Behavioral Neuroscience publications

Ultrasonic vocalizations (USVs) are widely used in rodent social communication, yet the functional significance of male–male vocal interactions in mice remains unclear. Here, we investigated whether USVs produced during specific social behaviors influence the behavior of conspecifics. Using playback experiments, we compared responses to vocalizations recorded during chasing and being chased in male–male interactions. We found that USVs emitted by chased intruders consistently elicited approach behavior in receiver mice, whereas those emitted by chasing individuals did not. Acoustic analyses revealed that these vocalizations differed in syllable composition, with intruder calls containing a higher proportion of upward frequency-modulated syllables and exhibiting higher mean frequencies. In addition, the temporal organization of syllables appeared to contribute to the behavioral response. Together, these results suggest that male mice respond selectively to certain USV patterns associated with specific social contexts, indicating that acoustic features and temporal structure may jointly influence social approach behavior in mice. Highlights Behavioral context (chased vs. chasing) shapes the composition of USV syllable types Male mice selectively approach USVs from chased intruders, but not chasing residents The approach response exhibits high temporal synchrony across individual receivers Temporal organization of syllables modulates approach behavior based on acoustic features

The Gestalt laws of perceptual organization determine which image regions in a visual scene are perceived as figures or background. Convex, enclosed, and symmetric regions are more likely to be perceived as figures, but the underlying neural mechanisms are not well understood. Here, we studied the influence of Gestalt cues on visual perception and on neuronal activity in early visual cortex. We found that, in both humans and macaques, the perceived contrast of Gabor probes was generally higher when placed on Gestalt-defined figures than on background regions, although individuals differed. Neural activity in areas V1 and V4 of the visual cortex of monkeys performing a contrast discrimination task was higher for image elements belonging to Gestalt-defined figures than image-elements of the background, except for symmetry-defined figures. We observed this figure-background modulation in both V1 and V4 even when the distinction between figure and background was irrelevant for the task of the animal. The influence of Gestalt cues on neural activity was stronger in V4 than in V1, suggesting that Gestalt organization arises through modulation of neural activity in higher visual areas, which then modulates neural activity in early visual areas through feedback.

Tissue inflammation or nerve injury at the periphery can cause chronic pain. Although the spinal-cord-projecting neurons in the rostral ventromedial medulla (RVMSC neurons) can promote pain chronification1-4, the pathway by which peripheral injury signals drive these neurons is poorly understood1-3,5. Here we report a circuit loop that extends from the spinal cord to the ventral posterolateral thalamus and posterior complex of the thalamus, proceeds to the primary somatosensory cortex and returns to the spinal cord via the lateral superior colliculus, which in turn connects to μ-opioid-receptor-expressing RVMSC neurons. Silencing any node along this multisynaptic circuit has minimal effects on nociception in healthy mice, but can eliminate mechanical hypersensitization and restore normal nociceptive response thresholds in mouse models of inflammatory and neuropathic pain. In healthy mice, repetitive-but not acute-activation of each node in this circuit is sufficient to cause robust chronic mechanical hypersensitization. Our findings reveal a spino-brain-spinal cord circuit loop that links ascending and descending pathways and specifically drives chronic mechanical pain. This could enable the identification of cellular targets for treating chronic pain.

Developing safe and effective pain medications is an ongoing challenge for human health. Agonists for the µ-opioid receptor (MOR) are essential pain medications, but their high intrinsic efficacy also induces adverse side effects, including respiratory depression, constipation, tolerance, dependence, withdrawal and addiction 1–7 . Strategies to limit adverse effects traditionally include developing MOR agonists that have low intrinsic efficacy or that preferentially activate G-protein signalling over β-arrestin signalling 8 . Here we identify a novel MOR agonist with supramaximal intrinsic efficacy and a unique pharmacological profile that produced effective analgesia in rodents with minimal adverse effects. N -desethyl-fluornitrazene (DFNZ) was derived from a class of synthetic benzimidazole opioids called nitazenes. DFNZ has impaired brain penetrance, a unique spatiotemporal MOR cellular signalling profile, and diminished efficacy at the MOR–galanin 1 receptor (GAL1) heteromer. DFNZ does not induce respiratory depression, tolerance or MOR downregulation after repeated exposure. Compared with other MOR agonists, DFNZ has limited effects on dopamine neurotransmission in nucleus accumbens and weaker reinforcing effects in the drug self-administration procedure. These results provide novel insights about MOR and nitazene pharmacology, have important implications for pain and addiction treatment, and challenge the prevailing dogma that high-efficacy MOR agonists cannot constitute safe and effective therapeutic agents.

Glucose-dependent insulinotropic polypeptide (GIP) is a gut-derived incretin hormone, and pharmacologic modulation of central GIP receptors (GIPRs) improves energy homeostasis and prevents conditioned taste avoidance (CTA). However, the mechanisms by which GIPR signaling impact food intake and aversion are incompletely understood. Here, we show that GIPR agonism abrogates the aversive and enhances the anorexigenic effects of the pro-inflammatory cytokine interleukin-1β (IL-1β). Aversion-encoding parabrachial calcitonin gene-related peptide (CGRP) neurons were required for IL-1β-induced CTA but not anorexia. Moreover, systemic IL-1β increased CGRP neural activity in vivo, and this was significantly attenuated by co-administration of a GIPR agonist. By contrast, GIPR in the dorsal vagal complex was required for the acute anorectic effect of GIPR agonism but not its anti-aversive effect. Taken together, our data suggest that GIPR agonism reduces food intake and prevents aversion via distinct circuits and that GIPR agonism may represent an effective approach to alleviate inflammation-induced aversion.

Endocannabinoid (eCB) signaling is a key regulator of reward-related dopaminergic signaling, particularly in response to drugs of abuse, such as cocaine. To date, our understanding of this mechanism has primarily been limited to male subjects. Prior work establishes that female cocaine users have more adverse outcomes, and female rats show greater sensitivity to cannabinoid type 1 receptor (CB1R) regulation of cocaine self-administration. Therefore, we hypothesize that female rats exhibit enhanced eCB regulation of cocaine-evoked dopamine (DA). We used in vivo fiber photometry recording of the dopamine biosensor, dLight 1.3b, in the nucleus accumbens medial shell (NAc ms ) in response to cocaine in male and female rats. Rats were pretreated with cannabinoid-targeting drugs to investigate the effects of CB1R inactivation or augmentation of the eCB 2-AG on cocaine-evoked DA. Our results revealed that CB1R inactivation attenuates cocaine-evoked DA in male and female rats, but females showed enhanced sensitivity for CB1R regulation of cocaine-evoked DA. Cocaine-evoked DA was enhanced by augmenting 2-AG levels, and females again showed increased sensitivity to this manipulation. Finally, females show greater cocaine-evoked DA when in a non-estrous cycle compared to estrous, reinforcing that estrous cycle is a determinant of cocaine-evoked DA. These data indicate that females show enhanced eCB regulation of cocaine-evoked DA signaling, underscoring the importance of sex as a biological variable in our understanding of endocannabinoid regulation of drug reward. Highlights CB1R inactivation attenuates cocaine-evoked DA in NAc ms , preferentially in females 2-AG augmentation via MAGL inhibition enhances cocaine-evoked DA, with female bias Estrous phase modulates the dopamine response to a high dose of cocaine in females Male and female rats show similar baseline DA and locomotor responses to cocaine

Age-related hearing loss (ARHL), or presbycusis, is one of the most prevalent sensory deficits in older adults and has been increasingly implicated in cognitive decline and dementia. This study characterizes ARHL in a rhesus macaque model by combining histological, physiological, and cognitive assessments. Aged macaques exhibited progressive cochlear degeneration, with marked outer hair cell loss at mid-to-high frequencies, elevated auditory thresholds, reduced distortion product otoacoustic emissions, and impaired auditory brainstem responses including amplitude reduction, latency prolongation, and diminished temporal precision. Despite modest reductions in inner hair cell ribbon synapse counts, hypertrophic changes were observed. These auditory deficits correlated with subtle impairments in visual working memory, as measured by a delayed match-to-sample task, underscoring a potential sensory-cognitive link. By capturing cross-domain aging markers in a translationally relevant primate model, this work lays a foundation for mechanistic studies and therapeutic interventions targeting both hearing and cognition in aging populations.

Every moment, a spotlight of attention roams our visual field to enhance detection of salient stimuli. While recent work suggests how the brain selects salient relevant stimuli (attentional focus), it is unknown if there are mechanisms that modulate attention to suit fluctuating target salience or internal needs (attentional strength). Here, using optical recordings and perturbations in mice performing a cued detection task, we report that rapid dynamics in both dorsal raphe (DR) activity and cortical serotonin (5HT) release selectively regulate attentional strength. In contrast to these rapid DR-5HT dynamics, we found previously reported reward-associated and slower dynamics were both unrelated to attention. Brief optogenetic DR-5HT suppression increased attentional strength and performance, whereas optogenetic excitation reduced attentional strength and performance. A computational model suggests DR-5HT’s inverse effects on attention arise from control of cortical suppression and divisive normalization. Collectively, our results demonstrate that the brain independently controls attentional strength and focus and defines rapid DR-5HT neuromodulation as a new regulator of attentional strength.

Social relationships, including dominance status, are powerful regulators of mental health, and social experiences impact the continued expression of these behaviors. However, very little is known about the neuronal mechanisms that regulate the positive reinforcing effects of aggression that underlie social dominance, including potential sex differences. To address this gap, we used viral-mediated gene expression in Syrian hamsters to investigate how nucleus accumbens neurons regulate behavioral adaptations caused by aggression and other social interactions in both males and females. We found that females, but not males, display an increase in the efficiency to establish aggression with repeated experience. Females also displayed a more rapid potentiation of calcium signals from nucleus accumbens neurons over repeated social interactions. Chemogenetic inhibition of nucleus accumbens neurons specifically decreased aggression in females. Optogenetic stimulation of excitatory synaptic input from the prefrontal cortex to the nucleus accumbens decreased social investigation in females but increased social investigation and reduced aggression in males. Collectively, these studies suggest that the activity of nucleus accumbens neurons drives behavioral adaptations related to social interactions in general, and aggressive experience in particular, in opposite directions in females and males. This mechanism may contribute to the enhanced reward for social interactions in females compared with males and help explain the sex differences in the susceptibility to disorders associated with deficits in social behavior.

How neuronal firing within a circuit encodes behavioural intensity, like running speed, is largely unknown. Projections from temporal association cortex (TeA) and superior colliculus (SC) to dorsal periaqueductal grey (dPAG) circuit can both trigger running behaviour. Using in vivo loose-patch recordings with circuit manipulations in mice, we quantified a firing - speed relationship and established its encoding model. Here, we report two behavioural patterns induced by circuit activation: backing away and rebound running. Mechanistically, dPAG CaMKIIα neurons receiving inputs from either TeA or SC, function as distinct “behavioural units”, controlling two “unit behaviours” of running and backing away, respectively. The unidirectional inhibition from the backing away unit to the running unit is mediated by somatostatin (SOM) neurons in dPAG, enabling transitions among four behavioural states: running, backing away, stopping, and rebound running. Both running and backing away behaviours follow a unified motor encoding model, quantified by a single-phase association equation.

A central goal in neuroscience is to clarify how neural circuits translate sensory input into adaptive behaviours. Although unisensory evoked escape circuits in mice are well defined, it remains unclear whether a single nucleus contains specialized sensory, sensory‒motor decision, and motor command neurons for escapes driven by distinct sensory cues, and how these neurons form functional microcircuits. Using multiple sensory stimuli in mice, we identified the temporal association cortex (TeA) as a critical escape hub. Combining in vivo electrophysiology, optogenetics and chemogenetics, we characterized three distinct neuron subtypes within TeA layer 5 (L5) CaMKII neurons that correspond to these three functional classes. Intratelencephalic (IT) neurons serve as sensory‒motor decision neurons, while layer matched pyramidal tract (PT) neurons projecting to the dorsal periaqueductal grey (dPAG) act as motor command neurons. We reveal a laminar IT–PT microcircuit that converts sensory input into sensory-motor decisions and commands for escape locomotion.

Classic theories propose opponent functions for striatal dopamine (DA) and serotonin (5-hydroxytryptamine; 5HT), with DA promoting approach and 5HT promoting patience or avoidance. How these neuromodulators regulate downstream circuits to achieve such antagonistic effects remains mysterious. Here, we mapped striatal 5HT receptor expression in mice to reveal preferential enrichment of putatively excitatory, Gq-coupled 5HT receptors on medium spiny neurons expressing inhibitory D2 DA receptors (D2-MSNs). Acute slice recordings from genetically identified striatal neurons showed that DA and 5HT inversely regulate D2-MSN firing and confirmed that 5HT's excitatory effect on these cells is blocked by 5HT2a and 5HT2c receptor antagonists. Pharmacologically upregulating striatal 5HT release preferentially induced cfos expression in D2-MSNs, validating that 5HT's excitatory effect on these cells also occurs in vivo. Finally, 5HT2c receptor loss-of-function in D2-MSNs, but not D1-MSNs, enhanced animals' sensitivity to the behavioral effects of cocaine - a potent releaser of DA and 5HT - showing that 5HTergic excitation of D2-MSNs counteracts the reinforcing effects of striatal DA release. Altogether these results demonstrate that DA and 5HT inversely modulate D2-MSN activity to regulate cocaine reward, identifying a key circuit mechanism underlying the opponent behavioral effects of these important neuromodulators.

In the auditory cortex, neural responses to stimuli inside receptive fields (RFs) can be further facilitated by behavioral demands, such as attending to a spatial location. It is less clear how off-RF stimuli modulate neural responses and contribute to behavioral tasks. Our recent study revealed a particular form of location-specific facilitation evoked by repeated stimulation from an off-RF location, suggesting behavioral modulation of spatial RFs. To further explore this question, we trained marmosets to attend to sound locations that were either inside or outside the RFs of auditory cortical neurons. The majority of neurons showed increased firing rates at target locations inside their RFs. Interestingly, this increase also occurred outside the RFs, sometimes exceeding the responses at the RF center during passive listening. This task-related off-RF facilitation was much more common in the caudal area than in the rostral area and the primary auditory cortex. A normalization model reproduced the off-RF facilitation using widespread suppression. The model’s prediction was confirmed by experimental observations of widespread reductions in firing rate and hyperpolarized membrane potentials for off-RF stimuli. These results suggest that behavioral task demands recruit a broader range of neurons than those that are responsive to a target sound in the passive state.

In uncertain, threatening environments, rapid and flexible behavioral decisions are essential for survival. The ventral CA1 region of the hippocampus encodes threatening contexts and can regulate avoidance-related behaviors. While activity patterns in excitatory neurons of vCA1 have been well characterized, the contributions of specific interneuron subtypes to avoidance decisions in threatening situations remain to be fully elucidated. Here, we show that somatostatin expressing (SST) interneurons in vCA1 are selectively recruited during avoidance behavior and play a causal role in shaping behavioral responses in aversive spaces. We find that vCA1 SST interneurons ramp their activity in anticipation of, and during, avoidance. This contrasted with parvalbumin (PV) and vasoactive intestinal peptide (VIP) interneurons, which are preferentially active during exploratory approach behaviors. Unlike other classes of vCA1 interneurons, SST neuron activity more reliably represented the animal’s intention to avoid rather than its spatial position. Moreover, optogenetic silencing of SST interneurons reduced the efficiency of approach-avoidance decisions. These findings identify vCA1 SST interneurons as key regulators of threat assessment, revealing a cell-type-specific mechanism by which vCA1 microcircuits govern avoidance behaviors. This work provides a new framework for understanding hippocampal control of avoidance behavior and highlights SST-expressing interneurons as key contributors to anxiety-related behaviors.

Using external cues to guide behavior is a core function that enables multiple aspects of cognition and attentional control, and deficits in this process are central to many theories of neuro-psychiatric, degenerative, and developmental disorders. Cue detection relies on the precise coordination of neural circuits, with the mediodorsal thalamus (MD) hypothesized to play a pivotal role in orchestrating the relay of cue-based associative information to the prefrontal cortex. The prefrontal cortex comprises multiple subregions, which are believed to differentially contribute to such associative cue-based behaviors. This regional specificity is likely seeded by projection-defined MD→PFC pathways, although the anatomical organization of these discrete channels and their dynamic roles in cue detection are still being defined. Here, we address this gap by combining anatomical circuit mapping of MD-PFC output pathways with in vivo calcium imaging during a cue-based reward conditioning task in mice. These experiments reveal that MD projections to distinct PFC subregions (prelimbic and anterior cingulate cortex) form topographically defined loops, that are characterized by unique patterns of activity across cue-reward learning. Using fiber photometry to monitor changes in calcium activity in axonal projections from the MD to the PFC, we show that during learning, MD projections to the prelimbic subregion are activated by cue presentation, and the dynamics of this activity remain stable across training days. In contrast, MD projections to the anterior cingulate exhibit a learning-dependent suppression of activity that predicts reward approach behavior in late training. Interestingly, the two pathways exhibit opposing activity patterns when the predictive validity of the cue is diminished by extinction training, suggesting distinct functional roles in detecting violations of learned contingencies. Together, these findings reveal previously unrecognized anatomical and functional distinctions within MD-PFC circuits and demonstrate that parallel thalamocortical pathways differentially support cue detection and behavioral flexibility. This work advances understanding of thalamocortical mechanisms underlying cue detection and may inform circuit-based approaches for treating cognitive dysfunction in psychiatric disorders.

It is widely accepted that tinnitus arises from maladaptive neuroplasticity in the central auditory system, which compensates for reduced peripheral input; notably, the loss of inner hair cell (IHC) synapses is considered a key underlying factor. IHC synapses can immediately and permanently degenerate after noise exposure, independent of hair cell loss, whereas the cell bodies and central projections of cochlear neurons can survive for months to years, providing an extended therapeutic window for improving afferent input through synapse regeneration. Using NHPN-1010 (a combination of 2,4-disulfophenyl-N-tert-butylnitrone and N-acetylcysteine), we propose a delayed treatment strategy (≥ 4 weeks after trauma) for noise-induced tinnitus (NIT) in rats. NHPN-1010 enhanced gap-prepulse inhibition of acoustic startle responses-indicative of diminished tinnitus-like deficits-coupled with a concomitant upregulation of GABAergic inhibition in the dorsal cochlear nucleus, relative to vehicle alone (saline). Furthermore, NHPN-1010, compared to saline, led to increased wave-I amplitudes of auditory brainstem responses, the effect accompanied by a corresponding rise in the number of presynaptic ribbons in IHCs. Our findings suggest that NHPN-1010 plays a therapeutic role in NIT by promoting cochlear synaptogenesis and normalizing central auditory signaling.

Alzheimer's disease (AD) is a brain condition with heterogeneity in disease progression due to genetic and environmental variables. There is a critical need to better understand the relationship of AD pathologies and potential modifiable factors like hearing loss. Auditory processing measurements in AD mouse models have been reported, but the results are mixed. Most were conducted using evoked potential recordings measured under anesthesia, unlike typical hearing assessments on aging adult humans. Here, we used operant conditioning and signal detection theory to measure daily pure tone behavioral detection throughout the lifespan of trained mutant and wild-type (WT) control APP/PS1 (on a C57BL/6J background) and 5xFAD (on a C57/SJL background) mice. At the conclusion of operant testing, auditory brainstem response (ABR) measures were taken on the same subjects to determine if evoked potentials provided accurate estimates of perceptual abilities. Behavioral detection worsened significantly across the lifespan in APP/PS1 mice, but there were no differences between mutant and WT mice. For 5xFAD mice, behavioral thresholds generally worsened over the lifespan but with substantial variability, which may be explained by genetic heterogeneity among the background strain. There were no differences between 5xFAD mutant and WT mice. ABR hearing threshold estimates generally matched behavioral findings, with APP/PS1 having significantly worse thresholds than 5xFAD mice but no within-model differences between mutants and WTs. The within-subject differences between behavioral and ABR thresholds ranged from <1 dB to over 40 dB across subjects, suggesting physiological measurements of auditory function are not necessarily reflective of an animal's acoustic perception.

Salivation supports oral health, taste sensation, swallowing, and digestion, but the brain mechanisms that regulate this process remain largely unknown. Here, we identify a salivatory center in the mouse brain stem that integrates sensory and learned anticipatory signals to control salivation. We show that activating choline acetyltransferase-expressing neurons in the inferior salivatory nucleus (IS) is sufficient to trigger saliva secretion. Using fiber photometry, we monitor real-time IS neural responses to mechanosensory and gustatory stimulation and find tight correlation with salivatory output. We further demonstrate that IS neurons receive input from local brain stem circuits, mediating rapid hardwired responses to taste, as well as direct cortical projections. Notably, gustatory cortex input is required for salivatory responses to predictive sensory cues in a Pavlovian conditioning paradigm. Together, our findings define the circuit underlying taste-evoked and anticipatory salivation and provide a foundation for dissecting this autonomic response in health and disease.

The lateral preoptic area (LPO) is a functionally heterogeneous hypothalamic structure that is increasingly recognised for its role in motivated and drug‐seeking behaviours. Although prior studies have shown that LPO neurons exhibit diverse activity patterns during cocaine self‐administration, the specific contributions of glutamatergic and GABAergic populations to conditioned responses to cocaine remain unclear. In this study, we recorded the activity of LPO glutamatergic ( vglut2 ‐expressing) and GABAergic ( vgat ‐expressing) neuronal subpopulations during cocaine conditioning to identify how these cell types respond to drug‐associated cues in awake, behaving mice. Our results revealed that, after cocaine conditioning, both glutamatergic and GABAergic populations showed reduced activity upon entry into the cocaine‐paired chamber. However, only glutamatergic neurons exhibited increased activity when mice entered the saline‐paired chamber. The magnitude of these activity changes was also correlated with behavioural outcomes: reduced GABAergic activity was associated with greater preference for the cocaine‐paired chamber, whereas stronger glutamatergic responses were associated with greater preference for the saline‐paired chamber. These findings indicate that LPO GABAergic and glutamatergic neurons exhibit distinct, cell type–specific patterns during cocaine‐conditioned place preference. Rather than indicating opposing motivational states, the results highlight that LPO activity relates to conditioned behaviours in a cell type– and context‐dependent manner. By linking activity in glutamatergic and GABAergic neurons with conditioned responses, this work provides initial evidence for how LPO circuits may contribute to drug‐associated learning.

Spinal cord injury (SCI) remains a debilitating neurological disorder with limited therapeutic options, as existing treatments primarily address symptoms rather than address the complex interplay of cellular and molecular barriers to regeneration. These barriers collectively hinder functional recovery, including inhibitory glial scarring, chronic neuroinflammation, intrinsic neuronal regenerative deficits, and disruption of the blood-spinal cord barrier (BSCB). To address these limitations, we developed NanoScript-PTEN (NS-PTEN), a nonviral nanoparticle platform that delivers synthetic transcription factors to transiently suppress phosphatase and tensin homolog (PTEN) expression. PTEN negatively regulates the PI3K/AKT/mTOR signaling axis, which is a critical determinant of neuronal survival and axonal growth. By reducing PTEN levels, NS-PTEN derepresses this pro-survival pathway, promoting neuronal regeneration in the injured spinal cord. By integrating a DNA-binding domain targeting the PTEN promoter, a transcriptional repression module, and a nuclear localization signal onto a gold nanoparticle (AuNP) scaffold, NS-PTEN achieves transient control over PTEN repression, reactivating pro-regenerative signaling while minimizing the risks of tumorigenesis associated with permanent gene silencing. In a clinically relevant contusion SCI rat model, NS-PTEN induced a coordinated series of structural and microenvironmental improvements that collectively support spinal cord repair. Histologically, NS-PTEN enhanced axonal continuity and remyelination, as evidenced by denser NF-positive fibers and substantially greater MBP preservation than in both the injury and AuNP groups. Concurrently, NS-PTEN markedly attenuated astroglial and microglial reactivity, reducing GFAP+ border formation and diminishing Iba1+ inflammatory cell accumulation. At the vascular interface, NS-PTEN upregulated CD31 and occludin expression, indicating restored endothelial integrity and the reconstruction of tight junctions, which are critical for BSCB repair. In parallel, the inflammatory milieu shifted toward a regenerative phenotype, characterized by suppressed pro-inflammatory cytokine expression (IL-6, TNF-α, and iNOS) and elevated anti-inflammatory/neurotrophic factors (IL-10 and BDNF). These improvements are consistent with secondary, microenvironment-level benefits arising from acute neuronal PTEN repression rather than direct modification of non-neuronal cell types. Importantly, PTEN expression partially rebounded by DPI-28, aligning with the intended transient activity window of the nanoscript system and supporting its translational safety. Through this combination of precise, nonintegrative gene modulation and broad downstream remodeling, NS-PTEN addresses both intrinsic neuronal limitations and extrinsic inhibitory features of the SCI microenvironment.