bioRxiv Subject Collection: Neuroscience's Journal

An active Unc13A is Reboundless in sleep homeostasis
One of the major characteristics of sleep is homeostatic sleep rebound following sleep loss. While the molecular mechanisms of baseline sleep regulation have been intensively studied, a specific molecular understanding of sleep rebound remains elusive. Here, we show that a constitutively active form of the Munc13-family presynaptic release factor Unc13A, which lacks the inhibitory Ca2+/calmodulin interaction domain (Unc13AWRWR), dominantly suppressed sleep rebound upon acute sleep deprivation, leading to a nearly complete elimination of recovery sleep (''reboundless''). In contrast, baseline sleep remained largely normal. Through a genetic modifier screen, we found that this dominant ''reboundless'' phenotype of Unc13AWRWR was rescued by a partial loss of Snap, a cofactor of NSF required for disassembly and recycling of post-fusion cis-SNARE complex. Given that Unc13A promotes fusion-competent trans-SNARE complex formation, these findings suggest that sleep rebound may depend on a delicate balance between SNARE complex assembly and recycling. Additionally, we found that expression of a human disease-associated active Unc13A (Unc13APL) variant attenuated baseline and rebound sleep. Since both Unc13AWRWR and Unc13APL were shown to promote presynaptic release probability (Pr), we speculate that Unc13A suppresses recovery sleep likely by increasing Pr and subsequently enhancing synaptic transmission, probably through elevated trans-SNARE formation and efficient cis-SNARE recycling. Taken together, our data demonstrate a fundamental role of Unc13A and SNARE dynamics in sleep homeostasis.

Large sharp-wave ripples promote hippocampo-cortical memory reactivation and consolidation
During sleep, ensemble activity patterns encoding recent experiences are reactivated in the hippocampus and cortex. This reactivation is coordinated by hippocampal sharp-wave ripples (SWRs) and is believed to support the early stages of memory consolidation. However, only a minority of sleep SWRs are associated with memory reactivation in the hippocampus and its downstream areas. Whether that subset of SWRs have specific physiological characteristics and directly contribute to memory performance is not known. We identified a specific subset of large SWRs linked to memory reactivation in both the hippocampus and prefrontal cortex (PFC) of mice, and found that their occurrence selectively increased during sleep following new learning. Closed-loop optogenetic SWR boosting during sleep was sufficient to enhance ensemble memory reactivation in hippocampus and PFC. This manipulation also improved subsequent memory retrieval and hippocampal-PFC coordination, causally linking both phenomena to SWR-associated ensemble reactivation during sleep.

Mycobacterium tuberculosis sulfolipid-1 (Sl-1) increases the excitability of mouse and human TRPV1-positive sensory neurons in a YM254890-reversible fashion
Cough is a hallmark sign of tuberculosis and key driver of transmission. While traditionally attributed to host-driven inflammation, we previously demonstrated that Mycobacterium tuberculosis lipid extract (Mtb extract) and its component sulfolipid-1 (SL-1) directly activate nociceptive neurons to induce cough in guinea pigs. However, the cellular mechanisms by which Mtb extract and SL-1 modulate nociceptive sensory neurons remain incompletely understood. Here, we show that Mtb extract enhances action potential (AP) generation in mouse nodose nociceptors via an SL-1-dependent mechanism. Using calcium imaging, we found that Mtb extract and SL-1 increased intracellular calcium; signals in TRPV1-positive; neurons from both mouse nodose and human dorsal root ganglia (hDRG). These calcium; signals were attenuated by the Galpha;q/11 pathway inhibitor YM254890, even in the absence of extracellular calcium;, suggesting involvement of intracellular calcium; stores. Together, these findings indicate that SL-1 engages Galphaq/11 coupled pathways to sensitize nociceptors via intracellular calcium release, providing mechanistic insight into tuberculosis-associated cough and potential targets for therapeutic intervention.

Precision Neuromodulation with Real-Time Brain Decoding for Working Memory Enhancement
Transcranial magnetic stimulation (TMS) has transformed non-invasive brain therapies but faces challenges due to variability in outcomes, likely stemming from inter-individual differences in brain function. This study aimed to address this challenge by integrating personalized functional networks (PFNs) derived from functional magnetic resonance imaging (fMRI) with a neural network-based decoder to optimize stimulation in real time during a working memory (WM) task. After identification of individualized stimulation targets, participants completed a TMS/fMRI session, performing a WM task while receiving rTMS at randomized frequencies. Decoder outputs and behavioral data during this session guided selection of optimal and suboptimal stimulation frequencies. Participants then underwent six stimulation sessions (three optimal, three suboptimal) in a randomized crossover design, performing WM and control tasks. The optimal stimulation improved WM performance by the final session, with no improvement observed in the control task. Additionally, the decoder output predicted behavioral performance on the WM task, both during the TMS/fMRI and neuromodulation sessions. These findings show that neural network-guided closed-loop neuromodulation can improve TMS effectiveness, marking a step forward in personalized brain stimulation.

A single binge ethanol exposure is apoptotic within hours across neurodevelopment and partially regulated by the Myt1l gene.
Ethanol rapidly produces widespread neuronal apoptosis during early development, but this susceptibility declines as the brain matures. In previous research, we found Myt1l (a proneuronal transcription factor) mutations can cause precocious differentiation, neuronal immaturity, and transcriptomic alterations, including many in apoptotic regulators. Therefore, we used a recently developed Myt1l haploinsufficient mouse model to examine this gene's effects on ethanol-induced apoptosis across different developmental stages. We discovered that haploinsufficiency can moderately influence vulnerability to ethanol in a complex, age- and cell type-specific manner: apoptosis was reduced on P7, increased P21, but unaffected on P60. Remarkably, we also discovered the previously unrecognized ability of a single binge of ethanol to rapidly increase apoptosis within six hours in early adolescent and adult wild-type mice occurring in microglia and the newborn granule neurons in the hippocampus. This suggests apoptosis is an underappreciated contributor to ethanol's neuropathology at older ages and, translated to human use, occurs far more frequently than previously recognized.

REACTIVATION PROTECTS HUMAN MOTOR MEMORIES AGAINST INTERFERENCE FROM COMPETING INPUTS
Many newly encoded memories are labile when acquired but then consolidate to more stable states. Reconsolidation theory posits that reactivating a consolidated memory again destabilizes it, increasing its vulnerability to interference from competing memories. In a series of 3-day experiments, we investigated the fate of a motor memory when it is reactivated and challenged with a competing one. We pursued a modular design in which humans adapted to a visuomotor rotation A (day 1), then an opposite rotation B (day 2), followed by a retest on A (day 3). We first found that reactivating A before learning B (A-AB-A) caused no greater impairment in A retention than non-reactivation (A-B-A). That is, while interference occurred, it appeared to be uninfluenced by reactivation, contradicting reconsolidation predictions. We then tested an alternate idea, that reactivation might serve to protect the original memory from interference. In subsequent experiments, we introduced no rotation (N) trials either prior to A relearning (A-AB-NA and A-B-NA groups), or immediately after B learning (A-ABN-A and A-BN-A groups). Here, we observed that reactivation served a protective function, but only when B was washed out immediately, preventing its consolidation (A-ABN-A group). Collectively, our results show that reactivation does not necessarily increase the susceptibility of a motor memory to interference but may rather shield it from degradation by competing learning. Our findings align with theories positing memory transitions between active and inactive states, and hold implications for strategies focused on improving memory retention in rehabilitation, sports and skills training.

Rod photoreceptors control the ON vs OFF polarity of cone-signaling neurons
A fundamental feature of the visual system is its ability to detect image contrast. The contrast processing starts in the first synapse of the retina where parallel pathways are established to compute contrast to bright (ON pathway) and dark (OFF pathway) objects, separately transferred to morphologically identified ON and OFF cells throughout the visual system. Here, we found that response polarity in ON and OFF neurons is not fixed but rather switches dynamically to the opposite sign. The switch was not observed in rod-knockout mice, indicating that rods generate the polarity switch. We determined that neither horizontal cells nor rod-signaling pathways were responsible for the switch. Instead, we discovered that EAAT5 glutamate transporters located at photoreceptor terminals were required to produce the polarity switch. Our findings provide a new perspective on the adaptive properties of neural networks and their ability to encode contrast across the visual dynamic range.

Photothrombotic Ischemic Thalamic Stroke in Mice Recapitulates Spontaneous Pain Features of Central Post-Stroke Pain in Humans
Central post-stroke pain (CPSP) is a highly distressing condition that develops in 50% of people who suffer a thalamic stroke, and is typically unresponsive to current clinical treatments. Hypoxic damage to the ventral posterolateral (VPL) and ventral posteromedial (VPM) sensory thalamic nuclei, in particular, precipitates CPSP. One barrier to developing treatments for CPSP is the lack of preclinical models of thalamic ischemic stroke. In this study, we present a novel mouse model of CPSP induced through targeted photothrombotic ischemia. After eliciting hypoxia in the sensory thalamus of male mice, we assessed pain behaviors over a four-week period. Stroke-affected mice exhibited a persistent spontaneous facial grimace from day four to week four post-stroke, indicative of pain. Hind-paw mechanical hypersensitivity indicative of altered nociception, characteristic of VPL and VPM hemorrhagic CPSP models, was not detected in our model. Immunofluorescence analysis revealed increased activated microglia (Iba1) and reactive astrocytes (GFAP). Iba1 fluorescence intensity in the VPL thalamus, but not the VPM thalamus, correlated with the severity of facial grimace at four weeks post-stroke. Clustering based on behavioral phenotypes identified a subpopulation of mice in which grimace pain spontaneously resolved, by four weeks post-stroke, relative to sham controls, suggesting that this model can be used to understand how stroke recovery may influence pain chronification. This model provides a valuable tool to investigate the cellular and circuit mechanisms underlying CPSP after an ischemic thalamic stroke.

Long-Term Effects of Adolescent 5F-MDMB-PICA Intravenous self-administration: Neurobehavioral Consequences and medial Prefrontal Cortex Dysfunction in Adult Mice
Background: Synthetic Cannabinoids Receptor Agonists (SCRAs) are the largest group of new psychoactive substances monitored worldwide. 5F-MDMB-PICA is a recent SCRA classified as a potent full agonist at CB1/CB2 receptors able to activate the mesolimbic dopamine (DA) transmission in adolescent but not in adult mice. Here, we have studied its reinforcing effects in adolescent mice and characterized the neurochemical and behavioral effects induced in the same animals in adulthood. Methods: We utilized an intravenous self-administration (IVSA) protocol in adolescent (PND 40-56) CD-1 male mice. In adulthood (PND 66-78), we conducted several behavioral and neurobiological assessments including: Sucrose Preference Test (SPT); Resident Intruder Test (RIT); Olfactory Reactivity Test (ORT); brain microdialysis to quantify DA levels in the medial Prefrontal Cortex (mPFC); and fiber photometry analysis using the GCaMP calcium sensor to monitor excitatory neural dynamics in the mPFC after exposure to an aversive odorant. Results: We found that 5F-MDMB-PICA, administered through IVSA in adolescent mice, produced an inverted U-shaped dose-response curve. The dose of 2.5 g/kg/25ul elicited behavior consistent with drug seeking. Adult mice exposed to 5F-MDMB-PICA during adolescence exhibited significant behavioral and neurochemical changes in adulthood compared to control mice. These behaviors included increased aggression, reduced social interaction, an anhedonic state, and an abolishment of mPFC DA response to an aversive odorant, as measured by in vivo brain microdialysis. Moreover, fiber photometry analysis of excitatory neuronal activity in the mPFC showed diminished calcium activity in response to the same aversive odorant in 5F-MDMB-PICA-exposed mice compared to controls. Conclusions: Notably, this study is the first to demonstrate that adolescent mice can acquire and sustain IVSA of 5F-MDMB-PICA. Furthermore, it highlights the long-term behavioral and neurochemical changes associated with adolescent exposure to 5F-MDMB-PICA, underscoring the potential detrimental effects of its use during this critical developmental period.

Simultaneous recording of spikes and calcium signals in odor-evoked responses of Drosophila antennal neurons
Most insects, including agricultural pests and disease vectors, rely on olfaction for key innate behaviors. Consequently, there is growing interest in studying insect olfaction to gain insights into odor-driven behavior and to support efforts in vector control. Calcium imaging using GCaMP fluorescence is widely used to identify olfactory receptor neurons (ORNs) responsive to ethologically relevant odors. However, accurate interpretation of GCaMP signals in the antenna requires understanding both response uniformity within an ORN population and how calcium signals relate to spike activity. To address this, we optimized a dual-modality recording method combining single-sensillum electrophysiology and widefield imaging for Drosophila ORNs. Calcium imaging showed that homotypic ab2A neurons exhibit similar odor sensitivity, consistent with spike recordings, indicating that a single ORN's response can reliably represent its homotypic counterparts. Furthermore, concurrent dual recordings revealed that peak calcium responses are linearly correlated with spike activity, regardless of imaging site (soma or dendrites), GCaMP variant, odorant, or fly age. These findings validate the use of somatic calcium signals as a reliable proxy for spike activity in fly ORNs and provide a foundation for future large-scale surveys of spike vs. calcium response relationships across diverse ORN types.

Motor Learning Outside the Body: Broad Skill Generalisation with an Extra Robotic Limb
Our ability to transfer motor skills across tools and contexts is what makes modern technology usable. The success of motor augmentation devices, such as supernumerary robotic limbs, hinges on users capacity for generalised motor performance.

We trained participants over seven days to use an extra robotic thumb (Third Thumb, Dani Clode Design), worn on the right hand and controlled via the toes. We tested whether motor learning was confined to the specific tasks and body parts involved in controlling and interacting with the Third Thumb, or whether it could generalise beyond them.

Participants showed broad skill generalisation across tasks, body postures, and even when either the Third Thumb or the controller was reassigned to a different body part, suggesting the development of abstract, body-independent motor representations.

Training also reduced cognitive demands and increased the sense of agency over the device. However, participants still preferred using their biological hand over the Third Thumb when given the option, suggesting that factors beyond motor skill generalisation, cognitive effort, and embodiment must be addressed to support the real-world adoption of such technologies.

Cortical dissociation of spatial reference frames during place navigation
Animals rely on both sensory perception and memory when navigating relative to learned allocentric locations. Incoming sensory stimuli, which arrive from an egocentric perspective, must be integrated into an allocentric reference frame to allow neural computations that direct an animal toward a learned goal. This egocentric-allocentric spatial transformation has been proposed to involve projections from the rodent postrhinal cortex (POR), which receives strong visual input, to the medial entorhinal cortex (MEC), which contains allocentric spatial cell types such as grid and border cells. A major step toward understanding this transformation is to identify how POR and MEC spatial representations differ during place navigation, which is currently unknown. To answer this question, we recorded single neurons from POR and MEC as rats engaged in a navigation task that required them to repeatedly visit a learned uncued allocentric location in an open field arena to receive a randomly scattered food reward. While neurons in both regions displayed strong tuning to the spatial structure of the environment, neither showed bias toward the goal location despite strongly biased behavior. Critically, when local visual landmarks were manipulated to place the visual scene in conflict with the learned location, POR neurons adjusted their tuning preferences to follow the visual landmarks, while MEC neurons remained in register with the true global reference frame. These findings reveal a strong dissociation between POR and MEC spatial reference frames during place navigation and raise questions regarding the mechanisms underlying integration of POR egocentric signals into the MEC allocentric spatial map.

The effects of gait speed on the responses to immediate and prolonged exposure to mediolateral optic flow perturbation in healthy young adults
BackgroundOptic flow is vital for locomotor control and is often perturbed to study the impact of optic flow on balance control. However, it remains unclear whether gait speed influences responses to such perturbations. This study aims to examine the effects of gait speed on gait parameters following immediate and prolonged exposure to mediolateral optic flow perturbations.

MethodsTwenty-one young adults (23.43 {+/-} 4.19 years) walked on an instrumented treadmill, including 3 phases: baseline (3 min), perturbation with mediolateral optic flow (8 min), and post-perturbation (3 min). Trials were conducted at 0.6, 1.2, and 1.8 m/s. Ground reaction forces and 3D motion data were collected to calculate mediolateral margin of stability (MoS), mean step length (SL), step width (SW) and their variabilities. Three repeated-measures ANOVAs (Speed by Phase) were used to compare: baseline vs. early perturbation, early vs. late perturbation, and baseline vs. post-perturbation.

ResultsThe responses to immediate and prolonged exposure to optic flow perturbation were speed dependent. Walking at slow speeds induced greater immediate responses in mediolateral gait parameters (SW and mediolateral MoS, both p < 0.001) compared to walking at faster speeds. During the perturbation phase, the adaptations were larger at faster vs. slower speeds for gait parameters in the direction of movement (SL, p = 0.007).

ConclusionImmediate responses and adaptations to mediolateral optic flow perturbations are speed-dependent and larger at slower gait speeds. The responses to prolonged perturbation are interpreted as step-to-step adaptations that may inform future interventions and studies on gait speed selection.

Dietary restriction promotes neuronal resilience via ADIOL
The steroid hormone 5-androstene-3{beta},17{beta}-diol (ADIOL) was discovered in humans nearly a century ago, yet its physiological roles remain poorly defined. Here, we show that fasting and caloric restriction, two forms of dietary restriction, induce transcriptional upregulation of genes encoding CYP11A1, CYP17A1, and 17{beta}-hydroxysteroid dehydrogenase family enzymes, promoting ADIOL biosynthesis. ADIOL, in turn, acts on the nervous system to reduce levels of kynurenic acid, a neuroactive metabolite linked to cognitive decline and neurodegeneration. This effect requires NHR-91, the C. elegans homolog of estrogen receptor {beta}, specifically in the RIM neuron, a key site of kynurenic acid production. Consistent with the known benefits of fasting and caloric restriction on healthspan, enhancing ADIOL signaling improves multiple healthspan indicators during aging. Conversely, animals deficient in ADIOL signaling exhibit reduced healthspan under normal conditions and in genetic models of caloric restriction, underscoring the functional significance of this pathway. Furthermore, ADIOL suppresses cellular stresses induced by the Alzheimers-associated APOE4 variant, highlighting its potential as a neuroprotective agent. Notably, ADIOL does not significantly impact lifespan, indicating that its healthspan benefits are not simply a byproduct of lifespan extension. Together, these findings establish a physiological role for ADIOL in mediating the neuroprotective and pro-healthspan effects of fasting and caloric restriction and suggest that boosting ADIOL signaling may help narrow the gap between lifespan and healthspan. This positions ADIOL as a promising mimetic of dietary restriction effects on healthspan that could be used as a therapeutic strategy for age-related neurodegenerative conditions.

GRAPHICAL ABSTRACT

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SORLA upregulation suppresses global pathological effects in aged tauopathy mouse brain
A role for the trafficking receptor SORLA in reducing A{beta} levels has been well-established, however, relatively little is known with respect to whether and how SORLA can potentially affect tau pathology in vivo. Here, we show that transgenic SORLA upregulation (SORLA TG) can reverse pathological effects in aged PS19 (P301S tau) mouse brain, including tau phosphorylation and seeding, ventricle dilation, synapse loss, LTP impairment and glial hyperactivation. Proteomic analysis indicates reversion of PS19 profiles in PS19/SORLA TG hippocampus, including pathological changes in synapse-related proteins as well as key drivers of synaptic dysfunction such as Apoe and C1q. snRNA-seq analysis reveals suppression of PS19- signatures with SORLA upregulation, including proinflammatory induction of Plxnb1/Plxnb2 in glia. Tau seeding and aggregation, neuroinflammation, as well as PlxnB1/B2 induction are exacerbated in PS19 hippocampus with SORLA deletion. These results implicate a global role for SORLA in neuroprotection from tau toxicity in PS19 mouse brain.

A systematic protocol to identify 'clinical controls' for pediatric neuroimaging research from clinically acquired brain MRIs
Progress at the intersection of artificial intelligence and pediatric neuroimaging necessitates large, heterogeneous datasets to generate robust and generalizable models. Retrospective analysis of clinical brain magnetic resonance imaging (MRI) scans offers a promising avenue to augment prospective research datasets, leveraging the extensive repositories of scans routinely acquired by hospital systems in the course of clinical care. Here, we present a systematic protocol for identifying "scans with limited imaging pathology" through machine-assisted manual review of radiology reports. The protocol employs a standardized grading scheme developed with expert neuroradiologists and implemented by non-clinician graders. Categorizing scans based on the presence or absence of significant pathology and image quality concerns, facilitates the repurposing of clinical brain MRI data for brain research. Such an approach has the potential to harness vast clinical imaging archives - exemplified by over 250,000 brain MRIs at the Childrens Hospital of Philadelphia - to address demographic biases in research participation, to increase sample size, and to improve replicability in neurodevelopmental imaging research. Ultimately, this protocol aims to enable scalable, reliable identification of clinical control brain MRIs, supporting large-scale, generalizable neuroimaging studies of typical brain development and neurogenetic conditions.

Inhibition of nonsense-mediated decay in TDP-43 deficient neurons reveals novel cryptic exons
TAR DNA-binding protein 43 kDa (TDP-43) is an essential splicing repressor whose loss of function underlies the pathophysiology of amyotrophic lateral sclerosis and frontotemporal dementia (ALS-FTD). Nuclear clearance of TDP-43 disrupts its function and leads to the inclusion of aberrant cryptic exons. These cryptic exons frequently introduce premature termination codons resulting in the degradation of affected transcripts through nonsense-mediated mRNA decay (NMD). Conventional RNA sequencing approaches thus may fail to detect cryptic exons that are efficiently degraded by NMD, precluding identification of potential therapeutic targets. We generated a comprehensive set of neuronal targets of TDP-43 in human iPSC-derived i3Neurons (i3N) by combining TDP-43 knockdown with inhibition of multiple factors essential for NMD, revealing novel cryptic targets. We then restored expression of selected NMD targets in TDP-43 deficient i3Ns and determined which genes improved neuronal viability. Our findings highlight the role of NMD in masking cryptic splicing events and identify novel potential therapeutic targets for TDP-43-related neurodegenerative disorders.

Heterogeneity and variability in short term synaptic plasticity and implications for signal transformation
There are many sources of heterogeneity in the CA1 network, including plasticity, connectivity and cell properties, yet the extent and functional consequences of this diversity remains poorly understood. We used patterned optogenetic stimulation of CA3 pyramidal neurons and whole-cell patch clamp recordings from CA1 pyramidal neurons in acute mouse hippocampal slices, to characterize the contributions of different forms of heterogeneity to information flow. We found pronounced heterogeneity in synaptic responses and short-term plasticity (STP), influenced by the neurotransmitter identity, input pattern, and size of the activated presynaptic ensemble. Inhibitory synapses exhibited greater diversity in both response variability and depression profiles than excitatory synapses. We incorporated these readings in a molecule-to-network multiscale model of the CA3->CA1 circuit. The reference model shows strong decorrelation of autocorrelated input, but removal of STP makes the decorrelation frequency dependent. Removal of stochasticity and heterogeneity in connections makes the output periodic. Thus heterogeneity, short-term plasticity, and stochasticity each have distinct effects on cellular information transmission.

Triceps Surae Muscle Ia Proprioceptive Weighting During Quiet Stance with Vision Occlusion
Visual, vestibular, proprioceptive and cutaneous sensory information is important for posture control during quiet stance. When the reliability of one source of sensory information used to detect self-motion for posture control is reduced, there may be a reweighting of inputs within and/or across the remaining sensory systems determining self-motion for postural control. Muscle vibration, which creates an illusion of muscle stretch and a compensatory movement to shorten the vibrated muscle, may be used to determine the weighting of muscle spindle Ia proprioception for posture control. The objective of this study was to determine the effect of vision occlusion on triceps surae muscle Ia proprioceptive weighting for postural control during quiet stance, utilizing 80 Hz muscle vibration and a quantitative measure of the bodys anterior to posterior ground center of pressure response to triceps surae muscle vibration in freely standing subjects. Subjects (N = 41; mean(standard deviation), 19.6(2.0) years) were examined as they stood with eyes open or eyes closed. Ground center of pressure was measured during quiet standing with, and without, bilateral vibration of the triceps surae muscles. The mean backward center of pressure shift induced by triceps surae vibration was significantly greater during the eyes closed condition compared to eyes open (eyes closed: -4.93(1.62) centimeters; eyes open: -3.21(1.33) centimeters; p = 6.85E-10; Cohens d = 1.29). Thirty-seven subjects increased, and two subjects decreased, their vibration induced center of pressure backward shift in the eyes closed condition compared to eyes open, although the magnitude of the change varied. Results support the idea that for most subjects, during an eyes closed stance there is an increased triceps surae muscle Ia proprioceptive weighting for postural control, due to the need for posture control to depend more on non-visual feedback.

Prior knowledge influences the neural mechanisms supporting memory-based inference
Memory-based inference allows individuals to integrate information acquired across separate episodes to support novel decisions and reasoning. Although prior knowledge, such as schemas, is known to influence learning and memory, its impact on the neural mechanisms underlying inference remains unclear. In this study, we investigated how schema congruency affects the encoding and retrieval of overlapping events and how these processes contribute to memory-based inference. Thirty-nine participants encoded AB associations, consisting of picture-word pairs presented on either schema-congruent or schema-incongruent backgrounds. These were followed by BC associations involving the same word paired with a new picture on a neutral background. At test, participants were asked to infer the indirect AC association. While overall inference accuracy did not differ as a function of schema congruency, behavioral and neural data revealed distinct mechanisms. Inference for schema-incongruent events depended on accurate retrieval of both AB and BC associations, whereas schema-congruent inferences did not. To investigate the neural processes involved, we trained hierarchical multivariate pattern classifiers on EEG data to detect schema and context reinstatement during task performance. For schema-congruent events, successful inference was predicted by schema reinstatement during BC encoding, consistent with integrating overlapping information into a unified memory trace. In contrast, successful inference for schema-incongruent events was predicted by context reinstatement during AC retrieval, reflecting a reliance on flexible recombination of separate memory representations. These findings demonstrate that schema congruency modulates the neural basis of memory-based inference. Congruent events are integrated during encoding, whereas incongruent events rely on retrieval-based inference.

Significance StatementTo make informed decisions, we often need to combine information from separate events. This study shows that prior knowledge, or schemas, affects how the brain forms these connections to make inferences about the world. Using EEG and machine learning, we found that when new information fits with existing schemas, people usually integrate memories during learning. In contrast, when information conflicts with prior knowledge, successful inference depends on retrieving and merging separate memories at the time of the decision. These findings reveal that the brain can switch between encoding and retrieval strategies based on prior knowledge, providing new insight into how memory supports reasoning, decision-making, and adaptive behavior.

Stretching of the insect mechanoreceptor evokes mechano-electrical transduction in auditory chordotonal neurons
Insect proprioception, vibration and sound detection rely on the scolopidium--a mechanosensory unit enclosing the sensory cilium of chordotonal organ neurons. The cilium contains mechanosensitive ion channels, and is enclosed by a scolopale cell with its tip embedded in a cap. Despite knowledge of the scolopidiums structure in multiple insects, the mechanism by which mechanical force elicits the transduction current remains speculative. We examined scolopidia in the auditory Mullers organ of the desert locust and present a comprehensive three-dimensional ultrastructure of a scolopidium using Focused Ion Beam Scanning Electron Microscopy (FIB-SEM). Next, we characterised sound-evoked motions of Mullers organ and the scolopidium using Optical Coherence Tomography (OCT) and high-speed light microscopy. We further measured transduction currents via patch clamp electrophysiology during mechanical stimulation of individual scolopidia. By combining ultrastructure, sound-evoked motions, and transduction current recordings, our finding suggests that the scolopidium is activated best by stretch along the ciliary axis.

Identifying out-of-voxel echoes in edited MRS with phase cycle inversion
1.PurposeTo identify the origin of out-of-voxel (OOV) signals based on the coherence transfer pathway (CTP) formalism using signal phase conferred by the acquisition phase cycling scheme. Knowing the CTP driving OOV artifacts enables optimization of crusher gradients to improve their suppression without additional data acquisition.

Theory and MethodsA phase cycle systematically changes the phase of RF pulses across the transients of an experiment, encoding phase shifts into the data that can be used to suppress unwanted CTPs. We present a new approach, phase cycle inversion (PCI), which removes the receiver phase originally applied to the stored transients, replacing it with new receiver phases, matching the phase evolutions associated with each unwanted CTP, to identify the OOV signals. We demonstrated the efficacy of PCI using the MEGA-edited PRESS sequence in simulations, phantom and in vivo experiments. Based on these findings, the crusher gradient scheme was optimized.

ResultsThe simulation results demonstrated that PCI can fully separate signals originating from different CTPs using a complete phase cycling scheme. PCI effectively identified the CTP responsible for OOV signals in phantom experiments and in vivo, though with reduced specificity in vivo due to phase instabilities. Re-optimization of the gradient scheme based on the identified OOV-associated CTP to suppress these signals, resulted in cleaner spectra in six volunteers.

ConclusionPCI can be broadly applied across pulse sequences and voxel locations, making it a flexible and generalizable approach for diagnosing the CTP origin of OOV signals.

Identification of Small Molecule Dimethyoxyphenyl Piperazine Inhibitors of Alpha-Synuclein Fibril Growth
Identification of Small Molecule Dimethyoxyphenol Piperazine Inhibitors of Alpha-Synuclein Fibril Growth Alpha-synuclein (asyn) fibril accumulation is the defining feature of Parkinson disease and is a target for disease-modifying treatments. One therapeutic strategy to reduce fibril accumulation is inhibition of asyn fibril growth. We developed a sensitive fluorescence-based fibril growth assay to screen for small molecule inhibitors. After validating the inhibition assay using a previously identified inhibitor, epigallocatechin-3-gallate, we identified compound 1 as a lead for inhibition of fibril growth. We analysed structure-activity relationships with analogs of 1 to optimize inhibition potency. Our results identified two dimethoxyphenyl piperazine analogs with more potent inhibition of in-vitro assembled fibrils. These analogs also inhibited the growth of asyn fibrils amplified from Lewy Body Disease brain tissue, further validating the inhibitor screening assay. Molecular docking studies indicate that these compounds can bind to the fibril ends, suggesting a potential capping mechanism through which these compounds inhibit the sequential association of monomeric asyn required for fibril growth.

The Vomeronasal System of Talpa occidentalis: A Combined Histological, Immunohistochemical, and Lectin-Binding Approach
The vomeronasal system (VNS) is critical for detecting pheromonal cues that modulate sociosexual behaviors. Despite its central role in chemical communication, our understanding of its anatomical and functional variability across mammals remains incomplete. This study provides the first detailed characterization of the VNS in the Iberian mole (Talpa occidentalis), a fossorial species endemic to the Iberian Peninsula. We performed a morphofunctional and neurochemical analysis of the vomeronasal organ (VNO) and the accessory olfactory bulb (AOB) using histology, immunohistochemistry, and lectin histochemistry. The VNO in T. occidentalis exhibited an unusual circular lumen lined by a uniform sensory epithelium, lacking the dual epithelial organization seen in most species. The vomeronasal cartilage was limited in extent and did not form the typical J-shaped structure. Importantly, no evidence of a vomeronasal pump was found, suggesting alternative mechanisms for semiochemical entry, likely facilitated by the organs anatomical position and continuous receptor distribution. Immunohistochemical analysis revealed strong expression of Gi2 and G{Upsilon}8 in sensory neurons, with weaker G0 expression, suggesting predominance of V1R-type signal transduction. The AOB, though small, exhibited clear lamination and specific marker localization (Gi2, OMP, CR, MAP2), indicating robust functional organization. Lectin binding revealed specific glycosylation patterns in the glomerular layer, with STL and LEA marking synaptic regions. These findings uncover unprecedented anatomical and molecular features in the VNS of T. occidentalis, positioning this species as a valuable model for studying vomeronasal diversity and evolution among Laurasiatherian mammals.

Forgetting in Drosophila consists of an increase in uncertainty rather than a stochastic loss of memory
While forgetting has been studied extensively in various organisms, its precise nature has often been unclear. Here, we used behavioral experiments in Drosophila to determine that a significant aspect of forgetting consists of a decrease in the ability of a memory to induce an appropriate behavior. We tested flies for memory retention at various times after training and then separately retested both flies that chose correctly and those that chose incorrectly. Although the ability to choose correctly decreased over time, we could not measure any differences in memory between flies that initially chose correctly and those that chose incorrectly upon retest. This suggests that forgetting is unlikely to consist of a spontaneous loss of a memory but instead consists of a decrease in the probability of flies that remember choosing the correct behavioral response. Thus, although flies maintain memory over time, there is an increase in uncertainty associated with this memory. We find that forgetting of long-term memories and accelerated forgetting in old flies occur in a similar manner.

TRPML3 regulates neuronal gene expression in an in vitro model of autophagy and may act as a genetic marker of familial neurodegenerative disorders
Autophagy is a conserved pro-survival pathway for delivering misfolded proteins and damaged organelles to lysosomes for degradation and protein homeostasis. Anomaly in autophagy leads to aberrant protein aggregation in neuronal cells, which is a common etiology of neurodegenerative disorders. Endo-lysosomal cation channel TRPML3 (Transient Receptor Potential Mucolipin-3) has been shown to induce autophagy in cell line models. However, the mechanism of TRPML3 mediated autophagy induction and the underlying gene expression changes are not clearly understood. Here, by using Ca2+-and electrical-current measurements, RNA sequencing and RT PCR studies, we explored the cellular function of TRPML3 and the global transcriptomic profile in a cell-based serum starvation model of autophagy. We report that serum starvation leads to downregulation of neuronal developmental genes during autophagy induction. TRPML3 overexpression further amplifies the effect of starvation in downregulating neuronal gene expression. But, when nutrition is not a limiting condition, TRPML3 overexpression upregulated neuronal genes including those responsible for axon guidance, synaptogenesis, and dendritic arborization. TRPML3 mediated neuronal gene expression changes were, presumably, due to transcription factors (TF) TFEB, FOXO1 and neuron-specific TFs such as SOX2, and ETV5. To further validate the role of TRPML3 in neuronal gene regulation, we performed meta-analysis of publicly available RNAseq datasets on neurodegenerative disorders which provided insight into the heterogeneity in the molecular mechanisms of autophagy and corroborated the TFEB-mediated autophagy induction and neuronal gene expression in TRPML3 overexpression condition. Based on our results, we propose that TRPML3 may act as a potential genetic marker for familial neurodegenerative disorders.

Non-equilibrium Thermodynamics Modulate TRPV1 Channel Activation via Tissue Entropy Production
Inflammatory processes involve complex interactions between molecular signaling and biophysical mechanisms, yet the thermodynamic consequences of such processes remain underexplored. Here, we present a theoretical multiscale model that demonstrates how elevated entropy production in inflamed tissue environments modulates the activation threshold of TRPV1 thermosensitive ion channels. Our framework integrates axonal electrophysiology based on the Hodgkin-Huxley formalism, thermodynamic heat transfer with explicit entropy generation, and a dynamic model of TRPV1 channel gating. Simulations reveal that increased entropy production leads to a downward shift in the activation temperature of TRPV1 channels, driven by cumulative non-equilibrium thermodynamic effects. This result provides a mechanistic explanation for the enhanced excitability of sensory axons in inflamed tissue and highlights entropy production as a fundamental physical variable influencing ion channel behavior. The study contributes a novel perspective on the coupling between thermodynamics and sensory transduction at the cellular level.

Altered Brain Energy Metabolism in the APPPS1 Alzheimer's Model during anesthesia: Integration of Experimental Data and In Silico Modeling
BackgroundSynaptic transmission and network activity rely on high ATP turnover. Impairments in cerebral energy metabolism are increasingly recognized as central in aging and Alzheimers disease (AD) pathogenesis. Elderly patients and patients with AD are also at elevated risk for perioperative neurological complications, including post-operative delirium and further cognitive deterioration. However, the interaction between metabolic vulnerability and anesthetic exposure remains incompletely understood.

MethodsWe investigated cortical metabolic responses and potassium homeostasis in acute brain slices from wild-type (WT) and AD-like APPPS1 transgenic mice, which were either exposed to isoflurane or left untreated. Glia cells were assessed by staining microglia and astrocytes. Measurements of the cerebral metabolic rate of oxygen (CMRO2), extracellular potassium dynamics, and proteomic profiling were integrated with computational modeling to assess oxidative metabolism and anesthetic effects under different conditions.

ResultsAPPPS1 mice exhibited reduced CMRO2 and attenuated neuronal activity compared to age-matched WT controls, showing sex-specific differences. Proteomic analysis revealed the downregulation of key mitochondrial and glycolytic enzymes, indicating an impaired ATP- generating capacity. Exposure to isoflurane further suppressed CMRO2, with a more pronounced effect in the APPPS1 brain tissue, while glia cells exhibited no acute changes. Additionally, isoflurane exacerbated deficits in extracellular potassium ([K]) clearance, highlighting impaired ion homeostasis under anesthetic challenge.

ConclusionsOur findings demonstrate that AD-like pathology in APPPS1 mice is associated with a significant decline in oxidative metabolism and ATP availability. These deficits are exacerbated by anesthetic exposure, contributing to impaired potassium regulation. This suggests that diminished metabolic flexibility may underlie increased anesthetic vulnerability and postoperative complications in AD.

Early postnatal CA3 hyperexcitability drives hippocampal development and epileptogenesis in SCN2A developmental and epileptic encephalopathy
Developmental and epileptic encephalopathies caused by pathogenic variants in SCN2A (SCN2A-DEE), encoding the voltage-gated sodium channel Nav1.2, present with early-life seizures, developmental delay, and increased mortality. Using a novel Scn2a p.A263V gain-of-function (GOF) mouse model, we demonstrate gene-dose and background-dependent phenotypes ranging from self-limited neonatal seizures to chronic epilepsy with high mortality. In vivo electrophysiology revealed hippocampal seizures as early as postnatal day 2.5, with CA3-driven gamma oscillations preceding seizure onset. CA3 and CA1 pyramidal neurons exhibited transient hyperexcitability during early postnatal development, resolving by P24-30. Single-cell RNA sequencing uncovered gene dose-dependent accelerated maturation of hippocampal networks, peaking at P7, alongside widespread transcriptional changes in excitatory and inhibitory neurons. In adulthood, persistent hippocampal network alterations emerged, marked by reduced mid-gamma oscillations and theta-gamma coupling. Our findings establish hippocampal CA3 hyperexcitability as an early driver of epileptogenesis in SCN2A-DEE and highlight it as a potential therapeutic target to mitigate disease progression.

Interleaved Replay of Novel and Familiar Memory Traces During Slow-Wave Sleep Prevents Catastrophic Forgetting
Humans and animals can learn continuously, acquiring new knowledge and integrating it into a pool of lifelong memories. Memory replay during sleep has been proposed as a powerful mechanism contributing to interference-free new learning 1-5. In contrast, artificial neural networks suffer from a problem called catastrophic forgetting 6-9, where new training damages existing memories. This issue can be mitigated by interleaving training on new tasks with past data 6,10,11; however, whether the brain employs this strategy remains unknown. In this work, we show that slow-wave sleep (SWS) employs an interleaved replay of familiar cortical and novel hippocampal memory traces within individual Up states of the slow oscillation (SO), allowing new memories to be embedded into the existing pool of cortical memories without interference. Using a combination of biophysical modeling and analyses of single-unit activity from the mouse retrosplenial cortex - for a mouse trained first in a highly familiar environment and then in a novel one - we found that hippocampal ripples arriving near the Down-to-Up or Up-to-Down transitions of the sleep SO can entrain novel memory replay, while the middle phase of the Up state tends to replay familiar cortical memories. This strategy ensures the consolidation of novel cortical memory traces into long-term storage while minimizing damage to familiar ones. This study presents a novel framework for how replay of familiar and novel memory traces is organized during SWS to enable continual learning.

IP3-mediated Ca2+ transfer from ER to mitochondria stimulates ATP synthesis in primary hippocampal neurons
During electrical activity, Ca2+ enhances mitochondrial ATP production, helping to replenish the energy consumed during this process. Most Ca2+ enters the cell via ligand- or voltage-gated channels on the neuronal membrane, where it stimulates the release of additional Ca2+ from the endoplasmic reticulum (ER). Although the influence of cytosolic Ca2+ on neuronal metabolism has been widely investigated, relatively few studies have explored the contribution of ER Ca2+ release in this context. Therefore, we investigated how activity-driven Ca2+ crosstalk between the ER and mitochondria influences the regulation of mitochondrial ATP production. We show that in primary hippocampal neurons derived from rat pups of either sex, depletion of ER Ca2+ led to a reduction in mitochondrial Ca2+ levels during both resting and stimulated states, while exerting only a minimal impact on cytosolic Ca2+ levels. Additionally, impaired ER-mitochondria Ca{superscript 2} transfer led to a reduction in mitochondrial ATP production. Similar effects were observed when inositol-3-phosphate receptors (IP3Rs), but not ryanodine receptors (RyRs), were pharmacologically inhibited. Together, our findings show that, in hippocampal neurons, Ca2+ is transferred from the ER to mitochondria through IP3 receptors, and this Ca2+ crosstalk in turn enhances mitochondrial ATP production in response to neuronal activity.

HighlightsO_LICa2+ adjusts mitochondrial ATP synthesis to neuronal activity
C_LIO_LIIn the neuronal somata ER-mitochondria Ca2+ crosstalk occurs via IP3 receptors
C_LIO_LIIP3-mediated Ca2+ release occurs across a wide range of firing intensities.
C_LI

Spatial Reorganization of Object Representations in High-Level Visual Cortex Distinguishes Working Memory from Perception
The human visual system balances veridical object visual perception with flexible object visual working memory (VWM), both relying on high-level visual regions. However, how these competing demands shape spatial representations remains unclear. Here, we ask whether VWM inherits the spatial constraints observed in the lateral occipital complex (LOC) during perception, or instead reorganizes these representations to meet mnemonic demands. Using matched bilateral presentation paradigms and fMRI-based decoding, we systematically compared spatial representations during perception and VWM. This approach revealed a striking dissociation: during perception, object information is largely confined to the contralateral LOC, whereas during VWM, robust ipsilateral representations emerge--even when both hemifields must be remembered. Vertex-ablation analyses revealed that VWM engages 70-90% of ipsilateral LOC territories, far exceeding those recruited during unilateral perception. Neither increased attentional span nor top-down feedback from association areas fully explained this expansion; rather, ipsilateral LOC patterns closely mirrored contralateral sensory representations, implicating interhemispheric coordination in VWM. Together, these findings demonstrate that object VWM flexibly recruits distributed high-level visual cortex, with spatial reorganization distinguishing mnemonic flexibility from perceptual fidelity.

Intrinsic mechanisms contributing to the biophysical signature of mouse gamma motoneurons
Precise motor control relies on continuous sensory feedback from muscles, a process in which gamma motoneurons play a key role. These specialized spinal neurons innervate intrafusal muscle fibres, modulating their sensitivity to stretch and maintaining proprioceptive signalling during movement. Gamma motoneurons are characterized by a distinct biophysical profile, including low recruitment thresholds and high firing rates that enable rapid activation of intrafusal fibres at contraction onset. Despite their importance, the intrinsic mechanisms that underlie these properties remain poorly understood. In this study, we analysed published and unpublished data to identify a population of low-threshold, high-gain motoneurons with features consistent with gamma motoneurons, emerging during the third postnatal week in mice. Their low recruitment threshold was linked to lower membrane capacitance, higher input resistance, a more hyperpolarized activation of persistent inward currents (PICs), and a narrower axon initial segment. In contrast, higher firing rates were associated not with PIC amplitude but with shorter action potential durations and smaller medium afterhyperpolarizations. Notably, 92% of putative gamma motoneurons exhibited a sodium pump-mediated ultra-slow afterhyperpolarization (usAHP), which was absent in slow alpha motoneurons. This difference could not be attributed to h-current activity or expression of the alpha 3 subunit of the sodium-potassium ATPase. These findings reveal key intrinsic properties that support the unique excitability of gamma motoneurons, offering new insight into their contribution to motor control. This work provides a foundation for future studies into their development, regulation, and involvement in neuromuscular disorders.

Key Points[bullet] A distinct cluster of motoneurons with low recruitment current and high firing gain, characteristic of gamma motoneurons, emerges in the third week of postnatal development.
[bullet]Gamma motoneurons have a low recruitment current due to lower capacitance, higher input resistance, and a more hyperpolarized activation voltage for persistent inward currents.
[bullet]Their high firing rates are not driven by differences in persistent inward current amplitude but are instead attributed to shorter duration action potentials and smaller amplitude medium afterhyperpolarizations.
[bullet]A narrower axon initial segment in gamma motoneurons may contribute to their increased excitability compared to alpha motoneurons.
[bullet]Gamma motoneurons present with a higher prevalence of ultra slow afterhyperpolarization than slow alpha motoneurons that cannot be accounted for by differences in h-current or expression of alpha 3 subunits of the sodium potassium ATPase pump.

Switches in Orientation Coding by Mouse Primary Visual Cortex Neurons Depend on Stimulus Predictability.
How the brain processes a stimulus depends on contextual factors, such as whether it is predictable or surprising. While this process has been partially characterized using EEG and fMRI, and invasive cellular approaches, the microcircuit mechanisms responsible for comparing sensory input and expectations remain poorly understood. Here, we combined layer-resolved recordings of single-unit activity and local field potentials (LFP) in mouse primary visual cortex (V1) with a visual oddball paradigm using oriented gratings. Both event-related potentials and firing rates exhibited distinct temporal components across cortical layers and trial types. We identified robust stimulus-specific adaptation (SSA), mismatch negativity (MMN), and deviant detection (DD) contrast at both early and late epochs. Surprisingly, a substantial subset of excitatory neurons exhibited complete reversals of orientation preference ("preference switches") between standard and deviant trials, rather than only changes in selectivity. These preference-switching cells were primarily observed in layers 2/3 and 5/6 and contributed as much information to stimulus decoding as stably tuned neurons. Our findings demonstrate that context-dependent flexibility in feature preference is an integral part of predictive coding in V1 and challenge the notion of fixed stimulus representations at the single-neuron level.

Sephin1 alleviates white matter injury by protecting oligodendrocyte after intracerebral hemorrhage
BackgroundWhite matter injury (WMI) caused by intracerebral hemorrhage (ICH) is a major neuropathological feature closely associated with neurological impairments such as motor and sensory dysfunction. Oligodendrocytes (OLs), which are responsible for repairing WMI, also suffer severe death resulting from the compression of hematoma and secondary neuroinflammation after ICH. Sephin1, a selective inhibitor of PPP1R15A, has been shown to reduce general protein synthesis and protect OLs by prolonging the integrated stress response (ISR). We aimed to evaluate the effectiveness of Sephin1 in protecting OLs in experimental ICH mice and primary OLs and microglia co-cultures.

MethodsWe first determined the performance of ICH mice treated with Sephin1 or vehicle in multiple behavioral tests. To investigate dynamic changes in the number of OLs surrounding the hematoma after ICH, we labeled and tracked apoptotic, proliferating, and mature OLs using immunofluorescence staining.

ResultsSephin1 treatment improved long-term neurological function after ICH, which was accompanied by a significant alleviation of WMI in the perihematomal region. Our data indicated that Sephin1 dramatically increased the population of OLs in the perihematomal region after ICH by inhibiting OL apoptosis and promoting OL proliferation. Moreover, Sephin1 treatment attenuated neuroinflammation after ICH by inhibiting microglial polarization to the M1 phenotype. In vitro, a co-culture model of primary OLs and microglia demonstrated that Sephin1 preserved the viability of OLs under pro-inflammatory conditions.

ConclusionsOur observations suggest that Sephin1 is a promising therapeutic drug to preserve the OLs and alleviate WMI around the hematoma in ICH, highlighting its translational potential to improve long-term neurological recovery in hemorrhagic stroke.

Luminal Vascular Dysfunction Drives Rapid Blood Brain Barrier Injury in Hyperglycemic Stroke: Key Roles for Luminal Glycocalyx and Complement
BackgroundAcute hyperglycemia affects approximately 40% of stroke patients and is associated with worse outcomes. The underlying mechanisms linking this metabolic stress to stroke-induced brain injury remains unclear, and effective therapies are lacking.

MethodsIn a mouse model of acute hyperglycemic stroke, luminal disruption, blood-brain barrier (BBB) leakage, neurological deficit, motor function, and mortality were evaluated. Vascular luminal glycocalyx and complement activation were assessed by immunostaining, with glycocalyx loss confirmed by electron microscopy. Complement C3s causal role was tested using C3 knockout mice and site-targeted inhibition with CR2-Crry. To enhance translational relevance, post-mortem human stroke and control brains were immunostained to assess the association between endothelial glycocalyx loss and vascular complement activation. In a separate stroke patient cohort, soluble complement activation products were measured in pre-thrombectomy plasma, and their predictive value for modified Rankin Scale (mRS) outcomes evaluated using elastic net regression.

ResultsHyperglycemic stroke mice exhibited accelerated and more severe BBB breakdown, greater functional deficits, and higher mortality than normoglycemic controls, mirroring clinical observations. Acute hyperglycemia triggered rapid vascular luminal injury characterized by loss of endothelial luminal glycocalyx, luminal IgM/IgG deposition, and vascular complement C3 activation, leading to BBB disruption. This vascular luminal injury was corroborated in human stroke brain tissue. These luminal changes persisted despite glucose normalization and were exacerbated by reperfusion, driving injury into the brain parenchyma. Genetic and pharmacological approaches confirmed vascular complement activation as a causal driver of severe BBB disruption and poor outcomes. Importantly, site-targeted pharmacological inhibition of complement after reperfusion preserved BBB integrity and improved outcomes, defining a time-specific, luminal-directed strategy as a promising adjunct to thrombectomy. Notably, soluble complement activation markers in pre-thrombectomy stroke plasma predicted clinical outcomes, highlighting their potential as pre-intervention markers for patient stratification and tailored therapy.

ConclusionThis study reframes acute hyperglycemic stroke as a vascular luminal disorder, establishing a novel Metabolic-Complement-Vascular (MCV) axis linking metabolic stress to endothelial luminal glycocalyx loss, vascular complement activation, and BBB breakdown in both mice and humans. This new mechanistic understanding transforms the therapeutic landscape of hyperglycemic stroke, offering a potential time-defined, luminal-focused adjunct therapy alongside thrombectomy.

Clinical PerspectiveO_ST_ABSWhat Is New?C_ST_ABS- This study reframes hyperglycemic stroke as an acute vascular luminal problem, marked by rapid loss of endothelial luminal glycocalyx and complement C3 activation at the vascular luminal surface.
- The rapid luminal changes, identified in both rodent and human stroke brain tissues, establish a novel Metabolic-Complement-Vascular (MCV) axis linking metabolic stress to luminal damage, blood-brain barrier (BBB) breakdown, and injury progression into the brain parenchyma.
- The first clinical evidence that pre-thrombectomy plasma complement activation markers independently predict stroke outcomes -- laying the foundation for risk stratification before reperfusion and precision adjunct therapies.

What Are the Clinical Implications?- The rapidity and persistence of the MCV axis activation--even after glucose normalization--help explain the limited efficacy of insulin therapy, shifting the therapeutic focus from glycemic control to luminal-targeted interventions.
- Identification of a narrow but actionable window following reperfusion where complement C3 inhibition preserves the BBB and limits injury progression to the parenchyma, offers a promising adjunct to thrombectomy in metabolically vulnerable stroke patients.
- Targeting the vascular luminal surface reshapes the therapeutic landscape for hyperglycemic stroke by enabling systemic interventions--bypassing the challenge of BBB penetration, supporting rapid clinical translation using existing FDA-approved C3 inhibitors, and framing the endothelial glycocalyx as a promising area for therapeutic and diagnostic exploration in hyperglycemic stroke and broader cerebrovascular disease.

Longitudinal Imaging of Experimental Intracerebral Hemorrhage Pathology with Iodine-enhanced Micro-CT
BackgroundIodine-enhanced micro-computed tomography (Micro-CT) enables high-resolution three-dimensional imaging of brain architecture. This study aimed to characterize both acute and chronic pathological changes following intracerebral hemorrhage (ICH) using iodine-enhanced micro-CT.

MethodExperimental ICH was induced in 8- to 10-week-old C57BL/6 mice (n = 76) via stereotaxic injection of either 0.075 U collagenase IV or 30 l autologous blood. Iodine-enhanced micro-CT imaging was performed at 4 hours, 1, 3, and 7 days after intracerebral hemorrhage post-ICH to evaluate hematoma formation and erythrolysis. Chronic alterations, including ventriculomegaly and ipsilateral lesion, were assessed at 28 days post-ICH. In parallel, MRI was conducted at 1, 7, and 28 days following autologous blood injection, followed by micro-CT, to facilitate cross-modality quantitative analysis. Lesion volumes were compared between imaging modalities over time.

ResultsMicro-CT enabled quantification of hematoma volume and erythrolysis in ICH models. Hematomas extended along perivascular pathways toward the cerebral surface in both collagenase- and autologous blood-induced ICH models. At 28 days post-ICH, micro-CT detected ventriculomegaly and hypodense lesions without concurrent expansion of the choroid plexus. Lesion volume measurements derived from micro-CT correlated with those from MRI, enabling quantitatively assessment of iron deposition and hematoma size alterations after ICH.

ConclusionIodine-enhanced micro-CT provides a robust and high-resolution imaging platform for evaluating hematoma evolution, hemolysis, ventricular enlargement, and chronic brain lesions in experimental ICH. When integrated with MRI, these multimodal imaging approaches enhance the characterization of both hematoma volume and iron deposition following ICH.

Power Pixels: a turnkey pipeline for processing of Neuropixel recordings
There are many open-source tools available for the processing of neuronal data acquired using Neuropixels probes. Each of these tools, focuses on a part of the process from raw data to single neuron activity. For example, SpikeInterface is an incredibly useful Python module for pre-processing and spike sorting of individual recordings. However, there are more steps in between raw data and spikes, such as synchronization of spike times between probes and histological reconstruction of probe insertions. Therefore, we developed Power Pixels, combining the functionality of several packages into one integrated pipeline, which may be run in any lab workflow. It includes pre-processing, spike sorting, neuron-level quality control metrics, synchronization between multiple probes, compression of raw data, and ephys-to-histology alignment. Integrating all these steps into one pipeline greatly simplifies Neuropixels data processing, especially for novel users who might struggle to find their way around all the available code and tools.