Publications using TDT

Large language models (LLMs) capture long-range contextual structure in natural language and have recently been shown to align with the human brain’s contextualized linguistic encoding. This makes them a promising computational probe for studying how context-dependent linguistic information is represented during natural speech perception. Speech perception often occurs in multi-talker environments, where attention must dynamically select among competing streams, yet how contextual information from attended and unattended speech is neurally encoded remains underexplored. Here, we investigate how auditory attention modulates neural tracking of context-dependent linguistic representations using electrocorticography (ECoG) and stereoelectroencephalography (sEEG) recordings from three epilepsy patients engaged in a two-conversation “cocktail party” paradigm. To model neural responses to attended and unattended speech streams, we used contextual word embeddings generated by large language models. We find that LLM-derived features reliably predict brain activity for the attended stream and that contextual information from the unattended stream also contributes to neural prediction. Importantly, these contributions extend beyond low-level acoustic features and shallow syntactic information, and depend on the surrounding linguistic context. Moreover, neural tracking of the unattended stream reflects shorter-range contextual integration than that of the attended stream. Together, these findings indicate that neural responses to speech reflect context-dependent linguistic representations from multiple concurrent speech streams, with attention modulating the depth and timescale of contextual integration. Our results highlight the utility of LLMs for probing higher-level linguistic representations in complex, naturalistic listening environments.

Objectives: Cisplatin is an effective anticancer drug that can induce cochleotoxicity in up to 50 to 60% of treated patients. However, the vestibulotoxic potential of cisplatin remains unclear. Our lab previously developed a multicycle model of cisplatin administration in mice that results in hearing loss similar to that observed clinically. The purpose of this study was to comprehensively characterize the functional and morphological consequences of cisplatin on the vestibular periphery in this mouse model. Design: Twenty-nine adult CBA/CaJ mice were assigned to control or cisplatin-treated groups. Cisplatin-treated mice received three consecutive cycles of once-daily cisplatin for 4 days followed by a 10-day recovery period. Mice underwent vestibular sensory evoked potential testing before cisplatin administration, after the final cycle of cisplatin, and 6 mo after treatment cessation. Mice also underwent vestibulo-ocular reflex testing and vestibular afferent single-unit recordings 6 mo after treatment cessation. Following testing, utricles, saccules, and horizontal semicircular canals were microdissected, and vestibular morphology was examined. To examine whether our data in mice were consistent with reports of cisplatin-induced vestibulotoxicity in patients, histopathology reports of human temporal bones were examined for evidence of cisplatin-induced vestibulotoxicity. Results: Vestibular sensory evoked potential thresholds were significantly elevated in cisplatin-treated mice immediately after cessation of cisplatin administration and progressively worsened 6 mo later. Rotational and translational vestibulo-ocular reflexes were generally unaffected by cisplatin. Cisplatin did not cause statistically significant changes in the spontaneous firing rates of semicircular canal afferents but did cause significant decreases in their overall regularity. No statistically significant differences in the spontaneous firing rates or regularity of otolith afferents were observed. However, cisplatin-treated mice exhibited statistically significant decreases in the percentage of low-distortion otolith afferents, indicating that responses of these afferents to head translations were more variable and less precise. Cisplatin-treated mice showed significantly decreased hair cell numbers in the saccule but not in the utricle or horizontal semicircular canal. One temporal bone histopathology report from an individual treated with high cumulative cisplatin was consistent with the results of our study, showing only saccular degeneration with normal utricle and semicircular canal morphology. Conclusions: Our study demonstrates cisplatin’s potential to affect the vestibular end organs adversely and differentially. The saccule was uniquely susceptible in our mouse model, suggesting that it may be possible to screen for cisplatin-induced vestibulotoxicity by testing saccular function. While very little is known about the potential for progression of cisplatin-induced vestibulotoxicity, our results suggest vestibular dysfunction may continue to worsen after cessation of cisplatin treatment. We recommend that ongoing and future efforts at evaluating vestibular function in patients treated with cisplatin include monitoring and evaluation of otolith function.

Hearing impairments, as a prevalent and debilitating non-motor symptom of Parkinson's disease (PD), remain unclear in mechanisms. In this work, we established PD mouse and rat models by using 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and 6-hydroxydopamine (6-OHDA), respectively, and investigated their hearing functions and potential mechanisms through auditory brainstem response (ABR), distortion product otoacoustic Emissions (DPOAE), noise exposure, immunofluorescence labeling, volumetric measurement, and colocalization analysis. In MPTP-induced PD mice, we observed significant cholinergic fibers decompensation, heterogeneous dopaminergic fibers damage of cochlear efferent fibers, and adrenergic sympathetic fibers marked loss in the osseous spiral lamina (OSL), corresponding to insignificant cochlear hair cells, ribbon synapse alteration, and auditory sensitivity injury. While in 6-OHDA-induced PD rats, asymmetric alterations in cochlear cholinergic, dopaminergic fibers were found, accompanied by inconsistent adrenergic changes in the OSL, which matched unilateral hair cells, ribbon synapse damage, and hearing loss. Overall, findings from this work indicate that pathological alterations in the cochlea of PD mice and rats, particularly in efferent fibers, may be closely relevant to peripheral hearing alterations.

Selective activation of small versus large diameter nerve fibers represents a broad challenge in the electrical modulation of neural activity for clinical applications. For example, off-target activation of motor nerve fibers was implicated in several failed vagus nerve stimulation (VNS) clinical trials by effectively limiting maximum applicable current amplitudes, thereby preventing robust activation of smaller diameter fibers responsible for therapeutic effects. Kilohertz high-frequency (HF) block is one of several strategies proposed to overcome this gap, but has yet to be thoroughly investigated in large, multifascicular, mixed nerves comparable in scale to humans. Here, we evaluated effects of HF block on the neural, muscular, and cardiac responses evoked by traditional low-frequency (LF) VNS in a large animal (swine) model. We found that HF selectively blocks neural fibers, and their associated physiological responses, in a size dependent manner with a high degree of specificity and establish initial thresholds for achieving block in large multifascicular nerves. Critically, we demonstrate that appropriately titrating HF amplitude can eliminate off-target LF-evoked motor responses while preserving activation of smaller diameter fibers targeted by clinical VNS. Beyond VNS, these data establish HF as a potentially viable strategy in any neuromodulation therapies where off-target activation of large diameter fibers limits therapeutic efficacy.

Sensorineural hearing loss (SNHL) is significantly more prevalent in individuals with chronic kidney disease (CKD) than in the general population. Although a strong independent association has been observed between kidney dysfunction and the risk of hearing loss, the underlying mechanisms linking these conditions remain poorly understood. This study investigated the pathophysiology of hearing impairment using adriamycin nephropathy (AN), a well-established animal model of CKD. AN was induced in male BALB/c mice using 10 or 12 mg/kg of adriamycin (ADR), resulting in severe kidney injury and concurrent hearing loss. ADR-treated mice exhibited significant glomerular injury, podocyte damage, and elevated renal neutrophil gelatinase-associated lipocalin (NGAL), along with increased serum creatinine and blood urea nitrogen levels. Hearing impairment was evident after 4-8 weeks of ADR treatment, as assessed by auditory brainstem response and distortion-product otoacoustic emissions, and was accompanied by cochlear hair cell loss and ribbon synapse degeneration. AN affected cochlear function by altering ion channel expression in the stria vascularis and inducing blood-labyrinth barrier (BLB) hyperpermeability, along with changes in endothelial cells, pericytes, and perivascular-resident macrophage-like melanocytes. AN significantly increased cochlear NGAL and NLRP3 levels at 4 and 8 weeks following ADR administration. NGAL was highly expressed in the tectorial membrane, cochlear neurons, and organ of Corti, while its receptor, 24p3R, was co-localized with NGAL. These findings demonstrated the role of NGAL and BLB disruption in ADR-induced SNHL, providing novel insights into the mechanistic link between CKD and hearing loss.

The hippocampus is classically linked to memory, yet increasing evidence points to a broader role in perceptual inference and deviance detection. Predictive coding theories propose that perception minimizes mismatches between expected and actual sensory input, expressed in neural signatures such as mismatch negativity (MMN) and P300. Although MMN arises mainly from sensory and prefrontal cortices, the hippocampus is anatomically interconnected with both and may also contribute to prediction error processing. We recorded single- and multi-unit activity and local field potentials (LFPs) from DG and CA1 in urethane-anesthetized rats during an auditory oddball paradigm and a no-repetition control sequence to dissociate prediction error from repetition suppression. Approximately 20% of hippocampal neurons were sound responsive, and a subset showed deviant selectivity. Spiking activity predominantly reflected prediction errors, while LFPs revealed complementary contributions from repetition suppression and prediction error. Early LFP components were enhanced for randomly presented deviants, whereas later components within the P300 latency range were stronger for predictable deviants, indicating temporally distinct phases of error signaling and top-down modulation. These findings identify the hippocampus as an active contributor to auditory deviance detection and support a hierarchical model in which hippocampal circuits participate in predictive sensory processing beyond memory.

The axon initial segment (AIS) is the site of action potential generation and exhibits structural and functional plasticity upon adaptation of neuronal excitability and disease. Performing in vivo longitudinal two-photon imaging of AIS in the medial prefrontal cortex of male mice, we reveal dynamic AIS remodeling during associative fear learning and extinction. These results demonstrate that AIS plasticity is not only crucial for homeostatic adaptation but also a hallmark of memory formation.

Primate societies rely on the production and interpretation of social signals, in particular those displayed by the face. Facial movements are controlled, according to the dominant neuropsychological schema, by two separate circuits, one originating in medial frontal cortex controlling emotional expressions, and a second one originating in lateral motor and premotor areas controlling voluntary facial movements. Despite this functional dichotomy, cortical anatomy suggests that medial and lateral areas are directly connected and may thus operate as a single network. Here, we test these contrasting hypotheses through structural and functional MRI (fMRI) guided electrical stimulation and simultaneous multichannel recordings from key facial motor areas in the macaque monkey brain. These areas include medial facial motor area M3 (located in the anterior cingulate cortex); two lateral face-related motor areas: M1 (primary motor) and PMv (ventrolateral premotor); and S1 (primary somatosensory cortex). Cortical responses evoked by intracortical stimulation revealed that medial and lateral areas can exert significant functional impact on each other. Simultaneous recordings of local field potentials in all facial motor areas further confirm that during facial expressions, medial and lateral facial motor areas significantly interact, primarily in the alpha and beta frequency ranges, whereas during voluntary chewing, coupling occurs at lower frequencies. These functional interactions varied across facial movement types. Thus, at the cortical level, the control of facial movements is not mediated through independent (medial/lateral) functional streams, but results from an interacting sensorimotor network.

The genetic factors and resulting neural circuit physiology driving variation in attention are poorly understood. Here we took an unbiased forward genetics approach to identify genes of large effect on attention. We studied 200 genetically diverse mice and, through genetic mapping, identified a small locus on chromosome 13 (95% CI 92.22-94.09 Mb) that is significantly associated with variation in pre-attentive processing. Within the locus we identified a gene, Homer1, encoding a synaptic protein, whose downregulation during development led to improvements in multiple measures of attention in adulthood. Mechanistically, reduced Homer1 levels resulted in an upscaling of GABA receptors and enhanced inhibitory tone in the prefrontal cortex, leading to improved neural signal to noise and attentional performance. We thus identify a single genetic locus of large effect on attention and propose Homer1-dependent inhibitory tone, sculpted during a developmental sensitive period, as a key regulator and potential therapeutic target for attentional performance.

Aversion to opioid withdrawal is a significant barrier to achieving lasting opioid abstinence. The central amygdala (CeA), a key brain region for pain, threat-detection, autonomic engagement, and valence assignment, is active during opioid withdrawal. However, the role of molecularly distinct CeA neural populations in withdrawal remains underexplored. Here, we investigated the activity dynamics, brain-wide connectivity, and functional contribution of Protein Kinase C-delta (PKCδ)-expressing neurons in the CeA lateral capsule (CeLC PKCδ ) during fentanyl withdrawal in mice. Mapping activity-dependent gene expression in CeLC PKCδ neurons revealed a highly withdrawal-active subregion in the anterior half of the CeA. Fiber photometry calcium imaging showed that opioid-naïve CeLC PKCδ neurons respond to salient noxious and startling stimuli. In fentanyl-dependent mice, naloxone-precipitated withdrawal increased spontaneous neural activity and enhanced responses to noxious stimuli. Chronic inhibition of CeLC PKCδ neurons throughout fentanyl exposure, via viral overexpression of the potassium channel Kir2.1, attenuated withdrawal symptoms in fentanyl-dependent mice. Lastly, we identified putative opioid-sensitive inputs to CeLC PKCδ neurons using rabies-mediated monosynaptic circuit tracing and color-switching tracers to map mu-opioid receptor-expressing inputs to the CeLC. Collectively, these findings suggest that the hyperactivity of CeLC PKCδ neurons underlies the somatic signs of fentanyl withdrawal, offering new insights into the amygdala cell-types and circuits involved in opioid dependence.

Vasomotion, vascular oscillations at ~ 0.1 Hz, may serve as a biomarker and therapeutic target for neurodegenerative diseases, but its origins, structure across brain vasculature, and correlation with neural activity remain unclear. This study examined the spatiotemporal characteristics of cerebral vasomotion and its relationship to neural activity in anaesthetised Hooded Lister rats using simultaneous recordings of neuronal activity and haemodynamics in motor and whisker barrel cortices. In a subset of rats, tissue oxygen was also measured. Blood pressure was pharmacologically modulated to alter vascular oscillations. We found that vasomotion was driven by the arterial tree. Two prominent activity patterns emerged: fast vasomotion across the entire hemisphere and slow vasomotion seen as a travelling wave running through the surface arteries. Moreover, vasomotion was associated with low tissue oxygen and was largely independent of spontaneous neural activity and therefore not a product of neurovascular coupling.

Although age-related hearing loss (ARHL) is the most common sensory loss in older adults, underlying mechanisms remain unclear. Recent genome-wide association studies (GWAS) linked variation in several genes with ARHL risk, including KLHDC7B , a gene of unknown function not previously linked to hearing. We demonstrate Klhdc7b is expressed exclusively in sensory hair cells in mouse cochlea. Utilizing two independent mouse knockout models ( Klhdc7b IMPC-/- and Klhdc7b Regn Δ/Δ ) we find that absence of Klhdc7b leads to severe early-onset, progressive hearing loss. Hair cells appear to develop normally, but outer hair cells are progressively lost from base-to-apex of the cochlea, a common pathology in ARHL. These results suggest KLHDC7B is required for maintenance rather than development, of auditory function. The validation in mouse of a human ARHL GWAS association suggests other novel candidates should be investigated. Our work provides two mouse models to study KLHDC7B function, and for development of therapeutic tools for ARHL.

Understanding how the brain rapidly processes neural information through large-scale network dynamics is fundamental to neuroscience. Resting-state fMRI (rsfMRI) captures networks by probing spontaneous neural activity fluctuations, yet whether these networks can accommodate fast, sensitive information processing remains unknown. Here, we reveal brain-wide rsfMRI network dynamics (i.e., states and their transitions) that enable fast information processing through rapid activity-triggered network reconfiguration in male rats. Following activation of a single optogenetically evoked somatosensory thalamic input, states and transitions associated with internally-oriented information processing are quickly suppressed and diverted through basal forebrain and hypothalamus to strengthen externally-oriented (i.e., sensory) processes. Simultaneous rsfMRI and electrophysiology measurements in somatosensory and cingulate cortices demonstrate that intra-regional wide-band and inter-regional narrow-band (i.e., slow-oscillations) neural activity synchronizations directly drive rsfMRI network dynamics and reconfiguration to support fast processing of single thalamic input. Our study uncovers fast interactions between neural activity and rsfMRI networks in processing single neural input.

Autism Spectrum Disorders (ASDs) are a group of neurodevelopmental disorders with heterogeneous causes, and are characterized by communication deficits, impaired social interactions, and repetitive behaviors. Despite numerous studies in mouse models focused on pathophysiological circuit mechanisms of ASD in mature animals, little is known regarding ASD onset and its evolution through development. The medial prefrontal cortex (mPFC) is crucial for higher-order cognitive functions and social behavior, thus key to understanding ASD pathology. To explore early developmental disruptions in the mPFC, we used the Shank3 knockout (Shank3-/-) mouse model. SHANK3 is crucial for glutamatergic synapse maturation, and the Shank3-/- mouse has been well-characterized for displaying ASD-related behavioral phenotypes. We investigated network, cellular, and synaptic changes within the mPFC and in its projections to the mediodorsal thalamus (MD) at two developmental stages, preweaning (P14) and adulthood (>P55). Our findings reveal early synaptic deficits at P14 both within the mPFC and in its projections to the MD accompanied by alterations in mPFC network activity and reduced excitability of excitatory neurons, overall suggesting hypofunction. Interestingly, behavioral deficits were already detectable by P11, preceding the observation of synaptic changes at P14. By adulthood, these early synaptic and cellular alterations progressed to global dysfunction, characterized by mPFC network hyperfunction and layer 5 pyramidal cell hyperexcitability, accompanied by augmented glutamatergic signaling to MD with enhanced action potential production. These results suggest that early synaptic changes may precede and interact with behavioral deficits, which might lead to compensatory mechanisms that contribute to more pronounced mPFC dysfunction later in development. This study highlights the complex dynamic progression of mPFC deficits in ASD and emphasizes the relevance of early synaptic alterations as potential contributors to later behavioral and cognitive deficits.

Auditory hypersensitivity is a prominent symptom in Fragile X syndrome (FXS), the most prevalent monogenic cause of autism and intellectual disability. FXS arises through the loss of the protein encoded by the FMR1 (Fragile X Messenger Ribonucleoprotein 1) gene, FMRP, required for normal neural circuit excitability. In the brainstem, FMRP is necessary for normal development of acoustic reactivity, and its loss has been implicated in audiogenic seizures (AGS) in Fmr1 knockout (KO) mice, modeling auditory hypersensitivity and seizures in FXS patients. The present study investigated the correlation between auditory brainstem function and behavioral expression of AGS at the early (postnatal day P20, infancy) and late (P32, juvenile) stages of auditory development in Fmr1 KO mice compared with wildtype (WT) mice, and in both females and males. We tested responsiveness to pure tones of select auditory pathway elements through auditory brainstem responses, and neural synchronization to amplitude envelopes of modulated acoustic stimuli through auditory steady‐state responses. AGS behavior was categorized for severity during 5‐min exposure to loud sound. Expression of the immediate early gene cFos was quantified as a marker for neuronal activity in the inferior colliculus. During infancy, more severe AGS expression in Fmr1 KO mice compared with WT mice was accompanied by increased responsiveness to acoustic stimuli at the level of the superior olivary complex and inferior colliculus, and stronger neural synchronicity in subcortical auditory neurons. Fmr1 KO mice also had higher cFos positive cell counts in the inferior colliculus after exposure to loud sound. With age, both AGS susceptibility and exaggerated acoustic stimulus‐evoked activity in the Fmr1 KO mice subsided. Intriguingly, Fmr1 KO mice displayed an altered developmental profile in both the threshold and amplitude of auditory brainstem response. Our findings support evidence that AGS activity relies upon hyperexcitability in the auditory system, including in the lower brainstem, possibly due to disturbed auditory maturation. Hyper‐synchronization to modulated sounds in subcortical auditory neurons seemed to predict AGS severity. The developmental trajectory of the auditory hyperresponsiveness and hypersynchrony suggests a transient processing alteration underlying heightened AGS susceptibility in Fmr1 KO mice. A better understanding of FXS‐related circuit and behavioral symptoms of auditory processing across development provides the potential to identify therapeutic strategies to achieve auditory function recovery in FXS.

Purpose Although human temporal bones suggest that cochlear synapse numbers decline with age and noise exposure, no validated diagnostic method exists. In animal models, cochlear synaptopathy is associated with reduced auditory brainstem response (ABR) wave 1 amplitude and envelope following response (EFR) magnitude for a sinusoidally amplitude modulated (SAM) tone. However, measuring SAM EFR at the optimal modulation frequency (1000 Hz) is difficult in humans. A rectangular amplitude modulated (RAM) tone may be more sensitive to synaptopathy, but this has not been validated in animals. In addition, because synaptopathy likely co-occurs with outer hair cell dysfunction (OHC), a diagnostic assay needs to be robust to abnormal auditory thresholds. The objective of this study was to evaluate the relative ability of ABR and EFR measures to predict synapse numbers in mice with varying degrees of synaptopathy and OHC dysfunction. Methods Distortion product otoacoustic emissions (DPOAEs), ABR, SAM EFR, and RAM EFR were recorded from 57 mice with a range of auditory thresholds and degrees of synaptopathy. Cross-validation was used to compare the relative ability of linear regression models incorporating different measures to predict synapse numbers. Predictions were confirmed histologically. Results RAM EFR modulated at 1000 Hz was the single best predictor of synapse numbers for broad synapse loss across frequency, while combining RAM EFR with ABR further improved predictions. In contrast, ABR best predicted focal synaptopathy. Incorporating DPOAEs improved predictions for EFR, but not ABR. Conclusion RAM EFR, ABR, and DPOAEs should be used in the future when predicting synapse numbers.

High-grade gliomas are lethal brain cancers that are powerfully regulated by glutamatergic neurons through activity-dependent paracrine factors and functional neuron-to-glioma synapses. Here, we report that serotonergic neurons promote the proliferation of high-grade gliomas throughout the brain. Serotonergic neuronal activity drives circuit-specific increases in high-grade glioma proliferation, calcium transients, and reduced survival. This growth-promoting effect is chiefly mediated by activation of the serotonin (5-hydroxytryptamine; 5HT) receptor 5HT 2A on glioma cells. Knock out or pharmacological blockade of 5HT 2A receptors in glioma abrogated the glioma growth-promoting effects of serotonergic neuronal activity, while serotonergic psychedelic drugs robustly promote malignant cell proliferation. Gliomas alter serotonergic neuronal activity patterns, resulting in elevated serotonin release into the tumor microenvironment. Together, these findings uncover pathogenic, feed-forward interactions between serotonergic neurons and glioma cells.

Haptic feedback elicits sensations of touch to communicate information to the user. Recent developments in virtual reality and sensory prostheses have demonstrated the need for systems that can provide more information than the simple vibrotactor in your phone. A novel multidimensional encoding approach allows for percepts of signal intensity and flutter frequency in a single distal location using transcutaneous neural stimulation. In this study we aimed to determine if these percepts are able to convey useful information to participants performing motor control tasks and if they perform better than a typical intensity-only modulation approach. Eleven participants performed three types of tasks to assess the efficacy of multidimensional stimulation. The first set included discrete matching tasks, where participants had to differentiate between thirteen combinations of flutter frequency and intensity. In the other two sets, participants had to differentiate between simultaneous changes in the percepts. Participants in this study could correctly identify all discrete percept combinations and follow the changes in the percepts better than chance. Performance in the discrete task using a multidimensional approach showed increased information transfer compared to the individual modulation of intensity or flutter frequency. These results suggest that multidimensional encoding is a promising approach for increasing information throughput in sensory feedback systems. Hence, such an approach might improve upon conventional methods of providing graded percepts, creating more informative tactile percepts for haptic feedback through peripheral nerve stimulation.