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Search indexed bioRxiv preprints in genomics, neuroscience, cell biology and bioinformatics. Read source abstracts and check manuscript versions; preprints are not peer reviewed.

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bioRxiv2026

Sport expertise and motor imagery abilities shape sensorimotor rhythm modulations during visualisation tasks: Implications for neurofeedback-based cognitive training in athletes

Kinaesthetic motor imagery (kMI) is widely used in sport to enhance motor performance by engaging cortical sensorimotor networks. Neurofeedback may further support kMI, but the optimal neural target to reinforce remains unclear. Maximal sensorimotor event-related desynchronisation (SMR-ERD) represents a relevant target as it may index sensorimotor cortex engagement, yet sport expertise has been associated with reduced SMR-ERD, potentially reflecting neural efficiency. The optimal neurofeedback target may therefore depend on sport expertise, movement expertise, and individual kMI ability. This study examined how these factors influence sensorimotor activity during kMI. We compared 17 basketball players (Experts) and 16 individuals without formal basketball training (Novices). kMI ability and frequency of use were assessed using questionnaires, while SMR-ERD was quantified using electroencephalography (EEG) during kMI. Participants imagined either a basketball-specific movement (Free throw), for which only Experts had extensive experience, or a generic movement (Box lifting), familiar to both groups. Experts reported greater kMI ability and more frequent kMI use than Novices. Only Experts exhibited significant and sustained SMR-ERD during kMI. Moreover, SMR-ERD was stronger in Experts than Novices specifically during Free throw kMI, corresponding to their movement of expertise. Nonetheless, within the Expert group, higher kMI ability was associated with reduced SMR-ERD. These findings suggest that sport expertise initially enhances voluntary recruitment of sensorimotor networks during kMI, whereas greater kMI ability may subsequently promote neural efficiency, resulting in reduced overall sensorimotor cortical activation. These results highlight the need to tailor kMI-based neurofeedback training to users' sport expertise and kMI ability levels.

neuroscience↗

bioRxiv2026

Entorhinal grid coding as a functional link between tau accumulation and episodic memory in human aging

Episodic memory decline is a common feature of cognitively normal aging, but its extent varies markedly across individuals. Although entorhinal tau pathology is thought to be a key contributor to episodic memory impairment, the neural mechanisms linking early tau accumulation to memory differences remain unclear. Grid-cell computations in the entorhinal cortex, which provide scaffolds for organizing experiences into episodic memories, offer one candidate mechanism. Here, we combined virtual-reality functional MRI, multivariate analysis, tau PET, and delayed word-list recall in cognitively normal older adults to test whether tau-related alterations in entorhinal coding are associated with worse episodic memory. Weaker left entorhinal grid-cell-like signal was associated with poorer memory performance, and individuals with higher left entorhinal tau burden showed weaker grid-cell-like signal. This association was specific to the canonical six-fold signal and was not explained by entorhinal volume, mean diffusivity, or intracortical myelination. A cross-sectional Bayesian mediation analysis further demonstrated that bilateral medial temporal tau burden is related to memory indirectly through left entorhinal grid-cell-like signal. Together, these findings provide evidence that entorhinal grid codes may constitute a functional pathway linking tau accumulation to memory variability in normal aging.

neuroscience↗

bioRxiv2026

Dendritic hotspots support switching between competing rules without expanding the cortical engram

Adaptive behavior requires updating responses when contingencies change while preserving prior associations and the capacity to learn a new. How this trade-off is resolved remains unknown. Here, we combined in vivo imaging of apical tuft spines in the secondary motor cortex (M2) with biologically constrained network modeling in mice performing a cross-modal rule-switch task. M2 inactivation impaired rule-switching but not learning or maintenance, identifying it as a conflict resolution substrate. Adaptation was accompanied by elevated spine turnover concentrated within stable dendritic hotspots, in which the formation, elimination and clustering of new spines were coupled and pre-existing spines were lost early. A network model reproduces these dynamics and predicts that dendritic hotspots are critical for resource-efficient adaptation. Within these reusable domains, spines encoding the prior rule are replaced by newly-relevant ones via sharing of plasticity-related resources. Preventing reuse increases both the plasticity and the engram size requirements to encode the two rules. We propose that dendritic hotspots provide a mechanistic substrate for efficient adaptive learning.

neuroscience↗

bioRxiv2026

Long-term mitigation of the foreign-body response with dexamethasone-eluting cochlear implants in mice

The inflammatory foreign body response that follows cochlear implantation produces intracochlear fibrosis, neo-ossification, and elevated electrode impedances that can compromise implant performance. Dexamethasone-eluting cochlear implants reduce this response, but the durability of their anti-inflammatory effect over long implantation intervals has not been established. Using a murine model of chronic cochlear implantation in CX3CR1+/eGFP Thy1+/eYFP dual-reporter mice, we compared dexamethasone-eluting and standard mouse cochlear implants at 224 and 336 days post-implantation. Density of CX3CR1+ macrophages, MHCII+CX3CR1+ antigen-presenting macrophages, -SMA+ fibrosis, and neo-ossification were quantified in the scala tympani, Rosenthal canal, and lateral wall of the basal turn. Standard implants produced persistent macrophage and antigen-presenting macrophage infiltration, accompanied by an -SMA+ fibrotic response and neo-ossification. Dexamethasone-eluting implants suppressed macrophage infiltration in all three regions out to 336 days and reduced fibrosis at 224 days. In the subset of cochleae with electrode array translocation, dexamethasone-eluting implants attenuated macrophage infiltration and confined the fibrotic and osseous response to the site of translocation, whereas standard implants produced a widespread response. A reduction in immune cell density was also observed in the contralateral, unimplanted cochleae of animals implanted with dexamethasone-eluting implants, suggesting a wider component to the drug's effect. Dexamethasone-eluting cochlear implants therefore provide sustained, long-term suppression of the cochlear foreign body response in mice, supporting their continued translation toward clinical application. This effect was associated with continued low-level dexamethasone elution out to 336 days post-implantation; further work is needed to assess the durability of this effect at the conclusion of drug elution.

neuroscience↗

bioRxiv2026

Cross-Kingdom Control: Yeast Prion Protein Modulates Host Physiology in Drosophila

Prions, once mainly studied for their pathogenic roles, are now gaining recognition as adaptive elements in microbial physiology. Over one-third of wild yeast isolates harbor prion proteins, yet their impact on host-microbe interactions remains poorly characterized. Given the ecological dominance of yeasts in the Drosophila mycobiome, we leveraged the Drosophila melanogaster-Saccharomyces cerevisiae system to investigate how the mycobiome-derived prion, [MRPL10+], modulates host physiology. We show that flies exposed to [MRPL10+] yeast exhibit significantly enhanced cold tolerance and increased locomotor activity. This effect persists with heat-killed yeast and diluted culture, suggesting a stable, potent bioactive factor. Using the genetically diverse Drosophila Global Diversity Lines (GDL), we identified natural variation in responsiveness to [MRPL10+] yeast. Genome-wide association and functional RNAi screening revealed a gut-brain signaling axis involving genes critical for digestion, intercellular communication, transcription regulation, and neural transmission. Notably, serotonin and octopamine pathways were essential for [MRPL10+]-induced changes in cold tolerance and locomotion, implicating neuromodulatory circuits in prion-mediated microbial signaling. Our findings establish a mechanistic link between a fungal prion and host metabolic and neural adaptation. This work provides the first genetic dissection of a prion-mediated host-microbe interaction, laying the groundwork for investigating beneficial prions in complex microbial communities and highlighting a new dimension of the mycobiomes influence on animal physiology.

evolutionary biology↗

bioRxiv2026

Preserved brain hierarchy supports residual vision without awareness after visual cortex damage

Damage to the primary visual cortex causes loss of conscious vision, yet some patients retain the ability to respond to stimuli despite reporting no visual experience. Why similar lesions produce such different behavioral phenotypes remains unclear. While research to date has focused primarily on spared pathways that bypass V1, here we asked whether these divergent outcomes are also linked to the brain's intrinsic functional architecture. In the largest resting-state fMRI cohort of patients with unilateral V1 damage reported to date, we quantified information sharing between regions across cortical and subcortical parcels in blindsight-positive and blindsight-negative patients, as well as in age-matched healthy controls. Despite comparable lesions, the two patient groups displayed distinct hierarchical patterns on the cortex: B+ patients preserved a sensory-to-association organization as in healthy controls, whereas B- patients exhibited a marked flattening of this hierarchy. The effect was driven by abnormally low shared-information coupling within unimodal cortices and scaled continuously with single-subject behavioral blind-field detection performance. A thalamic region consistent with the pulvinar, linking the contralesional visual cortex and the frontal eye field, discriminated B+ from B- patients. These findings highlight the system-level consequences of V1 damage supporting blindsight, suggesting that the unimodal-transmodal axis might track not only global states of consciousness, but also whether sensory information can guide behavior without awareness.

neuroscience↗

bioRxiv2026

Copulation calls indicate fertility but do not reflect female mate competition in wild Guinea baboons

Across different modalities, signals play a core role in attracting mates and influencing mating success. In several non-human primate species, females produce calls during mating that are thought to promote male competition over receptive females. The extent to which social system characteristics modulate the function of copulation calls remains less clear. We studied copulation calls in wild Guinea baboons (Papio papio), who live in a multilevel society structured around units in which females associate and mate almost exclusively with a single male. We hypothesised that females use copulation calls as an indirect form of mate competition, with competition increasing in larger units. In addition, we hypothesised that females are more likely to mate again after calling. We analysed 6116 copulations between 2014 and 2025, involving 99 reproductively active females and 78 subadult and adult males. Females produced copulation calls in 72.7% of copulations, with large inter-individual variation. Neither unit size nor its interaction with the female's swelling size or the presence of simultaneously receptive females affected the probability of calling. A survival analysis with a subset of the data (2353 copulations) revealed no effect of calling on the latency to the next mating. Our results render the hypothesis that female Guinea baboons use calls in indirect mate competition unlikely. Yet, the probability of calling varied with sexual swelling size, suggesting that calls signal female fertility. Possibly, Guinea baboon copulation calls represent an evolutionary remnant, no longer under selective pressure, and can be considered index signals of female fertility.

animal behavior and cognition↗

bioRxiv2026

Characterization and pharmacological modulation of Alzheimers disease-associated human microglial states

Microglia are central mediators of Alzheimers disease (AD) pathogenesis, yet the mechanisms driving disease-associated microglial states and their therapeutic modulation remain poorly understood. Here, we integrated single-nucleus transcriptomic datasets across the AD spectrum and identified disease- and lipid-associated microglia (DLaM) as a major AD-enriched population linked to genetic risk, neuropathology and cognitive decline. To model this state experimentally, we screened AD-relevant perturbations in human induced pluripotent stem cell (hiPSC)-derived microglia and found that ferric ammonium citrate (FAC) reproducibly induced a DLaM-like state characterized by lipid accumulation, lysosomal dysfunction and impaired A{beta} phagocytosis. Using a transcriptomics-based state-reversion screen, we identified LY2090314 as a potent modulator that restored microglial function and induced a distinct lysosomal-metabolic state. These findings establish a framework for transcriptomic disease-state-guided therapeutic discovery in AD.

neuroscience↗

bioRxiv2026

The pursuit of motivational goals reduces pain through an opioidergic mechanism

Pain promotes protective behavior but can interfere with other biologically important goals. Survival may require overcoming pain to obtain rewards, secure resources or escape danger, yet evidence for pain modulation by competing demands and endogenous modulatory systems during goal pursuit is lacking. We developed a paradigm in which participants chose whether to pursue monetary rewards despite painful heat stimulation during fMRI, under placebo or opioid receptor blockade with naloxone. Actively pursuing motivational goals during painful stimulation reduced perceived pain and increased fMRI signal in pain-modulatory cortical regions, including multiple subregions of the rostral anterior cingulate cortex (rACC) and dorsolateral prefrontal cortex, alongside enhanced rACC-periaqueductal gray coupling, consistent with recruitment of the descending pain modulatory system. Behavioral and neural effects were attenuated by naloxone, supporting a mediating role for endogenous opioids. These findings provide convergent evidence that active goal pursuit engages opioidergic pain modulatory mechanisms to reduce pain in humans.

neuroscience↗

bioRxiv2026

Evolution and Human Neural Individuality

Individuality is a defining feature of human biology. The functional network architecture of the human brain harbors person-specific qualities and forms individualized connectivity profiles that function as a neural fingerprint, both stable and unique across time. Here, using fMRI data from 431 Human Connectome Project participants, we examined whether neural individuality is more strongly exhibited in brain regions bearing signatures of recent human evolution. We calculated region-wise fingerprinting accuracy and associated it with four properties of evolutionary cortical organization: cortical expansion, myelin content estimate (T1w/T2w), human-specific gene-expression profiles, and functional homology to other primates. Across all four measures, neural individuality was strongest in cortical areas showing greater evolutionary novelty in humans, particularly frontoparietal control and default mode networks, and weaker in more conserved primary regions. Our findings connect evolutionary variation across species with stable functional variation among individuals.

neuroscience↗

bioRxiv2026

Stronger brain responses to acute stress reflect greater everyday stress variability

Laboratory stress tasks are widely used to assess individual differences in acute stress reactivity, yet it remains unclear how these responses correspond to stress experienced in everyday life. Here, we combined the Montreal imaging stress task (MIST) with ecological momentary assessment (EMA) over three months to assess acute and everyday stress in 67 healthy women. Greater within-person variability in everyday stress, but not average stress levels, were associated with stronger overall stress-related brain responses (b = 0.73, p = .039), with a whole-brain association particularly evident in the bilateral caudate (rROI = .32, pcluster.FWE < .001). Greater everyday stress variability was also associated with stronger stress-related functional connectivity between the ventromedial prefrontal cortex (vmPFC) and parietal and posterior medial regions (pcluster.FWE < .001). We conclude that acute neural stress responses relate more closely to fluctuations in perceived stress than to how stressed an individual feels on average. This suggests that laboratory stress tasks capture acute stress responsivity that is distinct from average stress exposure, highlighting the importance of considering what these tasks measure when interpreting individual differences in acute stress responses.

neuroscience↗

bioRxiv2026

Time-averaged and Time-varying Structure of the Gastric Network Revealed Through fMRI-Electrogastrogram Synchronization

The gastric network, comprised of brain regions whose activity synchronizes with the stomach's slow-wave rhythm, offers a unique window into the brain-body interaction involved in interoceptive processing. While previous work has established the existence of this network, its intrinsic organization and temporal unfolding remain poorly understood. Here, we reanalyzed resting-state fMRI-electrogastrogram data from 43 healthy adults of both sexes to characterize the time-averaged architecture and time-varying reconfiguration of the gastric network. We identified regions exhibiting phase-locked synchronization with the stomach slow electrical rhythm (0.05 Hz) and characterized cortical parcels comprising this network. Time-averaged graph-theoretical analysis revealed a fixed unimodal organization of functional communities, with primary visual, default mode network (DMN) and dorsal attention regions emerging as the principal time-averaged hubs. Next, we applied edge-centric functional connectivity (eFC) to capture the network state during transient high-amplitude "bursts". Time-varying community detection revealed communities whose compositions formed integrative combinations of DMN, visual, attentional and control elements. Edge-derived hubs shifted away from primary visual dominancy in the time-averaged analysis, and were instead directed by DMN regions, suggesting that moments of heightened connectivity in the network are coordinated by multisensory integration rather than passive sensory processing. These findings demonstrate that the gastric network is not merely a time-averaged, sensory-bound system, but rather a flexible and dynamically reconfiguring interoceptive network whose organization is selectively coordinated by transient cofluctuation events. This work provides a comprehensive network analysis of gastric-brain coupling and reveals a temporally structured mode of interoceptive integration that may support adaptive physiological and cognitive regulation.

neuroscience↗

bioRxiv2026

Detection of Frustration-related Operant Behavior in Rats via Machine Learning Methods

Despite its strong link to neuropsychiatric conditions, frustration remains critically understudied in humans and animals alike. Therefore, there is an urgent need to develop tools to understand and therapeutically target frustration-related functions. Interestingly, humans and rats respond similarly during frustrative nonreward by increasing barpress durations. We previously validated barpress duration in rat operant tasks as a reliable measure of frustration-related behavior; however, it is wellknown that in addition to duration of responding, emotional states such as frustration alter other aspects of responding such as force of pressing. One-dimensional, static measures such as maximum force could miss rich information contained within operant data. Thus, the objective of this study is to apply machine learning (ML) to force/time profiles to discriminate frustration-related barpresses from non-frustration-related barpresses. Results showed an AUROC for FR1 (i.e., non-frustrated) vs. extinction (frustrated condition) for individual barpresses of 0.65 that improved to 0.84 with a chunk size of 10. The model generalized well to progressive ratio responding, a different kind of frustration procedure. We conclude that force/time profiling does provide utility beyond one dimensional measures of duration or force separately, meaning that we can indeed infer the internal state of frustration from behavior using ML techniques. Importantly, this project will also serve as proof-of-concept for applying ML to predict other internal states from barpress data.

animal behavior and cognition↗

bioRxiv2026

PathFold: Predicting the Entire Protein Folding Pathway from Protein Sequence Alone

Recent advances in protein structure prediction, exemplified by AlphaFold, have largely addressed the determination of static structures, one aspect of the protein folding problem. However, predicting folding pathways, by which proteins reach their native states, remains a significant challenge. Here, we present PathFold, a deep learning framework that predicts protein folding pathways directly from sequence information. PathFold leverages an AlphaFold-based module to extract structural information from the sequence and generates a progressive folding trajectory from an extended conformation using a diffusion model. By modeling the full trajectory, it enables prediction of folding intermediates and transition pathways, analogous to those observed in steered molecular dynamics (SMD) simulations. The predicted pathways reveal well-defined intermediates and sequential folding events, and show agreement with experimental folding data, including measured {Phi}-values.

bioinformatics↗

bioRxiv2026

Profiling and modulating astrocyte borders at injected biomaterials in mice

Astrocyte border formation is a conserved neuroprotective response to neural tissue disruption, yet astrocyte border states at implanted biomaterials remain less well characterized than injury responses. Here, we developed the Astrocyte Border Characterization (ABC) Tool, which leverages a shear-thinning, injectable biomaterial to locally deliver astrocyte-specific RiboTag AAVs and small molecule regulators in the mouse striatum, enabling molecular profiling and phenotypic modulation of astrocyte border (AB) cells. Spatially precise delivery of AAV using the ABC Tool yielded enhanced specificity and robust RiboTag expression in AB cells from 7-70 days post injection. Temporal transcriptomic profiling of AB cells revealed predominantly acute, transient changes in genes governing dedifferentiation, proliferation, metabolic reprogramming, and inflammation regulation. Persistent changes accounted for only 14% of regulated genes but involved critical gain of functions in immune regulation and host defense that mirrored astrocyte border responses at chronic CNS injuries. Local delivery of indiscriminate or astrocyte-selective ablation molecules delayed, rather than prevented, border formation, ultimately yielding thicker astrocytes borders with increased inflammation and fibrosis at the biomaterial-tissue interface. Conversely, local delivery of {beta}-hydroxybutyrate (BHB) from the ABC Tool altered key aspects of the transcriptional reprogramming to attenuate chronic astrocyte reactivity and prevent biomaterial contraction without exacerbating inflammation or fibrosis. Our findings establish the ABC Tool as a bioassay for studying and manipulating astrocyte borders at implanted biomaterials and identify focal metabolic regulation as a strategy to modulate AB cell phenotypes and enhance the CNS biocompatibility of biomaterials.

neuroscience↗

bioRxiv2026

Test-Retest Reliability of Motor Evoked Potentials Across Eight Bilateral Lower-Limb Muscles

Objectives: Transcranial magnetic stimulation (TMS) is widely used to probe corticospinal excitability by eliciting motor evoked potential (MEP)s in targeted muscles, with MEP characteristics such as magnitude and latency reflecting the physiological state of the pathways being stimulated. Although numerous studies have examined MEP reliability in upper extremity muscles, less is known about the reliability of this measurement across the lower extremity. We hypothesized that inter-session, test-retest reliability of MEPs recorded simultaneously from multiple lower-limb muscles, from a single TMS location, would differ by muscle, stimulation intensity, and quantification method. Materials and Methods: Ten healthy participants (5 males, 5 females) completed three TMS sessions separated by atleast one week. At each session, the stimulation hotspot was identified using a five-location virtual grid anchored at the vertex, with electromyography (EMG) recorded from all eight muscles of interest at each grid location; the grid location producing the largest and most consistent MEPs in the tibialis anterior (TA), the primary target muscle, was selected as the stimulation site and held constant across all three sessions. MEPs were then recorded bilaterally from the TA, soleus, rectus femoris, and biceps femoris muscles at two stimulation intensities (110% and 120% resting motor threshold (RMT)). MEP size was quantified using mean rectified magnitude and peak-to-peak amplitude, and inter-session reliability was assessed using intraclass correlation coefficients (ICC). Bland-Altman analysis was used to characterize the range of measurement variability across all eight muscles. Results: MEP size differed across sessions, and reliability varied by muscle, intensity, and quantification method. The highest reliability was observed in the right TA, the muscle used to establish the stimulation hotspot, using mean rectified magnitude at 120% RMT. Reliability was comparatively lower in the seven non-target muscles recorded from the same fixed stimulation site, indicating that MEP consistency was not uniform across the lower-limb musculature. Conclusions: MEP reliability in the lower extremity depends heavily on the muscle, stimulation intensity, and quantification method used, and is highest in the muscle for which the stimulation site was optimized. These findings support the interpretation that coil positioning targeted to a specific muscle yields more consistent responses in that muscle than in others recorded from the same fixed site, and underscore the importance of careful muscle selection and hotspot optimization when designing TMS protocols for longitudinal or clinical lower-limb research.

neuroscience↗

bioRxiv2026

Multidimensional diffusion MRI reveals heterogeneous microstructural remodeling associated with amyloid pathology

Alzheimer's disease (AD) pathology involves amyloid deposition, reactive gliosis, and localized tissue alterations that coexist within the same brain regions, creating heterogeneous microstructural environments within individual imaging voxels. Conventional diffusion MRI averages these environments into aggregate measures, potentially obscuring their distinct contributions. Frequency-dependent multidimensional MRI ({omega}MD-MRI) resolves distributions of water components with different diffusion length scales, anisotropies, and relaxation properties, providing sensitivity to microstructural restriction, heterogeneity, and shape-size correlations within a voxel. Whether these measurements reveal microstructural complexity associated with AD pathology remains unclear. Here, we performed {omega}MD-MRI on ex vivo brain specimens from approximately 8-month-old 5xFAD and wild-type mice and interpreted the imaging findings alongside complementary histology. {omega}MD-MRI revealed widespread but spatially nonuniform differences between 5xFAD and wild-type brains. Measurements sensitive to microstructural restriction, heterogeneity, and shape-size correlations consistently indicated greater microstructural heterogeneity in 5xFAD brains, with the most prominent differences in the hippocampal formation and major cerebral white matter tracts. Complementary qualitative histology demonstrated extensive amyloid deposition and glial activation in affected regions, while overall cytoarchitecture and myelin organization remained largely preserved. Thus, the {omega}MD-MRI abnormalities occurred in tissue characterized by multiple coexisting pathological and relatively preserved microstructural environments rather than widespread structural degeneration. These findings demonstrate that {omega}MD-MRI can reveal the spatial and microstructural heterogeneity associated with amyloid pathology and provide a more comprehensive characterization of AD-related tissue alterations.

neuroscience↗

bioRxiv2026

Development and pharmacological evaluation of an intranasal liposomal norbinaltorphimine formulation for the prevention of pain-induced negative affect

Chronic pain is frequently accompanied by negative affect and motivational deficits due to dysregulated mesocorticolimbic dopamine and kappa opioid receptor (KOR) signalling. Although intracranial KOR antagonism prevents pain-induced negative affect in preclinical models, systemic KOR antagonists can produce adverse off-target effects in the periphery, thereby limiting its clinical utility. Consistent with this, we found that systemic administration of KOR antagonist norbinaltorphimine (NorBNI), exacerbated motivational deficits in rats with persistent inflammatory pain. We hypothesized that maximizing central and minimizing peripheral KOR antagonism could overcome these limitations. To test this, we engineered an intranasal liposomal NorBNI formulation incorporated into an in-situ forming mucoadhesive hydrogel to enable selective nose-to-brain delivery (Nor-BNILV-HG). We characterized its physicochemical properties and functional efficacy in rats with inflammatory pain produced by Complete Freund's Adjuvant (CFA). NorBNI-loaded liposomes exhibited high drug entrapment efficiency, nanometric size, and suitable surface charge for intranasal administration. The selected thermosensitive hydrogel demonstrated appropriate gelation properties and sustained drug release. Intranasal administration of NorBNI-LV-HG produced negligible systemic NorBNI levels compared with intraperitoneal delivery. In vivo microdialysis showed that NorBNI-LV-HG prevented KOR agonist-induced reductions in nucleus accumbens (NAc) dopamine release, confirming functional central KOR blockade. Behaviourally, intranasal NorBNI-LV-HG attenuated pain-induced impairments in sucrose motivation. Importantly, unlike systemic NorBNI, repeated intranasal NorBNI-LV-HG did not alter mechanical nociceptive thresholds in pain-naive animals, suggesting this strategy mitigates unwanted peripheral nociceptive effects. Together, these findings demonstrate that intranasal NorBNI-LV-HG achieves functional brain KOR antagonism while minimizing systemic exposure and off-target effects. Selective nose-to-brain delivery of KOR antagonists therefore represents a promising therapeutic strategy to prevent and potentially reverse the affective and motivational consequences of pain and may overcome key translational barriers associated with systemic KOR treatments.

neuroscience↗