bioRxiv Subject Collection: Neuroscience's Journal

Ptf1a robustly drives the gliogenic switch in the rodent embryonic cortex in a dosage-dependent manner by activating pro-glial gene expression programs
It is widely believed that the gliogenic switch during rodent embryonic development is governed by the orchestrated crosstalk between a cohort of genes and extracellular cues. Here we report that ectopic expression of the single bHLH factor, pancreas transcription factor 1 (PTF1A), is sufficient to drive radial glial progenitors (RGPs)-regardless of progenitor heterogeneity and developmental stage-to differentiate into glial cells. Ptf1a-expressing RGPs exhibit progenitor behaviors indicative of a neurogenic-to-gliogenic fate transition, resembling endogenous progenitors at the late stages of embryonic development, and preferentially produce OLIG2+ oligodendrocytes in vivo, some of which are positive for PDGFR or CC1. This robust gliogenic competency depends on the dosage of stable Ptf1a expression in RGPs. RNAseq reveals 'the glial transcriptome', including upregulated expression of several notch signaling components and the endothelin receptors in Ptf1a RGPs. We further identify Ednrb as one of the downstream targets of Ptf1a that directs RGPs toward gliogenesis via the ERK1/2 signaling pathway. In summary, our study uncovers a novel and robust role for Ptf1a in glial fate specification, offering a potential strategy for generating human oligodendrocytes in vitro.

Parallel circadian-like oscillations in LTP and excitation inhibition balance in mouse CA1 reverse direction after puberty
Long-term potentiation (LTP), the best characterized form of Hebbian synaptic plasticity, is well known to be under strong circadian regulation. In mice and rats, both nocturnal species, most studies indicate that LTP in the hippocampal CA1 region is more robust when induced during the dark phase. Our examination of the underlying mechanisms at the CA3 to CA1 synapse provides evidence that the capacity to express LTP does not differ between the light and dark cycles of the 24hour day. Instead, the magnitude of theta-burst stimulation induced LTP (TBSLTP) correlates with daily fluctuations in the ratio of synaptic excitation to inhibition (E/I ratio): both the E/I ratio and TBSLTP are higher during the dark phase. Consistent with a causal relationship, blockade of inhibition abolishes the light dark difference in TBS LTP induction, likewise, pairing induced LTP, which is less constrained by inhibitory recruitment, does not differ between cycles. Supporting this model, using the APP/PS1 model of AD we observed that neither the E/I ratio nor TBSLTP change during the light cycle. Finally, we made the intriguing observation that these daily oscillations reverse direction after puberty in WT mice, shifting from being larger in the dark cycle of 2month old mice to being larger in the light cycle in 8month old mice. This developmental switch may reflect an age-dependent reorganization of circadian control over hippocampal plasticity.

Electrical synapses mediate visual approach behavior
Detecting salient visual objects and orienting toward them are commonplace tasks for animals, yet the underlying neural circuit mechanisms remain poorly understood. The fruit fly is an ideal model for a comprehensive analysis of feature detection mechanisms given its complete synaptic wiring diagrams, robust behavioral assays, and cell-type-specific gene expression datasets. We previously showed that columnar visual neurons T3 are required for saccadic orientation toward landscape features during flight. Here, we examine how signals downstream of T3 are processed in the central brain. We identify the LC17 type of visual projection neurons as key postsynaptic targets: they receive strong excitatory input from T3, project to premotor brain regions, and are thus positioned to support visual approach. Using in vivo optical physiology and virtual reality behavior, we demonstrate that LC17 neurons are indeed necessary for object tracking during flight. Furthermore, we find that electrical synapses in LC17 are also required for tracking behavior. Accordingly, we show that the innexin Shaking B (shakB) is highly expressed in LC17 dendrites, and genetic perturbations confirm an essential role for gap junctional coupling in this circuit. Our findings reveal mechanisms underlying visual approach, and highlight the interplay between electrical and chemical neurotransmission for rapid object detection and action selection.

Region-specific human brain organoids reveal synaptic and cell state drivers of glioblastoma invasion
Glioblastoma (GBM) is a highly heterogenous and malignant brain tumor, in part because it disrupts normal brain circuits to fuel its own growth and invasion. Thus, there is a need to identify the molecular features of invasive GBM cells and their regulators in the neural microenvironment. To address this in a fully human model, we engrafted patient-derived GBM cells (total n=15 independent samples) from three sources - fresh neurosurgical resections, cell lines, and whole GBM organoids - into human induced pluripotent stem cell-derived organoids patterned to forebrain, midbrain, and spinal cord identities. GBM cells from all sources infiltrated brain organoids within 2 days post-engraftment, reaching maximal invasion by day 14. Across organoids of distinct spatial and maturational milieu, GBM cells showed a consistent reduction in astrocyte-like states and an enrichment in neuron/glia progenitor-like (NPC-like) states. These NPC-like GBM cells expressed neuronal and synaptic machinery, and tumors enriched in this transcriptomic state prior to engraftment achieved greater organoid coverage, suggesting enhanced infiltration and synaptic integration of this GBM cell type. Although GBM cell states converged across organoid types after engraftment, infiltration was greater in the forebrain than spinal cord. This is likely reflective of synaptic input from deep-layer TBR1 excitatory neurons in the forebrain, as demonstrated by a combination of rabies-based monosynaptic tracing and single-cell transcriptomics. In contrast, inhibitory neurons were the predominant synaptic partners of GBM in the spinal cord. Together, this fully human model of the neural-GBM connectome reveals how neuron-like GBM states and regionally distinct synaptic inputs cooperatively shape tumor invasion.

Functional and Structural Plasticity in Cocaine-Seeking Ensembles of the Nucleus Accumbens Core
Relapse vulnerability in substance use disorder (SUD) is primarily driven by cue-induced activation of neurons within the nucleus accumbens core (NAcore), among other contributing factors. Neuronal ensembles within the NAcore, defined here as selectively co-activated neurons during specific behavioral experiences, are essential during cocaine sensitization and recall. While transient synaptic plasticity (t-SP) has been widely observed in general neuronal populations within the NAcore during reinstatement, its ensemble-specific dynamics remain unclear. Here, we used c-Fos-TRAP2-based tagging to identify cocaine-seeking ensembles in mice following cocaine intravenous self-administration, extinction, and cue-induced reinstatement. Structural spine plasticity was assessed via confocal microscopy, and functional changes were measured using whole-cell electrophysiology across multiple reinstatement time points. Ensemble neurons exhibited enhanced dendritic spine head diameter (dh) and AMPA/NMDA (A/N) ratios following cue exposure, consistent with t-SP. Notably, spine classification revealed a reduction in mature spines during reinstatement, suggesting morphological remodeling rather than new spine formation in both ensemble and non-ensemble cells. Non-ensemble neurons exhibited classical functional transient synaptic plasticity, characterized by increased A/N ratios but no significant changes in dh. To begin assessing if presynaptic vesicle release impacts t-SP, paired-pulse ratio analysis indicated no differences in population or time point. Importantly, ensemble neurons displayed elevated A/N ratio following cocaine exposure, suggesting prior silent synapse maturation. These findings demonstrate that t-SP is not uniformly distributed across NAcore neurons but differs significantly between ensemble and non-ensemble neurons. By linking ensemble identity to both structural and functional plasticity, this study refines our understanding of cue-induced relapse mechanisms.

Iron Deficiency Impairs Mitochondrial Energetics and Early Axonal Growth and Branching in Developing Hippocampal Neurons
Each stage of neuronal development (i.e., proliferation, differentiation, migration, neurite outgrowth and synapse formation) requires functional and highly coordinated metabolic activity to ultimately ensure proper sculpting of complex neural networks. Energy deficits underlie many neurodevelopmental, neuropsychiatric and neurodegenerative diseases implicating mitochondria as a potential therapeutic target. Iron is necessary for neuronal energy output through its direct role in mitochondrial oxidative phosphorylation. Iron deficiency (ID) reduces mitochondrial respiratory and energy capacity in developing hippocampal neurons, causing permanently simplified dendritic arbors and impaired learning and memory. However, the effect of ID on early axonogenesis has not been explored. We used an embryonic mixed-sex primary mouse hippocampal neuron culture model of developmental ID to evaluate mitochondrial respiration and dynamics and effects on axonal morphology. At 7 days in vitro (DIV), ID impaired mitochondrial oxidative phosphorylation capacity and stunted growth of both the primary axon and branches, without affecting branch number. Mitochondrial motility was not altered by ID, suggesting that mitochondrial energy production --- not trafficking --- underlie the axon morphological deficits. These findings provide the first link between iron-dependent neuronal energy production and early axon structural development and emphasize the importance of maintaining sufficient iron during gestation to prevent the negative consequences of ID on brain health across the lifespan.

Persistence of vestibular function in the absence of glutamatergic transmission from hair cells
Quantal synaptic transmission in vestibular end-organs is glutamatergic. Although genetic deletion of Slc17a8 (termed Vglut3) leads to deafness in mice, the dependence of vestibular function on VGLUT3-mediated quantal transmission is unknown. Here, we investigated the vestibular phenotype of Vglut3-/- mice at the cellular, systems, and behavioral levels. The type-II vestibular hair cells (VHCs) in Vglut3+/+ mice were strongly immunoreactive for VGLUT3, while type-I VHCs showed poor immunoreactivity. In Vglut3-/- mice quantal synaptic transmission in utricular calyces was reduced in rate and amplitude by > 95%. In vivo recordings of spontaneous activity in the vestibular nerve revealed similar action potential rates and regularity in Vglut3+/+ and Vglut3 /- mice, suggesting a divergent underlying mechanism compared to the silent Vglut3-/- auditory nerve. In behavioral studies, Vglut3-/- mice did not exhibit considerable sensorimotor or balance deficits. Collectively, these data support the view that non-quantal transmission is the predominant mode of neurotransmission between type I VHCs and vestibular calyceal afferent neurons. We propose that non-quantal transmission alone underlies the apparently normal vestibular nerve physiology and behavioral function in Vglut3-/- mice.

Decoding with multivariate pattern analysis is superior for optically pumped magnetometer-based magnetoencephalography compared to superconducting quantum interference device-based systems
Background: Multivariate pattern analysis (MVPA) has become an increasingly important method for decoding distributed brain activity from neural electrophysiological recordings by leveraging both temporal and spatial features. These multivariate approaches have proven important for both cognitive neuroscience and brain-computer interfaces. MVPA might benefit from magnetoencephalography (MEG) systems based on optically pumped magnetometers (OPMs), as these sensors can be placed closer to the scalp, providing higher spatial resolution compared to conventional MEG systems that rely on superconducting quantum interference devices (SQUIDs). As OPM-based MEG systems become available at more institutions, it is essential to experimentally compare their performance with traditional SQUID-based systems using MVPA. Methods: We adapted a visual object-word paradigm from a previous study, originally implemented on a TRIUX MEGIN SQUID system, to the FieldLine HEDscan OPM system. Participants were recruited and we recorded their ingoing brain activity while did the same task in both systems. Visual stimuli of different objects were presented alternately in two modalities: pictures and the corresponding written words. For each modality, MVPA was used to classify the objects from OPM and SQUID magnetometers data respectively. To further investigate the advantages of OPM, we evaluated the effect classification accuracy of two spatial factors by controlling the number of sensors included and the spatial frequency content of the sensor data. Results: We found higher time-resolved decoding accuracy for the OPM compared to the SQUID data. Moreover, OPMs show higher classification performance compared to SQUIDs when controlling for the same number of sensors; consistently, the OPM system required fewer sensors to reach the performance limit of the SQUID system. Our analysis considering the spatial frequency content of the signal revealed that decoding accuracy plateaued for the SQUID system at lower spatial frequencies while the performance of the OPM system continued to improve when higher-order spatial components were included. Conclusion: Our OPM-MEG system outperformed the SQUID-MEG system on MVPA on decoding of visual processing. This advantage of OPM is driven by its higher spatial resolution, resulting from the sensors being positioned closer to the head and thus able to capture higher spatial frequency components of the brain signal. OPM may facilitate cognitive neuroscience research as well as brain-computer interfaces by providing higher sensitivity when employing paradigms using multi-variate data analysis.

Early reduction and impaired targeting of myelin-associated glycoprotein to myelin membranes in Huntington disease
Background. Huntington disease (HD) is a hereditary life-threatening disease marked by progressive neuronal loss and atrophy of grey matter structures, particularly the caudate putamen. Brain imaging studies have revealed that the degradation of the white matter occurs many years prior to symptomatic onset and neuronal loss, suggesting that the decay of brain white matter is an active contributor to the disease progression. However, the mechanisms by which the HD mutation triggers white matter loss is not well understood. Methods. Western blot, immunohistochemistry, and electron microscopy were conducted to assess white matter pathology and explore the relevant mechanisms in CAG140 knock-in mice, which express the HD protein in the same way as patients suffering from HD and thus biologically replicate HD in human. Results. Western blot analysis of proteins localized at different layers of the myelin coat revealed that the myelin-associated glycoprotein (MAG), which is localized at the innermost layer of the myelin coat and essential for maintaining the periaxonal space and the integrity of the myelin sheath, manifested as an early and progressive decline in HD mouse caudate putamen. The loss of MAG was detected at myelinated axons and in fiber bundles in HD mouse brains at an age when the abundance of myelinated axons was normal. Fluorescence immunohistochemical studies found that MAG labeling was concentrated in the soma of a subset of oligodendrocytes, which expressed breast carcinoma amplified sequence 1, a marker for new oligodendrocytes. While their abundance was normal, new oligodendrocytes in HD mouse caudate appeared to be impeded in acquiring the expression of MAG and in targeting MAG away from perinuclear punctate structures to processes, signs of impaired maturation. Compared with those in wildtype mouse brains, oligodendrocytes in HD mouse brains had a reduced abundance of small vesicles whereas an increased abundance of large punctate structures in the perinuclear region, implying defective generation of small vesicles transporting MAG from large punctate structures in the soma to processes. The MAG-containing perinuclear punctate structures were negative for proteins specifying trans-Golgi networks, early endosomes, or exosomes but had a minor portion labeled with lysosome-associated membrane protein 1, indicating that the structures where MAG accumulates in the soma are derived from the late endosomal lysosomal compartment. Conclusions. Our study suggests that the decay of the brain white matter in Huntington disease involves a deficit in trafficking of myelin-associated glycoprotein, preventing its proper delivery from the soma of oligodendrocytes to myelin-forming processes.

Oxidation of ΔFOSB at Cys172 Controls Hippocampal Gene Targets and Learning
Imbalance of reduction/oxidation (redox) in the brain is associated with numerous diseases including Alzheimers disease (AD), substance abuse disorders, and stroke. Moreover, cognitive decline can be caused by neuronal dysfunction that precedes cell death, and this dysfunction is in part produced by altered gene expression. However, the mechanisms by which redox state controls gene expression in neurons are not well understood. DeltaFOSB is a neuronally enriched transcription factor critical for orchestrating gene expression underlying memory, mood, and motivated behaviors. It is dysregulated in many conditions including AD. We showed recently that deltaFOSB forms a redox-sensitive disulfide bond between cysteine 172 (C172) of deltaFOSB and C279 of its preferred binding partner JUND. This bond works as a redox switch to control DNA-binding, based on studies of recombinant proteins in vitro. Here, we show that this redox control of deltaFOSB function in vitro is conserved in vivo. We show that deltaFOSB C172 forms a redox-sensitive disulfide bond with JUND that regulates the stability of this AP1-transcription factor complex and its binding to DNA in cells. We also validate the formation of deltaFOSB-containing complexes held together via disulfide bonds in mouse brain in vivo. We show that exogenous oxidative stress reduces deltaFOSB binding to gene targets in mouse brain and that Fosb C172S knock-in mice, which lack a functional deltaFOSB redox switch, are insensitive to this oxidation-dependent reduction in target gene binding, demonstrating that deltaFOSB is regulated by a redox switch that modulates binding to target genes in the hippocampus. Finally, we demonstrate that FosB C172S knock-in mice are less sensitive to cognitive dysfunction induced by oxidative stress. This evidence supports deltaFOSB as an important mediator of oxidative stress-driven changes in gene expression and cognition and implicates deltaFOSB as a possible therapeutic target for diseases associated with oxidative stress in the brain, including AD.

Uncertainty Shapes Neural Dynamics in Motor Cortex During Reaching
Voluntary reaching movements are often made with incomplete information about the movement goal, which may require the brain to flexibly adjust motor plans and ongoing movements. To examine how uncertainty about a reach target influences neural preparation and execution, we recorded activity from dorsal premotor (PMd) and primary motor (M1) cortices of a rhesus macaque trained to reach to one of two potential targets. In the task, a timing cue flashed three times in succession. Potential targets were displayed at the time of the first flash and the monkey needed to initiate the movement almost simultaneously with the third flash. Colorings of potential targets indicated the probability that the target would be at one location or the other, thereby inducing varying levels of uncertainty about the final target location. On half the trials, the final target was displayed so late that the monkey had to "guess" the target location, based on cues provided by the potential targets. While the monkey performed this task, we recorded 165 neurons from PMd and 37 from M1. Population neural trajectories in the preparatory subspace of PMd (but not M1) were progressively less expansive with higher levels of uncertainty. Despite differences in preparatory states associated with uncertainty, the movements produced were the same. The narrower separation between states suggested a neural-based explanation for more rapid movement re-preparation with higher uncertainty. Furthermore, we found a dimension in neural state-space representing the level of uncertainty during movement preparation and execution.

Chronic Dietary Exposure to Methylparaben and Ethyl paraben Induces Developmental, Biochemical, and Behavioural Toxicity in Drosophila melanogaster
Abstract Parabens, particularly methylparaben (MP) and ethylparaben (EP), are extensively used preservatives in cosmetics, foods, and pharmaceuticals. Although considered safe at low concentrations, recent evidence questions their biological inertness under chronic exposure. This study evaluated the developmental, biochemical, and behavioural effects of continuous dietary MP and EP exposure in Drosophila melanogaster, an established in vivo model for toxicological screening. Flies were chronically exposed to MP (0.5 to 2%) or EP (0.5 to 1.5%) throughout development and adulthood. Developmental timing, lifespan, oxidative-stress markers (MDA, FRAP, total protein), and locomotor performance (negative geotaxis in adults, crawling in larvae) were quantified. Paraben exposure significantly delayed development (a 15% increase in eclosion time), reduced median lifespan (up to a 50% decrease at 2% MP), and increased oxidative damage (MDA and FRAP) in a dose-dependent manner. Protein content declined more rapidly with age, suggesting oxidative degradation or proteolysis. Both adult climbing and larval crawling performances were impaired, indicating a link between biochemical stress and neuromuscular dysfunction. MP produced stronger oxidative and behavioural effects than EP. Feeding controls confirmed that observed deficits were not due to nutritional differences. Chronic MP and EP exposure induces systemic toxicity in D. melanogaster, integrating endocrine disruption and redox imbalance as plausible mechanisms of action. Given conserved stress and hormonal pathways, these findings reinforce the need to re-evaluate low dose paraben safety limits and highlight Drosophila as a rapid, ethically viable platform for screening environmental preservatives and safer substitutes.

Detection of probable neuronal gene expression changes in skin biopsies from patients with paclitaxel-induced peripheral neuropathy
Our inability to obtain nerve samples from the vast majority of neuropathic pain patients impedes our ability to understand the disease, creates challenges in understanding mechanisms in specific patient populations, and limits our ability to make treatment decisions based on quantifiable molecular data. Fields like oncology have overcome these problems to take advantage of the insight that sequencing offers for understanding mechanisms of disease and have leveraged these molecular insights to dramatically change the treatment landscape in the past decade. Here we tested the hypothesis that skin biopsies could be used to gain insight into neuronal transcriptomic changes in patients with paclitaxel-induced peripheral neuropathy (PIPN). Our analysis reveals that hundreds of differentially expressed genes (DEGs) found through bulk RNA sequencing in these skin biopsies are likely contributed by dorsal root ganglion (DRG) neuronal axons and/or terminals. Up-regulated genes were representative of broad class of nociceptors whereas down-regulated genes were associated with putative injured DRG neurons expressing the PDIA2 gene. DEGs that could be confidently associated with specific subsets of skin cells were mostly expressed by keratinocytes supporting a growing literature tying keratinocyte-neuron communication abnormalities to pain in PIPN. Our findings warrant further assessment of skin biopsies in additional neuropathic pain populations to gain insight into DRG neuron changes that have previously been thought to be inaccessible in routine clinical or scientific assessment in most patients.

Biomimetic Cues Enable Predictive Mechanisms in Simulatedand Physical Robot-Human Object Handovers
Object handovers - while representing one of the simplest forms of physical interaction between two agents - involve a complex interplay of predictive and reactive control mechanisms in both agents. As human-human pairs have unrivaled skills in physical collaboration tasks, we take the approach of understanding and applying biomimetic concepts to human-robot interaction. Here, we apply the concept of passer movement cues, that is, slower movement for heavy objects and faster movements for lighter objects, to robot-human handovers. We first show that when a simulated passing agent's movement is scaled with object mass, participants as receivers adapt their anticipatory grip forces according to mass in a virtual environment. We then apply the same concept to a physical robot-human handover and show that our approach generalizes to the real-world. The predictive scaling of grip forces is learned iteratively upon repeated presentations of trajectory-mass pairings, whether the masses are presented in a random or blocked order. Overall we demonstrate that the presentation of robotic kinematic cues can provide intuitive and naturalistic human predictive control in object handover. This extends the use of non-verbal cues in robot-human handover tasks and facilitates more legible and efficient physical robot-human interactions.

Microglial morphology reflects cognitive status in the aging rat brain
Age-related cognitive decline affects millions of individuals worldwide, but the cellular mechanisms underlying this decline remain incompletely understood. Microglia undergo significant changes with aging, including alterations in morphology, that may reflect or contribute to cognitive dysfunction. However, the relationship between specific microglial morphologies and cognitive performance in relevant brain regions remains poorly understood. To address this, we evaluated the relationship between morphology-based microglial phenotypes and cognitive performance across domains affected by aging. Microglial morphology was analyzed in four cognitive brain regions of male and female 3-, 9-, and 15-month-old rats and features were subjected to hierarchical clustering on principal components to identify microglial subtypes. Rats underwent cognitive testing using a radial arm water maze and a T-maze set-shifting task to assess spatial working and reference memory, striatal-based learning, and cognitive flexibility. We observed age-related cognitive impairments alongside region-specific changes in microglial morphotype abundance. Importantly, the relative abundance of distinct microglial clusters correlated with cognitive performance in functionally relevant brain regions including the prefrontal cortex, the orbitofrontal cortex, and the hippocampus. Taken together, these findings highlight the utility of morphological profiling in capturing microglial heterogeneity and suggest that morphological changes may reflect or contribute to cognitive decline during aging.

Mismatch negativity develops in adolescence and independently of microglia
Higher brain functions and cognition undergo a critical period of development during adolescence, when psychiatric disorders such as schizophrenia typically onset. Understanding how developmental processes during adolescence interact with schizophrenia pathophysiology and risk remains a central goal in psychiatry. Here we show that a well-established biomarker of schizophrenia, mismatch negativity, matures during adolescence in mouse primary visual cortex, along with a strengthening of fronto-visual functional connectivity. Because microglia are implicated in schizophrenia risk and disease states, we further investigated what role microglia may play in the development of mismatch responses under physiological conditions. We found that microglial depletion with PLX5622 in adolescence arrests the development of resting oscillations in frontal areas, but does not affect the development of deviance detection, other signatures of visual context processing, or prefrontal-visual functional connectivity. Our findings suggest (a) a key component of mismatch negativity develops in adolescence, a period of vulnerability to schizophrenia, and (b) the development underlying this component does not require robust microglia activity, clarifying the developmental role of microglia in higher order visual processing.

Gene therapy-mediated overexpression of wild-type MFN2 improves Charcot-Marie-Tooth disease type 2A
Charcot-Marie-Tooth disease type 2A (CMT2A) is the most common axonal CMT and is associated with an early onset and severe motor-dominant phenotype. CMT2A is mainly caused by dominant mutations in the MFN2 gene, encoding Mitofusin-2, a GTPase located in the outer membrane of the mitochondria and endoplasmic reticulum (ER). Mutations in MFN2 are known to affect mitochondrial dynamics. We previously demonstrated that the mutated MFN2Arg94Gln further disrupts contacts between the ER and the mitochondria, leading to progressive axonal degeneration. There is no effective therapeutic approach to slow or reverse the progression of CMT2A, and treatments currently under development primarily focus on restoring mitochondrial function. Here, we provide proof-of-concept that neuronal overexpression of wild-type MFN2 (MFN2WT) provides therapeutic benefit in transgenic CMT2A mice carrying the mutated MFN2Arg94Gln. Intrathecal delivery of an AAV9 vector expressing MFN2WT effectively targets motor and sensory neurons, restoring ER-mitochondria contacts and mitochondrial morphology, thereby preserving both neuromuscular junction integrity and motor function. Strikingly, therapeutic efficacy is also achieved following vector injection after the onset of symptoms, rescuing the molecular hallmarks of CMT2A pathology and reversing locomotor. Notably, AAV administration was well tolerated, with no evidence neither of hepatotoxicity nor dorsal root ganglion inflammation. These results establish that boosting MFN2 levels using gene therapy is a promising therapeutic avenue for CMT2A

Representational Competition of Spatially and Temporally Overlapped Target and Distractor
Representational competition occurs when a task-relevant target stimulus and a distractor overlap in space and time. Given limited neural resources, it is expected that stronger representations of the distractor will result in weaker representations of the target, leading to poorer behavioral performance. We tested this hypothesis by recording fMRI while participants (n = 27) viewed a compound stimulus consisting of randomly moving dots (the target) superimposed on IAPS affective pictures (the distractor). Each trial lasted ~12 seconds, during which the moving dots and the IAPS pictures were flickered at 4.29 Hz and 6 Hz, respectively. The task was to detect and report brief episodes of coherent motion in the moving dots. Depending on the emotion category of the IAPS pictures, the trials were classified as pleasant, neutral and unpleasant. Focusing on three ROIs: middle temporal cortex (MT), ventral visual cortex (VVC), as well as the primary visual cortex (V1), we performed MVPA analysis to decode the distractor categories in each ROI, and correlated the decoding accuracy, taken to index the strength of distractor representation, with the accuracy in detecting the episodes of coherent motion. The following results were found: (1) the decoding accuracy was above chance level in all ROIs, and (2) in MT and VVC but not in V1, the higher the decoding accuracy, the worse the behavioral performance. These results suggested that distractor information was represented in V1 as well as in the two motion-processing areas, and in the motion-processing areas, stronger representations of the distractor led to poorer ability to process attended information, leading to worse behavioral performance. The hypothesis was thus supported and trade-offs in the fidelity of stimulus representations prompted by neural competition demonstrated.

Knockdown of endothelial Serpine1 improves stroke recovery by attenuating peri-infarct blood flow and blood brain barrier disruption
Focal stroke leads to complex changes in the cerebral microcirculation in surviving brain tissues that strongly influence recovery. Plasminogen activator inhibitor-1 (PAI-1; encoded by Serpine1) is highly upregulated in endothelial cells after stroke. Since the primary function of PAI-1 is to inhibit fibrin clot breakdown, we hypothesized that blocking this pathway would be beneficial for recovery since it is expected to increase capillary blood flow after stroke. Using longitudinal in vivo imaging in mice subjected to ischemic stroke, we unexpectedly found that knockdown of Serpine1 in brain endothelial cells leads to a long-lasting reduction in peri-infarct capillary width, red blood cell velocity and flux. Conversely, stimulating this pathway in naive mice increased capillary width and blood flow. Lowered peri-infarct blood flow in Serpine1 knockdown mice attenuated deleterious blood brain barrier disruption and pro-inflammatory gene expression. Serpine1 knockdown improved the progressive recovery of sensory evoked cortical responses, as well as cognitive and sensorimotor function. These findings challenge the assumption that increased blood flow after stroke is better for recovery and reveal that carefully tuning flow, rather than maximizing it, may be optimal. Further our data highlight the therapeutic potential of targeting endothelial Serpine1/PAI-1 signalling in promoting stroke recovery.

Using Information Geometry to Characterize Higher-Order Interactions in EEG
In neuroscience, methods from information geometry (IG) have been successfully applied in the modelling of binary vectors from spike train data, using the orthogonal decomposition of the Kullback-Leibler divergence and mutual information to isolate different orders of interaction between neurons. While spike train data is well-approximated with a binary model, here we apply these IG methods to data from electroencephalography (EEG), a continuous signal requiring appropriate discretization strategies. We developed and compared three different binarization methods and used them to identify third-order interactions in an experiment involving imagined motor movements. The statistical significance of these interactions was assessed using phase-randomized surrogate data that eliminated higher-order dependencies while preserving the spectral characteristics of the original signals. We validated our approach by implementing known second- and third-order dependencies in a forward model and quantified information attenuation at different steps of the analysis. This revealed that the greatest loss in information occurred when going from the idealized binary case to enforcing these dependencies using oscillatory signals. When applied to the real EEG dataset, our analysis detected statistically significant third-order interactions during the task condition despite the relatively sparse data (45 trials per condition). This work demonstrates that IG methods can successfully extract genuine higher-order dependencies from continuous neural recordings when paired with appropriate binarization schemes.

Spatial and semantic memory reorganize a hippocampal long-axis gradient
The hippocampus supports episodic memory by binding spatial and semantic information, yet how this information is simultaneously organized along its long axis remains debated. Gradient accounts propose a continuous shift in representational scale, from coarse coding in anterior to fine coding in posterior regions, whereas modular accounts posit discrete subregions specialized for distinct functions. Using high-resolution fMRI together with eye tracking as a readout of spatial and semantic memory during sequence learning, we directly tested these competing models. During predictable sequences, hippocampal activity continuously varied along the long axis. In contrast, modular organization emerged when sequences mismatched memory. Subregions in the anterior and posterior hippocampus were sensitive to semantic and spatial mismatches, respectively. Notably, the intermediate hippocampus was specifically sensitive to concurrent mismatches in both dimensions, but not to mismatches in either dimension alone. These content-sensitive subregions were embedded within distinct cortical networks that reorganized according to memory demands. Together, our findings show the hippocampus flexibly combines gradient and modular dynamics to simultaneously represent the spatial and semantic content that defines episodic memory.

Developmental sleep reallocation enables metabolic adaptation in desert flies
Sleep is essential for adaptation and survival across the lifespan, yet the ecological pressures shaping sleep ontogeny remain poorly understood. We investigated sleep across early developmental stages in Drosophila mojavensis, a stress-resilient desert-adapted species. While adult D.mojavensis exhibit prolonged and consolidated sleep, along with enhanced starvation tolerance and survival compared to Drosophila melanogaster, the developmental trajectory underlying these adaptation strategies for surviving in harsh environments is unknown. Moreover, during developmental (larval) periods, animals do not encounter the same environmental stressors experienced by adults (e.g., food scarcity, extreme temperatures). We find that in contrast to adults, D.mojavensis larvae exhibit reduced and fragmented sleep relative to D.melanogaster. D.mojavensis larval sleep is also deeper, reflecting a shift toward increased sleep efficiency rather than simple sleep loss. D.mojavensis larvae consume more food than D.melanogaster and survive longer under starvation, suggesting a strategic tradeoff by suppressing sleep to prioritize nutrient intake and energy storage early in life while resources are more abundant. Metabolic analyses reveal elevated triglyceride accumulation in D.mojavensis across their lifespan, indicating enhanced energy storage capacity. These findings provide an example of how, within a fixed genetic background, an animal can reallocate sleep in opposing manners to maximize survival and energetics depending upon ecological pressures unique to each phase of life.

An EEG Investigation of Neural Dynamics of Empathy Influenced by Congruent and Incongruent Pain Expressions in Autistic and Neurotypical Adults
Autistic individuals often show difficulties in empathy, but the underlying neural mechanisms of empathy in naturalistic contexts of pain have been less examined. This study employed a kinetic pain empathy paradigm, manipulating the congruence between pain expressions, i.e., body gestures and facial expressions based on a predictive coding framework. We collected EEG data from 51 autistic and 58 neurotypical adults during a pain observation task. Results indicated that autistic and neurotypical adults share a similar neural architecture for empathy processing and conflict resolution, involving an early stage of sensory arousal (i.e., N2 and theta) and a later stage of cognitive reappraisal (i.e., P3). However, the multivariate pattern analysis (MVPA) revealed nuanced but significant between-group differences in neural patterns. Compared to neurotypical peers, autistic adults demonstrated atypical processes in both empathy and conflict resolution. Specifically, they exhibited heightened early emotional arousal but expended greater cognitive effort to evaluate others' pain. Autistic adults also showed increased alertness to unexpected sensory input and allocated more cognitive resources to resolve prediction errors from incongruent pairings. In contrast, neurotypical adults suppressed unnecessary cognitive efforts for meaningless errors. In summary, autistic adults may experience challenges in efficiently adjusting predictions to the external context, with their neural processing heavily depending on sensory input and less efficient in adapting cognitive resources to evaluate and respond to varied contextual demands.

Hippocampal grey matter changes across scales in Alzheimer's Disease
Alzheimer's disease (AD) is a progressive and debilitating neurodegenerative disease of the central nervous system, characterized by deterioration in cognitive function including extensive memory impairment. The hippocampus, a medial temporal lobe region, is a key orchestrator in the encoding and retrieval of memory and is believed to be one of the first regions to deteriorate in AD. In this work we examined hippocampal macrostructure (specifically gyrification and thickness) and microstructure in AD and mild cognitive impairment (MCI) relative to healthy aged controls in the Alzheimer's Disease Neuroimaging Initiative (ADNI) dataset. We first utilized an iterative training paradigm to adapt an existing deep learning approach for capturing hippocampal topology to elderly individuals as well as individuals with potential hippocampal degeneration. Using this new model, we found notable decreases in both thickness and gyrification in AD and MCI across both the subfields and anterior-posterior axis. Using the diffusion tensor representation derived from diffusion MRI data, we found significant increases in the mean diffusivity across the extent of the hippocampus in AD and MCI, which may be related to a number of changes such as loss of neuronal cells, decreased fiber density, demyelination, and increased presence of CSF. Examining the primary direction of diffusion relative to canonical hippocampal axes, we found distinct diffusion orientation shifts in AD and MCI throughout the anterior-posterior extent of the subiculum and CA1. Specifically, we found a decrease in diffusion oriented tangentially, and an increase in diffusion oriented along the long-axis. This could potentially be related to the known degeneration of the perforant path, which is greatly affected in AD and is a largely tangential oriented pathway. The AD-related changes in diffusion orientations were found to not have significant spatial overlap with AD-related changes in mean diffusivity, suggesting that they may be capturing distinct spatially-localized disease processes. Finally, we showed that the macro- and microstructure of the hippocampus in AD changed less across age relative to MCI and controls. As well, the age-related hippocampal macrostructure changes in MCI appeared indistinguishable from healthy aging.

The difference in immunohistochemical reactivity of monoclonal antibodies against amino-terminal residues of amyloid-β peptide
Immunohistochemistry for amyloid-{beta} (A{beta}) peptide is an indispensable method for Alzheimers disease (AD) research. Despite a wide variety of available antibodies against the peptides, the difference of immunohistochemical reactivity is not fully described among anti-A{beta} antibodies. Immunohistochemical reactivity of Abs against A{beta} peptides is critical for accurate and reliable evaluation of A{beta} burden in patients as well as models of AD. Here, we examined immunohistochemical reactivity of two mouse and one rabbit monoclonal antibodies against A{beta} N-terminal regions using two AD mouse models, AppNL-F and AppNL-G-F. 6E10, 82E1 and D54D2 A{beta} antibodies were used in this study. We found significant differences in the immunohistochemical reactivity in both AppNL-F and AppNL-G-F models. While 6E10 immunoreactivity was mainly localized to A{beta} plaques, D54D2 and 82E1 antibodies stained much more broadly beyond plaques. Interestingly, the latter two Abs showed blurred filamentous immunoreactivity beyond amyloid plaque cores. Double immunostaining using a tyramide signal amplification method, Fluorochromized Tyramide-Glucose Oxidase (FT-GO), suggested that the differential immunohistochemical outcomes were only partially attributable to their sensitivity. Moreover, heat induced epitope retrieval (HIER) did not affect the differential immunohistochemical outcomes. Our analysis indicates that outcomes of A{beta} immunohistochemistry highly depends on the antibody used in the study.

REST elevation-dependent chromatin remodeling and alternative Grk6 transcript synthesis hyperactivates Cxcr4-Sdf1 signaling in cerebellar granule cell progenitors
RE1 Silencing Transcription Factor (REST) is a repressor of transcriptional initiation of genes involved in neurogenesis. Here, we show that conditional REST elevation in cerebellar granule cell progenitors (CGNPs) of RESTTG mice perturbed foliation, increased cell migration, and sustained C-X-C motif receptor 4 (Cxcr4) signaling, a pathway key to postnatal CGNP migration. Mechanistic studies uncovered a novel role for REST in controlling transcript diversity and exon skipping in CGNPs. Alternative transcript expression was detected in known Cxcr4 signaling regulator, G-protein-coupled receptor kinase-6 (Grk6). Further analysis of Grk6 isoform expression revealed an upregulation of a transcript lacking exon 10a (Grk6-207) in RESTTG CGNPs. Grk6-207 expression in wildtype CGNPs hyperactivated Cxcr4 signaling and increased chemotaxis. Structural modeling of Grk6-207 predicted changes in active site conformation and interactions with Cxcr4 and {beta}-Arrestin-1, supporting impairment of Cxcr4 signaling desensitization. Interestingly, REST elevation promoted increased chromatin accessibility at the exon10a-10b junction and exon 10a exclusion. Integrated multiomic analyses identified the enhancer of zeste (Ezh2) as a potential mediator of alternative transcript generation which demonstrated increased occupancy at the exon10a-10b locus in RESTTG CGNPs. Pharmacological inhibition of Ezh2 downregulated Grk6-207, confirming a role for Ezh2 in Grk6 exon10a exclusion and the increased migration in RESTTG CGNPs.

Resting-state functional MRI derivatives: A dataset derived from the The Comprehensive Assessment of Neurodegeneration and Dementia Study
Resting-state functional connectivity (RSFC) holds promise for the detection and characterisation of dementia. The Comprehensive Assessment of Neurodegeneration and Dementia (COMPASS-ND) Study, by the Canadian Consortium on Neurodegeneration in Aging (CCNA), provides a unique resource to study deeply phenotyped neurodegenerative conditions. We present RSFC derivatives for 784 participants (data release 7 of the cohort) who were either cognitively unimpaired or diagnosed primarily with Alzheimer's disease (AD), mixed dementia (AD with a vascular component), mild cognitive impairment (MCI), vascular MCI, frontotemporal dementia, Parkinson's disease with or without MCI or dementia, Lewy body disease or subjective cognitive impairment. Functional MRI scans were preprocessed using fMRIPrep, and time-series and whole-brain connectomes generated using three atlases at multiple resolutions, denoised using seven different techniques. High-motion artifacts were managed using a liberal quality control threshold appropriate for an older clinical population, resulting in data from 680 participants. These derivatives are made available to the research community to accelerate research on RSFC biomarkers of neurodegenerative disease, reducing duplication of effort, saving computational resources, and improving standardisation across studies.

Perceiving surface colour requires attention
Colour constancy refers to our ability to distinguish changes in surface properties from changes in the properties of light illuminating the scene. The apparent ease with which we can tell that objects do not change colour, for example, when moving from sunlight to the shade, belies the complexity of solving this ill-constrained problem. Although there is a substantial body of work testing which image cues might be used to accomplish this, there is surprisingly little known of how the brain performs this computation. Here, we tested a fundamental aspect of this perceptual process: whether it requires attention. We measured visual search times for both surface colour (requiring separation of surface and illuminant properties) and 'raw', colorimetric colour (which does not). We found a clear difference between the two: visual search for colorimetric colour was fast and near-parallel, while search for surface colour was slow and consistent with the serial deployment of attention. That is, search times suggest that the perceptual separation of surface and illuminant properties in colour constancy may require an attention-based process analogous to perceiving conjunctions of simple features in 'feature binding'. Colour discrimination thresholds suggested that while colorimetric colour detection is fast and parallel, once attention was directed to these stimuli and perceptual scission occurs, colorimetric colour information was discarded by the visual system. These results offer important new insights into the sequence of processes the brain uses to accomplish colour constancy.

Multimodal lesion mapping in affective blindsight reveals dual amygdala and superior temporal sulcus contributions to nonconscious emotion processing
Affective blindsight, the capacity to discriminate emotional stimuli despite bilateral damage to the primary visual cortex (V1) and without conscious awareness, offers a unique model of non-conscious visual processing. Subcortical pathways involving the pulvinar and amygdala have been proposed, but putative cortical contributions remain unclear. We examined 182 patients, including 31 with bilateral V1 lesions. Among these, 15 had cortical visual loss and 7 showed affective blindsight. Using behavioral testing, lesion symptom mapping, and tractography, we found that preserved pulvinar connectivity with both the posterior superior temporal sulcus (STS) and the amygdala is necessary for affective blindsight. These findings provide causal evidence for a multi-route architecture, identifying the pulvinar-STS pathway, alongside the pulvinar-amygdala pathway, as a critical substrate for non-conscious affective processing.

A spatially-resolved human brain proteome atlas for understanding function and disease
While the brain performs specialized functions across distinct regions, the spatial organization of the human brain proteome remains largely uncharted. Here we present a comprehensive spatially-resolved proteome atlas of the human brain, analyzing over two thousand MRI-guided locations across four individuals. Proteome analysis integrated with transcriptomics reveals extensive post-transcriptional regulation, with cortical regions showing markedly higher protein diversity than transcript. Unsupervised molecular clustering defines distinct brain territories that transcend anatomical boundaries, instead reflecting metabolic demands and functional specialization patterns. Application to epilepsy brain tissue uncovered disrupted astrocyte metabolism, protein homeostasis and therapeutic targets including the seizure-associated purinergic receptor P2RX7. This resource bridges molecular and systems neuroscience to accelerate neurological drug discovery.

Cardiac activity impacts spinal cord excitability. A Call to Return to the Roots
The heart continuously shapes neural processing and behavior through cardiac-brain interactions. While cortical excitability fluctuations and their role in cardiac-dependent cognitive and sensorimotor phenomena have been extensively studied, the temporal dynamics and contribution of spinal excitability oscillations across the cardiac cycle remain poorly characterized. In this study, we examine whether motor evoked potentials elicited by magnetic stimulation of the spinal cord are modulated by the cardiac cycle phase in healthy participants. Real-time adapting ECG-triggered stimulation enabled precise targeting of five phases across the cardiac cycle. Spinal excitability was significantly phase-dependent, with MEPs peaking during late diastole. MEPs amplitude was also found to be modulated by preceding cardiac intervals, where shorter intervals predict stronger diastolic facilitation. These findings establish that spinal excitability is rhythmically modulated by the cardiac cycle, potentially through blood pressure-mediated mechanisms. Notably, the diastolic facilitation observed here contrasts with previously reported motor cortex excitability profiles, indicating a non-synchronous cardiac modulation of spinal versus cortical excitability. These results may benefit neuromodulation approaches for motor and psychiatric disorder treatment and emphasize the critical importance of including spinal measures in future heart-brain interaction studies.

Establishment of spinocerebellar ataxia type 34 model mice accompanied by early glial activation and degeneration of cerebellar neurons
Spinocerebellar ataxia type 34 (SCA34) is an autosomal dominant neurodegenerative disease primarily characterized by progressive cerebellar atrophy and ataxia, frequently accompanied by cognitive dysfunction and erythrokeratodermia variabilis. In 2014, missense mutations in the gene encoding elongation of very long chain fatty acids protein 4 (ELOVL4) were identified as the causative gene for SCA34. ELOVL4, which is involved in the synthesis of very long chain fatty acids, ELOVL4 is highly expressed in the cerebellum compared to other brain regions, with predominant expression in neurons. We attempted to establish a mouse model of SCA34 by expressing mutant ELOVL4 in cerebellar neurons using adeno-associated virus (AAV) vectors and to elucidate the underlying pathogenic mechanisms. Expression of W246G mutant ELOVL4 successfully induced progressive motor dysfunction beginning at two weeks post-AAV vector injection. Immunohistochemical analyses revealed that the degeneration of cerebellar Purkinje cells and neurons in the deep cerebellar nuclei (DCN) paralleled the observed motor decline. Importantly, microglial activation was detected in the molecular layer of the cerebellar cortices and the DCN prior to the onset of both neurodegeneration and motor dysfunction. Furthermore, after the onset of motor symptoms, the SCA34 model mice exhibited decreased synaptic inputs from climbing fibers to Purkinje cells, as well as reduce inputs from Purkinje cells to DCN neurons. These findings suggest that early microglial activation and the resulting synaptic disturbance are critical preceding events that lead to the progressive cerebellar neurodegeneration and motor dysfunction observed in this SCA34 mouse model.

PHOX2B polyalanine repeat mutation has a profound impact on the transcriptome of neuronal progenitor cells in Haddad syndrome
Mutation in paired-like homeobox 2B (PHOX2B) is used as the diagnostic marker of Haddad syndrome (HS). The mutant gene/protein afflict neural crest cells during embryonic development which leads to congenital central hypoventilation syndrome (CCHS) and Hirschsprung's disease (HSCR). Previous studies on HS and CCHS have mainly focused on the conformational dynamics of the mutant protein and have remained controversial. Here we performed RNA-sequencing on the patient derived neuroepithelial stem cells (NESCs), pertinent to the neurodevelopmental phenotype in HS, and found that the PHOX2B-PARM has a profound impact on the transcriptional profile of the cells. The single copy of PHOX2B-PARM in heterozygote cells were leading to >10 fold differentially expressed genes. In the patient cells there was a significant enrichment of genes related to neuronal development and synapse organization mainly driven by L1CAM interactions and synaptogenesis signaling pathway. Our result not only highlight the use of a suitable model of HS but also provide a clear path for future experimental validation and downstream targets with potential therapeutic values.

Increased attentive use leads to more idiosyncratic functional connections
Experience is thought to modify neural connections to adapt the network to be more optimal for the environment. Given the brains complexity, multiple network changes could each move the system toward optimality. Standard methods ignore this multiplicity and examine each connection independently; these studies have often shown considerable inter-individual variability and modest effects (1). Here, we take a different strategy, determining how a whole-brain connection pattern differs from the typical pattern, that is, how idiosyncratic the pattern is. We examined how the idiosyncrasy of whole brain connection patterns varies with frequency of the use of that part of cortex for attention-demanding tasks, focusing on central versus peripheral vision in healthy individuals (where individuals use central vision more frequently for attention-demanding tasks). We found that the whole-brain pattern of functional connections to the cortical representations of central vision is idiosyncratic, whereas patterns of connections to representations of peripheral vision were very similar person-to-person. In a second set of analyses, we examined the brains of people with central vision loss who use a portion of peripheral vision (called the preferred retinal locus) more frequently for attention-demanding tasks in their daily lives. The cortical representation of the preferred retinal locus exhibits more idiosyncratic connections, compared to a control brain region, or compared to the same brain region in matched control participants with healthy vision. These results are consistent with the hypothesis that increased attentive use of a brain area results in idiosyncratic patterns of whole brain connections.

Time-Dependent Facilitation of Homologous Actions
Unimanual actions can interfere with or facilitate similar actions performed with the opposite hand, especially when in close temporal proximity. Across three sequential button-press experiments, we tested how effector homology - anatomical similarity between fingers - and temporal delays between actions shape these effects. Specifically, we examined whether a priming action altered the reaction time (RT) of a subsequent action. Compared with unimanual RTs, we indexed slowing of the RT from the second action as interference, and quickening as facilitation. Priming with homologous actions (e.g., index finger-index finger) produced interference at short intervals ([≤] 200ms) but transitioned to facilitation at longer intervals ([≥] 400ms). Priming with non-homologous actions (e.g., little finger-index finger) also produced interference at short intervals, but never resulted in facilitation. Critically, these patterns emerged whether the priming actions were performed with the opposite or the same hand, indicating that interference and facilitation do not depend on interhemispheric dynamics. Our results reveal a previously undocumented time-dependent shift from interference to facilitation that is specific to homologous actions, challenging models that explain the interference between parallel actions solely by competitive interhemispheric dynamics or central bottleneck processes. We propose that facilitation and interference flexibly coexist, and are shaped by effector homology and timing. These findings extend current models of bimanual coordination and highlight new opportunities for enhancing motor performance and neurorehabilitation.

Cingulate-centered flexible control: physiologic correlates and enhancement by internal capsule stimulation
The flexible deployment of cognitive control is essential for adaptive functioning in dynamic environments given limited cognitive resources. That flexibility depends on rapid detection and resolution of control-prediction errors (CPEs) when current demands diverge from the control plan. Deficits in control and control flexibility are common in psychiatric disorders, yet targeted interventions are limited by incomplete circuit-level understanding and limited means for modulating control circuits . We analyzed two intracranial electroencephalography datasets (one with brief internal capsule stimulation, ICS) to identify a human neurocomputational mechanism for CPE resolution and to test its modifiability. A third dataset of patients receiving internal capsule deep brain stimulation (IC DBS) assessed clinical relevance of modifying CPE-related processes. Phase-amplitude coupling (PAC) anchored to the {theta} phase of right rostral anterior cingulate cortex (rACC-R), especially {theta}- coupling between rACC-R and nodes of the cognitive control network (dorsolateral prefrontal cortex, dlPFC; dorsal ACC, dACC), was associated with faster CPE resolution. An adaptive drift-diffusion model indicated that ICS improves control flexibility specifically under high CPE, and mediation analyses showed that this behavioral improvement is mediated by CPE-dependent increases in rACC-R {theta}-centered PAC. In a psychiatric cohort (N=14; primarily treatment-resistant depression, TRD) with IC DBS, enhanced control flexibility, rather than CPE-independent general cognitive control, was strongly associated with clinical response (AUC = 0.90), suggesting both a behavioral flexibility index and rACC-R PAC as candidate biomarkers for DBS optimization. These findings identify a rACC-centered, {theta} phase-based coordination of the cognitive control network as a neurocomputational substrate of flexible control. They demonstrate that capsule stimulation selectively augments this substrate when flexibility is required, and establish flexibility, rather than general control, as the feature that tracks therapeutic benefit in TRD. Together, they suggest actionable biomarkers to guide, personalize, and potentially enable closed-loop neuromodulation for disorders marked by cognitive rigidity.

KF/parabrachial complex PACAP - glutamate pathway to the extended amygdala couples rapid autonomic and delayed endocrine responses to acute hypotension
The calyx of Held is a giant axo-somatic synapse classically confined to the auditory brainstem. We recently identified morphologically similar calyx-like terminals in the extended amygdala (EA) that arise from the ventrolateral parabrachial complex and co-express PACAP, CGRP, VAChT, VGluT1, and VGluT2, targeting PKCdelta+/GluD1+ EA neurons. Here we asked whether this parabrachial - EA pathway participates in compensation during acute hypotension. In rats given hydralazine (10 mg/kg, i.p.), we quantified Fos protein during an early phase (60 min) and a late phase (120 min). Early after hypotension, Fos surged in a discrete subpopulation of the parabrachial Kolliker - Fuse (KF) region and in the EA, whereas magnocellular neurons of the supraoptic and paraventricular nuclei (SON/PVN) remained largely silent. By 120 min, magnocellular SON/PVN neurons were robustly Fos-positive. Confocal immunohistochemistry showed that most Fos+ PKCdelta/GluD1 EA neurons were encircled by PACAP+ perisomatic terminals (80.8%), of which the majority co-expressed VGluT1 (88.1%). RNAscope in situ hybridization further identified a selective KF population co-expressing Adcyap1 (PACAP) and Slc17a7 (VGluT1) that became Fos-positive during the early phase. Together these data indicate that a KFPACAP/VGluT1 projection forms calyceal terminals around PKCdelta/GluD1 EA neurons, providing a high-fidelity route for rapid autonomic rebound to falling blood pressure, while slower endocrine support is subsequently recruited via vasopressinergic magnocellular activation. This work links multimodal parabrachial output to temporally layered autonomic - neuroendocrine control.

Brain-Wide Subnetworks within and between Naturally Socializing Typical and Autism Model Mice
Social interaction is inherently asymmetric, requiring coordinated activity between non-homologous brain regions across individuals. However, the brain-wide dynamics underlying such inter-brain coordination remain poorly understood. We used multi-fiber photometry to simultaneously record from 24 brain regions in pairs of freely interacting mice, including a model of autism. Social interactions evoked widespread, dynamic activity across brains, with inter-brain synchrony, especially between non-homologous areas, exceeding intra-brain synchrony, particularly in dominant mice. Network analysis revealed three subnetworks: (1) Emotional, intra-brain enhanced in subordinates; (2) Sensory, spanning both mice; (3) Decision/consolidation, linking dominant prefrontal cortex to subordinate hippocampus. These subnetworks encoded dominance, identity, and interaction roles, and followed a clear temporal sequence around social events. In an autism model, socially evoked activity was hyperactive displaying mostly within brain synchrony but lacked inter-brain synchrony. Our results uncover dynamic inter-brain circuits as a hallmark of social behavior and reveal their disruption in autism.

Sustained alpha oscillations serve attentional prioritization in working memory, not maintenance
Recent theory on the neural basis of working memory (WM) has attributed an important role to "activity-silent" mechanisms, suggesting that sustained neural activity might not be essential in the retention of information. This idea has been challenged by reports of ongoing neural activity in the alpha band during WM maintenance, however. The precise role of these alpha oscillations is unclear: Do they reflect attentional prioritization of stored information, or do they serve as a general maintenance mechanism, for instance to periodically refresh synaptic traces? To address this, we designed a visual WM task involving two memory items, one of which was prioritized for recall. The task included both a short (1 s) and a long (3 s) delay intervals between encoding and retrieval. The long delay was implemented to provide a more decisive test of WM maintenance, providing a point in time when any initially silent synaptic traces would likely need to be refreshed as well. Time-resolved decoding analyses revealed that both prioritized and deprioritized items were initially decodable following stimulus presentation. However, only the prioritized item exhibited sustained decodability throughout the delay, particularly in the long delay condition, where it transitioned into a stable coding scheme. This prolonged representation was selectively supported by induced alpha power, which reliably tracked the prioritized item, but not the deprioritized one. Impulse-based decoding further confirmed this asymmetry, highlighting a selective reactivation of the deprioritized item only upon contextual relevance. Together, these findings suggest that sustained alpha-band activity reflects attentional prioritization, rather than general memory maintenance. Unattended, non-prioritized items appear to transition into an activity-silent state, consistent with models of synaptic storage in WM.

Longitudinal Assessment of Fluorescence Stability Shows Fluorescence Intensity Decreases Over Time: Implications for Fluorescence Microscopy Studies
Immunohistochemistry (IHC) is one of the most widely used techniques across basic, translational, and clinical sciences. Key considerations need to be made to achieve reliable and robust IHC staining, however what has been understudied is the stability of IHC signal intensity over time. Changes in signal intensity over time have significant implications for data analysis and interpretation and ultimately impact scientific conclusions. In order to explore changes in IHC signal, the stability of fluorescence intensity was assessed over the course of six weeks using widefield or confocal microscopy. Results indicate that fluorescence intensity can decrease over this time course and that whether this decrease occurs and to what extent is influenced by the selection of the primary antibody as well as that of the secondary antibody, primary-secondary antibody combination, and utilization of chemical staining versus IHC staining. This investigation reinforces best practices for imaging fluorescent staining to ensure accurate and reliable data collection, be it for cell counting, assessing protein expression levels, or marker colocalization.

The Spiking Tolman-Eichenbaum Machine: Emergent Spatial and Temporal Coding through Spiking Network Dynamics
The hippocampal-entorhinal system supports spatial navigation and memory by orchestrating the interaction between grid cells and place cells. While various models have reproduced these patterns, many rely on predefined connectivity or fixed weights and lack mechanisms for learning or biologically realistic temporal dynamics. The Tolman-Eichenbaum Machine (TEM) has recently gained attention as a unified generative model that explains the emergence of both grid and place cells through learning. However, existing TEM implementations rely on rate-based units and simplified architectures, which limit their biological plausibility. Here, we introduce the Spiking Tolman-Eichenbaum Machine (Spiking TEM)--a spiking neural network model that extends the original TEM with spike-based computation and an anatomically inspired hippocampal-entorhinal architecture. Our model learns grid-like codes in the entorhinal module and context-specific place codes in the hippocampal module, while also exhibiting key temporal coding phenomena observed in electrophysiological recordings, including phase locking of spikes to theta oscillations and phase precession. Furthermore, the model gives rise to predictive grid cells in layer III of the entorhinal cortex, which prospectively encode upcoming spatial positions. These results demonstrate that structured spatial representations and temporally precise coding schemes can emerge from biologically plausible spike-based learning and dynamics, offering a unified framework for understanding spatial and temporal coding in the hippocampal-entorhinal circuit.

Attention and Explicit Knowledge Drive Predictive Sharpening in Early Visual Cortex
Perception is increasingly understood as an inferential process, whereby what we perceive results from the integration of sensory inputs with expectations derived from prior knowledge. Top-down predictions have been shown to alter the encoding of sensory information, from early to late stages of processing. Yet, how such predictions shape neural representations in sensory cortices remains debated. Competing accounts suggest that predictions either sharpen neural representations by enhancing selectivity or dampen activity by broadly suppressing stimulus-driven responses. In a preregistered fMRI study, we tested whether these effects depend on the level of attentional engagement and explicit knowledge of predictive associations. Using a multisensory fMRI paradigm with concurrent but independent visual and auditory probabilistic associations (75% validity) and manipulated attention, we investigated predictive effects in human early visual cortex. Consistent with prior work, expected visual stimuli elicited reduced BOLD activity. Critically, sharpening of expected visual stimuli occurred exclusively when visual inputs were attended and the concurrently presented auditory inputs expected. In addition, the magnitude of the sharpening of visual representations correlated positively with participants' explicit knowledge of the visuo-predictive associations. These findings highlight the key roles of attention and explicit knowledge in promoting predictive sharpening and underscore the need to study predictive processing in more ecologically valid, multisensory contexts.

Hyperexcitability in Alzheimers Disease triggers a compensatoryneuroprotective response via TREK1
Alzheimers Disease (AD) is marked by early hippocampal and neocortical accumulation of amyloid-beta 42 oligomers, driving neuronal hyperactivity and synaptic dysfunction years before symptom onset. While two-pore domain leak potassium channels like TREK1 provide neuroprotection against hyperexcitability, their role in AD remains unknown. Here, we discover an activity-dependent upregulation of TREK1 in AD transgenic mice (3xTg and APP/PS1) and cultured hippocampal/cortical neurons, triggered by amyloid-beta 42 oligomers -induced hyperactivity. Mechanistically, we show that increased intracellular calcium activates adenylate cyclase 1/8 (AC1/8), initiating a cAMP-PKA signalling cascade that enhances the expression of chromatin regulator CTCF. This increased CTCF in turn enhances the expression of TREK1 both in vitro and in AD transgenic mice. Using calcium imaging, patch clamp electrophysiology, immunohistochemistry assays, we demonstrate that the upregulation of TREK1 serves as a critical brake on neuronal hyperexcitability and is essential for restoring synaptic balance and mitigating AD pathology. Our study identifies a multi-step signalling cascade triggered by amyloid-beta 42 oligomers leading to upregulation of TREK1 that functions as an essential compensatory mechanism for neuronal survival in early AD.

Presynaptic Release Probability Determines the Need for Sleep
Sleep is universal among animals with synapses, yet the synaptic functions determining the need for sleep remain elusive. By directly measuring synaptic transmission at anatomically defined synapses in Drosophila, we found that synaptic strength remained stable or declined after sleep deprivation in a circuit-specific manner. In contrast, presynaptic release probability (Pr) consistently decreased with sleep loss across circuits and species, stemming from reduced Ca2+ influx or weakened vesicle-channel coupling at presynaptic terminals, and recovered after sleep. Bidirectional manipulations of Pr altered sleep pressure, establishing a causal relationship between presynaptic function and sleep need. Non-synaptic sleep-regulatory signaling pathways consistently modulate Pr but not synaptic strength. Thus, our findings identify Pr, rather than synaptic strength, as the conserved synaptic substrate underlying sleep need.

Autistic traits modulate neural responses to social signals during natural vision
Impairments in social perception, a hallmark of autism spectrum disorder (ASD), are also evident at subclinical levels in the general population. However, it remains unclear how such variation in autistic traits modulate neural processing of different types of social information. Here, we investigated whether autistic traits in neurotypical individuals are associated with neural responses to a broad array of social perceptual features during viewing naturalistic stimuli using functional magnetic resonance imaging (fMRI). We also tested the generalizability of these effects across two experiments. Ninety-seven participants completed the Autism Spectrum Quotient (AQ) and watched a set of 96 movie clips and a full movie during an fMRI scan. Intensity of 126 social features in the movie stimuli was continuously annotated by independent observers, and 44 most reliably rated features were used to model neural responses. We examined how consistently the responses to each social feature were dependent on the participant's AQ scores. Replicable AQ-dependent neural responses to social features were found in both datasets. The temporal cortex and especially the superior temporal gyrus (STG), served as a central "hub" where autistic traits consistently modulated responses to social features across datasets. Different AQ subscales also revealed distinct association patterns in other brain regions. These findings indicate that autism-related traits broadly influence neural processing of naturalistic social signals, providing insight into how characteristics of autistic symptoms relate to socioemotional processing.

Identity and functions of monoaminergic neurons in the predatory nematode Pristionchus pacificus reveal nervous system conservation and divergence
Changes in neurotransmitter usage in homologous neurons may drive evolutionary adaptations in neural circuits across animal phylogeny. The predatory nematode Pristionchus pacificus can be used as a model system to examine nervous system evolution by comparing neurotransmitter expression with that of C. elegans and other nematodes. Here we characterize P. pacificus neurotransmitter expression and function in specific neurons, focusing on its complete set of monoaminergic neurons. We discover patterns of conservation as well as novelties. We examine the roles of monoamines in specific behaviors using neurotransmitter synthesis and vesicular transporter mutants, finding possible differences in the control of host-finding and dispersal behavior.