bioRxiv Subject Collection: Neuroscience's Journal

Ventral Striatal Dopamine Increases following Hippocampal Sharp-Wave Ripples
Leading theories suggest that hippocampal replay drives offline learning through coupling with an internal teaching signal such as ventral striatal dopamine (DA); however, the relationship between hippocampal replay and dopamine is unknown. Simultaneous recording of putative hippocampal replay events (dorsal CA1 sharp-wave ripples, SWRs) and fiber photometry of ventral striatal DA in mice revealed a significant increase in DA following SWRs, peaking ~0.3 s after SWRs. This result establishes for the first time a core theoretical requirement of offline learning in the mammalian brain.

Short-term memory capacity and chronic stress levels predict cognitive effort choice as a function of reward level and effort demand
Every day, we make choices about how much effort we are willing and able to use to achieve the outcomes we desire against the backdrop of constantly shifting effort demands and available rewards. While factors like visual short-term memory and chronic stress levels can predict responses to stable cognitive effort demands, we do not yet know whether they constrain one's choices of higher effort trials for larger rewards when task demands and potential outcomes shift over time. Here, we examined whether these factors predicted the choice to deploy cognitive effort given increasing effort demands and the tendency to deploy effort given shifting reward availability. Undergraduate participants first performed an online visual short-term memory task to assess capacity for visuospatial short-term memory. They then completed a series of choice trials where they could choose between high-effort, high-reward or low-effort, low-reward trials. In two blocks, we varied either the effort required on high-effort trials or the reward offered on both trial types. We found that visual short-term memory predicted the likelihood of choosing high-effort trials given shifting rewards, while chronic stress and everyday preferences for cognitively effortful strategies predicted the tendency to deploy increasing amounts of effort for a stable reward. Furthermore, participants' subjective reports show a strong focus on attentional processes, and balancing rewards and losses, when making decisions about how much effort to deploy. These findings shed light on distinct trait-level factors associated with cognitive effort choices given shifting demands and outcomes.

Functional Brain Mapping of Body Size Estimation Using a 3D Avatar
Background: Body size estimation, the ability to judge the size and shape of one's own body, is a key perceptual component of body image. However, its neural basis, and the basis for inter-individual differences in accuracy, remain poorly understood, partly due to limitations in existing assessment tools. Methods: We developed Somatomap 3D, an interactive fMRI-compatible task allowing participants to manipulate a rotatable 3D avatar by adjusting the size and shape of 26 individual body parts to match their perceived body. Twenty-eight healthy male and female adults completed the task during fMRI. Brain activity in a priori regions of interest from previous studies of body processing was modeled using a general linear model incorporating event-specific parameters and parametric modulators related to task performance. Inter-individual differences in body size estimation accuracy were calculated using multidimensional scaling of body part estimation errors, and scores were correlated with BOLD signal eigenvariates from regions of interest. Results: Task engagement was associated with significant activation in hypothesized body-selective and multisensory regions, including bilateral extrastriate body area, right fusiform body area, right superior parietal lobule, and bilateral premotor cortex. Multidimensional scaling identified a primary subdimension reflecting distortions in body part girths, which was significantly associated with neural responses in the superior parietal lobule. No other brain regions showed significant associations with inter-individual differences in estimation accuracy. Conclusions: These results suggest that body size estimation engages a distributed network of visual, motor, and parietal regions. Among these, only the superior parietal lobule showed a significant association with inter-individual variation in body size estimation accuracy for body part girths, supporting its role as a candidate neural substrate for altered body representation in psychiatric conditions such as eating disorders and body dysmorphic disorder.

Precision fMRI reveals densely interdigitated network patches with conserved motifs in the lateral prefrontal cortex
Dominant models of human lateral prefrontal cortex (LPFC) organization emphasize broad domain-general zones and smooth functional gradients. However, these models rely heavily on group-averaged neuroimaging, which can obscure fine-scale cortical features - especially in highly inter-individually variable regions like the LPFC. To address this limitation, we collected a new precision fMRI dataset from 10 individuals, each with approximately 2 hours of resting-state and 6 hours of task data. We mapped individual-specific LPFC networks using resting-state fMRI and tested network-level functional preferences using task fMRI. We found that individual LPFC organization differed markedly from group-average estimates. Individual maps showed more fragmented and interdigitated networks - especially in anterior LPFC - including novel conserved motifs present across individuals. Task fMRI revealed that distinct but adjacent networks support domain-specific processes (i.e., language, social cognition, episodic projection) versus domain-general control. Sharp functional boundaries were visible at the individual level that could not be observed in group data. These findings uncover previously hidden organizational principles in the LPFC and offer a framework for understanding how the LPFC supports flexible, complex cognition through a finely organized architecture.

Voltage Imaging with Periodic Structured Illumination
We utilize periodic structured illumination with pseudo-HiLo (pHiLo) image reconstruction for in vivo voltage imaging. We demonstrate reduced signal from out-of-focus cells, that contaminates voltage activity for in-focus cells of interest, with pHiLo compared to traditional widefield recordings taken with uniform illumination and pseudo-widefield (pWF) reconstructions. We discuss tradeoffs between signal-to-background ratio, signal-to-noise ratio and temporal resolution for pHiLo in the context of high-speed voltage imaging in awake mice.

Amyloid precursor protein dosage normalization rescues neurogenesis and Alzheimer's Disease phenotypes associated with Down Syndrome
Down Syndrome (DS) is the most abundant genetic form of mental retardation. It is caused by the triplication of partial or complete human chromosome 21 (HSA21). The molecular mechanisms causing it are not fully understood. Previous studies identified ''Down syndrome Critical Region'' (DSCR) genes that are essential or sufficient for the development of DS. However, these studies are largely inconclusive, due, in part, to the reliance on a small number of epidemiological cases. Amyloid precursor protein (APP) resides on HSA21 and is triplicated in DS. APP plays a role in developmental and post-natal neurogenesis, but is not thought to be part of the DSCR. The role of APP overdose in cortical malformation and cognitive impairments in DS is unknown. Mutations in APP cause familial Alzheimer's disease (FAD). However, whether APP overdose is sufficient for the development of Alzheimer's disease (AD) in DS is not fully understood. Here, we addressed the role of APP overdose in neuronal development and AD pathology. Using CRISPR/Cas9 gene editing, we eliminated one copy of APP from Down Syndrome-derived induced iPSCs DS APP(+/+/-) and examined the effect on neurogenesis, AD-related pathology and the expression levels of genes on HSA21 that are implicated in DS, neurodegeneration and inflammation.

Complementary BOLD- and ADC-fMRI explore the role of lateral superior colliculus in flicker fusion frequency
The transition from static to dynamic vision is encoded in the superior colliculus, as recently shown using blood-oxygen-level-dependent functional MRI (BOLD-fMRI) of the rat brain. Visual stimulation at higher frequency than the flicker fusion frequency threshold leads to continuity illusion and is associated with negative BOLD response in the visual cortex, triggered by the superior colliculus. In this paper, we explored this mechanism using fMRI of the rat brain with visual stimulation at low (1Hz) and high (25Hz) frequency. We compared responses between different brain regions (the dorsolateral geniculate nucleus of the thalamus, the medial and lateral parts of the superior colliculus, and the visual cortex), sexes, and field strengths (9.4T and 14T, with varying contributions from large vessels). Results confirmed distinct neural responses to low and high frequency stimulation and highlighted the role of the lateral part of the superior colliculus in the transition from static to dynamic vision. Finally, we evaluated the ability of apparent diffusion coefficient (ADC)-fMRI to detect response to visual stimulation without vascular contribution. We found significant ADC-fMRI response in the medial and lateral parts of the superior colliculus but also in the corpus callosum. Our results highlight the ADC-fMRI high spatial specificity and high sensitivity to white matter.

Sex-specific effects of chronic unpredictable stress on mitochondrial function in the HPA axis in mice
Stress, whether real or perceived, activates physiological and behavioral responses via the hypothalamic-pituitary-adrenal (HPA) axis and sympathetic nervous system activation. Under chronic stress, however, these adaptive responses become dysfunctional leading to pathological changes in behavior and health. Mitochondria are dynamic organelles essential for cellular energy production and for initiating glucocorticoid synthesis and release from adrenal glands during stress. Thus, mitochondria may represent a first line of response to environmental challenges. However, the effects of chronic stress on mitochondrial function within the HPA axis, particularly regarding sex differences, are unexplored. We exposed adult male and female C57BL6/J mice to four weeks of chronic unpredictable stress and examined behavioral and mitochondrial responses in the hypothalamus and adrenal glands -- two key HPA axis regions. As previous reports indicated sex differences in stress responsivity, we hypothesized that chronic stress would differentially impact mitochondrial respiration within HPA axis regions in a sex-specific manner. Chronic stress increased avoidance behavior in males and passive coping behavior in females, indicating sex-specific behavioral responses. In females, stress significantly decreased mitochondrial respiration in both the hypothalamus and adrenal glands, while males were not significantly affected. In males, stress increased adrenal expression of mitochondrial complex II protein, which may have served a compensatory role to preserve mitochondrial function. Mitochondrial respiration significantly correlated with behavioral measures in stressed animals, highlighting a relationship between metabolism and stress-induced impairments. These findings reveal sex-specific metabolic adaptations to chronic stress and suggest that females may be more vulnerable to stress-induced mitochondrial dysfunction within the HPA axis.

AI-assisted modeling of attentional control for intervention engagement
Cognitive training is one of the most used cognitive interventions, aiming for preventing or slowing cognitive decline in older adults. However, its effect is inconsistent, often due to the lack of effective engagement. Here we developed a novel AI-assisted multimodal framework, called Attentional Control Index using Digital measures (AID), which combines video-based facial expression analysis with ECG-derived heart rate variability (HRV) to assess the availability and allocation of attentional resources during cognitive training. Using two independent datasets of older adults at elevated risk for cognitive impairment, we demonstrated that AID accurately predicts both behavioral markers of engagement and cognitive outcomes from cognitive training. Additionally, we identified interpretable facial expressions and HRV features that reflect attentional control. These findings establish a robust, generalizable digital marker for assessing, and potentially in the future, enhancing effective engagement in cognitive training by focusing on the real-time dynamics of individual users' attentional control.

The atypical adhesion GPCR ADGRA1 controls hippocampal inhibitory circuit function
Neural circuits contain a diverse array of inhibitory interneurons that control information processing. The cell surface receptors and signaling pathways that modulate cell type specific inhibitory synaptic function are unclear. Here, we identify the atypical adhesion GPCR ADGRA1 as essential for hippocampal PV and SST inhibitory synaptic function. ADGRA1 is selectively enriched in hippocampal PV and SST interneurons and localizes to a subset of synapses. ADGRA1 deletion in PV and SST interneurons impairs inhibitory synaptic inputs onto Dentate Gyrus granule cells and generates deficits in learning and memory. ADGRA1 engages several downstream G proteins, notably G13, a pathway important for the establishment of hippocampal PV interneuron synaptic networks. These results identify an orphan receptor pathway selective for specific inhibitory synapse subtypes and expand our understanding of the signaling mechanisms that establish hippocampal inhibitory circuits.

Slow synaptic plasticity from the hippocampus underlies gradual mapping and fragmentation of novel spaces by grid cells
Animals construct internal "cognitive maps" of the world during navigation in spatial and non-spatial domains, with grid cells in the medial entorhinal cortex (MEC) playing a key role. This requires associating internal position estimates with external cues to reduce spatial uncertainty over time. However, how grid cell representations evolve in novel spaces to support map formation is unclear. To address this question, we longitudinally record grid cells with two-photon calcium imaging over 10 days as mice learn operant tasks in novel virtual linear tracks. We observe that spatial tuning of grid cells is present immediately in novel tracks but evolves as a significant fraction of spatial fields shift backward on a run-by-run basis, within and across days. Backward shifts are more prevalent and persistent in successful learners. The fields gradually stabilize across days, anchored by landmarks, suggesting a slow plasticity mechanism that results in an increasingly fragmented and stable map. The backward shifts partially reset daily, reflecting a slower consolidation timescale. We show that though individual fields of a cell shift differentially, co-active fields of co-modular grid cells shift together, indicating their coupled dynamics keep them on the same two-dimensional torus during this plastic period. Next, we build a simple entorhinal-hippocampal model that explains the diverse phenomena-grid field shifts, fragmentation, and increasing fidelity of the spatial map-and predicts slow Hebbian plasticity in the return hippocampal-to-entorhinal pathway. Finally, using ex vivo slice electrophysiology, we show that plasticity in an indirect hippocampus-to-MEC pathway correlates with spatial learning performance and could account for the hypothesized slow plasticity of the model. Together, our study provides multifaceted evidence of slow plasticity in synapses from the hippocampus to the MEC, elucidating the formation of stable and fragmented maps that combine internal and cue-driven positional estimates in rich environments, elucidating cognitive map formation during spatial learning.

Effort choices are sensitive to prior learning
Motivated behaviour relies on both learning and effort-based decision-making, yet these processes are often studied in isolation. We developed a novel paradigm combining probabilistic associative learning with effortful choices to better model real-world goal-directed behaviour. Participants (n=252) successfully learned stimulus-outcome associations, with marked individual differences in learning fidelity. Reward and loss stimuli differed in their ability to motivate effort, revealing a valence-specific asymmetry. Crucially, trial-by-trial effort choices were better predicted by participants subjective beliefs than by objective probabilities demonstrating that the willingness to exert effort is sensitive to prior learning. Notably, higher levels of anhedonia were associated with reduced willingness to engage in effortful action and a weaker alignment between learned value and action, suggesting a disruption in the integration of belief and motivation. These findings offer new insight into how value learning and effort expenditure interact, with implications for understanding motivational difficulties in psychiatric conditions.

Dual Mechanisms for Heterogeneous Responses of Inspiratory Neurons to Noradrenergic Modulation
Respiration is an essential involuntary function necessary for survival. This poses a challenge for the control of breathing. The preBotzinger complex (preBotC) is a heterogeneous neuronal network responsible for driving the inspiratory rhythm. While neuromodulators such as norepinephrine (NE) allow it to be both robust and flexible for all living beings to interact with their environment, the basis for how neuromodulation impacts neuron-specific properties remains poorly understood. In this work, we examine how NE influences different preBotC neuronal subtypes by modeling its effects through modulating two key parameters: calcium-activated nonspecific cationic current gating conductance (gCAN) and inositol-triphosphate (IP3), guided by experimental studies. Our computational model captures the experimentally observed differential effects of NE on distinct preBotC bursting patterns. We show that this dual mechanism is critical for inducing conditional bursting and identify specific parameter regimes where silent neurons remain inactive in the presence of NE. Furthermore, using methods of dynamical systems theory, we uncover the mechanisms by which NE differentially modulates burst frequency and duration in NaP-dependent and CAN-dependent bursting neurons. These results align well with previously reported experimental findings and provide a deeper understanding of cell-specific neuromodulatory responses within the respiratory network.

Enhanced synaptic excitation of VTA dopamine neurons in a mouse model of Alzheimer's disease
In Alzheimer's disease (AD) models, ventral tegmental area (VTA) dopamine neurons are intrinsically hyperexcitable, yet release less dopamine in projection regions, leading to dysfunctional downstream signaling. Synaptic transmission is broadly disrupted in AD, but it is not known to what extent altered excitatory and inhibitory inputs to the VTA influence dopaminergic activity and output. Here we describe enhanced synaptic excitation in dopamine neurons in the amyloid + tau-driven 3xTg-AD mouse model. AMPAR-mediated excitatory input was enhanced in a subset of connections, while GABAAR-mediated inhibition decreased as a function of dendritic atrophy. The strengthened excitation appeared to depend on presynaptic protein kinase C (PKC) activity as well as postsynaptic AMPA receptor enhancement. Biophysical modeling predicted that synaptic changes, in combination with altered dendritic morphology and previously described intrinsic hypersensitivity, produce increased firing and a steeper input-output relationship. These results suggest that AD pathology is associated with increased input-output gain in single dopamine neurons, which may function to maintain phasic dopamine signaling in early stages of axonal degeneration.

Neural components underlying successful free recall are specific to episodic memory
Episodic memory depends upon activity distributed across the brain. However, the activity underlying memory has largely been examined within single tasks in isolation. Thus it is unclear to what extent prior findings reflect task-general rather than memory-specific cognitive processes. Here we address this question using data from 371 patients recorded intracranially who performed a free recall task with encoding and retrieval phases alongside an arithmetic distractor phase. We ask whether neural decoders fit to predict behavior from one phase transfer to the others. Encoding-retrieval transfer exceeds both arithmetic-encoding and arithmetic-retrieval transfer and therefore cannot be explained solely by processes supporting arithmetic. We further detect transfer between arithmetic and retrieval but not between arithmetic and encoding. The brain-behavioral relations observed in these tasks thus do not merely reflect a single task-general factor of activity. We propose cross-task decoding as a method for identifying the neural factor structure underlying distinct cognitive processes.

Age- and alcohol-related differences in adolescent neurometabolite levels
Adolescence is a critical period for neurometabolite maturation as well as the onset of alcohol use, yet remains underexplored despite its significance for long-term neurodevelopmental outcomes. We used 3T proton magnetic resonance spectroscopy (MRS) to examine age- and alcohol-related associations with six neurometabolites in dorsal anterior cingulate cortex (dACC) that are involved in key neural functions: glutamate + glutamine (Glx), GABA plus macromolecules (GABA+), total N-acetylaspartate (tNAA), total choline (tCho), total creatine (tCr), and myo-inositol (mI). Participants were 84 adolescents (ages 17-22; 67% female) who completed MRS scans and self-reported past-60-day alcohol use via a modified Timeline Followback survey. Alcohol use variables included total drinking days, total binge drinking days, total number of drinks, and drinks per drinking day. Older adolescents had higher levels of GABA+, tNAA, tCho, and mI, and lower levels of Glx and Glx/GABA+; tCr was not associated with age. More alcohol use - specifically more drinking days, binge drinking days, and number of drinks - was associated with lower tNAA levels. Findings suggest age-related variation in dACC neurometabolites, which potentially reflect ongoing neuronal maturation, myelination, and shifts in excitatory and inhibitory neurotransmission. Lower tNAA among heavier drinkers may reflect associations between alcohol exposure and neuronal damage. Broader neurometabolic effects may emerge only with heavier or prolonged alcohol use.

Concurrent presentation of memory-related odors and sounds nullified sleep reactivation benefits
Reactivation of recently acquired memories during sleep supports their longevity. Reactivation can be biased during sleep using odors or sounds through a technique termed targeted memory reactivation (TMR). Here, we attempted to selectively weaken memories by reactivating them together with forgetting instructions. We delivered sounds to reactivate spatial memories and concurrent odors to reactivate instructions. Participants learned about the instructions in a Directed-Forgetting task performed with a list of to-be-remembered and to-be-forgotten words. One odor was linked with instructions to forget, one with instructions to remember, and a third was not assigned any meaning. During a nap, sounds previously linked with object-location learning were presented with these odors. Spatial recall was tested after sleep. Sounds produced a selective recall benefit for weakly encoded memories. However, results did not support the prediction that forgetting could be instilled by the concurrent forget odor. The encoding-strength-dependent benefit was greatest when sounds were presented together with the odor not assigned meaning, whereas the other two odors both disrupted sound-induced memory reactivation. We infer that remember and forget odors, due to the linked instructions and/or multiple learning episodes in the Directed-Forgetting task, evoked sleep-based retrieval that interfered with reactivation of spatial memories. Odors also induced a prolonged decline in sigma EEG power (12-16 Hz) that continued at least 10 s after odor offset. Overall, these findings highlight the complexity of memory consolidation during sleep when multiple memories and multiple cues are involved.

Butyrate preserves entorhinal-hippocampal spatial coding and blood brain barrier integrity in mice with depleted gut microbiome
Given the widespread and increasing consumption of oral antibiotics globally, understanding their impact on cognition through the gut-brain axis is crucial. We investigated whether broad-spectrum antibiotics disrupt spatial cognition by altering behavior, neural dynamics, brain metabolism, and blood-brain barrier integrity. Here we show that male mice receiving antibiotic-treated water display significant impairments in spatial memory tasks and abnormal encoding of space by entorhinal grid cells and hippocampal place cells. These cognitive deficits are accompanied by altered brain metabolism and blood-brain barrier permeability in the hippocampal formation. Remarkably, supplementation with butyrate, a key microbiome-derived metabolite, preserves spatial cognition, neural dynamics, and blood-brain barrier function despite antibiotic treatment. These findings reveal that gut microbiome depletion disrupts the hippocampal-entorhinal network underlying spatial cognition, while suggesting butyrate supplementation as a potential therapeutic approach to mitigate antibiotic-induced cognitive impairments.

Brain single-cell transcriptional responses to bexarotene-activated RXR in Alzheimer's disease model
Pharmacological activation of brain Retinoid X Receptors (RXRs) enhances cognition and facilitates amyloid-beta (A{beta}) clearance in Alzheimer's disease (AD) mouse models, partly by upregulating Apolipoprotein E (Apoe), a major AD genetic risk factor. However, the specific cellular contributions to these effects are unclear. Here, we used single-cell transcriptomic profiling to investigate cell subpopulation-specific responses to bexarotene, an RXR agonist, in APP/PS1 mice. Our analysis revealed that bexarotene activated cholesterol biosynthesis and lipid metabolism transcriptional programs in homeostatic astrocytes and oligodendrocytes. Astrocytes also upregulated neurodevelopmental genes, while oligodendrocytes and endothelial cells showed enhanced protein folding and cellular growth pathways. Bexarotene further modulated immune responses, promoting A{beta}-responsive signatures in disease-associated microglia and reactive astrocytes, while dampening pro-inflammatory responses in homeostatic microglia and endothelial cells. Furthermore, Apoe expression was significantly elevated across multiple cell types, especially in microglia and oligodendrocytes. Cell-cell communication analysis highlighted increased astrocyte-centered signaling, with APOE-driven pathways emerging as a prominent mediator. These findings clarify the cell-specific complexity of RXR-mediated regulation and underscore APOE as a central mediator of bexarotene's neuroprotective effects. This study provides mechanistic insights into RXR-targeted interventions, and supports APOE-associated pathways as promising therapeutic targets in AD.

Meningeal macrophages mask incision pain sensitization in male rats
Introduction: Meninges surrounding the brain and spinal cord house a variety of immune cell types including macrophages that express the CD206 mannose receptor. Here, we investigated whether CD206+ macrophages in the meninges play a role in regulating nociception and pain hypersensitivity. Methods: We selectively depleted CD206+ macrophages in the meninges around the lumbar spinal cord by intrathecal administration of anti-CD206 coupled to saporin, and determined the effects of CD206+ macrophage depletion on responses in naive rats and in those that had received a skin incision to the upper hindlimb. In addition, we used RNAseq to investigate transcriptional changes in lumbar meninges and dorsal root ganglia. Experiments were done in both male and female rats. Results: Depleting CD206+ meningeal macrophages did not alter basal responses in naive animals of either sex. By contrast depleting these cells after skin injury induced mechanical hypersensitivity in male rats, without changes in thermal sensitivity but had no effect in females. In male rats with skin incision injury, we found that the mechanical hypersensitivity induced by depleting CD206+ meningeal macrophages was reversed by administering the NMDAR antagonist, APV. In addition, the hypersensitivity was reversed by an enhancer of KCC2 function, CLP290. Unexpectedly, skin incision caused significant transcriptional changes in the meninges, but only in male rats. Conclusions: Taken together, our results indicate that while CD206+ meningeal macrophages do not regulate basal nociception in naive rats, after skin incision injury, these cells mask mechanical hypersensitivity in male rats only. Thus, we conclude that in a sex-dependent manner CD206+ meningeal macrophages prevent the spread of pain hypersensitivity after a minor injury. Importantly, the skin incision we used was comparable to that used in sham controls in numerous rodent studies of neuropathic pain. Our findings have, therefore, potentially broad implications for re-interpreting results from previous neuropathic pain research.

Gene augmentation therapy treats mature mice with complete congenital stationary night blindness (cCSNB), improving retinal function and visual acuity
Recombinant adeno-associated virus (rAAV) mediated gene therapy is an effective approach for targeting therapeutic genes to retinal photoreceptors. Complete congenital stationary night blindness (cCSNB) is a genetically heterogeneous inherited retinal disease caused by mutations in one of several genes, which are part of a large and interdependent depolarizing bipolar cell (DBC) signalplex required for normal synaptic signaling with photoreceptors. These genes include NYX, GRM6, TRPM1, GPR179, and LRIT3, and the cCSNB phenotype that results is characterized by abnormal low light vision, myopia, and nystagmus, but does not include retinal degeneration. Because of the non-progressive and recessive nature of cCSNB we investigated the potential of a gene augmentation approach in the mature retina to improve retinal function and visual acuity. We used a mouse model of cCSNB caused by the loss of LRIT3 to evaluate the efficacy of a single subretinal injection of rAAV expressing LRIT3 in either rods or cones, and the extent of restoration of retinal function and visual acuity. We show that gene augmentation by expressing LRIT3 in the rods of mature Lrit3-/- retinas restores function and scotopic visual acuity, and when expressed on cones, improves both photopic and scotopic visual acuity.

Development of a modified weight-drop apparatus for closed-skull, repetitive mild traumatic brain injuries in a mouse model
Repetitive mild traumatic brain injury (rmTBI) is a major contributor to long-term neurological dysfunction, yet many preclinical models lack precise control and quantification of biomechanical forces across impacts. We developed a reproducible, closed-skull mouse model of rmTBI using a custom-built weight-drop apparatus featuring a solenoid-based rebound arrest system, integrated high-speed videography, and accelerometry to track head kinematics during impact. Adult male and female mice received either a single impact or nine daily impacts. Linear and angular acceleration data were analyzed alongside behavioral and histological outcomes. Our apparatus delivered consistent impact and velocity forces with minimal inter-subject variability. Additionally, the animals exhibited consistent linear and angular acceleration when measured using high-speed video capture. Mice in the rmTBI model showed an increased return of righting reflex (RoRR) time, indicating cumulative effects of injury on return to consciousness. Behavioral testing revealed reduced performance of rmTBI-affected mice in an olfaction-mediated foraging task (buried food task), particularly at later timepoints, consistent with progressive olfactory impairment. Immunohistochemical analysis of Iba1 and CD68 in the brain demonstrated sex-dependent microglial activation, with males showing higher expression levels in single- and nine-impact models. Brain region-specific effects were most pronounced in the corpus callosum, neocortex, and olfactory tubercle. These findings underscore the importance of including sex as a biological variable in rmTBI research and support the utility of this model for probing injury thresholds, regional vulnerability, and potential therapeutic interventions in repetitive head trauma.

Humanized TfR1 and transferrin gene-replacement rats for in vivo evaluation of BBB transport
The transferrin receptor 1 (TfR1) transferrin (TF) axis plays a central role in iron homeostasis and has long been recognized as a promising route for delivering biologics across the blood brain barrier (BBB). We have developed a class of human-specific anti-TfR1 nanobodies (NewroBus) that exploit this transport pathway. However, the lack of cross-reactivity with rodent TfR1 limits the utility of standard animal models for preclinical testing. To overcome this challenge, we generated knock in (KI) rats in which the coding sequences of the endogenous Tfrc and Tf genes were replaced with human coding sequences, yielding animals that express human TfR1 and/or human TF under physiological control. Rats homozygous for both humanized alleles were viable and fertile, indicating that the human proteins can functionally replace their rodent equivalents. Nonetheless, these double homozygous rats exhibited erythropoietic abnormalities and tissue-specific alterations in iron distribution, characterized by decreased splenic and increased hepatic iron, suggesting incomplete functional compensation. In contrast, heterozygous rats showed only mild, subclinical hematologic changes (microcytosis and hypochromia). These findings demonstrate that the humanized TfR1 TF axis is compatible with life and iron regulation, albeit with varying degrees of compensation depending on gene dosage. Importantly, these KI rats provide a translationally relevant platform for evaluating pharmacokinetics, CNS penetration, and safety of human-specific BBB targeting therapeutics, including NewroBus-based biologics and other TfR1 mediated delivery strategies.

The Analgesic and Dissociative Properties of Ketamine are Separate and Correspond to Distinct Neural Mechanisms
Ketamine, a psychoactive medication, exerts both analgesic and dissociative effects. However, whether its analgesic effect stems from its dissociative properties is a topic of debate. Our study aimed to determine whether ketamine's analgesic and dissociative effects are supported by distinct neural mechanisms. In a within-subject, placebo-controlled study, 33 healthy volunteers were administered ketamine (0.4 mg/kg bolus followed by a continuous drip of 0.4 mg/kg/h) or saline during fMRI sessions where thermal pain was induced. Our results indicate that while ketamine significantly reduced thermal pain ratings and produced robust dissociative effects, these outcomes were not correlated. Neurally, ketamine reduced pain-related brain activations across a network of regions, including the insula and anterior cingulate cortex. Additionally, ketamine significantly diminished functional connectivity between default mode network regions, and this reduction was correlated with the intensity of dissociation. These findings suggest that ketamine's analgesic and dissociative effects are independent and mediated by distinct neural pathways.

Neuromodulation enhances dynamic sensory processing in spiking neural network models
Neuromodulators allow circuits to dynamically change their biophysical properties in a context-sensitive way. In addition to their role in learning, neuromodulators have been suggested to play a role in sensory processing at relatively fast timescales (less than a second), although the precise mechanisms at play are still not well understood. To assess the potential computational role of neuromodulators in sensory processing, we added a simple but flexible model of neuromodulation to spiking neural networks. These networks were then trained - with methods from machine learning - to carry out challenging sensory processing tasks. We find that this addition leads to a dramatic improvement in sensory processing in every task and configuration we tested. In particular, we find that without explicitly training for this, it decreases reaction times, a role that has been discussed for the cholinergic system. In a particularly challenging speech recognition in noise task, we find that the networks learn to make use of rapid dynamic gain control via excitability, an attentional mechanism akin to the "listening in the dips" strategy. This has been hypothesised to be a key element of human hearing allowing us to perform better in these conditions than even state-of-the-art machine learning systems. We conclude that neuromodulation does have the potential to play a significant computational role in fast sensory processing. In addition, our neuromodulated spiking neural networks are able to substantially increase performance at only a small cost to computational complexity, and may therefore be valuable for applications in energy-efficient "neuromorphic" computing devices.

ABCA7 deficiency exacerbates glutamate excitotoxicity in Alzheimer's disease mice -- a new pharmacological target for Glu-related neurotoxicity
Increasing attention has been directed towards the perturbation of glutamate (Glu) and {gamma}-aminobutyric acid (GABA) homeostasis during the pathogenesis of Alzheimer's disease (AD). The prevailing disequilibrium, stemming from hyperactivation of the glutamatergic system, culminates in progressive neuronal impairment and cognitive deterioration. This study aimed to elucidate the contributory role of the ATP-binding cassette transporter A7 (ABCA7), identified as the second most critical genetic determinant in AD, in glutamatergic-associated neurotoxicity. This endeavor sought to advance molecular comprehension of neurological disorders where Glu-GABA neurotransmission represents a pivotal pharmacotherapeutic target. Utilizing multi-omics approaches, we rigorously analyzed four distinct mouse models, both with and without APPtg and ABCA7 expression, to simulate varied pathological and ABCA7-deficient states. Our results revealed amyloid-{beta} (A{beta}) deposition as a catalyst for surging glutamatergic transmission. Notably, ABCA7 ablation exacerbated glutamatergic-induced neurotoxicity, attributed to diminished enzymatic activity related to neurotransmitter degradation and amplified expression levels of specific neurotransmitter transport proteins and receptor subunits, notably NMDA, AMPA, and GABAA. These findings furnish the first comprehensive description elucidating ABCA7's amplification of neurotoxic effects through modulation of Glu-GABA neurotransmission systems in neurodegenerative contexts, primarily mediated by lipid interaction. The evidence underscores ABCA7's imperative role in shaping future pharmacological strategies aimed at counteracting neurodegeneration precipitated by Glu-mediated neurotoxicity. This research advances the frontier for therapeutic exploration to ameliorate the deleterious neural consequences characteristic of neurodegenerative pathologies.

Processing and sectioning of organ donor spinal cord tissue for electrophysiology on acute human spinal cord slices
Acute spinal cord slice electrophysiology is a powerful technique used in preclinical basic science research to investigate sensory and motor neuron function and pathophysiology. A major barrier that stands between implementing these findings into effective clinical treatments is the translational gap between rodent models and human patients. To date, no methods or protocols describe how to prepare viable human spinal cord slices for acute electrophysiological recordings. To bridge this translational divide, we describe here a protocol for the extraction of spinal cord tissue from consenting human organ donors and the preparation and sectioning of this tissue for acute spinal cord slice electrophysiology. With the collaboration of a transplant service and licensed surgeon, tissue can be extracted in 30-50 minutes. Acute spinal cord slices can then be prepared in the laboratory by trained graduate students in 2.5-5 hours, depending on the amount of tissue and scope of experiments. Using a viability stain to confirm that spinal slices are of sufficient quality to proceed, slices can then be used for either patch-clamp recordings to study the excitability of individual neurons or for high-density multielectrode array recordings to study intact sensory circuits. Slices remain viable for 4 to 8 hours, providing ample time for investigating synaptic and circuit-level signalling dynamics, including the use of pharmacological agents to probe the roles of specific molecular targets. The approaches described here can be implemented to improve translational physiological research and as a human tissue-based preclinical drug target identification and validation assay.

Acute restraint stress impairs aversive memory retention but not memory formation
Stress can alter neurochemical signalling, affecting memory processing, but its underlying neurobiological mechanism remains unclear. Here, we investigate the effect of acute restraint stress (ARS) on long-term aversive memory retention in rats. We exposed the animals to either handling or ARS protocol and tested the rats in the plus-maze discriminative avoidance task (PMDAT). Also, we performed immunohistochemistry assays to unveil the effect of stress on neuronal activity. We found that ARS immediately after training does not impair memory formation but hinders retention. Training triggers a peak of C-fos 1 hour later and a delayed 18-hour increase of Zif268 in the dorsal CA1. The same does not occur when ARS is experienced immediately after training. We demonstrate the crucial role of Zif268 and C-fos signalling in maintaining PMDAT LTM. ARS is more relevant for memory retention than for memory formation of discriminative aversive memory.

Tau pathology reprograms glucose metabolism to support glutamatergic activity and excitatory imbalance
Alzheimer's disease (AD) is not only characterized by amyloid-beta (A{beta}) and tau pathology, but also by early and progressive disruptions in metabolism. Neuronal excitability is tightly coupled with metabolic demand, and aberrant excitatory activity -observed in AD patients and models- can drive changes in metabolism. While A{beta}-related metabolic impairments are well-described, less is known about how tau pathology independently contributes to altered metabolic states and excitatory tone. Therefore, we explored how tau pathology impacted whole body and CNS metabolism in mouse models of tauopathy, including the P301S PS19 and Tau4RTg2652 mice. In both models, hyperphosphorylated tau prevents the age-related decline in whole-body metabolism by preserving glucose tolerance and mitigating shifts in fuel utilization (respiratory exchange ratio; RER), suggesting the mice are glucose needy. Tau pathology also preserves diurnal rhythms in hippocampal interstitial fluid (ISF) glucose and lactate, likely due to increased neuronal activity during the active (dark) phase. Stable isotope-resolved metabolomics following 13C-glucose administration revealed that glucose is preferentially shunted toward glutamate synthesis- at the expense of GABA- highlighting a shift in excitatory/inhibitory balance. Interestingly, these changes were not explained by a primary deficit in synaptic mitochondria but by alterations in glycolytic flux. Adaptations were time of day dependent, where ISF glutamate rises after a glucose injection in the dark period but not the light period. This suggests increased glutamatergic activity may drive metabolic demand during the dark period when mice are more active. Together, these studies fundamentally highlight the important coupling between metabolism and excitability, which is disrupted by hyperphosphorylated tau, tau aggregation, and neurodegeneration. Understanding how tau pathology and metabolism interrelate provides a novel lens for the development of therapeutic targets in late stage AD.

Neural mechanisms and effects of acute stress on athletess' unfair decision-making behavior
Acute stress may disrupt decision - making by affecting cognitive and emotional processing. The behavioral and neural mechanisms of this in athletes are unclear. This study explored how acute stress impacts athletes' unfairness - related decision - making and its neural basis. Forty participants (20 university athletes and 20 non - athlete students) were randomly assigned to a stress group or a control group. Using functional near - infrared spectroscopy (fNIRS), the study monitored the prefrontal cortex (PFC) and temporoparietal junction (TPJ) blood oxygenation during an ultimatum game task after inducing acute stress via the Maastricht Acute Stress Test (MAST). Athletes under stress were more accepting of relatively unfair decisions than non - athletes. This was linked to lower activation in the frontal - eye areas (CH15), supramarginal gyrus (CH38), and somatosensory association cortex (CH67), and higher activation in the primary motor cortex (CH64) in athletes. The increase in acceptance efficiency correlated significantly with the reduced CH38 activation (Rho = - 0.425) and increased CH64 activation (Rho = 0.499). Long - term exercise likely enhances PFC - TPJ functional integration, helping athletes adopt adaptive strategies under acute stress. These findings offer insights for developing stress management and neuromodulation training programs for athletes.

Expression of the naked mole-rat transgene for Has2 improved health span in C57Bl/6 mice, but it did not attenuate age-related hearing loss.
The naked mole-rat (NMR) is renowned for being the longest-lived rodent, with a maximum lifespan of over 40 years. This exceptional longevity has been attributed to increased cytoprotective signaling, which has been partially ascribed to a major component of the NMRs extracellular matrix hyaluronan (HA), which has an unusually large molecular mass in this species. The HA molecular mass in the NMR is five to six times greater than in mice and humans. Mice expressing the transgene for NMR HA synthase 2 (nmrHas2), which is the enzyme that produces very high molecular mass HA (vHMM-HA), had improved health outcomes at an advanced age, such as improved mobility, grip strength, and reduced inflammation. Calorie restriction (CR) similarly improves healthspan in mice, and CR has also been shown to attenuate age-related hearing loss (AHL). Specifically, CR mitigates the effects of a single-nucleotide polymorphism (SNP) in the cadherin 23 (Cdh23) gene, which encodes a protein required for the stability of stereocilia on cochlear hair cells in mice and humans. Therefore, we hypothesized that AHL would be attenuated in nmrHas2+ mice. We performed auditory brainstem response testing on 3-month and 12-month-old mice with (nmrHas2+) and without (nmrHas2-) the NMR transgene. We observed AHL at 12 months of age in both nmrHas2+ and nmrHas2- mice, and AHL was not attenuated by nmrHas2 expression. This suggests that the cytoprotective effects of vHMM-HA work through a different pathway from CR, at least with respect to the inner ear.

Functional Connectivity in Self-limited Epilepsy with Centrotemporal Spikes (SeLECTS) Increases with Epilepsy Duration and Interictal Spike Exposure.
Objective: To determine the impact of epilepsy duration and interictal spikes on functional connectivity in children with Self-Limited Epilepsy with Centrotemporal Spikes (SeLECTS). Methods: Connectivity was calculated from electroencephalograms (EEGs) of 68 children with SeLECTS and 65 age and sex-matched controls using the weighted phase lag index. SeLECTS EEGs were categorized by epilepsy duration (shorter or longer than 6 months) to assess progressive connectivity changes. To investigate the impact of spikes on connectivity, 19 SeLECTS patients who underwent two EEGs were analyzed longitudinally, comparing those whose spikes persisted versus resolved over time. Analyses focused on connectivity during sleep. Results: Connectivity increased with epilepsy duration, being lowest in controls, intermediate in patients with shorter epilepsy duration, and highest in those with longer duration. Changes were initially greatest within the right occipital region and became more widespread with longer epilepsy duration. Longitudinally, patients with persistent spikes showed increasing connectivity over time, while those with spike resolution demonstrated decreasing connectivity, resulting in significant between-group differences. Conclusions: Functional connectivity in SeLECTS increases progressively with epilepsy duration and spike exposure, suggesting that ongoing spikes drive neural network alterations. Significance: Spikes are a potential treatment target to prevent progressive brain network disruption and preserve cognitive outcomes.

Drosophila males integrate song and pheromones usingcontext-specific strategies
Animals need to integrate sensory information from multiple modalities to interact with their environment and with others. In male Drosophila, multiple sensory cues modulate social behaviors such as courtship and aggression, but the strategies by which multimodal cues are combined to inform social behavior are not known. Here, we focus on how courtship song and taste cues are integrated to shape the social behavior of male flies. By combining cue manipulations with computational modeling, we assessed the individual and combined contributions of song and taste. Our results reveal three context-specific integration strategies. Overall social interactions were driven by a linear combination of song and taste. Aggression was driven by song, independent of taste cues. Courtship was controlled by a nonlinear integration of song and female taste cues, with female taste flipping the valence of song from suppressing to enhancing courtship. Our results show how context-specific integration strategies allow animals to recognize social scenarios and produce flexible, context-appropriate behaviors.

Young and old adult brains experience opposite effects of acute sleep restriction on the functional connectivity network
Chronic, long-term sleep loss is detrimental to brain health and cognitive ability. However, older adults are affected differently by acute, short-term loss of sleep than young and middle-aged adults. Older adults are more resilient to the effects of acute sleep loss and, depending on the cognitive domain, may be completely unaffected while younger adults suffer. To elucidate the brain network responses to sleep loss underlying these cognitive differences between age groups, we investigated the static and dynamic functional connectivity effects of sleep restriction (sleep limited to 3 hours) and how these effects differ between younger adults (20-30 years) and older adults (65-75 years). We found a functional connectivity subnetwork that was primarily strengthened in younger adults after sleep restriction but weakened in older adults after sleep restriction. Similar crossover interactions were consistently observed in further analyses of functional connectivity degree, modularity, and dynamic functional connectivity state fractional occupancy. Our findings demonstrate that the effect of sleep restriction on older adults is fundamentally different from younger adults. These results most strongly support the compensation theory of aging, which predicts a fundamental shift in the effects of sleep loss, rather than a mere dampening of the sleep benefits experienced by younger adults.

Restoring DSCAM expression rescues neuronal morphology and axon guidance deficits in Down syndrome
Down syndrome results from the triplication of human chromosome 21 and is the leading cause of intellectual disability. Down syndrome cell adhesion molecule (DSCAM) is located on human chromosome 21 and is overproduced in Down syndrome. DSCAM is a receptor for netrin-1 and plays a critical role in neural wiring during brain development. Using a Dscam gain-of-function mouse model and human induced pluripotent stem cell-derived cortical neurons, in combination with cellular, molecular, and behavioral approaches, this study aims to understand how DSCAM triplication and its subsequent excessive production contribute to changes in neural development and intellectual disability in Down syndrome. Analysis of morphological parameters revealed impaired neuronal development and loss of netrin-1-mediated axon guidance in mouse hippocampal pyramidal neurons overexpressing DSCAM. DSCAM overexpression also reduces interhemispheric connectivity in vivo. Furthermore, we find that DSCAM overexpression leads to impaired hippocampal-dependent learning and reduced anxiety in adult mice. Down syndrome human induced pluripotent stem cell-derived excitatory pyramidal neurons exhibit a similar phenotype: impaired morphological development and loss of netrin-1-mediated axon guidance. Remarkably, normalization of DSCAM in Down syndrome human induced pluripotent stem cell-derived neurons rescues many of these neuronal phenotypes, including reduced axon length and deficits in axon guidance. This study presents the first comprehensive cellular, molecular, and behavioural evidence that DSCAM is a significant contributor to multiple Down syndrome phenotypes, providing insight into a pathway for treatment. In summary, these results suggest that DSCAM plays an essential role in the development of neurons and neuronal networks, and its overproduction contributes to intellectual disability in Down syndrome.

Differential effects of HDAC inhibitors in the RhoI255d mouse model for autosomal dominant retinitis pigmentosa
Retinitis Pigmentosa (RP) is an inherited neurodegenerative disease which leads to loss of retinal photoreceptors and blindness. Histone deacetylases (HDAC) were previously found to be involved in photoreceptor cell death, and HDAC inhibitors have shown protective effects in animal models for autosomal recessive RP. However, whether HDAC inhibitors can protect photoreceptors in autosomal dominant RP (ADRP) remains unclear. Here, we utilized the recently generated human homologous RhoI255d/+ ADRP mouse model to investigate degenerative mechanisms and the therapeutic potential of HDAC inhibitors. To visualize photoreceptor HDAC activity, we applied an in situ HDAC activity assay on post-natal (P) day 20 wild type (WT) and RhoI255d/+ retina. Treatment with the HDAC class I/II inhibitor Trichostatin A and the HDAC class III inhibitor nicotinamide (NAM) suggested that most HDAC activity detected in RhoI255d/+ photoreceptors was related to class I/II isoforms. The therapeutic potential of different HDAC inhibitors, targeting different HDAC isoforms, was evaluated on organotypic retinal explants cultured under completely controlled conditions. HDAC inhibitors tested included SAHA (Vorinostat), MPT0G211, ACY-957, and NAM. Readouts comprised the TUNEL assay, immunostaining for activated calpain-2 and caspase-3, cone arrestin-3, and bromodeoxyuridine (BrdU)-labeling. Among the compounds tested, MPT0G211, targeting predominantly cytoplasmic HDAC-6, exhibited the strongest protective effect on both rod and cone photoreceptors. Remarkably, ACY-957, inhibiting nuclear HDAC-1/-2, at higher concentration induced both photoreceptor cell death and cell proliferation. High levels of NAM, blocking mitochondrial and nuclear HDACs, caused selective rod cell death, without affecting cones. All HDAC inhibitors tested had no or only minor effects on neurons of the inner retina. Our study highlights the complexity of HDAC activity during photoreceptor neurodegeneration and cautions against the use of unspecific inhibitors. At the same time, it showcases important differences between rod and cone photoreceptors and suggests especially HDAC-6 as a potential target for future therapy development.

Modulation of tactile sensitivity in the lower limbs during goal-directed movements
Tactile sensitivity drops in a moving than static limb due to a combination of central, predictive mechanisms and peripheral effects. This suppression is dynamically modulated during movement, as shown during upper-limb actions, yet little is known about its implication during complex lower-limb movements. We investigated tactile sensitivity during naturalistic kicking by delivering vibrotactile probe stimuli to the balancing and kicking feet at different movement phases. In Experiment 1, participants kicked a suspended ball while tactile sensitivity was probed at movement onset, mid-swing, ball con-tact, and after-contact. Results revealed distinct modulation patterns in each foot. When transitioning from bipedal to unipedal stance, tactile processing at the balancing foot was particularly suppressed but at the kicking foot it improved, suggesting concurrent modulation across the two legs depending on their motor function. Tactile sensitivity remained rather invariant at other time points, but was strongly suppressed on the kicking foot at the moment of ball contact. The strength of this suppression correlated with kicking speed, which could reflect either stronger predictive control or stronger peripheral processes that mask the vibrotactile probe. To test these, a new set of participants held their foot still while a ball collided with it at high or low speed. Suppression was greater with faster ball contacts, revealing that peripheral processes can modulate tactile processing. These findings show that lower-limb tactile sensitivity during goal-directed leg movements can be concurrently modulated across the legs, presumably reflecting an interplay between central sensorimotor processes guiding the movement and peripheral processes affecting sensitivity.

The gliotransmitter S100β regulates synaptic plasticity in the visual cortex
Synaptic plasticity is a fundamental mechanism of memory storage in the brain. Among the various rules governing changes in synaptic strength, Spike Timing-Dependent Plasticity (STDP) stands out for its strong physiological relevance in vivo. Ubiquitous across brain regions and neuronal types, STDP is a complex and multifactorial process influenced by factors such as neuromodulation, extracellular calcium levels, and activity patterns. However, one relatively understudied factor is the role of astrocytes, despite their well-established involvement in regulating synaptic transmission and neuronal excitability through gliotransmitter release. While some factors have garnered significant attention, others, like S100{beta}, have remained relatively underexplored despite their potential importance in regulating synaptic plasticity. S100{beta} is a calcium-binding protein, allowing it to influence extracellular Ca2+ concentration and potentially all Ca2+-dependent plasticity processes. Building on our previous research in the visual cortex, where we examined the regulation of neuronal excitability by S100{beta}, we chose to further investigate the role of astrocytes and S100{beta} in synaptic plasticity at layer 2/3-layer 5 synapses in the visual cortex. We demonstrated that S100{beta} is an important gliotransmitter to consider, capable of regulating long-term potentiation.

Sex-dependent effects of Neuroligin-2 absence on wake/sleep architecture and electrocorticographic spectral and multifractal activities
Neuroligin-2 (NLGN2) is a synaptic adhesion protein shaping GABAergic neurotransmission that has been linked to neurodevelopmental disorders. The absence of NLGN2 in male mice increases time spent awake, decreases time spent in slow wave sleep, and alters electrocorticographic (ECoG) activity. Whether the lack of NLGN2 also impacts wake/sleep states in females remains to be established. We aimed to compare sexes for the effects of NLGN2 absence on the wake/sleep architecture, spectral and multifractal ECoG activities. Nlgn2 knockout (KO) mice and wild-type littermates were implanted with ECoG electrodes, and ECoG signals were recorded for 48 hours. Nlgn2 KO mice of both sexes spent more time awake and less time in slow wave and paradoxical sleep, with KO males spending less time in paradoxical sleep during both the light and dark periods compared to wild-type males (difference only during the dark in females). Nlgn2 KO animals displayed longer wakefulness and shorter slow wave and paradoxical sleep episodes, and KO males (but not females) showed more wake and slow wave sleep episodes during the light period. Also, mutant animals (both sexes) showed widespread differences in wake/sleep spectral activity when compared to wild-type mice, notably a slower theta peak frequency during paradoxical sleep. The most prominent Hurst exponent was significantly increased in Nlgn2 KO animals during all states, and Hurst exponents were less dispersed during paradoxical sleep only in KO females. The findings indicate that effects of NLGN2 absence on wake/sleep phenotypes differ between sexes, and could help understanding sleep disturbances in neurodevelopmental disorders.

Tau controls NMDA receptor trafficking during homeostatic synaptic plasticity
Homeostatic synaptic plasticity is essential for maintaining stable neural circuit function by preventing excessive neuronal excitation or inhibition. Chronic perturbation of neuronal activity triggers a compensatory modulation of the number of -amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) and N-methyl-D-aspartate (NMDA) glutamate receptors at the excitatory synapses. Previous research has primarily focused on AMPA receptors, yet the molecular mechanisms regulating the trafficking of NMDA receptors during homeostatic synaptic scaling remain unclear. Here we identify the microtubule-associated protein Tau as an essential molecule that mediates the synaptic upscaling of GluN2B-containing NMDA receptors during prolonged synaptic inactivity. Chronic activity blockade increases Tau phosphorylation at Ser-235 by cyclin-dependent kinase 5 (Cdk5), enhancing its interaction with and retention of active Fyn tyrosine kinase in the postsynaptic compartment. This promotes the phosphorylation of GluN2B at Tyr-1472, subsequently stabilising the expression of NMDA receptors on the neuronal plasma membrane. Finally, we showed that Tau pathology and disease-associated mutations in Tau and the GluN2B carboxyl-terminal tail disrupt the homeostatic synaptic upscaling of NMDA receptors following chronic neuronal silencing. Together, our findings identify a physiological role for Tau in homeostatic synaptic plasticity, the perturbation of which can lead to neuronal hyperexcitation, seizures and excitotoxic cell death.

Sleep-like Slow Waves During Wakefulness Mediate Attention and Vigilance Difficulties in Adult Attention-Deficit/Hyperactivity Disorder
Background: Attention-Deficit/Hyperactivity Disorder (ADHD) is characterised by behavioural variability and heightened inattention associated with increased mind wandering (MW) and mind blanking (MB). Individuals with ADHD frequently experience sleep disorders and excessive daytime sleepiness, suggesting interactions between attention and arousal systems. Research examining brain activity using electroencephalography (EEG) has demonstrated that sleep-like slow waves (SW) during wakefulness are linked to inattention in neurotypical individuals, particularly following sleep deprivation, yet their role in ADHD remains unclear. This study investigated whether individuals with ADHD present with altered waking SW distribution compared to neurotypical controls and whether SW explain attentional difficulties in ADHD. Methods: Adults with (n = 32) and without ADHD (n = 31) completed a sustained attention task while EEG recorded brain activity. Mental state probes (on-task, MW, MB) were embedded within the task. Sleep-like SW reflect a slowing of cortical activity and was detected from EEG activity. Omission/commission errors, reaction time (RT), RT variability, mental state reports and subjective sleepiness were analysed. Mediation analysis examined whether SW density explained ADHD-related performance differences. Results: Individuals with ADHD exhibited more commission errors, MW and MB, and higher SW density (SW/min), particularly over parieto-temporal electrodes. Increased SW density correlated with higher omission errors, slower RTs, greater RT variability, and elevated sleepiness ratings. On-task reports were negatively correlated with SW density. Mediation analysis revealed that SW density significantly accounted for ADHD-related attentional difficulties. Conclusions: Wake SW may explain attentional difficulties in ADHD, providing a potential mechanistic link between sleep disturbances and attentional fluctuations.

Partial recurrence enables robust and efficient computation
Neural circuits are sparse and bidirectional. Meaning that signals flow from early sensory areas to later regions and back. Yet, between connected areas there exist some but not all pathways. How does this structure, somewhere between feedforward and fully recurrent, shape circuit function? To address this question, we designed a new recurrent neural network model in which a set of weight matrices (i.e. pathways) can be combined to generate every network structure between feedforward and fully recurrent. We term these architectures partially recurrent neural networks (pRNNs). We trained over 25,000 pRNNs on a novel set of reinforcement learning tasks, designed to mimic multisensory navigation, and compared their performance across multiple functional metrics. Our findings reveal three key insights. First, many architectures match or exceed the performance of fully recurrent networks, despite using as few as one-quarter the number of parameters; demonstrating that partial recurrence enables energy efficient, yet performant solutions. Second, each pathway's functional impact is both task and circuit dependent. For instance, feedback connections enhance robustness to noise in some, but not all contexts. Third, different pRNN architectures learn solutions with distinct input sensitivities and memory dynamics, and these computational traits help to explain their functional capabilities. Overall, our results demonstrate that partial recurrence enables robust and efficient computation - a finding that helps to explain why neural circuits are sparse and bidirectional, and how these principles could inform the design of artificial systems.

High frequency oscillations and the 1/f slope vary across a spectrum of depression severity
Depression is a highly prevalent mental disorder that impacts individual functioning, societal productivity, and quality of life. It is associated with disrupted neural activity (e.g., balance of excitation-inhibition) across networks implicated in emotional processing, such as between prefrontal and limbic regions. High frequency oscillations measured with electroencephalography (i.e., beta and gamma rhythms) differ between healthy individuals and those with depression, and predict treatment outcomes following pharmacological intervention. However, to date research has focussed on binary comparisons between individuals with a clinical depression diagnosis relative to healthy control populations, providing limited insight into how these measures may shift as a function of illness severity. To establish the utility of EEG measures as potential biomarkers for depression, an improved understanding across the spectrum of symptom profiles is required. Here, we aimed to bridge this gap and investigate changes in high frequency beta and gamma oscillations and the 1/f slope in resting-state EEG across a spectrum of mild to severe depression symptom presentations. In line with expectations, we demonstrate graded alterations to gamma and beta power and the 1/f slope across a spectrum of depression severity. Our findings provide critical new insights into the neurophysiological signature of depression symptoms, and highlight the utility of EEG markers to inform future precision psychiatry approaches to more effectively assess and treat depression.

View, engage, predict: enhancing brain-behavior mapping with naturalistic movie-watching fMRI
Most brain-behavior mapping studies rely on resting-state functional connectivity (FC), but this approach has known accuracy limits and can be outperformed by movie-watching FC. Here, we present a novel deep neural network framework to predict cognitive scores and sex from FC during naturalistic movie viewing, and examine how movie content and its ability to synchronize brain activity across individuals relate to prediction performance. We show that FC from movie-watching generally outperforms resting-state FC - even when compared to five times more temporal data - with sensory and higher-order brain networks emerging as the most important for prediction. Using both static and sliding-window dynamic FC approaches, we find that higher cognitive prediction accuracy is significantly associated with greater inter-subject synchrony and the duration of human faces and voices in the movies; these effects were not found for sex prediction. This work underscores the promise of naturalistic movie viewing as a powerful tool for probing individual differences in the brain and revealing neural underpinnings of human behavior.

PV - Oligodendrocyte Interactions in the Infralimbic Cortex Promote Extracellular Plasticity after Safety Learning
Safety learning is mediated by the infralimbic region (IL) of the medial prefrontal cortex, but its cellular mechanisms are poorly understood. Here we show that safety learning improves cognitive flexibility in the long-term, which is associated with recruitment of oligodendrocyte progenitor cells to a satellite position at parvalbumin (PV) interneurons in the IL and their maturation into oligodendrocytes (OLs), as well as a decrease in perineuronal nets (PNNs) surrounding PVs paired with satellite OLs. Using scRNA transcriptomic data mining, we demonstrate that immature OLs primarily express PNN assembly genes, whereas mature OLs express PNN degradation enzymes. We then demonstrate that inhibiting IL PVs during safety learning prevents safety- induced cognitive flexibility, satellite OL maturation, and PNN degradation around IL PV. Thus, we propose that safety learning drives a novel form of neuroglial plasticity that helps degrade PNNs around PV interneurons via OL recruitment and maturation, thereby shaping IL long-term activity.

A unifying theory of receptive field heterogeneity predicts hippocampal spatial tuning
Neural populations exhibit receptive fields that vary in their sizes and shapes. Despite the prevalence of such tuning heterogeneity, we lack a unified theory of its computational benefits. Here, we present a framework that unifies and extends previous theories, finding that receptive field heterogeneity generally increases the information encoded in population activity. The information gain depends on heterogeneity in receptive field size, shape, and on the dimensionality of the encoded quantity. For populations encoding two-dimensional quantities, such as place cells encoding allocentric spatial position, our theory predicts that both size and shape receptive field heterogeneity are necessary to induce information gain, whereas size heterogeneity alone is insufficient. We thus turned to CA1 hippocampal activity to test our theoretical predictions - in particular, to measure shape heterogeneity, which has previously received little attention. To overcome limitations of traditional methods for estimating place cell tuning, we developed a fully probabilistic approach for measuring size and shape heterogeneity, in which tuning estimates were strategically weighted by explicitly measured uncertainty arising from biased or incomplete traversals of the environment. Our method furnished evidence that hippocampal receptive fields indeed exhibit strong degrees of size and shape heterogeneity, abiding by the normative predictions of our theory. Overall, our work makes novel predictions about the relative benefits of receptive field heterogeneities beyond our application to place cells, and provides a principled technique for testing them.

Selective targeting of mutant huntingtin intron-1 improves rescue provided by antisense oligonucleotides
Huntington's disease (HD) arises from the toxic gain of function caused by a CAG expansion in the coding region of the HTT gene. HD is increasingly appreciated to emerge from multiple pathogenic processes, including somatic instability in mutant HTT's (mHTT) CAG repeat tract, which leads to diverse deleterious consequences. These include the alternative processing of HTT pre-mRNA to generate the HTT1a transcript that encodes the very toxic, mHTT isoform referred to as HTT1a. We set out to compare the efficacy and safety of allele-selective lowering of mHTT compared to non-allele-selective lowering using antisense oligonucleotides (ASOs) in heterozygous HttQ111 (Q111) mice. We developed a mutant specific ASO (MutASO) targeting Htt intron-1 that selectively reduced mutant full-length HTT, as well as HTT1a, in the brains of Q111 mice. Compared to the rescue provided by a pan-allele-targeting ASO (PanASO) that lowers wild-type HTT and full-length mHTT (sparing HTT1a), the MutASO essentially eliminated aggregate formation, and provided marked protection from transcriptional dysregulation in HD knock-in mice. Thus, by targeting the ASO to the region upstream of the cryptic polyadenylation sites required to generate the HTT1a transcript, our allele-selective MutASO potently reduced HTT1a protein levels. Here, our findings advocate that HTT1a may have a disproportionate impact on aggregate formation and transcriptional dysregulation and that lowering the levels of HTT1a could provide benefit when designing HTT-lowering based therapeutic strategies for HD.

Age-associated microglia populations identified from several single cell transcriptome data
Microglial senescence contributes to inflammation and various neurodegenerative diseases. Recent single-cell transcriptome data have revealed age-associated microglial substates (AAMs) and their potential roles in the development of neurodegenerative diseases. However, the characteristics identified in each study are not necessarily consistent. Here, we perform an integrative analysis of seven previously reported single-cell RNA-seq and four single-nucleus RNA-seq datasets of microglia from young and aged mouse brains. We identify four common AAMs across all datasets and two dataset-specific AAMs. Each AAM exhibits distinct transcriptomic patterns, including alterations in ribosomal genes, Apoe, cytokine genes, interferon-responsive genes, and phagocytosis-related genes. Time-series and pseudotime analyses indicate that the production of AAMs is initiated by the upregulation of ribosomal genes. Predictions based on single-cell transcriptomic data of age-associated manipulations reveal an increase in specific AAMs in a stimulation-type-dependent manner. We also identify similar AAMs in human brains. Altogether, our large-scale integrative analysis highlights promising age-associated microglial populations, which may serve as novel therapeutic targets for age-related neurodegenerative diseases.

sox17 mutagenesis reveals microglia can be impacted by genetic maternal effects
Embryonic development is precisely shaped by maternal and zygotic factors. These maternal factors exert their influence through maternal effects, a phenomenon where an offspring's phenotype is determined, at least in part, by the mother's environment and genotype. While environmental maternal effects can cause phenotypes that present both early and later in life, genetic maternal effects generally induce phenotypes in the earliest embryonic stages. Here, we reveal a genetic maternal effect that influences the development of cells that arise after early embryogenesis, highlighting that specific cell types can be susceptible to late-onset genetic maternal effects. Using zebrafish to study microglia, the resident immune cells of the brain, we identified a mutation in sry-related HMG box gene-17 (sox17) that exhibits a maternal effect phenotype that presents as a reduction of microglia in the brain and precursors in the yolk sac. We demonstrate that sox17 is expressed in microglia and their yolk sac precursors and is maternally-loaded. We show that sox17 restoration via embryonic injection reverses the maternal effect on microglia and yolk sac cells in sox17 mutants. To identify additional genes interacting with sox17, we nominated genes from scRNA sequencing analysis of mouse embryonic microglia to perform a genetic screen using CRISPR mutagenesis and a custom-built robot that captures confocal images of the zebrafish brain in high-throughput. This screen identified f11r.1, gas6, and mpp1 as modifiers of microglia abundance in the embryonic brain, which we demonstrated are also expressed in zebrafish microglia. Transcriptional and mutant analyses with these new modifiers suggest that sox17 positively regulates mpp1 transcription. These results demonstrate that microglia are susceptible to genetic maternal effects, in addition to their known sensitivity to environmental maternal effects. Our findings reveal a late-onset phenotype associated with the maternal genotype, expanding the recognized impact of genetic maternal effects beyond initial embryo viability and into long-term vigor.

The Crunchometer: A Low-Cost, Open-Source Acoustic Analysis of Feeding Microstructure
Elucidating the neuronal circuits that govern appetite requires a detailed analysis of the microstructure of solid food consumption. A significant barrier in this field is that existing techniques for monitoring feeding are either prohibitively expensive, limiting their use, or lack the high temporal resolution necessary to align feeding events with neuronal activity. To overcome these limitations and democratize this technology, we developed the Crunchometer, an open-source sound-based system that utilizes a cost-effective condenser microphone and video recordings, along with two mathematical methods (supervised thresholding and an unsupervised Support Vector Machine, SVM), to precisely capture bite sounds with unprecedented temporal resolution and built a feeding ethogram for both Chow and High-Fat Diet (HFD) pellets. While human observers tend to estimate longer, more frequent feeding bouts, our automated methods more precisely and reliably detect the start and end times of most feeding bouts. In consequence, both automated methods fragmented feeding bouts more frequently than human observers. We demonstrate the Crunchometer's utility by monitoring feeding patterns across different energy states, hunger (fasted), and satiety, and by characterizing the pharmacological effects of the anti-obesity drug semaglutide. This revealed that semaglutide not only suppresses solid food intake but also decreases the preference for HFD pellets. Additionally, we differentiate the genetically-evoked gnawing from consummatory feeding behaviors involving GABAergic neurons in the Lateral Hypothalamus (LH). Importantly, the Crunchometer integrates seamlessly with in vivo electrophysiology and calcium imaging in freely behaving mice. The Crunchometer, paired with recordings of LH activity, revealed the presence of meal-related neurons that monitor the entire meal, rather than just individual feeding bouts. Microendoscopes and calcium imaging on Vgat-IRES-cre and Vglut2-IRES-cre mice further suggest that GABA neurons in LH (but not glutamatergic neurons) are also strongly modulated by eating a solid food pellet. Notably, the acts of licking liquid sucrose and eating solid food activate distinct sets of neurons. Its compatibility with electrophysiology and calcium imaging makes the Crunchometer an ideal tool for elucidating the neuronal correlates of feeding behavior for solid foods.

Inhibitory columnar feedback neurons are required for motion processing in Drosophila
Visual motion information is essential to guiding the movements of many animals. The establishment of direction-selective signals, a hallmark of motion detection, is considered a core neural computation and has been characterized extensively in primates, mice and fruit flies. In flies, the circuits that produce direction-selective signals rely on feedforward visual pathways that connect peripheral visual inputs to the dendrites of the ON and OFF-direction selective cells. Here we describe a novel role for feedback inhibition in motion computation. Two GABAergic neurons, C2 and C3, connect to neurons upstream of the direction-selective T4 and T5 cells and blocking C2 and C3 affects direction selectivity in T4/T5. In the ON pathway, this is likely achieved by C2-mediated suppression of responses in the major T4 input neuron Mi1. Together, C2 and C3 suppress responses to non-preferred stimuli in both T4 and T5. At the behavioral level, feedback inhibition temporally sharpens responses to ON stimuli, enhancing the flys ability to discriminate visual stimuli that occur in quick succession. GABAergic inhibitory feedback neurons thus constitute an essential component within the circuitry that computes visual motion.

Parametric models for predicting nonstationary spike-spike correlations with local field potentials
Correlations between the spiking of pairs of neurons are often used to study the brain's representation of sensory or motor variables and neural circuit function and dysfunction. Previous statistical techniques have shown how time-averaged spike-spike correlations can be predicted by the time-averaged relationships between the individual neurons and the local field potential (LFP). However, spiking and LFP are both nonstationary, and spike-spike correlations have nonstationary structure that cannot be accounted for by time-averaged approaches. Here we develop parametric models that predict spike-spike correlations using a small number of LFP-based predictors, and we then apply these models to the problem of tracking changes in spike-spike correlations over time. Parametric models allow for flexibility in the choice of which LFP recording channels and frequency bands to use for prediction, and coefficients directly indicate which LFP features drive correlated spiking. Here we demonstrate our methods in simulation and test the models on experimental data from large-scale multi-electrode recordings in the mouse hippocampus and visual cortex. In single time windows, we find that our parametric models can be as accurate as previous nonparametric approaches, while also being flexible and interpretable. We then demonstrate how parametric models can be applied to describe nonstationary spike-spike correlations measured in sequential time windows. We find that although the patterns of both cortical and hippocampal spike-spike correlations vary over time, these changes are, at least partially, predicted by models that assume a fixed spike-field relationship. This approach may thus help to better understand how the dynamics of spike-spike correlations are related to functional brain states. Since spike-spike correlations are increasingly used as features for decoding external variables from neural activity, these models may also have the potential to improve the accuracy of adaptive decoders and brain machine interfaces.

Methylomic signatures of tau and amyloid-beta in transgenic mouse models of Alzheimer's disease neuropathology
Alzheimer's disease (AD) is characterized by progressive neurodegeneration driven by tau and amyloid-{beta} (A{beta}) pathology, although the underlying molecular mechanisms remain incompletely understood. Emerging evidence implicates a role for epigenetic modifications, particularly altered DNA methylation (DNAm), in AD pathogenesis. However, few studies have comprehensively investigated DNAm in experimental models. Here, we profile DNAm dynamics in two widely used transgenic mouse models of tau (rTg4510) and A{beta} (J20) neuropathology, focusing on variation in the entorhinal cortex and hippocampus. Using reduced representation bisulfite sequencing (RRBS) and methylation arrays across multiple disease stages, we identified widespread DNAm alterations associated with genotype and neuropathological burden in both models. In rTg4510 mice, tau accumulation was linked to extensive DNAm remodeling at genes involved in neuronal plasticity, apoptosis, lipid metabolism, including Dcaf5, Creb3l4, and As3mt. J20 mice exhibited more modest changes annotated to immune-related genes, notably at Grk2, Ncam2, and Prmt8. Of note, tau-associated DNAm changes were more consistent across brain areas than those associated with A{beta} pathology. Comparison with DNAm data from human studies revealed that a subset of DNAm sites mirrored those observed in the human AD cortex, including hypermethylation at Ank1 and Prdm16 in rTg4510 mice. These findings provide evidence for early, pathology-associated epigenetic alterations in AD, highlight both shared and distinct DNAm signatures of tau and A{beta}, and offer insight into molecular mechanisms that may precede overt neurodegeneration. Our work underscores the utility of epigenomic profiling in transgenic models and provides a foundation for identifying novel targets for early intervention in AD.

A sensitive orange fluorescent calcium ion indicator for imaging neural activity
Genetically encoded calcium indicators (GECIs) are vital tools for fluorescence-based visualization of neuronal activity with high spatial and temporal resolution. However, current highest-performance GECIs are predominantly green or red fluorescent, limiting multiplexing options and efficient excitation with fixed-wavelength femtosecond lasers operating at 1030nm. Here, we introduce OCaMP (also known as O-GECO2), an orange fluorescent GECI engineered from O-GECO1 through targeted substitutions to improve calcium affinity while retaining the favorable photophysical properties of mOrange2. OCaMP exhibits improved two-photon cross-section, responsiveness, photostability, and calcium affinity relative to O-GECO1. In cultured neurons, zebrafish, and mouse cortex, OCaMP outperforms the red GECIs jRCaMP1a and jRGECO1a in sensitivity, kinetics, and signal-to-noise ratio. These properties establish OCaMP as a robust tool for high-fidelity neural imaging optimized for 1030nm excitation and a compromise-free option within the spectral gap between existing green and red GECIs.

RHODOPSIN 7: An ancient non-retinal photoreceptor for contrast vision, darkness detection, and circadian regulation
Rhodopsins are G protein-coupled receptors (GPCRs) specialized for light detection. In Drosophila, most rhodopsins are expressed in the retina and mediate image formation. However, RHODOPSIN 7 (RH7) exhibits a wider distribution, particularly in the optic lobe and in certain brain neurons, including a subset of dorsal clock neurons (DNs). In contrast to the classical rhodopsins, RH7 acts outside the retina and perceives ambient light for behavioral adaptation. We investigated its role using phylogenetic and sequence analyses, expression studies, and a series of behavioral assays. Our results show that RH7 detects simple light-on and light-off transitions and modulates circuits involved in contrast sensitivity, motion detection, and circadian synchronization, among others. The special role of RH7, independent of image formation, is supported by behavioral analyses of Rh70 mutants, Rh7-rescue experiments, and studies using the Darkfly strain. From an evolutionary perspective, RH7 potentially represents an intermediate stage between ancient GPCRs and specialized rhodopsins and provides insight into the early steps of photoreception evolution.

Sleep deprivation selectively reactivates hippocampal CA1 pyramidal neurons.
Sleep supports a variety of physiological processes, ranging from metabolic to immune system homeostasis, and plays a critical role in cognition and memory. A brief period of sleep loss impairs memory, particularly hippocampus-dependent memories, and alters molecular signaling and synaptic plasticity in the hippocampus. Studies have shown that sleep deprivation (SLD) alters neuronal activation as indicated by broad changes in gene expression signatures and by the altered expression of c-Fos, an immediate early gene (IEG) that functions as a molecular marker of neuronal activity. In the present study, we examined hippocampal subregion-specific c-Fos induction patterns. We find that CA1 pyramidal neurons exhibit the most robust c-Fos induction after SLD. Within CA1, the proximal region, where spatial information is processed and encoded, shows higher c-Fos levels after SLD as compared to the distal region. Using an activity-driven ribosomal tagging system and a repeated SLD model, we identify a specific population of excitatory neurons in area CA1 that are reactivated by repeated SLD. This approach also enables analysis of individual gene expression from c-Fos+ neurons to identify specific molecular signatures of neurons sensitive to repeated sleep loss. In summary, our study provides a detailed view of the activation of hippocampal neurons after SLD, revealing a subset of CA1 pyramidal neurons having higher sensitivity to the effect of sleep loss and laying the groundwork for further research investigating molecular changes in neurons specifically impacted by repeated sleep loss.

μ-Opioid Endomorphins and DDP-IV Inhibitor SitagliptinEnhance Amyloid-Beta Clearance and Memory in anAlzheimer's Cell Model
Alzheimer's Disease is a neurodegenerative disorder caused by A{beta}42 aggregation. Endomorphins 1 and 2 (EM1, EM2), two novel -opioid agonists, have been implicated in protecting against A{beta}42 toxicity, though it is unclear how the endomorphins achieve their effects. Phase one of the study found that EM1 and EM2 activation protected A{beta}42-treated cells. This protection, mediated by -opioid receptor (MOR) activation, also reduced rotenone-induced oxidative stress, both in a dose-dependent manner. Pretreatment with naloxone, a -opioid antagonist, reversed these effects, confirming MOR involvement in EM1 and EM2's actions. In phase two, molecular docking techniques suggested that sitagliptin can prevent intracellular EM1 degradation. In vitro assays demonstrated that sitagliptin enhanced intracellular EM1's beneficial effects in promoting cell survival and reducing cell apoptotic activity, A{beta}42 aggregation, and hydrogen peroxide free radical concentrations. This suggests intracellular EM1 can mitigate the toxic effects of A{beta}42 aggregation. However, sitagliptin did not enhance EM1's effects on BDNF expression or neurite outgrowth, suggesting that MOR activation, rather than intracellular EM1, primarily drives mechanisms associated with memory improvement. Collectively, our findings suggest that both intracellular EM1 and EM1-mediated MOR activation offer potential therapeutic avenues for mitigating memory impairment in Alzheimer's and potentially COVID-19. Furthermore, this research underscores the critical role of the MOR in broader memory mechanisms.

Aging and false memories: Comparing effects of item-relatedness and list position
Semantic false memories are traditionally more frequent from early list positions and thought to arise from presumed long-term memory stores whereas phonological false memories traditionally are more frequent from late list positions and thought to arise from presumed short-term memory stores. However, recent research with younger adults challenges this distinction, finding semantic and phonological false memories across stores and list positions (Atkins & Reuter-Lorenz, 2008; Dimsdale-Zucker et al., 2018; Flegal et al., 2010). Since aging is thought to differently influence integrity of short- and long-term memory, we compared performance between younger (YAs) and older (OAs) adults using a modified Deese-Roediger-McDermott paradigm to understand whether semantic and phonological memories depend on distinct or shared underlying memory stores. We examined false memory generation across age groups, list composition (semantic, phonological), and putative memory stores. OAs recalled fewer items than YAs, but both groups generated more phonological than semantic false memories. Notably, list position did not influence false memories in either YAs or OAs, suggesting false memory generation is driven by list composition rather than putative memory store. These findings challenge traditional views of memory organization by revealing shared cognitive processes, which transcend traditional memory system distinctions, underlie semantic and phonological false memories.

Altered Gut Microbiota Mediates the Association between APOE Genotype and Amyloid-β Accumulation in Middle-Aged Adults
Importance: The apolipoprotein E (APOE) {varepsilon}4 allele is the strongest genetic risk factor for Alzheimer's disease (AD), yet the mechanisms linking APOE to amyloid-{beta} (A{beta}) pathology remain incompletely understood. Emerging evidence suggests that the gut microbiome may modulate neurodegeneration; however, its role as a mediator in the APOE-A{beta} relationship remains unclear. Objective: To evaluate whether specific microbial taxa mediate APOE-related effects on brain A{beta} burden in an established population-based study of middle-aged adults. Design, Setting, and Participants: This cross-sectional study analyzed data from the Framingham Heart Study cohort. Data were collected at the third examination visit (n = 227, %Female = 58, mean age = 56.5 {+/-} 8.3), between 2016 and 2019. Exposures: Gut bacterial DNA was sequenced using 16S rRNA, and amplicon sequence variants (ASVs) were agglomerated at various taxonomic levels (14 phyla, 70 families, and ~140 genera). APOE genotypes were derived from blood DNA using PCR and restriction isotyping. Predicted microbial functional potential was based on KEGG Orthologs. Main Outcomes and Measures: Overall and regional measures of cerebral amyloid-{beta} deposition were assessed using carbon-11 Pittsburgh (PiB) Compound-B PET scans. The global PiB deposition served as the primary outcome for overall amyloid burden. Regional amyloid deposition values were analyzed as secondary outcomes. Results: A higher A{beta} burden was significantly associated with the depletion of protective genera (e.g., Faecalibacterium {beta} [95%CI], -0.35 [-0.40, -0.30]; Ruminococcus -0.25 [-0.27, -0.23]; Butyricicoccus -0.27 [-0.32, -0.22]) and the enrichment of pro-inflammatory taxa (e.g., Alistipes 0.07 [0.06, 0.08], Bacteroides 0.10 [0.07, 0.13]) and Barnesiella (0.18 [0.16, 0.20]). These associations were more pronounced in APOE {varepsilon}4 carriers, who exhibited a broader spectrum of microbial dysbiosis. Mediation analysis showed that Ruminococcus, Butyricicoccus, Clostridium, and Christensenellaceae collectively mediated ~0.3-0.4% of the effect of APOE {varepsilon}4 on global A{beta} burden. Functional profiling revealed a reduced abundance of microbial genes involved in key metabolic pathways among individuals with higher A{beta} levels. Conclusion and Relevance: Gut microbiome composition partially mediates the relationship between APOE {varepsilon}4 and cerebral amyloid burden. These findings support a gut-brain axis mechanism in AD and suggest that microbiome-targeted interventions may mitigate APOE-related risk.

Aging-enhanced accumulation of fibroblasts excludes oligodendrocytes in demyelinated lesions
Fibroblast dysregulation contributes to aberrant repair and pathological fibrosis. Emerging evidence suggest that fibroblasts accumulate in lesions following central nervous system injury, but whether and how they influence oligodendrocytes and myeloid cell responses, especially in aging, is uncertain. Here we report that fibroblasts infiltrate the parenchyma of spinal cord white matter (SCWM) lesions after lysolecithin-induced demyelination. Transcriptomic analysis reveals diverse activation states of fibroblasts in lesions and communication networks between fibroblasts, microglia/macrophages and oligodendrocyte precursor cells (OPCs). The invasion of fibroblasts is facilitated by microglia/macrophages, and areas of fibroblast accumulation are devoid of OPCs. Fibroblast density is exacerbated with aging leading to greater fibrosis in lesions. Finally, we found fibroblasts in multiple sclerosis lesions with predicted communication networks between microglia/macrophages and OPCs. These results demonstrate a role of fibroblasts in demyelination-associated neuropathology, which is exacerbated by aging, and highlight the importance of regulating fibroblasts to promote effective CNS repair.

Currentscape analysis of dendritic inputs during place field dynamics
Neuronal activity is driven by the complex interplay between various membrane currents, often located in distinct domains of the spatially extended dendritic tree. How the effect of these currents propagates to the soma and contributes to neuronal output under in vivo conditions is not fully understood. Here, we extend the currentscape method to measure and visualise the contributions of individual membrane currents to the somatic response in spatially extended biophysical model neurons. Our approach relies on the recursive decomposition of the axial current flowing between neighbouring compartments in proportion to the underlying membrane currents. We apply this method to visualise the inputs driving hippocampal place cell activity. Our method provides a compact and intuitive description of the various dendritic events underlying subthreshold activity, spiking, or burst firing. By contrasting the dendritic input currents preceding spiking and bursting, we demonstrate that both could occur at highly variable input levels to proximal dendrites (basal and oblique), and that strong distal inputs facilitates, rather than controls, the generation of complex spike bursts. Our method opens a novel window onto single-neuron computations that will help to design better models and to interpret the results of in vivo imaging experiments.

Psilocybin Prolongs the Neurovascular Coupling Response in Mouse Visual Cortex
Psilocybin has profound therapeutic potential for various mental health disorders, but its mechanisms of action are unknown. Functional MRI studies have reported the effects of psilocybin on brain activity and connectivity; however, these measurements rely on neurovascular coupling to infer neural activity changes and assume that blood flow responses to neural activity are not altered by psilocybin. Using two-photon excited fluorescence imaging in the visual cortex of awake mice to simultaneously measure neural activity and capillary blood flow dynamics, we found that psilocybin administration prolonged the increase in visual stimulus-evoked capillary blood flow - an effect which was reduced by pretreatment with a 5 HT2AR antagonist - despite not causing changes in the stimulus-evoked neural response. Multi modal widefield imaging also showed that psilocybin extends the stimulus-evoked vascular responses in surface vessels with no observed effect on the population neural response. Computational simulation with a whole-brain neural mass model showed that prolonged neurovascular coupling responses can lead to spurious increases in BOLD-based measures of functional connectivity. Together, these findings demonstrate that psilocybin broadens neurovascular responses in the brain and highlights the importance of accounting for these effects when interpreting human neuroimaging data of psychedelic drug action.

Machine Learning Resolves Functional Phenotypes and Therapeutic Responses in KCNQ2 Developmental Epileptic Encephalopathy iPSC Models
Pathogenic KCNQ2 variants are associated with developmental and epileptic encephalopathy (KCNQ2-DEE), a devastating disorder characterized by neonatal-onset seizures and impaired neurodevelopment with no effective treatments. KCNQ2 encodes the voltage-gated potassium channel KV7.2, which regulates action potential threshold and repolarization. However, the relationship between KV7.2 dysfunction and abnormal neuronal activity remains unclear. Here, we use human induced pluripotent stem (iPSC)-derived neurons from 5 KCNQ2-DEE patients with pathogenic variants and CRISPR/Cas9-corrected isogenic controls to investigate pathophysiological mechanisms. We identify a common dyshomeostatic enhancement of Ca2+-activated small conductance potassium (SK) channels, which drives larger post-burst afterhyperpolarizations in KCNQ2-DEE neurons. Using microelectrode arrays (MEAs), we recorded over 18 million extracellular spikes from >8,000 neurons during 5 weeks in culture and then applied supervised and unsupervised machine learning algorithms to dissect time-dependent functional neuronal phenotypes that defined both patient-specific and shared firing features among KCNQ2-DEE patients. Our analysis identified irregular spike timing and enhanced bursting as functional biomarkers of KCNQ2-DEE and demonstrated the significant influence of genetic background on phenotypic diversity. Importantly, using unbiased machine learning models, we showed that chronic treatment with the KV7 activator retigabine rescues the disease-associated functional phenotypes with variable efficacy. Our findings highlight SK channel upregulation as a critical pathophysiological mechanism underlying KCNQ2-DEE and provide a robust MEA-based machine learning platform useful for deciphering phenotypic diversity amongst patients, discovering functional disease biomarkers, and evaluating precision medicine interventions in personalized iPSC neuronal models.

The Role of Secretome from Mesenchymal Stromal Cells in Promoting Nerve Regeneration After Neurotmesis
Introduction: Neurotmesis, the most severe form of peripheral nerve injury, remains a significant clinical challenge due to limited intrinsic regenerative capacity and suboptimal outcomes of current therapies. Mesenchymal stromal cells (MSCs) secretome has emerged as a promising cell-free alternative, providing neurotrophic and immunomodulatory factors to support nerve repair while avoiding the limitations of cell transplantation. This study aimed to evaluate the regenerative efficacy of primed adipose-derived MSC secretome in a rat model of sciatic nerve neurotmesis. Materials and Methods: Human and rat adipose-derived MSCs were cultured and primed under hypoxic and inflammatory conditions. Secretomes were characterized by nanoparticle tracking analysis, proteomics, and total protein quantification. Neurotmesis was induced in Wistar rats, followed by repair with biomaterial alone or combined with human or rat secretome. Functional recovery was assessed by neurophysiological measurements (CMAP, NAP) at 6 months. Molecular and protein analyses included qPCR for myelination genes and ELISA for NGF. Morphological regeneration was evaluated by histology, immunofluorescence, and transmission electron microscopy (TEM). Results: Secretome priming enhanced the secretion of neurotrophic factors (GDNF, VEGFA, FGF2) and immunomodulatory proteins (IL6, CCL2), as confirmed by transcriptomic and proteomic analyses. In vivo, secretome-treated groups showed significantly improved neurophysiological recovery, with restoration of CMAP/NAP amplitudes and increased NGF levels. qPCR revealed upregulation of myelination-associated genes (MPZ, Krox-20, c-Jun) in treated nerves. Histological and TEM analyses demonstrated robust axonal regeneration, thicker myelin sheaths, and the presence of Remak bundles. Conclusions: Primed MSC secretome markedly enhances structural and functional recovery after sciatic nerve neurotmesis, supporting its potential as a safe, effective, and scalable cell-free therapy for peripheral nerve repair. These findings provide a strong rationale for further translational studies and clinical development.

Protein trafficking and synaptic demand configure complex and dynamic synaptome architectures of individual neurons
Excitatory synapses are the most abundant synapse type in the brain and are essential for behaviour and implicated in hundreds of brain disorders. These synapses exhibit striking structural and functional diversity, arising from differences in their proteomic composition and turnover. Synaptome mapping at single-synapse resolution reveals that this diversity is spatially organised along the dendritic tree of individual neurons. However, the cell biological mechanisms underlying the generation of these spatial synaptic patterns and their variation across neuron types and throughout the lifespan remain poorly understood. To investigate the contributions of somatic and dendritic protein synthesis, protein trafficking, and local regulatory mechanisms such as activity-dependent degradation, we developed computational models simulating these processes and compared their predictions with empirical synaptome data. We found that an extended sushi-belt model for spatial trafficking and local synaptic demand for proteins was sufficient to explain the complex profiles of synaptic protein distributions observed in young, mature and old mice and in different cell types. Our findings suggest the highly complex and dynamic synaptome architecture of the brain is an emergent property of a minimal set of cell biological processes. Our model sets the stage for simulations of brain tissue incorporating molecularly diverse neuronal and synaptic types in a synaptome and connectome architecture.

Neural Mass Model of Auditory Stimulus Responses in Marmoset Cortex.
A composite, heterogeneous neural mass model of the marmoset auditory and pre-frontal cortex (pFC) is used to model negativity mismatch experiments. This builds upon previous analysis of a compact pFC cluster. Simulated average deviant response delays were 136 ms for Auditory areas, and two groups: 174 and 139 ms for pFC areas, comparable to the 100-250 ms experimentally measured range. Details of responses for each anatomical area are presented. Area TPO is a key output node from the auditory cluster with strong links to pFC. Area AuA1 is activated by the deviant, high frequency, stimulus then turns off after the standard stimuli cease. Inactivation of AuRPB causes ambiguous spikes in AuA1 and reduced responses, consistent with experimental observations. the simulations facilitate analysis of the driving forces arriving at AuA1 and suggests that feedback from AuRPB to AuA1 is carried over multiple local network pathways. The simulations reproduce the experimentally observed delays and dissect the roles of participating areas and pathways.

The tri-culture system reveals an activation cascade from microglia through astrocytes to neurons during neuroinflammation
Neuroinflammation is involved in various neurodegenerative diseases, with glial cells playing crucial roles. It is known that neuroinflammation is initiated by microglia, which interact with astrocytes and neurons. However, the detailed molecular mechanisms underlying intercellular interactions during neuroinflammation are not fully understood. To elucidate these mechanisms, multicellular culture systems are required, although the availability of the culture systems using human cells is limited. In this study, we developed a tri-culture system of neurons, astrocytes, and microglia derived from human induced pluripotent stem cells (iPSCs) to evaluate their relationships in neuroinflammation. Previously, differentiation of astrocytes from iPSCs was commonly induced using serum. However, serum stimulation has been reported to cause irreversible activation of astrocytes. Therefore, we generated astrocytes using a serum-free method and established a tri-culture system. Microglia cocultured with the astrocytes and neurons exhibited a morphology with branched processes compared to the monoculture system, suggesting a homeostatic state. By applying lipopolysaccharide (LPS) stimulation to induce inflammation, the microglial morphology shifted to an amoeboid shape, accompanied by an increase in the expression of pro-inflammatory cytokines. Additionally, nuclear translocation of NF-{kappa}B revealed that LPS specifically activates microglia through the TLR4 receptor, which subsequently releases TNF-, leading to the activation of astrocytes. Furthermore, activated astrocytes were shown to enhance neuronal excitability. Using the tri-culture system, we elucidated a part of the cascade involving microglia, astrocytes, and neurons during neuroinflammation and demonstrated the amplification of inflammatory signals through cell communication. This culture system will be valuable for conducting detailed investigations into the interactions between glia and neurons, advancing research on neurodegenerative diseases associated with neuroinflammation.

Topographic alignment of auditory inputs to the visual cortex
Sensory cortical areas send long-range projections to cortical areas from other sensory modalities, supporting multisensory integration to generate a unified representation of the external world. However, the organizational principles underlying these extensive cross-modal connections remain poorly understood. In this study, we investigated the anatomical and functional organisation of auditory cortex inputs in the visual cortex. We found that populations of anatomically segregated auditory cortex neurons project to different visual cortical areas, broadcasting distinct auditory information to the dorsal and ventral visual processing streams. While sound frequency information was homogenously distributed across visual cortical areas, sound location information was differentially broadcast across the visual cortex. Specifically, sound azimuth and elevation were differentially encoded across visual cortical areas and streams matching the retinotopic bias of the target area. These findings suggest that cross-modal cortico-cortical connections follow a simple rule whereby specialised projection pathways are topographically aligned with the organisational principles of the target sensory area, ensuring spatially coherent integration of multisensory signals.

Chamber Implant for Chronic Optical Recordings from the Cerebral Cortex of Marmosets
We describe a novel imaging chamber for chronic optical recordings from the marmoset cerebral cortex, together with the surgery needed for its implantation and that of a headpost. MRI data allow optimizing positioning on the skull. The chamber is implanted into a precisely matched craniotomy, improving mechanical stability. For maximal biocompatibility, chamber and headpost are made out of titanium. It consists of an outer cylinder into which adjustably screws an inner one, called ''well'', with a glass window on its bottom. This allows easy opening and closing whenever access to the cortex is needed, while preserving a sterile seal when closed. Moreover, simply rotating the well allows fine adjustment of the window's distance with respect to the underlying cortex. Together with using a curved - rather than flat - glass window, this allows achieving gentle but continuous contact with the underlying cortex, which helps to delay tissue regrowth of, notably of a neomembrane that must otherwise be surgically removed. The chamber's sealing system combines a silicone elastomer and O-ring, minimizing infection risk and CSF leakage. Data from longitudinal two-photon imaging using genetically encoded fluorescent calcium sensors reveal high optical quality over months, with excellent resolution of neurons and their activity. We also demonstrate the feasibility of two-photon imaging of genetically encoded voltage sensors in the marmoset cortex in-vivo. Finally, although the chamber provides a durable, adaptable solution for long-term imaging studies in marmosets already in its current version, we discuss a few straightforward modifications that could likely improve its performance even further.

Dorsal Attention Network as a Convergent Hub of Diverse Non-pharmacological Interventions Preserving Functional Gradients and Cognition in Aging
Non-pharmacological interventions (NPIs) in aging neuroscience have largely focused on intervention-specific regional effects, with limited understanding of generalizable network-level mechanisms. Here, adopting a previously unexplored gradient-based perspective of functional brain organization, we analyzed an NPI dataset involving four interventions in older adults (training/control group: n = 112/59). NPIs led to strengthened intra-network functional integration and maintained macroscale gradient architecture. Virtual lesion analyses identified the dorsal attention network (DAN) as a key contributor to gradient maintenance. Critically, enhanced post-intervention DAN connectivity was associated with maintained gradient structure and improved global cognition. These findings establish a unifying framework in which the DAN acts as a convergent hub through which diverse NPIs preserve functional brain organization and attenuate cognitive aging.

EARLY TARGET PREDICTION IN ACTION OBSERVATION
Previous research has established that observers can predict action targets through hand preshaping. However, two critical questions remain unexplored: how predictions adapt to the available kinematic information and evolve throughout the movement timeline. We address these fundamental gaps by combining kinematic analysis with machine-learning approaches that differentiate between motor and visual cues. Using motion capture technology, we recorded reach-to-grasp actions toward large and small objects and had participants predict target size from hand kinematics at varying time points. Our analysis revealed that prediction performance not only evolved with increasing kinematic information but, crucially, differed significantly between target size choices. To provide insight into the underlying processes, we developed a comparative framework using two distinct machine learning approaches: Support Vector Machines (SVM) modeling kinematic information and CNN-RNN networks extracting visual patterns. The stronger alignment between human performance and SVM predictions offers empirical evidence that kinematic cues, rather than visual patterns, mostly guide target prediction. These findings advance our understanding of action prediction and have significant implications for social cognition and human-machine interaction.

Involuntary feedback responses reflect a representation of partner actions
We have a remarkable ability to seamlessly and rapidly coordinate actions with others, from double dutch to dancing. Humans use high-level partner representations to jointly control voluntary actions, while other work shows lower-level involuntary feedback responses to sudden visual perturbations. Yet, it is unknown if a high-level partner representation can be rapidly expressed through lower-level involuntary sensorimotor circuitry. Here we test the idea that a partner representation influences involuntary visuomotor feedback responses during a cooperative sensorimotor task. Using two experiments and dynamic game theory predictions, we show that involuntary visuomotor feedback responses reflect a partner representation and consideration of a partner's movement cost (i.e., accuracy and energy). Collectively, our results suggest there is top-down modulation from high-level partner representations to lower-level sensorimotor circuits, enabling fast and flexible feedback responses during jointly coordinated actions.

Effect of sleep stages on patterns of fNIRS hemodynamic response to auditory paradigms in one-month-old Gambian and UK infants
Significance: Functional near-infrared spectroscopy (fNIRS) has advanced our understanding of early brain development, especially infant responses to social and auditory stimuli. Unlike older children and adults, very young infants are often assessed during natural sleep to reduce movement and ensure sufficient data quality. Yet the impact of sleep stage on fNIRS signals and how it might affect interpretations of early brain activation patterns remains unclear. Aim: This study investigates the effect of sleep stages on fNIRS-measured hemodynamic responses to two auditory paradigms across different global populations of one-month-old infants. Approach: In total, 46 Gambian and 40 UK infants in quiet or active sleep were tested using (1) social selectivity and (2) a habituation and novelty detection paradigms. Results: In the UK cohort, active sleep was associated with a stronger initial response and greater habituation compared to quiet sleep. In contrast, Gambian infants in quiet sleep showed more widespread activation and evidence of habituation, while infants in active sleep showed no habituation. No sleep stage effects were observed for response in the social selectivity paradigm in either group. Conclusions: Different effects of sleep stages were observed across the two cohorts and paradigms and should be carefully considered in neuroimaging studies.

Modeling Withdrawal States in Opioid-Dependent Mice with Machine Learning
Understanding opioid withdrawal behaviors in preclinical models is critical to improving therapeutic approaches for opioid use disorder (OUD). However, quantifying these withdrawal behaviors remains a difficult process for researchers, given the subtlety of behaviors and variation across individuals. To overcome these difficulties, we developed a scalable behavioral analysis pipeline using LUPE (Light aUtomated Pain Evaluator), an open-source framework integrating video acquisition, pose estimation, supervised and unsupervised classification, and expert guided behavior discovery. Mice undergoing naloxone precipitated opioid withdrawal were recorded and analyzed using DeepLabCut for markerless pose estimation. We hand annotated withdrawal-specific behaviors, including jumping, genital licking, grooming, and paw tremors, and normal behaviors, including walking, rearing, and being still, using Behavioral Observation Research Interactive Software (BORIS) to generate frame-by-frame ethograms. The annotations and pose data were then imported into Active learning Segmentation of Open field in DeepLabCut (A SOiD), an active learning platform for behavior classification. A-SOiD successfully detected some behaviors (e.g., grooming and rearing) which were of a longer duration, though other rapid behaviors (e.g., jumping and paw tremors) were inconsistently captured. While no novel behavioral motifs have been discovered yet, ongoing work aims to refine model performance. This LUPE based pipeline sets the groundwork for standardized, high resolution behavior quantification and is being applied to additional datasets to investigate whether new components of the withdrawal phenotype emerge across experimental conditions.

Chemerin-CMKLR1 mediated OGD/R induced Mitochondrial Dysfunction, Oxidative Stress, and Autophagy differentially in Microglia and Neurons
Introduction: Ischemia-reperfusion (I/R) injury exacerbates tissue damage upon reperfusion after ischemia. The impact of chemerin and its receptor, chemokine-like receptor 1 (CMKLR1) on I/R injury remains poorly understood. We hypothesized that chemerin-CMKLR1 differentially regulates signaling in microglia and neuronal cells oxygen-glucose deprivation/reoxygenation (OGD/R), influencing mitochondrial function, oxidative stress, and autophagy. Methods: Using BV2 microglia and Neuro-2a (N2a) neuronal cells, we examined OGD/R-induced changes in autophagy associated proteins, chemerin and CMKLR1 expression. We investigated the functional consequences of CMKLR1 overexpression and chemerin treatment on oxidative stress, apoptosis, autophagy, and mitochondrial dynamics in BV2 microglia and N2a neuronal cells. Results: OGD/R downregulated CMKLR1 while upregulating autophagy in both BV2 microglia and N2a cells; While chemerin expression decreased in BV2 microglia but increased in N2a cells following OGD/R. Treatment with chemerin dose-dependently reduced oxidative stress and apoptosis while enhancing mitochondrial fusion, suppressing fission, and promoting autophagy and mitochondrial function in both cell types under OGD/R. CMKLR1 overexpression exacerbated mitochondrial respiratory dysfunction, mitochondrial fusion, fission, and elevated autophagy (LC3II/LC3I and Pink1 levels), with cell-type-specific differences observed in Parkin and P62 regulation. Conclusion: Our study demonstrates cell-type-specific regulation of chemerin-CMKLR1 signaling in I/R injury, and distinct mitophagy activation mechanisms in microglia and neurons. These findings suggest cell-type specific modulation of chemerin-CMKLR1 as a potential therapeutic target in preserving mitochondrial homeostasis, modulating autophagy, mitophagy and reducing oxidative stress, apoptosis in both microglia and neurons for mitigating I/R injury.

A Drosophila Tonic Motor Neuron Reinnervates Ectopic Muscles Fully Deprived of Native Tonic and Phasic Inputs
Motor neurons (MNs) form precise neuromuscular junctions (NMJs) during development, but the extent to which individual MNs can reinnervate fully denervated muscles in vivo remains poorly understood. In the Drosophila larva, each muscle is co-innervated by a tonic and a phasic glutamatergic MN. Here, we show that the tonic MN1 undergoes robust heterosynaptic sprouting and forms ectopic NMJs when neighboring muscles are deprived of both their native tonic and phasic inputs. This structural plasticity is not induced by silencing, but instead requires the physical ablation of adjacent MNs. Live imaging of the same MN1 axons in individual animals reveals that sprouting initiates early and expands progressively across larval stages. In contrast, phasic MNs show minimal remodeling, indicating that tonic MNs possess a greater intrinsic capacity for neuroplasticity. Notably, as MN1 establishes new synapses on targets it does not normally innervate, it redistributes pre-synaptic territory across both native and ectopic muscles. These findings identify a subtype-specific, injury-induced rewiring program in an intact motor circuit.

Examining Cross-Paradigm fNIRS Brain Activity in Neonates across The Gambia and UK
Significance: Neonates undergo rapid development, yet the examination of emerging brain markers across paradigms, cognitive domains and diverse global populations remains limited. Aim: This study investigated whether brain responses at one-month-of-age could be interrogated across paradigms to offer deeper context-specific insights into neurodevelopment. Approach: Functional near-infrared spectroscopy (fNIRS) was used to assess frontal and temporal brain responses during natural sleep in 181 Gambian (GM) and 58 UK infants during three auditory paradigms: Social Selectivity, Habituation and Novelty Detection (HaND) and Functional Connectivity (FC). Paradigm-level brain responses were analysed using threshold-free cluster enhancement and cross-paradigm comparisons of individual responses. Results: At the group level, both GM and UK infants showed habituation but not novelty responses, higher inter- versus intra-hemispheric connectivity, stronger inter-hemispheric connectivity in temporal regions relative to frontal regions, stronger inter-regional connectivity between right temporal and left frontal regions, and UK infants also showed non-vocal > vocal selectivity. Conclusions: Cross-cohort differences in the cross-paradigm analyses suggest context-specific developmental markers are evident within the first month of life and show high individual variability. Cross-paradigm analyses revealed that greater vocal selectivity (UK) was associated with higher inter-hemispheric connectivity, potentially allowing us to identify biomarkers of more mature neurodevelopment within the first weeks of postnatal life.

Foot Sole Cutaneous Somatosensory Modulation Based on Balance Demands
Postural complexity may shape how the nervous system processes plantar cutaneous input. We tested whether somatosensory evoked potentials (SEPs) elicited by foot sole stimulation scale with balance demands, hypothesizing larger responses for more complex tasks. Thirty one healthy adults performed standing, straight step, and diagonal step conditions while receiving brief electrical stimulation to the stance foot sole; SEPs (P50, N90, peak to peak) were analyzed at Cz using pooled and order specific approaches. In the pooled analysis, peak to peak SEP amplitude was greater for both stepping conditions than standing (Standing vs. Straight, P=0.041; Standing vs. Diagonal, P=0.026). Order specific analysis showed an early amplification: the first SEP (0.5s after the warning cue) was larger for diagonal than straight stepping (peak to peak, P=0.009; N90, P=0.027). Source localization at N90 revealed greater activation during stepping than standing in paracentral gyrus & sulcus, inferior parietal angular gyrus, and superior parietal gyrus, consistent with enhanced sensorimotor processing under higher postural demands. Moreover, right paracentral gyrus & sulcus activity was higher for diagonal vs. straight stepping for the first and fourth SEPs. Together, these findings indicate that increasing balance demands up weight plantar afferent processing and recruit contralateral sensorimotor/parietal regions, particularly early in preparation, supporting the view that cortical sensory gain is tuned to postural complexity.

Extracellular spike waveform analysis reveals cell type-specific changes in the superior colliculus of fragile X mice
A long-standing goal of neuroscience has been to elucidate the diverse complement of neurons in the brain, which can be defined by several criteria. Analysis of action potential shape in extracellular recordings has revealed subpopulations in several regions of the brain, allowing for insights into neuronal subtype-specific function in the intact brain. The superior colliculus (SC) is a critical sensorimotor region, integrating visual, somatosensory, auditory, and nociceptive inputs to direct complex behaviors. Recent work suggests that the SC may be adversely impacted in neurodevelopmental disorders (NDDs), underscoring its importance. However, our understanding of cellular diversity in the SC lags in comparison to other regions, limiting our ability to parse circuit changes in NDDs. Here, we utilized semi-automated clustering methods to classify neurons in the mouse SC based on multiple features of extracellularly recorded waveforms to identify five putative cell types. Secondary analysis of firing statistics and visual tuning properties supported the cluster segregation. Interestingly, the proportions of units assigned to each cluster differed in the SC of a mouse model of fragile X syndrome (FXS, Fmr1-/y), with only four of five types identified. Furthermore, we observed changes in waveform properties and firing statistics, but not visual tuning properties, between genotypes in a subtype-specific manner. Taken together, these data add to our understanding of neuronal diversity in the SC and alterations of visual circuit organization and function in NDDs.

Arm position estimates derived from motor biases
Proprioception, including position sense, is critically important for normal sensorimotor and perceptual functioning but remains poorly understood. In the laboratory and clinic, arm position sense is typically assessed using perceptual tasks, e.g., via arm position matching or reporting the arm's current position against a previously sensed one. Although such assessments provide important information about position sensing, they are incomplete in that they do not directly address the role of position sense in motor planning and control. Here, we used a combination of human psychophysical experiments, forward dynamic simulations, and mathematical optimization to reverse engineer arm positions ('REAP') used during motor planning. Subjects performed arm movements in a virtual environment under conditions where visual arm position cues were either aligned with corresponding somatosensory cues or were shifted prior to reach onset in one of four directions. Under shifted conditions, subjects exhibited characteristic 'motor biases', i.e., systematic deviations from ideal trajectories to the visually-cued targets. The arm positions used to plan movements under shifted conditions were obtained by minimizing differences between the experimentally induced motor biases and simulated motor biases. These REAP estimates largely conformed to predictions derived from previous perceptual experiments in that they were strongly influenced by the visual cues, and in a manner that was axially dependent. The results suggest that assessments of position sense derived from motor biases can be used to augment perceptual assessments or be used in lieu of them when perceptual reporting isn't possible. In addition, the observed similarities between position estimates and weights derived from motor and perceptual tasks suggest that the brain's perceptual and action systems use similar mechanisms to deduce arm position from somatosensory and visual cues.

Is the cortical dynamics ergodic? A numerical study in partially symmetric networks of spiking neurons
Cortical activity in-vivo displays relaxational time scales much longer than the membrane time constant of the neurons or the deactivation time of ionotropic synaptic conductances. The mechanisms responsible for such slow dynamics are not understood. Here, we show that slow dynamics naturally and robustly emerges in dynamically-balanced networks of spiking neurons. This requires only partial symmetry in the synaptic connectivity, a feature of local cortical networks observed in experiments. The symmetry generates an effective, excitatory self-coupling of the neurons that leads to long-lived fluctuations in the network activity, without destroying the dynamical balance. When the excitatory self-coupling is suitably strong, the same mechanism leads to multiple equilibrium states of the network dynamics. Our results reveal a novel dynamical regime of the collective activity in spiking networks, where the memory of the initial state persists for very long times and ergodicity is broken.

CD33-CD45 Interaction Reveals a Mechanistic Link to Alzheimer's Disease Susceptibility
The innate immune gene CD33, encoding a myeloid inhibitory sialic acid-binding receptor, is associated with Alzheimer's disease (AD) susceptibility. The AD-associated rs3865444CC risk variant reduces splicing of the sialic acid-binding domain and increases expression of the full-length (sialic acid-binding) CD33 isoform seven-fold compared to the rs3865444AA protective genotype. Here, we identify CD45 as an immune cell-specific sialic acid-dependent cis CD33 binding partner, whose phosphatase activity is inhibited by CD33. Overexpression of CD33 or loss of CD45 contributes to impaired microglial clearance of amyloid beta and amyloid beta-induced loss of dendritic spines in microglial-neuronal co-cultures, aligning with a detrimental effect of CD33-mediated inhibition of CD45. CD33-CD45 interaction frequency was increased in monocytes from individuals with the rs3865444CC risk variant compared to rs3865444AA, as well as in AD compared to controls, independent of genotype. Furthermore, an interaction between CD33 and PTPRC (encoding CD45) gene expression in human brain tissue was associated with a pathological diagnosis of AD and global burden of AD pathology. Our findings thus establish a functional interaction between CD33 and CD45 relevant to AD susceptibility and systemic myeloid dysfunction in disease.

CD33 and Clusterin Interact Biophysically and Genetically to Modulate Alzheimer Risk
We report the results of structural, functional and genetic studies on the CD33 sialic acid-binding receptor that reveal how non-coding variants in CD33 alter risk for Alzheimer's disease (AD). The full-length CD33M isoform, whose expression is upregulated by non-coding AD-risk alleles, preferentially forms dimers at the cell surface, where they interact with AD-related proteins (clusterin and amyloid beta). This interaction induces CD33M inhibitory signalling and downregulates protective microglial functions including phagocytic removal of amyloid plaques. Human brain expression quantitative trait loci (eQTL) and causal mediation analyses confirm that quantitative interactions between CLU and CD33 genotypes modulate AD phenotypes and suggest that genotypes at these loci might be used to personalise future therapeutic approaches. Our work also highlights several other unexpected aspects of CD33 biology, including a soluble shed extracellular fragment of CD33M and a similar soluble secreted product arising from a truncating mutation in the CD33 extracellular domain.

Intracranial Insights into the Developing Neural Basis of Moral Punishment
Third-party punishment (TPP) is a critical component of social regulation and justice, integrating moral reasoning and emotional salience. However, the neural developmental basis underpinning this complex process remains largely unknown. Using rare intracranial stereoelectroencephalography (SEEG) in 14 children and 17 adults, we investigated the developing neural circuits of TPP. We found that broadband gamma activity in the amygdala and ventromedial prefrontal cortex (vmPFC) encodes inferred intentions, with different patterns across age groups. Furthermore, the vmPFC, insula, and inferior parietal lobule (IPL) integrate punishment efficacy, also showing significant developmental differences. Combining task and resting state functional connectivity analyses, we further found age-dependent interactions among the amygdala-insula and IPL-vmPFC neural couplings during decision-making. These findings provide valuable intracranial evidence that the maturation of moral decisionmaking stems from the developmental refinement of subcortical-cortical circuits that integrate emotional and cognitive evaluations, explaining the shift from intuitive decisions in children to context-sensitive judgments in adults.

Neural correlates of emotional responses to self-selected music: evidence from multivariate pattern analysis
Music is a uniquely powerful stimulus for evoking complex and deeply felt emotions. While previous research has identified neural correlates of music-evoked emotional responses, less is known about how these felt emotions are represented in the brain, particularly when elicited by familiar, personally meaningful music. Here, we used a personalized fMRI paradigm in which participants (N = 20) each selected musical excerpts corresponding to the nine emotion categories defined by the Geneva Emotional Music Scale. These self-selected excerpts were presented during functional MRI scanning. We first examined the neural correlates of music-evoked emotion by comparing brain activity during music listening to that during exposure to white noise. The maps were consistent with previous research, highlighting clusters in sensory and limbic regions. We then used multivoxel pattern analysis to decode emotion categories from whole-brain activation patterns. The results revealed that music-evoked emotions could be reliably discriminated based on distributed neural activity, with consistent involvement of the superior temporal gyrus, supplementary motor area, amygdala, and cerebellum, among other auditory, motor, and interoceptive regions. These findings provide new insight into the neural encoding of musical emotions and highlight the value of personalized, music-based paradigms for research in auditory and affective neuroscience.

The respiratory phase causally modulates the readiness potential amplitude
Previous research has shown that the respiratory phase correlates with both voluntary action timing and readiness potential (RP) amplitude, but whether this relationship is causal or merely correlational remains unclear. Here, we experimentally manipulated breathing patterns to test if the respiratory phase causally influences the neural preparation for voluntary movement. Participants performed self-initiated button presses under four conditions: breathing in (BI), breathing out (BO), normal breathing (NB), and breath-holding (BH). Electroencephalographic recordings revealed that RP amplitude was significantly more negative during exhalation compared to inhalation and during breath-holding compared to normal breathing. These neural differences occurred without corresponding changes in behavioral measures (e.g., waiting times or retrospective timing judgments), indicating that respiratory effects on RP were not associated with altered action timing. These findings demonstrate that the respiratory phase causally modulates cortical motor preparation. We further propose that the brain optimizes voluntary action execution during respiratory phases when breathing-related motor activity is minimal, thereby revealing respiration as a fundamental organizing rhythm for voluntary behavior.

Spatial specificity of the functional gradient echo and spin echo BOLD signal across cortical depth at 7 T
Functional magnetic resonance imaging (fMRI) at high magnetic field strengths ([≥] 7 T) is a promising technique to study the functioning of the human brain at the spatial scale of cortical columns and layers. However, measurements most often rely on the blood oxygenation level dependent (BOLD) response sampled with a gradient echo (GE) sequence, which is known to be most sensitive to macrovascular contributions that limit their effective spatial resolution. Alternatively, a spin echo (SE) sequence can be used to increase the weighting toward the microvasculature and, therefore, the location of neural activation. In addition, due to the heterogeneous structure of the cortical cerebrovascular system, the effective spatial resolution can change across cortical depth. For high-resolution fMRI applications, it is hence important to know how much the effective spatial resolution varies across cortical depth. In this study, we used flickering rotating wedge stimuli to induce traveling waves with varying spatial frequencies in the retinotopically organized primary visual cortex (V1), which allowed us to infer the modulation transfer function (MTF) of the BOLD response that characterizes the spatial specificity of the measured signal. We acquired GE- and SE-BOLD data at 7 T and compared the MTF between acquisition techniques at different cortical depths. Our results show a small but consistent increase in spatial specificity when using SE-BOLD. But across cortical depth, both acquisition techniques generally show a similar decrease of specificity toward the pial surface demonstrating the dependence on macrovascular contributions, which needs to be carefully considered when interpreting the results of high-resolution fMRI studies.

Tau conveys intrinsic hyperactivity of VTA dopamine neurons but an inability to sustain burst firing
INTRODUCTION: Ventral tegmental area (VTA) dopamine has been implicated in neuropsychiatric symptoms observed in Alzheimer's disease (AD) patients. Dopaminergic dysfunction and aberrant firing are observed in mouse AD models, but the specific roles of A{beta}; and tau have not been determined. METHODS: We performed electrophysiological recordings of single VTA dopamine neuron firing in the 3xTg-AD model, followed by recordings in amyloid (APPNL-G-F)- and human tau (hTau)-based models to determine the pathological triggers of impaired firing. RESULTS: In vivo dopamine neuron recordings showed fewer spikes in defined bursts in 3xTg-AD mice versus controls. Ex vivo studies showed an impaired ability to sustain firing during depolarization, which was mimicked with depolarized current in wild type neurons. Dopamine neurons transduced with hTau reflected firing aberrations and impaired bursting, but the effects were not recapitulated in the APPNL-G-F model, DISCUSSION: These results suggest that hTau specifically induces hyperexcitable states within individual dopamine neurons, disrupting burst firing. This dopaminergic dysfunction could compromise reward learning and contribute to the psychiatric symptoms observed in AD.

Structural Eigenmodes of the Brain to Improve the Source Localisation of EEG: Application to Epileptiform Activity
A fundamental view of neuroscience is that, in addition to neuronal activity, the structure of the brain constrains and explains brain function. An alluring formalism in computational neuroscience has been the generation of structural eigenmodes of neural activity from a matrix representing the anatomy of the brain. Traditionally, brain connectomics has been the gold standard for the coupling between structure and function. However, it has recently been suggested that simpler brain geometry can provide more explanatory power in fMRI. An adjacent modality is the source localisation problem of EEG, which aims to identify the underlying generators of EEG recordings. The underdetermined nature of the problem requires sufficient constraints to produce realistic and unique solutions of source activity. In this work, we presented a simple framework for incorporating different forms of structural brain eigenmodes to constrain the source localisation problem in epilepsy. We found that geometric eigenmodes were able to reconstruct the spread of a seizure through the brain slightly better than connectome eigenmodes, and both types of structural modes significantly outperformed commonly used approaches.

Dynamic updating of spatial working memory across eye movements: a computational investigation of transsaccadic integration
The brain continuously integrates rapidly changing visual input across eye movements to maintain stable perception, yet the precise mechanisms underpinning dynamic working memory and how these break down in brain diseases remain unclear. We developed a novel eye-tracking paradigm and computational models to investigate how spatial and colour information are updated across saccades. Our findings reveal that saccades selectively impair spatial but not colour memory. Computational modelling identified that spatial representations are maintained in a dual eye-centred frame of reference which is actively updated by a noisy memory of saccades but is vulnerable to interference. Using this model, we found that specific mechanistic failures in initial encoding and memory decay, rather than the saccadic updating process itself, account for spatial working memory deficits in Alzheimer's and Parkinson's disease. These results provide a mechanistic understanding of how dynamic spatial memory operates in health and its disruption in neurodegenerative disorders.

Structural Effects of Low Social Status and Obesogenic Diet on Social and Emotional Neurocircuits in Female Macaques: A Longitudinal Study from Infancy to Adulthood
A substantial body of literature has demonstrated a consistent link between psychosocial stress and obesity in children, particularly in those from low socioeconomic backgrounds. Despite evidence indicating a complex interplay between stress, diet and obesity, there is a limited understanding of the specific versus potentially synergistic effects of obesity and stress on brain structural and functional development. This study investigates the developmental and long-term brain structural alterations resulting from exposure to chronic social stress due to low (subordinate -SUB-) social status and postnatal obesogenic diets. Forty-one female rhesus macaques (Dominants -DOM-, n=21; Subordinates -SUB-, n=20) were assigned to either only low-calorie diet (LCD) or to both high-calorie diet (HCD) and LCD (Choice diet) from birth through the juvenile period. After menarche, all subjects were maintained on a LCD-only diet through adulthood. Twenty-seven animals (DOM: n=13, SUB: n=14) were studied again in adulthood to investigate the long-term effects of early diet and social rank on brain structure. Cumulative Kcal consumption was measured from birth through 16 months and body weights were measured at all time points. Overall, the findings show specific effects of obesogenic diet and psychosocial stress on cortical and corticolimbic brain regions. Animals with access to the obesogenic diet had larger overall brain size (measured as intracranial volume -ICV-) and larger overall volumes of prefrontal cortex, insula, superior temporal sulcus (defined as temporo-parieto-occipital area rostral and caudal regions (TPOr and TPOc)) than those in the low-calorie diet. Most of these regional diet effects, except for the insula, were driven by general effects of the diet on brain size. The diet effects were lost when adding the adult data to the longitudinal analysis, suggesting transient effects of obesogenic diets while the animals were consuming it, but not long-term, persistent effects. These findings highlight the potential of brain rescue mechanisms that could offset lasting developmental effects of early-life obesogenic diet consumption. With respect to social rank, SUB exhibited larger volumes in brain regions related to social cognition and emotional processing than DOM animals. When the adult data was added to the longitudinal analysis, the effects of social rank were prominent in the hippocampus, superior temporal sulcus, temporo-parieto-occipital rostral region, and the temporal auditory cortices after ICV data correction, suggesting long-term, persistent and cumulative effects of these social experiences, in contrast to the transient diet effects.

A multimodal approach for visualization and identification of electrophysiological cell types in vivo
Neurons of different types perform diverse computations and coordinate their activity during sensation, perception, and action. While electrophysiological recordings can measure the activity of many neurons simultaneously, identifying cell types during these experiments remains difficult. To identify cell types, we developed PhysMAP, a framework that weighs multiple electrophysiological modalities simultaneously to obtain interpretable multimodal representations. We apply PhysMAP to seven datasets and demonstrate that these multimodal representations are better aligned with known transcriptomically-defined cell types than any single modality alone. We then show that such alignment allows PhysMAP to better identify putative cell types in the absence of ground truth. We also demonstrate how annotated datasets can be used to infer multiple cell types simultaneously in unannotated datasets and show that the properties of inferred types are consistent with the known properties of these cell types. Finally, we provide a first-of-its-kind demonstration of how PhysMAP can help understand how multiple cell types interact to drive circuit dynamics. Collectively, these results demonstrate that multimodal representations from PhysMAP enable the study of multiple cell types simultaneously, thus providing insight into neural circuit dynamics.

Preparatory Cortical Modulations for Stepping Tasks with Varying Postural Complexity
We examined whether preparatory cortical activity indexed by the contingent negative variation (CNV) scales with postural complexity during step initiation. Participants performed straight and diagonal stepping in a Warning-Go paradigm while EEG was recorded; CNV epochs spanned the 2s fore period and were summarized into eight 0.25 s bins for electrode and eLORETA source level analyses using linear mixed effects models (n=31). Diagonal stepping produced greater early CNV negativity at the scalp (bin 1: C1, CP3, CP1, P1, FC4; bin 2: F1, F3, FC1, Fz, F2, F4, FC2, FCz), with no electrodes favouring straight stepping. Source analysis showed stronger engagement for diagonal stepping in bins 1-3 (0-0.75 s) across fronto parietal sensorimotor regions, including paracentral, transverse frontopolar, superior frontal (gyrus/sulcus), supramarginal, superior parietal, intraparietal, and precentral sulcus; no regions were greater for straight stepping. These effects concentrated in the early CNV suggest enhanced anticipatory selective attention and sensory up weighting under higher postural demands, providing a richer state estimate for scaling anticipatory postural adjustments.

Maternal Thyroid Supplementation Prevents Autistic-relevant Social Behavior and Hypothalamic Oxytocin Depletion Produced by Developmental Exposure to Environmental Toxicants
Environmental toxicants that target the developing brain are suspected of contributing to autism spectrum disorder risk but causative evidence is lacking. We and others have shown that the indoor flame retardants, polybrominated diphenyl ethers (PBDEs), reduce prosocial behavior, however, few studies have assessed the central targets and underlying mechanisms. PBDEs are well established endocrine disruptors of the expanded thyroid system, which also regulates the prosocial neuropeptides oxytocin (OXT) and vasopressin (AVP) and their hypothalamic signaling. The potential role of PBDE-induced thyroid hormone (TH) deregulation in mediating disruption of central OXT and ASD-like social behavior deficits remains unmapped. To address this gap, we conducted a study in C57BL6/N mice that examined behavioral and neuromolecular reprogramming after developmental exposure to the commercial PBDE mixture, DE-71, and evaluated the therapeutic potential of TH supplementation. Dams were exposed daily during gestation and lactation to corn oil vehicle, low dose (0.1 mg/kg) and high dose (0.4 mg/kg) of DE-71 with or without concurrent L-thyroxine (+mT4). In offspring, dose-dependent ASD-relevant behavioral responses and central neuroendocrine OXT neuron depletion after developmental PBDE exposure was prevented with mT4. mRNA transcripts for the TH transporter Mct8, deiodinase (Dio3) and estrogen receptor beta (Esr2) expressed on OXT neurons in PVH were upregulated in low dose females. In contrast, Mct8 and Dio3 were downregulated in low dose males. These findings uncover sex-specific mechanisms of PBDE-induced reprogramming of TH-regulated pathways in hypothalamic neuroendocrine cells leading to depleted central OXT signaling and ultimately ASD-relevant phenotypes. Importantly, we provide novel evidence of the therapeutic potential of maternal thyroid supplementation against toxicant-induced neurodevelopmental disorders.

Integration of sensory and cortical information in the brainstem during mastication in mice
Mastication is a vital function that relies on precise synchronization among multiple brainstem regions, known as being part of a central pattern generator (CPG). Movements can be triggered either by stimulating a sensory-motor region called the cortical masticatory area (CMA), well-documented in various species but not yet formally identified in mice, or by stimulating the oro-facial sensory primary afferents which fibers form the trigeminal tract (Vtr). However, it's unclear whether these different inputs activate distinct components of the CPG or converge on the same. This study aims at mapping brainstem areas activated by cortical and sensory inputs using immunohistochemistry against the cellular activity marker, c-Fos and Ca2+-imaging, respectively. Optogenetic stimulation of the cortical masticatory area (CMA) in awake, head-fixed mice reliably induced rhythmic jaw movements (RJMs) and increased c-Fos expression in multiple brainstem regions, with strongest activation in the peritrigeminal area (PeriV) and parvocellular reticular formation (PCRt) ventral to the trigeminal motor nucleus (NVmt). In contrast, in vitro electrical stimulation of trigeminal sensory afferents (Vtr) predominantly activated neurons and astrocytes in the main sensory nucleus (NVsnpr), the dorsal area of PeriV, adjacent to it, and PCRt. The areas containing the highest numbers of activated cells differed clearly according to the type of inputs and overlapped only in the PCRt, ventral and slightly medial to the trigeminal motor nucleus and the most dorso-medial part of PeriV. These findings demonstrate that cortical and sensory inputs take part in distinct components of the brainstem masticatory circuitry, with PCRt emerging as a point of convergence and provide new insights into the components of the CPG of mastication.

In Vivo Network-Level Cerebrovascular Mapping Reveals the Impact of Flow Topology on Capillary Stalls After Stroke
Cerebral microvasculature is essential for brain function, but how flow and large-scale connectivity contribute to its resilience or failure remains poorly understood. To address this, we developed OMNIMap, a framework for mesoscale in vivo mapping of functional microvascular networks, capturing flow dynamics and connectivity across thousands of capillaries. OMNIMap integrates extended-focus optical coherence microscopy and learning-based segmentation with global vessel-graph optimization to resolve artery-vein classification and branching order, linking capillary flow and stalls to broader network context. Applied to over 40,000 capillaries in the mouse cortex before and after ischemic stroke, we observe heterogeneous vulnerability patterns: while most capillaries stall or reduce flow after arterial occlusion, some experience accelerated flow. Further analysis revealed that stall-prone flow topology subtypes were less prevalent than their robust counterparts. Notably, the overall distribution of these subtypes remains largely preserved after stroke, revealing a previously unrecognized, system-level organizing principle that alleviates the impact of individual capillary stalls to maintain network-level perfusion.

Resolving the Brain Energy Paradox: The Neuron as a Coupled Thermodynamic System
Traditional models of neural excitability, such as the Hodgkin-Huxley framework, treat the action potential as a purely electrical phenomenon. While its thermodynamic footprint -including heat and entropy generation- is experimentally known, it is typically regarded as a passive consequence of signal propagation. This work explores the hypothesis that this thermodynamic output is not passive, but instead plays an active role in modulating neural function. To investigate this, we developed a novel, fully coupled electro-thermo-entropic model where the entropy generated by an action potential directly feeds back to influence the kinetics of ion channels. Our simulations demonstrate a profound consequence of this coupling: the action potential undergoes progressive self-amplification, driven by a massive acceleration of its underlying kinetics. As the signal propagates, its peak amplitude grows significantly while its temporal duration remains remarkably stable. Furthermore, a statistical analysis reveals that this mechanism relies on the system operating as a robust thermodynamic switch, transitioning between a low-entropy quiescent state and a high-dissipation active state. Finally, we show that achieving this high-performance, amplifying state requires a disproportionately high energetic cost, a finding we term the Intelligence Premium. These results suggest that the action potential is a coupled electro-thermodynamic process that actively enhances its own strength and reliability. Our model offers a candidate mechanism for how waste energy is repurposed into a functional signal, providing a physical explanation for the brain's high energy consumption and opening new perspectives on the link between thermodynamics and computation.

Targeting Tmem63b and Piezo2 in C-fiber low threshold mechanoreceptor: limitation of Vglut3-IRES-Cre
Peripheral somatosensory neurons in the dorsal root ganglia (DRG) transduce mechanical force in the skin and other organs into electrical signals using specialized mechanically activated (MA) ion channels that initiate neuronal activation in response to force. Increasing evidence highlights PIEZO2 as the primary transducer of low-threshold mechanical force in DRG neurons. However, in the absence of Piezo2, mice and humans still respond to noxious painful stimuli like pinch, suggesting that additional MA channel(s) likely exist in DRG neurons. Strategies to identify Cre lines and DRG subpopulations that select for non-PIEZO2 expressing neurons is therefore an ongoing effort in the field to discover unknown mechanosensors. Here, we investigated a Vglut3 labeled mouse line as a candidate to identify non-PIEZO2 MA channels in a subtype of DRG neurons called C-fiber low threshold mechanoreceptors (C-LTMRs). Our study carefully demonstrates that the Vglut3-IRES-Cre mouse line specifically and efficiently labels C-LTMR neurons of the DRG. Electrophysiological recordings using two different in vitro mechanical stimulation assays show that the genetically labelled Vglut3 neurons have robust indentation- and stretch-activated MA currents that are exclusively slowly or ultra-slowly adapting. To determine whether the Vglut3-IRES-Cre mouse line can be used to delete genes of interest and identify the underlying MA ion channels in C-LTMRs we attempted to generate a Tmem63b conditional knockout using this Cre-line but detected incomplete loss of Tmem63b transcript and lack of TMEM63B-dependent effect on C-LTMR MA currents. Together, our results emphasize that although the Vglut3-IRES-Cre line is robust in driving expression of a conditional reporter gene, it is inefficient in deleting genes like Tmem63b as well as Piezo2.

Representation Transfer via Invariant Input-driven Neural Manifolds for Brain-inspired Computations
Domain adaptation is a core challenge for embodied AI deployed in unpredictable, noisy environments. Conventional deep models degrade under domain shifts and require costly retraining. Inspired by biological brains, we propose a modular framework where each module is a recurrent neural network pretrained via a simple, task-agnostic protocol to learn robust, transferable features. This shapes stable yet flexible representations as invariant input-driven continuous attractor manifolds embedded in high-dimensional latent space, supporting robust transfer and resilience to noise. At deployment, only a lightweight adapter needs training, enabling rapid few-shot adaptation. Evaluated on the DVS Gesture benchmark and a custom RGB rehabilitation dataset, our framework matches or surpasses leading C3D and ViViT models while using ten times fewer parameters and only one training epoch. By unifying biologically inspired attractor dynamics with cortical-like modular composition, our approach offers a practical path toward robust, continual adaptation for real-world embodied AI.

in vivo Reprogramming of NG2 Glia Improves Bladder Function After Spinal Cord Injury
Neurogenic bladder is a debilitating consequence of spinal cord injury (SCI), with few treatment options that restore voluntary voiding. Here, we show that SOX2-mediated in vivo reprogramming of NG2 glia improves bladder function in a clinically relevant mouse model of contusive SCI. NG2 glia reprogramming induces adult neurogenesis, reduces glial scarring, and significantly improves urinary performance, as measured by voiding assays and conscious cystometry. Functional recovery correlates positively with neurogenesis and negatively with glial scarring. These findings demonstrate that SOX2-mediated glial reprogramming promotes autonomic repair and offers a regenerative strategy for neurogenic bladder after SCI.

Comparative transcriptomics of lateral hypothalamic cell types reveals conserved growth hormone-tachykinin dynamics in feeding
The lateral hypothalamus (LH) is a highly heterogeneous brain region regulating hunger and motivated behaviors. In zebrafish, the LH shows distinct neural activity across hunger, feeding, and satiety states. However, the functional and evolutionary conservation of relevant neural circuits remain unclear. Using integrative transcriptomics of zebrafish and mouse LH, we identify conserved cellular clusters with shared molecular markers, particularly within GABAergic neurons. We highlight a conserved GABAergic population expressing tachykinin and growth hormone receptors, which is responsive to food cues and modulated by hunger and feeding states. This cluster may mediate acute appetite-enhancing effects of growth hormone. In both species, feeding elevates growth hormone receptor and tachykinin expression and activates these neurons, while human growth hormone increases their activity and food intake in zebrafish. These findings suggest a conserved neural mechanism by which metabolic hormones influence feeding behavior. Our comparative LH atlas highlights the evolutionary biology of appetite regulation and the integration of hormonal and neural signals driving energy homeostasis.