bioRxiv Subject Collection: Neuroscience's Journal

Fusobacteria nucleatum determines the expression of amphetamine-induced behavioral responses through an epigenetic phenomenon.
Amphetamines (AMPHs) are psychostimulants commonly used for the treatment of neuropsychiatric disorders. They are also misused (AMPH use disorder; AUD), with devastating outcomes. Recent studies have implicated dysbiosis in the pathogenesis of AUD. However, the mechanistic roles of microbes in AUD are unknown. Fusobacterium nucleatum (Fn) is a bacterium that increases in abundance in both rats and humans upon AMPH exposure. Fn releases short-chain fatty acids (SCFAs), bacterial byproducts thought to play a fundamental role in the gut-brain axis as well as the pathogenesis of AUD. We demonstrate that in gnotobiotic Drosophila melanogaster, colonization with Fn or dietary supplementation of the SCFA butyrate, a potent inhibitor of histone deacetylases (HDACs), enhances the psychomotor and rewarding properties of AMPH as well as its ability to promote male sexual motivation. Furthermore, solely HDAC1 RNAi targeted inhibition recapitulates these enhancements, pointing to a specific process underlying this Fn phenomenon. Of note is that the expression of these AMPH behaviors is determined by the increase in extracellular dopamine (DA) levels that result from AMPH-induced reversal of DA transporter (DAT) function, termed non-vesicular DA release (NVDR). The magnitude of AMPH-induced NVDR is dictated, at least in part, by DAT expression levels. Consistent with our behavioral data, we show that Fn, butyrate, and HDAC1 inhibition enhance NVDR by elevating DAT expression. Thus, the participation of Fn in AUD stems from its ability to release butyrate and inhibit HDAC1. These data offer a microbial target and probiotic interventions for AUD treatment.

Axon Trafficking Counteracts Aberrant Protein Aggregation in Neurons
Directed axon trafficking of mRNA via ribonucleoprotein complexes (RNPs) is essential for the proper function and survival of neurons. However, the mechanisms governing RNP transport in axons remain poorly understood. Here, we identify Annexin A7 (ANXA7) as a critical adaptor facilitating the retrograde transport of T-cell intracellular antigen 1 (TIA1)-containing RNPs by linking them to the cytoplasmic dynein. Persistent axonal Ca2+ elevation disrupts ANXA7's linker role, causing the detachment of TIA1 granules from dynein, consequently impairing transport and triggering pathological TIA1 aggregation within axons. Similarly, ANXA7 knockdown decouples TIA1 granules from dynein, severely obstructing trafficking and causing pathological aggregation of TIA1 in axons, which culminates in axonopathy and neurodegeneration both in vitro and in vivo. Conversely, ANXA7 overexpression enhances trafficking and counteracts aberrant aggregation of TIA1-containing RNPs in axons. Our findings elucidate a novel mechanism underlying RNP axonal transport, highlighting its significance in the biology and pathology of central neurons.

Childhood Maltreatment and Brain Aging During Adulthood
Importance: Childhood maltreatment (CM) is associated with the early onset of psychiatric and medical disorders and accelerated biological aging. Objective: To identify types of maltreatment and developmental sensitive periods that are associated with accelerated adult brain aging. Design: Participants were mothers of infants recruited from the community into a study assessing the effects of CM on maternal behavior, infant attachment, and maternal and infant neurobiology. Data were collected from July 2015 to November 2019 and were analyzed from July 2023 to October 2024. Setting: Academic medical centers. Participants: High-quality MRI scans were obtained on 92 of 150 mothers enrolled in the study. The main exclusion criteria for neuroimaging were histories of head trauma with loss of consciousness or concussion, psychotropic use before age 18, pregnancy, and customary MRI exclusions (e.g., metal implant). The primary reasons for non-completion of the neuroimaging study were unwillingness to be scanned, inability to attend the MRI study visit due to work and/or childcare, metal implants, or pregnancy. Main Outcome(s) and Measure(s): The Maltreatment and Abuse Chronology of Exposure scale was used to retrospectively assess the annual severity of exposure to ten types of CM from birth to age 18 years. Brain age was calculated from T1-weighted 3T MRI Scans using a previously published machine learning algorithm. Sensitive periods were identified using random forest regression with conditional inference trees. Results: Forty-nine (53.3%) of the 92 mothers (mean [SD] age, 32.4 [4.3] years) reported experiencing one or more types of CM. Total CM severity was associated with accelerated brain aging (beta=0.05, 95% CI, 0.02 to 0.09, p<.005). The most robust type/time risk factors for accelerated brain aging were parental physical abuse between ages 4 to 6 years, witnessing sibling violence between ages 4 to 15 years, parental verbal abuse between ages 10 to 12 years, and parental emotional neglect between ages 16 to 18 years. Conclusions and Relevance: Several types of CM between ages 4-18 years were associated with accelerated brain aging. Understanding how these specific types and ages of exposure contribute to accelerated brain aging may provide important insights into preventing key clinical consequences of CM.

Prior use-dependent plasticity triggers different individual corticomotor responses during persistent musculoskeletal pain
Movement repetition is crucial for pain interventions. It facilitates the rehabilitation of motor patterns, the acquisition of motor skills and the genesis of adaptive use-dependent plasticity. However, the influence of prior motor experience and pre-existing use-dependent plasticity on pain severity and progression remains poorly investigated. This study investigated the effects of pre-existing use-dependent plasticity during the development of prolonged experimental musculoskeletal pain. Using transcranial magnetic stimulation, corticospinal excitability was assessed by measuring the rest-motor thresholds (RMTs), motor-evoked potential (MEP), representational area of the motor map, volume, and center of gravity of the first dorsal interosseous (FDI) muscle in musicians (n=19), a well-known ecological model of use-dependent plasticity, and in non-musicians (n=20). All participants attended three sessions (Day1, Day3, Day8). Prolonged pain for several days was induced by intramuscular injection of nerve growth factor (NGF) into the right FDI muscle at the end of Day1. Compared to Day1, prolonged pain uniquely led to reduced motor map volume in non-musicians on Day3 (p=0.004), who also showed higher NGF-related pain intensity compared to musicians. The motor maps of musicians, which were already smaller in pain-free conditions (Day1) compared to non-musicians (p=0.021), remained non-significantly different across days. Notably, corticomotor responses (map volume, MEP amplitude, and RMTs) at Day1 were correlated to weekly and accumulated musical training. These findings demonstrate that pre-existing use-dependent plasticity associated with motor training may counteract the effects of prolonged pain in the motor system. Moreover, it confirms that prior motor experience acts as a source of individual variability to pain.

Cognitive enrichment preserves retrosplenial parvalbumin density and cognitive function in female 5xFAD mice
BACKGROUND: The rate of cognitive decline in Alzheimer's disease (AD) varies considerably from person to person. Numerous epidemiological studies point to the protective effects of cognitive, social, and physical enrichment as potential mediators of cognitive decline in AD; however, there is much debate as to the mechanism underlying these effects. The retrosplenial cortex (RSC) is one of the earliest brain regions with impaired functions during AD pathogenesis, and its activity is affected by cognitive, social, and physical stimulation. METHODS: In the current study, we use the 5xFAD mouse mode of AD to examine the impact of enriched housing conditions on cognitive function in AD and the viability of a particularly vulnerable cell population within the RSC - parvalbumin interneurons (PV-INs). RESULTS: Enriched housing conditions improved cognitive performance in 5xFAD mice. These changes in cognitive performance coincided with restored functional connectivity of the RSC and preserved PV-IN density within this region. Along with preserved PV-IN density, there was an increase in the density of perineuronal nets (PNNs) across the RSC of 5xFAD mice housed in enriched conditions. Direct manipulation of PNNs revealed that these extracellular matrix structures protect PV-INs from amyloid toxicity. CONCLUSIONS: Together, these results provide support for the PNN-mediated maintenance of PV-INs in the RSC as a potential mechanism mediating the protective effects of enrichment against cognitive decline in AD.

Comparison of TENS electrodes and textile electrodes for electrocutaneous warning
Electrocutaneous stimulation can be employed to alert workers in potentially hazardous situations. To determine the feasibility of a novel textile electrode cuff in comparison to previously used TENS electrodes, two studies were conducted. In a study on n = 30 participants, perception, attention, muscle twitch, and intolerance thresholds as well as qualitative and spatial perceptions, were determined for eight pairs of electrodes circumferentially placed around the upper right arm for TENS and for textile electrodes. In a second study on n = 36 participants, these thresholds were also determined during vibration, and a warning signal pattern was presented during vibration. We found smaller perception thresholds for the textile electrodes in comparison to the TENS electrodes for all 8 electrode pairs and occasional differences for the attention and intolerance thresholds, which might be mainly explained by the varying electrode sizes due to the manual production process of the textile electrodes. Stimulation using textile electrodes within the cuff showed less frequent muscle twitches compared to TENS electrodes. Other qualitative and spatial perceptions appeared comparable. The perception, attention, and intolerance thresholds increased during vibration comparable to previous results with TENS electrodes. The feasibility of using the textile electrodes during vibration and for the application of a warning signal was successfully demonstrated. Occasional cases occurred where the transition impedance was too high while using the textile electrodes. Future studies will focus on electrode optimization to achieve a wearable solution with both low electrode-skin transition impedance and minimal muscle twitching.

Optical recordings of unitary synaptic connections reveal high and random local connectivity between CA3 pyramidal cells
The hippocampal CA3 region is thought to play crucial roles in episodic memory functions because of the extensive recurrent connections between CA3 pyramidal cells (CA3PCs). However, different methods provided contradicting observations about the synaptic connectivity between CA3PCs. Therefore, we estimated the connectivity rate between individual CA3PCs using a new approach that is not affected by the confounds of conventional methods. Specifically, we used voltage imaging with the Voltron sensor in acute slices from rats of both sexes to test CA3PC connections by detecting spontaneous spiking and subthreshold responses in anatomically identified neurons. We detected 164 monosynaptic excitatory connections in 3078 tested CA3PC-CA3PC pairs. This 5.3% connectivity rate was much higher than that we observed with the theoretically more sensitive patch clamp method in similar experimental conditions, but it remained below the anatomically observed number of CA3PC-CA3PC contacts. We verified that the imaged excitatory connections were mediated by AMPA receptors. Our results also showed that the recurrent connections did not enrich into preferred connectivity motifs and followed a distribution that was consistent with random connectivity in general. Moreover, voltage imaging revealed CA3PCs with distinct firing properties and somatic locations corresponding to previously established heterogeneity and showed that specific connectivity rules create preferred information routes among these subpopulations. Finally, we showed that there is at least one condition, influencing patch clamp recordings but not voltage imaging, that affects the observable functional connections between CA3PCs. Altogether, our results obtained with a new voltage imaging approach argue for high local connectivity rates between CA3PCs.

Oral prodrug of a novel glutathione surrogate reverses metabolic dysregulation and attenuates neurodegenerative process in APP/PS1 mice
Glycation-induced oxidative stress underlies the numerous metabolic ravages of Alzheimer's disease (AD). Reduced glutathione levels in AD lead to increased oxidative stress, including glycation-induced pathology. Previously, we showed that the accumulation of reactive 1,2-dicarbonyls such as methylglyoxal, the major precursor of non-enzymatic glycation products, was reduced by the increased function of GSH-dependent glyoxalase-1 enzyme in the brain. In this two-pronged study, we evaluate the therapeutic efficacy of an orally bioavailable prodrug of our lead glyoxalase substrate, pro-{psi}-GSH, for the first time in a transgenic Alzheimer's disease mouse model. This prodrug delivers pharmacodynamically relevant brain concentrations of {psi}-GSH upon oral delivery. Chronic oral dosing of pro-{psi}-GSH effectively reverses the cognitive decline observed in the APP/PS1 mouse model. The prodrug successfully mirrors the robust effects of the parent drug i.e., reducing amyloid pathology, glycation stress, neuroinflammation, and the resultant neurodegeneration in these mice. We also report the first metabolomics study of such a treatment, which yields key biomarkers linked to the reversal of AD-related metabolic dysregulation. Collectively, this study establishes pro-{psi}-GSH as a viable, disease-modifying therapy for AD and paves the way for further preclinical advancement of such therapeutics. Metabolomic signatures identified could prove beneficial in the development of treatment-specific clinically translatable biomarkers.

Acute cortical stroke alters neural activity in the subthalamic nucleus, which correlates with motor disability in rats
Objectives: We aimed to investigate the impact of acute cortical stroke (ACS) on neural activity in subthalamic nucleus (STN). We then examined the correlation between changes in STN activity and motor disability. Methods: Forty-four Sprague-Dawley rats were used. While rats were anesthetized, we inserted electrodes in STN and induced an ACS by creating photothrombotic lesion in ipsilateral motor cortex. Local field potentials were recorded before and after ACS. The motor behavior was assessed before and after ACS using single pellet reaching task. Results: Rats experienced significant motor disability after ACS. STN firing rate significantly decreased after ACS. Additionally, delta (0.5-4 Hz) and gamma (50-140 Hz) power significantly decreased after ACS. Furthermore, the decrease in delta mean power correlated with decreases in success rate (r =0.77, p =0.009) and first try success rate (r =0.69, p =0.028). The decreases in gamma mean power (r =0.68, p =0.029) and gamma peak power (r =0.74, p =0.015) correlated with the decrease in success rate. The decrease in gamma power significantly correlated with the decreased STN firing rate. However, decreased delta power exhibited no correlation with decreased gamma power. Interpretation: ACS causes abnormal STN activity, which correlated with motor disability. Post-stroke STN inhibition may partially compensate for ACS. However, it could also lead to pathological consequences. This STN abnormal activity may serve as a biomarker for motor disability severity after ACS. Furthermore, our findings may provide a possibility for developing neuromodulation strategies, allowing to mitigate post-stroke motor disability through modulating abnormal STN activity.

Arc: a therapeutic hub for Alzheimer's disease.
Alzheimer's disease (AD) is poised to reach epidemic levels as the world population ages. There is currently no treatment that halts this debilitating disease. Our recent finding that the memory gene Arc regulates the expression of many genes associated with the pathophysiology of AD sets the stage for a new therapeutic approach that is not structurally based on the amyloid hypothesis that has driven most research to date. Neuronal activity-dependent Arc expression is controlled by a chromatin-modification complex containing two enzymes: Tip60 and PHF8. Here, we show that small molecules targeting these proteins inhibit Arc expression. This finding sets the stage for a novel therapeutic approach to combat Alzheimer's disease. Targeting Arc opens a new frontier of "multi-target" therapy designed to simultaneously intervene in several aspects of the disease. Because of Arc's role in controlling the expression of multiple genes and pathways implicated in AD, it could serve as a therapeutic hub.

Maternal motivation overcomes innate fear via prefrontal switching dynamics
Parental care is altruistic. In natural environments, parents are often faced with challenging environmental conditions, such as severe weather, complex terrain and predatory threats, and therefore need to overcome the fear of adverse conditions to protect and raise the offspring. Although a few studies have reported risk-taking maternal behaviors, it is unknown how maternal motivation and environmental threats are represented and integrated in neural circuits to resolve the conflict and dynamically drive behaviors. Here we report a novel risk-taking maternal behavior paradigm in a semi-naturalistic context, in which a female mouse has to overcome fear and jump off an elevated platform to retrieve pups outside a nest on the ground. We show that while fear of heights reduces the motivation to jump, the presence of pups dramatically facilitates overcoming such fear. A medial prefrontal-periaqueductal gray (mPFC-PAG) pathway is specifically required for the effect of pups on overcoming fear of height, and this circuit integrates conflicting cues about pup and height and encodes motivation to drive risk-taking jumping behaviors. In contrast to cued, fast and predictable reaction timing in typical structured tasks, behaviors in our paradigm are highly spontaneous, characterized by stochastic transitions between low-motivation and high-motivation states. Our data reveal that such spontaneity is shaped by the switching ramping dynamics of neural activity in the motivation-encoding dimension, rather than continuous ramping dynamics. Pup and height cues modulate the switching ramping dynamics to influence, but not immediately evoke behaviors. Together, we propose that the prefrontal-brainstem pathway plays vital roles in encoding altruistic motivation to overcome innate fear, and the switching ramping dynamics might represent a general mechanism that gives rise to spontaneous behaviors in naturalistic and conflicting conditions.

Associations between epilepsy-related polygenic risk and brain morphology in childhood
Temporal lobe epilepsy with hippocampal sclerosis (TLE-HS) is associated with a complex genetic architecture, but the translation from genetic risk factors to brain vulnerability remains unclear. Here, we examined associations between epilepsy-related polygenic risk scores for HS (PRS-HS) and brain structure in a large sample of neurotypical children, and correlated these signatures with case-control findings in in multicentric cohorts of patients with TLE-HS. Imaging-genetic analyses revealed PRS-related cortical thinning in temporo-parietal and fronto-central regions, strongly anchored to distinct functional and structural network epicentres. Compared to disease-related effects derived from epilepsy case-control cohorts, structural correlates of PRS-HS mirrored atrophy and epicentre patterns in patients with TLE-HS. By identifying a potential pathway between genetic vulnerability and disease mechanisms, our findings provide new insights into the genetic underpinnings of structural alterations in TLE-HS and highlight potential imaging-genetic biomarkers for early risk stratification and personalized interventions.

Behavioral investigation of allocentric and egocentric cognitive maps in human spatial memory
Spatial memory is a fundamental cognitive function that enables humans and other species to encode and recall the locations of items in their environments. Humans employ diverse strategies to support spatial memory, including the use of cognitive maps. Cognitive maps are mental representations of the environment that organize its content along two or more continuous dimensions. In allocentric cognitive maps, these dimensions form a Cartesian coordinate system referenced to the environment. In egocentric cognitive maps, the dimensions form a polar coordinate system centered on the subject. To better understand how humans employ allocentric and egocentric cognitive maps for spatial memory, we performed a behavioral study with a novel task designed to directly and explicitly assess both types of cognitive maps. During encoding periods, participants navigated through a virtual environment and encountered objects at different locations. During recall periods, participants aimed at remembering these locations in abstract allocentric and egocentric coordinate systems. Our results show that relationships between the objects and the environment, such as their distance to boundaries and corners, were associated with allocentric memory performance. Relationships between the objects and the participant, including their distance and orientation to the participant's starting position, were linked to egocentric memory performance. Spatial feedback during recall supported performance within allocentric and egocentric domains, but not across domains. These findings are compatible with the notion that allocentric and egocentric cognitive maps operate as (partially) independent systems for spatial memory, each specialized in processing specific types of spatial relationships.

Astrocyte Ca2+ activity regulates node of Ranvier length in the white matter
Nodes of Ranvier generate action potentials along myelinated axons, but it is unclear whether they can modulate neural circuit function. Computer modelling previously predicted that adjusting node length can control axonal conduction speed1, but it is unknown whether mechanisms controlling nodal structure operate in the healthy brain. Here, in brain slices and in intact white matter tracts of live mice, we found that nodes elongate and shorten, while an overall stable mean node length is maintained. Changes in node length were only detected in nodes that were flanked by compact myelin sheaths, and more motile nodes were observed as myelination progressed during development. In the developing brain, but not in adult mice, neuronal activity caused the nodes to elongate. This occurred via astrocyte Ca2+-mediated adenosine generation, targeting A2b receptors expressed in myelin sheaths which raised cyclic AMP levels in oligodendrocytes. This activated NKCC1 cotransporters present in the myelin of the paranodes and internodes, the expression of which was upregulated in the developing brain compared to adults. NKCC1 activation elevated the membrane conductance and reduced the length of internodal myelin sheaths. Thus, nodal dynamics may continuously tune information flow along myelinated axons and drive activity-dependent white matter plasticity.

Electrophysiological resting-state signatures link polygenic scores to general intelligence
Intelligence is associated with important life outcomes. Behavioral, genetic, structural, and functional brain correlates of intelligence have been studied for decades, but questions remain as to how genetics are related to trait expression and what intermediary role brain properties play. This study investigated these mediations in a representative sample of 434 individuals, comprising young and older adults. Polygenic scores (PGS) for intelligence were calculated. Resting-state EEG recordings were analyzed using graph theory quantifying functional connectivity across different frequencies. We tested whether global and local graph metrics like efficiency and clustering mediated the association between PGS and intelligence. PGS significantly predicted variance in intelligence and were related to frequency-specific graph metrics in areas predominantly located in parieto-frontal regions, which in turn were associated with intelligence. These findings, which are based on the first study linking PGS to intelligence using EEG-derived graph metrics, advance our understanding of the neurogenetics of intelligence.

Differential regulation of brain-specific molecular pathways is the reason for curcumin adult life-phase specific DAergic neuroprotection: Insights from ALSS Drosophila model of Parkinson disease
Curcumin (CU), a bioactive compound of turmeric, has been put forward as a golden molecule due to its anti-inflammatory, antioxidant, hepatoprotective, neuroprotective, and anti-cancer ability, as proven by research conducted over the decade and more. Our laboratory, developed an adult life stage specific (ALSS) Drosophila model of sporadic Parkinson disease (PD), and for first time demonstrated that dopaminergic (DAergic) neuroprotective efficacy of curcumin is limited to health phase viz. adult-young life stage and is absent during transition phase viz. adult senior life stages when PD set in. This observation suggests the limitation of curcumin as a therapeutic agent for late-onset disorders like PD. Further, our laboratory also demonstrated that despite curcumin ability to sequester oxidative stress during both the adult life stages, neuroprotection and brain dopamine replenishment is granted only in health stages but not in a vulnerable transition stage, which prompted to put forward the hypothesis that the molecular target(s) of CU, may be absent or inadequate in the transition stage of aging brain. With this insight, the current study was implemented to analyse the life stage-specific differential regulation of multiple molecular players of neuro-integral pathways in brain of ALSS Drosophila model of PD with curcumin intervention. It is discovered that curcumin-mediated health phase-specific neuroprotection underlies the correction of an altered expression of 1. dFOXO, GADD45, Puc of Bsk-dFOXO stress response pathway, 2. Mfn2 of Mitochondrial dynamics 3. CncC, GCLC, Prx 2540 -1,2, Jafrac1, Prx3 of Phase II antioxidant defense system pathway. Further, it is discovered that significant aging-associated naturally altered expression of certain molecular targets exists, that may contribute to the limitation of curcumin DAergic neuroprotective efficacy during the adult-transition stage. This knowledge will help in developing altered therapeutic strategies for PD as molecular targets of curcumin are conserved among fly, mice and human.

Postnatal reduction of eIF4E overexpression in D1-SPNs ameliorates KCNQ dysfunction, hyperexcitability and ASD-like behaviours.
An imbalance between the direct and indirect pathways of the striatum has been implicated in the pathophysiology of ASD, which corresponds with an increase in repetitive behaviours and hyperactivity. The ASD risk gene EIF4E promotes translation, and its overexpression in mice increases repetitive behaviours and hyperactivity. We used the eIF4E-transgenic mouse model of ASD to study cell-type specific disruptions in the direct and indirect pathways using fibre photometry, electrophysiology, conditional gene silencing, and behavioural analysis. We found that direct pathway SPNs activity increased during exploratory behaviour and identified D1-SPN hyperexcitability and reduced KCNQ channel function in striatal slices. Reduction of eIF4E specifically in the D1-SPNs of adult mice normalised KCNQ function, D1-SPN hyperexcitability and ameliorated repetitive and hyperactive behaviours. Our results highlight the critical role of eIF4E in ASD-associated motor behaviours, elucidate cell-specific mechanisms driving hyperactivity and provide new insight into potential therapeutic targets for ASD and other neurodevelopmental disorders. Overall, this study underscores the translational potential of modulating protein synthesis pathways to address core motor symptoms in ASD.

Functional organization of the neonatal thalamus across development depicted by functional MRI
The thalamus is a central component of the brain that is involved in a variety of functions, from sensory processing to high-order cognition. Its structure and function in the first weeks of extrauterine life, including its connections to different cortical and subcortical areas, have not yet been widely explored. Here, we used resting state functional magnetic resonance imaging data of 730 newborns from the developing Human Connectome Project to study the functional organization of the thalamus from 37 to 44 post-conceptual weeks. We introduce KNIT: K-means for Nuclei in Infant Thalamus. The framework employs a highly granular vector space of 40 features, each corresponding to functional connectivity to a brain region, using k-means clustering and uncertainty quantification through bootstrapping to delineate thalamic units. Although the different clusters showed common patterns of increased connectivity to the superior temporal gyrus, the parietal, and the frontal cortex, implying an expected decrease in specialization at that age, they also show some specificity. That is, a pulvinar unit was identified, similar to the adult thalamus. Ventrolateral motor and medial salience units were also highlighted. The latter appeared around 41 weeks of age, while the former showed at least from 37 weeks, but had a decrease in volume through age, replaced mostly by a dominant dorsal thalamic unit. We also observed an increase in clustering robustness and in hemispheric bilateral symmetry with age, suggesting more specialized functional units. We also found a burst in global thalamic connectivity around 41 weeks. Finally, we demonstrate the benefits of this method in terms of granularity compared to the more conventional winner-takes-all approach.

Simultaneous EEG-PET-MRI identifies temporally coupled, spatially structured hemodynamic and metabolic dynamics across wakefulness and NREM sleep
Sleep entails significant changes in cerebral hemodynamics and metabolism. Yet, the way these processes evolve throughout wakefulness and sleep and their spatiotemporal dependence remain largely unknown. Here, by integrating a novel functional PET technique with simultaneous EEG-fMRI, we reveal a tightly coupled temporal progression of global hemodynamics and metabolism during the descent into NREM sleep, with large hemodynamic fluctuations emerging as global glucose metabolism declines, both of which track EEG arousal dynamics. Furthermore, we identify two distinct network patterns that emerge during NREM sleep: an oscillating, high-metabolism sensorimotor network remains active and dynamic, whereas hemodynamic and metabolic activity in the default-mode network is suppressed. These results elucidate how sleep diminishes awareness while preserving sensory responses, and uncover a complex, alternating balance of neuronal, hemodynamic, and metabolic dynamics in the sleeping brain. This work also demonstrates the potential of EEG-PET-MRI to explore neuro-hemo-metabolic dynamics underlying cognition and arousal in humans.

Partial Wwox Loss of Function Increases Severity of Murine Sepsis and Neuroinflammation
Rationale: WW domain-containing oxidoreductase (WWOX) is a gene associated implicated in both neurologic and inflammatory diseases and is susceptible to environmental stressors. We hypothesize partial loss of Wwox function will result in increased sepsis severity and neuroinflammation. Methods: Wwox WT/P47T mice, generated by CRISPR/Cas9, and Wwox WT/WT mice were treated with intraperitoneal PBS vs LPS (10mg/kg) and euthanized 12 hours post-injection. Open Field Testing (OFT) and Murine Sepsis Severity Scores (MSS) were utilized to measure sickness behavior and sepsis severity, respectively. Brain tissue was analyzed using immunohistochemistry and PCR to measure neuroinflammation and apoptosis. Results: Wwox WT/P47T LPS mice demonstrated a more significant response to sepsis with an increase in sickness behavior, sepsis severity, gliosis, and apoptosis compared to Wwow WT/WT LPS littermates. Conclusions: Partial loss of Wwox function increases risk for severe sepsis and neuroinflammation. Given the susceptibility of WWOX to environmental stressors, this may be a target for future therapeutic interventions.

circAβ-a RNA encoded Aβ175--the hidden driver of β-amyloid plaque formation and deposition in sporadic Alzheimer's disease.
Mechanisms that trigger A{beta} production in sporadic Alzheimer's disease are still obscure. We recently reported the expression of a human circular RNA (circA{beta}-a) encoded A{beta} peptide precursor variant (A{beta}175). Presently, we demonstrated that AAV9 virus-expressed circA{beta}-a gave rise to extensive extracellular A{beta} plaque depositions and microglial activation in mouse brain; this recapitulates critical pathogenic hallmarks within a sporadic AD mouse model. Specifically developed antibodies detected robust endogenous A{beta}175 expression in HEK293 cells and hNSC-derived human neurons, underscoring the potential of A{beta}175 as a salient A{beta} precursor. Furthermore, we detected high levels of A{beta}175 oligomers in young-adult human brains. In intermediate and old-age human brain samples, accumulation of soluble A{beta}175 pentamers was reduced and A{beta}175 oligomers were components of most insoluble A{beta} plaques in older human brain. We propose a causal relationship between human circA{beta}-a RNA expression, dysregulation of A{beta}175 oligomer processing/aggregation and A{beta} plaque accumulation in sporadic AD.

Conditioning electrical stimulation enhances functional rewiring in a mouse model of nerve transfer to treat chronic spinal cord injury
Nerve transfer surgery is a state-of-the-art surgical approach to restore hand and arm function in individuals living with tetraplegia, significantly impacting daily life. While nearly a third of all individuals with chronic SCI may benefit from this intervention, variability in outcomes can limit the functional impact. A bedside-to-bench approach was taken to address the variable response of tetraplegic individuals to nerve transfer surgery. We used a hierarchical multiple factor analysis to evaluate the effects of conditioning electrical stimulation (CES) on outcomes in a mouse model of nerve transfer to treat chronic cervical spinal cord injury. We found that CES of donor nerves one week prior to nerve transfer surgery enhanced anatomical and functional measures of innervation of targeted muscles. Furthermore, CES increased the rate of recovery of naturalistic behavior. While the model has some limitations due to the small size of the rodent, our results support the use of CES as an effective approach to improve outcomes in clinical nerve repair settings.

Fentanyl blockade of K+ channels contribute to Wooden Chest Syndrome
Fentanyl is a potent synthetic opioid widely used perioperatively and illicitly as a drug of abuse. It is well established that fentanyl acts as a -opioid receptor agonist, signaling through Gi/o intracellular pathways to inhibit electrical excitability, resulting in analgesia and respiratory depression. However, fentanyl uniquely also triggers muscle rigidity, including respiratory muscles, hindering the ability to execute central respiratory commands or to receive external resuscitation. This potentially lethal condition is termed Wooden Chest Syndrome (WCS), the mechanisms of which are poorly understood. Here we show that fentanyl directly blocks a subset of EAG-class potassium channels. Our results also demonstrate that these channels are widely expressed in cervical spinal motoneurons, including those innervating the diaphragm. A significant fraction of these motoneurons is excited by fentanyl, concomitant with blockade of voltage-dependent non-inactivating K+ currents. In vivo electromyography revealed a persistent tonic component of diaphragmatic muscle activity elicited by fentanyl, but not morphine. Taken together our results identify a novel off-target mechanism for fentanyl action, independent of -opioid receptor activation, with a paradoxical excitatory effect that may underlie WCS. We anticipate these findings may inform the design of safer analgesics and generalize to other neuronal circuits implicated in fentanyl-related maladaptive behaviors.

Hypoxia-inducible factor 1 protects neurons from Sarm1-mediated neurodegeneration
The Sarm1 NAD+ hydrolase drives neurodegeneration in many contexts, but how Sarm1 activity is regulated remains poorly defined. Using CRISPR/Cas9 screening, we found loss of VHL suppressed Sarm1-mediated cellular degeneration. VHL normally promotes O2-dependent constitutive ubiquitination and degradation of hypoxia-inducible factor 1 (HIF-1), but during hypoxia, HIF-1 is stabilized and regulates gene expression. We observed neuroprotection after depletion of VHL or other factors required for HIF-1 degradation, and expression of a non-ubiquitinated HIF-1 variant led to even stronger blockade of axon degeneration in mammals and Drosophila. Neuroprotection required HIF-1 DNA binding, prolonged expression, and resulted in broad gene expression changes. Unexpectedly, stabilized HIF-1 prevented the precipitous NAD+ loss driven by Sarm1 activation in neurons, despite NAD+ hydrolase activity being intrinsic to the Sarm1 TIR domain. Our work argues hypoxia inhibits Sarm1 activity through HIF-1 driven transcriptional changes, rendering neurons less sensitive to Sarm1-mediated neurodegeneration when in a hypoxic state.