2,645 results on '"functional networks"'
Search Results
2. Functional effects of mutations in proteins can be predicted and interpreted by guided selection of sequence covariation information.
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Cocco, Simona, Posant, Lorenzo, and Monasson, Rémi
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AMINO acid sequence , *SPIDER silk , *PROTEINS - Abstract
Predicting the effects of one or more mutations to the in vivo or in vitro properties of a wild-type protein is a major computational challenge, due to the presence of epistasis, that is, of interactions between amino acids in the sequence. We introduce a computationally efficient procedure to build minimal epistatic models to predict mutational effects by combining evolutionary (homologous sequence) and few mutational-scan data. Mutagenesis measurements guide the selection of links in a sparse graphical model, while the parameters on the nodes and the edges are inferred from sequence data. We show, on 10 mutational scans, that our pipeline exhibits performances comparable to state-of-the-art deep networks trained on many more data, while requiring much less parameters and being hence more interpretable. In particular, the identified interactions adapt to the wild-type protein and to the fitness or biochemical property experimentally measured, mostly focus on key functional sites, and are not necessarily related to structural contacts. Therefore, our method is able to extract information relevant for one mutational experiment from homologous sequence data reflecting the multitude of structural and functional constraints acting on proteins throughout evolution. [ABSTRACT FROM AUTHOR]
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- 2024
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3. Monoaminergic network dysfunction and development of depression in multiple sclerosis: a longitudinal investigation.
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Mistri, Damiano, Valsasina, Paola, Storelli, Loredana, Filippi, Massimo, and Rocca, Maria A.
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MULTIPLE sclerosis , *INDEPENDENT component analysis , *SEROTONIN transporters , *CEREBELLAR cortex , *CINGULATE cortex - Abstract
Background: Monoaminergic network dysfunction is thought to underpin depression in multiple sclerosis (MS) patients. However, longitudinal studies are lacking. Objectives: Here, we investigated the association between development of depressive symptoms in MS and changes of resting-state functional connectivity (RS FC) within monoaminergic networks. Methods: Forty-nine MS patients without depression [Montgomery–Asberg Depression Scale (MADRS) ≤ 9] and 27 healthy controls underwent clinical and 3.0 T RS FC assessment at baseline and after a median follow-up of 1.6 years (interquartile range 1.0–2.1 years). Monoamine-related RS FC was derived by independent component analysis, constrained to PET atlases for dopamine, noradrenaline and serotonin transporters. Longitudinal changes of RS FC within monoaminergic networks and their correlations with MADRS scores were assessed. Results: At baseline, MS patients showed decreased RS FC vs healthy controls in all PET-guided monoaminergic networks in frontal, cingulate and cerebellar cortices, and increased RS FC in parieto-occipital regions. Fourteen (29%) MS patients developed depressive symptoms (MADRS > 9) at follow-up (D-MS) and exhibited widespread RS FC decrease over time in the PET-guided dopamine network, mainly in orbitofrontal, occipital, anterior cingulate and precuneal cortices compared to patients who did not develop depressive symptoms. In D-MS, decreased RS FC over time was also observed in parahippocampal and occipital regions of the PET-guided noradrenaline network. Decreased RS FC over time in dopamine and noradrenaline PET-guided networks correlated with concomitant increased MADRS scores (r = range − 0.65/− 0.61, p < 0.001). Conclusions: The development of depressive symptoms in MS patients was associated with specific RS FC changes within the dopamine and noradrenaline networks. [ABSTRACT FROM AUTHOR]
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- 2024
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4. Network‐based analysis predicts interacting genetic modifiers from a meta‐mapping study of spike–wave discharge in mice.
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Lara, Montana Kay, Brabec, Jeffrey L., Hernan, Amanda E., Scott, Rod C., Tyler, Anna L., and Mahoney, J. Matthew
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CELL cycle regulation , *GENE expression , *QUANTITATIVE genetics , *GENOME-wide association studies , *GENE regulatory networks , *CHROMOSOMES - Abstract
Absence seizures are characterized by brief lapses in awareness accompanied by a hallmark spike‐and‐wave discharge (SWD) electroencephalographic pattern and are common to genetic generalized epilepsies (GGEs). While numerous genes have been associated with increased risk, including some Mendelian forms with a single causal allele, most cases of GGE are idiopathic and there are many unknown genetic modifiers of GGE influencing risk and severity. In a previous meta‐mapping study, crosses between transgenic C57BL/6 and C3HeB/FeJ strains, each carrying one of three SWD‐causing mutations (Gabrg2tm1Spet(R43Q), Scn8a8j or Gria4spkw1), demonstrated an antagonistic epistatic interaction between loci on mouse chromosomes 2 and 7 influencing SWD. These results implicate universal modifiers in the B6 background that mitigate SWD severity through a common pathway, independent of the causal mutation. In this study, we prioritized candidate modifiers in these interacting loci. Our approach integrated human genome‐wide association results with gene interaction networks and mouse brain gene expression to prioritize candidate genes and pathways driving variation in SWD outcomes. We considered candidate genes that are functionally associated with human GGE risk genes and genes with evidence for coding or non‐coding allele effects between the B6 and C3H backgrounds. Our analyses output a summary ranking of gene pairs, one gene from each locus, as candidates for explaining the epistatic interaction. Our top‐ranking gene pairs implicate microtubule function, cytoskeletal stability and cell cycle regulation as novel hypotheses about the source of SWD variation across strain backgrounds, which could clarify underlying mechanisms driving differences in GGE severity in humans. [ABSTRACT FROM AUTHOR]
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- 2024
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5. Divergent pattern of functional connectivity within the dorsal attention network differentiates schizophrenia and bipolar disorder patients
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Adrian Andrzej Chrobak, Sylwia Bielak, Dominik Nowaczek, Aleksandra Żyrkowska, Anna Maria Sobczak, Magdalena Fafrowicz, Amira Bryll, Tadeusz Marek, Dominika Dudek, and Marcin Siwek
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parietal cortex ,frontal eye fields ,resting state ,functional networks ,schizophrenia ,bipolar disorder ,Psychiatry ,RC435-571 - Abstract
IntroductionSchizophrenia (SZ) and bipolar disorder (BD) share common clinical features, symptoms, and neurocognitive deficits, which results in common misdiagnosis. Recently, it has been suggested that alterations within brain networks associated with perceptual organization yield potential to distinguish SZ and BD individuals. The aim of our study was to evaluate whether functional connectivity (FC) of the dorsal attention network (DAN) may differentiate both conditionsMethodsThe study involved 90 participants: 30 remitted SZ patients, 30 euthymic BD patients, and 30 healthy controls (HC). Resting state functional magnetic resonance imaging was used to compare the groups in terms of the FC within the core nodes of the DAN involving frontal eye fields (FEF) and intraparietal sulcus (IPS)ResultsBD patients presented weaker inter-hemispheric FC between right and left FEF than HC. While SZ did not differ from HC in terms of inter-FEF connectivity, they presented increased inter- and intra-hemispheric FC between FEF and IPS. When compared with BD, SZ patients showed increased FC between right FEF and other nodes of the network (bilateral IPS and left FEF)ConclusionWe have shown that altered resting state FC within DAN differentiates BD, SZ, and HC groups. Divergent pattern of FC within DAN, consisting of hypoconnectivity in BD and hyperconnectivity in SZ, might yield a candidate biomarker for differential diagnosis between both conditions. More highly powered studies are needed to confirm these possibilities
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- 2024
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6. Dendrites contribute to the gradient of intrinsic timescales encompassing cortical and subcortical brain networks
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Kaichao Wu and Leonardo L. Gollo
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intrinsic timescales ,dendritic morphology ,neuronal dynamics ,functional networks ,anatomical hierarchy ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
IntroductionCytoarchitectonic studies have uncovered a correlation between higher levels of cortical hierarchy and reduced dendritic size. This hierarchical organization extends to the brain's timescales, revealing longer intrinsic timescales at higher hierarchical levels. However, estimating the contribution of single-neuron dendritic morphology to the hierarchy of timescales, which is typically characterized at a macroscopic level, remains challenging.MethodHere we mapped the intrinsic timescales of six functional networks using functional magnetic resonance imaging (fMRI) data, and characterized the influence of neuronal dendritic size on intrinsic timescales of brain regions, utilizing a multicompartmental neuronal modeling approach based on digitally reconstructed neurons.ResultsThe fMRI results revealed a hierarchy of intrinsic timescales encompassing both cortical and subcortical brain regions. The neuronal modeling indicated that neurons with larger dendritic structures exhibit shorter intrinsic timescales. Together these findings highlight the contribution of dendrites at the neuronal level to the hierarchy of intrinsic timescales at the whole-brain level.DiscussionThis study sheds light on the intricate relationship between neuronal structure, cytoarchitectonic maps, and the hierarchy of timescales in the brain.
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- 2024
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7. Unveiling the core functional networks of cognition: An ontology-guided machine learning approach
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Guowei Wu, Zaixu Cui, Xiuyi Wang, and Yi Du
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Cognitive ontology ,Functional networks ,Machine learning ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Deciphering the functional architecture that underpins diverse cognitive functions is fundamental quest in neuroscience. In this study, we employed an innovative machine learning framework that integrated cognitive ontology with functional connectivity analysis to identify brain networks essential for cognition. We identified a core assembly of functional connectomes, primarily located within the association cortex, which showed superior predictive performance compared to two conventional methods widely employed in previous research across various cognitive domains. Our approach achieved a mean prediction accuracy of 0.13 across 16 cognitive tasks, including working memory, reading comprehension, and sustained attention, outperforming the traditional methods' accuracy of 0.08. In contrast, our method showed limited predictive power for sensory, motor, and emotional functions, with a mean prediction accuracy of 0.03 across 9 relevant tasks, slightly lower than the traditional methods' accuracy of 0.04. These cognitive connectomes were further characterized by distinctive patterns of resting-state functional connectivity, structural connectivity via white matter tracts, and gene expression, highlighting their neurogenetic underpinnings. Our findings reveal a domain-general functional network fingerprint that pivotal to cognition, offering a novel computational approach to explore the neural foundations of cognitive abilities.
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- 2024
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8. Dissecting the impact of Anaplasma phagocytophilum infection on functional networks and community stability of the tick microbiome
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Paulino, Patrícia Gonzaga, Abuin-Denis, Lianet, Maitre, Apolline, Piloto-Sardiñas, Elianne, Obregon, Dasiel, Santos, Huarrisson Azevedo, and Cabezas-Cruz, Alejandro
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- 2024
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9. Low Cost Carriers Induce Specific and Identifiable Delay Propagation Patterns: An Analysis of the EU and US Systems
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Sofia Gil-Rodrigo and Massimiliano Zanin
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Air transport ,low-cost carriers ,delay propagation ,functional networks ,deep learning ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 - Abstract
The impact of air transport delays and their propagation has long been studied, mainly from environmental and mobility viewpoints, using a wide range of data analysis tools and simulations. Less attention has nevertheless been devoted to how delays create meso-scale structures around each airport. In this work we tackle this issue by reconstructing functional networks of delay propagation centred at each airport, and studying their identifiability (i.e. how unique they are) using Deep Learning models. We find that such delay propagation neighbourhoods are highly unique when they correspond to airports with a high share of Low Cost Carriers operations; and demonstrate the robustness of these findings for the EU and US systems, and to different methodological choices. We further discuss some operational implications of this uniqueness.
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- 2024
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10. Intra-V1 functional networks and classification of observed stimuli.
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Ontivero-Ortega, Marlis, Iglesias-Fuster, Jorge, Perez-Hidalgo, Jhoanna, Marinazzo, Daniele, Valdes-Sosa, Mitchell, and Valdes-Sosa, Pedro
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Introduction: Previous studies suggest that co-fluctuations in neural activity within V1 (measured with fMRI) carry information about observed stimuli, potentially reflecting various cognitive mechanisms. This study explores the neural sources shaping this information by using different fMRI preprocessing methods. The common response to stimuli shared by all individuals can be emphasized by using inter-subject correlations or de-emphasized by deconvolving the fMRI with hemodynamic response functions (HRFs) before calculating the correlations. The latter approach shifts the balance towards participant-idiosyncratic activity. Methods: Here, we used multivariate pattern analysis of intra-V1 correlation matrices to predict the Level or Shape of observed Navon letters employing the types of correlations described above. We assessed accuracy in inter-subject prediction of specific conjunctions of properties, and attempted intra-subject cross-classification of stimulus properties (i.e., prediction of one feature despite changes in the other). Weight maps from successful classifiers were projected onto the visual field. A control experiment investigated eye-movement patterns during stimuli presentation. Results: All inter-subject classifiers accurately predicted the Level and Shape of specific observed stimuli. However, successful intra-subject crossclassification was achieved only for stimulus Level, but not Shape, regardless of preprocessing scheme. Weight maps for successful Level classification differed between inter-subject correlations and deconvolved correlations. The latter revealed asymmetries in visual field link strength that corresponded to known perceptual asymmetries. Post-hoc measurement of eyeball fMRI signals did not find differences in gaze between stimulus conditions, and a control experiment (with derived simulations) also suggested that eye movements do not explain the stimulus-related changes in V1 topology. Discussion: Our findings indicate that both inter-subject common responses and participant-specific activity contribute to the information in intra-V1 cofluctuations, albeit through distinct sub-networks. Deconvolution, that enhances subject-specific activity, highlighted interhemispheric links for Global stimuli. Further exploration of intra-V1 networks promises insights into the neural basis of attention and perceptual organization. [ABSTRACT FROM AUTHOR]
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- 2024
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11. Preliminary Proteomic Study of the Porcine Pituitary Gland under Heat Stress.
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Zhou, Qiu, Gao, Yuan, Li, Yin, Xie, Huili, Liu, Xiaoxi, Yong, Yanhong, Li, Youquan, Yu, Zhichao, Ma, Xingbin, and Ju, Xianghong
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PITUITARY gland , *HYPOTHALAMIC-pituitary-adrenal axis , *NERVOUS system , *CELL communication , *PROTEOMICS , *HEATING , *PEPTIDES - Abstract
Although numerous studies have shown that the hypothalamic–pituitary–adrenal axis plays a vital role in the response to environmental stress by mediating the production of a series of hormones, the mechanism underlying these effects has not been elucidated. This study used proteomics techniques to investigate the differentially expressed proteins (DEPs) in the pituitary glands of pigs and to elucidate the potential changes in the immune–neuroendocrine system under heat stress (HS). In total, 2517 peptides corresponding to 205 proteins were detected. A comparison of the expression patterns between HSs and healthy controls revealed 56 DEPs, of which 31 were upregulated and 25 were downregulated. Ingenuity pathway analysis (IPA) was used to reveal the subcellular characteristics, functional pathways, regulatory networks, and upstream regulators of the identified proteins. The results showed that these differentially expressed proteins were involved in intercellular communication, interactions, apoptosis, nervous system development, functions, abnormalities and other functions, and in the regulatory network. Moreover, the upstream regulators of the differentially expressed proteins were mainly transcriptional regulators, hormones, and cytokines. Thus, the functional network and pathway analyses could provide insights into the complexity and dynamics of HS–host interactions and may accelerate our understanding of the mechanisms underlying HS. [ABSTRACT FROM AUTHOR]
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- 2024
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12. Reversibility of Impaired Large-Scale Functional Brain Networks in Cushing's Disease after Surgery Treatment: A Longitudinal Study.
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Cheng, Hewei, Gao, Lu, Jing, Rixing, Hou, Bo, Guo, Xiaopeng, Yao, Yong, Feng, Ming, Xing, Bing, Feng, Feng, and Fan, Yong
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LARGE-scale brain networks , *CUSHING'S syndrome , *FUNCTIONAL magnetic resonance imaging , *DEFAULT mode network - Abstract
Introduction: Chronic exposure to excessive endogenous cortisol leads to brain changes in Cushing's disease (CD). However, it remains unclear how CD affects large-scale functional networks (FNs) and whether these effects are reversible after treatment. This study aimed to investigate functional network changes of CD patients and their reversibility in a longitudinal cohort. Methods: Active CD patients (N = 37) were treated by transsphenoidal pituitary surgery and reexamined 3 months later. FNs were computed from resting-state fMRI data of the CD patients and matched normal controls (NCs, N = 37). A pattern classifier was built on the FNs to distinguish active CD patients from controls and applied to FNs of the CD patients at the 3-month follow-up. Two subgroups of endocrine-remitted CD patients were identified according to their classification scores, referred to as image-based phenotypically (IBP) recovered and unrecovered CD patients, respectively. The informative FNs identified by the classification model were compared between NCs, active CD patients, and endocrine-remitted patients as well as between IBP recovered and unrecovered CD patients to explore their functional network reversibility. Results: All 37 CD patients reached endocrine remission after treatment. The classification model identified three informative FNs, including cerebellar network (CerebN), fronto-parietal network (FPN), and default mode network. Among them, CerebN and FPN partially recovered toward normal at 3 months after treatment. Moreover, the informative FNs were correlated with 24-h urinary-free cortisol and emotion scales in CD patients. Conclusion: These findings suggest that CD patients have aberrant FNs that are partially reversible toward normal after treatment. [ABSTRACT FROM AUTHOR]
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- 2024
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13. Homological Landscape of Human Brain Functional Sub-Circuits.
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Duong-Tran, Duy, Kaufmann, Ralph, Chen, Jiong, Wang, Xuan, Garai, Sumita, Xu, Frederick H., Bao, Jingxuan, Amico, Enrico, Kaplan, Alan D., Petri, Giovanni, Goni, Joaquin, Zhao, Yize, and Shen, Li
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FUNCTIONAL magnetic resonance imaging , *DEFAULT mode network , *FUNCTIONAL connectivity , *SHORT-term memory , *TOPOLOGICAL property - Abstract
Human whole-brain functional connectivity networks have been shown to exhibit both local/quasilocal (e.g., a set of functional sub-circuits induced by node or edge attributes) and non-local (e.g., higher-order functional coordination patterns) properties. Nonetheless, the non-local properties of topological strata induced by local/quasilocal functional sub-circuits have yet to be addressed. To that end, we proposed a homological formalism that enables the quantification of higher-order characteristics of human brain functional sub-circuits. Our results indicate that each homological order uniquely unravels diverse, complementary properties of human brain functional sub-circuits. Noticeably, the H 1 homological distance between rest and motor task was observed at both the whole-brain and sub-circuit consolidated levels, which suggested the self-similarity property of human brain functional connectivity unraveled by a homological kernel. Furthermore, at the whole-brain level, the rest–task differentiation was found to be most prominent between rest and different tasks at different homological orders: (i) Emotion task ( H 0 ), (ii) Motor task ( H 1 ), and (iii) Working memory task ( H 2 ). At the functional sub-circuit level, the rest–task functional dichotomy of the default mode network is found to be mostly prominent at the first and second homological scaffolds. Also at such scale, we found that the limbic network plays a significant role in homological reconfiguration across both the task and subject domains, which paves the way for subsequent investigations on the complex neuro-physiological role of such network. From a wider perspective, our formalism can be applied, beyond brain connectomics, to study the non-localized coordination patterns of localized structures stretching across complex network fibers. [ABSTRACT FROM AUTHOR]
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- 2024
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14. Longitudinal resting-state network connectivity changes in electroconvulsive therapy patients compared to healthy controls.
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Verdijk, Joey P.A.J., van de Mortel, Laurens A., ten Doesschate, Freek, Pottkämper, Julia C.M., Stuiver, Sven, Bruin, Willem B., Abbott, Christopher C., Argyelan, Miklos, Ousdal, Olga T., Bartsch, Hauke, Narr, Katherine, Tendolkar, Indira, Calhoun, Vince, Lukemire, Joshua, Guo, Ying, Oltedal, Leif, van Wingen, Guido, and van Waarde, Jeroen A.
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Electroconvulsive therapy (ECT) is effective for major depressive episodes. Understanding of underlying mechanisms has been increased by examining changes of brain connectivity but studies often do not correct for test-retest variability in healthy controls (HC). In this study, we investigated changes in resting-state networks after ECT in a multicenter study. Functional resting-state magnetic resonance imaging data, acquired before start and within one week after ECT, from 90 depressed patients were analyzed, as well as longitudinal data of 24 HC. Group-information guided independent component analysis (GIG-ICA) was used to spatially restrict decomposition to twelve canonical resting-state networks. Selected networks of interest were the default mode network (DMN), salience network (SN), and left and right frontoparietal network (LFPN, and RFPN). Whole-brain voxel-wise analyses were used to assess group differences at baseline, group by time interactions, and correlations with treatment effectiveness. In addition, between-network connectivity and within-network strengths were computed. Within-network strength of the DMN was lower at baseline in ECT patients which increased after ECT compared to HC, after which no differences were detected. At baseline, ECT patients showed lower whole-brain voxel-wise DMN connectivity in the precuneus. Increase of within-network strength of the LFPN was correlated with treatment effectiveness. We did not find whole-brain voxel-wise or between-network changes. DMN within-network connectivity normalized after ECT. Within-network increase of the LFPN in ECT patients was correlated with higher treatment effectiveness. In contrast to earlier studies, we found no whole-brain voxel-wise changes, which highlights the necessity to account for test-retest effects. • The default mode network normalizes after electroconvulsive therapy. • The left frontoparietal network is associated with treatment effectiveness. • Absence of voxel-wise changes shows necessity to account for test-retest effects. [ABSTRACT FROM AUTHOR]
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- 2024
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15. A general exposome factor explains individual differences in functional brain network topography and cognition in youth
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Arielle S. Keller, Tyler M. Moore, Audrey Luo, Elina Visoki, Mārtiņš M. Gataviņš, Alisha Shetty, Zaixu Cui, Yong Fan, Eric Feczko, Audrey Houghton, Hongming Li, Allyson P. Mackey, Oscar Miranda-Dominguez, Adam Pines, Russell T. Shinohara, Kevin Y. Sun, Damien A. Fair, Theodore D. Satterthwaite, and Ran Barzilay
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Cognition ,Functional networks ,Development ,Environment ,Exposome ,Topography ,Neurophysiology and neuropsychology ,QP351-495 - Abstract
Childhood environments are critical in shaping cognitive neurodevelopment. With the increasing availability of large-scale neuroimaging datasets with deep phenotyping of childhood environments, we can now build upon prior studies that have considered relationships between one or a handful of environmental and neuroimaging features at a time. Here, we characterize the combined effects of hundreds of inter-connected and co-occurring features of a child’s environment (“exposome”) and investigate associations with each child’s unique, multidimensional pattern of functional brain network organization (“functional topography”) and cognition. We apply data-driven computational models to measure the exposome and define personalized functional brain networks in pre-registered analyses. Across matched discovery (n=5139, 48.5% female) and replication (n=5137, 47.1% female) samples from the Adolescent Brain Cognitive Development study, the exposome was associated with current (ages 9–10) and future (ages 11–12) cognition. Changes in the exposome were also associated with changes in cognition after accounting for baseline scores. Cross-validated ridge regressions revealed that the exposome is reflected in functional topography and can predict performance across cognitive domains. Importantly, a single measure capturing a child’s exposome could more accurately and parsimoniously predict cognition than a wealth of personalized neuroimaging data, highlighting the importance of children’s complex, multidimensional environments in cognitive neurodevelopment.
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- 2024
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16. Alterations in spatiotemporal characteristics of dynamic networks in juvenile myoclonic epilepsy
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Ke, Ming, Luo, Xiaofei, Guo, Yi, Zhang, Juli, Ren, Xupeng, and Liu, Guangyao
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- 2024
- Full Text
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17. Functional networks of working memory abilities in children with complex congenital heart disease: a sleep EEG study.
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Wehrle, Flavia M., Furrer, Melanie, Feldmann, Maria, Liamlahi, Rabia, Naef, Nadja, O'Gorman, Ruth, Latal, Beatrice, and Huber, Reto
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SHORT-term memory , *CONGENITAL heart disease , *SLOW wave sleep , *DROWSINESS , *ELECTROENCEPHALOGRAPHY , *SLEEP , *AGENESIS of corpus callosum - Abstract
Working memory is frequently impaired in children with complex congenital heart disease (CHD), but little is known about the functional neuronal correlates. Sleep slow wave activity (SWA; 1–4.5 Hz EEG power) has previously been shown to reliably map neurofunctional networks of cognitive abilities in children with and without neurodevelopmental impairments. This study investigated whether functional networks of working memory abilities are altered in children with complex CHD using EEG recordings during sleep. Twenty-one children with complex CHD (aged 10.9 [SD: 0.3] years) and 17 typically-developing peers (10.5 [0.7] years) completed different working memory tasks and an overnight high-density sleep EEG recording (128 electrodes). The combined working memory score tended to be lower in children with complex CHD (CHD group: −0.44 [1.12], typically-developing group: 0.55 [1.24], d = 0.59, p =.06). The working memory score and sleep SWA of the first hour of deep sleep were correlated over similar brain regions in both groups: Strong positive associations were found over prefrontal and fronto-parietal brain regions – known to be part of the working memory network – and strong negative associations were found over central brain regions. Within these working memory networks, the associations between working memory abilities and sleep SWA (r between −.36 and.58, all p <.03) were not different between the two groups (no interactions, all p >.05). The current findings suggest that sleep SWA reliably maps working memory networks in children with complex CHD and that these functional networks are generally preserved in these patients. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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18. Intra-V1 functional networks and classification of observed stimuli
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Marlis Ontivero-Ortega, Jorge Iglesias-Fuster, Jhoanna Perez-Hidalgo, Daniele Marinazzo, Mitchell Valdes-Sosa, and Pedro Valdes-Sosa
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V1 ,fMRI ,functional networks ,SVM-classifier ,Navon task ,weight-maps ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
IntroductionPrevious studies suggest that co-fluctuations in neural activity within V1 (measured with fMRI) carry information about observed stimuli, potentially reflecting various cognitive mechanisms. This study explores the neural sources shaping this information by using different fMRI preprocessing methods. The common response to stimuli shared by all individuals can be emphasized by using inter-subject correlations or de-emphasized by deconvolving the fMRI with hemodynamic response functions (HRFs) before calculating the correlations. The latter approach shifts the balance towards participant-idiosyncratic activity.MethodsHere, we used multivariate pattern analysis of intra-V1 correlation matrices to predict the Level or Shape of observed Navon letters employing the types of correlations described above. We assessed accuracy in inter-subject prediction of specific conjunctions of properties, and attempted intra-subject cross-classification of stimulus properties (i.e., prediction of one feature despite changes in the other). Weight maps from successful classifiers were projected onto the visual field. A control experiment investigated eye-movement patterns during stimuli presentation.ResultsAll inter-subject classifiers accurately predicted the Level and Shape of specific observed stimuli. However, successful intra-subject cross-classification was achieved only for stimulus Level, but not Shape, regardless of preprocessing scheme. Weight maps for successful Level classification differed between inter-subject correlations and deconvolved correlations. The latter revealed asymmetries in visual field link strength that corresponded to known perceptual asymmetries. Post-hoc measurement of eyeball fMRI signals did not find differences in gaze between stimulus conditions, and a control experiment (with derived simulations) also suggested that eye movements do not explain the stimulus-related changes in V1 topology.DiscussionOur findings indicate that both inter-subject common responses and participant-specific activity contribute to the information in intra-V1 co-fluctuations, albeit through distinct sub-networks. Deconvolution, that enhances subject-specific activity, highlighted interhemispheric links for Global stimuli. Further exploration of intra-V1 networks promises insights into the neural basis of attention and perceptual organization.
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- 2024
- Full Text
- View/download PDF
19. Spatial-temporal convolutional attention for discovering and characterizing functional brain networks in task fMRI
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Yiheng Liu, Enjie Ge, Zili Kang, Ning Qiang, Tianming Liu, and Bao Ge
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fMRI ,Functional networks ,Brain function dynamic ,Attention mechanism ,Task-based fMRI ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Functional brain networks (FBNs) are spatial patterns of brain function that play a critical role in understanding human brain function. There are many proposed methods for mapping the spatial patterns of brain function, however they oversimplify the underlying assumptions of brain function and have various limitations such as linearity and independence. Additionally, current methods fail to account for the dynamic nature of FBNs, which limits their effectiveness in accurately characterizing these networks. To address these limitations, we present a novel deep learning and spatial-wise attention based model called Spatial-Temporal Convolutional Attention (STCA) to accurately model dynamic FBNs. Specifically, we train STCA in a self-supervised manner by utilizing a Convolutional Autoencoder to guide the STCA module in assigning higher attention weights to regions of functional activity. To validate the reliability of the results, we evaluate our approach on the HCP-task motor behavior dataset, the experimental results demonstrate that the STCA derived FBNs have higher spatial similarity with the templates and that the spatial similarity between the templates and the FBNs derived by STCA fluctuates with the task design over time, suggesting that STCA can reflect the dynamic changes of brain function, providing a powerful tool to better understand human brain function. Code is available at https://github.com/SNNUBIAI/STCAE.
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- 2024
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20. Brain’s Networks and Their Functional Significance in Cognition
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Dragomir, Andrei, Omurtag, Ahmet, and Thakor, Nitish V., editor
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- 2023
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21. Emergence of canonical functional networks from the structural connectome.
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Xie, Xihe, Cai, Chang, Damasceno, Pablo F, Nagarajan, Srikantan S, and Raj, Ashish
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Complex Laplacian ,Functional networks ,Graph Laplacian ,Structural connectivity ,Neurosciences ,1.1 Normal biological development and functioning ,Neurological ,Neurology & Neurosurgery ,Medical and Health Sciences ,Psychology and Cognitive Sciences - Abstract
How do functional brain networks emerge from the underlying wiring of the brain? We examine how resting-state functional activation patterns emerge from the underlying connectivity and length of white matter fibers that constitute its "structural connectome". By introducing realistic signal transmission delays along fiber projections, we obtain a complex-valued graph Laplacian matrix that depends on two parameters: coupling strength and oscillation frequency. This complex Laplacian admits a complex-valued eigen-basis in the frequency domain that is highly tunable and capable of reproducing the spatial patterns of canonical functional networks without requiring any detailed neural activity modeling. Specific canonical functional networks can be predicted using linear superposition of small subsets of complex eigenmodes. Using a novel parameter inference procedure we show that the complex Laplacian outperforms the real-valued Laplacian in predicting functional networks. The complex Laplacian eigenmodes therefore constitute a tunable yet parsimonious substrate on which a rich repertoire of realistic functional patterns can emerge. Although brain activity is governed by highly complex nonlinear processes and dense connections, our work suggests that simple extensions of linear models to the complex domain effectively approximate rich macroscopic spatial patterns observable on BOLD fMRI.
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- 2021
22. Mechanistic insights into the interactions between cancer drivers and the tumour immune microenvironment
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Hrvoje Misetic, Mohamed Reda Keddar, Jean-Pierre Jeannon, and Francesca D. Ciccarelli
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Cancer driver genes ,Cancer immunology ,Computational biology ,Head and neck cancer ,Functional networks ,Medicine ,Genetics ,QH426-470 - Abstract
Abstract Background The crosstalk between cancer and the tumour immune microenvironment (TIME) has attracted significant interest in the latest years because of its impact on cancer evolution and response to treatment. Despite this, cancer-specific tumour-TIME interactions and their mechanistic insights are still poorly understood. Methods Here, we compute the significant interactions occurring between cancer-specific genetic drivers and five anti- and pro-tumour TIME features in 32 cancer types using Lasso regularised ordinal regression. Focusing on head and neck squamous cancer (HNSC), we rebuild the functional networks linking specific TIME driver alterations to the TIME state they associate with. Results The 477 TIME drivers that we identify are multifunctional genes whose alterations are selected early in cancer evolution and recur across and within cancer types. Tumour suppressors and oncogenes have an opposite effect on the TIME and the overall anti-tumour TIME driver burden is predictive of response to immunotherapy. TIME driver alterations predict the immune profiles of HNSC molecular subtypes, and perturbations in keratinization, apoptosis and interferon signalling underpin specific driver-TIME interactions. Conclusions Overall, our study delivers a comprehensive resource of TIME drivers, gives mechanistic insights into their immune-regulatory role, and provides an additional framework for patient prioritisation to immunotherapy. The full list of TIME drivers and associated properties are available at http://www.network-cancer-genes.org .
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- 2023
- Full Text
- View/download PDF
23. Neonatal cortical activity organizes into transient network states that are affected by vigilance states and brain injury
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Mohammad Khazaei, Khadijeh Raeisi, Sampsa Vanhatalo, Filippo Zappasodi, Silvia Comani, and Anton Tokariev
- Subjects
Neonatal EEG ,Sleep ,Brain dynamics ,Functional networks ,Hypoxic-ischemic encephalopathy ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Early neurodevelopment is critically dependent on the structure and dynamics of spontaneous neuronal activity; however, the natural organization of newborn cortical networks is poorly understood. Recent adult studies suggest that spontaneous cortical activity exhibits discrete network states with physiological correlates. Here, we studied newborn cortical activity during sleep using hidden Markov modeling to determine the presence of such discrete neonatal cortical states (NCS) in 107 newborn infants, with 47 of them presenting with a perinatal brain injury. Our results show that neonatal cortical activity organizes into four discrete NCSs that are present in both cardinal sleep states of a newborn infant, active and quiet sleep, respectively. These NCSs exhibit state-specific spectral and functional network characteristics. The sleep states exhibit different NCS dynamics, with quiet sleep presenting higher fronto-temporal activity and a stronger brain-wide neuronal coupling. Brain injury was associated with prolonged lifetimes of the transient NCSs, suggesting lowered dynamics, or flexibility, in the cortical networks. Taken together, the findings suggest that spontaneously occurring transient network states are already present at birth, with significant physiological and pathological correlates; this NCS analysis framework can be fully automatized, and it holds promise for offering an objective, global level measure of early brain function for benchmarking neurodevelopmental or clinical research.
- Published
- 2023
- Full Text
- View/download PDF
24. Recovery of Brain Network Integration and Segregation During the Loss and Recovery of Consciousness Induced by Sevoflurane
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Kangli Dong, Qishun Wei, Delin Zhang, Lu Zhang, Guozheng Wang, Xing Chen, and Jun Liu
- Subjects
Anesthesia ,consciousness ,electroencephalogram ,functional networks ,community detection ,Medical technology ,R855-855.5 ,Therapeutics. Pharmacology ,RM1-950 - Abstract
Anesthetic-induced loss of consciousness (LOC) has been studied using functional connectivity (FC) and functional network analysis (FNA), manifested as fragmentation of the whole-brain functional network. However, how the fragmented brain networks reversibly recover during the recovery of consciousness (ROC) remains vague. This study aims to investigate the changes in brain network structure during ROC, to better understand the network fragmentation during anesthesia, thus providing insights into consciousness monitoring. We analyzed EEG data recorded from 15 individuals anesthetized by sevoflurane. By investigating the properties of functional networks generated using different brain atlases and performing community detection for functional networks, we explored the changes in brain network structure to understand how fragmented brain networks recover during the ROC. We observed an overall larger FC magnitude during LOC than in the conscious state. The ROC was accompanied by the increasing binary network efficiency, decreasing FC magnitude, and decreasing community similarity with the functional atlas. Furthermore, we observed a negative correlation between modularity and community number ( $\text{p} < 0.001$ and $\textit {BF}_{{10}} >4000$ , linear regression test), in which modularity increased and community number decreased during ROC. Our results show that a larger FC magnitude reveals excessive synchronization of neuronal activities during LOC. The increasing binary network efficiency, decreasing community number, and decreasing community similarity indicate the recovery of functional network integration. The increasing modularity implies the recovery of functional network segregation during ROC. The results suggest the limitation of FC magnitude and modularity in monitoring anesthetized states and the potential of integrated information theory to evaluate consciousness.
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- 2023
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25. Preliminary Proteomic Study of the Porcine Pituitary Gland under Heat Stress
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Qiu Zhou, Yuan Gao, Yin Li, Huili Xie, Xiaoxi Liu, Yanhong Yong, Youquan Li, Zhichao Yu, Xingbin Ma, and Xianghong Ju
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heat stress ,quantitative proteomics ,pituitary gland ,functional networks ,Science - Abstract
Although numerous studies have shown that the hypothalamic–pituitary–adrenal axis plays a vital role in the response to environmental stress by mediating the production of a series of hormones, the mechanism underlying these effects has not been elucidated. This study used proteomics techniques to investigate the differentially expressed proteins (DEPs) in the pituitary glands of pigs and to elucidate the potential changes in the immune–neuroendocrine system under heat stress (HS). In total, 2517 peptides corresponding to 205 proteins were detected. A comparison of the expression patterns between HSs and healthy controls revealed 56 DEPs, of which 31 were upregulated and 25 were downregulated. Ingenuity pathway analysis (IPA) was used to reveal the subcellular characteristics, functional pathways, regulatory networks, and upstream regulators of the identified proteins. The results showed that these differentially expressed proteins were involved in intercellular communication, interactions, apoptosis, nervous system development, functions, abnormalities and other functions, and in the regulatory network. Moreover, the upstream regulators of the differentially expressed proteins were mainly transcriptional regulators, hormones, and cytokines. Thus, the functional network and pathway analyses could provide insights into the complexity and dynamics of HS–host interactions and may accelerate our understanding of the mechanisms underlying HS.
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- 2024
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26. Homological Landscape of Human Brain Functional Sub-Circuits
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Duy Duong-Tran, Ralph Kaufmann, Jiong Chen, Xuan Wang, Sumita Garai, Frederick H. Xu, Jingxuan Bao, Enrico Amico, Alan D. Kaplan, Giovanni Petri, Joaquin Goni, Yize Zhao, and Li Shen
- Subjects
functional sub-circuit ,functional networks ,homological kernel ,topological data analysis ,Mathematics ,QA1-939 - Abstract
Human whole-brain functional connectivity networks have been shown to exhibit both local/quasilocal (e.g., a set of functional sub-circuits induced by node or edge attributes) and non-local (e.g., higher-order functional coordination patterns) properties. Nonetheless, the non-local properties of topological strata induced by local/quasilocal functional sub-circuits have yet to be addressed. To that end, we proposed a homological formalism that enables the quantification of higher-order characteristics of human brain functional sub-circuits. Our results indicate that each homological order uniquely unravels diverse, complementary properties of human brain functional sub-circuits. Noticeably, the H1 homological distance between rest and motor task was observed at both the whole-brain and sub-circuit consolidated levels, which suggested the self-similarity property of human brain functional connectivity unraveled by a homological kernel. Furthermore, at the whole-brain level, the rest–task differentiation was found to be most prominent between rest and different tasks at different homological orders: (i) Emotion task (H0), (ii) Motor task (H1), and (iii) Working memory task (H2). At the functional sub-circuit level, the rest–task functional dichotomy of the default mode network is found to be mostly prominent at the first and second homological scaffolds. Also at such scale, we found that the limbic network plays a significant role in homological reconfiguration across both the task and subject domains, which paves the way for subsequent investigations on the complex neuro-physiological role of such network. From a wider perspective, our formalism can be applied, beyond brain connectomics, to study the non-localized coordination patterns of localized structures stretching across complex network fibers.
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- 2024
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27. Multilevel synchronization of human β-cells networks
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Nicole Luchetti, Simonetta Filippi, and Alessandro Loppini
- Subjects
functional networks ,multiplex ,metabolic coupling ,calcium wave ,bursting ,slow oscillations ,Electronic computers. Computer science ,QA75.5-76.95 - Abstract
β-cells within the endocrine pancreas are fundamental for glucose, lipid and protein homeostasis. Gap junctions between cells constitute the primary coupling mechanism through which cells synchronize their electrical and metabolic activities. This evidence is still only partially investigated through models and numerical simulations. In this contribution, we explore the effect of combined electrical and metabolic coupling in β-cell clusters using a detailed biophysical model. We add heterogeneity and stochasticity to realistically reproduce β-cell dynamics and study networks mimicking arrangements of β-cells within human pancreatic islets. Model simulations are performed over different couplings and heterogeneities, analyzing emerging synchronization at the membrane potential, calcium, and metabolites levels. To describe network synchronization, we use the formalism of multiplex networks and investigate functional network properties and multiplex synchronization motifs over the structural, electrical, and metabolic layers. Our results show that metabolic coupling can support slow wave propagation in human islets, that combined electrical and metabolic synchronization is realized in small aggregates, and that metabolic long-range correlation is more pronounced with respect to the electrical one.
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- 2023
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28. Large-scale neural dynamics in a shared low-dimensional state space reflect cognitive and attentional dynamics
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Hayoung Song, Won Mok Shim, and Monica D Rosenberg
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brain states ,dynamical systems ,functional networks ,event boundaries ,attention ,Medicine ,Science ,Biology (General) ,QH301-705.5 - Abstract
Cognition and attention arise from the adaptive coordination of neural systems in response to external and internal demands. The low-dimensional latent subspace that underlies large-scale neural dynamics and the relationships of these dynamics to cognitive and attentional states, however, are unknown. We conducted functional magnetic resonance imaging as human participants performed attention tasks, watched comedy sitcom episodes and an educational documentary, and rested. Whole-brain dynamics traversed a common set of latent states that spanned canonical gradients of functional brain organization, with global desynchronization among functional networks modulating state transitions. Neural state dynamics were synchronized across people during engaging movie watching and aligned to narrative event structures. Neural state dynamics reflected attention fluctuations such that different states indicated engaged attention in task and naturalistic contexts, whereas a common state indicated attention lapses in both contexts. Together, these results demonstrate that traversals along large-scale gradients of human brain organization reflect cognitive and attentional dynamics.
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- 2023
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29. Classification of human chronotype based on fMRI network-based statistics.
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Mason, Sophie L., Junges, Leandro, Woldman, Wessel, Facer-Childs, Elise R., de Campos, Brunno M., Bagshaw, Andrew P., and Terry, John R.
- Subjects
CHRONOTYPE ,LARGE-scale brain networks ,FUNCTIONAL magnetic resonance imaging ,BRAIN waves ,MORNINGNESS-Eveningness Questionnaire ,COGNITIVE ability - Abstract
Chronotype--the relationship between the internal circadian physiology of an individual and the external 24-h light-dark cycle--is increasingly implicated in mental health and cognition. Individuals presenting with a late chronotype have an increased likelihood of developing depression, and can display reduced cognitive performance during the societal 9-5 day. However, the interplay between physiological rhythms and the brain networks that underpin cognition and mental health is not well-understood. To address this issue, we use rs-fMRI collected from 16 people with an early chronotype and 22 people with a late chronotype over three scanning sessions. We develop a classification framework utilizing the Network Based-Statistic methodology, to understand if differentiable information about chronotype is embedded in functional brain networks and how this changes throughout the day. We find evidence of subnetworks throughout the day that differ between extreme chronotypes such that high accuracy can occur, describe rigorous threshold criteria for achieving 97.3% accuracy in the Evening and investigate how the same conditions hinder accuracy for other scanning sessions. Revealing differences in functional brain networks based on extreme chronotype suggests future avenues of research that may ultimately better characterize the relationship between internal physiology, external perturbations, brain networks, and disease. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
30. Dynamic effective connectivity among large-scale brain networks mediates risk of anxiety.
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Tian Tian, Dong Liu, Guiling Zhang, Jian Wang, Changhua Wan, Jicheng Fang, Di Wu, Yiran Zhou, Yuanyuan Qin, Hongquan Zhu, Yuanhao Li, Chengxia Liu, Jiaxuan Zhang, Jia Li, and Wenzhen Zhu
- Subjects
- *
LARGE-scale brain networks , *ANXIETY , *DISEASE risk factors , *MONOGENIC & polygenic inheritance (Genetics) , *FUNCTIONAL magnetic resonance imaging - Abstract
Anxiety is characterized by altered brain networks. Directional information flows among dynamic brain networks concerning neuropathogenesis of anxiety have not yet been investigated. The role of directional influences between networks in gene--environment effects on anxiety remains to be further elucidated. In a large community sample, this resting-state functional MRI study estimated dynamic effective connectivity among large-scale brain networks based on a sliding-window approach and Granger causality analysis, providing dynamic and directional information for signal transmission in networks. We first explored altered effective connectivity among networks related to anxiety in distinct connectivity states. Due to the potential gene--environment effects on brain and anxiety, we further performed mediation and moderated mediation analyses to investigate the role of altered effective connectivity networks in relationships between polygenic risk scores, childhood trauma, and anxiety. State and trait anxiety scores showed correlations with altered effective connectivity among extensive networks in distinct connectivity states (p < .05, uncorrected). Only in a more frequent and strongly connected state, there were significant correlations between altered effective connectivity networks and trait anxiety (PFDR <0.05). Furthermore, mediation and moderated mediation analyses showed that the effective connectivity networks played a mediating role in the effects of childhood trauma and polygenic risk on trait anxiety. State-dependent effective connectivity changes among brain networks were significantly related to trait anxiety, and mediated gene--environment effects on trait anxiety. Our work sheds novel light on the neurobiological mechanisms underlying anxiety, and provides new insights into early objective diagnosis and intervention evaluation. [ABSTRACT FROM AUTHOR]
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- 2023
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31. Mechanistic insights into the interactions between cancer drivers and the tumour immune microenvironment.
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Misetic, Hrvoje, Keddar, Mohamed Reda, Jeannon, Jean-Pierre, and Ciccarelli, Francesca D.
- Subjects
- *
TUMOR microenvironment , *HEAD & neck cancer , *PROGRAMMED cell death 1 receptors - Abstract
Background: The crosstalk between cancer and the tumour immune microenvironment (TIME) has attracted significant interest in the latest years because of its impact on cancer evolution and response to treatment. Despite this, cancer-specific tumour-TIME interactions and their mechanistic insights are still poorly understood. Methods: Here, we compute the significant interactions occurring between cancer-specific genetic drivers and five anti- and pro-tumour TIME features in 32 cancer types using Lasso regularised ordinal regression. Focusing on head and neck squamous cancer (HNSC), we rebuild the functional networks linking specific TIME driver alterations to the TIME state they associate with. Results: The 477 TIME drivers that we identify are multifunctional genes whose alterations are selected early in cancer evolution and recur across and within cancer types. Tumour suppressors and oncogenes have an opposite effect on the TIME and the overall anti-tumour TIME driver burden is predictive of response to immunotherapy. TIME driver alterations predict the immune profiles of HNSC molecular subtypes, and perturbations in keratinization, apoptosis and interferon signalling underpin specific driver-TIME interactions. Conclusions: Overall, our study delivers a comprehensive resource of TIME drivers, gives mechanistic insights into their immune-regulatory role, and provides an additional framework for patient prioritisation to immunotherapy. The full list of TIME drivers and associated properties are available at http://www.network-cancer-genes.org. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
32. Understanding small-scale COVID-19 transmission dynamics with the Granger causality test.
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Romero García, Carolina, Briz-Redón, Álvaro, Iftimi, Adina, Lozano, Manuel, De Andrés, José, Landoni, Giovanni, and Zanin, Massimiliano
- Subjects
- *
GRANGER causality test , *INFECTIOUS disease transmission , *SUBWAY stations , *HEALTH facilities , *COVID-19 - Abstract
Mobility patterns have been broadly studied and deeply altered due to the coronavirus disease (COVID-19). In this paper, we study small-scale COVID-19 transmission dynamics in the city of Valencia and the potential role of subway stations and healthcare facilities in this transmission. A total of 2,398 adult patients were included in the analysis. We study the temporal evolution of the pandemic during the first six months at a small-area level. Two Voronoi segmentations of the city (based on the location of subway stations and healthcare facilities) have been considered, and we have applied the Granger causality test at the Voronoi cell level, considering both divisions of the study area. Considering the output of this approach, the so-called 'donor stations' are subway stations that have sent more connections than they have received and are mainly located in interchanger stations. The transmission in primary healthcare facilities showed a heterogeneous pattern. Given that subway interchange stations receive many cases from other regions of the city, implementing isolation measures in these areas might be beneficial for the reduction of transmission. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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33. Transcriptomic Analysis of Acetaminophen Biodegradation by Penicillium chrysogenum var. halophenolicum and Insights into Energy and Stress Response Pathways.
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Enguita, Francisco J., Pereira, Sofia, and Leitão, Ana Lúcia
- Subjects
- *
PENICILLIUM chrysogenum , *TRANSCRIPTOMES , *EXTRACELLULAR enzymes , *ENDOENZYMES , *ACETAMINOPHEN , *AMIDASES - Abstract
(1) Background: Acetaminophen (APAP), an active component of many analgesic and antipyretic drugs, is one of the most concerning trace contaminants in the environment and is considered as an emergent pollutant of marine and aquatic ecosystems. Despite its biodegradability, APAP has become a recalcitrant compound due to the growth of the global population, the ease of availability, and the inefficient wastewater treatment applied. (2) Methods: In this study, we used a transcriptomic approach to obtain functional and metabolic insights about the metabolization of APAP by a phenol-degrading fungal strain, Penicillium chrysogenum var. halophenolicum. (3) Results: We determined that the transcriptomic profile exhibited by the fungal strain during APAP degradation was very dynamic, being characterized by an abundance of dysregulated transcripts which were proportional to the drug metabolization. Using a systems biology approach, we also inferred the protein functional interaction networks that could be related to APAP degradation. We proposed the involvement of intracellular and extracellular enzymes, such as amidases, cytochrome P450, laccases, and extradiol-dioxygenases, among others. (4) Conclusions: Our data suggested that the fungus could metabolize APAP via a complex metabolic pathway, generating nontoxic metabolites, which demonstrated its potential in the bioremediation of this drug. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
34. Multi-head Attention-Based Masked Sequence Model for Mapping Functional Brain Networks
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He, Mengshen, Hou, Xiangyu, Wang, Zhenwei, Kang, Zili, Zhang, Xin, Qiang, Ning, Ge, Bao, Goos, Gerhard, Founding Editor, Hartmanis, Juris, Founding Editor, Bertino, Elisa, Editorial Board Member, Gao, Wen, Editorial Board Member, Steffen, Bernhard, Editorial Board Member, Yung, Moti, Editorial Board Member, Wang, Linwei, editor, Dou, Qi, editor, Fletcher, P. Thomas, editor, Speidel, Stefanie, editor, and Li, Shuo, editor
- Published
- 2022
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35. Generalized Quasi-Orthogonal Functional Networks Applied in Parameter Sensitivity Analysis of Complex Dynamical Systems
- Author
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Sasa S. Nikolic, Dragan S. Antic, Nikola B. Dankovic, Aleksandra A. Milovanovic, Darko B. Mitic, Miroslav B. Milovanovic, and Petar S. Djekic
- Subjects
orthogonal polynomials ,sensitivity analysis ,functional networks ,tower crane ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 - Abstract
This paper presents one possible application of generalized quasi-orthogonal functional networks in the sensitivity analysis of complex dynamical systems. First, a new type of first order (k = 1) generalized quasi-orthogonal polynomials of Legendre type via classical quasi-orthogonal polynomials was introduced. The short principle to design generalized quasi-orthogonal polynomials and filters was also shown. A generalized quasi-orthogonal functional network represents an extension of classical orthogonal functional networks and neural networks, which deal with general functional models. A sequence of the first order (k = 1) generalized quasi-orthogonal polynomials was used as a new basis in the proposed generalized quasi-orthogonal functional networks. The proposed method for determining the parameter sensitivity of complex dynamical systems is also given, and an example of a complex industrial system in the form of a tower crane was considered. The results obtained have been compared with different methods for parameter sensitivity analysis.
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- 2022
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36. Sampling bias and the robustness of ecological metrics for plant–damage‐type association networks.
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Swain, Anshuman, Azevedo‐Schmidt, Lauren E., Maccracken, S. Augusta, Currano, Ellen D., Dunne, Jennifer A., Labandeira, Conrad C., and Fagan, William F.
- Subjects
- *
BIPARTITE graphs , *GEOLOGICAL time scales , *ECOLOGICAL disturbances , *INSECT-plant relationships , *SAMPLE size (Statistics) , *PALEOECOLOGY - Abstract
Plants and their insect herbivores have been a dominant component of the terrestrial ecological landscape for the past 410 million years and feature intricate evolutionary patterns and co‐dependencies. A complex systems perspective allows for both detailed resolution of these evolutionary relationships as well as comparison and synthesis across systems. Using proxy data of insect herbivore damage (denoted by the damage type or DT) preserved on fossil leaves, functional bipartite network representations provide insights into how plant–insect associations depend on geological time, paleogeographical space, and environmental variables such as temperature and precipitation. However, the metrics measured from such networks are prone to sampling bias. Such sensitivity is of special concern for plant–DT association networks in paleontological settings where sampling effort is often severely limited. Here, we explore the sensitivity of functional bipartite network metrics to sampling intensity and identify sampling thresholds above which metrics appear robust to sampling effort. Across a broad range of sampling efforts, we find network metrics to be less affected by sampling bias and/or sample size than richness metrics, which are routinely used in studies of fossil plant–DT interactions. These results provide reassurance that cross‐comparisons of plant–DT networks offer insights into network structure and function and support their widespread use in paleoecology. Moreover, these findings suggest novel opportunities for using plant–DT networks in neontological terrestrial ecology to understand functional aspects of insect herbivory across geological time, environmental perturbations, and geographic space. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
37. General psychopathology factor (p-factor) prediction using resting-state functional connectivity and a scanner-generalization neural network.
- Author
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Hong, Jinwoo, Hwang, Jundong, and Lee, Jong-Hwan
- Subjects
- *
FUNCTIONAL connectivity , *FUNCTIONAL magnetic resonance imaging , *CHILD Behavior Checklist , *EXPLORATORY factor analysis , *ARTIFICIAL neural networks - Abstract
The general psychopathology factor (p -factor) represents shared variance across mental disorders based on psychopathologic symptoms. The Adolescent Brain Cognitive Development (ABCD) Study offers an unprecedented opportunity to investigate functional networks (FNs) from functional magnetic resonance imaging (fMRI) associated with the psychopathology of an adolescent cohort (n > 10,000). However, the heterogeneities associated with the use of multiple sites and multiple scanners in the ABCD Study need to be overcome to improve the prediction of the p -factor using fMRI. We proposed a scanner-generalization neural network (SGNN) to predict the individual p -factor by systematically reducing the scanner effect for resting-state functional connectivity (RSFC). We included 6905 adolescents from 18 sites whose fMRI data were collected using either Siemens or GE scanners. The p -factor was estimated based on the Child Behavior Checklist (CBCL) scores available in the ABCD study using exploratory factor analysis. We evaluated the Pearson's correlation coefficients (CCs) for p -factor prediction via leave-one/two-site-out cross-validation (LOSOCV/LTSOCV) and identified important FNs from the weight features (WFs) of the SGNN. The CCs were higher for the SGNN than for alternative models when using both LOSOCV (0.1631 ± 0.0673 for the SGNN vs. 0.1497 ± 0.0710 for kernel ridge regression [KRR]; p < 0.05 from a two-tailed paired t -test) and LTSOCV (0.1469 ± 0.0381 for the SGNN vs. 0.1394 ± 0.0359 for KRR; p = 0.01). It was found that (a) the default-mode and dorsal attention FNs were important for p -factor prediction, and (b) the intra-visual FN was important for scanner generalization. We demonstrated the efficacy of our novel SGNN model for p -factor prediction while simultaneously eliminating scanner-related confounding effects for RSFC. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
38. Flexible patterns of information transfer in frustrated networks of phase oscillators.
- Author
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Khatami, Saideh, Bolhasani, Ehsan, Perc, Matjaž, and Valizadeh, Alireza
- Abstract
Brain networks are characterized by flexible patterns of pairwise correlations and information exchange between different brain regions. Such dynamic patterns are crucial for an efficient response of the brain to environmental and cognitive demands. We here propose that the collective oscillations in the brain can provide a mechanism to control dynamical interactions and the exchange of information across brain networks. In particular, we show that the phase difference between oscillatory activities in different brain regions determines the transmission of neural signals. To further corroborate this, we study a network of coupled oscillators with repulsive couplings and show that the amount of information transfer between the nodes is determined by the phase differences. The emergence of multiple (locally) stable states due to the frustration makes it possible to change the patterns of information transfer between the nodes by means of the switching between different stable states. Our results indicate that frustration can be the mechanism through which large-scale brain networks control the effective connectivity and the routes for the information transfer between different brain regions. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
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39. Anterior dorsal attention network tau drives visual attention deficits in posterior cortical atrophy.
- Author
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Katsumi, Yuta, Putcha, Deepti, Eckbo, Ryan, Wong, Bonnie, Quimby, Megan, McGinnis, Scott, Touroutoglou, Alexandra, and Dickerson, Bradford C
- Subjects
- *
LARGE-scale brain networks , *CEREBRAL atrophy , *TAU proteins , *NEUROFIBRILLARY tangles , *ALZHEIMER'S disease , *CHRONIC traumatic encephalopathy , *CEREBRAL cortex - Abstract
Posterior cortical atrophy (PCA), usually an atypical clinical syndrome of Alzheimer's disease, has well-characterized patterns of cortical atrophy and tau deposition that are distinct from typical amnestic presentations of Alzheimer's disease. However, the mechanisms underlying the cortical spread of tau in PCA remain unclear. Here, in a sample of 17 biomarker-confirmed (A+/T+/N+) individuals with PCA, we sought to identify functional networks with heightened vulnerability to tau pathology by examining the cortical distribution of elevated tau as measured by 18F-flortaucipir (FTP) PET. We then assessed the relationship between network-specific FTP uptake and visuospatial cognitive task performance. As predicted, we found consistent and prominent localization of tau pathology in the dorsal attention network and visual network of the cerebral cortex. Elevated FTP uptake within the dorsal attention network (particularly the ratio of FTP uptake between the anterior and posterior nodes) was associated with poorer visuospatial attention in PCA; associations were also identified in other functional networks, although to a weaker degree. Furthermore, using functional MRI data collected from each patient at wakeful rest, we found that a greater anterior-to-posterior ratio in FTP uptake was associated with stronger intrinsic functional connectivity between anterior and posterior nodes of the dorsal attention network. Taken together, we conclude that our cross-sectional marker of anterior-to-posterior FTP ratio could indicate tau propagation from posterior to anterior dorsal attention network nodes, and that this anterior progression occurs in relation to intrinsic functional connectivity within this network critical for visuospatial attention. Our findings help to clarify the spatiotemporal pattern of tau propagation in relation to visuospatial cognitive decline and highlight the key role of the dorsal attention network in the disease progression of PCA. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
40. Recovery of Brain Network Integration and Segregation During the Loss and Recovery of Consciousness Induced by Sevoflurane.
- Author
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Dong, Kangli, Wei, Qishun, Zhang, Delin, Zhang, Lu, Wang, Guozheng, Chen, Xing, and Liu, Jun
- Subjects
LARGE-scale brain networks ,LOSS of consciousness ,SEVOFLURANE ,COMMUNITIES ,BRAIN anatomy - Abstract
Anesthetic-induced loss of consciousness (LOC) has been studied using functional connectivity (FC) and functional network analysis (FNA), manifested as fragmentation of the whole-brain functional network. However, how the fragmented brain networks reversibly recover during the recovery of consciousness (ROC) remains vague. This study aims to investigate the changes in brain network structure during ROC, to better understand the network fragmentation during anesthesia, thus providing insights into consciousness monitoring. We analyzed EEG data recorded from 15 individuals anesthetized by sevoflurane. By investigating the properties of functional networks generated using different brain atlases and performing community detection for functional networks, we explored the changes in brain network structure to understand how fragmented brain networks recover during the ROC. We observed an overall larger FC magnitude during LOC than in the conscious state. The ROC was accompanied by the increasing binary network efficiency, decreasing FC magnitude, and decreasing community similarity with the functional atlas. Furthermore, we observed a negative correlation between modularity and community number ($\text{p} < 0.001$ and $\textit {BF}_{{10}} >4000$ , linear regression test), in which modularity increased and community number decreased during ROC. Our results show that a larger FC magnitude reveals excessive synchronization of neuronal activities during LOC. The increasing binary network efficiency, decreasing community number, and decreasing community similarity indicate the recovery of functional network integration. The increasing modularity implies the recovery of functional network segregation during ROC. The results suggest the limitation of FC magnitude and modularity in monitoring anesthetized states and the potential of integrated information theory to evaluate consciousness. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
41. Classification of human chronotype based on fMRI network-based statistics
- Author
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Sophie L. Mason, Leandro Junges, Wessel Woldman, Elise R. Facer-Childs, Brunno M. de Campos, Andrew P. Bagshaw, and John R. Terry
- Subjects
chronotype (morningness-eveningness) ,functional connectivity ,fMRI ,classifier ,network-based statistical (NBS) analysis ,functional networks ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Chronotype—the relationship between the internal circadian physiology of an individual and the external 24-h light-dark cycle—is increasingly implicated in mental health and cognition. Individuals presenting with a late chronotype have an increased likelihood of developing depression, and can display reduced cognitive performance during the societal 9–5 day. However, the interplay between physiological rhythms and the brain networks that underpin cognition and mental health is not well-understood. To address this issue, we use rs-fMRI collected from 16 people with an early chronotype and 22 people with a late chronotype over three scanning sessions. We develop a classification framework utilizing the Network Based-Statistic methodology, to understand if differentiable information about chronotype is embedded in functional brain networks and how this changes throughout the day. We find evidence of subnetworks throughout the day that differ between extreme chronotypes such that high accuracy can occur, describe rigorous threshold criteria for achieving 97.3% accuracy in the Evening and investigate how the same conditions hinder accuracy for other scanning sessions. Revealing differences in functional brain networks based on extreme chronotype suggests future avenues of research that may ultimately better characterize the relationship between internal physiology, external perturbations, brain networks, and disease.
- Published
- 2023
- Full Text
- View/download PDF
42. Editorial: Interaction between affect and memory in the brain: From basic mechanisms to clinical implications
- Author
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Yuta Katsumi, Lycia D. de Voogd, Carlos Ventura-Bort, Wei Liu, and Shaozheng Qin
- Subjects
emotion ,episodic memory ,encoding ,consolidation ,retrieval ,functional networks ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Published
- 2023
- Full Text
- View/download PDF
43. Phase Analysis of Event-Related Potentials Based on Dynamic Mode Decomposition.
- Author
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Li, Li, Luo, Jingjing, Li, Yang, Zhang, Lei, and Guo, Yuzhu
- Subjects
- *
EVOKED potentials (Electrophysiology) , *BRAIN-computer interfaces , *ELECTROENCEPHALOGRAPHY , *TIME-frequency analysis , *HILBERT-Huang transform - Abstract
Real-time detection of event-related potentials (ERPs) and exploration of ERPs generation mechanisms are vital to practical application of brain–computer interfaces (BCI). Traditional methods for ERPs analysis often fall into time domain, time–frequency domain, or spatial domain. Methods which can reveal spatiotemporal interactions by simultaneously analyzing multi-channel EEG signals may provide new insights into ERP research and is highly desired. Additionally, although phase information has been investigated to describe the phase consistency of a certain frequency component across different ERP trials, it is of research significance to analyze the phase reorganization across different frequency components that constitute a single-trial ERP signal. To address these problems, dynamic mode decomposition (DMD) was applied to decompose multi-channel EEG into a series of spatial–temporal coherent DMD modes, and a new metric, called phase variance distribution (PVD) is proposed as an index of the phase reorganization of DMD modes during the ERP in a single trial. Based on the PVD, a new error-related potential (ErrP) detection method based on symmetric positive defined in Riemann manifold is proposed to demonstrate the significant PVD differences between correct and error trials. By including the phase reorganization index, the 10-fold cross-validation results of an ErrP detection task showed that the proposed method is 4.98%, 27.99% and 7.98% higher than the counterpart waveform-based ErrP detection method in the terms of weighted accuracy rate, precision and recall of the ErrP class, respectively. The resulting PVD curve shows that with the occurrence of ERP peaks, the phases of different frequency rhythms are getting to aligned and yields a significant smaller PVD. Since the DMD modes of different frequencies characterize spatiotemporal coherence of multi-channel EEG at different functional regions, the new phase reorganization index, PVD, may indicate the instantaneous phase alignment of different functional networks and sheds light on a new interpretation of ERP generation mechanism. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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44. Multi-compartment diffusion magnetic resonance imaging models link tract-related characteristics with working memory performance in healthy older adults.
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Bauer, Christopher E., Zachariou, Valentinos, Maillard, Pauline, Caprihan, Arvind, and Gold, Brian T.
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EXECUTIVE function ,MAGNETIC resonance imaging ,SHORT-term memory ,OLD age - Abstract
Multi-compartment diffusion MRI metrics [such as metrics from free water elimination diffusion tensor imaging (FWE-DTI) and neurite orientation dispersion and density imaging (NODDI)] may reflect more specific underlying white-matter tract characteristics than traditional, single-compartment metrics [i.e., metrics from Diffusion Tensor Imaging (DTI)]. However, it remains unclear if multi-compartment metrics are more closely associated with age and/or cognitive performance than single-compartment metrics. Here we compared the associations of single-compartment [Fractional Anisotropy (FA)] and multi-compartment diffusion MRI metrics [FWE-DTI metrics: Free Water Eliminated Fractional Anisotropy (FWE-FA) and Free Water (FW); NODDI metrics: Intracellular Volume Fraction (ICVF), Orientation Dispersion Index (ODI), and CSF-Fraction] with both age and working memory performance. A functional magnetic resonance imaging (fMRI) guided, white matter tractography approach was employed to compute diffusion metrics within a network of tracts connecting functional regions involved in working memory. Ninety-nine healthy older adults (aged 60-85) performed an in-scanner working memory task while fMRI was performed and also underwent multishell diffusion acquisition. The network of white matter tracts connecting functionally-activated regions was identified using probabilistic tractography. Diffusion metrics were extracted from skeletonized white matter tracts connecting fMRI activation peaks. Diffusion metrics derived from both single and multi-compartment models were associated with age (p
s ≤ 0.011 for FA, FWE-FA, ICVF and ODI). However, only multi-compartment metrics, specifically FWE-FA (p = 0.045) and ICVF (p = 0.020), were associated with working memory performance. Our results suggest that while most current diffusion metrics are sensitive to age, several multi-compartment metrics (i.e., FWE-FA and ICVF) appear more sensitive to cognitive performance in healthy older adults. [ABSTRACT FROM AUTHOR]- Published
- 2022
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45. Closing the mechanistic gap: the value of microarchitecture in understanding cognitive networks.
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Paquola, Casey, Amunts, Katrin, Evans, Alan, Smallwood, Jonathan, and Bernhardt, Boris
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DEFAULT mode network , *COGNITIVE neuroscience , *PARALLEL processing , *MIND-wandering - Abstract
Cognitive neuroscience aims to provide biologically relevant accounts of cognition. Contemporary research linking spatial patterns of neural activity to psychological constructs describes 'where' hypothesised functions occur, but not 'how' these regions contribute to cognition. Technological, empirical, and conceptual advances allow this mechanistic gap to be closed by embedding patterns of functional activity in macro- and microscale descriptions of brain organisation. Recent work on the default mode network (DMN) and the multiple demand network (MDN), for example, highlights a microarchitectural landscape that may explain how activity in these networks integrates varied information, thus providing an anatomical foundation that will help to explain how these networks contribute to many different cognitive states. This perspective highlights emerging insights into how microarchitecture can constrain network accounts of human cognition. Characterising the mechanisms of human cognition can benefit from integrating local microstructural properties with the macroscale organisation of the brain. Digitised datasets of the human brain, including histology, brain maps, transcriptomics, and high-resolution imaging, provide unprecedented opportunities to link microarchitectural features to functional networks that contribute to complex thought. Microarchitectural heterogeneity of higher cognitive networks [e.g., the default mode network (DMN) and multiple demand network (MDN)] underpins their broad involvements in cognition. The positioning of the DMN and the MDN with respect to hierarchical and parallel processing streams supports and sheds light onto their functional differences. Complex functional dynamics and the inter-relationship between functional networks may be better understood by taking a multidimensional perspective informed by changes in local microarchitecture. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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46. A study of brain functional network and alertness changes in temporal lobe epilepsy with and without focal to bilateral tonic–clonic seizures
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Liluo Nie, Yanchun Jiang, Zongxia Lv, Xiaomin Pang, Xiulin Liang, Weiwei Chang, and Jinou Zheng
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Temporal lobe epilepsy ,Graph theory ,Functional networks ,Focal to bilateral tonic-clonic seizures ,Alertness ,Neurology. Diseases of the nervous system ,RC346-429 - Abstract
Abstract Background Temporal lobe epilepsy (TLE) is commonly refractory. Epilepsy surgery is an effective treatment strategy for refractory epilepsy, but patients with a history of focal to bilateral tonic-clonic seizures (FBTCS) have poor outcomes. Previous network studies on epilepsy have found that TLE and idiopathic generalized epilepsy with generalized tonic-clonic seizures (IGE-GTCS) showed altered global and nodal topological properties. Alertness deficits also were found in TLE. However, FBTCS is a common type of seizure in TLE, and the implications for alertness as well as the topological rearrangements associated with this seizure type are not well understood. Methods We obtained rs-fMRI data and collected the neuropsychological assessment data from 21 TLE patients with FBTCS (TLE- FBTCS), 18 TLE patients without FBTCS (TLE-non- FBTCS) and 22 controls, and constructed their respective functional brain networks. The topological properties were analyzed using the graph theoretical approach and correlations between altered topological properties and alertness were analyzed. Results We found that TLE-FBTCS patients showed more serious impairment in alertness effect, intrinsic alertness and phasic alertness than the patients with TLE-non-FBTCS. They also showed significantly higher small-worldness, normalized clustering coefficient (γ) and a trend of higher global network efficiency (gE) compared to TLE-non-FBTCS patients. The gE showed a significant negative correlation with intrinsic alertness for TLE-non-FBTCS patients. Conclusion Our findings show different impairments in brain network information integration, segregation and alertness between the patients with TLE-FBTCS and TLE-non-FBTCS, demonstrating that impairments of the brain network may underlie the disruptions in alertness functions.
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- 2022
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47. Unveiling the core functional networks of cognition: An ontology-guided machine learning approach.
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Wu, Guowei, Cui, Zaixu, Wang, Xiuyi, and Du, Yi
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LARGE-scale brain networks , *COGNITION , *FUNCTIONAL connectivity , *MACHINE learning , *GENE expression profiling - Abstract
• A novel machine learning approach, the Cognitive Ontology-Based Prediction Model (COPM), was developed to isolate the core functional connectivity (FC) connectome representing cognition in the human brain. • The stable core FC connectome not only accurately predicts cognitive ontology scores but also efficiently forecasts a wide array of cognitive behaviors, demonstrating its robustness and applicability across various cognitive domains. • FC edges within the core FC connectome exhibit a high degree of variability in FC strength, strong structural connectivity (SC), and closely matched gene expression profiles, suggesting a potential genetic basis and enhanced neural adaptability for cognitive functions. Deciphering the functional architecture that underpins diverse cognitive functions is fundamental quest in neuroscience. In this study, we employed an innovative machine learning framework that integrated cognitive ontology with functional connectivity analysis to identify brain networks essential for cognition. We identified a core assembly of functional connectomes, primarily located within the association cortex, which showed superior predictive performance compared to two conventional methods widely employed in previous research across various cognitive domains. Our approach achieved a mean prediction accuracy of 0.13 across 16 cognitive tasks, including working memory, reading comprehension, and sustained attention, outperforming the traditional methods' accuracy of 0.08. In contrast, our method showed limited predictive power for sensory, motor, and emotional functions, with a mean prediction accuracy of 0.03 across 9 relevant tasks, slightly lower than the traditional methods' accuracy of 0.04. These cognitive connectomes were further characterized by distinctive patterns of resting-state functional connectivity, structural connectivity via white matter tracts, and gene expression, highlighting their neurogenetic underpinnings. Our findings reveal a domain-general functional network fingerprint that pivotal to cognition, offering a novel computational approach to explore the neural foundations of cognitive abilities. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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48. Brain Morphological and Functional Networks: Implications for Neurodegeneration
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Vuksanović, Vesna, Abarbanel, Henry D. I., Series Editor, Braha, Dan, Series Editor, Érdi, Péter, Series Editor, Friston, Karl J., Series Editor, Haken, Hermann, Series Editor, Jirsa, Viktor, Series Editor, Kacprzyk, Janusz, Series Editor, Kaneko, Kunihiko, Series Editor, Kelso, Scott, Founding Editor, Kirkilionis, Markus, Series Editor, Kurths, Jürgen, Series Editor, Menezes, Ronaldo, Series Editor, Nowak, Andrzej, Series Editor, Qudrat-Ullah, Hassan, Series Editor, Reichl, Linda, Series Editor, Schuster, Peter, Series Editor, Schweitzer, Frank, Series Editor, Sornette, Didier, Series Editor, Thurner, Stefan, Series Editor, Stefanovska, Aneta, editor, and McClintock, Peter V. E., editor
- Published
- 2021
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49. Functional Networks for Image Segmentation of Cutaneous Lesions with Rational Curves
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Gálvez, Akemi, Fister, Iztok, Fister, Iztok, Jr., Iglesias, Andrés, Kacprzyk, Janusz, Series Editor, Pal, Nikhil R., Advisory Editor, Bello Perez, Rafael, Advisory Editor, Corchado, Emilio S., Advisory Editor, Hagras, Hani, Advisory Editor, Kóczy, László T., Advisory Editor, Kreinovich, Vladik, Advisory Editor, Lin, Chin-Teng, Advisory Editor, Lu, Jie, Advisory Editor, Melin, Patricia, Advisory Editor, Nedjah, Nadia, Advisory Editor, Nguyen, Ngoc Thanh, Advisory Editor, Wang, Jun, Advisory Editor, Herrero, Álvaro, editor, Cambra, Carlos, editor, Urda, Daniel, editor, Sedano, Javier, editor, Quintián, Héctor, editor, and Corchado, Emilio, editor
- Published
- 2021
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50. Artificial Intelligence Models for Real-Time Bulk Density Prediction of Vertical Complex Lithology Using the Drilling Parameters.
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Ahmed, Ashraf, Elkatatny, Salaheldin, Gamal, Hany, and Abdulraheem, Abdulazeez
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ARTIFICIAL intelligence , *PETROLOGY , *SUPPORT vector machines , *RANDOM forest algorithms , *DENSITY - Abstract
Practically, the rock bulk density is measured either through logging while drilling tools or wireline logging techniques. However, these measurements are not always available, which necessitates using different empirical correlations. But these correlations have considerable limitations, which restricted their reliability and accuracy. This work aims to develop several artificial intelligence models for real-time bulk density prediction of complex lithology while drilling. The support vector machine (SVM), functional networks (FN), and random forest (RF) techniques were applied using the drilling parameters as inputs. A vertical well of 2912 data points of complex lithology containing sand, shale, and carbonate was used for model development. The developed models were validated using different dataset from another well. The results demonstrated that the three developed models predicted the bulk density with high matching accuracy. The SVM approach gives correlation coefficient (R) values of 0.999 and 0.984 and average absolute percentage error (AAPE) values of 0.113 and 0.512% in training and testing processes. The FN technique has R values of 0.980 and 0.979 and AAPE of 1.115 and 1.163%, while the RF-based model results in R values of 0.996 and 0.992 and AAPE values of 0.453 and 0.635% for training and testing, respectively. The validation process indicated the reliability and robustness of the constructed models with R values of 0.992, 0.977, and 0.990 and AAPE of 0.366, 1.224, and 0.733% for SVM, FN, and RF approaches, respectively. Each developed model can predict inexpensively the bulk density for multiple lithology types in real-time at high matching accuracy. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
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