bioRxiv Subject Collection: Neuroscience's Journal

Canonical Wnt Signaling Suppresses Brain Endothelial Cell Transcytosis to Maintain Blood-Brain Barrier Integrity
Canonical Wnt signaling is essential for blood-brain barrier (BBB) development and maintenance. However, the subcellular mechanisms underlying this critical regulation have remained elusive. In this study, we use a physiological paradigm examining an early phase of acutely attenuated canonical Wnt signaling in adult brain endothelial cells (ECs) to investigate how the pathway regulates BBB integrity. Following canonical Wnt signaling attenuation via EC-specific knockout of {beta}-catenin, we find that there is increased transcytosis in brain ECs, including a striking diversity of morphologically distinct vesicles, indicating multiple pathways are involved. In addition, we find that although the molecular composition of tight junctions (TJs) is altered following canonical Wnt signaling attenuation, such that Claudin-5 and ZO-1 expression is downregulated, TJs remain impermeable to molecules as small as 1.9 kDa. These findings reveal previously underappreciated role of Wnt signaling in regulating brain EC transcytosis and help illuminate subcellular mechanisms of BBB maintenance in adulthood, which is crucial for improving delivery of therapeutics to the brain.

Melatonin Enhances Sleep via MT1-Driven Activation of Slo1 in Suprachiasmatic Nucleus Neurons
Melatonin is known to promote sleep, but its underlying molecular mechanisms remain poorly understood. Using CBA/CaJ mice, a strain capable of melatonin synthesis, we explored the roles of the BK channel (Slo1) and the melatonin receptor MT1 in regulating sleep behavior and action potentials in the suprachiasmatic nucleus (SCN). Global knockout of Slo1 or MT1 reduced REM and NREM sleep, increased wakefulness, and broadened action potentials while abolishing afterhyperpolarization in SCN neurons. These effects were primarily or exclusively observed during the subjective daytime, when mice are less active. Consistent with this, Slo1 expression in the SCN was markedly higher during the day than at night. Slo1 knockout mice also exhibited pronounced seizure activity. Through deletion analyses, we identified key domains in MT1 and Slo1 that are essential for their physical interaction. Together, these findings suggest that melatonin promotes sleep by activating Slo1 in the SCN through an MT1-mediated signaling pathway.

Neurocomputational underpinnings of suboptimal beliefs in recurrent neural network-based agents
Maladaptive belief updating is a hallmark of psychiatric disorders, yet its underlying neurocomputational mechanisms remain poorly understood. While Bayesian models characterize belief updating in decision-making, they do not explicitly model neural computations or neuromodulatory influences. To address this, we developed a recurrent neural network-based reinforcement learning framework to investigate decision-making deficits in psychiatric conditions, using schizophrenia as a test case. Agents were trained on a predictive inference task commonly used to assess cognitive deficits found in schizophrenia, including under-updating beliefs in volatile environments and over-updating beliefs in response to uninformative cues. The task thus included two conditions: (1) a change-point condition requiring adaptation in a volatile environment and (2) an oddball condition requiring resistance to outliers. We modeled these deficits by systematically manipulating key hyperparameters associated with specific neural theories: reward prediction error (RPE) discounting and scaling (reflecting diminished dopamine responses), network dynamics disruption (reflecting impaired working memory), and rollout buffer size reduction (reflecting decreased episodic memory capacity). These manipulations reproduced schizophrenia-like decision-making impairments and revealed that suboptimal agents exhibited fewer unstable fixed points near network activity in the change-point condition, suggesting reduced computational flexibility. This framework extends computational psychiatry by linking cognitive biases to neural dysfunction and provides a mechanistic approach to studying decision-making impairments in psychiatric disorders.

Changes in Motor Unit Activity of Co-activated Muscles During Dynamic Force Field Adaptation
Muscle co-contraction plays a critical role in motor adaptation by minimizing movement errors and enhancing joint stability in novel dynamic environments. However, the underlying changes in motor unit (MU) activity within co-activated muscles during adaptation remain largely unexplored. To investigate this, we employed advanced electromyography sensor arrays and signal processing to examine MU activation in the triceps brachii (agonist) and biceps brachii (antagonist) during a reaching task under force-field perturbation. Our results revealed a gradual reduction in movement errors and an increase in velocity with adaptation, accompanied by a decrease in muscle co-contraction from early to late adaptation phases. This reduction was primarily driven by increased triceps activity, while biceps activity remained unchanged throughout the adaptation process. At the MU level, recruitment, amplitude, and firing rate increased in both muscles during adaptation compared to baseline (without force-field perturbation). However, from early to late adaptation phases, triceps MU amplitude continued to increase, while its firing rate stabilized, suggesting a shift in force generation strategy. In contrast, biceps MU activity remained stable throughout the adaptation. These findings indicate that the reduction in co-contraction during motor adaptation is likely mediated by a shift in motor unit control strategy within the agonist muscle. The increased reliance on MU amplitude modulation rather than firing rate in later adaptation may represent a mechanism for optimizing force production while maintaining movement accuracy and joint stability in dynamic environments.

Endothelin-converting enzyme 2 differentially regulates kappa opioid receptor trafficking and function
Following activation by endogenous opioid peptides, mu and delta opioid receptors have been shown to undergo differential internalization and recycling; the rate and extent of recycling but not internalization was found to be regulated by the endocytic peptide converting enzyme, ECE2. This study focuses on kappa opioid receptors (KOR) and the ability of endogenous opioid peptides released by post-translational processing of prodynorphin and proenkephalin to induce KOR and ECE2 internalization/recycling, and how ECE2 modulates these processes. Using a proximity-based ligation assay we show that KOR and ECE2 are in close proximity to facilitate co-internalization. In addition, we find that treatment with longer opioid peptides induces fast and robust internalization and recycling of ECE2 at a rate and extent comparable to that of KOR. Next, we directly examined the role of ECE2 in modulating KOR recycling. We find that ECE2 inhibition significantly attenuates KOR recycling. Finally, we examined the role of ECE2 in modulating KOR signaling and find that resensitization of KOR by peptides that are substrates of ECE2 are attenuated by ECE2 inhibition. Taken with the differential expression of ECE2 in the brain (relatively high expression in midbrain & hypothalamus and low expression in the striatum & hippocampus), these results highlight a pivotal role for ECE2 in differentially modulating KOR function.

The flexible contribution of cortical area V4 to visual perception
Cortical area V4 is thought to be critical for visual object recognition. It contains millimeter-scale domains in which neurons are highly selective for stimulus features such as shape, motion, and color. In theory, many different stimuli can be decoded from neural activity in each of these domains, but whether the brain actually makes use of this information is unknown. Here we have tested this hypothesis, using reversible inactivation of V4 in non-human primates performing a shape discrimination task. We find that training with the stimuli preferred by a particular domain causes the brain to develop a simple readout that ignores much of the information in the V4 neural population. In contrast, training with other stimuli leads to a more distributed readout of the V4 population. Thus, specialized cortical domains do not necessarily have a fixed behavioral function, but they can powerfully influence the learning of new perceptual tasks.

Focal Infrared Neural Stimulation Propagates Dynamical Transformations in Auditory Cortex
Significance: Infrared neural stimulation (INS) has emerged as a potent neuromodulation technology, offering safe and focal stimulation with superior spatial recruitment profiles compared to conventional electrical methods. However, the neural dynamics induced by INS stimulation remain poorly understood. Elucidating these dynamics will help develop new INS stimulation paradigms and advance its clinical application. Aim: In this study, we assessed the local network dynamics of INS entrainment in the auditory thalamocortical circuit using the chronically implanted rat model; our approach focused on measuring INS energy-based local field potential (LFP) recruitment induced by focal thalamocortical stimulation. We further characterized linear and nonlinear oscillatory LFP activity in response to single-pulse and periodic INS and performed spectral decomposition to uncover specific LFP band entrainment to INS. Finally, we examined spike-field transformations across the thalamocortical synapse using spike-LFP coherence coupling. Results: We found that INS significantly increases LFP amplitude as a log-linear function of INS energy per pulse, primarily entraining to LFP {beta} and {gamma} bands with synchrony extending to 200 Hz in some cases. A subset of neurons demonstrated nonlinear, chaotic oscillations linked to information transfer across cortical circuits. Finally, we utilized spike-field coherences to correlate spike coupling to LFP frequency band activity and suggest an energy-dependent model of network activation resulting from INS stimulation. Conclusions: We show that INS reliably drives robust network activity and can potently modulate cortical field potentials across a wide range of frequencies in a stimulus parameter-dependent manner. Based on these results, we propose design principles for developing full coverage, all-optical thalamocortical auditory neuroprostheses.

Hyperplastic Growth, Not Hydrostatic Distension, in Endolymphatic Hydrops in Humans Challenges the Classic View of Meniere's Disease
Meniere's disease (MD), a degenerative inner ear disorder, is characterized by debilitating episodic vertigo "attacks" and hearing fluctuations, progressing to permanent sensory impairment. The prevailing dogma attributes these symptoms to an abnormal inner ear fluid buildup, known as endolymphatic hydrops (EH), with concomitant rise of fluid pressure and repetitive microtrauma to sensory epithelia. However, this pressure-based mechanism lacks direct experimental evidence and fails to explain key clinical aspects of MD - exposing a critical gap in our disease understanding. To revisit the fundamental nature of EH, we performed 3D reconstructive, machine-learning-enhanced histological analyses and immunohistochemistry on human postmortem inner ear specimens. Contrary to the classic theory, EH-affected epithelia showed no signs of pressure-induced change. Instead, we observed an up to four- to seven-fold increase in epithelial cell number (hyperplasia) in both early and advanced EH stages. Quantification of the hyperplastic epithelial surface area, as well as immunohistochemical localization of key fluid homeostasis-associated proteins in the hyperplastic epithelium suggest this epithelial hyperplasia may actively compensate for cell loss in the endolymphatic sac, a key site of MD pathology. These findings challenge the conventional view of EH as solely a pathological pressure phenomenon, instead revealing an unexpected massive cellular expansion of these epithelia, consistent with a coordinated compensatory cellular response aimed at preserving inner ear fluid homeostasis and function in a compromised environment. This paradigm shift introduces dual beneficial and detrimental roles for EH, and suggests new therapeutic avenues for MD focused on promoting compensatory tissue repair while preventing maladaptive remodeling.

Overlooked features lead to divergent neurobiological interpretations of brain-based machine learning biomarkers
A central objective in human neuroimaging is to understand the neurobiology underlying cognition and mental health. Machine learning models trained on brain connectivity data are increasingly used as tools for predicting behavioral phenotypes 1,2, enhancing precision medicine 3,4, and improving generalizability compared to traditional MRI studies 5. However, the high dimensionality of brain connectivity data makes model interpretation challenging 6. Prevailing practices within the field rely on sparsely selected brain connectivity features, implicitly interpreting identified feature networks as uniquely representative of a given phenotype while overlooking others. Here, we show that commonly overlooked brain connectivity features can achieve similar prediction accuracies while yielding markedly different neurobiological interpretations. Using four large-scale neuroimaging datasets spanning over 12,000 participants and 13 outcomes, we demonstrate that this phenomenon is widespread across cognitive, developmental, and psychiatric phenotypes. It extends to both functional connectivity (fMRI) and structural (DTI) connectomes and remains evident even in external validation. These findings suggest that common practices may lead to feature overinterpretation and a misrepresentation of the neurobiological bases of brain-behavior associations. Such interpretations present only the "tip of the iceberg" when certain disregarded features may be just as meaningful, potentially contributing to ongoing issues surrounding reproducibility within the field. More broadly, our results point to the possibility that multiple neurobiologically distinct models may exist for the same phenotype, with implications for identifying meaningful subtypes within clinical and research populations.

Effect of MRI Defacing on EEG Forward and Inverse Modeling
Recent years have seen improvements in facial recognition software, which has increased the risk of re-identification of patients' structural neuroimaging scans, e.g. obtained from magnetic resonance imaging (MRI). Thus, an anonymization procedure known as defacing has become the norm when publicly sharing patients' scans. Defacing removes some of the facial features from the data, making it improbably to re-identify a patient from a 3D rendering of the image. However, certain tasks, such as localization of the sources of electroencephalographic (EEG) signals, require the creation of individual electrical volume conductor models of the human head from structural MRI data. Defacing could affect the co-registration of MRI and EEG sensor positions and, more importantly, the model of electrical current flow itself. This study quantifies and maps the effect of defacing on individual volume conductor models and the localization accuracy of inverse solutions based on these models in a sample of ten subjects with known ground-truth (non-defaced) anatomy. Boundary and finite element modeling approaches (B/FEM) are compared.

Tau-Associated Neuronal Loss in the Intermediate Nucleus of the Human Hypothalamus (VLPO Analog): Unveiling the Basis of NREM Sleep Dysfunction in PSP and Alzheimer's Disease
Sleep disturbances are prevalent in Alzheimer's disease (AD) and Progressive Supranuclear Palsy (PSP), often exacerbating disease progression. Understanding the neuropathological basis of these disturbances is essential for identifying potential therapeutic targets. This study investigates the intermediate nucleus (IntN) of the human hypothalamus, a key sleep regulating region analogous to the rodent ventrolateral preoptic area (VLPO), to assess neuronal loss and tau pathology in AD and PSP. Using postmortem brain tissue, we applied unbiased stereology to quantify galanin-expressing neurons and phosphorylated tau (p-tau) accumulation. Among 26 cases analyzed, both AD and PSP exhibited significant neuronal loss in the IntN, with PSP showing the most pronounced reduction (84.9% fewer neurons than healthy controls [HC]). In AD, neuronal loss correlated with Braak staging, with late-stage AD cases (Braak 5/6) demonstrating a 76.9% reduction in galanin-expressing neurons compared to HC, while non-galanin neurons exhibited a more moderate decline (45.7%). In PSP, extensive neuronal loss precluded a clear assessment of p-tau burden. These findings suggest a differential neuronal vulnerability to tau pathology across diseases, aligning with distinct sleep disturbances observed in each condition. PSP, characterized by severe insomnia despite preserved wake-promoting neurons, may be explained by the near-total loss of NREM sleep-regulating neurons. In contrast, AD exhibits a progressive decline in both wake- and sleep-promoting neurons, contributing to excessive daytime sleepiness and sleep fragmentation. This study provides critical insights into the selective neuronal vulnerabilities underlying sleep dysfunction in tauopathies, emphasizing the need for targeted interventions to mitigate sleep disturbances in these disorders.

Emotional arousal enhances narrative memories through functional integration of large-scale brain networks
Emotional events tend to be vividly remembered. While growing evidence suggests that emotions have their basis in brain-wide network interactions, it is unclear if and how these whole-brain dynamics contribute to memory encoding. We combined fMRI, graph theory, text analyses, and pupillometry in a naturalistic context where participants recalled complex narratives in their own words. Across three independent datasets, emotionally arousing moments during the narratives were associated with an integrated brain state characterized by increased cohesion across functional modules, which in turn predicted the fidelity of subsequent recall. Network integration mediated the influence of emotional arousal on recall fidelity, with consistent and distinct network interactions supporting the mediation across datasets. Together, these results suggest that emotional arousal enhances memory encoding via strengthening functional integration across brain networks. Our findings advance a cross-level understanding of emotional memories that bridges large-scale brain network dynamics, affective states and ongoing cognition.

How forgiving are M/EEG inverse solutions to noise level misspecification? An excursion into the BSI-Zoo.
Brain source imaging (BSI), also known as source localization, from magneto- and electroencephalographic (M/EEG) data, is a challenging ill-posed inverse problem. Accurate source estimation is sensitive to modeling parameters, such as regularization strength and noise level, where misconfigurations can lead to under- or overfitting. Different BSI methods, however, may vary in their robustness to suboptimal parameter choices. Here we conducted extensive simulations of brain sources superimposed by varying degrees of sensor noise to study the ranges of noise misspecification within which different BSI approaches can still localize well. Using the Earth Mover's Distance (EMD) and other metrics, we compare the performance of smooth linear inverse solutions with that of sparse non-linear Bayesian learning solutions. Additionally, we assess the effectiveness of various noise estimation and cross-validation techniques to select hyperparameters close to those achieving optimal localization. Methods and experiments are made available within the BSI-Zoo Python package.

Astroglial TNFR2 signaling regulates hippocampal synaptic function and plasticity in a sex dependent manner
Astrocytes participate in synaptic transmission and plasticity through tightly regulated, bidirectional communication with pre- and post-synaptic neurons, as well as microglia and oligodendrocytes. A key component of astrocyte-mediated synaptic regulation is the cytokine tumor necrosis factor (TNF). TNF signals via two cognate receptors, TNFR1 and TNFR2, both expressed in astrocytes. While TNFR1 signaling in astrocytes has been long demonstrated to be necessary for physiological synaptic function, the role of astroglial TNFR2 has never been explored. Here, we demonstrate that astroglial TNFR2 is essential for maintaining hippocampal synaptic function and plasticity in physiological conditions. Indeed, GfapcreERT2:Tnfrsf1bfl/fl mice with selective ablation of TNFR2 in astrocytes exhibited dysregulated expression of neuronal and glial proteins (e.g., SNARE complex molecules, glutamate receptor subunits, glutamate transporters) essential for hippocampal synaptic transmission and plasticity. Hippocampal astrocytes sorted from GfapcreERT2:Tnfrsf1bfl/fl mice displayed downregulation of genes and pathways implicated in synaptic plasticity, as well as astrocyte-neuron and astrocyte-oligodendrocyte communication. These alterations were accompanied by increased glial reactivity and impaired astrocyte calcium dynamics, and ultimately translated into functional deficits, specifically impaired long-term potentiation (LTP) and cognitive functions. Notably, male GfapcreERT2:Tnfrsf1bfl/fl mice exhibited more pronounced hippocampal synaptic and cellular alterations, suggesting sex-dependent differences in astroglial TNFR2 regulation of synaptic function. Together, these findings indicate that TNFR2 signaling in astrocytes is essential for proper astrocyte-neuron communication at the basis of synaptic function, and that this is regulated in a sex-dependent manner.

Establishment of a second-generation transgenic marmoset model of polyglutamine disease recapitulating neurological symptoms and pathology
Neurodegenerative diseases, including polyglutamine diseases, remain a major clinical challenge, partly because of limited animal models that recapitulate human disease. Here, we describe a second-generation transgenic marmoset model of spinocerebellar ataxia 3 (SCA3), a polyglutamine disease, which stably expresses expanded CAG repeats in ATXN3. All five offspring of the founder marmoset harbored the transgene with reduced transgene integration sites and without repeat instability or genetic mosaicism, offering improved construct validity. Three of the five marmosets developed progressive motor impairments that segregated into two distinct phenotypes: early onset with rapid progression and late onset with mild progression, accompanied by corresponding patterns in body weight gain and grip strength. Pathological analysis revealed cerebellar Purkinje cell loss, spinal cord neurodegeneration, and widespread intranuclear inclusions. The severity of motor phenotypes correlated with transgene expression levels in disease-relevant brain regions, including the cerebellum, spinal cord, and striatum. By overcoming the common translational limitations of rodent systems, our second-generation model offers a powerful platform for investigating disease mechanisms and testing potential therapeutic interventions. Our results advance the utility of transgenic marmosets as clinically relevant models of neurodegenerative diseases.

Locomotion-dependent use of geometric and body cues in humans mapping 3D space
The ability to represent locations across multiple dimensions of space is a core function of cognitive maps. While the influence of boundary-dependent environmental geometry on spatial representations has been extensively studied in 2D spaces, less is known about the role of boundaries for volumetric spatial memory. Research in humans and other animals has demonstrated distinct processing of the vertical and horizontal spatial dimensions, likely related to species-specific modes of locomotion. Here, we investigate whether different locomotion modes, flying and walking, affect the use of vertical boundaries, leading to possibly distinct volumetric representations. In a Virtual Reality experiment, human participants memorized objects within a symmetric 3D enclosure, and then were asked to replace them in either the familiar or geometrically deformed environments. We found that the flying group exhibited lower vertical than horizontal spatial memory precision, whereas the walking group showed the opposite pattern, an effect related to using their body axis as a vertical 'ruler'. Within deformed environments, object replacements in the flying group followed the predictions from a 3D-extended boundary-vector-cell-like computational model of spatial mapping that treated all boundaries equally, whereas those in the walking condition favored a modified model that prioritized the ground boundary. Our findings suggest that gravity-related movement constraints promote different utilization of geometric and body-related cues, resulting in flexible representations of volumetric space.

Preserving predictive information under biologically plausible compression
Retinal ganglion cells (RGCs) show high convergence onto their downstream projections, which poses a problem for information transfer: how can information be preserved through a synaptic layer that has significantly more inputs than outputs? Lossy compression suggests many efficient, yet computation-agnostic, methods for reading out input stimuli or activity patterns. Focusing on prediction as a ubiquitous computation in the brain, we compare compressions that explicitly retain predictive information to common neural compression frameworks that do not. We find evidence that downstream areas may compress their retinal inputs in a way that allows them to perform optimal predictive computations across many natural scenes. Other sensory systems also exhibit compression in their processing hierarchies, such as at the glomeruli stage in the olfactory system, and we hope that our framework will be useful in cases where it is not yet known how information about a specific computation is maintained under compression.

Premature vision drives aberrant development of response properties in primary visual cortex
Development of the mammalian visual system is thought to proceed in two stages. In the first stage, before birth in primates and before eye opening in altricial mammals, spontaneous activity generated by the retina and cortex shapes visual brain circuits in an activity-dependent but experience-independent manner. In the second stage, visual activity generated by sensory experience refines receptive fields. Here we investigated the consequences of altering this sequence of events by prematurely opening one or both eyes of ferrets and examining visual receptive fields in monocular cortex after the closure of the critical period for ocular dominance plasticity. We observed that many cells in animals with prematurely-opened eyes exhibited low-pass temporal frequency tuning and increased temporal frequency bandwidths, and these cells showed slightly increased orientation and direction selectivity index values. Spontaneous activity was greatly elevated in both hemispheres following the premature opening of one or both eyes, suggesting a global change in circuit excitability that was not restricted to cells that viewed the world through the prematurely opened eye. No major changes were noted in spatial frequency tuning. These results suggest that premature visual experience alters circuit excitability and visual receptive fields, in particular with respect to temporal processing. We speculate that closed lids in altricial mammals serve to prevent visual experience until circuits are initially established and are ready to be refined by visual experience.

Short Polysialic Acid Counteracts Age-Related Synaptic and Cognitive Deficits
Impaired activity of glutamate transporters, elevated concentration of extrasynaptic glutamate and hyperactivity of extrasynaptic GluN2B-containing NMDA receptors are common features in aging and several neurological conditions, including Alzheimer disease (AD). Previous studies revealed that polysialic acid (polySia), a glycan predominantly carried by the neural cell adhesion molecule NCAM, inhibits extrasynaptic NMDA receptors and supports synaptic plasticity in healthy adult brains. Moreover, intranasal delivery of polySia with the degree of polymerization 12 (NANA12) rescued synaptic plasticity and cognitive functions in models of tauopathy and amyloidosis associated with AD. Here, we comparatively studied the effects of NANA12 in young (4 months) old (26 months) and very old (29 months) mice. Strikingly, NANA12 promoted cognitive flexibility in attentional set-shifting (ASST) tests and spatial memory in the Barnes maze in very old mice. To capture fine-grained effects undetectable by conventional methods, we introduced a novel trial-wise data analysis approach for evaluating ASST performance. The observed cognitive improvements were not due to changes in the size of hippocampal memory engrams, visualized by c-Fos immunolabeling after reactivation of spatial memory in the probe trial. Five-day treatment with NANA12 did not affect neuronal structure (MAP2 levels), expression of senescence (lipofuscin) or neuroinflammation (microglial Iba1) markers, activation of BDNF receptors (p-TrkB) or expression of endogenous polySia in the hippocampus of very old mice. However, cognitive improvements correlated with the normalized size of CD68+ microglial lysosomes and reduced amounts of pre- and postsynaptic proteins at these structures. Thus, our data demonstrate the potential of short polySia to reduce synaptic phagocytosis and restore key cognitive functions attenuated in aging.

Optimal positioning and size of high-density electrocorticography grids for speech brain-computer interfaces
Speech-based brain-computer interfaces (BCIs) can offer an intuitive means of communication for those who have lost the ability to speak due to paralysis. Significant progress has been made in classifying individual words from high numbers of electrocorticographic (ECoG) electrodes on the sensorimotor cortex (SMC). As implantations of larger grids with more ECoG electrodes are associated with higher surgical risk, we here examined whether confined electrode configurations can match the classification accuracy of larger grids. To this end, we analyzed data from eight able-bodied participants with high-density ECoG grids (64 to 128 electrodes) who performed a task that involved speaking 12 Dutch words. Word pronunciation was associated with changes in high frequency band activity in two SMC foci, one in the ventral SMC and another in the dorsal SMC. Using a combinatorics approach, we found that a smaller, rectangular, configuration with a surface area of 325 mm2 to 561 mm2 (32 electrodes) could achieve a word classification accuracy similar to that of the larger grids: 76{+/-}16% versus 75{+/-}17% across participants, respectively (practical chance level 16.7%). The best configurations were oriented vertically and centered on the central sulcus. These findings indicate that a 32-electrode ECoG grid placed optimally can be sufficient for achieving high word classification accuracy on a closed set of words. We conclude that targeted placement of small ECoG grids can reduce surgical demands on end users and justify energy- and complexity-efficient designs of fully implantable BCI devices for individuals with severe paralysis.

Tuft dendrites in frontal motor cortex enable flexible learning
Flexible learning relies on integrating sensory and contextual information to adjust behavioral output in different environments. The anterolateral motor cortex (ALM) is a frontal area critical for action selection in rodents. Here we show that inputs critical to decision-making converge on the apical tuft dendrites of L5b pyramidal neurons in ALM. We therefore investigated the role of these dendrites in a rule-switching paradigm. Activation of dendrite-inhibiting layer 1 interneurons impaired relearning, without affecting previously learned behavior. Remarkably, this inhibition profoundly suppressed calcium activity selectively in dendritic shafts but not spines while reducing burst firing. Moreover, excitatory synaptic inputs to tuft dendrites exhibited rule-dependent clustering. We conclude that active dendritic integration is a key computational component of flexible learning.

The Neural Basis of Habit Formation Measured in Goal-Directed Response Switching
To override ongoing habitual responses requires switching well-learned actions with new goal-directed processing. However, the neural circuits responsible for these processes remain unclear. This study infers habit strength by introducing a novel task capturing the increased cost associated with switching a habitual response. We employed neuroimaging and brain stimulation to examine the dynamic interactions between human brain regions involved in habits and their interference with ongoing incompatible goal-directed behavior. Training S-R links in overtrained stimuli (compared to less trained ones, termed standard-trained stimuli) increased RT switch costs, explained by drift diffusion computations governing both the training and outcome devaluation phases. Training engaged sensorimotor areas and the posterior putamen, whereas standard trained behaviors, recruited the posterior caudate, insula, and prefrontal regions. A cortical network orchestrated habit expression (right S1 with the left anterior insula/prefrontal areas) while also implicating basal ganglia when overriding habits (left premotor with the putamen). Importantly, stimulation of the left premotor played a causal role in habit control, enhancing performance across both the training and devaluation phases. Our findings reveal an interaction between habitual and goal-directed brain regions, highlighting shared neural dynamics when overriding habitual behaviors.

Thermal cycling-hyperthermia attenuates rotenone-induced cell injury in SH-SY5Y cells through heat-activated mechanisms
Parkinson's disease (PD) is the second most prevalent neurodegenerative disease. It is characterized by mitochondrial dysfunction, increased reactive oxygen species (ROS), -synuclein (-syn) and phosphorylated-tau protein (p-tau) aggregation, and dopaminergic neuron cell death. Current drug therapies only provide temporary symptomatic relief and fail to stop or reverse disease progression due to the severe side effects or the blood-brain barrier. This study aimed to investigate the neuroprotective effects of thermal cycling-hyperthermia (TC-HT) in an in vitro PD model using rotenone (ROT)-induced human neural SH-SY5Y cells. Our results revealed that TC-HT reduced ROT-induced mitochondrial apoptosis and ROS accumulation in SH-SY5Y cells. TC-HT also inhibited the expression of -syn and p-tau through heat-activated pathways associated with sirtuin 1 (SIRT1) and heat-shock protein 70 (Hsp70), involved in protein chaperoning, and resulted in the phosphorylation of Akt and glycogen synthase kinase-3{beta} (GSK-3{beta}), which inhibit p-tau formation. These findings underscore the potential of TC-HT as an effective treatment for PD, which can be practically implemented via the focused ultrasound (FUS).

Beyond beta: Aperiodic broadband power reflects Parkinson's disease severity - a multicenter study
Parkinson's disease is linked to increased beta oscillations in the subthalamic nucleus, which correlate with motor symptoms. However, findings across studies have varied. Our standardized analysis of multicenter datasets reveals that insufficient sample sizes contributed to these discrepancies - a challenge we address by pooling datasets into one large cohort (n=119). Moving beyond beta power, we disentangled spectral components reflecting distinct neural processes. Combining aperiodic offset, low beta, and low gamma oscillations explained significantly more variance in symptom severity than beta alone. Moreover, interhemispheric within-patient analyses showed that, unlike beta oscillations, aperiodic broadband power - likely reflecting spiking activity - was increased in the more affected hemisphere. These findings identify aperiodic broadband power as a potential biomarker for adaptive deep brain stimulation and provide novel insights into the relationship between subthalamic hyperactivity and motor symptoms in human Parkinson's disease.

Neural oscillation as a selective modulatory mechanism on decision confidence, speed and accuracy
Neural oscillations have been associated with decision-making processes, but their underlying network mechanisms remain unclear. This study investigates how neural oscillations influence decision network models of competing cortical columns with varying intrinsic and emergent timescales. Our findings reveal that decision networks with faster excitatory than inhibitory synapses are more susceptible to oscillatory modulations. Higher in-phase oscillation amplitude reduces decision confidence without affecting accuracy, while decision speed increases. In contrast, anti-phase modulation increases decision accuracy, confidence and speed. Increasing oscillation frequency reverses these effects. Changing oscillatory phase difference gradually modulates decision behaviour, with decision confidence affected nonlinearly. These effects decouple decision accuracy, speed and confidence, challenge standard speed-accuracy trade-off, and can be explained via state-space trajectories' momentum swinging with respect to network steady states and decision uncertainty manifold. Our work provides mechanistic insights into how neurobiological diversity shapes decision-making processes in the presence of ubiquitous neural oscillations.

Intrahippocampal delivery of hyperphosphorylated human tau oligomers induces neurodegeneration in non-transgenic wildtype mice
Hyperphosphorylated tau (p-tau) forms neurofibrillary tangles, a key biomarker for Alzheimer disease and additional neurodegenerative tauopathies. However, neurofibrillary tangles are not sufficient to cause neuronal dysfunction or death. Intrahippocampal injection of tau isolated from AD patients has limited effects on the cognitive functions of non-transgenic mice, despite the recapitulation of pathological tau deposits in the mouse brain. It therefore remains uncertain as to whether all hyperphosphorylated tau is directly responsible for AD neurodegeneration. We examined this issue by injecting recombinant p-tau oligomers to the hippocampus of non-transgenic, wildtype mice and found progressive cognitive deficits that correlate with neuron death spreading from the ipsilateral hippocampus to the cortex. Apomorphine, which retards p-tau aggregation and cytotoxicity in vitro, antagonized p-tau-induced cognitive deficits and neuron death. These results suggest the pathogenic role of p-tau oligomers and a novel AD model facilitating drug development.

Energy inefficiency underpinning brain state dysregulation in individuals with major depressive disorder
Disruptions in brain state dynamics are a hallmark of major depressive disorder (MDD), yet their underlying mechanisms remain unclear. This study, building on network control theory, revealed that decreased state stability and increased state-switching frequency in MDD are driven by elevated energy costs and reduced control stability, indicating energy inefficiency. Key brain regions, including the left dorsolateral prefrontal cortex, exhibited impaired energy regulation capacity, and these region-specific energy patterns were correlated with depressive symptom severity. Neurotransmitter and gene expression association analyses linked these energy deficits to intrinsic biological factors, notably the 5-HT2a receptor and excitatory-inhibitory balance. These findings shed light on the energetic mechanism underlying brain state dysregulation in MDD and its associated biological underpinnings, highlighting brain energy dynamics as a potential biomarker by which to explore therapeutic targets and advance precise interventions for restoring healthy brain dynamics in depression.

Scene segmentation processes drive EEG-DCNN alignment
Visual processing in biological and artificial neural networks has been extensively studied through the lens of object recognition. While deep convolutional neural networks (DCNNs) have demonstrated hierarchical feature extraction similar to biological systems (DiCarlo and Cox, 2007; Yamins and DiCarlo, 2016), recent findings reveal a growing discrepancy: DCNNs with higher object categorization accuracy paradoxically show worse performance at predicting neural responses (Xu and Vaziri-Pashkam, 2021; Linsley et al., 2023). Using a large-scale human electroencephalography (EEG) dataset (n=10, 82,160 trials), we investigate whether this discrepancy arises because human neural EEG signals predominantly reflect scene segmentation processes rather than high-level, category-specific object representations. We trained DCNNs to perform object recognition using visual diets (~1 million training images across 292 object categories) with systematically varying scene segmentation demands: objects-only (pre-segmented), background-silhouette (explicit boundaries), original/background-only images (requiring full segmentation). Despite substantial differences in categorization accuracy (27-53%), all trained models showed remarkably uniform encoding performance, with peak correlations with neural data at ~0.1s post-stimulus. Layer-wise analysis revealed a significant negative correlation between categorization accuracy and encoding performance, with earlier network layers better predicting EEG responses than deeper layers specialized for object categorization. This dissociation suggests that EEG signals primarily reflect fundamental scene parsing mechanisms rather than object-specific representations, explaining the growing discrepancy between DCNNs increasing categorization performance but deteriorating neural prediction performance.

Spatial Transcriptomics of Schizophrenia Insular Cortex Reveals Blood-Brain Barrier Hyperglycolysis and Increased Parenchymal Mitochondrial Respiration
Introduction: The blood-brain barrier (BBB) acts as the metabolic and immunological gatekeeper of the brain. Since alterations in neurometabolism and neuroimmunity are found in schizophrenia-spectrum disorders (SSD) which are hypothesised to be important disease mechanisms, we aimed to investigate whether changes in BBB function could underly these findings using a novel spatially resolved transcriptomics technique. Methods: Formalin-fixed paraffin-embedded insular cortex tissue from 8 brain donors with SSD and 8 matched controls derived from the Netherlands Brain Bank-Psychiatry were selected for whole transcriptome analysis (GeoMx Human Whole Transcriptome Atlas) on the GeoMx Digital Spatial Profiler platform. Combining nuclear staining with an endothelial cell marker (CD31) allowed for the separation of BBB and parenchyma areas of interest (AOIs) for downstream sequencing on the Illumina NextSeq 2000. For each sample, biological triplicates were sequenced. Comparing SSD to control for both the BBB and parenchyma AOIs, differentially expressed genes (DEGs) were identified using a Linear Mixed Model, a heatmap was created displaying all genes with a false-discovery rate <0.01, and Fast Gene Set Enrichment Analysis was used for pathway analysis. Results: A total of 96 whole transcriptome profiles were generated (24 BBB and 24 parenchyma for both SSD and controls). Expression of endothelial genes (PECAM1/CD31, CLDN5, VWF, CD34, ENG) was significantly increased in BBB, confirming enrichment of endothelial cells (ECs) in this AOI. Cluster analysis showed perfect clustering of BBB versus parenchyma, and good clustering of SSD samples within the BBB cluster. At an absolute Log2FC <0.25, we identify 265 significantly DEGs in the BBB AOI and 6 in the parenchyma AOI comparing SSD to control. Pathway analysis revealed a distinct metabolic transcriptional profile in SSD, characterized by hyperglycolysis in the BBB and increased mitochondrial energy metabolism in parenchyma. Conclusion: Our findings implicate the BBB in the metabolic pathophysiology of SSD. Furthermore, our findings add nuance to the existing understanding of brain bioenergetic alterations in SSD, suggesting that metabolic changes may be region-specific rather than generalized. This highlights the need for a brain mapping approach examining multiple brain regions from the same donor. Finally, the distinct metabolic profiles of the BBB and brain parenchyma emphasize the importance of spatial multi-omics in post-mortem psychiatric research and the potential for therapies targeting BBB function in SSD.

Identifying neuropeptides in Hydra: a custom pipeline reveals a non-amidated regulator of muscle contraction and other new members
Neuropeptides play a critical role in neurotransmission and organismal development. Members of phylum Cnidaria, with a diffused nervous system, are one of the earliest divergent animals and might provide insights into the fundamentals of the emergence of neuronal communications. The neuropeptide diversity in Hydra (a cnidarian model) has been extensively studied using various strategies, each with certain limitations. Here, we have developed an in silico pipeline which identified both reported peptides and many new potential candidates. A comparative analysis within Cnidaria suggests a rapid divergence of neuropeptides which might be involved in complex behaviors. We identified new Hydra neuropeptides that belong to the RFamide and PRGamide families and a novel class of peptides lacking amidation (LW-peptides). A detailed expression and functional analysis of a new LW-peptide indicates its role in the longitudinal contraction of Hydra polyps. This study provides compelling evidence for the existence of intricate peptidergic communication in early neuronal circuits. The extensive diversity of neuropeptides within this phylum underscores their rapid evolutionary adaptability. This current pipeline also proves to be simple and adaptable to perform neuropeptide identification in other multicellular organisms.

The Neurocognitive Mechanisms Underlying Narrative Schematic and Paraphrastic Transmission
Narrative transmission serves multiple crucial functions, such as cultural preservation, knowledge accumulation, and consensus building, in human society. However, our understanding of its neurocognitive mechanisms remains limited. In this study, we combined a social transmission chain design with fMRI to investigate the dynamic changes of different narrative components occurring throughout transmission chains and to uncover the factors driving fidelity and distortion. A total of 58 participants were scanned as they listened to and subsequently recalled a story within a social transmission chain. We distinguished two types of transmission modes: schematic transmission, which prioritizes preserving the structural framework of the information, and paraphrastic transmission, which entails rephrasing the content while conveying its meaning. Behavioral results revealed a pattern in which paraphrastic transmission led to distortion and divergence, whereas schematic transmission remained more stable and convergent. Neural findings indicated that the transmission of story structure and content involved subsystems of the Default Mode Network (DMN) and specific subregions of the Hippocampus (HPC). While neural reinstatement between narrative listening and speaking failed to predict across-generation fidelity of content and structure, functional connectivity pattern similarity analysis showed that the DMN and HPC work as an episodic memory system supporting transmission performance. These findings highlight that narrative transmission is supported by distinct neurocognitive representations within episodic memory subsystems, which work collaboratively to sustain the transmission of narratives.

Sub-second Fluctuation between Top-Down and Bottom-Up Modes Distinguishes Diverse Human Brain States
Information continuously flows between regions of the human brain, exhibiting distinct patterns that dynamically shift across states of consciousness, cognitive modes, and neuropsychiatric conditions. In this study, we introduce Relative Phase Analysis (RPA), a method that leverages phase-lead/lag relationships to reveal the real-time dynamics of dominant directional patterns and their rapid transitions. We demonstrate that the human brain switches on a sub-second timescale between a top-down mode--where anterior regions drive posterior activity--and a bottom-up mode, characterized by reverse directionality. These dynamics are most pronounced during full consciousness and gradually become less distinct as awareness diminishes. Furthermore, we find from simultaneous EEG-fMRI recordings that the top-down mode is expressed when higher-order cognitive networks are more active while the bottom-up mode is expressed when sensory systems are more active. Moreover, comparisons of an attention deficit hyperactivity disorder (ADHD) inattentive cohort with typically developing individuals reveal distinct imbalances in these transition dynamics, highlighting the potential of RPA as a diagnostic biomarker. Complementing our empirical findings, a coupled-oscillator model of the structural brain network recapitulates these emergent patterns, suggesting that such directional modes and transitions may arise naturally from inter-regional neural interactions. Altogether, this study provides a framework for understanding whole-brain dynamics in real-time and identifies sub-second fluctuations in top-down versus bottom-up directionality as a fundamental mechanism underlying human information processing.

Constructing the Human Brain Metabolic Connectome Using MR Spectroscopic Imaging: Insights into Biochemical Organization, Cytoarchitectonic Similarity and Gene Co-expression Networks
Network science has revolutionized our understanding of brain organization by revealing self-organizing patterns underlying its structural and functional connectivity. However, capturing metabolic contrast remains a challenge, leaving a critical gap in connectomics. Using advanced 3D whole-brain proton MR spectroscopic imaging with high spatial resolution and shortened acquisition times, we constructed the first human brain metabolic connectome in 51 healthy subjects, validated on an independent cohort (N=12) scanned at a different site. Our pipeline generates consistent and reliable metabolic similarity matrices. Upon further analysis, metabolic similarity networks display distinct topological features, notably a smoothly varying gradient delineating functionally and spatially distinct yet integrated brain regions via connector hubs. Although metabolic hubs correlate with structural hubs, overall alignment with structural connectivity is poor. However, metabolic organization aligns more closely with cytoarchitectonic and genetic co-expression patterns, suggesting a neurodevelopmental origin. This work puts forward the metabolic similarity gradient as a hallmark of the brain's overarching biochemical organization, and provides a foundation for incorporating metabolite imaging into the broader domain of connectomics and its potential applications in health and disease.

Visual and vestibular reweighting after cyber- and space-sickness
Sensory conflicts are widely recognized as the primary drivers of motion sickness (MS), though the underlying integrative processes remain poorly understood. This study investigated sensory reweighting that follows exposure to different sensory conflict paradigms. First, visual and vestibular reflexes were assessed before and after a visuo-vestibular conflict induced by purely visual stimulation in virtual reality. Second, visual and vestibular integration were evaluated before and after an otolith-canal conflict induced by gravitational changes in parabolic flight. Semi-circular canal integration was measured via the vestibulo-ocular reflex (VOR) suppression task, while visual weighting was assessed through optokinetic nystagmus (OKN). Our findings revealed that different sensory conflict paradigms elicit distinct sensory reweighting processes. Visuo-vestibular conflict resulted in a decreased VOR response, whereas vestibulo-vestibular conflict mainly led to a reduction in OKN following parabolic flight. Sensory down-weighting occured in the modality that did not detected displacement, likely perceived as the less reliable input, regardless of its accuracy. Additionally, visual sensitivity emerged as a potential predictor of cybersickness, while vestibular sensitivity seemed to influence MS severity in parabolic flight. Our data suggest that the sensitivity of the most stimulated sensory modality during a given conflict may determine an individual's susceptibility to MS.

Chirp Sensitivity and Vowel Coding in the Inferior Colliculus
The inferior colliculus (IC) is an important brain region to understand neural encoding of complex sounds due to its diverse sound-feature sensitivities, including features that are affected by peripheral nonlinearities. Recent physiological studies in rabbit IC demonstrate that IC neurons are sensitive to chirp direction and velocity. Fast spectrotemporal changes, known as chirps, are contained within pitch-periods of natural vowels. Here, we use a combination of physiological and modeling strategies to assess the impact of chirp-sensitivity on vowel coding. Neural responses to vowel stimuli were recorded and vowel-token identification was evaluated based on average-rate and spike-timing metrics. Response timing was found to result in higher identification accuracy than rate. Additionally, rate bias towards low-velocity chirps, independent of chirp direction, was shown to correlate with higher vowel-identification accuracy based on timing. Also, direction bias in response to chirps of high velocity was shown to correlate with vowel-identification accuracy based on both rate and timing. Responses to natural-vowel tokens of individual neurons were simulated using an IC model with controllable chirp sensitivity. Responses of upward-biased, downward-biased, and non-selective model neurons were generated. Manipulating chirp sensitivity influenced response profiles across natural vowel tokens and vowel discrimination based on model-neuron responses. More work is needed to match all features of model responses to those of physiological recordings.

Spinal processing of spatiotemporally diverse tactile stimuli: Implications for allodynia and spinal cord stimulation
Touch is mistakenly perceived as painful when inhibition in the spinal dorsal horn (SDH) is weakened. Disinhibition un-gates a polysynaptic spinal circuit, but why mechanical allodynia is predominantly evoked by certain stimuli, like dynamic brushing, remains unclear. To answer this, we incorporated receptive fields (RFs) into a computational model of the SDH to study the processing of stimuli with different spatiotemporal features. Broad stimuli normally suppress output spiking by engaging inhibition from the RF surround, but the efficacy of inhibition depends on the input's temporal pattern. This is critical since excitatory and inhibitory spinal neurons are preferentially sensitive to synchronous and asynchronous input, respectively. Furthermore, spikes driven by synchronous input are resistant to feedforward inhibition. The combined results explain why broad dynamic touch (e.g. brush or vibration) evokes more allodynia than punctate static touch. Our results also show that asynchronous and spatially disordered input evoked by kilohertz-frequency spinal cord stimulation preferentially activates inhibitory neurons, thus explaining its anti-allodynic effects.

Inhibitory cell type heterogeneity in a spatially structured mean-field model of V1
Inhibitory interneurons in the cortex are classified into cell types differing in their morphology, electrophysiology, and connectivity. Although it is known that parvalbumin (PV), somatostatin (SST), and vasoactive intestinal polypeptide-expressing neurons (VIP), the major inhibitory neuron subtypes in the cortex, have distinct modulatory effects on excitatory neurons, how heterogeneous spatial connectivity properties relate to network computations is not well understood. Here, we study the implications of heterogeneous inhibitory neurons on the dynamics and computations of spatially-structured neural networks. We develop a mean-field model of the system in order to systematically examine excitation inhibition balance, dynamical stability, and cell-type specific gain modulations. The model incorporates three inhibitory cell types and excitatory neurons with distinct connectivity probabilities and recent evidence of long range spatial projections of SST neurons. Position dependent firing rate predictions are validated against simulations, and balanced solutions under Gaussian assumptions are derived from scaling arguments. Stability analysis shows that while long-range inhibitory projections in E-I circuits with a homogeneous inhibitory population result in instability, the heterogeneous network maintains stability with long-range SST projections. This suggests that a mixture of short and long-range inhibitions may be key to providing diverse computations while maintaining stability. We further find that conductance-based synaptic transmissions are necessary to reproduce experimentally observed cell-type-specific gain modulations of inhibition by PV and SST neurons. The mechanisms underlying cell-type-specific gain changes are elucidated using linear response theory. Our theoretical approach offers insight into the computational function of cell-type-specific and distance-dependent network structure.

The NTU-DSI-122 template as a flexible platform for fiber orientation distribution registration of diffusion microstructure into stereotaxic space
The registration of neuroimaging subjects to a common stereotaxic space allows for comparisons between timepoints, subjects, or with reference atlases of regions of interest. Typically, this has been performed by computing a similarity metric between the voxel-wise intensity values in the subject image and a reference image. Diffusion MRI is a method that provides far more detailed voxel-wise information than a simple scalar intensity value. This allows for the potential to use this additional information to perform registration with added within-tissue contrast. In this study, we present a novel use of the NTU-DSI-122 template as a fiber orientation distribution (FOD) template, for the purpose of registering subject dMRI images to stereotaxic space. The reliability and accuracy of this FOD-based registration method are compared to the intensity-based registration method ANTs by registering cellular microstructure maps from two separate cohorts to the NTU-DSI-122 template. The stochastic FOD-based method significantly outperformed the stochastic intensity-based metric on reliability and was able to more consistently register the same subject multiple times independently. The FOD-based method also significantly outperformed the intensity-based metric on registration accuracy by more completely aligning the microstructure maps to the template as measured by the Sorenson-Dice coefficient at multiple percentile thresholds. The NTU-DSI-122 template has the additional benefit of including multiple b-value shells between a wide range of feasible acquisition schemes, making the platform a flexible option for registering acquisitions of varying quality, including clinically acquired data.

Slow-varying normalization explains diverse temporal frequency masking interactions in the macaque primary visual cortex
Neurons in the primary visual cortex (V1) respond non-linearly with increasing stimulus contrast or with presentation of multiple stimuli, which has been explained by a normalization model where the excitatory drive is divided by the summed activity of a larger neuronal population. However, while recent studies have suggested that normalization could be time and frequency-dependent, neural mechanisms underlying this dependence remain unknown. We presented two overlapping counterphasing grating stimuli (plaids), either parallelly or orthogonally, at multiple contrasts and temporal frequencies and recorded spikes, local field potential and electrocorticogram activity from V1 of bonnet macaques while they passively fixated. The resulting steady-state visually evoked potentials (SSVEPs) exhibited complicated dynamics -- with "low-pass" and "band-pass" suppression profiles for orthogonal and parallel plaids, respectively. Surprisingly, adding a simple low-pass filter in the normalization signal sufficiently explained these diverse effects. Our results present a simple mechanism to explain the spectro-temporal dynamics of normalization.

A robust and comprehensive quality control of cerebral cortical organoids: methodology and validation
Cerebral organoids hold great promise for neuroscience research as complex in vitro models that mimic human brain development. However, they face significant challenges related to quality and reproducibility, leading to unreliability in both academic and industrial contexts. Discrepancies in morphology, size, cellular composition, and cytoarchitectural organization limit their application in biomedical studies, particularly in disease modeling, drug screening, and neurotoxicity testing, where consistent models are essential. Critically, current methods for organoid characterization often lack standardization and rely heavily on subjective assessments, restricting their broader applicability. In this study, we developed a comprehensive Quality Control (QC) framework for 60-days cortical organoids. Five key criteria: morphology, size and growth profile, cellular composition, cytoarchitectural organization, and cytotoxicity, are evaluated using a standardized scoring system. We implemented a hierarchical approach, beginning with non-invasive assessments to exclude low-quality organoids (Initial Scoring), while reserving in-depth analyses for those that passed the initial evaluation (Final Scoring). To validate this framework, we exposed 60-day cortical organoids to graded doses of hydrogen peroxide (H2O2), inducing a spectrum of quality outcomes. The QC system demonstrated its robustness and reproducibility by accurately discriminating organoid quality based on objective and quantifiable metrics. This standardized and user-friendly framework for quality assessment not only minimizes observer bias but also enhances the reliability and comparability of cerebral organoid studies. Additionally, its scalability makes it suitable for industrial applications and adaptable to other organoid types, offering a valuable tool for advancing both fundamental and preclinical research.

Peptidergic top-down control of metabolic state-dependent behavioral decisions in a conflicting sensory context
Animals make economically beneficial behavioral decisions by integrating the external sensory environment with their internal state. The metabolic state, i.e. hunger, can shift priorities, prompting risk-taking and reducing responses to danger during foraging activities. How behavioral changes are processed in the nervous system to generate flexible responses based on needs and risks remains largely unclear. Here, we demonstrate in Drosophila larvae that the corticotropin releasing hormone (CRH) homolog diuretic hormone 44 (Dh44) and its producing neurons exert metabolic top-down control of behavioral choice in a conflicting sensory context. The metabolic state via Dh44 signaling mediates the transition from avoiding to tolerating aversive light conditions in the presence of food. In vivo imaging of neuropeptide release revealed that Dh44 regulates the acute release of Insulin-like peptide 7 (Ilp7) specifically in a conflicting context, thereby inducing light tolerance. Optogenetic activation of specific subsets of Dh44 or Ilp7 producing neurons during starvation is sufficient to shift behavior from light tolerance to avoidance by regulating light avoidance circuit responses. This top-down feedforward peptidergic circuit may represent a general mechanism that helps organisms to balance risk-taking with metabolic needs by allowing flexible adjustment of behavior in a conflicting multisensory environment.

Distinguish risk genes functioning at presynaptic or postsynaptic regions and key connectomes associated with pathological α-synuclein spreading
Previous studies have suggested that pathological -synuclein (-Syn) mainly transmits along the neuronal network, but several key questions remain unanswered: (1) How many and which connections in the connectome are necessary for predicting the progression of pathological -Syn? (2) How to identify risk gene that affects pathology spreading functioning at presynaptic or postsynaptic regions, and are these genes enriched in different cell types? Here, we addressed these key questions with novel mathematical models. Strikingly, the spreading of pathological -Syn is predominantly determined by the key subnetworks composed of only 2% of the strongest connections in the connectome. We further explored the genes that are responsible for the selective vulnerability of different brain regions to transmission to distinguish the genes that play roles in presynaptic from those in postsynaptic regions. Those risk genes were significantly enriched in microglial cells of presynaptic regions and neurons of postsynaptic regions. Gene regulatory network analyses were then conducted to identify 'key drivers' of genes responsible for selective vulnerability and overlapping with Parkinson's disease risk genes. By identifying and discriminating between key gene mediators of transmission operating at presynaptic and postsynaptic regions, our study has demonstrated for the first time that these are functionally distinct processes.

Propofol differentially modulates consolidation of schema-congruent and -incongruent memory
Congruency of newly learned information with previous knowledge (i.e. a mental schema) leads to facilitated encoding and rapid integration into neocortical memory networks. It is less known whether this is associated with a differential involvement of the hippocampus in consolidation of schema-congruent and -incongruent information. Here, we used the GABAA-ergic anesthetic propofol to transiently modulate hippocampal neural activity shortly after encoding of schema-congruent and incongruent information in human patients. We found a significant difference in memory of schema-congruent and incongruent words in patients that was absent in controls. This effect was driven by a benefit for schema-congruent words, thus suggesting that propofol administration facilitated consolidation of previously encoded schema-congruent items. Our results suggest that schema-congruency of newly learned information significantly modulates involvement of hippocampus-dependent networks during memory consolidation. They further support the hypothesis of a competitive interaction between hippocampus and extra-hippocampal networks during early memory consolidation.

A Neural Circuit Framework for Economic Choice: From Building Blocks of Valuation to Compositionality in Multitasking
Value-guided decisions are at the core of reinforcement learning and neuroeconomics, yet the basic computations they require remain poorly understood at the mechanistic level. For instance, how does the brain implement the multiplication of reward magnitude by probability to yield an expected value? Where within a neural circuit is the indifference point for comparing reward types encoded? How do learned values generalize to novel options? Here, we introduce a biologically plausible model that adheres to Dale's law and is trained on five choice tasks, offering potential answers to these questions. The model captures key neurophysiological observations from the orbitofrontal cortex of monkeys and generalizes to novel offer values. Using a single network model to solve diverse tasks, we identified compositional neural representations - quantified via task variance analysis and corroborated by curriculum learning. This work provides testable predictions that probe the neural basis of decision making and its disruption in neuropsychiatric disorders.

Fat taste responsiveness, but not dietary fat intake, is affected in Adipor1 null mice
Taste is a major driving force that influences food choices and dietary intake. Adiponectin has been shown to selectively enhance cellular responses to fatty acids by mediating the activation of AMPK and translocation of CD36 in taste cells via its receptor AdipoR1. Whether Adipor1 gene knockout affects fat taste responsiveness and dietary fat intake in animals remains unclear. In the present study, we evaluated cellular, neural, and behavioral responses to fat, as well as the dietary fat intake in global Adipor1 knockout mice and their WT controls. Sex-specific changes in cellular and behavioral responses to fatty acid were observed in Adipor1 knockout mice. Linoleic acid (LA)-induced calcium responsiveness appears to be reduced in taste cells from Adipor1-deficient males and increased in taste cells from Adipor1-deficient females. Brief-access taste testing revealed a loss of fat taste behavioral responsiveness in naive Adipor1-/- animals. Fat taste loss found in Adipor1-/- males was restored after fat exposure and showed no significant differences in taste behavioral responses to fatty acids with WT controls in two-bottle preference and conditioned taste aversion tests. Adipor1-/- females were found to have diminished preference for LA in two-bottle preference tests, lower intralipid/water lick ratio in a brief-access assay, and reduced avoidance for LA in conditioned taste aversion assay. Furthermore, the taste nerve responses to intralipid and the dietary fat intakes appeared to be the same between Adipor1-/- and WT mice. In the high-fat diet feeding study, Adipor1-/- females gained more weight, while no differences in body weight gain were found in males. Together, we show that adiponectin/AdipoR1 signaling plays crucial sex-specific roles in the modulation of fat taste and the maintenance of healthy body weight primarily by regulating energy expenditure rather than dietary fat intake in mice.

PARylation in Parkinson's disease: a bridge between Lewy body formation and neuronal cell death
Poly-ADP-ribosylation (PARylation), catalyzed by the enzyme PARP1, involves the addition of poly-ADP-ribose polymers (PAR) and has been associated with -synuclein aggregation in Parkinson's disease (PD) models. This study aimed to unravel the role of PARylation in -synuclein aggregation and neuronal cell death in the complex environment of post-mortem human PD brains. Using high-resolution imaging and 3D reconstruction analysis, we observed that PAR accumulate in the cytoplasm in regions affected by PD pathology, preceding the formation of -synuclein oligomers. Additionally, we found that PAR and stress granules contribute to the formation of Lewy bodies. Increased colocalization of PAR with mitochondria in the substantia nigra of PD patients, along with the presence of PAR-positive condensed DNA, further suggests a role in neuronal cell death. Collectively, our findings reveal a critical involvement of PARylation in the pathological mechanisms underlying neurodegeneration in PD and position PARylation as a potential therapeutic target.

Spatial flexibility of distractor suppression in the tactile modality
Object sensing and manipulation rely on the somatosensory system's ability to relay relevant information about a skin location encoding tactile information about the object while suppressing irrelevant or distracting inputs on the skin, a process known as distractor suppression. Although tactile selective attention is flexible, capable of being allocated to non-contiguous skin areas on the hand and with spatial resolution limited to within a finger, the spatial properties of distractor suppression in touch remain poorly understood. In particular, studies have not explored the effects of proactively cueing distractor locations in touch, leaving open questions about whether active deployment of distractor suppression operates independently of attentional enhancement. To address this gap in knowledge, in this study, participants performed an amplitude discrimination task on the hand in the presence of distractors that were cued in advance. Our data revealed that validly cueing distractor locations improves discrimination accuracy and reduces reaction times of behaviorally relevant tactile stimuli. The data also showed that behavior is unaffected when attended stimuli are flanked by distractors within or across fingers, suggesting that distractor suppression mechanisms can be split across different skin locations on the hand. These findings provide novel insights into the spatial allocation and flexibility of distractor suppression mechanisms in touch, and underscore the importance of proactive cueing in shaping these mechanisms.

Autism risk genes converge on PBX1 to govern neural cell growth
The alteration of neural progenitor cell (NPC) proliferation underlies autism spectrum disorders (ASD). It remains unclear whether targeting convergent downstream targets among mutations from different genes and individuals can rescue this alteration. We identified PBX1 as a convergent target of three autism risk genes: CTNNB1, PTEN, and DVL3, using isogenic iPSC-derived 2D NPCs. Overexpression of the PBX1a isoform effectively rescued increased NPC proliferation in all three isogenic ASD-related variants. Dysregulation of PBX1 in NPCs was further confirmed in publicly available datasets from other models of ASD. These findings spotlight PBX1, known to play important roles during olfactory bulb/adult neurogenesis and in multiple cancers, as an unexpected and key downstream target, influencing NPC proliferation in ASD and neurodevelopmental syndromes.

Androgen receptors expressed in the primary sensory neurons regulate mechanical pain sensitivity
The expression of hormonal receptors in pain-processing regions complicates understanding the hormonal effects on pain mechanisms. This study investigates androgen receptor (AR) involvement in pain sensitivity and sex differences in pain perception. Mechanical pain thresholds were higher in normal male mice compared to gonadectomized (GDX) male and normal female mice, correlating with serum testosterone levels. In the dorsal root ganglia (DRG), AR was expressed in normal males but undetectable in GDX males and normal females. In male sensory neuron-selective AR conditional knockout (AR-cKO) mice, mechanical pain thresholds were significantly lower than in wild-type males. In female mice, administration of testosterone propionate or dihydrotestosterone significantly raised mechanical pain thresholds, accompanied by increased AR expression in the DRG. This effect was abolished in AR-cKO females, consistent with male findings. These results indicate that primary sensory neurons are critical targets of androgen signaling in regulating mechanical pain sensitivity.

AAV-mediated ARSA replacement for the treatment of Metachromatic Leukodystrophy
Metachromatic leukodystrophy (MLD) is an autosomal recessive neurodegenerative disorder caused by mutations in the arylsulfatase A (ARSA) gene, resulting in lower sulfatase activity and the toxic accumulation of sulfatides in the central and peripheral nervous system. Children account for 70% of cases and become progressively disabled with death occurring within 10 years of disease onset. Gene therapy approaches to restore ARSA expression via adeno-associated viral vectors (AAV) have been promising but hampered by limited brain biodistribution. We report the development of a novel capsid AAV.GMU01, demonstrating superior biodistribution and transgene expression in the central nervous system of non-human primates (NHPs). Next, we show that AAV.GMU01-ARSA treated MLD mice exhibit persistent, normal levels of sulfatase activity and a concomitant reduction in toxic sulfatides. Treated mice also show a reduction in MLD-associated pathology and auditory dysfunction. Lastly, we demonstrate that treatment with AAV.GMU01-ARSA in NHPs is well-tolerated and results in potentially therapeutic ARSA expression in the brain. In summary, we propose AAV.GMU01-ARSA mediated gene replacement as a clinically viable approach to achieve broad and therapeutic levels of ARSA.

Synthetic torpor in the rat recapitulates key deatures of torpor and protects the heart from ischaemia-reperfusion injury
During hibernation, animals enter torpor, a reversible physiological state typically characterised by reductions in core temperature, heart rate and oxygen consumption. Species that enter this hypothermic and hypometabolic state are highly tolerant of ischaemia-reperfusion injury. Consequently, there is a growing interest in utilizing aspects of torpor for clinical applications, such as protection from ischaemia-reperfusion injury during stroke or myocardial infarction. It is currently unknown, however, if a torpor-like state is protective in animals that do not naturally enter torpor. Using viral-vector mediated chemogenetics in the medial preoptic area of the hypothalamus, we induced synthetic torpor in the rat, a species that does not naturally enter torpor. We demonstrate this state is cardioprotective in an ex-vivo ischaemia-reperfusion injury model. Synthetic torpor induced cardioprotection of the normothermic, isolated heart is not dependent on hypothermia during synthetic torpor. These findings provide important insights into synthetic torpor states in novel species, and demonstrate feasibility for future clinical translation in humans.

Generation and Characterization of Col6a1 knock-in mice: A Promising Pre-Clinical Model for Collagen VI-Related Dystrophies
Collagen VI Related Dystrophies (COL6-RD) are congenital muscle diseases, typically inherited as an autosomal dominant trait. A frequent type of mutation involves glycine substitutions in the triple helical domain of collagen VI alpha chains, exerting a dominant-negative effect on the unaltered protein. Despite this, no prior animal model captured this mutation type. Using CRISPR/Cas9, we generated transgenic mice with the equivalent of the human COL6A1 c.877 G>A; p. Gly293Arg mutation. We characterized their skeletal muscle phenotype over time, utilizing computer-aided tools applied to standardized parameters of muscle pathology and function. Knock-in mice exhibited early-onset reduced muscle weight, myopathic histology, increased fibrosis, reduced collagen VI expression, muscle weakness, and impaired respiratory function. These features provide adequate outcome measures to assess therapeutic interventions. The different automated image analysis methods deployed here analyze thousands of features simultaneously, enhancing accuracy in describing muscle disease models. Overall, the Col6a1 Ki Gly292Arg mouse model offers a robust platform to deepen our understanding of COL6-RD and advance its therapeutic landscape

Dopamine and calcium dynamics in the nucleus accumbens core during food seeking
Extinction-reinstatement paradigms have been used to study reward seeking for both food and drug rewards. The nucleus accumbens is of particular interest in reinstatement due to its ability to energize motivated behavior. Indeed, previous work has demonstrated that suppression of neuronal activity or dopaminergic signaling in the nucleus accumbens reduces reinstatement to food seeking. In this study, we sought to further establish a connection between glutamatergic input, measured by proxy via a genetically encoded calcium indicator, and dopamine (DA) tone, measured simultaneously with a red-shifted DA biosensor. We performed this sensor multiplexing in the nucleus accumbens core in the classic extinction-reinstatement paradigm with food reward. We detected DA transients that changed in magnitude and/or temporally shifted over the course of self-administration training. In our calcium traces we observed a decrease from baseline time-locked to the lever press for food reward, which became more prominent with training. Both patterns were reduced in the first session of extinction with no deflections from baseline detected in either the DA or calcium traces in the last extinction session. When we recorded during reinstatement tests, bootstrapping analysis detected a calcium response when reinstatement was primed by cue or pellet+cue presentation, while a DA response was detected for pellet+cue reinstatement. These data further establish a role for nucleus accumbens core activity and DA in reinstatement of food seeking and represent the first attempt to simultaneously record the two during an extinction-reinstatement task.

Accurate spatiotemporal retinal responses require a color intensity balance fine-tuned to natural conditions
Color vision is vital for animal survival, essential for foraging and predator detection. In mice, as in other mammals, color vision originates in the retina, where photoreceptor signals are processed by neural circuits. However, retinal responses to stimuli involving multiple colors are still not well understood. One possible explanation of this knowledge gap is that previous studies have not thoroughly examined how neuronal activity adapts to a 30 seconds to a few minutes timescale when exposed to multiple color sources. To address this, we systematically varied the UV-to-green light balance with a custom-built stimulator targeting mice opsins spectra while recording retinal ganglion cell responses in the ventral retina using multielectrode arrays. Responses to full-field chirp and checkerboard stimulations with alternating UV and green light revealed that more than one order of magnitude of intensity difference favoring green M-opsin over UV S-opsin is needed for a balanced reliability in retinal ganglion cell responses. An incorrect balance, with slightly increased UV light, silenced responses to green illumination. To determine if these values are consistent with natural conditions, we analyzed isomerisation rates in the mouse retina across different times of the day. We found that the M- to S-opsin activation ratio remains constant through the mesopic-photopic range, and our empirically determined values align well with these natural conditions, lying far from a simple equalization of M- and S-opsin isomerisation rates. In conclusion, a finely tuned color intensity balance is essential for accurately measuring both fast temporal responses and detailed spatial receptive fields.

MicroRNAs alteration and unique distribution in the soma and synapses of substantia nigra in Parkinsons disease
Parkinsons disease (PD) is the second most common neurodegenerative condition after Alzheimer's. Abnormal accumulation of alpha-synuclein (-syn) aggregates disrupts the balance of dopaminergic (DA-ergic) synapse components, interfering with dopamine transmission and leading to synaptic dysfunction and neuronal loss in PD. However exact molecular mechanism underlying DA-ergic neuronal cell loss in the SNpc in not known. MicroRNAs (miRNAs) are observed in various compartments of neural elements including cell bodies, nerve terminals, mitochondria, synaptic vesicles and synaptosomes. However, miRNAs expression and cellular distribution are unknown in the soma and synapse compartment in PD and healthy state. To address this void of information, we isolated synaptosomes and cytosolic fractions (soma) from post-mortem brains of PD-affected individuals and unaffected controls (UC) and processed for miRNA sequencing analysis. A group of miRNAs were significantly altered (p < 0.05) with high fold changes (variance +/- > 2-fold) in their expressions in different comparisons: 1. UC synaptosome vs UC cytosol, 2. PD synaptosome vs PD cytosol, 3. PD synaptosome vs UC synaptosome, 4. PD cytosol vs UC cytosol. Our study unveiled some potential miRNAs in PD and their alteration and unique distribution in the soma and synapses of SNpc in PD and controls. Further, gene ontology enrichment analysis showed the involvement of deregulated miRNAs in several molecular function and cellular components: synapse assembly formation, cell junction organization, cell projections, mitochondria, Calcium ion binding and protein binding activities.

In-vivo optogenetic manipulation approach for gerbil medial nucleus of trapezoid body
Purpose: This study introduces an in-vivo optogenetic manipulation approach for the medial nucleus of the trapezoid body (MNTB) in Mongolian gerbils, a species with a hearing range similar to humans. The MNTB is crucial for sound localization, but traditional methods lack temporal precision and reversibility. The aim of this study is to develop a specific, reversible method for controlling MNTB activity with fast and precise temporal control, an approach vital for studying sound localization. Methods: We stereotactically injected adeno-associated viral vectors encoding opsins into the gerbil MNTB. Precise targeting was achieved despite the MNTB's location in a deep, heavily myelinated area of the brainstem. Opsin expression was confirmed via confocal microscopy. In-vivo electrophysiology combined with optical stimulation was used to test optical activation and suppression of MNTB activity during sound stimuli. Results: Opsin expression was strong and stable in MNTB neurons over weeks and months. Laser stimulation during in-vivo recordings successfully induced both activation and suppression of MNTB neurons, demonstrating fast and precise control over neural activity. Conclusion: This in-vivo optogenetic method provides specific, reversible control of MNTB activity in gerbils with rapid, real-time modulation. It offers a powerful tool for investigating sound localization and auditory processing with high temporal precision.

The encoding of interoceptive-based predictions by the paraventricular nucleus of the thalamus D2+ neurons
Understanding how the brain integrates internal physiological states with external sensory cues to guide behavior is a fundamental question in neuroscience. This process relies on interoceptive predictions which are internal models that anticipate changes in physiological state based on sensory inputs and prior experiences. Despite recent advances in identifying the neural substrates of interoceptive predictions, the precise neuronal circuits involved remain elusive. In our study, we demonstrate that Dopamine 2 Receptor (D2+) expressing neurons in the paraventricular nucleus of the thalamus (PVT) play key roles in interoception and interoceptive predictions. Specifically, these neurons are engaged in behaviors leading to physiologically relevant outcomes, with their activity highly dependent on the interoceptive state of the mice and the expected outcome. Furthermore, we show that chronic inhibition of PVTD2+ neurons impairs the long-term performance of interoceptive-guided motivated behavior. Collectively, our findings provide insights into the role of PVTD2+ neurons in learning and updating state-dependent predictions, by integrating past experiences with current physiological conditions to optimize goal-directed behavior.

Human insula neurons respond to simple sounds during passive listening
The insula is critical for integrating sensory information from the body with that arising from the environment. Although previous studies suggest that posterior insula is sensitive to sounds, auditory response properties of insula neurons have not previously been reported. Here, we provide the first report of a population of human single neuron data from the insula and provide comparative data from the primary auditory cortex, recorded intracranially from human participants during passive listening. In each condition, more than 330 single neurons were recorded in 11 participants. Almost a third of neurons in posterior insula and a smaller subset in anterior insula responded to simple tones and clicks. Responsive neurons were distributed throughout posterior and anterior insula and showed preferred frequency tuning. Onset latencies in the insula were similar to those in the primary auditory cortex but response durations were significantly shorter. Overall, these data highlight that insula neurons respond to auditory stimuli even in non-behaviorally relevant contexts and suggest an important contribution of audition to the postulated integrative functions of insular cortex.

Modulation of autism-associated serotonin transporters by palmitoylation: Insights into the molecular pathogenesis and targeted therapies for autism spectrum disorder
Background: Autism spectrum disorder (ASD) is a developmental disorder of the nervous system characterized by a deficiency in interpersonal communication skills, a pathologic tendency for repetitive behaviors, and highly restrictive interests. The spectrum is a gradient-based construct used to categorize the widely varying degrees of ASD phenotypes, and has been linked to a genetic etiology in 25% of cases. Prior studies have revealed that 30% of ASD patients exhibit hyperserotonemia, or elevated whole blood serotonin, implicating the serotonergic system in the pathogenesis of ASD. Likewise, escitalopram, a selective-serotonin reuptake inhibitor (SSRI), has been demonstrated to improve aberrant behavior and irritability in ASD patients, potentially by modulating abnormal brain activation. Prior studies have uncovered proband patients with rare mutations in the human serotonin transporter (hSERT) that manifest enhanced surface expression and transport capacity, suggesting that abnormal enhancement of hSERT function may be involved in the pathogenesis of ASD. Methods: HEK-293 cells stably expressing WT, C109A, I425L, F465L, L550V, or K605N hSERT were subject to analysis for palmitoylation via Acyl-Biotin Exchange followed with hSERT immunoblotting. F465L functional enhancement was confirmed by surface analysis via biotinylation and saturation analysis via 5HT transport. F465L palmitoylation, surface expression and transport capacity were then assessed following treatment with 2-bromopalmitate or escitalopram. Results: Here, we reveal that palmitoylation is enhanced in the ASD hSERT F465L and L550V coding variants, and confirm prior reports of enhanced kinetic activity and surface expression of F465L. Subsequently, treatment of F465L with the irreversible palmitoyl acyl-transferase inhibitor, 2-bromopalmitate (2BP), or escitalopram, rectified enhanced F465L palmitoylation, surface expression, and transport capacity to basal WT levels. Limitations: Tests assessing L550V for surface expression, transport capacity, and reactivity to inhibition of palmitoylation was not assessed. In addition, further characterization is necessary for internalization rates, degradative mechanisms, the impact of cysteine-mediated substitutions, and other SSRIs on these processes. Conclusions: Overall, our results implicate disordered hSERT palmitoylation in the pathogenesis of serotonergic ASD subtypes, with basal recovery of these processes following escitalopram providing insight into its molecular utility as an ASD therapeutic.

Motion-corrected eye tracking (MoCET) improves gaze accuracy during visual fMRI experiments
Human eye movements are essential for understanding cognition, yet achieving high-precision eye tracking in fMRI remains challenging. Even slight head shifts from the initial calibration position can introduce drift in eye tracking data, leading to substantial gaze inaccuracies. To address this, we introduce Motion-Corrected Eye Tracking (MoCET), a novel approach that corrects drift using head motion parameters derived from the preprocessing of fMRI data. MoCET requires no additional hardware and can be applied retrospectively to existing datasets. We show that it outperforms traditional detrending methods with respect to accuracy of gaze estimation and offers higher spatial and temporal precision compared to MR-based eye tracking approaches. By overcoming a key limitation in integrating eye tracking with fMRI, MoCET facilitates investigations of naturalistic vision and cognition in fMRI research.

Anle138b ameliorates pathological phenotypes in mouse and cellular models of Huntington's disease
Huntington's disease (HD) is a debilitating hereditary movement disorder caused by a CAG repeat expansion in the huntingtin gene. HD is characterized by deposition of mutant huntingtin (mHTT) aggregates, and by severe neurodegeneration of the basal ganglia and neocortex. No cure is currently available, and new treatment options are urgently needed. Here, we show that the oligomer modifying molecule anle138b (INN: emrusolmin) improves multiple disease phenotypes in cell culture and in two mouse models of HD. Application of anle138b reduced mHTT aggregate formation and ameliorated neurotoxicity in primary neurons. Oral administration of anle138b delayed deposition of mHTT inclusions, reduced brain atrophy, mitigated neuroinflammation, improved motor function and extended life span in HD mice. Downregulation of striatal markers and synapse loss in striatal spiny projection neurons were also partially rescued. No adverse effects of anle138b were observed in wildtype animals. Moreover, anle138b markedly decreased mHTT aggregation in human neural precursor cells differentiated from HD patient-derived induced pluripotent stem cells (iPSCs). Altogether these results illustrate the potential of anle138b as a disease-modifying treatment for HD.

Single-dose rapamycin increases brain glucose metabolism but reduces synaptic density in Long-Evans rats: A PET imaging study
Rapamycin, an inhibitor of the mechanistic target of rapamycin (mTOR), has shown promise as a neuroprotective compound in preclinical studies. Reduced brain glucose metabolism and loss of synaptic density are key features of Alzheimer's disease that can be measured in vivo using positron emission tomography (PET) imaging, allowing for assessment of treatment effects on brain function. Here, we used PET to investigate the acute effects of a single-dose of rapamycin on glucose metabolism and synaptic density in Long-Evans rats. In a repeated measures design, we quantified changes in brain glucose metabolism using [18F]FDG PET (n=13) at baseline, one day, and one week after intraperitoneal administration of rapamycin (8 mg/kg). In a separate cohort (n=6), we measured synaptic density using [18F]SynVesT-1 PET at baseline and one day after rapamycin administration. Regional standardized uptake values (SUV) were calculated for [18F]FDG while total distribution volumes were estimated for [18F]SynVesT-1 using image-derived input functions of the heart. Rapamycin induced significant increases in [18F]FDG SUV across multiple brain regions one day after administration, an effect that persisted at one-week follow-up. In contrast, [18F]SynVesT-1 binding showed significant decreases throughout the brain at 24 hours post-administration, indicating reduced synaptic density. These opposing effects on glucose metabolism and synaptic density point to multifaceted actions of rapamycin in the brain, possibly reflecting improved metabolic function occurring simultaneously with acute synaptic loss. These results show that [18F]FDG and synaptic density PET imaging could serve as useful biomarkers in human clinical trials evaluating rapamycin's mechanistic and therapeutic effects in neurodegenerative disorders.

Spontaneous eye movements reveal that premotor cortex is involved in human thinking
Non-visual saccades (NVS) are spontaneous eye movements humans make while thinking. Their role is puzzling and there is no framework to explain them in terms of their underlying neural systems. Here we studied neural activity preceding NVS when subjects performed standardized abstract thinking tasks. We used high-density EEG and focused on frontal and parietal channels representing oculomotor cortical areas. We found that NVS are preceded by neural activity changes in frontal and parietal EEG channels qualitatively different to that for voluntary saccades. However, only the rate of signal change in frontal channels, but not in parietal channels, surpassed that observed when comparing NVS to normal saccades. Frequency spectrum analyses showed activity patterns reflecting complex top-down and bottom-up processing. A source reconstruction analysis additionally revealed that presaccadic signals originated mainly in the premotor cortex. We propose that this presaccadic activity while thinking represents evidence accumulation and attentional shifts, as shown before in the premotor cortex during sensorimotor tasks. Our findings suggest that human thinking appears to function similarly to human actions and employs premotor areas responsible for evaluating and manipulating objects also when evaluating and manipulating concepts.

The absent P3a. Performance monitoring ERPs differentiate trust in humans and autonomous systems.
To address suggestions that human brain responses to autonomous system errors may be used as brain-based measures of trust in automation, the present study asked participants to monitor the performance of either a virtual human or an autonomous system partner performing a novel, complex, real-world image classification task. We predicted visual feedback of partner errors would elicit the feedback-related negativity and P3 ERP components, and that these components would differ between the human and system groups. Behavioral results showed that while participants calibrated their trust in their partner according to our intended manipulation of error rates, no group differences were found. The ERP data, however, revealed FRN and P3 effects for both groups, modulated by accuracy and error rate. An unexpected finding was that the P3 topography differed between groups, as while the P3 for the human group was widespread, the P3 for the system group was limited to posterior electrodes with the P3a being completely absent. These results demonstrate the potential for EEG-based measures of real-time trust in automation to be used in applied scenarios with benefits beyond traditional methods. Further, we found that a distinct neural processing of autonomous system errors compared to human errors may exist, necessitating further research in this emerging field.

Human pulvinar stimulation engages select cortical pathways in epilepsy
The pulvinar has been proposed as an effective neuromodulation target for patients with posterior quadrant and temporal epilepsies. However, the pulvinar has a large tissue volume, multiple subnuclei, and widespread cortical connections. It remains unknown whether electrical stimulation of distinct pulvinar subregions affects the temporal, occipital, and parietal areas differently. To address this gap, we delivered single-pulse electrical stimulation to the pulvinar and measured the resulting brain stimulation evoked potentials in twelve patients undergoing stereotactic EEG for drug-resistant epilepsy. Brain stimulation evoked potentials were parameterized across the occipital, temporal and parietal cortex. Stimulation of the lateral pulvinar elicited significant brain stimulation evoked potentials in striate and extrastriate areas that diminish as stimulation shifts towards the medial pulvinar. Conversely, stimulation of the ventral aspect of the medial pulvinar produced significant lateral temporal evoked potentials, which diminish with lateral pulvinar stimulation. We also found that stimulation of the dorsomedial pulvinar evoked significant parietal responses with limited striate/extrastriate and lateral temporal responses. These results demonstrate that electrical stimulation of specific pulvinar subregions influences distinct occipital, parietal and lateral temporal areas. Selective targeting of pulvinar subregions to maximize seizure network engagement may be essential for individualized treatment of posterior quadrant and temporal epilepsies.

Acute supplementation of beta-hydroxybutyrate increases visual cortical excitability in humans: a combined EEG and MRS study
Increasing plasma levels of ketone bodies via supplementation or dieting has been repeatedly used to ameliorate neurological symptoms and enhance cognitive performance. Here we aim to gain insight into the underlying mechanisms by characterizing the acute effects on visual cortical function of a single dose B-hydroxybutyrate (BHB) supplementation. Young human volunteers were orally administered a BHB ester; we used EEG to assess cortical excitability and responsivity to visual stimulation, and Magnetic Resonance Spectroscopy to quantify glutamate and GABA+ concentrations in the occipital cortex. BHB supplementation increased the amplitude of Visual Evoked Potentials and enhanced the resting-state EEG alpha rhythm. These electrophysiological changes were paralleled by a neurometabolic change in the occipital cortex, where glutamate (but not GABA+) concentration increased. The glutamate increase was correlated with the increased Visual Evoked Potential amplitude. This suggests that acute BHB supplementation increases the excitability of the brain cortex, as assessed neurometabolically and electrophysiologically.

Effects of complex whole-body movements on EEG activity: a scoping review
The influence of movements on brain activity has been part of research for decades. Recent advancements in electroencephalography (EEG) coupled with a shift in focus towards the effects of complex whole-body movements provided additional inspirations in this area. Besides the metabolic load, the amount of information to be processed in parallel provides rough indications of its influence on central nervous activity. Accordingly, this scoping review aimed to synthesize studies investigating the acute effects of complex whole-body movements with increased parallel information processing on electrical brain activity. A comprehensive search across five scientific databases resulted in thirteen studies meeting the inclusion criteria. The results showed increased theta and alpha activity in frontal, central and parietal areas in most studies during and after movement. However, in other frequency bands the findings were not consistent. Comparisons between complex movements with varying parallel demands revealed a trend towards higher theta for movements with more parallel actions. Based on a consistent EEG methodology, future research should consider movement complexity not only related to the length of sequences but rather in terms of parallel motor activities as a moderator of brain activity to obtain more consistent results in the context of neural effects of movement exercise.

A unique serum-free murine cortical astrocyte culture to study endoplasmic reticulum stress in response to amyloid-β
Astrocytes are integral to understand Alzheimer's disease (AD) pathology but the existing serum-supplemented in vitro astrocyte culture models are not suitable to study certain stress response mechanisms. Here, we developed a serum-free murine primary cortical astrocyte culture model to study endoplasmic reticulum (ER) stress and inflammation to see the effect of amyloid-beta (A{beta}1-42). Astrocytes were cultured in a controlled serum-free environment to minimize interference from serum components. Serum-free astrocytes were exposed to oligomeric A{beta} to induce ER stress and inflammation. Initially no significant activation of eIF2, a key marker of ER stress, was observed under serum-free condition but with the removal of N-acetyl cysteine ER stress response was enhanced after 24 hours of A{beta} exposure. Subsequently, the inflammatory response, assessed through TNF- expression, was minimal in the presence of growth factors but became pronounced when these factors were withdrawn. Astrocytic reactivity, assessed by GFAP expression, was observed with prolonged A{beta} exposure, indicating a reactive astrogliosis response. Transcript analysis revealed a time-dependent shift in the expression of inflammatory modulators, with early time points showing increased anti-inflammatory markers and late exposure promoting pro-inflammatory responses. These findings highlight the potential of serum-free cultures for studying ER stress and inflammation together in astrocytes and offer insights into the complex role of these cells in AD pathophysiology.

A Brain-Computer Interface for Improving Auditory Attention in Multi-Talker Environments
There is significant research in accurately determining the focus of a listener's attention in a multi-talker environment using auditory attention decoding (AAD) algorithms. These algorithms rely on neural signals to identify the intended speaker, assuming that these signals consistently reflect the listener's focus. However, some listeners struggle with this competing talkers task, leading to suboptimal tracking of the desired speaker due to potential interference from distractors. The goal of this study was to enhance a listener's attention to the target speaker in real time and investigate the underlying neural bases of this improvement. This paper describes a closed-loop neurofeedback system that decodes the auditory attention of the listener in real time, utilizing data from a non-invasive, wet electroencephalography (EEG) brain-computer interface (BCI). Fluctuations in the listener's real-time attention decoding accuracy was used to provide acoustic feedback. As accuracy improved, the ignored talker in the two-talker listening scenario was attenuated; making the desired talker easier to attend to due to the improved attended talker signal-to-noise ratio (SNR). A one-hour session was divided into a 10-minute decoder training phase, with the rest of the session allocated to observing changes in neural decoding. In this study, we found evidence of suppression of (i.e., reduction in) neural tracking of the unattended talker when comparing the first and second half of the neurofeedback session (p = 0.012). We did not find a statistically significant increase in the neural tracking of the attended talker. These results establish a single session performance benchmark for a time-invariant, non-adaptive attended talker linear decoder utilized to extract attention from a listener integrated within a closed-loop neurofeedback system. This research lays the engineering and scientific foundation for prospective multi-session clinical trials of an auditory attention training paradigm.

How sleeping minds decide: state-specific reconfigurations of lexical decision-making
Decision-making is a core cognitive function that enables adaptive behavior across diverse contexts. While extensively studied in wakefulness, its persistence and reconfiguration across sleep states remain poorly understood. Here, we use computational modeling to examine lexical decision-making across wakefulness, N1 sleep, and lucid REM sleep in both healthy participants (HP) and participants with narcolepsy (NP). Using facial electromyography (EMG) to capture real-time behavioral responses to spoken words and pseudowords, we quantify how decision-making strategies adapt under different sleep and consciousness states. Our findings reveal two key insights. First, decision-making mechanisms are dynamically reconfigured across sleep states. In N1 sleep, the advantage for word (vs. pseudoword) judgments is supported by faster sensory encoding and motor preparation, combined with efficient evidence accumulation. In contrast, in lucid REM sleep, the word advantage is driven exclusively by enhanced evidence accumulation, while sensory encoding and motor preparation remain unchanged. Second, cross-state comparisons reveal distinct patterns of preservation and impairment. In N1 sleep, word processing remains largely intact, whereas pseudoword processing is significantly impaired, characterized by prolonged stimulus encoding, delayed motor preparation, and reduced evidence accumulation. In contrast, lucid REM sleep is marked by a global reduction in processing efficiency, reflected in slower evidence accumulation and elevated decision thresholds for both words and pseudowords. These results demonstrate that rather than being uniformly degraded, decision-making is dynamically reconfigured across sleep stages, reflecting adaptive neurocognitive strategies that sustain cognition in altered states of consciousness. By identifying state-specific computational mechanisms, this study provides new insights into the brain's resilience and flexibility under changing cognitive and physiological conditions.

SORDINO for Silent, Sensitive, Specific, and Artifact-Resisting fMRI in awake behaving mice
Blood-oxygenation-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) has revolutionized our understanding of the brain activity landscape, bridging circuit neuroscience in animal models with noninvasive brain mapping in humans. This immensely utilized technique, however, faces challenges such as acoustic noise, electromagnetic interference, motion artifacts, magnetic-field inhomogeneity, and limitations in sensitivity and specificity. Here, we introduce Steady-state On-the-Ramp Detection of INduction-decay with Oversampling (SORDINO), a transformative fMRI technique that addresses these challenges by maintaining a constant total gradient amplitude while acquiring data during continuously changing gradient direction. When benchmarked against conventional fMRI on a 9.4T system, SORDINO is silent, sensitive, specific, and resistant to motion and susceptibility artifacts. SORDINO offers superior compatibility with multimodal experiments and carries novel contrast mechanisms distinct from BOLD. It also enables brain-wide activity and connectivity mapping in awake, behaving mice, overcoming stress- and motion-related confounds that are among the most challenging barriers in current animal fMRI studies.

Subliminal risk influences subjective value in the ventromedial prefrontal cortex
The relationship between conscious awareness and decisions has been heavily debated. Here we investigated whether subliminal probabilities are integrated with conscious rewards to form subjective value (SV) representations in the anterior ventral striatum (aVS) and ventromedial prefrontal cortex (vmPFC). Participants played an incentivized competitive game with risky choice to accumulate points across trials in a behavioral and fMRI experiment. The game was a modified attentional-blink paradigm that rendered a probability cue unseen (indicating a 100% or 0% chance to win a risky reward). Following the probability cue, participants chose between a safe (1 point with certainty) or risky option (>1 or 0 points depending on probability cue). The risky reward was either 2 or 5 points, varying across trials. In some trials the probability cue was absent (replaced by a random distractor) and the probability to win the risky reward was 50%. When probability cues were unseen, they did not influence choice, as value-maximizing choice (d-prime) was not greater than chance, but they did influence reaction time in both experiments. Consistent with SV integration, the BOLD signal in aVS and vmPFC was higher for both conscious rewards (high > low) and subliminal probabilities (high > low) and could not be explained by subliminal salience (cue present > absent). Moreover, multivariate pattern similarity between conscious rewards and subliminal probabilities in vmPFC suggest integration into an abstract value representation. Additionally, we found brain-wide subliminal probability and salience effects. Taken together, these results suggest that conscious awareness is not necessary for probability to be integrated with conscious rewards to form an abstract common currency SV representation in vmPFC. Additionally, brain-wide subliminal probability and salience effects suggests information can have global access without conscious awareness.

Amino acids activate parallel chemosensory pathways in Drosophila
Amino acids (AAs) are essential dietary macronutrients that impact an organism's fitness in a concentration-dependent manner, but the mechanisms mediating AA detection to drive consumption are less clear. In Drosophila, we identified the full repertoire of taste cells and receptors involved in feeding initiation towards a glutamate-rich AA mixture, tryptone, using in vivo calcium imaging and the proboscis extension response (PER). We found that AA attraction occurs through sweet cells, whereas feeding aversion is mediated through Ionotropic Receptor 94e (IR94e) cells and bitter cells, dependent on concentration. Further, our results corroborate previous findings that ionotropic receptors IR76b, IR51b, and IR94e detect AAs in their respective cell types. Additionally, we describe a new role for the appetitive IR56d receptor and bitter gustatory receptors in detecting AAs. This work establishes a cellular and molecular framework of AA feeding initiation and highlights redundancy in aversive pathways that regulate AA feeding.

Sleep to remember, sleep to protect: increased sleep spindle and theta activity predict fewer intrusive memories after analogue trauma
Recent evidence shows a strong correlative link between sleep disturbances and intrusive memories after traumatic events, presumably due to insufficient (nocturnal) memory integration. However, the underlying mechanisms of this link and the role of specific neural activities during sleep are poorly understood so far. Here, we investigated how the intra-individual affective response to an experimental trauma predicts changes in oscillatory activity during subsequent sleep and how these changes predict the processing of the experimental trauma. In a randomized within-subject comparison, twenty-two female, healthy participants (23.14 {+/-} 2.46 years) watched a well-validated film clip including traumatic contents and a neutral film clip before bedtime on two separate nights. Heart rate was recorded during the film clips and nocturnal brain activity was recorded using 64-channel high-density EEG during subsequent nights. Intrusive memories were assessed via a seven-days diary and negative affect was assessed using laboratory trauma film reminders one week after the trauma film. An increased intra-individual heart rate during the trauma film predicted higher intra-individual sleep spindle amplitude the following night. Increased theta activity (4.25 - 8 Hz) during rapid eye movement (REM) sleep after the trauma film predicted fewer trauma film related intrusive memories and negative affect. Likewise, an increase in sleep spindles after the trauma film predicted fewer trauma film related intrusive memories. Our findings suggest that an experience-dependent up-regulation of these nocturnal oscillatory activity patterns, which are known to be involved in adaptive memory consolidation processes, serves as a protective factor against trauma-related intrusive memory development. Particularly, increased theta activity during REM sleep and sleep spindle activity seem to be of importance here.

A proposal for unifying statistical learning at different scales: Long-Horizon Associative Learning
Sensory inputs often display complex temporal interdependencies that typically conform to a latent underlying arrangement, whose learning facilitates the efficient interaction with the environment. However temporal dependencies may cover a large range of scales, from consecutive items (Saffran et al., 1996), to relations in longer sequences (Dehaene et al., 2015; Schapiro et al., 2013). Whereas numerous models have been proposed to explain statistical learning at different scales (Fiser and Lengyel, 2022), we argue here that a single and unifying model can account for the different scales of statistical learning including, adjacent and non-adjacent transitions as well as network structures, even in the absence of first order transition probability information. Based on behavioral and MEG results, we previously showed that a long-horizon associative learning process (a biologically plausible implementation of successor representation, or equivalently the Free-Energy Minimization Model (FEMM) originally proposed by Lynn and colleagues (2020a)) was able to explain learning based on local statistical properties but also based on high-order network properties (Benjamin et al., 2024, 2023a). Here, we extend our proposal and describe how this long-term associative learning model accounts for various results from the literature with different scales of dependency between elements. Long-horizon associative learning thus provides a unified framework that spans diverse statistical scales, offering a unique explanation of literature results. We thus aim at replacing the numerous metrics described in the statistical learning literature, each tuned to a specific scale and that occasionally conflict with each other by this unique parsimonious approach.

Pathological tau activates inflammatory nuclear factor-kappa B (NF-κB) and pT181-Qβ vaccine attenuates NF-κB in PS19 tauopathy mice
Tau regulates neuronal integrity. In tauopathy, phosphorylated tau detaches from microtubules and aggregates, and is released into the extracellular space. Microglia are the first responders to the extracellular tau, a damage associated molecular pattern (DAMP), which can be cleared by proteostasis and activate innate immune response gene expression by nuclear factor kappa B (NFkB). However, longitudinal NFkB activation in tauopathies and whether pathological tau (pTau) contributes to NF-kB activity is unknown. Here, we tau oligomers from human Alzheimers disease brain (AD-TO) activate NFkB in mouse microglia and macrophages reducing the IkBa via promoting its secretion in the extracellular space. NFkB activity peaks at 9- and 11-months age in PS19Luc+ and hTauLuc+ mice, respectively. Reducing pTau via pharmacological (DOX), genetic (Mapt knockout) or antibody-mediated neutralization (immunization with pT181-Qb vaccine) reduces NFkB activity, and together suggest pTau is a driver of NFkB and chronic neuroinflammation tauopathies.

N-terminal oligomerization drives HDAC4 nuclear condensation and neurodevelopmental dysfunction in Drosophila
Histone deacetylase four (HDAC4) undergoes dynamic nucleocytoplasmic shuttling, which is important in the regulation of its activity. However, aberrant nuclear accumulation of HDAC4 is associated with both neurodevelopmental and neurodegenerative disease, and in our Drosophila model, impairs normal neuronal development. Upon nuclear accumulation, HDAC4 forms biomolecular condensates, previously termed aggregates, that correlate with the severity of defects in development of the Drosophila mushroom body and adult eye. Here we determined that nuclear condensation of HDAC4 is dependent on self-oligomerization, and that impairing oligomerization reduces condensation and the severity of neurodevelopmental phenotypes in Drosophila. HDAC4 condensates are highly dynamic and are stabilized by the presence of MEF2, which promotes their formation and coalescence, ultimately exacerbating phenotypic severity. These data provide insight into the role of HDAC4 condensates in normal neuronal function and suggest that their disruption may contribute to the onset or progression of neuronal disease. Consequently, targeting oligomerization of HDAC4 and its interaction with MEF2 present potential therapeutic strategies for diseases associated with HDAC4 nuclear accumulation.

Sustained attention is more closely related to long-term memory than to attentional control
Individuals differ in their ability to sustain attention. However, whether differences in sustained attention reflect differences in processes related to attentional control and working memory or long-term memory (LTM) remains underexplored. In Experiment 1, we conducted an online study (n = 136) measuring participants' sustained attention, attention control and working memory, and LTM. We measured sustained attention with an audio-visual continuous performance task (avCPT) in which participants responded to images while inhibiting responses to infrequent targets; attention control and working memory with Flanker, change localization, and Simon tasks; and LTM with recognition and source memory tests. Factor analyses revealed that sustained attention formed a distinct factor from attention control and working memory and LTM. Individual differences in the sustained attention factor robustly predicted individual differences in LTM and, to a lesser extent, attention control and working memory. In Experiment 2, to test how neural signatures of sustained attention related to attention control and working memory and LTM, we analyzed fMRI functional connectivity patterns collected as 20 participants performed the avCPT. A pre-trained connectome-based model of sustained attention predicted participants' performance on out-of-scanner LTM, but not attention control and working memory, tasks. Together these results suggest that individual differences in sustained attention, although correlated with attention control and working memory, are more closely related to LTM.

The Endo-GeneScreen Platform Identifies Drug-Like Probes that Regulate Endogenous Protein Levels within Physiological Contexts
Traditional phenotypic drug discovery platforms have suffered from poor scalability and a lack of mechanistic understanding of newly discovered phenotypic probes. To address this, we created Endo-GeneScreen (EGS), a high-throughput enabled screening platform that identifies bioactive small molecules capable of regulating endogenous protein expression encoded by any preselected target gene within a biologically appropriate context. As a proof-of-concept, EGS successfully identified drug candidates that up-regulate endogenous expression of neuronal Syngap1, a gene that causes a neurodevelopmental disorder when haploinsufficient. For example, SR-1815, a previously unknown and undescribed kinase inhibitor, alleviated major cellular consequences of Syngap1 loss-of-function by restoring normal SynGAP protein levels and dampening neuronal hyperactivity within haploinsufficient neurons. Moreover, we demonstrate that EGS assays accelerate preclinical development of identified drug candidates and facilitate mode-of-action deconvolution studies. Thus, EGS identifies first-in-class bioactive small molecule probes that promote biological discovery and precision therapeutic development.

Similar but different: ERP evidence on the processing of mental and physical experiencer verbs in Malayalam.
The study reported here was conducted to investigate the neurophysiological correlates of processing two types of subject experiencer verbs, namely mental experiencer verbs and physical experiencer verbs in Malayalam, a South Dravidian language. Event-related brain potentials (ERPs) were recorded as twenty-eight first-language speakers of Malayalam read intransitive sentences with the two types of experiencer verbs. Critical stimuli were either fully acceptable, whereby the subject case matched the requirements of the verb, or unacceptable, whereby the subject case violated the requirements of the verb. A linear mixed-models analysis confirmed negativity effects in the time window 400-800 ms for mental and physical experiencer verbs. Post-hoc analyses revealed that the negativity peaked relatively early for mental experiencer verbs, whereas relatively late for physical experiencer verbs. Further, the sentence-final acceptability of trials modulated the ERPs in non-anomalous conditions but not in violation conditions, and this modulation qualitatively differed between mental and physical experiencer verbs. These results suggest that, whilst a qualitatively similar mechanism is involved in the processing of both kinds of experiencer verbs, subtle but robust differences are inherent in processing mental versus physical experiencer verbs in Malayalam. Keywords: Mental experiencer verbs, Physical experiencer verbs, N400, Malayalam, Dative subjects

HortaCloud: An Open and Collaborative Platform for Whole Brain Neuronal Reconstructions
HortaCloud is a cloud-based, open-source platform designed to facilitate the collaborative reconstruction of long-range projection neurons from whole-brain light microscopy data. By providing virtual environments directly within the cloud, it eliminates the need for costly and time-consuming data downloads, allowing researchers to work efficiently with terabyte- scale volumetric datasets. Standardization of computational resources in the cloud make deployment easier and more predictable. The pay-as-you-go cloud model reduces adoption barriers by eliminating upfront investments in expensive hardware. Finally, HortaCloud's decentralized architecture enables global collaboration between researchers and between institutions.

Episodic memory facilitates flexible decision making via access to detailed events
Our experiences contain countless details that may be important in the future, yet we rarely know which will matter and which won't. This uncertainty poses a difficult challenge for adaptive decision making, as failing to preserve relevant information can prevent us from making good choices later on. One solution to this challenge is to store detailed memories of individual experiences that can be flexibly accessed whenever their details become relevant. By allowing us to store and recall specific events in vivid detail, the human episodic memory system provides exactly this capacity. Yet whether and how this ability supports adaptive behavior is poorly understood. Here we aimed to determine whether people use detailed episodic memories to make decisions when future task demands are uncertain. We hypothesized that the episodic memory system's ability to store events in great detail allows us to reference any of these details if they later become relevant. We tested this hypothesis using a novel decision making task where participants encoded individual events with multiple features and later made decisions based on these features to maximize their earnings. Across four experiments (total n = 472), we found that participants referenced episodic memories during decisions in feature-rich environments, and that they did so specifically when it was unclear at encoding which features would be needed in the future. Overall, these findings reveal a fundamental adaptive function of episodic memory, showing how its rich representational capacity enables flexible decision making under uncertainty.

Co-release of opposing signaling molecules from cortical neurons controls the escalation and release of aggression
Prolonged social isolation induces a distinct state characterized by numerous impacts on behavior, including increased aggression and altered social behaviors, but the contributions of cortical circuits to these behaviors are poorly understood. Here, we find that social isolation promotes aggression and increases investigatory behaviors leading up to aggression in both males and female mice. Genetic characterization of the neuropeptidergic population of Tachykinin-2 expressing (Tac2+) neurons in the medial prefrontal cortex (mPFC) reveals a population of predominately early-layer GABAergic neurons that are activated by aggressive encounters in isolated mice. Cells expressing the Neurokinin 3 receptor, which binds the peptide product of Tac2, are similarly activated by aggressive interactions in isolated mice. Loss of function perturbations targeting the co-release of Neurokinin B (NkB), the stimulatory peptide encoded by the gene Tac2, and the inhibitory neurotransmitter GABA from mPFC Tac2+ neurons, reveals dissociable functions for each signaling molecule in the distinct behaviors that tile an aggressive encounter. GABA transmission form Tac2+ neurons controls the release of aggression, whereas Tac2/NkB signaling controls the investigatory behaviors escalating to aggression. These findings reveal dissociable roles for opposing signaling molecules released from the same neuron in the control over aggression, suggesting a neurochemical mechanism by which internal states may exert coordinated, sequential effects on a broad array of behaviors.

Glial Contribution to the Pathogenesis of Post-Operative Delirium Revealed by Multi-omic Analysis of Brain Tissue from Neurosurgery Patients
Post-operative delirium (POD) is a common complication after surgery especially in elderly patients, characterized by acute disturbances in consciousness and cognition, which negatively impacts long-term outcomes. Effective treatments remain elusive due to the unclear pathophysiology of POD. To address the knowledge gap, we investigated DNA methylation profiles and gene expression changes in brain cells from POD and non-POD patients who underwent brain resection surgery for medication refractory epilepsy. DNA methylation analysis revealed alteration in epigenetic status of immune and inflammation-related genes. Single-nucleus RNA sequencing (snRNAseq) identified POD-specific glial cell alterations, particularly in microglia, where neuroinflammation was strongly enhanced, consistent with epigenetic findings. Astrocytes exhibited changes in synapse-related functions and migration. Furthermore, downstream analysis indicated similarities between POD-associated glial cell states and pathologies such as encephalitis and dementia. Overall, this study-the first multi-omics analysis of brain tissue from POD patients-provides direct evidence of glial cell contributions to POD pathogenesis, and highlights potential therapeutic targets.

The entorhinal spatial map integrates visual identity information of landmarks
The location and identity of landmarks provide spatial and nonspatial information of an environment, respectively, to guide spatial navigation. While the medial entorhinal cortex (MEC) is essential for representing spatial information, it is unclear whether it also encodes landmark identity. Here, we conducted two-photon calcium imaging of the MEC when mice navigated in multiple virtual environments, and discovered a general ability of the MEC to encode landmark identity through cue cells, which responded to individual landmarks during virtual navigation. Cue cells represented landmark identity by exhibiting more distinct activity patterns between visually disparate landmarks than identical ones. The representation was modulated by the spatial shift of cue cell activity relative to landmark location. Moreover, the identity encoding by the same cue cell population changed between different environments but was maintained within the same environment despite increased experience. In contrast, landmark location encoding by cue cells was regulated by experience, suggesting different mechanisms underlying the encodings of landmark identity and location. Finally, compared to cue cells, grid cells weakly encoded landmark identity but more robustly encoded landmark location. Thus, the MEC integrates both spatial and nonspatial information during navigation, but potentially through different circuit mechanisms.

Processing Ergativity in Compound Light Verb Constructions: Electrophysiological Evidence from Hindi
Ergativity marks subject arguments as agents of a transitive event and thereby signals verbal transitivity and influences language comprehension. We report here on an event-related brain potentials (ERP) study in Hindi, in which we investigated this interconnection to ascertain whether the ergative case as a processing cue and its ERP correlates can be generalized across and within ergative languages. The case marking on the subject argument (ergative or nominative case) in our study either matched or mismatched with the transitivity of the light verb (transitive or intransitive) in compound light verb constructions. Ergative case violations due to an intransitive light verb evoked an N400 effect, whereas nominative case violations due to a transitive light verb elicited a P600 effect. The results reveal neurophysiological differences in the processing of ergative and nominative case alignment modulated by the transitivity of the light verbs. The findings highlight the need for cross-linguistic research to aim beyond universality and elucidate the mechanism underlying the processing of language-specific structural variations.

Crossmodal Interaction of Flashes and Beeps Across Time and Number Follows Bayesian Causal Inference
Multisensory perception requires the brain to dynamically infer causal relationships between sensory inputs across various dimensions, such as temporal and spatial attributes. Traditionally, Bayesian Causal Inference (BCI) models have generally provided a robust framework for understanding sensory processing in unidimensional settings where stimuli across sensory modalities vary along one dimension such as spatial location, or numerosity (Samad et al., 2015). However, real-world sensory processing involves multidimensional cues, where the alignment of information across multiple dimensions influences whether the brain perceives a unified or segregated source. In an effort to investigate sensory processing in more realistic conditions, this study introduces an expanded BCI model that incorporates multidimensional information, specifically numerosity and temporal discrepancies. Using a modified sound-induced flash illusion (SiFI) paradigm with manipulated audiovisual disparities, we tested the performance of the enhanced BCI model. Results showed that integration probability decreased with increasing temporal discrepancies, and our proposed multidimensional BCI model accurately predicts multisensory perception outcomes under the entire range of stimulus conditions. This multidimensional framework extends the BCI models applicability, providing deeper insights into the computational mechanisms underlying multisensory processing and offering a foundation for future quantitative studies on naturalistic sensory processing.

An In Vivo Model of Alpha-Synuclein Spread from Gut to Brain
Background: Parkinson's disease is a progressive neurodegenerative disorder characterized by the presence of pathological aggregation of the protein alpha-synuclein and the loss of dopaminergic neurons in the substantia nigra. There is evidence that misfolding and propagation of alpha-synuclein aggregates through networks of interconnected neurons is responsible for the pathological spread and progress neuron loss. However, in vivo models demonstrating such pathological progression remain elusive. Results: This study utilizes a zebrafish model in order to interrogate the mechanisms of alpha- synuclein toxicity and spread. We describe the development of a zebrafish model of endogenous neuronal human alpha-synuclein expression that causes, in young fish, behavioral and neuronal changes as well as microglia activation. In aged fish, alpha-synuclein expression induces a slow but progressive pathological phenotype manifesting in neuron loss within the gut and the CNS. This model is further utilized to seed gut pathology by incorporating a novel method of feeding human alpha-synuclein preformed fibrils in order to initiate protein misfolding at an early age. The combination of endogenous neuronal expression of alpha-synuclein and the exogenous addition of misfolded protein facilitates the development of brain pathology and subsequent neuron loss in the CNS. In addition to the pathological alterations induced with the fibril feeding model, genetic changes were identified by single cell RNA sequencing. These gene changes resulted in pathway alteration that implicate neurodegenerative disease processes. Conclusion: This model of alpha-synuclein pathology is useful for understanding mechanisms underlying disease initiation and can replicate the progressive development of pathological synuclein accumulation. It has the potential to induce neuron to neuron spread and also offers a way to explore what interventions may prevent such pathological progression.

The Pesticide Chlorpyrifos Increases the Risk of Parkinson's Disease
Background and Purpose: Pesticides have been associated with an increased risk of Parkinson's disease (PD), but it is unclear which specific pesticides contribute to this association and whether it is causal. Since chlorpyrifos (CPF) exposure has been implicated as a risk factor for PD, we investigated its association to incident PD and if this association is biologically plausible using human, rodent, and zebrafish (ZF) studies. Methods: The association of CPF with PD was assessed using the UCLA PEG study (829 PD and 824 control subjects), and proximity-based exposure estimates from living or working near agricultural CPF use. For the mammalian studies, 6 months old male C57BL/6 mice were divided into two groups, CPF and controls, for open field, rotarod, and wire hang behavioral testing. Mice were then exposed to CPF in an inhalation chamber (0.65-2.9 mg/m3/day) for 6 hrs./day 5 days/wk., whereas control mice were exposed to vehicle alone. Behavioral tests were performed before and 2.5 months after CPF exposure following a 3-day washout. Mice were then perfused for immunohistochemical analysis. For the mechanistic studies, ZF embryos were treated with CPF (250 nM) 24 hours post fertilization for 5-7 days. Behavioral testing was performed using the Viewpoint Imaging System. Neuronal loss and microglial activation were determined using immunohistochemistry. Neuronal autophagic flux was determined using autophagy modulators in GFP-LC3 transgenic ZF and Western blots. Results: Long-term residential CPF exposure was linked to an increased risk of developing PD with an odds ratio of 2.68 (CI 1.58-4.55). Mice exposed to aerosolized CPF developed motor impairment and a significant loss of dopaminergic neurons in the substantia nigra and activation of microglia. TH positive neurons in the substantia nigra (SN) had significantly higher levels of phosphoserine 129 (pS129) alpha-synuclein (alpha-syn), a marker for pathological phosphorylated alpha-syn, and ubiquitin. In contrast, neither pS129 &alpha-syn or ubiquitin accumulated in TH neurons in the VTA after CPF exposure. Consistent with the mice data, CPF exposure resulted in impairment of locomotor activity and selective loss of aminergic neurons in ZF. We also found an increase in neuronal apoptosis and microglial activation. Importantly, dopamine neuron loss was found to be at least partially dependent on gamma1-synuclein (closest functional homologue to human alpha-syn) as neuronal loss did not occur in gamma1-synuclein knockout ZF. Using an in vivo ZF assay, we found impaired autophagic flux and an increase in lysosomal labelling within the zebrafish brain. CPF exposure also led to elevated gamma1-synuclein and p62 (autophagic cargo protein) levels consistent with impaired degradation. Furthermore, induction of autophagy was protective, supporting the hypothesis that impaired autophagic flux is at least partially responsible for neuron loss following CPF exposure. Conclusions: CPF exposure is associated with an increased risk of developing PD and this association is likely causal since PD-like pathology was recapitulated in animal models. Furthermore, impaired autophagic flux appears to underly this toxicity, a pathway implicated in the pathogenesis of PD.

Validating FOXO4 as a therapeutic target for protecting against ischemia-reperfusion-caused neuronal injury
Background: Previous data suggest that in the conditions of I/R in mice and the oxygen-glucose deprivation (OGD) in cell cultures, FOXO4 facilitates inflammation and oxidative stress in non-brain tissues, indicating that downregulation of FOXO4 may be neuroprotective in I/R-induced injury in the brain. However, this possibility has not been tested in the cerebral I/R condition. Method: FOXO4 knockout (KO) and wild-type (WT) primary neuronal cultures were treated with an oxidative stress inducer, menadione (MD), or OGD, and then cell viability was assessed via ATP and MTT assays. The KO and WT mice at 2-3 months were subjected to one-hour (h) transient middle cerebral artery occlusion (tMCAO). Mice were sacrificed after 24 h for TTC staining or after 48 h for immunohistochemical staining. Alternatively, animals were allowed to survive for 1-10 days after tMCAO to test their functional recovery. Furthermore, using a structure-based approach combined with cell-based assays, we screened FOXO4 inhibitors and identified actinomycin D (ActD) as a potent FOXO4 inhibitor. We also tested the therapeutic role of ActD in both in vitro and in vivo models of ischemic stroke. Result: KO of FOXO4 reduced the infarct volume, improved animal survival, decreased neurological deficits, and enhanced functional recovery compared to WT mice. Immunohistochemical staining of astrocytes and microglia revealed that KO brains showed a reduced number of astrocytes and microglia in the peri-infarcted area two days after I/R. Western blot analysis of proinflammatory cytokines, IL-1?, IL-6, and TNF-?, indicated decreased levels of proinflammatory cytokines two days following I/R. The identified FOXO4 inhibitor, ActD, attenuated oxidative stress and OGD-induced neuronal death. ActD also reduced neuronal injury of the brain and enhanced functional recovery in WT mice following tMCAO. Conclusion: We conclude that disrupting FOXO4 is neuroprotective and the identified inhibitor, ActD, may be a therapeutic agent for treating ischemic stroke induced brain injury.

Long-term neuron tracking reveals balance of stability and plasticity in functional properties
Neural stability is essential for executing learned motor behaviors while plasticity provides the flexibility needed to adapt to new tasks and environments. Although low-dimensional neural population dynamics exhibit long-term stability, the extent to which individual neurons retain their functional properties over time and balance the need for both stability and plasticity remains an open question. Tracking individual neurons across multiple recording sessions is crucial to addressing this question, yet conventional methods face challenges such as electrode drift, waveform variability, and large inter-electrode distances that limit the number of channels a neuron is observed on. Here, we introduce a waveform-based neuron tracking method optimized for standard microelectrode arrays, enabling the identification of the same neurons across sessions without relying on spatial overlap, a strategy commonly leveraged with high-density electrode arrays. We apply this method to assess the longitudinal stability of multiple neural properties, including firing rates, inter-spike intervals, tuning properties, and spike-field interactions. Our findings reveal that while spike waveform properties remain stable, certain functional properties such as ISI and tuning can exhibit gradual shifts, suggesting a balance between neural stability and plasticity. Understanding the persistence of individual neural signals provides insight into learning and adaptation while advancing the study of neural stability and plasticity over extended timescales. Beyond basic neuroscience, this framework has potential to enhance the long-term reliability of brain-machine interfaces and closed-loop deep brain stimulation systems that rely on chronic neural sensing.

A Bitopic mTORC Inhibitor Reverses Neural Phenotypes in a Tuberous Sclerosis Complex Murine Model of SEGA-like Hamartomas
Neural stem cells (NSCs) of the ventricular-subventricular zone (V-SVZ) generate diverse cell types including striatal glia during the neonatal period. NSC progeny uncouple stem cell-related mRNA transcripts from being translated during differentiation. We previously demonstrated that Tsc2 inactivation, which occurs in the neurodevelopmental disorder Tuberous Sclerosis Complex (TSC), prevents this from happening. Loss of Tsc2 causes hyperactivation of the protein kinase mechanistic target of rapamycin complex 1 (mTORC1), altered translation, retention of stemness in striatal glia, and the production of misplaced cytomegalic neurons having hypertrophic dendrite arbors. These phenotypes model characteristics of TSC hamartomas called subependymal giant cell astrocytomas (SEGAs). mTORC1 inhibitors called rapamycin analogs (rapalogs) are currently used to treat TSC and to assess the role of mTORC1 in regulating TSC-related phenotypes. Rapalogs are useful for treating SEGAs. However, they require lifelong application, have untoward side effects, and resistance may occur. They also incompletely inhibit mTORC1 and have limited efficacy. Rapalink-1 is a bitopic inhibitor developed to overcome the limitations of rapalogs by linking rapamycin to a second-generation mTOR ATP competitive inhibitor, MLN0128. Here we explored the effect of Rapalink-1 on a TSC hamartoma model. The model is created by neonatal electroporation of mice having conditional Tsc2 genes. Prolonged Rapalink-1 treatment could be achieved with 1.5 or 3.0 mg/Kg injected intraperitoneally every five days. Rapalink-1 inhibited the mTORC1 pathway, decreased cell size, reduced neuron dendrite arbors, and reduced hamartoma size. In conclusion, these results demonstrate that cellular phenotypes in a TSC SEGA model are reversed by Rapalink-1 which may be useful to resolve TSC brain hamartomas.

Intranasal administration of isradipine preferentially targets the brain
Parkinson's disease (PD) is the second most common neurodegenerative disease. Despite a concerted effort on the part of the scientific community, there is no proven strategy for slowing PD progression. Nevertheless, there are several potential drug targets that if functionally modified could alter disease course. Preclinical, epidemiological and clinical trial data suggest that Cav1 Ca2+ channels are one such target. Dihydropyridines (DHPs) are voltage-dependent, negative allosteric modulators of Cav1 Ca2+ channels that are approved for human use. However, the brain concentration of DHPs that can be safely achieved in humans with oral dosing is limited because of the widespread distribution of these channels, particularly in the vasculature. Intranasal administration of DHPs is a potential alternative delivery strategy that has been used with compounds that have similar limitations. To test the viability of this drug administration strategy, mice were intranasally or orally administered the DHP isradipine mixed in one of three vehicles. Plasma and brain concentrations of isradipine were then determined using liquid chromatography/mass spectroscopy at subsequent times. These studies demonstrated that intranasal administration of isradipine was able to achieve higher brain concentrations than those in the plasma, and these differences persisted for hours. Thus, intranasal administration of DHPs could be used to achieve high levels of Cav1 Ca2+ channel inhibition in the brain without producing unwanted peripheral side-effects.