graph theory analysis
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2022 ◽  
Vol 15 ◽  
Author(s):  
Wenzhuo Cui ◽  
Shanshan Wang ◽  
Boyu Chen ◽  
Guoguang Fan

Functional magnetic resonance imaging (fMRI) studies have suggested that there is a functional reorganization of brain areas in patients with sensorineural hearing loss (SNHL). Recently, graph theory analysis has brought a new understanding of the functional connectome and topological features in central neural system diseases. However, little is known about the functional network topology changes in SNHL patients, especially in infants. In this study, 34 infants with profound bilateral congenital SNHL and 28 infants with normal hearing aged 11–36 months were recruited. No difference was found in small-world parameters and network efficiency parameters. Differences in global and nodal topologic organization, hub distribution, and whole-brain functional connectivity were explored using graph theory analysis. Both normal-hearing infants and SNHL infants exhibited small-world topology. Furthermore, the SNHL group showed a decreased nodal degree in the bilateral thalamus. Six hubs in the SNHL group and seven hubs in the normal-hearing group were identified. The left middle temporal gyrus was a hub only in the SNHL group, while the right parahippocampal gyrus and bilateral temporal pole were hubs only in the normal-hearing group. Functional connectivity between auditory regions and motor regions, between auditory regions and default-mode-network (DMN) regions, and within DMN regions was found to be decreased in the SNHL group. These results indicate a functional reorganization of brain functional networks as a result of hearing loss. This study provides evidence that functional reorganization occurs in the early stage of life in infants with profound bilateral congenital SNHL from the perspective of complex networks.


2022 ◽  
Author(s):  
Shuting Yan ◽  
Qiyao Zhu ◽  
Swati Jain ◽  
Tamar Schlick

Abstract Conserved SARS-CoV-2 RNA regions of critical biological functions define excellent targets for anti-viral therapeutics against Covid-19 variants. One such region is the frameshifting element (FSE), responsible for correct translation of viral polyproteins. Here, we analyze molecular-dynamics motions of three FSE conformations, discovered by graph-theory analysis, and associated mutants designed by graph-based inverse folding: two distinct 3-stem H-type pseudoknots and a 3-way junction. We find that the prevalent H-type pseudoknot in literature adopts ring-like conformations, which in combination with 5′ end threading could promote ribosomal pausing. An inherent shape switch from “L” to linear that may help trigger the frameshifting is suppressed in our designed mutant. The alternative conformation trajectories suggest a stable intermediate structure with mixed stem interactions of all three conformations, pointing to a possible transition pathway during ribosomal translation. These observations provide new insights into anti-viral strategies and frameshifting mechanisms.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Elaina Atherton ◽  
Sophie Brown ◽  
Emily Papiez ◽  
Maria I. Restrepo ◽  
David A. Borton

AbstractThree-dimensional (3D) neural microtissues are a powerful in vitro paradigm for studying brain development and disease under controlled conditions, while maintaining many key attributes of the in vivo environment. Here, we used primary cortical microtissues to study the effects of neuroinflammation on neural microcircuits. We demonstrated the use of a genetically encoded calcium indicator combined with a novel live-imaging platform to record spontaneous calcium transients in microtissues from day 14–34 in vitro. We implemented graph theory analysis of calcium activity to characterize underlying functional connectivity and community structure of microcircuits, which are capable of capturing subtle changes in network dynamics during early disease states. We found that microtissues cultured for 34 days displayed functional remodeling of microcircuits and that community structure strengthened over time. Lipopolysaccharide, a neuroinflammatory agent, significantly increased functional connectivity and disrupted community structure 5–9 days after exposure. These microcircuit-level changes have broad implications for the role of neuroinflammation in functional dysregulation of neural networks.


2021 ◽  
Author(s):  
Jing Ren ◽  
Qun Yao ◽  
Minjie Tian ◽  
Feng Li ◽  
Yueqiu Chen ◽  
...  

Abstract Background: Migraine is a common and disabling primary headache associated with a wide range of psychiatric comorbidities. However, the mechanisms of emotion processing in migraine are not fully understood yet. The present study was designed to investigate the neural network during neutral, positive,and negative emotional stimuli in migraine suffers.Methods: We enrolled 24 migraine suffers and 24 age- and sex-matched controls in this study. Neuromagnetic brain activity was recorded by using a whole-head magnetoencephalography (MEG) system towards human faces expression pictures. MEG data were analyzed in the multi-frequency band of 1–100 Hz.Results: Migraine patients exhibited significantly enhanced effective connectivity from the prefrontal lobe to the temporal cortex during negative emotional stimuli in the gamma band(30-90Hz). Graph theory analysis revealed that patients had (1) an increased degree and clustering coefficient of connectivity in the delta band(1-4Hz) during positive emotional stimuli; (2) an increased degree of connectivity in the delta band(1-4Hz) during negative emotional stimuli.Conclusion: The results suggested individuals with migraine showed deviant effective connectivity when viewing human facial expressions in multi-frequency. The prefrontal-temporal pathway might be related to the altered negative emotion modulation in migraine. These findings may contribute to understanding the mechanism of the comorbidity of depression and anxiety in migraine and provide references for the comprehensive therapeutic plan.


2021 ◽  
Vol 11 (11) ◽  
pp. 1396
Author(s):  
Ermanno Quadrelli ◽  
Elisa Roberti ◽  
Silvia Polver ◽  
Hermann Bulf ◽  
Chiara Turati

The present study investigated whether, as in adults, 7-month-old infants’ sensorimotor brain areas are recruited in response to the observation of emotional facial expressions. Activity of the sensorimotor cortex, as indexed by µ rhythm suppression, was recorded using electroencephalography (EEG) while infants observed neutral, angry, and happy facial expressions either in a static (N = 19) or dynamic (N = 19) condition. Graph theory analysis was used to investigate to which extent neural activity was functionally localized in specific cortical areas. Happy facial expressions elicited greater sensorimotor activation compared to angry faces in the dynamic experimental condition, while no difference was found between the three expressions in the static condition. Results also revealed that happy but not angry nor neutral expressions elicited a significant right-lateralized activation in the dynamic condition. Furthermore, dynamic emotional faces generated more efficient processing as they elicited higher global efficiency and lower networks’ diameter compared to static faces. Overall, current results suggest that, contrarily to neutral and angry faces, happy expressions elicit sensorimotor activity at 7 months and dynamic emotional faces are more efficiently processed by functional brain networks. Finally, current data provide evidence of the existence of a right-lateralized activity for the processing of happy facial expressions.


2021 ◽  
Vol 15 ◽  
Author(s):  
Chengyuan Wu ◽  
Caio Matias ◽  
Thomas Foltynie ◽  
Patricia Limousin ◽  
Ludvic Zrinzo ◽  
...  

Background: Neuronal loss in Parkinson’s Disease (PD) leads to widespread neural network dysfunction. While graph theory allows for analysis of whole brain networks, patterns of functional connectivity (FC) associated with motor response to deep brain stimulation of the subthalamic nucleus (STN-DBS) have yet to be explored.Objective/Hypothesis: To investigate the distributed network properties associated with STN-DBS in patients with advanced PD.Methods: Eighteen patients underwent 3-Tesla resting state functional MRI (rs-fMRI) prior to STN-DBS. Improvement in UPDRS-III scores following STN-DBS were assessed 1 year after implantation. Independent component analysis (ICA) was applied to extract spatially independent components (ICs) from the rs-fMRI. FC between ICs was calculated across the entire time series and for dynamic brain states. Graph theory analysis was performed to investigate whole brain network topography in static and dynamic states.Results: Dynamic analysis identified two unique brain states: a relative hypoconnected state and a relative hyperconnected state. Time spent in a state, dwell time, and number of transitions were not correlated with DBS response. There were no significant FC findings, but graph theory analysis demonstrated significant relationships with STN-DBS response only during the hypoconnected state – STN-DBS was negatively correlated with network assortativity.Conclusion: Given the widespread effects of dopamine depletion in PD, analysis of whole brain networks is critical to our understanding of the pathophysiology of this disease. Only by leveraging graph theoretical analysis of dynamic FC were we able to isolate a hypoconnected brain state that contained distinct network properties associated with the clinical effects of STN-DBS.


Author(s):  
Mohammad Ali Taheri ◽  
Fatemeh Modarresi-Asem ◽  
Noushin Nabavi ◽  
Parisa Maftoun ◽  
Farid Semsarha

The study of the brain networks using analysis of electroencephalography (EEG) data based on statistical dependencies (functional connectivity) and mathematical graph theory concepts is common in neuroscience and cognitive sciences for examinations of patient and healthy individuals. The Consciousness Fields according to Taheri theory and applications in the optimization of system under study have been investigated in various studies. In this study, we examine the results of working with Faradarmani Consciousness Field (FCF) in the brain of Faradarmangars. Faradarmangars are one of the necessary components in mind mediation of the function of Faradarmani Consciousness Fields according to Taheri. For this purpose, the functional and effective connectivity and the corresponding brain graphs of EEG from the brain of Faradarmangars is compared with that of non Faradarmangar groups during FCF connection. According to the results of the present study, the brain of the Faradarmangars shows significant decreased activity in delta (BA8), beta2 (BA4/6/8/9/10/11/32/44/47) and beta3 (in 34 of 52 BA) frequency bands mainly in frontal lobe and after that in parietal and temporal lobes in the comparison with the non Faradarmangars. Moreover, the functional and effective connectivity analysis in the frontal network shows dominant multiple decreased connectivity mainly in the case of beta3 frequency band in all parts of the frontal network. On the other hand, the graph theory analysis of the Faradarmangar brain shows an increase in the activity of the O2-T5-F4-F3-FP2-F8 areas and significant decrease in the characteristic path length and increases in global efficiency, clustering coefficient and transitivity. In conclusion, the unique higher graph function efficiency and the reduction in the brain activity and connectivity during the Faradarmani Consciousness Field mind mediation, shown the passive and detector like function of the human brain in this task.


Forests ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1201
Author(s):  
Pablo J. Hidalgo ◽  
Helena Hernández ◽  
Antonio J. Sánchez-Almendro ◽  
Javier López-Tirado ◽  
Federico Vessella ◽  
...  

Habitat loss and fragmentation are considered some the main threats to biodiversity. Original forests have suffered an accentuated fragmentation and agricultural homogenization, leaving only some areas of natural vegetation, relegated to strongly anthropized disconnected patches (island forests, IFs) in a hostile matrix. These patches of original vegetation could be the key for the design and management of ecological corridors to promote species migration, an essential strategy for meeting the consequences of Global Change. This study proposes a comparative analysis of the fragmentation and connectivity of IFs of Quercus in two typically Mediterranean areas of predominantly agricultural use: the Guadalquivir valley (Spain) and the Apulia region (Italy). A retrospective comparison is also carried out in the Guadalquivir valley. The aim is to develop an objective new methodology to locate the patches of most interest using quantitative and qualitative data. Reference cartography of current island forests of Quercus species was developed from several digital sources and validated with orthoimages and field observations. Fragmentation analysis was based on graph structures using the software Conefor 2.6, a reliable tool for assessment of the role of patches in the landscape. Area and distance were used as node and connector values. Dispersion distance was established as 500 m, based on the maximum dispersion of acorns. Results indicate that the Guadalquivir valley has suffered an intensive fragmentation in recent decades. Both the Guadalquivir and Apulia regions host some IFs with the relevant potential to contribute as core habitats in the creation of connections to other natural protected sites. Many residual IFs in the landscape could contribute as stepping stones in the design and management of ecological corridors. Our methodology highlights the value of IFs to develop assessment strategies using homogenized available digital cartography and common criteria for the dispersion distances in graph theory analysis. The application of this new methodology could help in the management of protected sites using highly fragmented areas to allow the species movement through inhospitable landscapes in a unique opportunity to connect the different protected areas.


2021 ◽  
Author(s):  
Andres Ospina-Alvarez ◽  
Silvia de Juan Mohan ◽  
Pablo Pita ◽  
Gillian Ainsworth ◽  
Fabio Matos ◽  
...  

Abstract The global cephalopod trade is a multi-billion-dollar industry that involves fishing and captive breeding of a dozen species of high commercial value. It also contributes wholly or partly to the income and subsistence of thousands of families around the world. Despite its broad ecological, social, and economic importance, limited research has been conducted to describe the scope and scale of the global cephalopod trade. To date, there is no specific regulation, nor have tracking systems been implemented, to study the traceability of the global cephalopod trade at an international level. We provide, for the first time, a comprehensive description of the legal trade in cephalopods to understand who the key world players in the cephalopod seafood markets are. We analysed 20 years of records compiled by the United Nations COMTRADE database. The database contained 115,108 entries for squid and cuttlefish and 71,659 entries for octopus, including the product flow between traders (countries or territories) weighted by volume (kg) and monetary value (USD). Graph theoretic analysis was used to explore the emergent properties of this database through the analysis of different measures of centrality that provide insights on the key role of the traders in the network. Our findings show that most of the market movements between ca. 250 traders are led by three countries (China, Spain, and Japan), involving 11 clusters of traders based on the volume and value of cephalopod trade and number of transactions. The most important cluster, that dominates the cephalopod seafood market, is composed by 5 Asian countries (China, India, Republic of Korea, Thailand, and Vietnam), 2 European countries (the Netherlands and Spain) and the USA. This work identifies the traders that act as major exporters and/or importers, the modulators, intermediaries or accumulators, the best-connected traders, the principal flow routes and the weaknesses of the global cephalopod trade network. This network information is essential to advance towards a transparent and sustainable cephalopods world trade.


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