bioRxiv Subject Collection: Neuroscience's Journal

Tryptophan metabolites as biomarkers to predict the severity and prognosis of acute ischemic stroke patients
Background: A growing body of evidence indicates alterations in metabolite levels and enzyme activities associated with the conversion of tryptophan (TRP) throughout the course of cerebral ischemia. In this study we aim to explore the potential relationship between TRP metabolism and clinical prognosis in acute ischemic stroke (AIS) patients of mainland China. Methods: Blood samples were obtained from a cohort of 304 AIS patients. The concentrations of ten TRP metabolites were quantified utilizing liquid chromatography-tandem mass spectrometry. LASSO regression and random forest algorithms were employed to identify key TRP metabolism parameters associated with prognosis. Results: The metabolites TRP, 5-hydroxytryptamine (5-HTP), 3-hydroxyanthranilic acid (3-HAA)/3-hydroxykynurenine (3-HKYN) showed a negative correlation with the NIHSS score, while 3-HKYN, kynurenic acid (KYNA), 3-HKYN/kynurenine (KYN), KYN/TRP, KYNA/KYN, 3-HKYN/TRP, N-formylkynurenine (NFK)/TRP and KYNA/TRP ratio exhibited a positive correlation with the NIHSS score. Three robust parameters related to TRP metabolism were identified. Multivariable logistic regression analysis, adjusted for covariates, revealed that TRP (odds ratio [OR] = 0.46, 95% confidence interval [CI]: 0.26 - 0.76, p = 0.004), the KYN/TRP ratio (OR = 2.06, 95% CI: 1.23 - 3.60, p = 0.008), and the KYNA/TRP ratio (OR = 2.15, 95% CI: 1.23 - 4.12, p = 0.014) were independently associated with poor functional prognosis. Conclusions: The results of this study indicate that TRP metabolism is associated with the severity and prognosis of AIS. The TRP, KYN/TRP ratio and KYNA/TRP ratio may serve as potential biomarkers for 3-month prognostic evaluation.

Metabolic state modulates risky foraging behavior via multiple branches of the insulin/IGF-1-like pathway in C. elegans
Foraging to acquire nutrients is an essential and sometimes risky behavior displayed by nearly all animals. Appropriately balancing foraging risks with nutrient requirements is pivotal for peak survival and reproduction, and metabolic state (i.e., how urgently the animal requires nutrients) is a strong modulator of risky foraging behavior. In this study, we asked what molecular signal allows C. elegans to change its foraging behavior in response to changes in its metabolic state. We used an assay of risky foraging behavior, where wild type worms increase risky foraging behavior after food deprivation, to screen for candidate genes. We found that DAF-2, the singular receptor in the C. elegans insulin/IGF-1 signaling (IIS) pathway, is necessary for worms to modulate risky foraging behavior in response to short-term food deprivation. Worms with mutations in genes upstream and downstream of daf-2 in the IIS pathway also exhibited a reduction in the effect of food deprivation. While a canonical understanding of the IIS pathway would suggest that the FOXO transcription factor DAF-16 is the primary downstream IIS pathway target, we found that DAF-16 was not required for worms to exhibit food-deprivation-driven changes in foraging behavior. Furthermore, we determined that the calsyntenin ortholog CASY-1, which allows DAF-2c to traffic to axons, is required for food deprivation to modulate risky foraging behavior. These results both validate the IIS receptor as a pivotal regulator of risky foraging behavior and suggest a multi-pronged downstream pathway. Overall, these data enrich our understanding of how organisms transduce metabolic state information to make vital decisions about when to engage in risky foraging behaviors.

Fractional and Geometric Neural Dynamics: Investigating Intelligence-Related Differences in EEG Symmetry and Connectivity
Understanding intelligence-related variations in electroencephalographic (EEG) activity requires advanced mathematical approaches capable of capturing geometric transformations and long-range dependencies in neural dynamics. These approaches may provide methodological advantages over conventional spectral and connectivity-based techniques by offering deeper insights into the structural and functional organization of neural networks. In this study, we integrate Clifford algebra, Noether's theorem and fractional calculus to analyze EEG signals from high- and low-IQ individuals, looking for key intelligence-related differences in cortical organization. Clifford algebra enables the representation of EEG signals as multivectors, preserving both magnitude and directional relationships across cortical regions. Noether's theorem provides a quantitative measure of symmetry properties linked to spectral features, identifying conserved functional patterns across distinct brain regions. Mittag-Leffler functions, derived from fractional calculus, characterize long-range dependencies in neural oscillations, allowing for the detection of memory effects and scale-invariant properties often overlooked by traditional methods. We found significant differences between high- and low-IQ individuals in geometric trajectories, hemispheric connectivity, spectral properties and fractional-order dynamics. High-IQ individuals exhibited increased spectral asymmetry, enhanced spectral differentiation, distinct geometric trajectories and greater fractional connectivity, particularly in frontal and central regions. In contrast, low-IQ individuals displayed more uniform hemispheric connectivity and heightened fractional activity in occipital areas. Mittag-Leffler fractional exponents further indicated that high-IQ individuals possessed more varied neural synchronization patterns. Overall, our multi-faceted approach suggests that intelligence-related neural dynamics are characterized by an asymmetric, functionally specialized and fractionally complex cortical organization. This results in significant differences in network topology, efficiency, modularity and long-range dependencies.

Cortical thinning in temporal pole, a core region in Alzheimer's disease, in non-demented, middle-aged APOE-e4 and PICALM-AA/AG carriers
The symptoms of Alzheimer's disease (AD) are caused by neurodegeneration and atrophy in particular brain regions, especially in the temporal cortex. However, the influence of genetic risk on cortical thickness in non-demented individuals prior to disease onset remains unclear. This study aimed to explore the relationship between two AD risk genes (APOE/PICALM) and cortical thickness in selected regions of interest (ROIs) in non-demented, middle-aged individuals. Sixty-nine (N = 69) participants (34 females, 35 males; age: 55.45{+/-}3.19) underwent magnetic resonance imaging (MRI). They were divided into three groups based on their AD risk. Cortical thickness was analyzed using CAT12 software (surface-based morphometry with the Destrieux atlas) based on T1-weighted MR images in five ROIs referred as "the cortical signature of AD" in previous studies. APOE-e4 with PICALM-AA/AG carriers (A+P-) are characterized by a thinner cortex in the right temporal pole compared to non-carriers, controlling for sex. No other differences in cortical thickness were found in the selected ROIs. The direction of the findings aligns with existing literature reporting cortical thinning in amyloid-positive individuals, as well as in patients with mild cognitive impairment and Alzheimer's disease when compared to control groups.

Super Quantum Neuroelectromagnetic Dynamics of Action and Percept Potentials
The spatiotemporal selectivity of neurons to sensory stimuli that underlie the center and surround receptive fields represents the anticommutative and, thus, symmetry that defines sensorimotor transformation. However, owing to the nonabelian nature of the irresponsiveness of neurons to sensory stimuli characterized by inexcitations, symmetry and, thus, transformation does not become apparent. Hence, a neuroscientific model that describes the precise mechanism of the nonabelian gauge group in the brain is unknown. Using quantum field theory, we show visuomotor transformation of natural images in which the superposition of opposite parallel cortical columns creates visual fields and annihilates motor fields. The creation and annihilation operators, magnetic and electric charged particles, are opposed inertia systems that act on each other by raising and lowering each other's particles, leading to momentum-energy trade-offs, in our case, retinotopic gain and retinomotion loss, and vice versa. The magnetic charged particles -, +, -, intrinsic to a magnetic neuron, nabla, are predicted to exist opposite parallel to the electrically charged particles +, -, + of the electrical pyramidal neuron in the neocortex. The implication is that the physical neocortex or electric brain is in concert with a nonphysical complex neocortex or magnetic brain that is hardly detectable but much alive and proactive.

A computational architecture incorporating shallow brain networks: integrating parallel cortical and subcortical processing
Artificial neural networks commonly have deep hierarchical structures that were originally inspired by the neuroanatomical evidence of cortico-cortical connectivity pattern found in the mammalian brain. Largely neglected in those models are non-hierarchical aspects of brain architecture, namely the subcortical pathways and the interactions between cortical and subcortical areas regardless of their hierarchical locations. Inspired by this principle, we present a computational model combining cortical hierarchical processing with subcortical pathways based on neuroanatomical evidence. We show the versatility of our model by implementing the cortical hierarchy in two alternative ways-a convolutional feedforward network and a predictive coding network. Both model variants can replicate behavioral observations in humans and monkeys on a perceptual context-dependent decision-making task. The model also reveals that subcortical structures lead decisions for easy trials while the more complex hierarchical network is necessary for the harder trials. Our results suggest that the parallel cortico-subcortical processing explored in the model represents a fundamental property that cannot be neglected in understanding the computational principles used by the brain.

iPSC-Derived Cerebral Organoids Reveal Mitochondrial, Inflammatory and Neuronal Vulnerabilities in Bipolar Disorder
Bipolar disorder (BD) is increasingly recognized as a disorder with both mitochondrial dysfunction and heightened inflammatory reactivity, yet their contribution to neuronal activity remains unclear. To address these gaps, this study utilizes iPSC-derived cerebral organoids (COs) from BD patients and healthy controls to model disease-specific metabolic and inflammatory dysfunction in a physiologically relevant system. BD COs exhibited mitochondrial impairment, dysregulated metabolic function, and increased nod-leucine rich repeat and pyrin domain containing protein 3 (NLRP3) inflammasome activation sensitivity. Treatment with MCC950, a selective NLRP3 inhibitor, effectively rescued mitochondrial function and reduced inflammatory activation in both BD and control COs. Additionally, a Bioactive Flavonoid Extract (BFE) was explored as a potential therapeutic, demonstrating partial rescue of inflammasome activation. These findings highlight a mitochondria-inflammasome axis in BD pathophysiology and establish a novel platform for studying BD-associated cellular mechanisms, ultimately bridging the gap between molecular dysfunction and therapeutic development.

Compositional architecture: Orthogonal neural codes for task context and spatial memory in prefrontal cortex
The prefrontal cortex (PFC) is crucial for maintaining working memory across diverse cognitive tasks, yet how it adapts to varying task demands remains unclear. Compositional theories propose that cognitive processes in neural network rely on shared components that can be reused to support different behaviors. However, previous studies have suggested that working memory components are task specific, challenging this framework. Here, we revisit this question using a population-based approach. We recorded neural activity in macaque monkeys performing two spatial working memory tasks with opposing goals: one requiring movement toward previously presented spatial locations (look task) and the other requiring avoidance of those locations (no-look task). Despite differences in task demands, we found that spatial memory representations were largely conserved at the population level, with a common low-dimensional neural subspace encoding memory across both tasks. In parallel, task identity was encoded in an orthogonal subspace, providing a stable and independent representation of contextual information. These results provide neural evidence for a compositional model of working memory, where representational geometry enables the efficient and flexible reuse of mnemonic codes across behavioral contexts while maintaining an independent representation of context.

Untangling dopamine and glutamate in the ventral tegmental area
Ventral tegmental area (VTA) dopamine neurons are of great interest for their central roles in motivation, learning, and psychiatric disorders. While hypotheses of VTA dopamine neuron function posit a homogenous role in behavior (e.g., prediction error), they do not account for molecular heterogeneity. We find that glutamate-dopamine, nonglutamate-dopamine, and glutamate-only neurons are dissociable in their signaling of reward and aversion-related stimuli, prediction error, and electrical properties. In addition, glutamate-dopamine and nonglutamate-dopamine neurons differ in dopamine release dynamics. Aversion-related recordings of all dopamine neurons (not considering glutamate co-transmission) showed a mixed response that obscured dopamine subpopulation function. Within glutamate-dopamine neurons, glutamate and dopamine release had dissociable contributions toward reward and aversion-based learning and performance. Based on our results, we propose a new hypothesis on VTA dopamine neuron function: that dopamine neuron signaling patterns and their roles in motivated behavior depend on whether or not they co-transmit dopamine with glutamate.

Combining Sampling Methods with Attractor Dynamics in Spiking Models of Head-Direction Systems
Uncertainty is a fundamental aspect of the natural environment, requiring the brain to infer and integrate noisy signals to guide behavior effectively. Sampling-based inference has been proposed as a mechanism for dealing with uncertainty, particularly in early sensory processing. However, it is unclear how to reconcile sampling-based methods with operational principles of higher-order brain areas, such as attractor dynamics of persistent neural representations. In this study, we present a spiking neural network model for the head-direction (HD) system that combines sampling-based inference with attractor dynamics. To achieve this, we derive the required spiking neural network dynamics and interactions to perform sampling from a large family of probability distributions - including variables encoded with Poisson noise. We then propose a method that allows the network to update its estimate of the current head direction by integrating angular velocity samples - derived from noisy inputs - with a pull towards a circular manifold, thereby maintaining consistent attractor dynamics. This model makes specific, testable predictions about the HD system that can be examined in future neurophysiological experiments: it predicts correlated subthreshold voltage fluctuations; distinctive short- and long-term firing correlations among neurons; and characteristic statistics of the movement of the neural activity "bump" representing the head direction. Overall, our approach extends previous theories on probabilistic sampling with spiking neurons, offers a novel perspective on the computations responsible for orientation and navigation, and supports the hypothesis that sampling-based methods can be combined with attractor dynamics to provide a viable framework for studying neural dynamics across the brain.

Corticotropin-Releasing Factor in the Nucleus Accumbens Does Not Drive High Levels of Cocaine Consumption
Uncovering the neurobiological processes underlying substance use disorder informs future therapeutic interventions. Prior research implicates the corticotropin releasing factor (CRF) system as a major player in a wide variety of substance use disorder -like phenotypes. However, the complexity of the CRF system in regard to brain region specific effects and experience-dependent changes in activity is poorly understood. Employing a cocaine self-administration paradigm that induces escalation of cocaine consumption in a subset of subjects, we investigated the role of CRF activity in the Nucleus Accumbens (NAc) in cocaine-taking patterns both before and after chronic cocaine experience. Our results showed that pharmacologically inhibiting CRF-R1 in the NAc did not reduce cocaine consumption following escalation and genetically deleting CRF-R1 from cells in the NAc did not prevent escalation. Overall, this suggests that any effect of CRF activity driving escalation or high levels of cocaine consumption is not through its actions on CRF-R1 in the NAc.

Targeting anterior cingulate cortex with tDCS: an overview and analysis of electric field magnitude
The anterior cingulate cortex (ACC) is a brain region with a key role in various cognitive, emotional, and sensory processes. Given its extensive functional repertoire, modulating ACC activity to enhance cognitive functioning and alleviate symptoms of certain clinical conditions holds great potential. Over the past decades, transcranial direct current stimulation (tDCS) has gained popularity due to its ability to non-invasively affect the cortical excitability. Nevertheless, using tDCS to target regions located beneath superficial cortical areas, such as the ACC, could pose a challenge due to the unpredictable distribution of the electric field (E-field). To systematize the current state of evidence regarding the use of tDCS to modulate ACC activity, we conducted a systematic review focusing on analyzing the E-field distribution across the brain and its magnitude within the ACC as the region of interest. Our goal was to review the stimulation parameters used thus far and examine whether the E-field characteristics are linked to the observed effects. After the literature search and study selection, 14 studies were included in the review. Most of the studies were sham-controlled single-session experiments aiming to modulate specific cognitive processes in healthy adults. The most prominent process of interest was cognitive control, and most of the included studies observed behavioural effects. Our results show that cathodal stimulation led to significant results more frequently, regardless of E-field magnitude in ACC or specificity of E-field distribution throughout the brain. When it comes to anodal tDCS, more focal stimulation of the ACC was associated with a higher frequency of significant effects. We discuss these findings considering diverse methodological designs, the (un)specificity of ACC targeting, and other factors that could contribute to the variability of tDCS effects across studies.

Reproducible Brain Charts: An open data resource for mapping brain development and its associations with mental health
Major mental disorders are increasingly understood as disorders of brain development. Large and heterogeneous samples are required to define generalizable links between brain development and psychopathology. To this end, we introduce the Reproducible Brain Charts (RBC), an open data resource that integrates data from 5 large studies of brain development in youth from three continents (N=6,346; 45% Female). Confirmatory bifactor models were used to create harmonized psychiatric phenotypes that capture major dimensions of psychopathology. Following rigorous quality assurance, neuroimaging data were carefully curated and processed using consistent pipelines in a reproducible manner with DataLad, the Configurable Pipeline for the Analysis of Connectomes (C-PAC), and FreeSurfer. Initial analyses of RBC data emphasize the benefit of careful quality assurance and data harmonization in delineating developmental effects and associations with psychopathology. Critically, all RBC data - including harmonized psychiatric phenotypes, unprocessed images, and fully processed imaging derivatives - are openly shared without a data use agreement via the International Neuroimaging Data-sharing Initiative. Together, RBC facilitates large-scale, reproducible, and generalizable research in developmental and psychiatric neuroscience.

Endogenously generated Dutch-type Aβ nonfibrillar aggregates dysregulate presynaptic neurotransmission in the absence of detectable inflammation
APPE693Q transgenic mice develop aging-related learning deficits and accumulate endogenously generated nonfibrillar aggregates of A{beta} (NFA-A{beta}) and APP -carboxy terminal fragments. The APPE693Q mutation disrupts amyloid fibril formation, and no plaques develop in these mice. In the current study, the aging-related accumulation of NFA-A{beta} in APPE693Q mice was revealed by A11 immunohistochemistry and NFA-A{beta}-detecting cyclic D,L--peptide-FITC microscopy. The presynaptic termini of APPE693Q mice developed aging-related physiological abnormalities in post-tetanic potentiation, synaptic fatigue, and synaptic vesicle replenishment. Single-cell RNA sequencing showed that excitatory neurons exhibited the most altered transcriptomic profile, especially involving ''protein translation'' and ''oxidative phosphorylation''. Direct measurements of electron transport chain catalysis revealed reduction in mitochondrial complex I activity in Dutch mice. Microglial transcript analysis revealed no evidence of inflammation. The depletion or neutralization of both fibrillar and NFA-A{beta} may be needed for complete elimination of A{beta} toxicity.

Interpersonal synchronization as an objective measure of listening engagement
Listening engagement has received increasing attention for its role in effective communication and knowledge transfer. It encompasses a state of deep listening in which a person not only pays attention to a stimulus but is fully absorbed in it. Behavioral measures have been used to assess listening engagement; however, they have limitations and do not fully capture this multidimensional state. Measuring listening engagement objectively using brain and body signals is a compelling alternative. In particular, interpersonal synchronization-observed through synchronized physiological responses among listeners-offers a promising objective measure of this phenomenon. We measured brain, heart rate, and electrodermal activity synchronization between people who listened to engaging and non-engaging stories. As a ground truth, we also measured subjective listening engagement through a questionnaire. Results showed higher synchronization when participants listened to an engaging stimulus compared to a non-engaging one across different modalities of objective response. Furthermore, we found a significant correlation between synchronization measures and subjective engagement ratings. These results confirm that synchronization may serve as a reliable measure of listening engagement.

Relationships between GABA+ and Glx concentrations with age and inhibition in healthy older adults
Inhibition represents a core executive function which underlies the ability to suppress interfering and/or distracting stimuli, thereby building resistance against task-irrelevant information. However, the impact of ageing on inhibitory functioning and the potential role of neuroplasticity, largely driven by predominant excitatory (glutamatergic) and inhibitory (GABAergic) neurochemicals, remains poorly understood. In this study, we investigated age relationships with neurochemical concentrations (GABA+ and Glx) and examined the associations between these neurochemicals and inhibitory sub-components in the context of healthy ageing. To this end, participants completed three inhibition tasks (i.e., flanker, Stroop and go/no-go), each measuring a different sub-component process, via the PsyToolkit platform. MRS data was acquired in the sensorimotor (SM1; n=71, mean age (SD) = 68.3 (9.7) years, 39 females) and prefrontal (PFC; n=58, mean age (SD) = 67.6 (9.6) years, 30 females) regions using a HERMES sequence and analysed using the OSPREY pipeline. After correcting for gender and education, semi-partial correlations (rho) revealed no significant relationships between age and GABA+ or Glx concentrations in either the SM1 or PFC regions. Furthermore, through partial correlations (rho), after correcting for age, gender and education, we identified a significant negative relationship between SM1 Glx concentrations and go/no-go error rates, such that greater concentrations of Glx in the SM1 region were associated with greater accuracy on the go/no-go task. The null age-neurochemical results suggest that GABA+ and Glx may not uniformly decline during healthy ageing. This finding suggests that the relationship between older age and neurochemistry may be more nuanced than previously reported. In addition, our neurochemical-behavioural findings provide neurochemically-and-spatially specific evidence that SM1 Glx concentrations may be important for response inhibition. This result indicates a role for the glutamatergic system in supporting inhibition over the normal course of ageing.

Le Petit Prince (LPP) Multi-talker: Naturalistic 7T fMRI and EEG Dataset
Prior neuroimaging datasets using naturalistic listening paradigms have predominantly focused on single-talker scenarios. While these studies have been invaluable for advancing our understanding of speech and language processing in the brain, they do not capture the complexities of real-world multi-talker environments. Here, we introduce the "Le Petit Prince (LPP) Multi-talker Dataset", a high-quality, naturalistic neuroimaging dataset featuring 40 minutes of electroencephalogram (EEG) and 7T functional magnetic resonance imaging (fMRI) recordings from 26 native Mandarin Chinese speakers as they listened to both single-talker and multi-talker speech streams. Validation analyses conducted on both EEG and fMRI data demonstrate the dataset's high quality and robustness. Additionally, the dataset includes detailed transcriptions and prosodic and linguistic annotations of the speech stimuli, enabling fine-grained analyses of neural responses to specific linguistic and acoustic features. The LPP Multi-talker Dataset is well-suited for addressing a wide range of research questions in cognitive neuroscience, including selective attention, auditory stream segregation, and working memory processes in naturalistic listening contexts.

Derivation and analysis of human somatic sensory neuron subtypes facilitated through fluorescent hPSC reporters
Peripheral sensory neuropathy (PSN) is associated with several devastating neurological conditions, yet effective strategies to prevent or alleviate the consequences of PSN are nearly non-existent. A major challenge in the development of better therapeutic interventions is the lack of appropriate human model systems. Human induced pluripotent stem cell (hiPSC)-derived somatosensory neurons present a promising strategy to overcome this issue but remain of limited translational utility, in part due to the low efficiency and lack of sensory subtype selectivity of the existing sensory neuron derivation protocols. To improve upon iPSC-based somatosensory disease models, we here describe the generation and validation of a genetic toolset to fluorescently label all or distinct (nociceptor, low threshold mechanoreceptor, and proprioceptor) somatosensory subtypes. These new resources will be transformative for hPSC-based approaches in PSN disease modeling - a critical step towards translating new findings into clinically relevant therapeutic strategies.

New Insights into Epileptic Spasm Generation and Treatment from the TTX Animal Model
Currently, we have an incomplete understanding of the mechanisms underlying infantile epileptic spasms syndrome (IESS). However, over the past decade, significant efforts have been made to develop IESS animal models to provide much-needed mechanistic information for therapy development. Our laboratory has focused on the TTX model, in which tetrodotoxin (TTX) is infused into the neocortex of infant rats, producing a lesion at the infusion site and mimicking IESS resulting from acquired structural brain abnormalities. Subsequent electrophysiological studies showed that the epileptic spasms originate from neocortical layer V pyramidal cells. Importantly, experimental maneuvers that increase the excitability of these cells produce focal seizures in non-epileptic control animals but never produce them in TTX-infused epileptic rats; instead, epileptic spasms are produced in epileptic rats, indicating a significant transformation in the operations of neocortical networks. At the molecular level, studies showed that the expression of insulin-like growth factor 1 was markedly reduced in the cortex and this corresponded with a loss of presynaptic GABAergic nerve terminals. Very similar observations were made in surgically resected tissue from IESS patients with a history of perinatal strokes. Other experiments in conditional knockout mice indicated that IGF-1 plays a critical role in the maturation of neocortical inhibitory connectivity. This finding led to our hypothesis that the loss of IGF-1 in epileptic animals impairs inhibitory interneuron synaptogenesis and is responsible for spasms. To test this idea, we treated epileptic rats with the IGF-1-derived tripeptide (1-3)IGF-1, which was shown to act through IGF-1s receptor. (1-3)IGF-1 rescued inhibitory interneuron connectivity, restored IGF-1 levels, and abolished spasms. Thus (1-3)IGF-1 or its analogues are potential novel treatments for IESS following perinatal brain injury. We conclude by discussing our findings in the broader context of the often-debated final common pathway hypothesis for IESS.

Effects of Social Housing on Electrically Stimulated Dopamine Release in the Nucleus Accumbens Core and Shell in Female and Male Rats
Dopamine (DA) is a neurotransmitter that is important in the reward system and increased DA release is associated with rewarding properties of drugs. Highly addictive stimulants like methamphetamine (METH) increase DA release and block reuptake, causing the DA to stay in the synapse longer, enhancing its effects. Because the misuse of METH is increasing in the United States, it is important to investigate ways to protect against this highly addictive stimulant. Recent studies have shown that social support can be a protective factor against METH self-administration in females, but not males. Other studies using microdialysis have shown that socially housed females have lower DA release in the nucleus accumbens (NAc) compared to single housed females after treatment with METH. Additionally, researchers have shown that there are sex differences in stimulated DA release. The present study investigates whether social housing affects stimulated DA release after METH treatment. DA release in the NAc core and shell of socially housed and individually housed rats was measured using fast scan cyclic voltammetry (FSCV) with a chronic 16-channel carbon fiber electrode in the NAc. A stimulating electrode was aimed at the ventral tegmental area (VTA) to induce DA release in the NAc. The results showed that social housing enhances electrically stimulated DA release in males and that there was greater DA release in NAc core than shell in single males, but no difference in socially housed males. In females, social housing also enhanced ES DA release. In single females there was greater ES DA release in shell than in core. Additionally, in single housed females there was greater ES DA release over time, while the socially housed females had high ES DA release that remained stable over time. These results suggest that social housing protects females from sensitization, making single females more vulnerable to the addictive properties of METH.

Neural variability reliably and selectively encodes pain discriminability
Neural activity varies dramatically across time. While such variability has been associated with cognition, its relationship with pain remains largely unexplored. Here, we systematically investigated the relationship between neural variability and pain, particularly pain discriminability, in five large electroencephalography (EEG) datasets (total N = 489), collected from healthy individuals (Datasets 1-4) and patients with postherpetic neuralgia (PHN; Dataset 5) who had received painful or nonpainful sensory stimuli. We found robust correlations between neural variability and interindividual pain discriminability. These correlations were (1) replicable in multiple datasets, (2) pain selective, as no significant correlations were observed in nonpain modalities, and (3) clinically relevant, as they were partly disrupted in patients with PHN. Importantly, variability and amplitude of EEG signals were mutually independent and had distinct temporal and oscillatory profiles in encoding pain discriminability. These findings demonstrate that neural variability is a replicable and selective indicator of pain discriminability above and beyond amplitude, thereby enhancing the understanding of neural encoding of pain discriminability and underscoring the value of neural variability in pain studies.

Executive Functions in relation to Autonomic Control: An Overview of Neuropsychological Evaluation Methods
Executive functions are a set of cognitive processes essential for cognitive control and coordination, enabling the achievement of objectives. These functions include mental exploration of ideas, reasoning, logical conclusion drawing, discipline, decision making, thoughtful consideration before action, tackling unforeseen challenges, resisting temptations, and maintaining focus. Numerous neuropsychological tests assess executive functions in relation to different autonomic control pathways that regulate involuntary physiological processes. The complexity of the autonomic nervous system and the challenges in measuring it alongside cognitive assessments are significant. Issues such as subject movement, environmental changes, and time-consuming protocols further complicate this measurement. There is a notable lack of research on suitable neuropsychological tests for assessing executive functions across diverse autonomic regulatory states. This paper presents the most frequently used neuropsychological instruments in this context, aiming to guide the research community towards optimal tasks and administration protocols for concurrent autonomic nervous system measurement. The diversity of current executive function tests presents both opportunities and challenges. Some tests are better suited for simultaneous neurophysiological measurements due to their design, duration, and cognitive load, while others may interfere with or be influenced by such monitoring. This variability can lead to inconsistencies in findings and complicate result interpretation and comparison across studies of brain disorders. A significant drawback of using different tasks is the difficulty in comparing outcomes and conducting meta-analyses. Standardizing a smaller selection of tasks with consistent protocols would enhance research reliability, facilitate robust comparisons, and improve the overall quality of meta-analyses. To achieve this standardization, it is essential to first survey and describe the current landscape of executive function assessments in conjunction with autonomic nervous system measurements. Objective This paper aims to comprehensively analyze current instruments utilized in the assessment of executive functions, elucidating their advantages, limitations, and implications for future standardization initiatives. By systematically examining the most prevalent tools for evaluating executive functions in conjunction with autonomic nervous system measurements within clinical and experimental research settings, this review seeks to provide valuable insights for enhancing methodological consistency and advancing research in this area. Methods We searched for articles published using the PubMed database with the following terms: (neuropsychological test OR neuropsychological evaluation OR neuropsychological measure*) AND (executive functions OR EF OR executive function) AND (autonomic OR ANS OR parasympathetic OR PNS OR vagal OR "heart rate variability" OR HRV OR sympathetic OR HPA OR electrodermal OR RSA) Only the healthy population was chosen. There was no language restriction. Results 62 articles fulfilled all the inclusion criteria. The 5 neuropsychological tests most frequently used to evaluate executive functions in relation to autonomic regulation were: 1. Trail Making Test (TMT) B 2. The n-back Task including 2-back Task 3. Wisconsin Card Sorting Test 4. Stroop Test and its variants 5. Wechsler Adult Intelligence Scale (WAIS)-Working Memory Composite The domains of executive functions most frequently assessed are: cognitive flexibility, working memory, and inhibitory control/selective attention. Conclusion These findings offer valuable insights for future research directions and the development of standardized assessment protocols for executive functions, tailored to diverse socio-demographic profiles.

Mature neutrophils promote long-term functional recovery after spinal cord injury in a sex-dependent manner
Following spinal cord injury (SCI), neutrophils are the first peripheral immune cells to infiltrate the injured spinal cord in large numbers. There is a growing body of evidence demonstrating sex differences in neutrophil function, however, the role of sex as a biological variable in neutrophil response following SCI remain unclear. Additionally, while divergent roles for mature and immature neutrophil subsets have been observed, subset-specific contributions of neutrophils to functional recovery following SCI have not been fully characterized. Here, we provide novel evidence that systemic and localized neutrophil responses differ by sex following SCI. Antibody- mediated depletion of neutrophils following SCI revealed a previously unidentified role for mature neutrophils in promoting long-term functional recovery in a sex-dependent manner. We performed single-cell RNA sequencing analysis using publicly available datasets and discovered dramatic shifts in the phenotype of intraspinal neutrophils across time following SCI. We identified that mature neutrophils in the acutely injured spinal cord upregulate genes associated with resolution of inflammation. Furthermore, we found that depletion of mature neutrophils exacerbates long-term macrophage accumulation following SCI in a sex-dependent manner. Finally, we show that the beneficial properties of neutrophils in the injured spinal cord are temporally specific. Collectively, these data provide a first account of sex differences in the response of neutrophils to SCI. Our findings elucidate a novel and sex-dependent role for mature neutrophils in promoting resolution of inflammation and long-term recovery following SCI.

Extracellular vesicles aid in the transfer of long-term associative memory between Caenorhabditis elegans
Memory formation is necessary for the survival of animals across phyla. Here, we elucidate the mechanism underlying the formation of long-term associative memory (LTAM) formed by treating Caenorhabditis elegans with a volatile chemoattractant and heat. Previous work has shown that training animals with a paradigm involving heat and isoamyl alcohol (IAA) simultaneously, causes C. elegans to lose their attraction to IAA. In this study, we elaborate on the mechanism behind this LTAM formation and suggest that during training with heat and IAA, C. elegans release extracellular vesicles (EVs) that upon being taken up by the same trained animals or their untrained counterparts causes the organism to lose attraction to IAA. Our data suggests that the vesicles are highly specific to the training paradigms used and differ with differing cues. Finally, we show that this mechanism of transfer of LTAM appears to be conserved between C. elegans and C. briggsae allowing for both intra and interspecies transfer of memory.

Esr1-Dependent Signaling and Transcriptional Maturation in the Medial Preoptic Area of the Hypothalamus Shapes the Development of Mating Behavior during Adolescence
Mating and other behaviors emerge during adolescence through the coordinated actions of steroid hormone signaling throughout the nervous system and periphery. In this study, we investigated the transcriptional dynamics of the medial preoptic area (MPOA), a critical region for reproductive behavior, using single-cell RNA sequencing (scRNAseq) and in situ hybridization techniques in male and female mice throughout adolescence development. Our findings reveal that estrogen receptor 1 (Esr1) plays a pivotal role in the transcriptional maturation of GABAergic neurons within the MPOA during adolescence. Deletion of the estrogen receptor gene, Esr1, in GABAergic neurons (Vgat+) disrupted the developmental progression of mating behaviors in both sexes, while its deletion in glutamatergic neurons (Vglut2+) had no observable effect. In males and females, these neurons displayed distinct transcriptional trajectories, with hormone-dependent gene expression patterns emerging throughout adolescence and regulated by Esr1. Esr1 deletion in MPOA GABAergic neurons, prior to adolescence, arrested adolescent transcriptional progression of these cells and uncovered sex-specific gene-regulatory networks associated with Esr1 signaling. Our results underscore the critical role of Esr1 in orchestrating sex-specific transcriptional dynamics during adolescence, revealing gene regulatory networks implicated in the development of hypothalamic controlled reproductive behaviors.

One Sentence SummarySingle cell RNA sequencing reveals how adolescent sex hormones sculpt hypothalamic cell types required for mating behavior.

Reorganization of motor functions within visuomotor networks subsequent to somatosensory cortical damage
Somatosensory inputs are critical to motor control. Animal studies have shown that primary somatosensory lesions cause sensorimotor deficits along with disrupted organization in primary motor cortex (M1). How does damage in primary somatosensory cortex (S1) influence motor networks in humans? Using fMRI, we examined two individuals with extensive damage to left somatosensory cortex, but primarily intact motor cortex and preserved motor abilities. Given left S1 damage, tactile detection and localization were impaired for the contralesional hand in both individuals. When moving the contralesional hand, LS, with near complete damage to the S1 hand area, showed increased activation in ipsilesional putamen and deactivation in contralesional cerebellum relative to age-matched controls. These findings demonstrate influences of S1 damage to subcortical sensorimotor areas that are distant from the lesion site, and a potential reweighting of the motor network with increased action selection in putamen and inhibition of sensory prediction in cerebellum in the face of sensory loss. In contrast, RF, who had a small island of spared S1 in the hand area, showed greater activation in contralesional S1 for movement versus rest. This same region was also activated by pure somatosensory stimulation in a second experiment, suggesting that the spared S1 area in RF still subserves sensorimotor processing. Finally, the right middle occipital gyrus was more strongly activated in both individuals compared with controls, suggesting a potential reliance on visual imagery in the face of degraded sensory feedback.

Layer V Neocortical Neurons From Individuals With Drug-Resistant Epilepsy Show Multiple Synaptic Alterations but Lack Somatic Hyperexcitability
Although neuronal hyperexcitability is the primary mechanism underlying seizure activity in epilepsy, little is known about how different neuronal mechanisms at different organizational levels contribute to network hyperexcitability in the human epileptic brain. In this study, we determined a series of cellular and synaptic properties of layer V pyramidal neurons from neocortical tissue of patients with drug-resistant epilepsy that may contribute the hyperexcitable state associated with epilepsy. Using the whole cell, patch-clamp technique, and extracellular recordings, we determined the passive and active electrophysiological properties of layer V pyramidal neurons with regular spiking phenotypes from temporal, parietal, and frontal neocortices surgically resected from individuals with drug-resistant epilepsy. Also, the glutamatergic strength, the synchronicity between presynaptic volleys and field excitatory postsynaptic potentials, and short-term, frequency-dependent plasticity were determined at the synaptic level. Lastly, biocytin-filled pyramidal neurons were used to perform post hoc digital reconstructions and morphometric analyses. The collected data revealed that pyramidal neurons exhibit minimal spontaneous activity, similar resting membrane potentials, and input resistance values among the temporal, parietal, and frontal neocortices. Although frontal neurons were more hyperexcitable than temporal and parietal neurons, the firing output was comparable to that previously observed in non-pathological human tissue. The digital reconstructions confirmed the identity of pyramidal neurons and revealed alterations in dendritic complexity. In contrast, the analyses of the extracellular recordings uncovered significant desynchronization between presynaptic excitability and postsynaptic activity and loss of short-term depression in response to repetitive stimulation within the gamma range (30 Hz). Our data suggest that neocortical layer V pyramidal neurons from individuals with drug-resistant epilepsy are not necessarily hyperexcitable at the somatic level. Instead, synaptic alterations, such as synaptic desynchronization and a loss of frequency-dependent short-term depression may significantly contribute to the hyperexcitable state observed during seizure activity.

Most ventral pallidal cholinergic neurons are cortically projecting bursting basal forebrain cholinergic neurons
The ventral pallidum (VP) lies at the intersection of basal ganglia and basal forebrain circuitry, possessing attributes of both major subcortical systems. Basal forebrain cholinergic neurons are rapidly recruited by reinforcement feedback and project to cortical and subcortical forebrain targets; in contrast, striatal cholinergic cells are local interneurons exhibiting classical pause-burst responses to rewards. However, VP cholinergic neurons (VPCNs) are less characterized, and it is unclear whether basal forebrain and striatal type cholinergic neurons mix in the VP. Therefore, we performed anterograde and mono-transsynaptic retrograde labeling, in vitro acute slice recordings and bulk calcium recordings of VPCNs. We found that VPCNs broadly interact with the affective circuitry that processes rewards and punishments, targeting the basolateral amygdala, the nucleus accumbens, the medial prefrontal cortex and the lateral habenula, while receiving inputs from the nucleus accumbens, hypothalamus, central amygdala, bed nucleus of stria terminalis and the ventral tegmental area. Bulk calcium recordings revealed VPCN responses to rewards, punishments and reward-predicting cues, like those of the horizontal diagonal band of Broca of the basal forebrain. Acute slice recordings showed that most VPCNs resembled the bursting type of basal forebrain cholinergic neurons (BFCNs), while a few of them were of the regular rhythmic type, which sharply differentiated most VPCNs from striatal cholinergic interneurons. These results were confirmed by in vivo electrophysiological recordings of putative VPCNs largely resembling bursting BFCNs. We conclude that most VPCNs are BFCNs with specialized connectivity to relay aversive and appetitive stimuli to the reinforcement circuitry, possibly implicated in mood disorders and addiction.