre- and postsynaptic proteins with single digit nanometre resolution of imaging. We demonstrate that nanoclusters of channels and interacting proteins govern the topography of AZs and postsynaptic densities (PSDs). We count synaptic proteins, their nanoclusters and determine their spatial organization feeding into computational modelling of AZ function. In conclusion, this study reveals a nanocluster-based molecular AZ and PSD topography, likely serving as functional modules in synaptic sound encoding.

neuroscience↗

bioRxiv2025

Isotropic, aberration-corrected light sheet microscopy for rapid high-resolution imaging of cleared tissue

Light sheet microscopy is the ideal technique for multiscale imaging of large and cleared tissues, and it is desirable to achieve the highest possible isotropic resolution across the entire sample. However, isotropic resolution for a centimeter-sized sample has only been achieved with slow and often aberrated, axially scanned light sheets, resulting in a low resolution of several micrometers. Here, we introduce a compact, high-speed light sheet fluorescence microscope with isotropic sub-micron resolution optimized for cleared tissue. We introduce three major opto-mechanical innovations using off-the-shelf optics to achieve an isotropic resolution of 850 nm across samples up to 1 cm3 and refractive indices ranging from 1.33 to 1.56, using mechanical tiling with a field of view of 800 {micro}m x 800 {micro}m. We show that combining an air objective and a meniscus lens achieves an axially swept light sheet with sub-micron diffraction-limited resolution and aberration correction. The effective field of view is increased 2-fold by correcting the field curvature of the light sheet with a concave mirror in the remote focusing unit. Furthermore, the imaging speed is enhanced 10-fold by adapting the light sheets motion with a closed-loop feedback, reaching 100 frames per second while maintaining isotropic resolution across the large field of view. Finally, we showcase the performance of our light sheet system for imaging from subcellular up to centimeter scale in cleared zebrafish, mouse cochlea, and mouse brain using various clearing methods.

developmental biology↗

bioRxiv2025

Neuromodulation of the endbulb of Held synapse in the cochlear nucleus

Synapses vary greatly in synaptic strength and plasticity, even within the same circuitry or set of pre- and postsynaptic neurons. Neuromodulation is a candidate mechanism to explain some of this variability. Neuromodulators such as monoamines can differentially regulate presynaptic function as well as neuronal excitability. Variability is found also for the large calyceal synapses of the auditory pathway that are endowed with high synaptic vesicle (SV) release probability (Pvr) and large postsynaptic currents enabling reliable and temporally precise transmission of auditory information. Here we investigated whether the calyceal endbulb of Held synapse formed by auditory nerve fibers onto bushy cells (BCs) in the anteroventral cochlear nucleus (AVCN) is modulated by norepinephrine (NE) and serotonin (5-HT). Using electron microscopy (EM) of the cochlear nucleus we found evidence for putative monoaminergic varicosities in both ventral and dorsal divisions. Immunostaining for vesicular 5-HT and NE transporters revealed NE-containing and 5-HT-containing varicosities in the AVCN, juxtaposed to both endbulbs and BCs. Furthermore, we detected immunofluorescence for 5-HT1B, 5-HT4, 5-H7 receptors (R) and 2C-adrenergic receptors (AR) in BCs. We used voltage-clamp recordings from mouse BCs in order to uncover potential presynaptic effects of neuromodulation, which revealed an increase in frequency of miniature excitatory postsynaptic currents (mEPSCs) upon application of NE but not 5-HT. Evoked synaptic transmission was unaffected by the application of either NE or 5-HT. Likewise, while studying the biophysical properties of the BCs, we did not observe effects of NE or 5-HT on low-voltage-activated K+ (K+LVA) and hyperpolarization-activated mixed cation (HCN) channels during application. In summary, we report evidence for the presence of monoaminergic innervation in the cochlear nucleus and for subtle functional NE-neuromodulation at the endbulb of Held synapse.

neuroscience↗

bioRxiv2025

Structural Basis of Lipid Membrane Binding by Human Ferlins

Ferlins, ancient membrane proteins with a unique architecture, are central to multiple essential, Ca2+-dependent vesicle fusion processes. Despite numerous functional studies and their link to burdening human diseases, a mechanistic understanding of how these multi-C2 domain proteins interact with lipid membranes to promote their remodeling and fusion is currently lacking. Here, we elucidate the near-complete cryo-electron microscopy structures of human myoferlin and dysferlin in their Ca2+ and lipid-bound states. We show that ferlins adopt compact, ring-like tertiary structures achieved upon membrane binding. The top arch of the ferlin ring, comprising the C2C-C2D region, is rigid and varies little across the observed functional states. In contrast, the N-terminal C2B and the C-terminal C2F-C2G domains cycle between alternative conformations and, in response to Ca2+, close the ferlin ring, promoting tight interaction with the target membrane. Probing key domain interfaces validates the observed architecture and informs a model of how ferlins engage lipid bilayers in a Ca2+- dependent manner. This work reveals the general principles of human ferlin structures and provides a framework for future analyses of ferlin-dependent cellular functions and disease mechanisms.

biochemistry↗

bioRxiv2025

Gating of hair cell Ca2+ channels governs the activity of cochlear neurons

Our sense of hearing processes sound intensities spanning six orders of magnitude. In the ear, postsynaptic spiral ganglion neurons (SGNs) tile this intensity range with their firing rate codes. Presynaptic inner hair cells (IHCs) vary Ca2+-influx among their active zones (AZs) diversifying glutamate release and likely contributing to SGN firing diversity. Here we show that low-voltage activation of IHC-Ca2+-influx of mice, modeling the human CaV1.3A749G mutation, increases spontaneous SGN-firing and lowers sound threshold. Altered synaptic morphology in CaV1.3A749G/A749G mice already at ambient sound levels of standard mouse husbandry indicates a risk for noise-induced alterations in CaV1.3A749G patients. We conclude that heterogeneous voltage-dependence of CaV1.3 activation among IHC-AZs contributes to the diversity of SGN firing for sound intensity coding and synaptic vulnerability.

neuroscience↗

bioRxiv2024

SynapseNet: Deep Learning for Automatic Synapse Reconstruction

Electron microscopy is an important technique for the study of synaptic morphology and its relation to synaptic function. The data analysis for this task requires the segmentation of the relevant synaptic structures, such as synaptic vesicles, active zones, mitochondria, presynaptic densities, synaptic ribbons, and synaptic compartments. Previous studies were predominantly based on manual segmentation, which is very time-consuming and prevented the systematic analysis of large datasets. Here, we introduce SynapseNet, a tool for the automatic segmentation and analysis of synapses in electron micrographs. It can reliably segment synaptic vesicles and other synaptic structures in a wide range of electron microscopy approaches, thanks to a large annotated dataset, which we assembled, and domain adaptation functionality we developed. We demonstrated its capability for (semi-)automatic biological analysis in two applications and made it available as an easy-to-use tool to enable novel data-driven insights into synapse organization and function.

bioinformatics↗

bioRxiv2024

Improved optogenetic modification of the spiral ganglion neurons for future optical cochlear implants

Optogenetic stimulation has become a promising approach for restoring lost body function. For example, partial restoration of vision has been achieved in a blind patient and proof-of-concept has been demonstrated for optogenetic hearing restoration in rodents. In order to prepare clinical translation of hearing restoration, efficient and safe optogenetic modification of spiral ganglion neurons (SGNs) in the mature cochlea remains to be developed. Here, we established microcatheter-based administration adeno-associated virus (AAV) to scala tympani of the cochlea of Mongolian gerbils and compared it to the previously developed AAV-injection into the spiral ganglion. We probed the potential AAV-PHP.S capsid to express channelrhodopsins (ChRs) under the control of the human synapsin promotor in mature SGNs in hearing and deafened gerbils. Using the microcatheter approach, but not with the AAV-modiolus injection, we achieved reliable ChR expression in SGN enabling optogenetic stimulation of the auditory pathway in 80% of the treated animals. Yet, the efficiency of SGN transduction was modest with only [~]30% ChR-expressing SGNs. Moreover, we encountered off-target expression in hair cells in hearing gerbils in both approaches, but not ChR expression in the central nervous system using microcatheter administration. Comparing optogenetic auditory brainstem responses of gerbils with and without hair cell transduction confirmed that SGNs were the primary site of optogenetic stimulation of the pathway.

neuroscience↗

bioRxiv2024

Probing the role of Nogo receptor homolog NgR2 in setting up cochlear connectivity

Sound encoding depends on the precise and reliable neurotransmission at the afferent synapses between the sensory inner hair cells (IHCs) and spiral ganglion neurons (SGNs). The molecular mechanisms contributing to the formation, as well as interplay between the pre- and postsynaptic components remain largely unclear. Here, we tested the role of the synaptic adhesion molecule and Nogo/RTN4 receptor homolog RTN4RL2 (also referred to as NgR2) in the development and function of afferent IHC-SGN synapses. Upon deletion of RTN4RL2 in mice (RTN4RL2-/-), presynaptic IHC active zones showed enlarged synaptic ribbons and a depolarized shift in the activation of CaV1.3 Ca2+ channels. The postsynaptic densities (PSDs) of SGNs were smaller and deficient of GluA2-4 AMPA receptor subunits despite maintained Gria2 mRNA expression in SGNs. Next to synaptically engaged PSDs we observed "orphan" PSDs located away from IHCs. They likely belong to a subset of SGN peripheral neurites that do not contact the IHCs in RTN4RL2-/- cochleae as found by volume electron microscopy reconstruction of SGN neurites. Auditory brainstem responses of RTN4RL2-/- mice showed increased sound thresholds indicating impaired hearing. Together, these findings suggest that RTN4RL2 contributes to the proper formation and function of auditory afferent synapses and is critical for normal hearing.

neuroscience↗

bioRxiv2024

Establishing synthetic ribbon-type active zones in a heterologous expression system

Encoding of several sensory modalities into neural signals is mediated by ribbon synapses. The synaptic ribbon tethers synaptic vesicles at the presynaptic active zone (AZ) and may act as a super-scaffold organizing AZ topography. Here we employed a synthetic biology approach to reconstitute structures mimicking ribbon-type AZs in HEK293 cells for probing minimal molecular requirements and studying presynaptic Ca2+ channel clustering. Co-expressing a membrane-targeted version of the AZ-protein Bassoon and the ribbon core protein RIBEYE, we observed structures recapitulating basic aspects of ribbon-type AZs, which we call synthetic ribbons or SyRibbons. Super-resolution STED microscopy and cryo-correlative electron tomography revealed SyRibbons were similar to native ribbons at AZs of cochlear inner hair cells in shape and size. SyRibbons with Ca2+ channel clusters formed upon additional expression of CaV1.3 Ca2+ channels and RIM-binding protein 2 (RBP2). CaV1.3 Ca2+ channel clusters associated with SyRibbons were larger than ribbonless CaV1.3 Ca2+ channels clusters and functional analysis by Ca2+-imaging in combination with patch clamp showed partial confinement of the Ca2+ signal at SyRibbons. In summary, we identify Ca2+ channels, RBP, membrane-anchored Bassoon, and RIBEYE as minimal components for reconstituting a basic ribbon-type AZ. SyRibbons might complement animal studies on molecular interactions of AZ proteins. Significance StatementEncoding of sensory information in our eyes and ears builds on specialized ribbon synapses of sensory cells. Elucidating the molecular underpinning of their fascinating structure and function is an ongoing effort to which we add a bottom-up reconstitution approach in cultured cells. Aiming to recapitulate basic properties of ribbon-type presynaptic active zones of cochlear inner hair cells, we identified a minimal set of proteins that assemble in cellular nanodomains, structurally and functionally alike active zones. While not yet reconstituting synaptic vesicle exocytosis, we consider the established synthetic ribbon-type active zones a valuable platform for studying molecular interactions of active zone proteins. We expect the approach to complement and reduce experiments on native ribbon synapses asserted from animals.

neuroscience↗

bioRxiv2024

CryoRhodopsins: a comprehensive characterization of a new clade of microbial rhodopsins from cold environments

Microbial rhodopsins are omnipresent on Earth, however the vast majority of them remain uncharacterized. Here we describe a new rhodopsin group from cold-adapted organisms and cold environments, such as glaciers, denoted as CryoRhodopsins (CryoRs). Our data suggest that CryoRs have dual functionality switching between inward transmembrane proton translocation and photosensory activity, both of which can be modulated with UV light. CryoR1 exhibits two subpopulations in the ground state, which upon light activation lead to transient photocurrents of opposing polarities. A distinguishing feature of the group is the presence of a buried arginine residue close to the cytoplasmic face of its members. Combining single-particle cryo-electron microscopy and X-ray crystallography with the rhodopsin activation by light, we demonstrate that the arginine stabilizes a UV-absorbing intermediate of an extremely slow CryoRhodopsin photocycle. Together with extensive spectroscopic characterization, our investigations on CryoR1 and CryoR2 proteins reveal mechanisms of photoswitching in the newly identified group and demonstrate principles of the adaptation of these rhodopsins to low temperatures.

biophysics↗

bioRxiv2023

Efficient and sustained optogenetic control of nervous and cardiac systems

Optogenetic control is used to manipulate the activity of specific cell types in vivo for a variety of biological and clinical applications. Here we report ChReef, an improved variant of the channelrhodopsin ChRmine. ChReef offers minimal photocurrent desensitization, a unitary conductance of 80 fS and closing kinetics of 30 ms, which together enable reliable optogenetic control of cells at low light levels with good temporal fidelity and sustained stimulation. We demonstrate efficient and reliable red-light pacing and depolarization-block of ChReef-expressing cardiomyocyte clusters. We used AAV-based gene transfer to express ChReef in retinal ganglion cells, where it restores visual function in blind mice with light sources as weak as an iPad screen. Toward optogenetic hearing restoration, ChReef enables stimulation of the auditory pathway in rodents and non-human primates with nano-Joule threshold, enabling efficient and frequency-specific stimulation by LED-based optical cochlear implants.

biophysics↗