Publications using TDT

Noise-induced hearing loss (NIHL) is a primary contributor to tinnitus, involving mechanisms such as inflammatory damage, central sensitization, and auditory cortex remodeling. However, not all cases of tinnitus are accompanied by NIHL, and the precise relationship between the two remains incompletely understood. Phosphorylation/dephosphorylation, as a core mechanism for fine cellular regulation, influences neuronal excitability, immune responses, and disease development by modulating protein activity, signal transduction, and gene expression. We hypothesized that aberrant phosphorylation levels may alter auditory cortex neuron function, leading to pathological changes at the protein level. Leveraging auditory cortex tissue from a noise-induced tinnitus model, we systematically investigated the pathogenesis of tinnitus and its distinction from NIHL through integrated proteomic and phosphoproteomic analyses. Compared to animals with NIHL alone, the tinnitus model exhibited enhanced neuronal excitability, synaptic dysfunction, hyperactive energy metabolism, and weakened neuroprotection, with disordered membrane receptor function playing a critical role. Multi-omics analysis further revealed that tinnitus development primarily depends on phosphorylation-mediated post-translational modifications reshaping cellular function, rather than changes in protein abundance caused by alterations in gene transcription levels. Collectively, this study elucidates the physiological and cellular structural alterations in noise-induced tinnitus from the dimensions of protein expression and phosphorylation modification. It confirms that tinnitus leads to neural dysfunction through abnormal membrane receptor activity, and the characteristic proteins and phosphorylation sites identified offer novel therapeutic targets for modulating central hyperexcitability in tinnitus.

Ionogels are promising for soft robotics, energy systems, and bioelectronic interfaces due to their high ionic conductivity and environmental stability. However, combining high strength and fracture resistance remains challenging. Here, we report composite ionogels with outstanding mechanical strength (~65.4 megapascal) and fracture energy (~607 kilojoules per square meter), capable of bearing more than 5000 times their own weight. These ionogels are developed by tailoring solvent-solute interactions to create a dense, hyperconnected nanofibrous polymer network. Solvent engineering regulates hydrogen bonding competition, facilitating the formation of robust interphase hydrogen bonds and a soft-hard biomimetic interface. Moreover, their antidrying, breathable nature enables multifunctional electrophysiological monitoring, making them ideal for wearable bioelectronics. Their ionic conductivity, drug-loading capacity, and antibacterial properties allow their use in advanced e-bandages for chronic wound healing. This generalizable strategy for ionogel design opens pathways toward strong, versatile, and biocompatible materials, particularly valuable for next-generation soft materials, wearable electronics, and tissue engineering.

Persistent maladaptive drug-context associations are a key component of relapse vulnerability and pose a major obstacle in treating opioid use disorder. Although the dorsal hippocampus (dHPC) is critical for contextual memory formation, the synaptic mechanisms by which opioids alter hippocampal circuits to sustain these associations remain unclear. We previously found that repeated context-paired morphine exposure impairs dHPC long-term potentiation (LTP) through enhanced activity of small-conductance calcium-activated potassium (SK2) channels. Here, we investigated the role of SK2 channels in morphine-context associative learning and memory by combining in vivo electrophysiology, molecular analyses, and behavioral pharmacology with the morphine-conditioned place preference (MorCPP) paradigm in male mice. Manipulation of SK2 channels with either SK2 blocker Lei-Dab7 or activator NS309 before MorCPP post-test dose-dependently reduced MorCPP preference, despite no changes observed in SK2 mRNA or protein expression following MorCPP post-test. Interestingly, SK2 blockade during conditioning instead facilitated morphine-context memory formation, suggesting a distinct SK2 role in drug-context memory acquisition versus retrieval. Electrophysiology data suggest that modulation of dHPC neuronal activity by SK2 channels could be a potential mechanism underlying these observations. Our findings demonstrate that dHPC SK2 channels regulate morphine-context memory formation and retrieval, identifying them as a candidate for mitigating context-driven drug behaviors.

The thalamocortical pathways exhibit neuroplasticity not only during the critical period but also in adulthood. In this study, we investigated how cholecystokinin (CCK) modulates age-dependent thalamocortical plasticity. Our findings demonstrated that CCK is expressed in thalamocortical neurons and that high-frequency stimulation (HFS) of the thalamocortical pathway triggers the release of CCK in auditory cortex (ACx), as detected by a CCK sensor. HFS of the medial geniculate body (MGB) induced thalamocortical long-term potentiation (LTP) in wild-type young adult mice. However, knockdown of CCK expression in MGB neurons or blockade of the CCK-B receptor (CCKBR) in the ACx abolished HFS-induced LTP. Interestingly, this LTP could not be elicited in juvenile (3-week-old) or aged mice (over 18-month-old) due to distinct mechanisms: the absence of CCKBR in juveniles and the inability to release CCK in aged mice. Notably, exogenous administration of CCK into the ACx rescued LTP in aged mice and significantly improved frequency discrimination. These findings highlight the potential of CCK as a therapeutic intervention for ameliorating neuroplasticity deficits associated with thalamocortical connectivity.

Acquired sensorineural hearing loss (SNHL) is primarily caused by the damage or loss of hair cells (HCs), induced by factors such as noise exposure and ototoxic drugs. However, clinical treatments for SNHL remain limited. Here, the role of the apoptosis‐inducing gene Cidea in SNHL is investigated. It is initially observed that Cidea expression is specifically increased in neomycin‐damaged HCs at both the protein and mRNA levels. To further explore its role, Cidea knockout (Cidea‐/‐) mice are obtained, and it is found that the absence of Cidea effectively alleviates HC apoptosis caused by neomycin treatment and noise exposure in vivo. Moreover, a novel therapeutic strategy for SNHL has been developed by delivering CRISPR/SlugCas9‐HF via AAV to edit Cidea , and this approach significantly reduced HC loss induced by both neomycin and noise exposure. These findings suggest that Cidea may serve as a promising target for the prevention of neomycin‐ and noise‐induced SNHL in clinical settings.

Dopamine release in the nucleus accumbens is classically linked to associative learning, signaling relationships between predictive cues and outcomes. Yet, dopamine is also strongly modulated by novelty, a nonassociative factor that has received comparatively little attention. Here, we used optical dopamine sensors in awake, behaving male and female mice to define how novelty alters the temporal dynamics of dopamine release during aversive learning. We manipulated novelty in three ways: (1) omitting expected footshocks, (2) introducing novel neutral cues concurrently with shock-predictive stimuli, and (3) presenting novel stimuli in an unpaired fashion within a context. Across all conditions, manipulations robustly increased dopamine release and in some cases altered the directionality of cue-evoked dopamine responses. Notably, these effects extended beyond the immediate stimulus window, altering subsequent responses to both conditioned cues and footshocks. Together, these findings demonstrate that changes in the environment that extend beyond prediction-based learning can exert a powerful and sustained influence on dopamine signaling, reshaping how aversive cues and outcomes are represented in the brain.

Background Bmi1, a key component of the Polycomb repressive complex 1, plays a critical role in regulating gene expression by modulating chromatin structure. Its depletion is known to cause hair cell loss in the neonatal mouse cochlea. This study aimed to investigate the epigenetic mechanisms and transcriptional consequences of Bmi1 depletion in the neonatal auditory sensory epithelium. Results Analysis of neonatal Bmi1 knockout mice using H3K27me3 chromatin immunoprecipitation sequencing, assay for transposase-accessible chromatin sequencing, and RNA sequencing revealed significant transcriptional alterations, particularly in genes governing cell proliferation, senescence, and death. Bmi1 depletion resulted in widespread gene upregulation and increased chromatin accessibility, which correlated with reduced H3K27me3 enrichment. Notably, expression of Cdkn2c , a key cell cycle regulator, was significantly upregulated. Inhibition of Cdkn2c rescued the proliferative capacity of inner ear epithelial cells in Bmi1 knockout mice. Conclusions These findings demonstrate that Bmi1 maintains transcriptional repression and chromatin state in the developing cochlea, primarily through H3K27me3 deposition. Depletion disrupts this control, leading to Cdkn2c overexpression and impaired cell proliferation. This identifies Cdkn2c and its regulatory pathway as potential therapeutic targets for hearing loss associated with hair cell depletion.

During wake, sound‐evoked and spontaneous neural activity of the auditory cortex evolves in distinct subspaces, whereas anesthesia disrupts sound responses and merges these spaces. To evaluate if similar modifications of sound representation geometry explain sensory disconnection during sleep, large neural populations of the mouse auditory cortex are followed across slow‐wave sleep and wakefulness. It is observed that sleep dampens sound responses but preserves the geometry of sound representations such that they remain separate from spontaneous activity. Moreover, response dampening is strongly coordinated across neurons and varied throughout sleep, spanning from fully preserved response patterns to population response failures on a fraction of sound presentations. These failures rarely occurred in wakefulness and are more common during high spindle‐band activity. Therefore, in sleep, the auditory system preserves sound feature selectivity up to the cortex for detailed acoustic surveillance but concurrently implements an intermittent gating mechanism leading to local sensory disconnections.

Anxiety disorders impose a substantial global burden, yet current pharmacotherapies often lack sustained efficacy and carry risks of dependence. Dexmedetomidine (Dex), a selective α2 adrenergic receptor agonist primarily used for sedation, demonstrates promising anxiolytic properties, but its long-term neural mechanisms remain unclear. Here, using a chronic restraint stress (CRS) mouse model, we reveal that tyrosine hydroxylase (TH)-positive neurons in the locus coeruleus (LC) are persistently hyperactivated during chronic anxiety states, driving elevated norepinephrine (NE) release in the medial prefrontal cortex (mPFC). A single low dose of Dex (50 µg/kg) produced anxiolytic effects lasting ≥3 days, evidenced by improved performance in open-field, light-dark box, and elevated plus maze tests. In vivo fiber photometry and chemogenetic approaches demonstrated that Dex suppresses LC-NE neuronal hyperactivity and normalizes mPFC NE levels. Crucially, neuron-specific knockdown of α2 receptors in the LC abolished Dex's anxiolytic effects, confirming their essential role. These findings elucidate a neural mechanism wherein Dex sustains anxiety relief via α2 receptor-mediated inhibition of the LC-NE-mPFC circuit, highlighting its potential as a novel long-acting therapeutic strategy for anxiety disorders.

Normally hearing humans can localize sound sources quite accurately, with minimum audible angles as small as 1°. To achieve this, these auditory pathways combine information from multiple acoustic cues, including interaural time and interaural level differences (ITDs and ILDs). Patients relying on cochlear implants (CIs) to hear the world do not match normal performance. These deficits are most pronounced in patients with little or no hearing experience early in life, and they appear to result from impaired sensitivity to ITDs, but not to ILDs. However, little is known about how ITD and ILD sensitivities develop and interact in an early deafened auditory system shortly after CI implantation. Neonatally deafened rats were fitted with bilateral CIs, and, providing informative ITDs and ILDs from stimulation onset, were trained to lateralize CI stimuli. These animals are exquisitely sensitive to both ILDs and ITDs of CI stimulus pulses, and combined information from both cues in a weighted sum. Importantly, ITDs are weighted heavily in the CI rats, such that only very modest ITDs pointing in one direction can confound quite large ILDs pointing in the opposite direction. This underlines the importance of informative ITDs for maximizing the potential for spatial hearing with CI devices.

As part of a deep brain stimulation (DBS) procedure, direct electrophysiological recordings from thalamic and basal ganglia circuits were obtained from a pediatric participant with secondary dystonia to examine the neural mechanisms of motor timing. The participant performed a two-phase repetitive timing task that began with synchronization to a series of externally presented auditory cues, followed by a continuation phase in which the participant maintained the movement rhythm without external guidance. Simultaneous recordings from stereoelectroencephalography (sEEG) leads implanted in the globus pallidus internus (GPi), subthalamic nucleus (STN), ventral oralis (Vo), centromedian nucleus (CM), and thalamic nuclei receiving projections from the cerebellum (ventral intermediate nucleus (VIM) and centrolateral nucleus (CL)) revealed behaviorally relevant neural dynamics. Local field potentials (LFPs) from recorded nuclei exhibited strong, time-locked responses during the synchronization phase, with reduced amplitudes during the continuation phase. Time-frequency analysis showed consistent power increases around the corresponding mean of the inter-response intervals (IRIs) in both behavioral output and neural signals, suggesting frequency-specific entrainment across circuits. These findings suggest of cerebellar-thalamic and basal ganglia contributions to temporal coordination.

Neural circuits undergo experience-dependent plasticity to form long-lasting memories, but how inhibitory interneurons contribute to this process remains poorly understood. Using miniature microscope calcium imaging, we monitored the activity of large amygdala interneuron populations in freely moving mice during fear learning and extinction. Here we show that interneurons exhibit complex and heterogeneous plasticity at both single-cell and ensemble levels across memory acquisition, expression, and extinction. Analysis of molecular interneuron subpopulations revealed that disinhibitory vasoactive intestinal peptide (VIP)-expressing cells are predominantly activated by salient external stimuli, whereas the activity of projection neuron targeting somatostatin (SST) interneurons additionally aligns with internal behavioural states. Although responses within each interneuron subtype are non-uniform, molecular identity biases their functional role, producing weighted circuit outputs that can flexibly regulate excitatory projection neuron activity and plasticity. These findings demonstrate that inhibitory interneurons actively shape the encoding and stability of emotional memories, underscoring their importance in adaptive learning.

Heavy metal ion exposure has become a global public health concern. Among them, lead is an extremely toxic heavy metal that poses serious health hazards to humans, particularly threatening vulnerable groups such as children and the elderly. Currently, the effects of chronic low‐dose lead exposure on the auditory system have yet to be reported. In this study, we established a chronic lead exposure mouse model and conducted comprehensive auditory function assessments. The results demonstrated that lead‐exposed mice developed high‐frequency hearing loss at early stages, which progressively worsened over time. Morphological examination of the inner ear revealed hair cell loss, reduced synaptic ribbon numbers, and disruption of gap junctions in lead‐exposed mice. Furthermore, immunofluorescence staining confirmed significantly decreased expression of the mitochondrial protease LONP1, along with markedly increased expression of its substrate HMGCS2, in the stria vascularis, sensory epithelium, and spiral ganglia of lead‐exposed mice. These findings indicate that chronic low‐level lead exposure causes inner ear damage and irreversible auditory dysfunction, while accelerating age‐related hearing loss in C57BL/6J mice. These preclinical results suggest that chronic lead exposure may represent a significant risk factor for age‐related hearing loss, deepen our understanding of lead‐induced auditory system impairment, and hold profound implications for preventing hearing damage in populations at high risk of lead exposure.

Background CLN3 disease, also known as juvenile Batten disease, is a recessively inherited neurodevelopmental disorder caused by mutations in the CLN3 gene. It represents the most common form of Neuronal Ceroid Lipofuscinoses (NCLs), a group of lysosomal storage disorders that impair brain function. Clinical features include progressive vision loss, language impairment, and cognitive decline. The early onset of visual deficits complicates the neurological assessment of cognitive dysfunction, while the rarity of CLN3 cases limits the study of sex-specific disease trajectories in humans. Therefore, there is a critical need for objective, translational biomarkers to monitor disease progression and support therapeutic development in preclinical animal models. Methods Building on our recent studies in individuals with CLN3 disease, we developed a parallel experimental paradigm using high-density electroencephalography (EEG) in Cln3 knockout ( Cln3-/-) mice to longitudinally assess auditory neurophysiological changes. We applied a duration-based mismatch negativity (MMN) paradigm, similar to that used in our human studies, to evaluate automatic detection of auditory pattern changes in male and female mice between 3 and 9 months of age. Results Wild-type (WT) mice of both sexes showed robust and stable duration MMN responses across this age range. In contrast, Cln3-/- mice showed marked sex- and age-dependent deficits: female mutants displayed persistent MMN deficits, whereas male mutants exhibited early MMN abnormalities that unexpectedly improved with age. Auditory brainstem responses confirmed intact peripheral hearing in Cln3-/- mice, indicating a central origin for the observed abnormalities. Further analyses revealed that MMN impairments were driven by age- and sex-specific alterations in auditory evoked potentials to both standard and deviant stimuli. Conclusions These findings demonstrate sex- and age-dependent disruptions in central auditory processing in Cln3-/- mice and support auditory duration MMN as a sensitive, translational biomarker of brain dysfunction in CLN3 disease. This approach offers a functional, cross-species measure for tracking disease progression and evaluating therapeutic interventions in Batten disease.

Sensory issues are common in autism spectrum disorders (ASD) and can significantly affect daily living. The phenomena of gating and habituation of event-related potentials (ERPs) to repetitive stimuli have been suggested as potential biomarkers reflecting atypical sensory processing in ASD. Sensory hypersensitivity and anxiety are closely related in ASD, and habituation to emotionally evocative stimuli may serve as a more sensitive biomarker for sensory hypersensitivity symptoms. However, previous studies have primarily used tonal stimuli, and there has been little investigation into whether habituation to emotionally evocative sounds is impaired in ASD patients. In this study, we compared the degree of habituation of the P1-N1 peak-to-peak amplitude in response to repeated tones and fearful vocalizations between control and ASD groups. Contrary to expectations, no significant difference was observed for fearful vocalizations between the groups, while ASD patients showed significantly reduced habituation to tonal sounds in the left parieto-occipital region. Furthermore, we found a significant correlation between the degree of habituation to tonal sounds in the left parieto-occipital region and sensory hypersensitivity symptoms in ASD patients, and similar abnormalities in BTBR mice, an animal model of ASD. These results suggest that habituation to tonal sounds, rather than emotionally evocative stimuli, may serve as a translational biomarker reflecting sensory hypersensitivity symptoms.

Noise-induced hearing loss (NIHL) involves a biphasic pathophysiology. Intense noise exposure causes immediate cochlear vasoconstriction and ischemia, leading to transient hypoxia. Subsequent reperfusion triggers excess reactive oxygen species (ROS) production, resulting in oxidative stress and hair cell injury. This study therefore developed two oxygenated albumin microbubble (OMB) formulations-ionic-bond metformin-coated (iMet-OMBs) and covalent-bond metformin-encapsulated (cMet-OMBs)-and combined them with transcranial ultrasound (US) to enhance targeted delivery to the cochlea. This approach aims to provide transient oxygen supplementation while simultaneously reducing ROS-mediated injury. Microbubbles were characterized for morphology, oxygen loading, and metformin content. Based on their superior stability and drug-loading profile, cMet-OMBs were selected for in vivo evaluation. In a mouse NIHL model, animals were administered cMet-OMBs systemically via retro-orbital injection, followed by US triggering over the temporal bone. Auditory brainstem response (ABR) thresholds, cochlear oxygen tension, and outer hair cell (OHC) survival were assessed. US-mediated cMet-OMBs rupture transiently increased intracochlear oxygen tension, counteracting early hypoxia after noise exposure. Metformin released from cMet-OMBs attenuated ROS production through mitochondrial complex I inhibition and antioxidant pathway activation. Mice treated with cMet-OMBs + US showed significantly lower ABR threshold shifts and better OHC preservation compared with controls. This dual-action strategy combines transient oxygen supplementation from OMBs with sustained antioxidant protection from metformin. While oxygen delivery raises intracochlear oxygen tension, metformin suppresses ROS generation through mitochondrial complex I inhibition and AMPK/Nrf2 activation. This controlled, US-triggered release achieves net cochlear protection against NIHL without excessive oxidative burden.

Cisplatin (CDDP), a widely used chemotherapeutic agent, is limited by severe ototoxicity side effects. Local drug delivery via the middle ear represents the most effective approach for treating inner ear disease. However, therapeutic efficacy is constrained by poor middle ear retention and limited permeability across the round window membrane (RWM). Quercetin (QU) exhibits potent activity against CDDP-induced cytotoxicity but suffers from delivery challenges. To address this, we developed amino-functionalized mesoporous silica nanoparticles (NH2-MSNs) loaded with QU (QU-N-MSNs), leveraging the permselective properties of the RWM. This system was noninvasively administered to the cochlea via trans-tympanic delivery. The synthesized QU-N-MSNs demonstrated a uniform particle size of approximately 116–124 nm, positive charge, and sustained drug release properties. Compared to free QU, QU-N-MSNs demonstrated significantly enhanced antiapoptotic and cytoprotective activities in vitro. In vivo studies confirmed nanoparticle retention within the inner ear for ≥14 days post administration and efficient RWM penetration. Pretreatment with QU-N-MSNs prior to CDDP exposure in murine models substantially mitigated ototoxicity, as evidenced by reduced hearing threshold shifts across multiple frequencies, preservation of hair cells (HCs) and spiral ganglion neurons (SGNs), and attenuation of mitochondrial-mediated SGN apoptosis. These findings establish QU-N-MSNs as an effective RWM-penetrating delivery platform, offering a promising strategy to enhance hydrophobic drug bioavailability in the inner ear and prevent CDDP-induced ototoxicity.

A central mechanism of exposure-based cognitive behavioral therapy for anxiety and trauma-related disorders is fear extinction. However, the mechanisms underlying fear extinction are deficient in some individuals, leading to treatment resistance. Recent animal studies demonstrate that upon omission of the aversive, unconditioned stimulus (US) during fear extinction, dopamine (DA) neurons in the ventral tegmental area (VTA) produce a prediction error (PE)-like signal. However, whether this VTA-DA neuronal PE-like signal is altered in animals exhibiting deficient fear extinction has not been studied. Here, we used a mouse model of impaired fear extinction [129S1/SvImJ (S1) inbred mouse strain] to monitor and manipulate VTA-DA neurons during extinction. Male DAT-Cre mice backcrossed onto an S1 background (S1-DAT-Cre) exhibited impaired extinction but normal VTA-DA neuron number, as compared with BL6-DAT-Cre mice. In vivo fiber photometry showed that impaired extinction in male S1-DAT-Cre mice was associated with abnormally sustained US omission-related VTA-DA neuronal calcium activity during extinction training and retrieval. Neither in vivo optogenetic photoexcitation of VTA-DA neuronal cell bodies nor their axons in the infralimbic cortex was sufficient to rescue deficient extinction in male S1-DAT-Cre mice, at least within the optogenetic and behavioral parameters used. These data suggest that alterations in the activity of VTA-DA neurons during extinction learning and retrieval may be associated with deficient fear extinction in male S1 mice and could potentially contribute to extinction impairments in patient populations.

Bilateral cochlear implants (BiCIs) improve spatial-hearing outcomes relative to a single cochlear implant (CI), but the extent varies across patients. One limiting factor may be interaurally asymmetric spectro-temporal representations of sounds. The present study simulated interaural spectro-temporal asymmetries to explore how they affect binaural processing in listeners with normal hearing. We simulated CI stimulation using high-rate (500 pps) band limited acoustic pulse trains with a 3 mm bandwidth and 4 or 6.5 kHz center frequency. Second-order amplitude modulation (AM) was applied at a 100 Hz modulation rate, 20% or 50% modulation depth, and sinusoidal or sawtooth shape. Intracranial lateralization was used to assess utility of whole-waveform interaural time differences (ITDs). Results demonstrated that lateralization of envelope ITDs was limited by the ear with smaller AM depth. This effect depended upon the sharpness of temporal onsets and the extent to which frequencies overlapped in each ear. These results suggest that interaural asymmetry in spectro-temporal representations may limit binaural outcomes of patients with BiCIs. Two well-established models of binaural processing that assume interaural symmetry and rely on coincidence-detection were used to predict performance. Models were mostly predictive of performance, but made consistent errors, suggesting that models of BiCI stimulation using coincidence-detection should be improved to account for asymmetries.

Objective Transcranial current stimulation (tCS) is a promising technique to non-invasively modulate human brain activity. However, stimulation artifacts in EEG and MEG recordings severely hinder the study of its online effects. Approach Here, we introduce a new approach to account for these artifacts. The approach rests on two key ideas. First, we focus on interactions of tCS with intrinsic brain activity, which are absent for tCS artifacts. Second, rather than removing artifacts, we compare composite signals that share similar artifacts but potentially differ in the interaction of tCS with intrinsic brain activity. We follow a simple logic: if tCS does not interact with intrinsic brain activity, then neural activity during simultaneous sensory stimulation and tCS should equal the linear superposition of the neural effects of each applied alone. Any deviation from this prediction provides evidence for a neural interaction. Main results We tested this approach in a proof-of-principle MEG study, applying 10 Hz transcranial alternating current stimulation (tACS) during rest and during a 10 Hz visual flicker. We compared neural activity during simultaneous stimulation with that predicted by the linear superposition of flicker and tACS alone and found a phase-dependent interaction between tACS and flicker-evoked brain activity. Significance Our work establishes a novel approach to investigate online effects of tCS and suggests a state-dependent interaction of tACS with human brain activity.