Publications using TDT

Frontotemporal dementia (FTD) is a major cause of early-onset neurodegeneration characterized by progressive behavioral, emotional, and cognitive decline. Progranulin haploinsufficiency, a leading genetic cause of familial FTD, disrupts lysosomal function, lipid metabolism, autophagy, and neuroimmune signaling across multiple cell types. Increasing evidence indicates that microglia are particularly sensitive to progranulin loss, exhibiting elevated complement activation that contributes to TDP-43 proteinopathy and neuronal dysfunction. Here, we investigate the biological role of restoring progranulin exclusively within microglia by transplanting human induced pluripotent stem cell-derived microglia (iMG) into progranulin ( Grn )-deficient mice. We find that wild-type, but not Grn -deficient, human iMG restore brain-wide progranulin levels, normalize microglial transcriptional states, and ameliorate pathological, functional, and behavioral phenotypes associated with progranulin loss. Because microglia are the only source of progranulin in this system, these findings demonstrate that microglial progranulin is sufficient to restore key aspects of cellular, circuit, and behavioral homeostasis in a progranulin-deficient FTD model. More broadly, this work highlights a central, microglia-intrinsic role for progranulin in maintaining brain function and provides a framework for dissecting microglia-specific mechanisms across FTD and related neurodegenerative disorders.

Objective: Consequences of hearing abnormalities in migraine remain largely unexplored, particularly regarding peripheral outcomes. This study aims to explore how migraine induces peripheral auditory injury and what role calcitonin gene-related peptide (CGRP) plays in the inner ear, which may contribute to the precise subtyping of migraine and inform targeted auditory-protective therapies. Methods: A mouse model of chronic migraine (CM) was established by intermittent injections of nitroglycerin and validated via mechanical and thermal nociceptive assays. CGRP signaling was assessed by Western blotting and immunofluorescence. Auditory function was evaluated using auditory brainstem response (ABR) and distortion product otoacoustic emissions (DPOAE) in CM and CGRP blockade (Rimegepant-treated) groups. RNA sequencing of cochlear tissue identified dysregulated signaling pathways, which were subsequently validated in vitro using HEI-OC1 auditory cells and in vivo within the inner ear. Results: Repeated nitroglycerin injections induced persistent mechanical and thermal hyperalgesia, confirming successful model establishment. A significant upregulation of CGRP and its receptors, particularly in outer hair cells (OHCs) were confirmed. The CM mouse exhibited elevated ABR, DPOAE thresholds and OHC injury, all of which were mitigated by Rimegepant treatment. CGRP overstimulation triggered mitochondrial stress and mtDNA leakage in HEI-OC1 cells. Cytosolic mtDNA leakage activated the ZBP1-mediated PANoptosis pathway, leading to OHC injury. As proof of concept, ZBP1 knockdown and PANoptosis inhibition mitigated cellular damage and hearing deficits both in vivo and in vitro. Conclusions: We demonstrated OHCs as the key targets in CM-induced, CGRP-mediated peripheral hearing impairment. CGRP exerts its pathogenic role by triggering a cascade of intracellular stress and inflammatory pathways, ultimately leading to cell death. These findings provide a phenotypic basis for a subtype of migraine-induced hearing loss, paving the way for auditory protection strategies.

Theta oscillations - rhythmic patterns of synchronous activity within discrete brain regions - are known to support memory, navigation, and behavioral coordination, and are sensitive to pharmacological manipulation. Acute ethanol (EtOH) exposure has been shown to alter theta oscillations, but its effects on transient theta bursts and cross-regional coordination during naturalistic behavior remain unclear. We recorded local field potentials (LFPs) from the medial septum (MS), hippocampal Cornu Ammonis 1 (CA1), and medial prefrontal cortex (mPFC) in freely foraging mice following intraperitoneal injection of EtOH (1.5 g/kg) or saline. We analyzed spectral power, theta burst dynamics, phase, and lag timing. Burst features from CA1 were used to train a machine learning classifier to predict session condition. EtOH impaired locomotion and reduced goal-directed behaviors, particularly early in the session. In CA1, theta power shifted toward lower frequencies and lagged coherence declined. EtOH increased the frequency but reduced the duration of theta bursts in CA1, and in MS, only burst count increased. EtOH enhanced the temporal alignment of MS-CA1 burst pairs. Phase-locking between CA1 and MS during coupled bursts remained present but showed altered structure. Our classifier achieved robust performance using burst features such as skew and entropy, and reliably distinguished treatment conditions. EtOH modulates septohippocampal dynamics by altering the timing and structure of theta bursts. These results suggest that burst-level features are sensitive markers of EtOH's circuit-level effects during naturalistic behavior.

Objective. Intracortical microstimulation (ICMS) is a widely used tool for neuroprostheses, but its long-term efficacy is often limited by foreign body response and neuroinflammatory responses at the electrode-tissue interface. Microglia orchestrate neuroinflammation and regulate synaptic plasticity, and low-frequency stimulation has been shown to promote anti-inflammatory microglial phenotypes. Approach. We investigated how 10 Hz ICMS influences microglia–neuron interactions during the first three days post-implantation using in vivo two-photon imaging in Cx3cr1-GFP/jRGECO1a mice. Microglial motility, morphology, and process orientation were tracked relative to electrode placement and neuronal calcium activity (measured as change in fluorescence, Δ F / F ). Main results. A 1 h session of 10 Hz ICMS did not induce overt classical morphological activation of microglia but robustly increased process motility, with extensions dynamically tracking neurons showing early activation or subsequent functional suppression. By post-implantation Day 2, microglial processes were significantly more likely to engage neurons with high early calcium responses after stimulation onset (mean orientation angle: 74.3° ± 11.8°), but this engagement shifted during prolonged stimulation (117.0° ± 9.2°, p = 0.0017), indicating context-dependent interactions. Contact frequency scaled with neuronal adaptation profiles, and neurons exhibiting depressed activity received the most contacts immediately after implantation (1.2 ± 0.3 contacts, p = 0.046). Significance. These findings reveal stimulus-associated, neuron-dependent surveillance behaviors of microglia during early post-implantation ICMS and suggest that microglia actively participate in short-term modulation of stimulated cortical circuits.

Cytokines and their receptors play important roles in brain development and aging-related disease, but their functions within the healthy adult brain remain poorly understood. Here, we show that pyramidal neurons in hippocampal CA1 induce Fn14 expression in response to activity and environmental enrichment. Once expressed, Fn14 dampens the activity of these neurons most prominently at the daily transition between light and dark. Fn14 expression in CA1 neurons is regulated by the circadian transcription factor Bmal1, and mice lacking Fn14 exhibit disrupted sleep-wake patterns in vivo. At the cellular level, microglia contact fewer excitatory synapses in the absence of Fn14, while neuronal overexpression of Fn14 induces rod-like microglia and recruits them to excitatory synapses. Beyond a homeostatic context, mice lacking Fn14 exhibit heightened susceptibility to chemically induced seizures. These findings reveal that pro-inflammatory cytokine receptors such as Fn14 can play major roles in healthy neurological function in the adult brain.

Neurotransmitters and neuromodulators regulate brain states through diverse mechanisms, yet how their activities are coordinated during sleep remains unresolved. Using in vivo fiber photometry in adult mice expressing genetically encoded fluorescent biosensors, combined with EEG/EMG recordings, we investigated the temporal organization of multiple neuromodulators during sleep in barrel cortex, with norepinephrine (NE) as a reference signal. All five neuromodulators examined, acetylcholine, serotonin, dopamine, histamine, and NE, exhibited synchronized infraslow cortical oscillations during NREM sleep. Optogenetic suppression of locus coeruleus (LC) neurons abolished NE oscillations and selectively reduced acetylcholine fluctuations in barrel cortex, whereas targeted inhibition of basal forebrain cholinergic neurons attenuated REM-associated acetylcholine elevations without disrupting NREM-related oscillations or NE dynamics. The synchronized infraslow cortical oscillations spanning multiple neuromodulators reveal a previously unrecognized mechanism for organizing sleep architecture.

Astrocytes control neural communications by influencing GABAergic transmission through uptake and synthesis of GABA. Impaired GABAergic signaling is thought to underlie cortical hyperexcitability in autism. Here we show that dysregulation of astrocyte GABA transport in Fragile X syndrome (FXS), a leading genetic cause of autism, contributes to circuit hyperexcitability. Human FXS astrocytes derived from patient-specific induced pluripotent stem cells and mouse Fmr1 knockout (KO) astrocytes display a significant increase in levels of GABA and GABA-synthesizing enzyme GAD65/67. Our astrocyte-specific Fmr1 KO (cKO) mouse model reveals reduced inhibitory connectivity and impaired cortical responses to sound. Abnormal GABA transport in cortical astrocytes contributes to impaired fidelity of temporal processing and abnormal behaviors in cKO mice. Blocking astrocyte GABA transport enables higher PV expression, improves EEG responses to frequency-modulated sound, and corrects aberrant exploratory behavior. Our findings suggest astrocyte GABA transport plays a key role in regulating cortical inhibition, and contributes to autism-associated phenotypes.

The entorhinal-hippocampal system constitutes a pivotal neural circuit in the central nervous system. It is critically involved in processing spatial learning and memory. However, the specific neural interactions between entorhinal inputs and intra-hippocampal subcircuits that underlie spatial coding remain elusive. To address this gap, we integrated multimodal approaches including in vivo calcium imaging, dual-color optogenetic manipulation, chemogenetic intervention, electrophysiological recordings, immunohistochemistry, and Morris water maze (MWM) behavior to dissect how entorhinal-hippocampal afferents modulate hippocampal computations. Intriguingly, CA1-projecting CA3 neurons exhibited pronounced hyperactivity during early spatial learning, with activity gradually declining after sustained task performance. Chemogenetic inactivation of medial entorhinal-hippocampal afferents attenuated both neural responses of CA1-projecting CA3 neurons and the performance of spatial learning, hinting that medial entorhinal cortex (MEC) inputs to the hippocampus are essential for animals to execute spatial tasks precisely. By implementing dual-light theta-burst stimulation to co-activate ChrimsonR-expressing CA3-CA1 afferents and Chronos-expressing MEC-CA1 terminals, we observed robust heterosynaptic long-term potentiation in the dorsal CA1 region in vitro brain slice. This neuroplasticity was mediated synergistically by activating both NMDA receptors and voltage-gated calcium channels. Our findings establish that entorhinohippocampal afferents exert multilevel regulatory control over hippocampal function, thereby advancing mechanistic understanding of memory-related neurological pathologies.

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.

The flexibility of human vocal production is well studied, but the direct role of the auditory system in regulating vocalizations in rodents remains largely unexplored. We show that during vocalizations, a fraction of rat auditory cortex neurons shows pre-call activity and different patterns of responses during calls and playback of calls. Additionally, we classified five auditory cortical vocalization responses: pre-call activated, onset activated, onset suppressed, ramping activated and ramping suppressed neurons. Intriguingly, onset suppressed cells can predict vocalization duration and occurrence. Injecting the auditory cortex with muscimol (GABA_A receptor agonist) prolonged vocalizations, while injecting the auditory cortex with gabazine (GABA_A receptor antagonist) shortened them. Similar reductions in call duration were observed during external white-noise stimulation of the auditory cortex and/or other auditory brain structures, resembling the effects of gabazine. Together, neuronal recordings, pharmacological interference and noise induced vocal modifications indicate direct modulation of vocal productions by the rat auditory cortex.

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.

Reward processes have traditionally been ascribed to dopamine (DA)–associated circuits. While external stimuli, such as food and drugs of abuse, are activators of DA-neuron activity, growing evidence indicates that interoceptive signals also play a critical role. Among these, the gut-brain vagal axis has emerged as a key regulator, although its precise contribution to mesolimbic DA signaling and behavior remains unclear. Here, we combine complementary ex vivo and in vivo approaches across multiple scales to show that gut-brain vagal tone is essential for gating mesolimbic DA system activity and functions, modulating DA-dependent molecular and cellular processes, and scaling both food- and drug-induced reinforcement. These findings challenge the traditional brain-centric view of reward processing, supporting a more integrated model in which vagus-mediated interoceptive signals intrinsically shape motivation and reinforcement. By uncovering the influence of gut-brain vagal communication on DA functions, this work provides insights into the neurobiology of adaptive and maladaptive reward, with broad relevance for eating disorders and addiction.

Optical coherence tomography (OCT) has allowed in vivo recording of sound-induced vibrations of different regions within the organ of Corti complex (OCC), including the basilar membrane (BM), outer hair cell/Deiters cell (OHC/DC) region, and reticular lamina (RL). In the hook region of the gerbil cochlea, where measurements can be made with a substantially transverse optical axis, the three regions have different and characteristic motion responses: The OHC/DC region has greater motions than the other two regions at frequencies below the best frequency (sub-BF); the RL region typically has the greatest BF peak and smallest sub-BF motion. The phase of the OHC/DC-region motion increasingly lags BM motion phase as frequency increases; the RL-region motion phase leads BM, but with a relatively small value. All three regions are compressively nonlinear in the BF peak, but only the OHC/DC region shows sub-BF compressive nonlinearity. In this paper, we describe the strain that exists within the RL and OHC-body regions. These strains are large where the motion varies over short distances, and a region of large strain can be as short as a single 2.7 µm measurement pixel, or extend over several pixels, with the extensive strains appearing more often at 70 than at 50 dB SPL. Beyond the region of large strain, over a distance that can exceed 20 μm, the OHC/DC region displays nearly unvarying motion spatially -- this region appears to vibrate as a body. Statement of Significance The sensory tissue of the cochlea responds actively to a sound stimulus: cell-based forces amplify and enhance the vibration of the sensory tissue. Measurements employing optical coherence tomography have identified major vibration patterns along a sensory-tissue-spanning line that includes the active outer hair cells. In this article, we describe the transitional motion between these major vibration regions and the motion strains that exist as vibration morphs from one region to the next. The findings are presented in frequency response curves to convey the frequency tuning and its stimulus-level dependence, and in one-dimensional heat maps to convey the extent of regional motions and strains. These findings fuel and constrain conceptual and physics-based models of cochlear amplification.

SignificanceAlthough the transmission of auditory information in the brain has been extensively studied, the mechanism underlying fine auditory discrimination remains incompletely understood. The basal region of the ventromedial nucleus of the thalamus (bVM) has recently been found to convey frequency-specific auditory information to the primary auditory cortex (A1). Inhibition of the bVM significantly impairs fine auditory discrimination in mice. These findings indicate that the bVM plays an important role in frequency information processing. However, direct functional evidence for tonotopic organization within the bVM is still lacking.AimWe aimed to investigate whether bVM neurons exhibit a spatially ordered frequency preference, using a simple yet efficient in vivo functional mapping strategy.ApproachTo characterize the response properties of bVM neurons projecting to A1, we combined Cre-dependent retrograde viral labeling with fiber photometry in awake mice. Using a “one recording site per animal” strategy, we systematically recorded from 26 distinct locations and successfully reconstructed the tonotopic map of the bVM.ResultsWe identified a mediolateral tonotopic gradient within the bVM, with best frequencies progressing from low in medial regions to high in lateral regions.ConclusionsOur findings provide direct functional evidence of tonotopic organization within the bVM, supporting its role as an auditory relay and its contribution to fine auditory discrimination.

Coordinated neuronal activity plays an important role in information processing and transmission in the brain. While ensembles’ activity provides a more specific and less noisy version of sensory stimulus information than single neurons, their role in information transmission in the auditory pathway remains unclear. We investigated the effects of ensemble activity in the medial geniculate body (MGB) on the activation of neurons in the primary auditory cortex (A1) in female rats. MGB ensembles synchronized within narrow time windows more effectively induced A1 responses than single neurons or ensembles defined in broader time windows. This was facilitated by the convergence of ensemble inputs onto target neurons. Transmission efficacy was higher for narrow-spiking (NS) A1 neurons compared with broad-spiking (BS) neurons. Cortical UP states in isolation had no discernable effect on the transmission efficacy of thalamic cNEs. These findings highlight neuronal ensembles as focal functional units that enhance information transmission in the brain.

The basal ganglia play a key role in visual perceptual decisions. Despite being the primary target in the basal ganglia for inputs from the visual cortex, the posterior striatum's (PS) involvement in visual perceptual behavior remains unknown in rodents. We reveal that the PS direct pathway is largely segregated from the dorsomedial striatum (DMS) direct pathway, the other major striatal target for the visual cortex. We investigated the role of the PS in visual perceptual decisions by optogenetically stimulating striatal medium spiny neurons in the direct pathway (D1-MSNs) of male and female mice performing a visual change-detection task. PS D1-MSN activation robustly biased visual decisions in a manner dependent on visual context, timing, and reward expectation. We examined the effects of PS and DMS direct pathway activation on neuronal activity in the superior colliculus (SC), a major output target of the basal ganglia. Activation of either direct pathway rapidly modulated SC neurons but mostly targeted different SC neurons and had opposite effects. These results demonstrate that the PS in rodents provides an important route for controlling visual decisions, in parallel with the better-known DMS and with distinct anatomical and functional properties.

Effort is costly: given a choice, we tend to avoid it1. However, in many cases, effort adds value to the ensuing rewards2. From ants3 to humans4, individuals prefer rewards that had been harder to achieve. This counterintuitive process may promote reward seeking even in resource-poor environments, thus enhancing evolutionary fitness5. Despite its ubiquity, the neural mechanisms supporting this behavioural effect are poorly understood. Here we show that effort amplifies the dopamine response to an otherwise identical reward, and this amplification depends on local modulation of dopamine axons by acetylcholine. High-effort rewards evoke rapid acetylcholine release from local interneurons in the nucleus accumbens. Acetylcholine then binds to nicotinic receptors on dopamine axon terminals to augment dopamine release when reward is delivered. Blocking the cholinergic modulation blunts dopamine release selectively in high-effort contexts, impairing effortful behaviour while leaving low-effort reward consumption intact. These results reconcile in vitro studies, which have long demonstrated that acetylcholine can trigger dopamine release directly through dopamine axons6-11, with in vivo studies that failed to observe such modulation12-14, but did not examine high-effort contexts. Our findings uncover a mechanism that drives effortful behaviour through context-dependent local interactions between acetylcholine and dopamine axons.

Melanocytes are important components of the inner-ear cellular architecture. However, limited morphological research hinders our understanding of inner-ear function. Here, we characterize the morphology of inner-ear melanocytes and cells often misidentified as melanocytes. Immunofluorescence, smart-seq, transmission/field emission scanning electron microscopy, and immunoelectron microscopy are used. Cells previously referred to as "perivascular macrophage-like melanocytes" are not observed in the stria vascularis and are actually macrophages; along with melanocytes, they constitute intermediate cells. Cells with a "black ball" appearance in the vestibule are identified as macrophages. We examine variation in melanocytes or macrophages with age, strain, and cisplatin injury. Kir4.1 expression and the greater noise resistance observed in pigmented mice suggest melanocyte functions. Based on melanin distribution in Pou3f4y/- mice, we hypothesize that melanocytes migrate from the modiolus along Reissner's membrane area to the stria vascularis, following a base-to-apex gradient. These findings provide novel ultrastructural and immunological insights into inner-ear function.

Noise‐induced hearing loss (NIHL) is a common cause of acquired sensorineural hearing loss. Excessive endoplasmic reticulum (ER) stress‐induced apoptosis of cochlear hair cells contributes to NIHL. ER autophagy (ER‐phagy) is a critical pathway for maintaining ER homeostasis and cell survival. DDRGK1 (DDRGK domain containing 1) is a crucial receptor in ER‐phagy, essential for the removal of injured ER components. This work investigates the involvement of DDRGK1‐mediated ER‐phagy in NIHL, which has remained unclear. ER‐phagy flux is inhibited in HEI‐OC1 cells treated with hydrogen peroxide. Noise exposure reduces XIAP (X‐linked inhibitor of apoptosis protein) and DDRGK1 protein levels in these cells. Moreover, XIAP binds to DDRGK1, increasing the stability of DDRGK1 and activating ER‐phagy. Notably, in noise‐exposed CBA/CaJ mice, gastrodin, a traditional Chinese medicine ingredient, reduces noise‐induced loss of cochlear hair cells, ribbon synaptic damage, and hearing loss by promoting XIAP expression, thereby increasing DDRGK1 protein levels and activating ER‐phagy. These findings highlight XIAP‐DDRGK1‐mediated ER‐phagy as a novel therapeutic target for NIHL treatment.

Noise-induced hearing loss (NIHL) can be either temporary or permanent, depending on the intensity and duration of noise exposure. Excessive noise exposure activates various cellular mechanisms in the cochlea, including oxidative stress, immune responses, and apoptosis. Still, the mechanisms underlying hearing recovery after transient threshold shift (TTS) and lack of recovery after permanent threshold shift (PTS), as well as their therapeutic implications for NIHL, remain unknown. In this study, we performed a comparative analysis of longitudinal changes in the cochlear transcriptome of TTS and PTS mouse models. Our analysis revealed that noise-induced ER stress activates the unfolded protein response (UPR). Notably, the protein kinase R-like endoplasmic reticulum kinase (PERK) branch of the UPR returned to baseline levels following TTS but showed sustained activation following PTS. In addition, the proapoptotic factor C/EBP homologous protein (CHOP) was selectively induced in hair cells following PTS. Administering a PERK inhibitor prior to and following noise exposure hindered hearing restoration after TTS, indicating a requirement for PERK activation in hearing recovery. Inhibition of sustained PERK activation via a PERK inhibitor or reduction of CHOP expression via pharmacological chaperones facilitated partial hearing recovery following PTS. Together, these findings provide insight into the mechanisms underlying NIHL and its prevention, highlighting UPR modulation as a promising therapeutic strategy.