Publications using the RP2.1

Animals make decisions based on the value of potential outcomes. This perceived value is not fixed; it changes depending on internal needs, such as hunger or thirst, and past experiences. The basolateral amygdala (BLA) is known to be crucial for updating predicted reward values. However, it has been unclear how the BLA represents the specific value of different rewards. Two-photon calcium imaging in male mice showed that population response magnitude scaled with subjective value, and different rewards recruited distinct neuronal subpopulations. Value representations quickly re-scaled when a novel, higher-value reward appeared, and internal state shaped them: thirst selectively boosted responses to water, whereas aversive experience dampened sucrose responses. Thus, BLA circuits carry flexible, stimulus-specific value signals that integrate relative value and current affective or homeostatic conditions, providing a neural basis for adaptive decision making and learning. Our findings reveal that the BLA maintains adaptable, reward-specific value signals, essential for guiding choices according to current needs and changing circumstances.

The preservation of synaptic integrity and physiological activity is pivotal for post-traumatic auditory rehabilitation following acoustic overexposure. Neuritin, a neurotrophic factor that facilitates synapse formation, maturation, and enhanced synaptic transmission, is essential for synapse development. In this study, we established a noise-induced cochlear synaptopathy model in CBA/CaJ mice, revealing a temporal association between endogenous Neuritin expression and synaptic density. Furthermore, administration of recombinant Human Neuritin (rhNeuritin) effectively preserves synaptic density in the cochlear basal turn at 7 days and 14 days following noise exposure. Importantly, it preserves the density of functional synapses (represented by overlapping CtBP2 and GluA2 puncta) and synapse function (indicated by ABR I wave amplitudes), thus diminishing the impairment of auditory function. In addition, rhNeuritin reverses the decrease in phosphorylated extracellular signal-regulated protein kinase 1/2 (p-ERK1/2) levels resulting from noise exposure. By primarily preserving both the number and functionality of synapses in the basal turn, potentially via the induction of ERK1/2 phosphorylation, rhNeuritin mitigated hearing loss. These findings underscore the protective efficacy of rhNeuritin against noise-induced synaptic injury.

Introduction Tinnitus is the perception of non-meaningful sound in the absence of external stimuli. Although tinnitus behavior in animal models is associated with altered central nervous system activity, it is not currently possible to identify tinnitus using neuronal activity alone. In the mouse inferior colliculus (IC), a subpopulation of neurons demonstrates a sustained increase in spontaneous activity after a long-duration sound (LDS). Methods Here, we use the “ LDS test ” to reveal tinnitus-specific differences in sound-evoked plasticity through IC extracellular recordings and the auditory brainstem response (ABR LDS ) in CBA/CaJ mice after sound exposure and behavioral tinnitus assessment. Results Sound-exposed mice showed stronger and shorter tone-evoked responses in the IC compared to unexposed controls, but these differences were not strong predictors of tinnitus. In contrast, in the LDS test, non-tinnitus mice had a significantly stronger suppression in tone-evoked spike rate compared to tinnitus and unexposed control mice. ABR peak amplitudes also revealed robust differences between tinnitus and non-tinnitus mice, with ABR peaks from non-tinnitus mice exhibiting significantly stronger suppression in the LDS test compared to tinnitus and control mice. No significant differences were seen between cohorts in ABR amplitude, latency, wave V:I ratio, wave V:III ratio, I-V intra-peak latency, and I-VI intra-peak latency. We found high-frequency tone stimuli better suited to reveal tinnitus-specific differences for both extracellular IC and ABR recordings. Discussion We successfully used the LDS test to demonstrate that tinnitus-specific differences in sound-evoked plasticity can be shown using both multi-unit near-field recordings in the IC and non-invasive far-field recordings, providing a foundation for future electrophysiological research into the causes and treatment of tinnitus.

To navigate real-world listening conditions, the auditory system relies on the integration of multiple sources of information. However, to avoid inappropriate cross-talk between inputs, highly connected neural systems need to strike a balance between integration and segregation. Here, we develop a novel approach to examine how repeated neurochemical modules in the mouse inferior colliculus lateral cortex (LC) allow controlled integration of its multimodal inputs. The LC had been impossible to study via imaging because it is buried in a sulcus. Therefore, we coupled two-photon microscopy with the use of a microprism to reveal the first-ever sagittal views of the LC to examine neuronal responses with respect to its neurochemical motifs under anesthetized and awake conditions. This approach revealed marked differences in the acoustic response properties of LC and neighboring non-lemniscal portions of the inferior colliculus. In addition, we observed that the module and matrix cellular motifs of the LC displayed distinct somatosensory and auditory responses. Specifically, neurons in modules demonstrated primarily offset responses to acoustic stimuli with enhancement in responses to bimodal stimuli, whereas matrix neurons showed onset response to acoustic stimuli and suppressed responses to bimodal stimulation. Thus, this new approach revealed that the repeated structural motifs of the LC permit functional integration of multimodal inputs while retaining distinct response properties.

Background: Xeroderma pigmentosum (XP) is caused by impaired DNA repair of UV-induced dipyrimidine-photoproducts. XP cells also show impaired repair/removal of ROS or oxidative DNA lesions caused by UV or 4-nitroquinolline 1-oxide (4NQO). Gene profiling indicated that inflammatory response-related genes are significantly upregulated after UV exposure in XP-A model mice. Objective: Since XP cells are in the state of oxidative stress and inflammation, we aimed to search for therapeutic agents from anti-oxidants/anti-inflammatory drugs, that potentially improve XP symptoms. Methods: Several antioxidants were examined for reducing 4NQO-induced oxidative cytotoxicity or UV-induced oxidative DNA damage in XP-A cells. Among them, we focused on melatonin and evaluated its improving effect for Xpa-deficient MEF on UV-induced cytotoxicity and ROS production, and for Xpa-deficient mice on UV-induced skin tumorigenesis and auditory brainstem responses as one of the neurological symptoms. Results: Melatonin and nicotinamide attenuated 4NQO-induced oxidative cytotoxicity. UV-induced intracellular ROS production and cytotoxicity were improved by melatonin for Xpa-deficient MEF. Finally, the administration of melatonin mitigated UV-induced skin inflammation and tumorigenesis and suppressed hearing deterioration in Xpa-deficient mice. Conclusion: Our results show that melatonin could alleviate XP symptoms through its anti-inflammatory and antioxidant properties.

CRISPR-Cas13 systems have therapeutic promise for the precise correction of point mutations in RNA. Using adenosine deaminase acting on RNA (ADAR) effectors, A-I base conversions can be targeted using guide RNAs (gRNAs). We compare the Cas13 effectors PspCas13b and Cas13bt3 for the repair of the gene USH2A , a common cause of inherited retinal disease and Usher syndrome. In cultured cells, we demonstrate up to 80% efficiency for the repair of the common c.11864 G > A and its murine equivalent c.11840 G > A, across different gRNAs and promoters. We develop and characterize a mouse model of Usher syndrome carrying the c.11840 G > A mutation designed for the evaluation of base editors for inherited retinal disease. Finally, we compare Cas13 effectors delivered via AAV for the repair of Ush2a in photoreceptors. Mean RNA editing rates in photoreceptors across different constructs ranged from 0.32% to 2.04%, with greater efficiency in those injected with PspCas13b compared to Cas13bt3 constructs. In mice injected with PspCas13b constructs, usherin protein was successfully restored and correctly localized to the connecting cilium following RNA editing. These results support the development of transcriptome targeting gene editing therapies for retinal disease.

Perception of the environment is multimodal in nature, with sensory systems intricately interconnected. The ability to integrate multimodal sensations while preserving the distinct characteristics of each sensory modality is crucial, and the underlying mechanisms of the organization that facilitate this process require further elucidation. In the auditory system, although the concept of core and shell pathways is well established, the brain-wide input/output relationships of thalamic regions projecting to auditory-responsive cortical areas remain insufficiently studied, particularly in relation to non-auditory structures. In this study, we utilized functional imaging and viral tracing techniques to map the brain-wide connections of core and shell pathways. We identified three distinct shell pathways, in addition to a core pathway, each exhibiting unique associations with non-auditory structures involved in behavior, emotion, and other functions. This architecture suggests that these pathways contribute differentially to various aspects of multimodal sensory integration.

Noise exposure is one of the most common causes of hearing loss and hyperacusis. Studies have shown that noise exposure can induce a cortical gain to compensate for reduced input of the cochlea, which may contribute to the increased sound sensitivity. However, many people with hyperacusis have no measurable cochlear lesion after being exposed to loud sound. In this experiment, we studied the neurological alterations in the cortical and subcortical areas following a prolonged moderate level of noise exposure (84 dB SPL, 8 h/day for 4 weeks) in the laboratory mice. The cochlear function was monitored by auditory brainstem responses (ABRs). The behavioral auditory sensitivity and temporal processing were evaluated using the acoustic startle response (ASR) and gap‐induced prepulse inhibition (gap‐PPI). The central auditory functions were determined by electrophysiological recordings of the inferior colliculus (IC) and the auditory cortex (AC). Our results showed that although there was no significant difference in the ABR thresholds, the noise group showed enhanced ASR and gap‐PPI compared to the control group. Increased neural activity in both the IC and the AC was recorded in the noise‐exposed mice compared to the control group, suggesting a central gain in both the subcortical and cortical regions. The current source density (CSD) analysis of the AC response revealed an increased columnar excitation and reduced corticocortical projection in the noise group, different from the central gain model of noise‐induced hearing loss. Our results suggest that chronic “nondestructive” noise can increase the gain of the central auditory system by altering the balance of auditory thalamocortical and intracortical inputs, which may contribute to the increased sound sensitivity in people with normal hearing.

Introduction In primary auditory cortex (A1), nicotinic acetylcholine receptors (nAChRs) containing α2 subunits are expressed in layer 5 Martinotti cells (MCs)—inhibitory interneurons that send a main axon to superficial layers to inhibit distal apical dendrites of pyramidal cells (PCs). MCs also contact interneurons in supragranular layers that, in turn, inhibit PCs. Thus, MCs may regulate PCs via inhibition and disinhibition, respectively, of distal and proximal apical dendrites. Auditory inputs to PCs include thalamocortical inputs to middle layers relaying information about characteristic frequency (CF) and near-CF stimuli, and intracortical long-distance (“horizontal”) projections to multiple layers carrying information about spectrally distant (“nonCF”) stimuli. CF and nonCF inputs integrate to create broad frequency receptive fields (RFs). Systemic administration of nicotine activates nAChRs to “sharpen” RFs—to increase gain within a narrowed RF—resulting in enhanced responses to CF stimuli and reduced responses to nonCF stimuli. While nicotinic mechanisms to increase gain have been identified, the mechanism underlying RF narrowing is unknown. Methods Here, we examine the role of α2 nAChRs in mice with α2 nAChR-expressing neurons labeled fluorescently, and in mice with α2 nAChRs genetically deleted. Results The distribution of fluorescent neurons in auditory cortex was consistent with previous studies demonstrating α2 nAChRs in layer 5 MCs, including nonpyramidal somata in layer 5 and dense processes in layer 1. We also observed label in subcortical auditory regions, including processes, but no somata, in the medial geniculate body, and both fibers and somata in the inferior colliculus. Using electrophysiological (current-source density) recordings in α2 nAChR knock-out mice, we found that systemic nicotine failed to enhance CF-evoked inputs to layer 4, suggesting a role for subcortical α2 nAChRs, and failed to reduce nonCF-evoked responses, suggesting that α2 nAChRs regulate horizontal projections to produce RF narrowing. Discussion The results support the hypothesis that α2 nAChRs function to simultaneously enhance RF gain and narrow RF breadth in A1. Notably, a similar neural circuit may recur throughout cortex and hippocampus, suggesting widespread conserved functions regulated by α2 nAChRs.

Here, we report a magnetogenetic system, based on a single anti-ferritin nanobody-TRPV1 receptor fusion protein, which regulated neuronal activity when exposed to magnetic fields. Adeno-associated virus (AAV)–mediated delivery of a floxed nanobody-TRPV1 into the striatum of adenosine-2a receptor–Cre drivers resulted in motor freezing when placed in a magnetic resonance imaging machine or adjacent to a transcranial magnetic stimulation device. Functional imaging and fiber photometry confirmed activation in response to magnetic fields. Expression of the same construct in the striatum of wild-type mice along with a second injection of an AAVretro expressing Cre into the globus pallidus led to similar circuit specificity and motor responses. Last, a mutation was generated to gate chloride and inhibit neuronal activity. Expression of this variant in the subthalamic nucleus in PitX2-Cre parkinsonian mice resulted in reduced c-fos expression and motor rotational behavior. These data demonstrate that magnetogenetic constructs can bidirectionally regulate activity of specific neuronal circuits noninvasively in vivo using clinically available devices.

Neural circuits in the auditory brainstem compute interaural time and intensity differences used to determine the locations of sound sources. These circuits display features that are specialized for these functions. The projection from the ventral cochlear nucleus (VCN) to the medial nucleus of the trapezoid (MNTB) body travels along highly myelinated fibers and terminates in the calyx of Held. This monoinnervating synapse emerges during development as multiple inputs are eliminated. We previously demonstrated that elimination of microglia with a colony stimulating factor-1 inhibitor results in impaired synaptic pruning so that multiple calyceal terminals reside on principal cells of MNTB. This inhibitor also resulted in impaired auditory brainstem responses (ABRs), with elevated thresholds and increased peak latencies. Loss of the microglial fractalkine receptor, CX3CR1, decreased peak latencies in the ABR. The mechanisms underlying these effects are not known. One prominent microglial signaling pathway involved in synaptic pruning and plasticity during development and aging is the C1q-initiated compliment cascade. Here we investigated the classical complement pathway initiator, C1q, in auditory brainstem maturation. We found that C1q expression is detected in the MNTB by the first postnatal week. C1q levels increased with age and were detected within microglia and surrounding the soma of MNTB principal neurons. Loss of C1q did not affect microglia-dependent calyceal pruning. Excitatory and inhibitory synaptic markers in the MNTB and LSO were not altered with C1q deletion. ABRs showed that C1q KO mice had normal hearing thresholds but shortened peak latencies. Altogether this study uncovers the developmental time frame of C1q expression in the sound localization pathway and shows a subtle functional consequence of C1q knockdown.

The gene FOXP2 is well established for a role in human speech and language; far less is known about FOXP1 . However, this related gene has also been implicated in human language development as well as disorders associated with features of autism spectrum disorder (ASD). FOXP1 protein expression has also recently been identified in the cerebellum—a neural structure previously shown to express FOXP2 protein. The current study sought to elucidate the behavioral implications of a conditional knock‐out of Foxp1 using an En1‐Cre driver, which is active in the entirety of the cerebellum and a subset of neurons in the midbrain and spinal cord, in mice using a test battery including motor tasks associated with cerebellar dysfunction, as well as communicative and autistic‐relevant behaviors. Male and female mice with a conditional knock‐out (cKO, n = 31) and wildtype littermate controls (WT, n = 34) were assessed for gross and orofacial motor control, motor‐coordination learning, locomotion, social behavior, anxiety, auditory processing and expressive vocalizations. Overall results suggest Foxp1 plays a specific role in the development of communicative systems, and phenotypic expression of disruptions may interact with sex. Robust motor deficits associated with Foxp1 protein loss may particularly affect vocalizations based on significant orofacial motor deficits in cKO subjects could also contribute to vocalization anomalies. In summary, the current study provides key insights into the role of Foxp1 in cerebellar function and associated behaviors in mice, with implications for an improved understanding of communicative and motor‐based neurodevelopmental disabilities in humans.

Homeostatic plasticity, the ability of neurons to maintain their averaged activity constant around a set point value, is thought to account for the central hyperactivity after hearing loss. Here, we investigated the putative role of GABAergic neurotransmission in this mechanism after a noise-induced hearing loss larger than 50 dB in high frequencies in guinea pigs. The effect of GABAergic inhibition is linked to the normal functioning of K + –Cl– co-transporter isoform 2 (KCC2) which maintains a low intracellular concentration of chloride. The expression of membrane KCC2 were investigated before and after noise trauma in the ventral and dorsal cochlear nucleus (VCN and DCN, respectively) and in the inferior colliculus (IC). Moreover, the effect of gabazine (GBZ), a GABA antagonist, was also studied on the neural activity in IC. We show that KCC2 is downregulated in VCN, DCN and IC 3 days after noise trauma, and in DCN and IC 30 days after the trauma. As expected, GBZ application in the IC of control animals resulted in an increase of spontaneous and stimulus-evoked activity. In the noise exposed animals, on the other hand, GBZ application decreased the stimulus-evoked activity in IC neurons. The functional implications of these central changes are discussed.

Medial olivocochlear (MOC) efferents modulate outer hair cell motility through specialized nicotinic acetylcholine receptors to support encoding of signals in noise. Transgenic mice lacking the alpha9 subunits of these receptors (α9KOs) have normal hearing in quiet and noise, but lack classic cochlear suppression effects and show abnormal temporal, spectral, and spatial processing. Mice deficient for both the alpha9 and alpha10 receptor subunits (α9α10KOs) may exhibit more severe MOC-related phenotypes. Like α9KOs, α9α10KOs have normal auditory brainstem response (ABR) thresholds and weak MOC reflexes. Here, we further characterized auditory function in α9α10KO mice. Wild-type (WT) and α9α10KO mice had similar ABR thresholds and acoustic startle response amplitudes in quiet and noise, and similar frequency and intensity difference sensitivity. α9α10KO mice had larger ABR Wave I amplitudes than WTs in quiet and noise. Other ABR metrics of hearing-in-noise function yielded conflicting findings regarding α9α10KO susceptibility to masking effects. α9α10KO mice also had larger startle amplitudes in tone backgrounds than WTs. Overall, α9α10KO mice had grossly normal auditory function in quiet and noise, although their larger ABR amplitudes and hyperreactive startles suggest some auditory processing abnormalities. These findings contribute to the growing literature showing mixed effects of MOC dysfunction on hearing.

Listeners performed two different tasks in which they remembered short sequences comprising either complex tones (generally heard as one melody) or everyday sounds (generally heard as separate objects). In one, listeners judged whether a probe item had been present in the preceding sequence. In the other, they judged whether a second sequence of the same items was identical in order to the preceding sequence. Performance on the first task was higher for everyday sounds; performance on the second was higher for complex tones. Perceptual organization strongly shapes listeners' memory for sounds, with implications for real-world communication.

Identifying different sleep stages in humans and other mammals has traditionally relied on electroencephalograms. Such an approach is not feasible in certain animals such as invertebrates, although these animals could also be sleeping in stages. Here, we perform long-term multichannel local field potential recordings in the brains of behaving flies undergoing spontaneous sleep bouts. We acquired consistent spatial recordings of local field potentials across multiple flies, allowing us to compare brain activity across awake and sleep periods. Using machine learning, we uncover distinct temporal stages of sleep and explore the associated spatial and spectral features across the fly brain. Further, we analyze the electrophysiological correlates of microbehaviors associated with certain sleep stages. We confirm the existence of a distinct sleep stage associated with rhythmic proboscis extensions and show that spectral features of this sleep-related behavior differ significantly from those associated with the same behavior during wakefulness, indicating a dissociation between behavior and the brain states wherein these behaviors reside.

Social behaviors often consist of a motivational phase followed by action. Here we show that neurons in the ventromedial hypothalamus ventrolateral area (VMHvl) of mice encode the temporal sequence of aggressive motivation to action. The VMHvl receives local inhibitory input (VMHvl shell) and long-range input from the medial preoptic area (MPO) with functional coupling to neurons with specific temporal profiles. Encoding models reveal that during aggression, VMHvl shellvgat+ activity peaks at the start of an attack, whereas activity from the MPO-VMHvlvgat+ input peaks at specific interaction endpoints. Activation of the MPO-VMHvlvgat+ input promotes and prolongs a low motivation state, whereas activation of VMHvl shellvgat+ results in action-related deficits, acutely terminating attack. Moreover, stimulation of MPO-VMHvlvgat+ input is positively valenced and anxiolytic. Together, these data demonstrate how distinct inhibitory inputs to the hypothalamus can independently gate the motivational and action phases of aggression through a single locus of control.

Accurate time perception is crucial for hearing (speech, music) and action (walking, catching). Motor brain regions are recruited during auditory time perception. Therefore, the hypothesis was tested that children (age 6-7) at risk for developmental coordination disorder (rDCD), a neurodevelopmental disorder involving motor difficulties, would show non-motor auditory time perception deficits. Psychophysical tasks confirmed that children with rDCD have poorer duration and rhythm perception than typically developing children (N = 47, d = 0.95-1.01). Electroencephalography showed delayed mismatch negativity or P3a event-related potential latency in response to duration or rhythm deviants, reflecting inefficient neural processing (N = 54, d = 0.71-0.95). These findings are among the first to characterize perceptual timing deficits in DCD, suggesting important theoretical and clinical implications.

The hearing abilities of mammals are impacted by factors such as social cues, habitat, and physical characteristics. Despite being used commonly to study social behaviors, hearing of the monogamous prairie vole (Microtus ochrogaster) has never been characterized. In this study, anatomical features are measured and auditory brainstem responses (ABRs) are used to measure auditory capabilities of prairie voles, characterizing monaural and binaural hearing and hearing range. Sexually naive male and female voles were measured to characterize differences due to sex. It was found that prairie voles show a hearing range with greatest sensitivity between 8 and 32 kHz, binaural hearing across interaural time difference ranges appropriate for their head sizes. No differences are shown between the sexes in binaural hearing or hearing range (except at 1 kHz), however, female voles have increased amplitude of peripheral ABR waves I and II and longer latency of waves III and IV compared to males. The results confirm that prairie voles have a broad hearing range, binaural hearing consistent with rodents of similar size, and differences in amplitudes and thresholds of monaural physiological measures between the sexes. These data further highlight the necessity to understand sex-specific differences in neural processing that may underly variability in responses between sexes.