ABR/DPOAE publications

Ménière's disease (MD), a chronic inflammatory disorder with age‐related increased incidence, exhibits poorly understood pathogenesis and limited therapeutic options. Here, we demonstrate that cellular senescence, marked by mitochondrial damage, reactive oxygen species accumulation, and senescence‐associated secretory phenotype (SASP), is prevalent in the vestibular tissue of MD patients and an endolymphatic hydrops mouse model. The transcription factor GATA4 is upregulated in MD and mice, and its genetic deletion in hair cells alleviates LPS‐induced audio‐vestibular dysfunction and cellular senescence in mice and HEI‐OC1 cells. Mechanistically, HDAC6 interacts with GATA4 and restrains its nuclear transport, while RNA‐seq and ChIP‐seq identify HtrA1, a serine protease, as a direct transcriptional target of GATA4. Inhibition of HDAC6 or AAV‐mediated HtrA1 overexpression exacerbates MD‐like symptoms, whereas inhibition of HtrA1 by Galegenimab ameliorates these phenotypes in mice. In aged mice, GATA4 deletion reduces age‐related audio‐vestibular deficits and senescence markers. Collectively, our findings establish GATA4 as a critical regulator of cellular senescence and inflammaging in inner ear pathologies, providing promising therapeutic targets for MD and age‐related audio‐vestibular disorders.

The molecular and cellular mechanisms underlying the function of the cochlear nucleus (CN) remain to be fully elucidated. Using single-nucleus RNA sequencing and single-cell spatial transcriptome analyses, we generated a comprehensive cell type atlas of the mouse CN, identified molecularly defined CN subregions, and quantified changes in gene expression and the spatial organization of CN cells in normal mice during postnatal development and in mutant mice with congenital hearing loss. We further identified a subtype of bushy cells expressing the osteopontin-encoding gene Spp1 as the primary CN cell type that exhibited hearing loss-induced alteration of gene expression. Among the highly affected genes in bushy cells, deletion of the auditory input-regulated gene Spp1 affected CN processing of auditory signals in mice. These results provide the most comprehensive cellular and molecular database to date for understanding auditory processing within the CN and identifying potential therapeutic targets for hearing restoration at the CN level.

Background: Kölliker’s organ (KO) support cells undergo orderly, time-dependent degeneration that is essential for auditory development and is accompanied by precisely regulated autophagic activity; however, the molecular hierarchy linking autophagy to this remodeling remains obscure. This study aimed to elucidate the regulatory mechanisms connecting autophagic flux to lysosomal biogenesis and auditory function during cochlear development. Method: We established an Atg5flox/flox; Sox2Cre+ mouse model with deletion of the autophagy gene Atg5 in cochlear-supporting cells. Auditory function was assessed via Auditory Brainstem Response (ABR) testing. Transcriptomic profiling of the neonatal basilar membrane was performed to screen for downstream targets. Mechanistic validation included spatiotemporal immunofluorescence mapping (E18–P30) and in vitro functional assays using siRNA-mediated knockdown and lysosomal tracking. Results: At 2 months of age, Atg5flox/flox; Sox2Cre+ mice exhibited moderate-to-severe sensorineural hearing loss accompanied by significant outer hair cell loss. Bulk RNA-seq of the basilar membrane identified fork-head box A3 (Foxa3) as a significantly downregulated transcription factor within the lysosomal–autophagy network. Spatiotemporal immunolabelling from embryonic day 18 to postnatal day 30 revealed that FOXA3 expression becomes progressively restricted to KO cells during postnatal development, with ATG5 loss reducing FOXA3 protein levels by 62.4%. In vitro, deficiency of either Atg5 or Foxa3 in primary KO cells resulted in comparable reductions in LAMP1-positive puncta. Conclusions: These findings support a model wherein the ATG5-FOXA3 axis contributes to lysosomal biogenesis in developing KO cells, with implications for understanding mechanisms of congenital sensorineural hearing loss.

Approximately 50% of hereditary deafness cases and most age-related hearing loss result from cochlear hair cell dysfunction. Adeno-associated virus (AAV)-mediated gene therapy offers a promising strategy for hearing restoration. However, the cochlea's complex cellular composition poses a significant challenge for targeted gene delivery into hair cells. Here, we establish a cross-species screening platform for cochlear AAV tools, applicable from rodents to large animals. Using this platform, we identify human promoters that specifically target inner hair cells, outer hair cells, or all hair cells in mice. The hair cell-specific coProB2 promoter is further validated in Bama miniature pigs and cynomolgus monkeys, achieving specific transgene expression in hair cells without auditory toxicity. Importantly, coProB2-driven gene therapies in DFNB79 and DFNB9 mouse models restore auditory function to near wild-type levels. Thus, this study establishes a cross-species-compatible, hair cell-specific AAV system, providing a versatile toolbox for cochlear hair cell gene therapy.

Background: Genetic diagnosis plays a critical role in enhancing the identification and clinical management of pediatric hearing loss, ultimately improving both physiological outcomes and social-emotional development. As one of the most prevalent sensory disorders characterized by substantial genetic heterogeneity, hearing loss requires the implementation of efficient diagnostic approaches to inform targeted clinical interventions and personalized care strategies. Methods: Here, we recruited 3353 Han Chinese children with nonsyndromic hearing loss, including 598 multiplex cases with family history. We employed SNPscan, targeted panel sequencing (TPS), and whole-exome sequencing (WES) to delineate the mutation landscape. Findings: Utilizing a tiered genomic testing strategy, we performed SNPscan for all 3353 participants, TPS for 675 cases, and WES for 204 multiplex cases. We achieved an overall diagnostic yield of 48.3% (1620/3353) in this cohort. Our analysis identified 87 previously unreported variants across 24 genes, including a de novo FOXI1 mutation (c.479_481del) linked to Mondini malformation and enlarged vestibular aqueduct, validated through knock-in mouse models. Additionally, we discovered NEU4 as a candidate gene related to hearing loss, with knockout mice and cellular models demonstrating its role in auditory dysfunction via disrupted neuraminidase activity and axonal development. These findings enrich the spectrum of deafness-related genes and provide a new theoretical foundation for diagnosing hearing loss. Interpretation: This study not only expands the genetic spectrum of hearing loss but also underscores the clinical utility of advanced sequencing in guiding precision therapies and early syndromic surveillance. This study offers a detailed characterization of the genetic landscape of pathogenic variants associated with hearing loss in the Han Chinese population, which will contribute to the design of a cost-effective genetic screening scheme, and also provides valuable insights that contribute to the global understanding of the genetics of hearing loss. Funding: This work was supported by the Key Program of National Natural Science Foundation of China, the National Key Research and Development Program of China, the National Natural Science Foundation of China and the Major Fundamental Research Program of the Natural Science Foundation of Shandong Province, China.

Noise exposures causing transient hearing loss were previously considered benign. However, recent work has revealed that temporary noise-induced threshold shifts may be associated with long-lasting cochlear histopathology. One such effect is cochlear synaptopathy, i.e. changes to the afferent synapse between inner hair cells and auditory nerve fibers. Noise-induced synaptopathy has been extensively characterized in several rodent models, and temporal bone studies suggest similar age-related changes in humans. However, it remains unclear how noise-induced temporary threshold shifts affect cochlear structures in humans and nonhuman primates, which show greater resistance to noise exposure than other animals. Additionally, the long-term sequelae of temporary threshold shifts are largely unknown. Here, we characterized the effects of a noise exposure causing temporary threshold shifts on cochlear histopathology in macaque monkeys at long post-exposure survival times. Overall, cochlear histopathology was variable across subjects, similar to the variable susceptibility observed in humans. At 2 and 10 months post-exposure, macaques had no significant loss of hair cells, inner hair cell synapses, or cholinergic efferent innervation. However, both inner and outer hair cell ribbons showed significant enlargement. Together, these findings provide insight into the cochlear effects of single-exposure temporary threshold shifts in nonhuman primates.

Aminoglycoside antibiotics remain crucial for the treatment of severe infections caused by multidrug-resistant bacteria; however, their clinical use is limited by the risk of irreversible hearing loss. Previous studies have primarily attributed aminoglycoside-induced hearing loss to cochlear hair cell loss and subsequent spiral ganglion degeneration, while the contribution of the stria vascularis remains unclear. In the present study, we demonstrate that gentamicin administration induces apoptosis of stria vascularis pericytes, leading to stria vascularis dysfunction and consequent hearing loss in mice. Mechanistically, gentamicin exposure activated macrophages within the stria vascularis and significantly increased local expression of tumor necrosis factor-α (TNF-α). In vitro, we found that TNF-α triggered stria vascularis pericyte apoptosis via activation of the NF-κB signaling pathway. Importantly, in vivo pharmacological blockade of TNF-α with infliximab (IFX) or inhibition of NF-κB signaling with JSH-23 effectively preserved pericyte survival, attenuated stria vascularis damage, and mitigated gentamicin-induced hearing loss in mice. Collectively, these findings uncover TNF-α/NF-κB-dependent vascular-inflammatory mechanism underlying gentamicin ototoxicity and identify stria vascularis pericytes as a novel and druggable therapeutic target for the prevention of gentamicin-induced hearing loss.

Evolutionary shifts in diel activity patterns shape sensory remodeling across mammals, yet the genetic basis remains poorly understood. Tapirs represent a unique natural experiment, having reverted from a cathemeral ancestor to a nocturnal niche characterized by reduced vision but enhanced hearing and olfaction. Here, we investigate the genetic basis of this phenomenon by generating high-quality chromosome-level genomes for Tapirus terrestris and Tapirus indicus . Comparative analyses revealed extensive lineage-specific remodeling of genes and cis-regulatory elements linked to sensory pathways. Notably, functional validation via CRISPR-Cas9 editing of a tapir-specific conserved noncoding element (CNE74) upstream of the FLT1 gene in mice revealed coordinated sensory effects, including retinal degeneration and reduced visual acuity, yet enhanced auditory sensitivity. These findings suggest that regulatory element evolution may induce pleiotropic effects on competing sensory modalities, offering genetic insights into sensory evolution during temporal niche adaptation and potential relevance to human retinal vascular diseases.

In the mammalian cochlea upon acoustic stimulation, outer hair cells (OHCs) push and pull the basilar membrane, amplifying its vibration and therefore expanding the dynamic range of hearing. As a result, spiking patterns in auditory nerve fibers (ANFs) are believed to be significantly different, but how the central nervous system adapts to this substantial change is poorly understood. In this study, we took advantage of Prestin −/− mice of either sex where prestin, the motor protein in OHCs, was genetically knocked out, therefore removing cochlear amplification completely without changing the cellular structure of the cochlea significantly. While exocytosis from inner hair cells in the cochlea was largely intact, transmission at the endbulb of Held synapse between ANFs and bushy cells in the cochlear nucleus was significantly changed in Prestin −/− mice. Specifically, excitability of bushy cells was significantly increased, due to combination of slightly more depolarized resting membrane potential, increased membrane input resistance, and smaller and briefer afterhyperpolarization. Furthermore, synaptic strength was greatly reduced, caused by substantial decrease in the readily releasable pool (RRP) of synaptic vesicles. Significantly, paired-pulse plasticity at this synapse was reversed from depression in WT mice to facilitation in Prestin −/− mice, likely caused by quicker refilling of RRP observed in Prestin −/− mice. In conclusion, we found that transmission at the endbulb of Held synapse is significantly altered in absence of cochlear amplification, revealing interplay between the peripheral and central processing of auditory signals that contributes to expanded dynamic range of hearing seen in mammals and humans.

Cisplatin‐induced ototoxicity is a detrimental side effect of chemotherapy leading to hearing loss, for which no treatments are currently available. Despite the growing recognition of the endocannabinoid (eCB) system (ECS) as a significant contributor to different physiological and pathological processes, its role in hearing remains poorly investigated. To fill this knowledge gap, we performed a molecular profiling of the ECS in auditory hair cell (HC)‐like UB/OC1 cells derived from the mouse organ of Corti (OC), demonstrating the presence of the main eCBs‐binding receptors and metabolic enzymes along with the major eCBs ( N ‐arachidonoylethanolamine, AEA, and 2‐arachidonoylglycerol, 2‐AG) and additional eCB‐like compounds. Subsequently, we established an in vitro model of cisplatin‐induced ototoxicity, which was characterized by the downregulation of the HC marker myosin 7a (Myo 7a), and activation of nuclear factor kappa‐light‐chain‐enhancer of activated B‐cells (NF‐κB) associated with caspase‐3‐mediated cell death. In this model, we observed a downregulation of cannabinoid receptor 2 (CB 2 R), diacylglycerol lipase β (DAGLβ), and α/β hydrolase domain‐containing protein 6 (ABHD6), indicating a perturbation of the 2‐AG metabolic pathway. Furthermore, we validated the observed in vitro alterations in the OC of an in vivo model of cisplatin‐induced ototoxicity, thereby strengthening the physiological relevance of our findings. Finally, we demonstrated that pharmacological blockade of CB 2 R through SR144528 mitigates cisplatin‐induced HC damage via inhibition of caspase‐3 cleavage in UB/OC1 HC‐like cells, thereby providing novel mechanistic insights into the role of CB 2 R in ototoxicity. Overall, our study demonstrates the involvement of selective elements of the ECS in cisplatin‐induced ototoxicity, hence identifying novel potential biomolecular targets for chemotherapy‐related side effects.

Shaker‐1 mice carry a spontaneous missense mutation in Myo7a ( Myo7a Sh1 ) that interferes with the motor function of MYO7A. Mutation in the orthologous gene in humans causes syndromic (Usher 1B) or non‐syndromic forms of deafness. In hair cells, MYO7A is expressed throughout the stereocilia, where it has been implicated in tip‐link tensioning required for gating the mechanoelectrical transducer (MET) channel and setting its resting open probability ( P o ). The Myo7a Sh1 mutation progressively dysregulated the height of shorter stereocilia rows from the end of the first postnatal week onwards, associated with reduced MET current amplitude and hearing loss. Noise exposure exacerbated stereocilia dysfunction in Myo7a Sh1/Sh1 mice. Following the onset of maturation, hair cells from Myo7a Sh1/Sh1 mice showed normal resting P o and calcium sensitivity of the MET channel. In immature Myo7a Sh1/Sh1 hair cells, the resting P o was very small or absent in comparison to control cells, but it was restored by changing the membrane lipid bilayer fluidity or thickness by depleting cholesterol or PIP 2 . Bundle stiffness in immature IHCs was not affected by the absence of functional MYO7A but decreased after their onset of maturation in both genotypes. Expression of a subset of genes was affected similarly in immature Myo7a Sh1/Sh1 mice and in adult Myo7a conditional knockout mice, indicating a common response pathway in Myo7a ‐deficient mice. This study reveals that MET channel gating might differ depending on hair cell developmental stage, and MYO7A is likely to influence, albeit indirectly, force transmission via the lipid bilayer to the MET channel and maintenance of the shorter rows of transducing stereocilia. image Key points Shaker‐1 mice carry a spontaneous missense mutation in the shaker‐1 gene ( Myo7a Sh1 ) that interferes with the motor function of MYO7A, a protein expressed in hair‐cell stereocilia. The absence of functional MYO7A ( Myo7a Sh1/Sh1 mice) caused a progressive dysregulation in the height of the shortest two rows of stereocilia and the consequent loss of mechanoelectrical transduction (MET) current. Although immature hair cells from Myo7a Sh1/Sh1 mice exhibited a markedly reduced resting open probability of their MET channels, this was restored upon maturation or following depletion of cholesterol or PIP 2 from the lipid bilayer. Hair‐bundle stiffness was affected in immature inner hair cells from Myo7a Sh1/Sh1 mice, suggesting that MYO7A is not required for establishing the resting tension of the tip links gating the MET channels. We conclude that MYO7A is crucial for the structural integrity of the MET complex and transport of key proteins required to transfer forces efficiently from the lipid bilayer to the MET channel.

Atypical sensory processing is a common feature of autism, yet the neural computations that give rise to these differences, particularly in relation to biological sex and etiological origin, remain unclear. Here we examine predictive auditory processing at the single-neuron level in the inferior colliculus of two adult rat models of autism: a genetic model with a heterozygous Grin2b deletion (Grin2b + /-) and an environmental model based on prenatal valproic acid exposure. We recorded neuronal responses to an auditory oddball paradigm and a cascade control sequence across lemniscal and non-lemniscal IC divisions under high-intensity stimulation, allowing us to derive indices of repetition suppression, prediction error and neuronal mismatch. Using generalized linear mixed-effects models that accounted for animal identity, inferior colliculus division, sex, and rat model, followed by hierarchical group-level comparisons, we identified robust alterations in predictive processing in both autism-like models. These effects varied across inferior colliculus divisions and differed between sexes, revealing distinct phenotype-specific signatures. The results indicate that sex and etiology jointly modulate early auditory computations in autism. More broadly, our findings highlight the translational value of predictive coding frameworks and support the use of complementary animal models to capture neurobiological heterogeneity across the autism spectrum.

NF2 (neurofibromatosis type 2)–related schwannomatosis (NF2-SWN) is a cancer predisposition syndrome characterized by the development of bilateral vestibular (VS) and spinal schwannomas. While benign, these tumors can cause substantial morbidity, and effective pharmacological treatments remain limited. Here, we demonstrate that genetic ablation of focal adhesion kinase ( Fak/Ptk2 ) impairs tumor formation and preserves hearing in a murine model of NF2. Mechanistically, we show that Fak deletion decreases macrophage infiltration, attenuates nucleotide-binding oligomerization domain–containing protein 2–, leucine rich repeats (LRR)- and pyrin domain–containing protein 3 inflammasome activation, and suppresses the hepatocyte growth factor–MET axis. Pharmacological inhibition of FAK with single agent VS-4718 did not significantly reduce macroscopic tumor volume; however, its use in combination with the mitogen-activated protein kinase kinase (MEK) inhibitor selumetinib resulted in both a significant reduction in tumor volume and the preservation of dorsal root ganglion architecture. Our findings establish a critical role for FAK in schwannoma development and provide rationale for evaluation of combination FAK plus MEK inhibition in future clinical trials for NF2-associated SWN.

Background: Otitis media (OM) is an inflammatory disease of the middle ear characterized by mucosal remodeling, effusion, and conductive hearing loss. Although antibiotics and surgical procedures remain standard treatments, their efficacy is often limited by recurrence, antibiotic resistance, and chronic progression. Transcutaneous auricular vagus nerve stimulation (taVNS) is a non-invasive neuromodulatory technique that activates the cholinergic anti-inflammatory pathway through α7 nicotinic acetylcholine receptor (α7nAChR) signaling. This study aimed to evaluate the anti-inflammatory effects of taVNS in a lipopolysaccharide (LPS)-induced mouse model of acute otitis media (AOM) and to assess whether these effects may involve α7nAChR-dependent mechanisms. Methods: AOM was induced by transtympanic injection of LPS in BALB/c mice, followed by taVNS applied to the auricular concha using biphasic square pulses (0.3 mA, 20 Hz, 200 μs). Methyllycaconitine, a selective α7nAChR antagonist, was administered to assess receptor involvement. Auditory function, tympanic membrane morphology, and mucosal changes were assessed through auditory brainstem response testing, otoscopic imaging, and histological analysis. Cytokine levels in middle ear effusion and serum were quantified by ELISA, while inflammatory gene and protein expression were analyzed using qPCR and Western blotting. Statistical analyses were performed using one-way ANOVA or Kruskal-Wallis tests with post hoc comparisons. Results: taVNS significantly improved hearing thresholds and reduced mucosal thickening and goblet cell hyperplasia in AOM mice. It markedly decreased tumor necrosis factor-α, interleukin (IL)-1β, and IL-6 levels in middle ear effusion, and mechanistically, this anti-inflammatory effect was associated with suppression of NF-κB activation without altering TLR4 or MYD88 expression. These effects were abolished by methyllycaconitine pretreatment. taVNS also reduced spleen enlargement and systemic cytokine concentrations, indicating modulation of both local and systemic inflammation. Conclusions: taVNS was associated with attenuation of LPS-induced acute otitis media and reduced NF-κB activation and downstream cytokine expression in a manner consistent with the involvement of α7nAChR-related signaling. By attenuating excessive inflammatory responses, taVNS was associated with improved auditory function and reduced middle ear injury, suggesting its potential as a non-invasive therapeutic strategy for LPS-induced acute otitis media.

Proper orientation of the apical cytoskeleton in auditory and vestibular hair cells is essential for their sensory function. A recently identified regulator of hair cell orientation is the G protein-coupled receptor GPR156, which signals through inhibitory heterotrimeric G proteins. In hair cells expressing the transcription factor EMX2, GPR156 is apically enriched and polarized at cell junctions. There, GPR156 signaling reverses the interpretation of tissue-level core planar cell polarity cues, effectively reversing the orientation of Emx2 -positive compared to Emx2 -negative hair cells. This mechanism establishes key anatomical features, such as the correct alignment of auditory outer hair cells and the line of polarity reversal in the otolith organs of the vestibular system. Null mice with constitutive Gpr156 inactivation exhibit severe hearing loss, mirroring congenital hearing impairment in human patients with homozygous GPR156 variants. These null mutants also display impaired swimming and vestibulo-ocular reflexes, although the nature of these vestibular deficits differs from those reported in Emx2 mutants. Here, to determine the extent to which functional deficits arise from hair cell misorientation, we conditionally inactivated Gpr156 in postmitotic hair cells in the inner ear. This targeted deletion approach recapitulated the misorientation phenotype observed in null mutants. Notably, 30–40% of cochlear and utricular hair cells affected in the null background retained normal orientation in conditional mutants, likely due to the later timing of Gpr156 inactivation. Despite reduced efficiency, conditional mutants exhibited similar, albeit predictably milder, auditory and vestibular dysfunction. As hair cells can carry out mechano-electrical transduction without GPR156, we conclude that sensory deficits mainly result from its essential role in hair cell orientation.

Gap junction Beta 2 Protein (GJB2, Connexin26, Cx26), the primary genetic cause of hereditary hearing loss (25%–50% of cases), has been exclusively regarded as forming an intercellular channel that mediates rapid communication. Here, we redefine its biological role by discovering its nuclear localization and direct transcriptional regulatory function in cochlear structure development. We demonstrate that Cx26 could aggregate in the nucleus of cochlear support cell and cell lines. Cx26 can bind to the promoter transcription start point of genomic DNA and directly regulate gene transcription, thus controlling the structural development of the tunnel of Corti during cochlear development. Further, we provide strategies based on mechanisms to promote the TC development and hearing rescue in Cx26 deficient cochlea, which has important implications for the discovery and development of treatment strategies for hearing loss caused by Cx26 deficiency.

Cisplatin-based chemotherapy causes hearing loss in 40-60 % of all patients, yet effective preventative options remain limited. Building on prior animal studies, we demonstrate that oral administration of AZD5438, a potent and selective CDK2 inhibitor, provides dose-dependent protection against hearing loss in a clinically relevant multi-dose cisplatin mouse model. Protective doses (4.7 and 9.4 mg/kg b.i.d.) fall within the human-equivalent maximum tolerated dose range established in AstraZeneca trials, and exhibit plasma pharmacokinetics comparable to those in humans. Importantly, AZD5438 at 9.4 mg/kg b.i.d. does not reduce cisplatin's anti-tumor efficacy in a testicular cancer xenograft model, consistent with in vitro findings. These results support AZD5438 as a promising candidate for clinical trials to prevent cisplatin-induced hearing loss while preserving cancer treatment efficacy.

Hearing loss is the most common sensory organ disorder, with genetic factors contributing substantially to the disease. Among the 87 genes responsible for autosomal recessive nonsyndromic hearing loss, mutations in MPZL2 have been frequently linked to mild-to-moderate autosomal recessive hearing loss (DFNB111). Here, we present multiple families whose hearing loss arose from biallelic mutations in the MPZL2 gene and found that the MPZL2 p.Q74∗ mutation may be a founder allele among East Asians. Furthermore, we generated an Mpzl2 p.Q74∗ knockin mouse model that exhibited autosomal recessive, progressive, ski-sloping hearing loss with Deiter's cell degeneration. Gene supplementation using AAV-DJ or AAV-PHP.eB to deliver human MPZL2 (hMPZL2) under control of the CAG promoter induced ototoxicity, whereas employing an alternative EF1α promoter with AAV-DJ (DJ-EF1α-hMPZL2) circumvented this issue, restoring long-term auditory function and Deiter's cell survival in Mpzl2Q74∗/Q74∗ mice for up to 24 weeks. Overall, this study provides the foundational steps for developing a safe and effective biological treatment for DFNB111 and underscores the importance of precise regulation of target cells and transgene expression in AAV-based treatments.

Objective: The purpose of this paper is to present a chronic, preclinical, pilot study of a multi-electrode auditory nerve implant. To date, the most successful auditory neuroprosthesis is the cochlear implant, but these devices have known limitations. Intraneural stimulation of the auditory nerve is a promising alternative, but preclinical investigations of multi-electrode devices have been limited to acute or semi-chronic studies. Methods: Six cats were chronically implanted in the right auditory nerve with a 15-channel Utah Slant ArrayTM. The array's position in the internal auditory canal was confirmed using computed tomography. Electrode impedance and evoked responses were recorded regularly during the indwelling period to evaluate performance. Results: Two of the six implants met endpoint criteria at 6 months, with stable electrode impedances and robust evoked responses on at least 50% of their channels. Another two implants exhibited stable electrode impedances, but activation thresholds increased over three months. Two implants failed within the first two weeks due to device migration caused by connector-related issues. Conclusion: This study reports the first successful chronic deployment of an multi-electrode auditory nerve implant in a preclinical model. Two implanted cats exhibited stable chronic performance, marked by a consistent set of electrodes capable of eliciting evoked responses. The failure modes of the remaining four cats are discussed and recommendations are made to stabilize implant placement. The study lays a solid foundation for future chronic safety and efficacy investigations as part of an effort to translate this new neuroprosthetic technology into the clinic.

Introduction: Hearing is critical for communication and clinical evidence suggests that hearing loss can lead to poorer mental well-being including social isolation, anxiety, depression, and cognitive decline. Deaf animal models offer opportunities to investigate the impact of hearing loss on behavioral correlates of mental health while controlling for genetic variability and shared etiological factors such as environmental stressors, aging, and metabolic diseases. We previously showed that conditional deletion of Ebf1 in the inner ear causes deafness. We hypothesize that otic-specific Ebf1 knockout (KO) mice recapitulate neurobehavioral alterations experienced in congenital deafness. Methods: Slc26a9P2A-Cre and Ebf1 floxed mice were crossed previously to generate the otic-specific Ebf1 conditional KO. We measured auditory brainstem response and behavior in groups of otic-specific Ebf1 conditional KO mice and Cre-negative littermate controls (WT). We performed behavioral tests including elevated plus maze, acoustic startle, locomotor activity, forced swim, and Y-maze. Results: We found that the KO mice spend significantly less time than WT mice in the open arms of the elevated plus maze. KO mice also show significantly increased latency to enter the open arms. Acoustic startle response was decreased in KO mice vs. WT controls and pre-pulse inhibition was also reduced in the KO, consistent with elevated hearing thresholds. We found no significant differences in exploratory behavior, forced swim immobility time, or other behavioral measures examined. Conclusions: Our findings demonstrate that deaf otic-specific KO mice are indeed a model for the study of effects of hearing loss on clinically relevant behavioral correlates. Our results provide new empirical evidence that hearing loss contributes to anxiety, which is consistent with clinical evidence that anxiety is associated with hearing loss in older adults.