bioRxiv Subject Collection: Neuroscience's Journal

Breathing modulates network activity in frontal brain regions during anxiety
Anxiety elicits various physiological responses, including changes in respiratory rate and neuronal activity within specific brain regions such as the medial prefrontal cortex (mPFC). Previous research suggests that the olfactory bulb (OB) modulates the mPFC through respiration-coupled neuronal oscillations (RCOs), which have been linked to fear-related freezing behavior. Nevertheless, the impact of breathing on frontal brain networks during other negative emotional responses, such as anxiety-related states characterized by higher breathing rates, remains unclear. To address this, we subjected rats to the elevated plus maze (EPM) paradigm while simultaneously recording respiration and local field potentials in the OB and mPFC. Our findings demonstrate distinct respiratory patterns during EPM exploration: slower breathing frequencies prevailed in the closed arms, whereas faster frequencies were observed in the open arms, independent of locomotor activity, indicating that anxiety-like states are associated with increased respiratory rates. Additionally, we identified RCOs at different frequencies, mirroring the bimodal distribution of respiratory frequencies. RCOs exhibited higher power during open arm exploration, when they showed greater coherence with breathing at faster frequencies. Furthermore, we confirmed that nasal respiration drives RCOs in frontal brain regions, and found a stronger effect during faster breathing. Interestingly, we observed that the frequency of prefrontal gamma oscillations modulated by respiration increased with heightened anxiety levels and breathing frequency. Overall, our study provides evidence for a significant influence of breathing on prefrontal cortex networks during anxious states, shedding light on the complex interplay between respiratory physiology and emotional processing.

Mapping Individual Differences in the Topological Landscape of Naturalistic Brain Dynamics
Naturalistic stimuli elicit rich subjective experiences through adaptive neural coordination. However, how inherent behavioral traits shape individual neural dynamics in naturalistic settings remains unclear. Here, we introduce a computational framework, STIM, to systematically capture individual differences in brain dynamics while watching diverse movie stimuli. By leveraging Topological Data Analysis, STIM generates a robust group-level dynamical landscape of brain latent states, mapping individual-specific divergence into global topology and local geometry. Applying STIM to large-sample movie fMRI datasets, we found that inter-individual variation in global topology exhibits a center-periphery gradient in the landscape. This gradient significantly explains individual fluid intelligence from a dual perspective, highlighting the importance of both adaptability and diversity of neural dynamics. At the fine-grained narrative level, individual local geometry attributes are associated with context-specific psychological traits beyond cognition. Furthermore, STIM reveals how the dynamical landscape evolves across neurodevelopment and exhibits abnormalities in psychiatric disorders such as autism. In summary, the STIM framework has the potential to transform rich naturalistic stimuli with brain recording into neural 'probes' to measure individual differences in cognition and mental health.

When your heart isn't in it anymore: Cardiac correlates of task disengagement
Neuroscience is beginning to uncover the role of interoceptive feedback in perception, learning, and decision-making; however, the relation between spontaneous visceral and cognitive dynamics has received surprisingly little scrutiny. Here, we investigate how subjective, physiological, and behavioural indicators of arousal and attentional state vary as a function of cardiac activity and brain-heart coupling. Combined electroencephalogram, electrocardiogram, and pupillometric records were obtained from 25 healthy human adults during the performance of a sustained attention to response task (SART). Thought-probes were intermittently administered during the SART to collect subjective reports of attentional state (i.e., on-task, mind-wandering, mind-blanking) and vigilance level (i.e., alertness). Mind-wandering and mind-blanking reports increased in frequency with time-on-task, but were associated with distinct behavioural profiles. Mind-blanking was further characterised by more profound decreases in heart-rate and pupil size than mind-wandering, and late modulation of the heartbeat-evoked potential. Besides attentional state, lower heart-rate predicted decreased vigilance and pupil size, while heart-rate variability predicted more impulsive behaviour and pupil dilation. Together, these findings reveal that cardiac parameters afford complementary information about arousal states and attentional dynamics, illustrating the complexity of task disengagement from a cognitive and physiological perspective.

Improving positively tuned voltage indicators for brightness and kinetics
The recent positively tuned ASAP4-family voltage indicators feature superior photostability compared to the negatively tuned ASAP3, but signal-to-noise ratios for spike detection were not significantly different. To improve spike detection by positively tuned ASAP indicators, we performed multiple rounds of structure-guided saturation mutagenesis of an ASAP4 template while screening directly for faster responses. Our resulting variants, ASAP6.1 and ASAP6b, demonstrated sufficient dynamic range and kinetics, and reported action potentials in vivo by one-photon and two-photon microscopy with high SNR and temporal resolution.

Piezo1 and Piezo2 channels in retinal ganglion cells and the impact of Piezo1 stimulation on light-dependent neural activity
Piezo channels are associated with neuropathology in diseases like traumatic brain injury and glaucoma, but pathways linking tissue stretch to aberrant neural signaling remain unclear. The present study demonstrates that Piezo1 activation increases action potential frequency in response to light and the spontaneous dark signal from mouse retinal explants. Piezo1 stimulation was sufficient to increase cytoplasmic Ca2+ in soma and neurites, while stretch increased spiking activity in current clamp recordings from of isolated retinal ganglion cells (RGCs). Axon-marker beta-tubulin III colocalized with both Piezo1 and Piezo2 protein in the mouse optic nerve head, while RGC nuclear marker BRN3A colocalized with Piezo channels in the soma. Piezo1 was also present on GFAP-positive regions in the optic nerve head and colocalized with glutamine synthetase in the nerve fiber layer, suggesting expression in optic nerve head astrocytes and Muller glia end feet, respectively. Human RGCs from induced pluripotent stem cells also expressed Piezo1 and Piezo2 in soma and axons, while staining patterns in rats resembled those in mice. mRNA message for Piezo1 was greatest in the RPE/choroid tissue, while Piezo2 levels were highest in the optic nerve, with both channels also expressed in the retina. Increased expression of Piezo1 and Piezo2 occurred both 1 and 10 days after a single stretch in vivo; this increase suggests a potential role in rising sensitivity to repeated nerve stretch. In summary, Piezo1 and Piezo2 were detected in the soma and axons of RGCs, and stimulation affected the light-dependent output of RGCs. The rise in RGCs excitability induced by Piezo stimulation may have parallels to the early disease progression in models of glaucoma and other retinal degenerations.

Using fingerprinting as a testbed for strategies to improve reproducibility of functional connectivity
Reproducible functional connectivity-based biomarkers have remained elusive despite the promise of deeply phenotyped consortia. An important component of reproducibility is reliability over repeated measures, often measured by the intraclass correlation coefficient (ICC). Here, we test the use of functional connectome fingerprinting as a way to select pre- and post-processing parameters. We hypothesized that whichever parameters yielded the best fingerprint accuracies would also improve the ICC across scans. Using five datasets from the Consortium for Replicability and Reproducibility, we found that higher identification accuracies were achieved when using: (I) global signal regression; (II) finer brain parcellations; (III) cortical regions compared to subcortical and cerebellar structures; (IV) medial frontal and frontoparietal networks relative to the whole-brain; (V) discriminative edges; (VI) longer scan duration; and (VII) lower sample size. We observed that the ICC was consistently "poor" across the five datasets even with the application of two optimal fingerprint-informed pipelines. The fingerprint-informed pipelines may enable comparison, benchmarking, and adjudication of functional connectivity-based analysis pipelines or novel analytic approaches, as a means to enhance their reproducibility in heterogeneous populations.

Aberrant TSC-Rheb axis in Oxytocin receptor+ cells mediate stress-induced anxiety
Stress is a major risk for the onset of several maladaptive processes including pathological anxiety, a diffuse state of heightened apprehension over anticipated threats1. Pathological anxiety is prevalent in up to 59% of patients with Tuberous Sclerosis complex (TSC)2, a neurodevelopmental disorder (NDD) caused by loss-of-function mutations in genes for Tuberin (Tsc2) and/or Hamartin (Tsc1) that together comprise the eponymous protein complex. Here, we generated cell type-specific heterozygous knockout of Tsc2 in cells expressing oxytocin receptor (OTRCs) to model pathological anxiety-like behaviors observed in TSC patient population. The stress of prolonged social isolation induces a sustained negative affective state that precipitates behavioral avoidance, often by aberrant oxytocin signaling in the limbic forebrain3,4. In response to social isolation, there were striking sex differences in stress susceptibility in conditional heterozygote mice when encountering situations of approach-avoidance conflict. Socially isolated male mutants exhibited behavioral avoidance in anxiogenic environments and sought more social interaction for buffering of stress. In contrast, female mutants developed resilience during social isolation and approached anxiogenic environments, while devaluing social interaction. Systemic and medial prefrontal cortex (mPFC)-specific inhibition of downstream effector of TSC, the integrated stress response (ISR), rescued behavioral approach toward anxiogenic environments and conspecifics in male and female mutant mice respectively. Further, we found that Tsc2 deletion in OTRCs leads to OTR-signaling elicited network suppression, i.e., hypofrontality, in male mPFC, which is relieved by inhibiting the ISR. Our findings present evidence in support of a sexually dimorphic role of prefrontal OTRCs in regulating emotional responses in anxiogenic environments, which goes awry in TSC. Our work has broader implications for developing effective treatments for subtypes of anxiety disorders that are characterized by cell-autonomous ISR and prefrontal network suppression.

Weakly nonlinear responses at low intrinsic noise levels in two types of electrosensory primary afferents
Neuronal processing is inherently nonlinear -spiking thresholds or rectification in synapses are central to neuronal computations. Nevertheless, linear response theory has been instrumental in understanding, for example, the impact of noise or synchronous spikes on signal transmission, or the emergence of oscillatory activity. At higher signal-to-noise ratios, however, the third term in the Volterra series becomes relevant. This second-order susceptibility captures nonlinear interactions between pairs of stimulus frequencies. Theoretical results for leaky integrate-and-fire neurons suggest strong responses at the sum of two input frequencies only when these frequencies or their sum match the neuron's baseline firing rate. We here analyze second-order susceptibilities in two types of primary electroreceptor afferents, P-units of the active and ampullary cells of the passive electrosensory system of the wave-type electric fish Apteronotus leptorhynchus. In our combined experimental and modeling approach we find the predicted weakly nonlinear responses in some P-units with very low baseline interspike-interval variability and much stronger in all ampullary cells, which are less noisy than P-units. Such nonlinear responses boost responses to weak sinusoidal stimuli and are therefore of immediate relevance for wave-type electric fish that are exposed to superpositions of many frequencies in social contexts.

Myo-optogenetics: optogenetic stimulation and electrical recording in skeletal muscles
Complex movements involve highly coordinated control of local muscle elements. Highly controlled perturbations of motor outputs can reveal insights into the neural control of movements. Here we introduce an optogenetic method, compatible with electromyography (EMG) recordings, to perturb muscles in transgenic mice. By expressing channelrhodopsin in muscle fibers, we achieved noninvasive, focal activation of orofacial muscles, enabling detailed examination of the mechanical properties of optogenetically evoked jaw muscle contractions. We demonstrated simultaneous EMG recording and optical stimulation, revealing the electrophysiological characteristics of optogenetically triggered muscle activity. Additionally, we applied optogenetic activation of muscles in physiologically and behaviorally relevant settings, mapping precise muscle actions and perturbing active behaviors. Our findings highlight the potential of muscle optogenetics to precisely manipulate muscle activity, offering a powerful tool for probing neuromuscular control systems and advancing our understanding of motor control.

RNAi-mediated silencing of SOD1 profoundly extends survival and functional outcomes in ALS mice
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative condition, with 20% of familial and 2-3% of sporadic cases linked to mutations in the cytosolic superoxide dismutase (SOD1) gene. Mutant SOD1 protein is toxic to motor neurons, making SOD1 gene lowering a promising approach, supported by preclinical data and the 2023 FDA approval of the GapmeR ASO targeting SOD1, tofersen. Despite the approval of an ASO and the optimism it brings to the field, the pharmacodynamics and pharmacokinetics of therapeutic SOD1 modulation can be improved. Here, we developed a chemically stabilized divalent siRNA scaffold (di-siRNA) that effectively suppresses SOD1 expression in vitro and in vivo. With optimized chemical modification, it achieves remarkable CNS tissue permeation and SOD1 silencing in vivo. Administered intraventricularly, di-siRNASOD1 extended survival in SOD1-G93A ALS mice, surpassing survival previously seen in these mice by ASO modalities, slowed disease progression, and prevented ALS neuropathology. These properties offer an improved therapeutic strategy for SOD1-mediated ALS and may extend to other dominantly inherited neurological disorders.

One sentence summarySilencing SOD1 with chemically optimized divalent siRNA profoundly extends the lifespan of G93A mice and prevents neurodegenerative biochemical and behavioral phenotypes.

MICROENDOSCOPIC CALCIUM IMAGING IN SUPPLEMENTARY MOTOR AREA AND PRIMARY MOTOR CORTEX OF RHESUS MACAQUES AT REST AND DURING ARM MOVEMENT
The motor cortical regions have undergone evolutionary expansion and specialization from rodents to primates. Therefore, the study of these regions in non-human primates (NHPs) is relevant to understand motor control in healthy conditions or in NHP models of movement disorders. The use of calcium imaging and miniature microscopes allows the study of multiple individual neurons in cortical regions. We used this method to examine the activities of supplementary motor area (SMA) and primary motor region (M1) in four rhesus macaques. We implanted gradient index (GRIN) lenses and expressed GCaMP6f in cortical projection neurons in these regions and imaged calcium transients for weeks to months while the animals were at rest (spontaneous or idle condition) or engaged in a simple arm reaching task. We found that in a proportion of cells, in both cortical regions, the calcium activity was directionally tuned during the arm reaching task, in agreement with previous electrophysiological findings. We identified pairs of cells, scattered across the imaging fields in SMA and M1, with synchronous activity. Finally, we found that neurons in SMA and M1 have calcium transients that occur in precisely timed sequences, and that the sequences and neuronal ensembles participating in the sequences are dynamic. The microendoscopic calcium imaging technique can be used to examine calcium dynamics in groups of corticofugal neurons in SMA and M1 and compare patterns of activity among cells.

α/β-Hydrolase domain-containing 6 (ABHD6) accelerates the desensitization and deactivation of TARP γ-2-containing AMPA receptors
AMPA receptors (AMPARs) mediate most of the fast excitatory synaptic transmission in mammalian brain. Their efficacy in responding to presynaptic glutamate release depends on their kinetics, which are determined by AMPARs and their auxiliary subunit composition. /{beta}-Hydrolase domain-containing 6 (ABHD6) is an AMPAR auxiliary subunit that has been shown to negatively regulate the surface delivery of AMPARs and AMPAR-mediated currents. Overexpression of ABHD6 decreased the rising slope and increased the decay {tau} of mEPSCs. However, whether ABHD6 is involved in regulating AMPAR kinetics remains unclear. Here, we found that ABHD6 per se had no effects on the gating kinetics of GluA1 and GluA2(Q) containing homomeric receptors. However, in the presence of the auxiliary subunit TARP {gamma}-2, ABHD6 accelerated the deactivation and desensitization of either GluA1 and GluA2(Q) containing homomeric receptors independent of their splicing isoforms (flip and flop) and the editing isoforms of GluA2 (R or G at position 764), except the deactivation of GluA2(Q)i-G isoform. Besides, the recovery from desensitization of GluA1 with flip splicing isoform was slowed by the co-expression of ABHD6 in the presence of TARP {gamma}-2. Furthermore, the ABHD6 accelerated the deactivation and desensitization of GluA1i/GluA2(R)i-G heteromeric receptors in the presence of TARP {gamma}-2. Therefore, these results demonstrate that ABHD6 regulates AMPAR gating kinetics in a TARP {gamma}-2-dependent manner.

SIGNIFICANCE STATEMENTThe efficacy of AMPARs in responding to presynaptic glutamate release depends on their kinetics, including deactivation, desensitization, and recovery from desensitization, which are determined by AMPARs and their auxiliary subunit composition. Using ultra-fast application of glutamate and outside-out patch recordings, we found that, in the presence of the auxiliary subunit TARP {gamma}-2, ABHD6 accelerated the deactivation and desensitization of GluA1i/GluA2(R)i-G heteromeric receptors and GluA1 and GluA2(Q) containing homomeric receptors independent of their splicing isoforms (flip and flop) and the editing isoforms of GluA2 (R or G at position 764), except the deactivation of GluA2(Q)i-G isoform. These results demonstrate that ABHD6 regulates AMPAR gating kinetics in a TARP {gamma}-2-dependent manner.

Central tendency and serial dependence in vestibular path integration
Path integration, the process of updating one's position using successive self-motion signals, has previously been studied using visual distance reproduction tasks in which optic flow patterns provide information about traveled distance. These studies have reported that reproduced distances show two types of systematic biases: central tendency and serial dependence. In the present study, we investigated whether these biases are also present in vestibular path integration. Participants were seated on a linear motion platform and performed a distance reproduction task in total darkness. The platform first passively moved the participant a pre-defined stimulus distance which they then actively reproduced by steering the platform back the same distance. Stimulus distances were sampled from short- and long-distance probability distributions and presented in either a randomized order or in separate blocks to study the effect of presentation context. Similar to the effects observed in visual path integration, we found that reproduced distances showed an overall positive central tendency effect as well as a positive, attractive serial dependence effect. Furthermore, reproduction behavior was affected by presentation context. These results were mostly consistent with predictions of a Bayesian Kalman-filter model, originally proposed for visual path integration.

An in vivo genetic screen identifies Crq as a potent glial regulator of synapse elimination in development and aging
Neurons and glia work together to regulate neural circuit assembly and maintenance, but our understanding of how remains superficial. In this study, we establish that Drosophila exhibit large-scale synapse formation and elimination as part of circuit maturation, and that glia use conserved molecules to regulate these processes. We used a high throughput ELISA-based screening assay to identify new glial genes that regulate synapse numbers in Drosophila in vivo, including the scavenger receptor ortholog Croquemort (Crq). We found that Crq acts as an essential regulator of glial-dependent synapse elimination during development, leading to excess synapses and progressive seizure susceptibility in flies which lack Crq expression in glia. Loss of Crq in glia also prevents age-related synaptic loss. This work provides a platform to gain insight into the cellular and molecular mechanisms that underlie synapse development and maintenance across the lifespan, and identifies glial Crq as a key regulator of these processes.

Slow and steady: auditory features for discriminating animal vocalizations
We propose that listeners can use temporal regularities - spectro-temporal correlations that change smoothly over time - to discriminate animal vocalizations within and between species. To test this idea, we used Slow Feature Analysis (SFA) to find the most temporally regular components of vocalizations from birds (blue jay, house finch, American yellow warbler, and great blue heron), humans (English speakers), and rhesus macaques. We projected vocalizations into the learned feature space and tested intra-class (same speaker/species) and inter-class (different speakers/species) auditory discrimination by a trained classifier. We found that: 1) Vocalization discrimination was excellent (> 95%) in all cases; 2) Performance depended primarily on the [~]10 most temporally regular features; 3) Most vocalizations are dominated by [~]10 features with high temporal regularity; and 4) These regular features are highly correlated with the most predictable components of animal sounds.

Integrating episodic and spatial context signals in the hippocampus
Episodic and spatial memory are the two key components of the mnemonic system in humans. Episodic memory enables us to remember events from the past whereas spatial memory enables us to form a map-like representation of the environment. Interestingly, these seemingly different functions rely on the same brain structure: the hippocampus. Yet, how the hippocampus supports both at the same time remains unclear. Here, we tested the hypotheses that the hippocampus supports these two systems either via a common coding mechanism or via a parallel processing mechanism. To this end, we combined functional magnetic resonance imaging (fMRI) with an episodic life-simulation task and a spatial virtual reality task to manipulate episodic and spatial context associations of objects. We then investigated fMRI adaptation effects between these objects as a result of shared contexts. We found that the fMRI signal in the anterior hippocampus scaled with the combined prediction of shared episodic and spatial contexts, in line with the idea of a common coding mechanism. We found no evidence for a parallel processing mechanism, as there were no differences between episodic and spatial effects. The common coding effect for episodic and spatial memory dovetails with the broader notion of domain-general hippocampal cognitive maps.

Presynaptic GABAA receptors control integration of nicotinic input onto dopaminergic axons in the striatum
Axons of dopaminergic neurons express gamma-aminobutyric acid type-A receptors (GABAARs) and nicotinic acetylcholine receptors (nAChRs) which are both independently positioned to shape striatal dopamine release. Using electrophysiology and calcium imaging, we investigated how interactions between GABAARs and nAChRs influence dopaminergic axon excitability. Direct axonal recordings showed that benzodiazepine application suppresses subthreshold axonal input from cholinergic interneurons (CINs). In imaging experiments, we used the first temporal derivative of presynaptic calcium signals to distinguish between direct- and nAChR-evoked activity in dopaminergic axons. We found that GABAAR antagonism with gabazine selectively enhanced nAChR-evoked axonal signals. Acetylcholine release was unchanged in gabazine suggesting that GABAARs located on dopaminergic axons, but not CINs, mediated this enhancement. Unexpectedly, we found that a widely used GABAAR antagonist, picrotoxin, inhibits axonal nAChRs and should be used cautiously for striatal circuit analysis. Overall, we demonstrate that GABAARs on dopaminergic axons regulate integration of nicotinic input to shape presynaptic excitability.

Cortical Processing of Conspecific Vocalizations in Zebra Finches Depends on the Early Acoustical Environment
Sensory experience during development has lasting effects on perception and neural processing. Exposing animals to artificial stimuli early in life influences the tuning and functional organization of the auditory cortex, but less is known about how the rich acoustical environments experienced by vocal communicators affect the processing of complex vocalizations. Here, we show that in zebra finches (Taeniopygia guttata), a colonial-breeding songbird species, exposure to a naturalistic social-acoustical environment during development has a profound impact on cortical-level auditory responses to conspecific song. Compared to birds raised by pairs in acoustic isolation, birds raised in a breeding colony had higher average firing rates, selectivity, and discriminability, especially in the narrow-spiking, putatively inhibitory neurons of a higher-order auditory area, the caudomedial nidopallium (NCM). Neurons in colony-reared birds were also less correlated in their tuning and more efficient at encoding the spectrotemporal structure of conspecific song. These results suggest that the auditory cortex adapts to noisy, complex acoustical environments by strengthening inhibitory circuitry, functionally decoupling excitatory neurons while maintaining overall excitatory-inhibitory balance.

Separating sensory from timing processes: a cognitive encoding and neural decoding approach
The internal clock is a psychological model for timing behavior. According to information theory, psychological time might be a manifestation of information flow during sensory processing. Herein, we tested three hypotheses: (1) whether sensory adaptation reduces (or novelty increases) the rate of the internal clock (2) whether the speed of the clock reflects the amount of cortical sensory processing? (3) whether motion tunes clock speed.

The current study used an oddball paradigm in which participants detected duration changes while being recorded with electroencephalography (EEG). For data analysis, we combined cognitive modeling with neural decoding techniques. Specifically, we designed Adaptive-Thought-of-Control (ACT-R) models to explain human data and linked them to the sensory EEG features discovered through machine learning.

Our results indicate that timing performance is influenced by both timing and non-timing factors. The internal clock may reflect the amount of sensory processing, thereby clarifying a long-standing sensory timing mystery.

Pronouns reactivate conceptual representations in human hippocampal neurons
During discourse comprehension, every new word adds to an evolving representation of meaning that accumulates over consecutive sentences and constrains the next words. To minimize repetition and utterance length, languages use pronouns, like the word she, to refer to nouns and phrases that were previously introduced. It has been suggested that language comprehension requires that pronouns activate the same neuronal representations as the nouns themselves. Here, we test this hypothesis by recording from individual neurons in the human hippocampus during a reading task. We found that cells that are selective to a particular noun are later reactivated by pronouns that refer to the cells preferred noun. These results imply that concept cells contribute to a rapid and dynamic semantic memory network which is recruited during language comprehension. This study uniquely demonstrates, at the single-cell level, how memory and language are linked.

Sex-steroid hormones relate to cerebellar structure and functional connectivity across adulthood
Aging involves complex biological changes that affect disease susceptibility and aging trajectories. Although females typically live longer than males, they have a higher susceptibility to diseases like Alzheimers, speculated to be influenced by menopause, and reduced ovarian hormone production. Understanding sex-specific differences is crucial for personalized medical interventions and gender equality in health. Our study aims to elucidate sex differences in regional cerebellar structure and connectivity during normal aging by investigating both structural and functional connectivity variations, with a focus on investigating these differences in the context of sex-steroid hormones. The study included 138 participants (mean age = 57(13.3) years, age range = 35-86 years, 54% women). The cohort was divided into three groups: 38 early middle-aged individuals (EMA) (mean age = 41(4.7) years), 48 late middle-aged individuals (LMA) (mean age = 58(4) years), and 42 older adults (OA) (mean age = 72(6.3) years). All participants underwent MRI scans, and saliva samples were collected for sex-steroid hormone quantification (17{beta}-estradiol (E), progesterone (P), and testosterone (T)). We found less connectivity in females between Lobule I-IV and the cuneus, and greater connectivity in females between Crus I, Crus II, and the precuneus with increased age. Higher 17{beta}-estradiol levels were linked to greater connectivity in Crus I and Crus II cerebellar subregions. Analyzing all participants together, testosterone was associated with both higher and lower connectivity in Lobule I-IV and Crus I, respectively, while higher progesterone levels were linked to lower connectivity in females. Structural differences were observed, with EMA males having larger volumes compared to LMA and OA groups, particularly in the right I-IV, right Crus I, right V, and right VI. EMA females showed higher volumes in the right lobules V and VI. These results highlight the significant role of sex hormones in modulating cerebellar connectivity and structure across adulthood, emphasizing the need to consider sex and hormonal status in neuroimaging studies to better understand age-related cognitive decline and neurological disorders.

Thalamocortical contributions to hierarchical cognitive control
Cognitive flexibility relies on hierarchically structured task representations that organize task contexts, relevant environmental features, and subordinate decisions. Despite ongoing interest in the human thalamus, its role in cognitive control has been understudied. This study explored thalamic representation and thalamocortical interactions that contribute to hierarchical cognitive control in humans. We found that several thalamic nuclei, including the anterior, mediodorsal, ventrolateral, and pulvinar nuclei, exhibited stronger evoked responses when subjects switch between task contexts. Decoding analysis revealed that thalamic activity preferentially encodes task contexts within the hierarchical task representations. To determine how thalamocortical interactions contribute to task representations, we developed a thalamocortical functional interaction model to predict task-related cortical representation. This data-driven model outperformed comparison models, particularly in predicting activity patterns in cortical regions that encode context representations. Collectively, our findings highlight the significant contribution of thalamic activity and thalamocortical interactions for contextually guided hierarchical cognitive control.

Astrocytic glutamate regulation is implicated in the development of stress-related psychiatric disorders
Severe psychological stress is one of the most potent risk factors for developing a mood or psychotic disorder, yet the underlying molecular mechanisms are poorly understood. Astrocytes are a key brain cell type associated with stress and psychiatric phenotypes in animals, but how this translates to humans is largely unknown. Here, we show that cortical astrocytes are persistently changed both physically and molecularly in humans with psychiatric disorders exposed to profound stress before diagnosis. By profiling the diversity of human astrocytes with single nucleus and spatial transcriptomics, we identified distinct alterations to glutamate-related synaptic functions, supported by histological quantification of >20,000 astrocytes. Alterations were pronounced in females compared to males and in cases exposed to profound stress during childhood. The use of human pluripotent stem cell-derived astrocytes confirmed that glutamate signalling is directly impacted by glucocorticoid activation. Our findings suggest that astrocytes are strategic pharmacological targets for future intervention strategies.

The Alzheimer's disease gene SORL1 regulates lysosome function in human microglia
The SORL1 gene encodes the sortilin related receptor protein SORLA, a sorting receptor that regulates endo-lysosomal trafficking of various substrates. Loss of function variants in SORL1 are causative for Alzheimers disease (AD) and decreased expression of SORLA has been repeatedly observed in human AD brains. SORL1 is highly expressed by microglia, the tissue resident immune cells of the brain. Loss of SORLA leads to enlarged lysosomes in hiPSC-derived microglia like cells (hMGLs). However, whether SORLA deficiency contributes to microglia dysfunction and how this is relevant to AD is not known. In this study, we show that loss of SORLA results in decreased lysosomal degradation and lysosomal enzyme activity due to altered trafficking of lysosomal enzymes in hMGLs. Furthermore, lysosomal exocytosis, an important process involved in immune responses and cellular signaling, is also impaired in SORL1 deficient microglia. Phagocytic uptake of fibrillar amyloid beta 1-42 and synaptosomes is increased in SORLA deficient hMGLs, but due to reduced lysosomal degradation, these substrates aberrantly accumulate in lysosomes. Overall, these data highlight the microglial endo-lysosomal network as a potential novel pathway through which SORL1 may increase AD risk and contribute to development of AD. Additionally, our findings may inform development of novel lysosome and microglia associated drug targets for AD.

AAV delivery of GBA1 suppresses alpha-synuclein accumulation in Parkinson's disease models and restores motor dysfunction in a Gaucher's disease model
Biallelic mutations in the glucosylceramidase beta 1 (GBA1) gene are the underlying genetic cause of Gaucher's disease (GD), resulting in a deficient lysosomal hydrolase and subsequent accumulation of glycosphingolipids. More recently, GBA1 mutations have been identified as the most prevalent genetic risk factor for Parkinson's disease (PD), associated with more pronounced symptoms characterized by earlier onset and accelerated cognitive decline. In these GBA-associated PD patients the alpha-synuclein pathology is more prominent, and recent data suggest a link between alpha-synucleinopathies and GBA1 mutations. Here, we explored the effect of GBA1 gene supplementation on the GD phenotypes and alpha-synuclein pathology by using the adeno-associated virus (AAV) system. We have compared two AAV serotypes, AAV5 and AAV9, and two different ubiquitous promoters, and demonstrate that both promoters work efficiently albeit not the same in vitro and in vivo. GBA1 overexpression reduces the accumulation of glucosylsphingosine (GlcSph) and restores motor dysfunction in a GD mouse model. We further demonstrate that GBA1 overexpression can dissolve phospho-alpha-synuclein aggregation induced by the addition of alpha-synuclein pre-formed fibril (PFF) in a mouse primary neuron model suggesting the direct effect of beta-Glucocerebrosidase (GCase) on alpha-synuclein accumulation. In vivo, we show that GCase inhibition can induce insoluble high-molecular-weight alpha-synuclein aggregation and that delivery of GBA1 achieves robust reduction of the alpha-synuclein aggregates in the mouse brain. In summary, GCase expression not only reduces GlcSph, but also restores GD motor dysfunction and removes alpha-synuclein aggregates which are the hallmark for PD and alpha-synucleinopathies. AAV delivery of GBA1 is a powerful approach to restore glucocerebrosidase function and to resolve misfolded alpha-synuclein protein, with applications for GD and PD.

Heteromeric amyloid filaments of ANXA11 and TDP-43 in FTLD-TDP Type C
Neurodegenerative diseases are characterised by the abnormal filamentous assembly of specific proteins in the central nervous system. Human genetic studies established a causal role for protein assembly in neurodegeneration. However, the underlying molecular mechanisms remain largely unknown, which is limiting progress in developing clinical tools for these diseases. Recent advances in electron cryo-microscopy (cryo-EM) have enabled the structures of the protein filaments to be determined from patient brains1. All diseases studied to date have been characterised by the self-assembly of a single intracellular protein in homomeric amyloid filaments, including that of TAR DNA-binding protein 43 (TDP-43) in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration with TDP-43 inclusions (FTLD-TDP) Types A and B. Here, we used cryo-EM to determine filament structures from the brains of individuals with FTLD-TDP Type C, one of the most common forms of sporadic FTLD-TDP. Unexpectedly, the structures revealed that a second protein, annexin A11 (ANXA11), co-assembles with TDP-43 in heteromeric amyloid filaments. The ordered filament fold is formed by TDP-43 residues G282/284-N345 and ANXA11 residues L39-L74 from their respective low-complexity domains (LCDs). Regions of TDP-43 and ANXA11 previously implicated in protein-protein interactions form an extensive hydrophobic interface at the centre of the filament fold. Immunoblots of the filaments revealed that the majority of ANXA11 exists as a ~22 kDa N-terminal fragment (NTF) lacking the annexin core domain. Immunohistochemistry of brain sections confirmed the co-localisation of ANXA11 and TDP-43 in inclusions, redefining the histopathology of FTLD-TDP Type C. This work establishes a central role for ANXA11 in FTLD-TDP Type C. The unprecedented formation of heteromeric amyloid filaments in human brain revises our understanding of amyloid assembly and may be of significance for the pathogenesis of neurodegenerative diseases.

A single-cell transcriptomic atlas of sensory-dependent gene expression in developing mouse visual cortex
Sensory experience drives the refinement and maturation of neural circuits during postnatal brain development through molecular mechanisms that remain to be fully elucidated. One likely mechanism involves the sensory-dependent expression of genes that encode direct mediators of circuit remodeling within developing cells. However, while studies in adult systems have begun to uncover crucial roles for sensory-induced genes in modifying circuit connectivity, the gene programs induced by brain cells in response to sensory experience during development remain to be fully characterized. Here, we present a single-nucleus RNA-sequencing dataset describing the transcriptional responses of cells in mouse visual cortex to sensory deprivation or sensory stimulation during a developmental window when visual input is necessary for circuit refinement. We sequenced 118,529 individual nuclei across sixteen neuronal and non-neuronal cortical cell types isolated from control, sensory deprived, and sensory stimulated mice, identifying 1,268 unique sensory-induced genes within the developing brain. To demonstrate the utility of this resource, we compared the architecture and ontology of sensory-induced gene programs between cell types, annotated transcriptional induction and repression events based upon RNA velocity, and discovered Neurexin and Neuregulin signaling networks that underlie cell-cell interactions via CellChat. We find that excitatory neurons, especially layer 2/3 pyramidal neurons, are highly sensitive to sensory stimulation, and that the sensory-induced genes in these cells are poised to strengthen synapse-to-nucleus crosstalk by heightening protein serine/threonine kinase activity. Altogether, we expect this dataset to significantly broaden our understanding of the molecular mechanisms through which sensory experience shapes neural circuit wiring in the developing brain.

CD11c-expressing microglia are transient, driven by interactions with apoptotic cells
Microglia, the parenchymal macrophage of the central nervous system serve crucial remodeling functions throughout development. Microglia are transcriptionally heterogenous, suggesting that distinct microglial states confer discrete roles. Currently, little is known about how dynamic these states are, the cues that promote them, or how they impact microglial function. In the developing retina, we previously found a significant proportion of microglia express CD11c (Integrin X, complement receptor 4, Itgax) which has also been reported in other developmental and disease contexts. Here, we sought to understand the regulation and function of CD11c+ microglia. We found that CD11c+ microglia track with prominent waves of neuronal apoptosis in postnatal retina. Using genetic fate mapping, we provide evidence that microglia transition out of the CD11c state to return to homeostasis. We show that CD11c+ microglia have elevated lysosomal content and contribute to the clearance of apoptotic neurons, and found that acquisition of CD11c expression is, in part, dependent upon the TAM receptor Axl. Using selective ablation, we found CD11c+ microglia are not uniquely critical for phagocytic clearance of apoptotic cells. Together, our data suggest CD11c+ microglia are a transient state induced by developmental apoptosis rather than a specialized subset mediating phagocytic elimination.

Visual search efficiency is modulated by symmetry type and texture regularity
More than a century of vision research has identified symmetry as a fundamental cue, which aids the visual system in making inferences about objects and surfaces in natural scenes. Most studies have focused on one type of symmetry, reflection, presented at a single image location. However, the visual system responds strongly to other types of symmetries, and to symmetries that are repeated across the image plane to form textures. Here we use a visual search paradigm with arrays of repeating lattices that contained either reflection or rotation symmetries but were otherwise matched. Participants were asked to report the presence of a target tile without symmetry. When lattices tile the plane without gaps, they form regular textures. We manipulated texture regularity by introducing jittered gaps between lattices. This paradigm lets us investigate the effect of symmetry type and texture regularity on visual search efficiency. Based on previous findings suggesting an advantage for reflection in visual processing, we hypothesized that search would be more efficient for reflection than rotation. We further hypothesized that regular textures would be processed more efficiently. We found independent effects of symmetry type and regularity on search efficiency that confirmed both hypotheses: visual search was more efficient for textures with reflection symmetry and more efficient for regular textures. This provides additional support for the perceptual advantage of reflection in the context of visual search and provides important new evidence in favor of visual mechanisms specialized for processing symmetries in regular textures.

Total neuroelectric brain activity derived from resting-state MEG is invariable across the adult lifespan
Ageing of the human brain was studied using large array of experimental data. The magnetic encephalograms and magnetic resonance images of the head were obtained from the open archive CamCAN. Bad data were rejected, then functional tomograms were found - the spatial distribution of elementary spectral components. Physiological noise was eliminated by joint analysis of the functional tomograms and magnetic resonance images. By massively solving the inverse problem, multichannel spectra were transformed into time series of the power of elementary current dipoles. Age-related changes in the electrical power of various brain rhythms were examined. It was found that the summary electrical activity of the brain is constant throughout a persons life. The electric power is redistributed during the lifetime: delta rhythm is diminishing, giving slow rise to all other rhythms.

Single-nucleus RNA sequencing of striatal microglia reveals distinct transcriptomic signatures of acute stress and chronic exercise
Severe acute stress can produce long lasting decreases in voluntary physical activity that contribute to degraded mental and physical health. Stress also produces enduring molecular changes in the striatum, a brain region that regulates voluntary wheel-running and other motivated behaviors. Microglia, the primary immune cells of the central nervous system, have specialized functions in responding to stress, sensing changes in the striatum, and controlling neuronal activity. Thus, microglia are positioned at the interface between neural responses to stress and neural coordination of voluntary activity; however, the role of striatal microglia in stress-induced long-term suppression of voluntary activity remains unexplored. The present study employs single nucleus RNA-sequencing to investigate how stress and exercise impact the biology of microglia in the striatum. We find that stress-induced decreases in running behavior are associated with specific microglial activation profiles. Furthermore, we show that access to a running wheel is associated with an additional and distinct profile of microglia activation characterized by upregulation of complement components and phagocytosis pathways. Lastly, we find that distinct microglial gene sets are associated with general running (versus not running) and more subtle variation in genes with individual running levels. Taken together, our results contribute to a broader understanding of the diverse states that striatal microglia can assume in response to stress and exercise, and broadly suggest that microglia exhibit more nuanced functional responses to environmental perturbations than previously thought.

Retinal microglial cells increase expression and release of IL-1β when exposed to ATP
Cytokine IL-1{beta} is an early component of inflammatory cascades, with both priming and activation steps required before IL-1{beta} release. Here, the P2X7 receptor (P2X7R) for ATP was shown to both prime and release IL-1{beta} from retinal microglial cells. Isolated retinal microglial cells increased expression of Il1b when stimulated with endogenous receptor agonist extracellular ATP; ATP also rapidly downregulated expression of microglial markers Tmem119 and Cd206. Changes to all three genes were reduced by specific P2X7R antagonist A839977, implicating the P2X7R. Microglial cells expressed the P2X7R on ramifications and responded to receptor agonist BzATP with robust and rapid rises in intracellular Ca2+. BzATP increased expression of IL-1{beta} protein colocalizing with CX3CR1-GFP in retinal wholemounts consistent with microglial cells. ATP also triggered release of IL-1{beta} from isolated retinal microglia into the bath; release was inhibited by A839977 and induced by BzATP, supporting a role for the P2X7R in release as well as priming. The IL-1{beta} release triggered by ATP was substantially greater from microglial cells compared to astrocytes from the optic nerve head region. Il1b expression was increased by a transient rise in intraocular pressure and Il1b levels remained elevated 10 days after a single IOP elevation. In summary, this study suggests the P2X7 receptor can both prime IL-1{beta} levels in microglial cells and trigger its release. The P2Y12R was previously identified as a chemoattractant for retinal microglia, suggesting the recruitment of the cells towards the source of released extracellular ATP could position microglia for P2X7R receptor, enabling both priming and release of IL-1{beta}.

Dopamine increases protein synthesis in hippocampal neurons enabling dopamine-dependent LTP
The reward and novelty related neuromodulator dopamine plays an important role in hippocampal long-term memory, which is thought to involve protein synthesis-dependent synaptic plasticity. However, the direct effects of dopamine on protein synthesis, and the functional implications of newly synthesized proteins for synaptic plasticity, have not yet been investigated. We have previously reported that timing-dependent synaptic depression (t-LTD) can be converted into potentiation by dopamine application during synaptic stimulation (Brzsoko et al., 2015) or postsynaptic burst activation (Fuchsberger et al., 2022). Here we show that dopamine increases protein synthesis in mouse hippocampal CA1 neurons, enabling dopamine-dependent long-term potentiation (DA-LTP). We found that neuronal activity is required for the dopamine-induced increase in protein synthesis, which is mediated via the Ca2+-sensitive adenylate cyclase (AC) subtypes 1/8, cAMP, and cAMP-dependent protein kinase (PKA). Furthermore, dopamine induced a protein synthesis-dependent increase in the AMPA receptor subunit GluA1, but not GluA2. We found that DA-LTP is absent in GluA1 knock-out mice and that it requires calcium-permeable AMPA receptors. Taken together, our results suggest that dopamine together with neuronal activity controls synthesis of plasticity-related proteins, including GluA1, which enable DA-LTP via a signalling pathway distinct from that of conventional LTP.

Multi-talker speech comprehension at different temporal scales in listeners with normal and impaired hearing
Comprehending speech requires deciphering a range of linguistic representations, from phonemes to narratives. Prior research suggests that in single-talker scenarios, the neural encoding of linguistic units follows a hierarchy of increasing temporal receptive windows. Shorter temporal units like phonemes and syllables are encoded by lower-level sensory brain regions, whereas longer units such as sentences and paragraphs are processed by higher-level perceptual and cognitive areas. However, the brains representation of these linguistic units under challenging listening conditions, such as a cocktail party situation, remains unclear. In this study, we recorded electroencephalogram (EEG) responses from both normal-hearing and hearing-impaired participants as they listened to individual and dual speakers narrating different parts of a story. The inclusion of hearing-impaired listeners allowed us to examine how hierarchically organized linguistic units in competing speech streams affect comprehension abilities. We leveraged a hierarchical language model to extract linguistic information at multiple levels--phoneme, syllable, word, phrase, and sentence--and aligned these model activations with the EEG data. Our findings showed distinct neural responses to dual-speaker speech between the two groups. Specifically, compared to normal-hearing listeners, hearing-impaired listeners exhibited poorer model fits at the acoustic, phoneme, and syllable levels as well as the sentence levels, but not at the word and phrase levels. These results suggest that hearing-impaired listeners experience disruptions at both shorter and longer temporal scales, while their processing at medium temporal scales remains unaffected.

A multimodal fMRI dataset unifying naturalistic processes with a rich array of experimental tasks
Cognitive neuroscience has advanced significantly due to the availability of openly shared datasets. Large sample sizes, large amounts of data per person, and diversity in tasks and data types are all desirable, but are difficult to achieve in a single dataset. Here, we present an open dataset with N = 101 participants and 6 hours of scanning per participant, with 6 multifaceted cognitive tasks including 2 hours of naturalistic movie viewing. This datasets combination of ample sample size, extensive data per participant, more than 600 iso hours worth of data, and a wide range of experimental conditions -- including cognitive, affective, social, and somatic/interoceptive tasks -- positions it uniquely for probing important questions in cognitive neuroscience.

Structure transfer and consolidation in visual implicit learning
Transfer learning, the re-application of previously learned higher-level regularities to novel input, is a key challenge in cognition. While previous empirical studies investigated human transfer learning in supervised or reinforcement learning for explicit knowledge, it is unknown whether such transfer occurs during naturally more common implicit and unsupervised learning and if so, how it is related to memory consolidation. We compared the transfer of newly acquired explicit and implicit abstract knowledge during unsupervised learning by extending a visual statistical learning paradigm to a transfer learning context. We found transfer during unsupervised learning but with important differences depending on the explicitness/implicitness of the acquired knowledge. Observers acquiring explicit knowledge during initial learning could transfer the learned structures immediately. In contrast, observers with the same amount but implicit knowledge showed the opposite effect, a structural interference during transfer. However, with sleep between the learning phases, implicit observers switched their behaviour and showed the same pattern of transfer as explicit observers did while still remaining implicit. This effect was specific to sleep and not found after non-sleep consolidation. Our results highlight similarities and differences between explicit and implicit learning while acquiring generalizable higher-level knowledge and relying on consolidation for restructuring internal representations.