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Working memory filtering at encoding and maintenance in healthy ageing, Alzheimer's and Parkinson's disease.
The differential impact on working memory (WM) performance of distractors presented at encoding or during maintenance was investigated in Alzheimer's Disease (AD), Parkinson's Disease (PD) patients, elderly (EHC) and young healthy controls (YHC), (n = 28 per group). Participants reported the orientation of an arrow from a set of either two or three items, with a distractor present either at encoding or at maintenance. MRI data with hippocampal volumes was also acquired. Mean absolute error and mixture model metrics i.e., memory precision, target detection, misbinding (swapping the features of an object with another probed item) and guessing were computed. EHC and PD patients showed good filtering abilities both at encoding and maintenance. However, AD patients exhibited significant filtering deficits specifically when the distractor appeared during maintenance. In healthy ageing there was a prominent decline in WM memory precision, whilst in AD lower target detection and higher guessing were the main sources of error. Conversely, PD was associated only with higher guessing rates. Hippocampal volume was significantly correlated with filtering during maintenance - but not at encoding. These findings demonstrate how healthy ageing and neurodegenerative diseases exhibit distinct patterns of WM impairment, including when filtering irrelevant material either at encoding and maintenance.
Cholinergic degeneration in prodromal and early Parkinson's: a link to present and future disease states.
The neuropathological process in Parkinson's disease (PD) and Lewy body disorders has been shown to extend well beyond the degeneration of the dopaminergic system, affecting other neuromodulatory systems in the brain which play crucial roles in the clinical expression and progression of these disorders. Here, we investigate the role of the macrostructural integrity of the nucleus basalis of Meynert (NbM), the main source of cholinergic input to the cerebral cortex, in cognitive function, clinical manifestation, and disease progression in non-demented subjects with PD and individuals with isolated REM sleep behaviour disorder (iRBD). Using structural MRI data from 393 early PD patients, 128 iRBD patients, and 186 controls from two longitudinal cohorts, we found significantly lower NbM grey matter volume in both PD (β=-12.56, p=0.003) and iRBD (β=-16.41, p=0.004) compared to controls. In PD, higher NbM volume was associated with better higher-order cognitive function (β=0.10, p=0.045), decreased non-motor (β=-0.66, p=0.026) and motor (β=-1.44, p=0.023) symptom burden, and lower risk of future conversion to dementia (Hazard ratio (HR)<0.400, p<0.004). Higher NbM volume in iRBD was associated with decreased future risk of phenoconversion to PD or dementia with Lewy bodies (DLB) (HR<0.490, p<0.016). However, despite similar NbM volume deficits to those seen in PD, associations between NbM structural deficits and current disease burden or clinical state were less pronounced in iRBD. These findings identify NbM volume as a potential biomarker with dual utility: predicting cognitive decline and disease progression in early PD, while also serving as an early indicator of phenoconversion risk in prodromal disease. The presence of structural deficits before clear clinical correlates in iRBD suggests complex compensatory mechanisms may initially mask cholinergic dysfunction, with subsequent failure of these mechanisms potentially contributing to clinical conversion.
Designing better systems to navigate the sepsis-antimicrobial stewardship tension.
Sepsis is a leading cause of preventable death and requires timely antimicrobial treatment to reduce mortality. Despite extensive sepsis management guidelines, high-income countries continue to have considerable rates of sepsis mortality, indicating a gap between guideline quality, usability, and practical application. Simultaneously, the rise of antimicrobial resistance threatens the efficacy of antimicrobial therapies for infection control, underscoring the tension between sepsis management and antimicrobial stewardship. This Personal View explores how system factors, such as people, environments, tools, technologies, and tasks, influence the sepsis-antimicrobial stewardship tension. With the Systems Engineering Initiative for Patient Safety, we use a case study to highlight how organisational pressures, inadequate diagnostic tools, and sociocultural factors drive the gap between work-as-imagined and work-as-done. These latent safety risks that impede guideline adherence and contribute to unintended antimicrobial use highlight the need to design better systems, not blame individuals for non-compliance. We argue that addressing sepsis and antimicrobial resistance requires a holistic systems approach and that every discipline, including policy makers, clinicians, researchers, and drug developers, should adopt systems thinking in the design of interventions intended to address this problem. This shift is essential to ensuring effective care for patients today while safeguarding the effectiveness of antimicrobials tomorrow.
Automated quality control of T1-weighted brain MRI scans for clinical research: methods comparison and design of a quality prediction classifier
T1-weighted (T1w) MRI is widely used in clinical neuroimaging for studying brain structure and its changes, including those related to neurodegenerative diseases, and as anatomical reference for analysing other modalities. Ensuring high-quality T1w scans is vital as image quality affects reliability of outcome measures. However, visual inspection can be subjective and time-consuming, especially with large datasets. The effectiveness of automated quality control (QC) tools for clinical cohorts remains uncertain. In this study, we used T1w scans from elderly participants within ageing and clinical populations to test the accuracy of existing QC tools with respect to visual QC and to establish a new quality prediction framework for clinical research use. Four datasets acquired from multiple scanners and sites were used (N = 2438, 11 sites, 39 scanner manufacturer models, 3 field strengths – 1.5T, 3T, 2.9T, patients and controls, average age 71 ± 8 years). All structural T1w scans were processed with two standard automated QC pipelines (MRIQC and CAT12). The agreement of the accept-reject ratings was compared between the automated pipelines and with visual QC. We then designed a quality prediction framework that combines the QC measures from the existing automated tools and is trained on clinical research datasets. We tested the classifier performance using cross-validation on data from all sites together, also examining the performance across diagnostic groups. We then tested the generalisability of our approach when leaving one site out and explored how well our approach generalises to data from a different scanner manufacturer and/or field strength from those used for training, as well as on an unseen new dataset of healthy young participants with movement related artefacts. Our results show significant agreement between automated QC tools and visual QC (Kappa=0.30 with MRIQC predictions; Kappa=0.28 with CAT12’s rating) when considering the entire dataset, but the agreement was highly variable across datasets. Our proposed robust undersampling boost (RUS) classifier achieved 87.7% balanced accuracy on the test data combined from different sites (with 86.6% and 88.3% balanced accuracy on scans from patients and controls respectively). This classifier was also found to be generalisable on different combinations of training and test datasets (average balanced accuracy of leave-one-site-out = 78.2%; exploratory models on field strengths and manufacturers = 77.7%; movement related artefact dataset when including 1% scans in the training = 88.5%). While existing QC tools may not be robustly applicable to datasets comprised of older adults, they produce quality metrics that can be leveraged to train a more robust quality control classifiers for ageing and clinical cohorts.
FoxO1-zDHHC4-CD36 S-Acylation Axis Drives Metabolic Dysfunction in Diabetes.
BACKGROUND: The fatty acid (FA) transporter CD36 (FA translocase/cluster of differentiation 36) is the gatekeeper of cardiac FA metabolism. Preferential localization of CD36 to the sarcolemma is one of the initiating cellular responses in the development of muscle insulin resistance and the type 2 diabetic heart. Posttranslational S-acylation controls protein trafficking, and in this study, we hypothesized that increased CD36 S-acylation may underpin the preferential sarcolemmal localization of CD36, driving metabolic and contractile dysfunction in diabetes. METHODS AND RESULTS: Type 2 diabetes increased cardiac CD36 S-acylation, CD36 sarcolemmal localization, FA oxidation rates, and triglyceride storage in the diabetic heart. CD36 S-acylation was increased in diabetic rats, db/db mice, diabetic pigs, and insulin-resistant human iPSC-derived cardiomyocytes, demonstrating conservation between species. The enzyme responsible for S-acylating CD36, zDHHC4, was transcriptionally upregulated in the diabetic heart, and genetic silencing of zDHHC4 using siRNA or lentiviral shRNA decreased CD36 S-acylation. We identified that zDHHC4 expression is under the regulation of the transcription factor FoxO (forkhead box O) 1, as FoxO1 binds to the promotor of zDHHC4 and induces its transcription, as assessed using chromatin immunoprecipitation-seq, chromatin immunoprecipitation-quantitative PCR, luciferase assays, and siRNA silencing. Diabetic mice with cardiomyocyte-specific FoxO1 deletion had decreased cardiac zDHHC4 expression and decreased CD36 S-acylation, which was further confirmed using diabetic mice treated with the FoxO1 inhibitor AS1842856. Pharmacological inhibition of zDHHC enzymes in diabetic hearts decreased CD36 S-acylation, sarcolemmal CD36 content, FA oxidation rates, and triglyceride storage, culminating in improved cardiac function in diabetes. Conversely, inhibiting the deacylating enzymes in control hearts increased CD36 S-acylation, sarcolemmal CD36 content, and FA metabolic rates in control hearts, recapitulating the metabolic phenotype seen in diabetic hearts. CONCLUSIONS: Activation of the FoxO1-zDHHC4-CD36 S-acylation axis in diabetes drives metabolic and contractile dysfunction in type 2 diabetic heart.
Loss of the NF-κB negative regulator Pirk in Drosophila links brain and gut immunity to neurodegeneration
A gut-brain axis influenced by host innate immunity and resident microbiota has been implicated in neurological conditions including Alzheimer's disease. However, the precise connection of innate immunity to Alzheimer's disease remains unclear. Using Pirk, a negative regulator of the IMD/NF-κB pathway in Drosophila, we studied the neurological phenotypes induced when genetically predisposing flies to chronically over-active immunity. Pirk mutants exhibited age-dependent neurological phenotypes such as reduced locomotion and altered sleep patterns coupled to an increased number of brain lesions. Gut-specific pirk-RNA interference led to earlier onset of the neurological phenotypes which, alongside changes in intestinal bacteria in pirk mutants, highlighted a potential early role for the intestinal ecosystem in the onset of neurodegeneration. In contrast, glia-specific RNA interference of pirk resulted in late onset of the relevant phenotypes suggesting a later contribution of the nervous system to the underlying neuropathology. Knockout of the antimicrobial peptide (AMP) gene AttacinD or rearing flies in axenic conditions recovered some of the neurological phenotypes, suggesting both chronic AMP gene expression as well as gut bacteria changes as mediators. Our results indicate an evolutionarily conserved path to neurodegeneration linked to dysregulated immunity. They also reveal that in this context, age-dependent neurodegeneration can happen in less complex non-vertebrate brains in the absence of beta-amyloid or tau aggregation.
Smad4 and TGFβ1 dependent gene expression signatures in conditional intestinal adenoma, organoids and colorectal cancer.
TGF-β ligands suppress growth yet can paradoxically and potently promote cancer invasion and metastasis depending on downstream pathway mutational context, such as loss of Mothers against decapentaplegic homolog 4 (Smad4). Here, we characterised phenotypes and associated gene expression signatures in conditional murine intestinal adenoma with and without Smad4. Conditional Lgr5-CreERT2 activation in Apcfl/flSmad4fl/fl mice resulted in homozygote floxed alleles (ApcΔ/ΔSmad4Δ/Δ) and adenoma formation. The adenoma phenotype was discordant, with reduced small intestinal adenoma burden yet development of large non-metastatic caecal adenoma with nuclear localisation of phospho-Smad2/3. Derived ApcΔ/ΔSmad4Δ/Δ adenoma organoids resisted TGF-β1 dose dependent growth arrest and cell death (IC50 534 pM) compared to ApcΔ/ΔSmad4+/+ (IC50 24 pM). TGF-β1 (390 pM) altered adenoma bulk mRNA expression most significantly for Id1low and Spp1high in ApcΔ/ΔSmad4Δ/Δ. Single cell RNAseq of caecal adenoma identified expansion of Lgr5low, Pak3high and Id1low progenitor populations in ApcΔ/ΔSmad4Δ/Δ. Of the 76 Smad4 and TGF-β1 dependent genes identified in Apcfl/flSmad4fl/fl adenoma organoids, only 7 human equivalent genes were differentially expressed in SMAD4 mutated colorectal cancer (TCGA cohorts), including ID1low. SMAD4low, ID1low SPP1high and PAK3high all correlated with poorer survival. Murine adenoma identified Smad4 dependent gene expression signatures that require further evaluation as functional biomarker classifiers of SMAD4 mutated cancer subtypes.
Discovery of the bicycle gene family provides new insights into insect manipulation of plant development during gall induction.
Galls are complex structures that develop from plant tissue, providing protection and food for gall-forming organisms, such as insects or mites. However, the molecules used by insects or mites to manipulate plant development have proved elusive. A landmark study has tracked down a gene in a gall-forming aphid that controls whether galls on witch hazel are green or red. The 'green allele' is strongly expressed in aphid salivary glands and represses plant genes used for red color formation. Excitingly, the gene product is part of a large suite of proteins that aphids may use to interact with plant biology.
Clinical Perspectives on Using Remote Measurement Technology in Assessing Epilepsy, Multiple Sclerosis, and Depression: Delphi Study
Background: Multiple sclerosis (MS), epilepsy, and depression are chronic central nervous system conditions in which remote measurement technology (RMT) may offer benefits compared with usual assessment. We previously worked with clinicians, patients, and researchers to develop 13 use cases for RMT: 5 in epilepsy (seizure alert, seizure counting, risk scoring, triage support, and trend analysis), 3 in MS (detecting silent progression, detecting depression in MS, and donating data to a biobank), and 5 in depression (detecting trends, reviewing treatment, self-management, comorbid monitoring, and carer alert). Objective: In this study, we aimed to evaluate the use cases and related implementation issues with an expert panel of clinicians external to our project consortium. Methods: We used a Delphi exercise to validate the use cases and suggest a prioritization among them and to ascertain the importance of a variety of implementation issues related to RMT. The expert panel included clinicians from across Europe who were external to the project consortium. The study had 2 survey rounds (n=23 and n=17) and a follow-up interview round (n=9). Data were analyzed for consensus between participants and for stability between survey rounds. The interviews explored the reasons for answers given in the survey. Results: The findings showed high stability between rounds on questions related to specific use cases but lower stability on questions relating to wider issues around the implementation of RMT. Overall, questions on wider issues also had less consensus. All 5 use cases for epilepsy (seizure alert, seizure counting, risk scoring, triage support, and trend analysis) were considered beneficial, with consensus among participants above the a priori threshold for most questions, although use case 3 (risk scoring) was considered less likely to facilitate or catalyze care. There was very little consensus on the benefits of the use cases in MS, although this may have resulted from a higher dropout rate of MS clinicians (50%). Participants agreed that there would be benefits for all 5 of the depression use cases, although fewer questions on use case 4 (triage support) reached consensus agreement than for depression use cases 1 (detecting trends), 2 (reviewing treatment), 3 (self-management), and 5 (carer alert). The qualitative analysis revealed further insights into each use case and generated 8 themes on practical issues related to implementation. Conclusions: Overall, these findings inform the prioritization of use cases for RMT that could be developed in future work, which may include clinical trials, cost-effectiveness studies, and the commercial development of RMT products and services. Priorities for further development include the use of RMT to provide more accurate records of symptoms and treatment response than is currently possible and to provide data that could help inform patient triage and generate timely alerts for patients and carers.
The Effects of Facilitation and Inhibition During Multimodal Somatosensory Integration
The somatosensory system, including modalities such as touch, temperature, and pain, is essential for perceiving and interacting with the environment. When individuals encounter different somatosensory modalities, they interact through a process called multimodal somatosensory integration. This integration is essential for accurate perception, motor coordination, pain management, and adaptive behavior. Disruptions in this process can lead to a variety of sensory disorders and complicate rehabilitation efforts. However, research on the behavioral patterns and neural mechanisms underlying multimodal somatosensory integration remains limited. According to previous studies, multimodal somatosensory integration can result in facilitative or inhibitory effects depending on factors like stimulus type, intensity, and spatial proximity. Facilitative effects are observed primarily when stimuli from the same sensory modality (e. g., two touch or temperature stimuli) are presented simultaneously, leading to amplified perceptual strength and quicker reaction times. Additionally, certain external factors, such as cooling, can increase sensitivity to other sensory inputs, further promoting facilitative integration. In contrast, inhibitory effects may also emerge when stimuli from different sensory modalities interact, particularly between touch and pain. Under such conditions, one sensory input (e.g., vibration or non-noxious temperature stimulation) can effectively reduce the perceived intensity of the other, often resulting in reduced pain perception. These facilitative and inhibitory interactions are critical for efficient processing in a multi-stimulus environment and play a role in modulating the experience of somatosensory inputs in both normal and clinical contexts. The neural mechanisms underlying multimodal somatosensory integration are multi-tiered, encompassing peripheral receptors, the spinal cord, and various cortical structures. Facilitative integration relies on the synchronous activation of peripheral receptors, which transmit enhanced signals to higher processing centers. At the cortical level, areas such as the primary and secondary somatosensory cortex, through multimodal neuron responses, facilitate combined representation and amplification of sensory signals. In particular, the thalamus is a significant relay station where multisensory neurons exhibit superadditive responses, contributing to facilitation by enhancing signal strength when multiple inputs are present. Inhibitory integration, on the other hand, is mediated by mechanisms within the spinal cord, such as gating processes that limit transmission of competing sensory signals, thus diminishing the perceived intensity of certain inputs. At the cortical level, lateral inhibition within the somatosensory cortex plays a key role in reducing competing signals from non-target stimuli, enabling prioritized processing of the most relevant sensory input. This layered neural architecture supports the dynamic modulation of sensory inputs, balancing facilitation and inhibition to optimize perception. Understanding the neural pathways involved in somatosensory integration has potential clinical implications for diagnosing sensory disorders and developing therapeutic strategies. Future research should focus on elucidating the specific neural circuitry and mechanisms that contribute to these complex interactions, providing insights into the broader implications of somatosensory integration on behavior and cognition. In summary, this review highlights the importance of multimodal somatosensory integration in enhancing sensory perception. It also underscores the need for further exploration into the neural underpinnings of these processes to advance our understanding of sensory integration and its applications in clinical settings.
Exploration of brain-spinal cord-gut axis abnormalities and the mechanism of acupuncture therapy in irritable bowel syndrome based on magnetic resonance imaging
Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder triggered by the disorder of brain-gut interaction and characterized by abdominal pain, bloating, and altered bowel habits. It is estimated to affect between 5% and 10% of the global population. Although IBS does not have an excessive mortality rate, the disease significantly affects the quality of life and can lead to significant disability. Current treatments mainly focus on relieving abdominal pain and improving bowel habits. However, the effect of drug therapy on the overall symptoms of patients is limited, and the majority of therapeutic drugs are associated with the risk of adverse reactions. Consequently, many patients turn to complementary and alternative therapies to achieve more favorable treatment outcomes. Acupuncture, as a complementary and alternative therapy, has shown potential in the treatment of IBS. Although clinical trials have confirmed the therapeutic effect of acupuncture, its mechanism of action remains unclear, leading to controversy in the global medical community. Researchers, leveraging magnetic resonance imaging (MRI) technology, strive to delve deeply into the biological mechanisms underlying the alleviation of irritable bowel syndrome symptoms through acupuncture therapy, aiming to provide solid support for the scientific basis and efficacy of this treatment method. However, current imaging research primarily focuses on changes in brain structure and function, relatively neglecting the close connection between spinal structure and function and IBS. The spinal cord plays a crucial role in brain-gut interaction, and the development of MRI technology provides a new perspective for exploring the pathogenesis of IBS and the mechanism of acupuncture based on the brain-spinal cord-gut axis. This paper reviews MRI-based studies on abnormalities in brain-spinal cord-gut axis interaction in IBS and acupuncture treatment. Although there have been significant advancements in understanding the causes and using acupuncture to treat IBS, there are still several limitations that need to be addressed. One limitation is the insufficient number of imaging studies on the spinal cord, which hinders our comprehensive understanding of the development of IBS and the underlying mechanisms of acupuncture therapy. In the future, it is necessary to enhance the imaging study of the spinal cord and conduct a thorough analysis of the brain-spinal cord-gut axis mechanism. This will enable us to establish a scientific foundation for understanding the pathogenesis of IBS and the effectiveness of acupuncture treatment. Furthermore, the current research on the impact of acupuncture on IBS primarily concentrates on describing the phenomenon and comparing data but fails to incorporate the principles of neuroscience pain theory. In the future, it is important to prioritize the integration of pain theory and thoroughly investigate the impact of acupuncture on the primary pathways of pain transmission and processing. This will help us understand the intricate mechanism of acupuncture analgesia and facilitate the broader application of acupuncture therapy.
Asia's Wolves and Synergies With Big Cats
In Asia, carnivore conservation is often focused on charismatic big cats. Opportunities to conserve the entire carnivore guild are frequently overlooked by channeling conservation and mitigation efforts into single-species conservation. We synthesize experiences across Asia to explore these challenges and propose mitigations to maximize conservation benefits for the entire carnivore guild. Seven challenges for wolves (Canis lupus) in Asia are highlighted: wolves (1) have been neglected over decades of single-species conservation, (2) receive less cultural appreciation in many regions, (3) are subject to lax legislation and law enforcement, (4) are often blamed disproportionately for livestock depredation, (5) are often considered more abundant than they are, (6), receive disproportionately little attention from the scientific and conservation communities relative to their ecological importance, and (7) are threatened ecologically and genetically by increasing feral dog populations. As a result, the status of wolves across Asia is poorly documented, there is an enhanced risk of losing significant evolutionary lineages, and it detracts from research and conservation opportunities to preserve the entire carnivore guild. We propose various remedies, such as widening the scope of existing conservation programs, building awareness and knowledge of communities and law enforcement agencies, and more research to inform conservation and legislation.
Correction to: Identifying remnant biodiversity hotspots in Southern Asia reveals disequilibrium in mammalian communities (Biodiversity and Conservation, (2024), 33, 11, (3057-3074), 10.1007/s10531-024-02902-0)
In this article, Susana Rostro-García at affiliation “Wildlife Conservation Research Unit, Department of Biology, The Recanati-Kaplan Centre, University of Oxford, Tubney House, Tubney, Oxon, OX13 5QL, UK” was missing from the author’s list. The original article has been corrected.
Sex differences in clinical phenotypes of behavioral variant frontotemporal dementia.
INTRODUCTION: Higher male prevalence in sporadic behavioral variant frontotemporal dementia (bvFTD) has been reported. We hypothesized differences in phenotypes between genetic and sporadic bvFTD females resulting in underdiagnosis of sporadic bvFTD females. METHODS: We included genetic and sporadic bvFTD patients from two multicenter cohorts. We compared behavioral and cognitive symptoms, and gray matter volumes, between genetic and sporadic cases in each sex. RESULTS: Females with sporadic bvFTD showed worse compulsive behavior (p = 0.026) and language impairments (p = 0.024) compared to females with genetic bvFTD (n = 152). Genetic bvFTD females had smaller gray matter volumes than sporadic bvFTD females, particularly in the parietal lobe. DISCUSSION: Females with sporadic bvFTD exhibit a distinct clinical phenotype compared to females with genetic bvFTD. This difference may explain the discrepancy in prevalence between genetic and sporadic cases, as some females without genetic mutations may be misdiagnosed due to atypical bvFTD symptom presentation. HIGHLIGHTS: Sex ratio is equal in genetic behavioral variant of frontotemporal dementia (bvFTD), whereas more males are present in sporadic bvFTD. Distinct neuropsychiatric phenotypes exist between sporadic and genetic bvFTD in females. Phenotype might explain the sex ratio difference between sporadic and genetic cases.
Neural dynamics of reselecting visual and motor contents in working memory after external interference.
In everyday tasks, we must often shift our focus away from internal representations held in working memory to engage with perceptual events in the external world. Here, we investigated how our internal focus is reestablished following an interrupting task by tracking the reselection of visual representations and their associated action plans in working memory. Specifically, we ask whether reselection occurs for both visual and motor memory attributes and when this reselection occurs. We developed a visual-motor working-memory task in which participants were retrospectively cued to select one of two memory items before being interrupted by a perceptual discrimination task. To determine what information was reselected, the memory items had distinct visual and motor attributes. To determine when internal representations were reselected, the interrupting task was presented at one of three distinct time points following the retro-cue. We employed electroencephalography time-frequency analyses to track the initial selection and later reselection of visual and motor representations, as operationalized through modulations of posterior alpha (8-12 Hz) activity relative to the memorized item location (visual) and of central beta (13-30 Hz) activity relative to the required response hand (motor). Our results showed that internal visual and motor contents were concurrently reselected immediately after completing the interrupting task, rather than only when internal information was required for memory-guided behavior. Thus, following interruption, we swiftly resume our internal focus in working memory through the simultaneous reselection of memorized visual representations and their associated action plans, thereby restoring internal contents to a ready-to-use state.Significance statement A key challenge for working memory is to maintain past visual representations and their associated actions while engaging with the external environment. Our cognitive system must, therefore, often juggle multiple tasks within a common time frame. Despite the ubiquity of multi-task situations in everyday life, working memory has predominantly been studied devoid of additional perceptual, attentional, and response demands during the retention interval. Here, we investigate the neural dynamics of returning to internal contents following task-relevant interruptions. Particularly, we identify which attributes of internal representations are reselected and when this reselection occurs. Our findings demonstrate that both visual and motor contents are reselected immediately and in tandem after completion of an external, interrupting task.
Integrative role of CTPS cytoophidia in polyploid tissue growth and nutrient adaptation
Tissue growth and development are fundamental to organismal survival, requiring precise coordination of metabolic processes, nutrient availability, and signaling pathways. Cytidine triphosphate synthase (CTPS) is a rate-limiting enzyme in nucleotide biosynthesis and assembles filamentous cytoophidia, conserved across species. Despite increasing interest in cytoophidia, how CTPS filaments integrate metabolic and signaling cues to drive cell size and tissue growth remains incompletely understood. Using RNA interference and clustered regularly interspaces short palindromic repeats (CRISPR) / CRISPR-associate nuclease 9 gene editing, we generated CTPS-knockdown and point-mutated mutants to investigate the role of cytoophidia in cell growth. Specifically, we introduced the H355A mutation, which disrupts CTPS filament formation without affecting its enzymatic activity. Our findings revealed that CTPS depletion or filament disruption significantly impairs growth in polyploid organs, such as the fat body and salivary glands, underscoring the pivotal role of CTPS cytoophidia in cell growth regulation. Mutants lacking cytoophidia exhibited reduced DNA replication activity and smaller cell sizes compared to wild-type controls. Mechanistically, we found that nutrient-sensing pathways, particularly insulin-PI3K-Akt signaling pathway, regulate CTPS expression and cytoophidia formation in response to nutrient availability. Activation of the sterol regulatory element-binding protein partially rescued the growth defects caused by CTPS depletion. These findings provide new insights into the molecular mechanisms of the regulation of CTPS filaments, highlighting their role as critical mediators of tissue growth by integrating environmental demands, metabolism, and signaling pathways to regulate cell size and nutrient adaptation.