Дисертації з теми "Functional connectomes"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-25 дисертацій для дослідження на тему "Functional connectomes".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
Bollmann, Yannick. "Emergence of functional and structural cortical connectomes through the developmental prism." Thesis, Aix-Marseille, 2019. http://theses.univ-amu.fr.lama.univ-amu.fr/191113_BOLLMANN_844bezee521trbla166eo565zm_TH.pdf.
Повний текст джерелаCortical neurons are generated throughout an extended embryonic period. Recent studies indicate that the cells originating from the earliest stages of neurogenesis are critically involved in coordinating neuronal activity, instructing network maturation throughout large cortical areas. The first part of my work was building and mining brain cell atlases and connectomes. I first characterized the brain-wide structural connectome of early-born glutamatergic and GABAergic neurons, fluorescently labeled according to their date of birth (genetic fate-mapping approach). Using light-sheet microscopy on cleared brains, I quantify the distribution of both populations in the whole brain to create an Atlas.The second part of my work was the characterization of GABAergic neurons functional connectome and the characterization of hub cells in the developing barrel cortex in vivo. By using transgenic mice lines expressing the calcium indicator GCaMP6s, we follow the maturation and the functional dynamics of the network during the two first postnatal weeks using two-photon imaging. The characteristically heavy-tailed distribution of functional connections between neurons that we observed, strongly suggest the presence of hub neurons. Using two-photon calcium imaging and holographic-optogenetic stimulation we entangle the necessary and sufficient conditions of how GABAergic neurons contribute to and synchronize network activity as acting as hub neuron in the barrel cortex
Afyouni, Soroosh. "Application of graph theoretical models to the functional connectome of human brain." Thesis, University of Warwick, 2016. http://wrap.warwick.ac.uk/88528/.
Повний текст джерелаMahama, Edward Kofi. "Connectome eigenmodes underlies functional connectivity patterns in conscious awake and anesthetic mice." HKBU Institutional Repository, 2020. https://repository.hkbu.edu.hk/etd_oa/880.
Повний текст джерелаKundu, Prantik. "Physical analysis of BOLD fMRI signals for functional brain mapping and connectomics." Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648842.
Повний текст джерелаMelozzi, Francesca. "Simulated switching of the resting state functional connectivity in mouse brain using a real mesoscale connectome." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/8319/.
Повний текст джерелаMelozzi, Francesca. "The role of structural brain features on resting-state functional organization : a large-scale computational study in mice." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0771.
Повний текст джерелаThe connectome-based model approach aims to understand the functional organization of the brain by modeling the brain as a dynamical system and then studying how the functional architecture rises from the underlying structural skeleton. In this thesis, taking advantage of mice studies, we investigated the informative content of different structural features in explaining the functional ones.First, we extended the open-source software TVB (Leon et al., 2013), originally designed for humans, to accommodate the connectome-based model approach in mice (Melozzi et al., 2017).Using diffusionMRI (dMRI) data from 19 mice, we virtualised their brains to generate in silico fMRI that we compared to functional MRI data recorded in the same mice during passive wakefulness. We show that the predictions of the connectome-based model strictly depend on the structure of the underlying network (Melozzi et al., under review). We demonstrate that individual variations define a specific structural fingerprint with a direct impact upon the functional organization of individual brains. Comparing the predictive power of the tracer-based and the dMRI-based connectome we identify how the limitations of the dMRI method restrict our comprehension of the structural-functional relation. Together, these results strongly support the existence of a causal link between the structural and the functional connectomes.Finally, we infer the connectome form resting state dynamics by inferring the structural connectome using the Bayesian inference (Melozzi et al., in prep).Our results pave the way to future studies focusing on the causal link between structure and function at the individual brain level
Hart, Michael Gavin. "Network approaches to understanding the functional effects of focal brain lesions." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/274018.
Повний текст джерелаVáša, František. "Characterising disease-related and developmental changes in correlation-derived structural and functional brain networks." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/277816.
Повний текст джерелаColclough, Giles. "Methods for modelling human functional brain networks with MEG and fMRI." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:ef1dc66e-f142-4cdc-8177-5d040c94b964.
Повний текст джерелаSuprano, Ilaria. "Étude de la connectivité cérébrale par IRM fonctionnelle et de diffusion dans l’intelligence." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1282.
Повний текст джерелаThe idea that intelligence is embedded not only in specific brain regions, but also in efficient brain networks has grown up. Indeed, human brain organization is believed to rely on complex and dynamic networks in which the communication between cerebral regions guarantees an efficient transfer of information. These recent concepts have led us to explore the neural bases of intelligence using both advanced MRI techniques in combination with graph analysis. On one hand, advanced MRI techniques, such as resting-state functional MRI (rs-fMRI) and diffusion MRI (dMRI) allow the exploration of respectively the functional and the structural brain connectivity while on the other hand, graph theory models allow the characterization of brain networks properties at different scales, thanks to global and local metrics. The aim of this thesis is to characterize the topology of functional and structural brain networks in children and in adults with an intelligence quotient higher (HIQ) than standard levels (SIQ). First, we focused our attention on a children population with different cognitive characteristics. Two HIQ profiles, namely homogeneous (Hom-HIQ) and heterogeneous HIQ (Het-HIQ), have been defined based on clinical observations and Intelligence Quotient (IQ) sub-tests. Using resting-state fMRI techniques, we examined the functional network topology changes, estimating the "hub disruption index", in these two HIQ profiles. We found significant topological differences in the integration and segregation properties of brain networks in HIQ compared to SIQ children, for the whole brain graph, for each hemispheric graph, and for the homotopic connectivity. These brain networks changes resulted to be more pronounced in Het-HIQ subgroup. Finally, we found significant correlations between the graph networks’ changes and the full-scale IQ, as well as some intelligence subscales. These results demonstrated for the first time, that different HIQ profiles are related to a different neural substrate organization. Then, the structural brain network connectivity, measured by dMRI in all HIQ children, were significantly different than in SIQ children. Also, we found strong correlations between the children brain networks density and their intelligence scores. Furthermore, several correlations were found between integration graph metrics suggesting that intelligence performances are probably related to a homogeneous network organization. These findings demonstrated that intelligence neural substrate is based on a strong white matter microarchitecture of the major fiber-bundles and a well-balanced network organization between local and global scales. This children population was finally studied using a memory-word task of fMRI. Significant changes were observed between both HIQ and SIQ groups. This study confirms our hypothesis that both HIQ profiles are characterized by a different brain activity, with stronger evidences in Het-HIQ children. Finally, we investigated both functional and structural connectivity in a population of adults HIQ. We found several correlations between graph metrics and intelligence sub-scores. As well as for the children population, high cognitive abilities of adults seem to be related brain structural and functional networks organization with a decreased modularity. In conclusion, the sensitivity of graph metrics based on advanced MRI techniques, such as rs-fMRI and dMRI, was demonstrated to be very helpful to provide a better characterization of children and adult HIQ, and further, to distinguish different intelligence profiles in children
Papantoniou, Christos [Verfasser], Wolfgang [Akademischer Betreuer] Baumeister, Johannes [Gutachter] Buchner, and Wolfgang [Gutachter] Baumeister. "Presynaptic Tethers and Connectors: Molecular Composition and Functional Role / Christos Papantoniou ; Gutachter: Johannes Buchner, Wolfgang Baumeister ; Betreuer: Wolfgang Baumeister." München : Universitätsbibliothek der TU München, 2021. http://d-nb.info/1236343336/34.
Повний текст джерелаSalah, Eddin Anas. "Network Construction and Graph Theoretical Analysis of Functional Language Networks in Pediatric Epilepsy." FIU Digital Commons, 2013. http://digitalcommons.fiu.edu/etd/971.
Повний текст джерелаTowlson, Emma Katie. "Complex networks and connectomics : network analysis of organisation from the C. elegans nervous system to the functional connectivity of the human brain." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709453.
Повний текст джерелаPereira, Fabricio Ramos Silvestre 1975. "Conectoma cerebral = aplicações de imageamento por ressonância magnética nuclear em neurociências = Brain connectome : aplications of nuclear magnetic resonance imaging in neurosciences." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/312650.
Повний текст джерелаTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas
Made available in DSpace on 2018-08-24T17:19:19Z (GMT). No. of bitstreams: 1 Pereira_FabricioRamosSilvestre_D.pdf: 32802688 bytes, checksum: 367566b29c460e1b33f48f861845217a (MD5) Previous issue date: 2013
Resumo: O conectoma cerebral refere-se ao mapeamento dos circuitos neurais com os objetivos de 1) identificar regiões que dão suporte às atividades mentais e comportamentais, e 2) detectar alterações nesses circuitos que levam a distúrbios de ordem psiquiátrica e neurológica. Na prática, os estudos de conectoma cerebral consistem na integração de técnicas multimodais de imageamento como ressonância magnética (RM), eletroencefalograma (EEG) e magnetoencefalograma (MEG) com o intuito de estimar os tipos e os níveis de conexão entre regiões cerebrais remotas. Essa "conectividade" entre regiões cerebrais é geralmente classificada em três tipos: anatômica, funcional e efetiva. No presente trabalho, as técnicas de conectividade, usando dados de MR, foram aplicadas na comparação de grupos saudáveis e patológicos. Pela técnica de conectividade anatômica observou-se anomalias na substância branca de pacientes com mutação no gene SPG11. Essa anomalias foram detectadas através da redução da anisotropia fracional (FA) e aumento da difusividade média (MD), difusividade radial (RD) e difusividade axial (AD) em regiões subcorticais dos lobos temporal e frontal, bem como no giro do cíngulo, cuneus striatum, corpo caloso e tronco cerebral. Tais achados indicam que o dano neuronal é mais difuso do que indicava a literatura. Um segundo estudo de conectividade anatômica demonstrou que esses índices de difusividade não foram robustos para diferenciar idosos com e sem diagnóstico de depressão indicando a necessidade de avanços na formulação de novos índices com maior sensibilidade. A técnica de conectividade funcional foi empregada em três estudos. No primeiro, observou-se que pacientes com epilepsia de lobo temporal medial unilateral apresentam redução da conectividade funcional durante a execução de tarefas de memória verbal e visual. Essa redução foi predominantemente ipslateral à lesão e associada ao material-específico utilizado no teste de memória. No segundo estudo, verificou-se uma redução dos padrões de conectividade funcional hipotalâmica em sujeitos obesos e a sua parcial elevação após a cirurgia bariátrica concomitantemente à redução de indicadores bioquímicos de inflamação. No terceiro estudo, observou-se que pacientes com doença de Alzheimer apresentaram elevação dos níveis de conectividade funcional na rede saliente (Salience Network) e redução na rede de modo padrão (Default-mode network). Adicionalmente, verificou-se nos pacientes a correlação positiva da síndrome hiperativa com os níveis de conectividade funcional no cíngulo anterior e em áreas da ínsula direita. O conjunto desses resultados ilustra um possível significado clínico para futuro diagnóstico e tratamento da doença de Alzheimer. Pela técnica de conectividade efetiva observou-se que em função do envelhecimento sadio há uma mudança dos parâmetros de conectividade durante a codificação de palavras com conteúdo emocional. A influência do hipocampo sobre a amígdala ipslateral é reduzida nos sujeitos mais velhos enquanto a influência da amígdala direita sobre o hipocampo direito é elevada. Tais achados reforçam a tese da ininterrupta plasticidade etária e da dinâmica cerebral normal. Essa mesma técnica foi também empregada para demonstrar os diferentes padrões de influência entre os lobos frontal e temporal de pacientes com ELTM esquerda e sujeitos controle. Encontrou-se alteração nos padrões de conectividade efetiva dos pacientes, indicando que estes podem ser potenciais biomarcadores para a epilepsia
Abstract: Connectome refers to the neural circuitry mapping aiming to identify brain regions that support mental and behavioral functions as well as to detect circuit changes that are linked to psychiatric or neurologic disorders. In practice, connectome studies link several neuroimaging approaches such as MRI, EEG and MEG by means of the estimation of connections among remote brain regions. This "connectivity" among brain regions is usually classified as anatomic, functional or effective. In this work, the technique of connectivity, using MR data, was applied to compare healthy and pathological groups. By means of the anatomical connectivity abnormalities in the white matter of patients with SPG11 mutation were observed. These abnormalities were expressed as the reduction of the levels of fractional anisotropy (FA) and the increase in mean (MD) and radial diffusivities (RD) in sub-cortical regions of temporal and frontal lobe as well as in cingulated gyrus, cuneus, striatum, corpus callosum and brainstem. These findings suggest that neuronal damage/dysfunction is more widespread than previously recognized in this condition. Another anatomical connectivity study showed that such indices of diffusivity were not robust to statistically differentiate between old subjects with and without depression. This lacking on finding differences between both groups indicates that new indices of diffusivity have to emerge in order to provide complementary information about brain subtle microstructures. Functional connectivity was applied to three studies. In the first study, it was observed that patients with unilateral medial temporal lobe epilepsy presented lower levels of functional connectivity during visual or verbal memory tasks. Such reduction was ipsilateral to the side of the lesion and associated to the specific-material used in the memory task. In the second work, the levels of functional connectivity were reduced in hypothalamic regions of obese patients but a partial reversibility of hypothalamic dysfunction was observed after bariatric surgery. In the third, patients with Alzheimer disease presented higher values of functional connectivity in the salience network and a reduction of connectivity values in the default-mode network. Also in these patients, significant correlations between the levels of hyperactivity syndrome and the salience network were observed in the anterior cingulate cortex and right insula areas. These results indicate the potential clinical significance of resting state alterations in future diagnosis and therapy of Alzheimer disease. The effective connectivity approaches demonstrated that old and young subjects have significant differences when encoding words with emotional contents. The influence of the hippocampus on the ipsilateral amygdale was lower for older subjects whereas the influence of the right amygdale on the right hippocampus was increased for these subjects. These findings suggest that brain plasticity also happens as function of age. The same approach was used to estimate the influence from frontal to temporal lobes in patients with left MTLE compared to healthy subjects. The patterns of effective connectivity were changed in patients and may be potentially considered as biomarkers for epilepsy
Doutorado
Neurociencias
Doutor em Ciências
Díaz, Parra Antonio. "A network science approach of the macroscopic organization of the brain: analysis of structural and functional brain networks in health and disease." Doctoral thesis, Universitat Politècnica de València, 2018. http://hdl.handle.net/10251/106966.
Повний текст джерелаThe brain is composed of massively connected elements arranged into modules that form hierarchical networks. Experimental evidence reveals a well-defined connectivity design, characterized by the presence of strategically connected core nodes that critically contribute to resilience and maintain stability in interacting brain networks. Certain brain pathologies, such as Alzheimer's disease and alcohol use disorder, are thought to be a consequence of cascading maladaptive processes that alter normal connectivity. These findings have greatly contributed to the development of network neuroscience to understand the macroscopic organization of the brain. This thesis focuses on the application of network science tools to investigate structural and functional brain networks in health and disease. To accomplish this goal, three specific studies are conducted using human and rodent data recorded with MRI and tracing technologies. In the first study, we examine the relationship between structural and functional connectivity in the rat cortical network. Using a detailed cortical structural matrix obtained from published histological tracing data, we first compare structural connections in the rat cortex with their corresponding spontaneous correlations extracted empirically from fMRI data. We then show the results of this comparison by relating structural properties of brain connectivity to the functional modularity of resting-state networks. Specifically, we study link reciprocity in both intra- and inter-modular connections as well as the structural motif frequency spectrum within functionally defined modules. Overall, our results provide further evidence that structural connectivity is coupled to and shapes functional connectivity in cortical networks. The pathophysiological process of Alzheimer's disease is thought to begin years before clinical decline, with evidence suggesting pahtogenic seeding and subsequent prion-like spreading processes of neurofibrillary tangles and amyloid plaques. In the second study of this thesis, we investigate whether structural brain networks as measured with dMRI could serve as a complementary diagnostic tool in prodromal dementia. Using imaging data from the ADNI database, we first aim to implement machine learning techniques to extract centrality features that are altered in Alzheimer's dementia. We then incorporate data from the NKI database and create dynamical models of normal aging and Alzheimer's disease to estimate the earliest detectable stage associated with dementia in the simulated disease progression. Our model results suggest that changes associated with dementia begin to manifest structurally at early stages. Statistical dependence measures computed between BOLD signals can inform about brain functional states in studies of neurological and psychiatric disorders. Furthermore, its non-invasive nature allows comparable measurements between clinical and animal studies, providing excellent translational capabilities. In the last study, we apply the NBS method to investigate alterations in the resting-state functional connectivity of the rat brain in a PD state, an established animal model of clinical relevant features in alcoholism. The analysis reveal statistically significant differences in a connected subnetwork of structures with known relevance for addictive behaviors, hence suggesting potential targets for therapy. This thesis provides three novel contributions to understand the healthy and pathological brain connectivity under the perspective of network science. The results obtained in this thesis underscore that brain network models offer further insights into the structure-function coupling in the brain. More importantly, this network perspective provides potential applications for the diagnosis and treatment of neurological and psychiatric disorders.
El cervell està constituït per nombrosos elements que es troben interconnectats de forma massiva i organitzats en mòduls que formen xarxes jeràrquiques. Certes patologies cerebrals, com la malaltia d'Alzheimer i el trastorn per consum d'alcohol, es consideren el resultat d'efectes en cascada que alteren la connectivitat cerebral. La present tesi té com a objectiu principal l'aplicació de les tècniques d'anàlisi de la ciència de xarxes per a l'estudi de les xarxes estructurals i funcionals en el cervell, tant en un estat control com en un estat patològic. Així, en el primer estudi de la present tesi s'examina la relació entre la connectivitat estructural i funcional en l'escorça cerebral de la rata. Es du a terme una anàlisi comparativa entre les connexions estructurals en l'escorça cerebral de la rata i els valors de correlació calculats sobre les mateixes regions. La informació sobre la connectivitat estructural s'ha obtingut a partir d'estudis previs, mentre que la connectivitat funcional s'ha calculat a partir d'imatges de ressonància magnètica funcional. Determinades propietats topològiques, i extretes de la connectivitat estructural, es relacionen amb l'organització modular de les xarxes funcionals en estat de repòs. Els resultats obtinguts en este primer estudi demostren que la connectivitat estructural i funcional cortical estan altament relacionades entre si. Estudis recents suggereixen que l'origen de la malaltia d'Alzheimer resideix en un mecanisme en el qual depòsits d'ovulets neurofibrilars i plaques de beta- miloide s'acumulen en certes regions cerebrals, i tenen la capacitat de disseminar-se pel cervell actuant com a prions. En el segon estudi de la present tesi s'investiga si les xarxes estructurals que es generen amb la tècnica de la imatge per ressonància magnètica ponderada en difusió podrien ser d'utilitat per al diagnòstic de la predemència causada per la malaltia d'Alzheimer. Per mitjà de l'ús d'imatges procedents de la base de dades ADNI, s'apliquen tècniques d'aprenentatge màquina a fi d'identificar mesures de centralitat que es troben alterades en la demència. En la segona part de l'estudi, s'utilitzen imatges procedents de la base de dades NKI per a construir un model matemàtic que simule el procés d'envelliment normal, així com un altre model que simule el procés de desenrotllament de la malaltia. Amb este modelatge matemàtic, es pretén estimar l'etapa més primerenca que està associada amb la demència. Els resultats obtinguts de les simulacions suggereixen que en etapes primerenques de la malaltia d'Alzheimer es produeixen alteracions estructurals relacionats amb la demència. La quantificació de la relació estadística entre els senyals BOLD de diferents regions pot informar sobre l'estat funcional cerebral característic de malalties neurològiques i psiquiàtriques. A més, a causa de la seua naturalesa no invasiva, és possible comparar els resultats obtinguts entre estudis clínics i estudis amb animals d'experimentació. En el tercer estudi de la present tesi s'estudien les alteracions en la connectivitat funcional que tenen lloc en rates dependents del consum d'alcohol quan es troben en estat de repòs. Per a realitzar-ho, s'ha aplicat el mètode NBS. L'anàlisi d'aquest model de rata revela diferències estadísticament significatives en una subxarxa de regions cerebrals que estan implicades en comportaments addictius. Per tant, estes estructures cerebrals podrien ser el focus de possibles dianes terapèutiques. La tesi aporta tres innovadores contribucions per a entendre la connectivitat cerebral davall la perspectiva de la ciència de xarxes, tant en un estat control com en un estat patològic. Els resultats destaquen que els models basats en les xarxes cerebrals permeten aclarir la relació entre l'estructura i la funció en el cervell. I potser més important, esta perspectiva de xarxa té aplicacions que es podrien traslladar a la pràcti
Díaz Parra, A. (2018). A network science approach of the macroscopic organization of the brain: analysis of structural and functional brain networks in health and disease [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/106966
TESIS
Vassal, François. "Le Connectome du Langage dans le cerveau humain : étude structurelle et foncionnelle en tractographie par Imagerie tensorielle de diffusion, IRM fonctionnelle et stimulation électrique peropératoire." Thesis, Clermont-Ferrand 1, 2016. http://www.theses.fr/2016CLF1MM12.
Повний текст джерелаThe langage connectome is defined as the neuronal networks that subserve languagefunctions. Anatomically, it comprises specialized cortical areas and modulatory subcortical areas (i.e. deepgray nuclei and cerebellum), as well as their interconnections trough white matter (WM) fascicles.Although brain regions involved in language have been largely explored thanks to functional MRI (fMRI)and intraoprative electrical stimulation (IES), the underlying WM connectivity is still not mastered. It isnot only unknown which WM fascicles specifically contribute to language, but there is also much debateabout their precise anatomy and the functions they subserve during language processing. Betterunderstanding of the structural and functional organization of the language connectome is requisite toreduce postoperative morbidity in neurosurgery and develop targeted treatments for aphasiarehabilitation. Herein, our objective was to map structurally and functionally, in vivo, the subcorticalconnectivity of language. First, we conducted a preclinical study in 20 healthy subjects, combining DTItractography and fMRI (reading comprehension task) to yield connectivity associated with language. Weexplored 8 WM fascicles that have been proposed as putative candidates for language —i.e. arcuatefascicle, superior longitudinal fascicle, inferior fronto-occipital fascicle, uncinate fascicle, inferiorlongitudinal fascicle, middle longitudinal fascicle, operculopremotor fascicle, frontal aslant tract—, towhich we assigned functionality by tracking their connections to the fMRI-derived clusters. We generateda normative database of anatomical characteristics for each WM fascicle, such as volume, length, corticalterminations and their interhemispheric and interindividual variations. By using this construct, weprovided in explicit details the structural map of the language connectome. Second, this body ofknowledge was transposed to brain tumor surgery. Patients suffering of gliomas located close to languageregions were operated on under local anesthesia (i.e. awake surgery) in order to perform intraoperativelanguage mapping (object naming task). Essential language sites were localized through IES andanatomically characterized thanks to navigated tractography images. This intraoperative protocol allowedmaximum tumor resection while preserving language functions. Furthermore, it gave us a uniqueopportunity to perform reliable, real-time structure – function relationships, determining the role of 5WM fascicles (arcuate fascicle, inferior fronto-occipital fascicle, frontal aslant tract, orofacial premotorfibers, frontostriatal fascicle) in different subcomponents of language, i.e. phonological processing,semantic processing, articulatory planning, motor control and executive/cognitive control of verbalresponse. Globally considered, our results allow a better understanding of the anatomo-functionalorganization of the language network in the human brain. Beyond the scientific interest, the possibility toconstruct the individual (patient-specific) connectome paves the way for major applications inneurosurgery, in the perspective of personalized medicine. Today, the maximum safe resection of braintumors located in eloquent language areas, guided by navigated, multimodal images. Tomorrow, thedevelopment of new treatments for rehabilitation of post-stroke aphasia patients, such as the targeteddelivery of drugs, stem cells, or neuromodulation devices, fitting with the residual functional connectivityspared by the lesion
Petrovic, Aleksandar. "Connectivity driven registration of magnetic resonance images of the human brain." Thesis, University of Oxford, 2010. http://ora.ox.ac.uk/objects/uuid:fd95c6d4-06d2-41b4-b6f2-5cbd73cb83a9.
Повний текст джерелаPallarés, Picazo Vicente. "Individual traits versus invariances of cognitive functions: a model-based study of brain connectivity." Doctoral thesis, Universitat Pompeu Fabra, 2019. http://hdl.handle.net/10803/666806.
Повний текст джерелаÉs conegut en la literatura de neuroimatge que les xarxes cerebrals funcionals reflecteixen trets personals. Aquestes característiques individuals podrien interferir en caracteritzar la cognició entesa com la manera en què les xarxes es coordinen per realitzar una tasca, com mantenir l'atenció, recordar o processar informació visual. Cóm aquests aspectes individuals coexisteixen amb mecanismes generals, és, per tant, una pregunta clau en recerca sobre connectivitat cerebral. Aquest treball estudia la relació entre marcadors de connectivitat específics tant de subjectes, com de tasques. Se centra en dues escales temporals: la variabilitat entre sessions, i les fluctuacions ràpides produïdes durant una sessió d'adquisició. Utilitzem tècniques de machine learning per separar quantitativament les contribucions d'informació del subjecte i de l'estat cognitiu a la connectivitat. La metodologia presentada ens permet extreure aquelles xarxes representatives d'ambdues dimensions, així com aprofundir en la seva evolució, suggerint les escales temporals rellevants en la cognició.
There is consistent evidence in the neuroimaging literature that functional brain networks reflect personal traits. Individual specificity may interfere with the characterization of cognition, in terms of coordination of brain networks to perform a task, such as sustained attention, memory retrieval or visual information processing. How individual traits coexist with invariant mechanisms is, therefore, a key question in brain connectivity research. This work aims to examine the relationship between subject- and task-specific connectivity signatures. It focuses on two different timescales: day-to-day variability and faster fluctuations exhibited within a scanning session. We adopt a machine learning approach to quantitatively disentangle the contribution of subject information and cognitive state to the connectivity patterns. The proposed methodology allows us to extract the specific brain networks that support each of the two dimensions, as well as to delve into their changes over time, suggesting the relevant timescales for cognition.
Morra, Erica, and Lisa Zenker. "Chapter 1: In Search of Innate Leadership : Discovering, Evaluating and Understanding Innateness." Thesis, Linnéuniversitetet, Institutionen för organisation och entreprenörskap (OE), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-34622.
Повний текст джерелаFrança, Josefa jacinto de. "Construções apositivas: estruturas desgarradas introduzidas por ou seja e quer dizer." Universidade Federal da Paraíba, 2016. http://tede.biblioteca.ufpb.br:8080/handle/tede/8576.
Повний текст джерелаMade available in DSpace on 2016-08-25T11:12:19Z (GMT). No. of bitstreams: 1 arquivo total.pdf: 1437906 bytes, checksum: eda3008d89c5938770d382037e2f6809 (MD5) Previous issue date: 2016-02-22
This thesis analyzes often verbally functioning based expressions ou seja (that is) and quer dizer (that is to say) which introduce appositive constructions, present in op-eds in weekly periodicals belonging to Brazilian journalistic realm (VEJA, ISTOÉ, ÉPOCA) in 2012. Despite the fact that the labels attributed to such grammatical forms in current literature are varied, they are at first denominated conectores (connectors) in this thesis (GONÇALVES et al., 2007), as they connect the two units which compose the appositive construction – base and appositive units. They are later referred to as marcadores (markers) (MARTELOTTA; VOTRE; CEZÁRIO, 1996) as they sign reformulations carried out by text speaker/author. In order to carry out the research, interdisciplinary theoretical reference was Functional Linguistics, whose investigations are grounded in conceptual fundamentals of apposition and appositive constructions description in journalistic texts, allied to Textual Linguistics, which, through semantic relations study, helps to make a discursive connectors/markers’ profile. In this investigation, our main objective is to describe appositive constructions behavior spearheaded by the previously mentioned expressions, with reference to: a) generalizations about linguistic embodiment forms, marked by various punctuation marks, which permit their identification as desgarradas (dislocated) forms (DECAT, 2011); b) the different syntactic functions driven by the semantic relation of correferência do ponto de vista do locutor (co-reference from the speaker’s point of view) and performed by unit A base element (base or matrix); c) units weight relation (symmetry and asymmetry); d) expressions’ textual and discursive functions represented by unit B (appositive); and e) paraphrases types (WENZEL,1985) introduced by such connectors/markers. In order to achieve this purpose, we have taken as an object for analysis SN constructions (nominal syntagma) as well as the clause form (in the sentence) starting with a pragmatic and discursive approach. In corpus texts, the appositive constructions are used as argument and referencing strategy carriers. This is a descriptive and interpretative research, which leads to data qualitative and quantitative analysis, bearing in mind expressions’ syntactic, semantic and discursive profile. Final results confirm the hypothesis of discursive connectors/markers ou seja and quer dizer productivity in media written texts, introducing dislocated constructions which are highly functional in paraphrase’s contexts of use stablishing apposition.
En esta tesis se analiza el funcionamiento de las expresiones de base verbal, o sea, es decir, introductoras de las construcciones apositivas presentes en artículos de opinión en revistas semanales de ámbito periodístico (VEJA, ISTOÉ, ÉPOCA) de 2012. Aunque en la literatura actual, han sido cambiadas las rotulaciones asignadas a estas formas gramaticales, se les llama en esta tesis, al comienzo, conectores (GONÇALVES et al., 2007) para hacer la conexión entre las dos unidades que componen la construcción de aposición - unidad base y la unidad aposición; siendo después denominadas marcadores (MARTELOTTA; VOTRE; CEZÁRIO, 1996), por señalizar reformulaciones realizadas por el hablante/ autor del texto. Para la investigación, tomamos como base teórica, de carácter interdisciplinario, la Lingüística Funcional, que constituye la base de las investigaciones sobre los fundamentos conceptuales de la aposición y de la descripción de construcciones apositivas en estos textos, junto con Linguística Textual que, a través del estudio de las relaciones semánticas, ayuda en la caracterización de los conectores / marcadores del discurso. En este estudio, objetivamos describir esencialmente el comportamiento de las construcciones apositivas encabezadas por las expresiones citadas en relación con: a) las generalizaciones acerca de las formas de materialización lingüística, señaladas por varios signos de puntuación, que permiten identificarlas como desgarradas (DECAT, 2011); b) las diferentes funciones sintácticas, impulsadas por la relación semántica de correferencia bajo punto de vista del hablante y realizadas por el elemento base de la unidad (base o matriz); c) al cociente de peso (simetría y asimetría) de las unidades; d) las funciones textuales-discursivas representadas por la unidad B (aposición) de dichas construcciones; y e) los tipos de paráfrasis (WENZEL, 1985) introducidas por estos conectores / marcadores. Para lograr este propósito, tomemos como objeto de análisis construcciones en forma de SN (sintagma nominal) y también en la forma clausular (oracional), a partir de un enfoque que consideramos pragmático-discursivo. En los textos que conforman el corpus, las construcciones apositivas se utilizan como portadoras de las estrategias de argumentos y de remisión. La investigación es de carácter descriptivo e interpretativo, lo que llevó al análisis cuantitativo y cualitativo de los datos recogidos, teniendo en cuenta el perfil sintáctico, semántico y discursivo de esas construcciones. Los resultados finales confirman la hipótesis de la productividad de los conectores/marcadores del discurso, o sea, es decir, en textos escritos en los medios de comunicación, introductores de construcciones desgarradas, siendo altamente funcionales en los contextos de uso de las paráfrasis que forman la aposición.
Esta tese analisa o funcionamento das expressões de base verbal ou seja e quer dizer, introdutoras de construções apositivas, presentes em textos opinativos de periódicos semanais da esfera jornalística (VEJA, ISTOÉ, ÉPOCA) do ano de 2012. Apesar de, na literatura corrente, serem variadas as rotulações atribuídas a essas formas gramaticais, elas são denominadas nesta tese, a princípio, de conectores (GONÇALVES et al., 2007), por fazerem a conexão entre as duas unidades que compõem a construção apositiva – unidade base e unidade apositiva; sendo depois referidas como marcadores (MARTELOTTA; VOTRE; CEZÁRIO, 1996), por sinalizarem reformulações realizadas pelo autor do texto. Para a realização da pesquisa, tomamos como referencial teórico, de caráter interdisciplinar, a Linguística Funcional, que alicerça as investigações em torno dos fundamentos conceituais da aposição e da descrição de construções apositivas nesses textos, aliada à Linguística Textual, que, através do estudo das relações semânticas, auxilia na caracterização dos conectores/marcadores discursivos. Nesta investigação, objetivamos, essencialmente, descrever o comportamento das construções apositivas encabeçadas pelas expressões citadas no que concerne: a) a generalizações sobre as formas de materialização linguística, assinaladas por diversos sinais de pontuação, os quais permitem identificá-las como desgarradas (DECAT, 2011); b) às diferentes funções sintáticas, impulsionadas pela relação semântica de correferência do ponto de vista do locutor e desempenhadas pelo elemento base da unidade A (base ou matriz); c) à relação de peso (simetria e assimetria) das unidades; d) às funções textual-discursivas representadas pela unidade B (apositiva) das referidas construções; e e) aos tipos de paráfrases (WENZEL, 1985) introduzidas por esses conectores/marcadores. Para atingir esse propósito, tomamos como objeto de análise construções sob a forma de SN (sintagma nominal) e também sob a forma clausular (oracional), a partir de uma abordagem que consideramos pragmático-discursiva. Nos textos que constituem o corpus, as construções apositivas são usadas como portadoras de estratégias de argumentação e referenciação. A pesquisa tem caráter descritivo-interpretativo, o que levou à análise quanti-qualitativa dos dados colhidos, tendo em mente o perfil sintático, semântico e discursivo das referidas construções. Os resultados finais confirmam a hipótese da produtividade dos conectores/marcadores discursivos ou seja e quer dizer em textos escritos da mídia, introdutores de construções desgarradas, sendo estes altamente funcionais nos contextos de uso das paráfrases que dão forma à aposição.
Contreras, Joey Annette. "Using brain connectomics to detect functional connectivity differences in Alzheimer's disease." Diss., 2017. http://hdl.handle.net/1805/14603.
Повний текст джерелаProdromal Alzheimer’s disease (AD) has recently been identified as a disease state where pathophysiological changes may progress despite the absence of significant clinical symptoms. Yet, the specific processes of neural dysfunction occurring during this preclinical phase remain unclear. Resting state fMRI (RS-fMRI) in combination with brain connectomic measurements may be able to provide ways to measure subtle connectivity changes in different neurological disease states. For instance, RS-fMRI scans allow us to determine functionally connected yet spatially distinct brain regions that can then be separated into resting-state networks (RSNs). More recently, the exploration of RSNs in disease states have proved promising since they have been reliably altered when compared to a control population. By using brain connectomic approaches to assess functional connectivity we can evaluate the human connectome from a different and more global perspective to help us better understand and detect prodromal neurodegenerative disease states.
Yi-LunLi and 李沂倫. "Anatomical and functional connectivity analysis using Magnetic Resonance Imaging in Human Connectome Project." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/44204925397588896479.
Повний текст джерела國立成功大學
醫學資訊研究所
102
Recently, the relation among activated human brain regions has drawn interests and has been investigated. The imaging technique of functional magnetic resonance imagimg (fMRI) can be used to observe by changes in cerebral blood oxygenation and, therefore, brain connectivity. To understand how white matter (WM) tractography influences brain connectivity, we use diffusion magnetic resonance imagimg (dMRI) technique and algorithm to calculate WM map. The connectivity measurement combining fMRI and dMRI datasets is called anatomically weighted functional connectivity (awFC). Finally, the results show that, when using awFC datasets, the clusters have higher functional connectivity (FC) and structural connectivity (SC) strength when using awFC datasets.
Bharmauria, Vishal. "Investigating the encoding of visual stimuli by forming neural circuits in the cat primary visual cortex." Thèse, 2016. http://hdl.handle.net/1866/14129.
Повний текст джерелаBackground ‘Connectomics’— the mapping of neural connections, is a rapidly advancing field in neurosciences and it promises significant insights into the brain functioning. The formation of neuronal circuits in response to the sensory environment is an emergent property of the brain; however, the knowledge about the precise nature of these sub-networks is still limited. Even at the level of the visual cortex, which is the most studied area in the brain, how sensory inputs are processed between its neurons, is a question yet to be completely explored. Heuristically, this invites an investigation into the emergence of micro-circuits in response to a visual input — that is, how the intriguing interplay between a stimulus and a cell assembly is engineered and modulated? Methods Neuronal assemblies were recorded in response to randomly presented drifting sine-wave gratings in the layer II/III (area 17) of the primary visual cortex (V1) in anaesthetized cats using tungsten multi-electrodes. Cross-correlograms (CCGs) between simultaneously recorded neural activities were computed to reveal the functional links between neurons that were indicative of putative synaptic connections between them. Further, the peristimulus time histograms (PSTH) of neurons were compared to divulge the epochal synergistic collaboration in the revealed functional networks. Thereafter, perievent spectrograms were computed to observe the gamma oscillations in emergent microcircuits. Noise correlation (Rsc) was calculated for the connected and unconnected neurons within these microcircuits. Results The functionally linked neurons collaborate synergistically with augmented activity in a 50-ms window of opportunity compared with the functionally unconnected neurons suggesting that the connectivity between neurons leads to the added excitability between them. Further, the perievent spectrogram analysis revealed that the connected neurons had an augmented power of gamma activity compared with the unconnected neurons in the emergent 50-ms window of opportunity. The low-band (20-40 Hz) gamma activity was linked to the regular-spiking (RS) neurons, whereas the high-band (60-80 Hz) activity was related to the fast-spiking (FS) neurons. The functionally connected neurons systematically displayed higher Rsc compared with the unconnected neurons in emergent microcircuits. Finally, the CCG analysis revealed that there is an activation of a salient functional network in an assembly in relation to the presented orientation. Closely tuned neurons exhibited more connections than the distantly tuned neurons. Untuned assemblies did not display functional linkage. In short, a ‘signature’ functional network was formed between neurons comprising an assembly that was strictly related to the presented orientation. Conclusion Indeed, this study points to the fact that a cell-assembly is the fundamental functional unit of information processing in the brain, rather than the individual neurons. This dilutes the importance of a neuron working in isolation, that is, the classical firing rate paradigm that has been traditionally used to study the encoding of a stimulus. This study also helps to reconcile the debate on gamma oscillations in that they systematically originate between the connected neurons in assemblies. Though the size of the recorded assemblies in the current investigation was relatively small, nevertheless, this study shows the intriguing functional specificity of interacting neurons in an assembly in response to a visual input. One may form this study as a premise to computationally infer the functional connectomes on a larger scale.
(5929502), Sumra Bari. "ADVANCEMENTS IN NEUROIMAGING FOR MILD TRAUMATIC BRAIN INJURY AND MULTI-SITE RELIABILITY." Thesis, 2019.
Знайти повний текст джерелаHead injuries in collision sports have been linked to long-term neurological disorders. High school collision sport athletes, a population vulnerable to head injuries, are at a greater risk of chronic damage. Various studies have indicated significant deviations in brain function due to the accumulation of repetitive low-level subconcussive impacts to the head without externally observable cognitive symptoms. The aim of this study was to investigate metabolic changes in asymptomatic collision sport athletes across time within their competition season and as a function of mechanical force to their head. For this purpose, Proton Magnetic Resonance Spectroscopy (MRS) was used as a tool to detect altered brain metabolism in high school collision sport athletes (football and soccer) without diagnosed concussion. Also, sensors were attached to each athletes head to collect the count and magnitude of head impacts during their games and practices. Transient neurometabolic alterations along with prolonged recovery were observed in collision sport athletes.
Multi-site studies are becoming important to increase statistical power, enhance generalizability, and to improve the likelihood of pooling relevant subgroups together activities which are otherwise limited by the availability of patients or funds at a single site. Even with harmonized imaging sequences, site-dependent variability can mask the advantages of these multi-site studies. The aim of this study was to assess multi-site reproducibility in resting-state functional connectivity fingerprints, and to improve identifiability of obtained functional connectomes. We evaluated individual fingerprints in test- retest visit pairs within and across two sites and present a generalized framework based on principal component analysis (PCA) to improve identifiability. The optimally reconstructed functional connectomes using PCA showed a substantial improvement in individual fingerprinting of the subjects within and across the two sites and test-retest visit pairs relative to the original data. Results demonstrate that the data-driven method presented in the study can improve identifiability in resting-state functional connectomes in multi-site studies.
Moreau, Clara. "Mapping genome-wide neuropsychiatric mutation effects on functional brain connectivity : c opy number variants delineate dimensions contributing to autism and schizophrenia." Thesis, 2020. http://hdl.handle.net/1866/24592.
Повний текст джерелаResearch on Autism Spectrum Disorder (ASD) and schizophrenia (SZ) has mainly adopted a ‘top-down’ approach, starting from psychiatric diagnosis, and moving to intermediate brain phenotypes and underlying genetic factors. Recent cross-disorder studies have raised questions about diagnostic boundaries and pleiotropic mechanisms. By contrast, the recruitment of groups based on the presence of a genetic risk factor allows for the investigation of molecular pathways related to a particular risk for neuropsychiatric conditions (NPs). Copy number variants (CNVs, loss or gain of a DNA segment), which confer high risk for NPs are natural candidates to conduct such bottom-up approaches. Because CNVs have a similar range of adverse effects on NPs, we hypothesized that entire classes of CNVs may converge upon shared connectivity dimensions contributing to mental illness. Resting-state functional MRI (rs-fMRI) studies have provided critical insight into the architecture of brain networks involved in NPs, but so far only a few studies have investigated networks modulated by CNVs. We aimed at 1) Delineating the effects of neuropsychiatric variants on functional connectivity (FC), 2) Investigating whether the alterations associated with CNVs are also found among idiopathic psychiatric populations, 3) Testing whether deletions reorganize FC along general dimensions, irrespective of their localization in the genome. We gathered rsfMRI data on 502 carriers of eight NP-CNVs (high-risk), four CNVs without prior association to NPs as well as carriers of eight scarcer NP-CNVs. We also analyzed 756 subjects with idiopathic ASD, SZ, and attention deficit hyperactivity disorder (ADHD), and 5,377 controls. Connectome-wide analyses showed a positive gene dosage effect for the 22q11.2 and 1q21.1 CNVs, and a negative association for the 16p11.2 CNV. The effect size of CNVs on relative FC (mean-connectivity adjusted) was correlated with the known level of NP-risk conferred by CNVs. Consistent with results on cognition, we also reported that deletions had a larger effect size on FC than duplications. We identified similarities between high-risk CNV profiles and the connectivity architecture of individuals with NPs. The level of similarity was associated with mutation severity and was strongest in SZ, followed by ASD, and ADHD. The similarity was driven by the thalamus, and the posterior cingulate cortex, previously identified as hubs in transdiagnostic psychiatric studies. These results raised questions about shared mechanisms across CNVs. By comparing deletions at the 16p11.2 and 22q11.2 loci, we identified similarities at the connectivity, and at the gene expression level. We extended this work by pooling all deletions available for analysis. We asked if connectivity alterations were associated with the severity of deletions scored using pLI, a measure of intolerance to haploinsufficiency. The haploinsufficiency profile involved the thalamus, anterior cingulate cortex, and somatomotor network and was correlated with lower general intelligence and higher autism severity scores in 3 unselected and disease cohorts. An exploratory factor analysis confirmed the contribution of these regions to three latent components shared across CNVs and NPs. Our results open new avenues for understanding polygenicity in psychiatric conditions, and the pleiotropic effect of CNVs on cognition and on risk for neuropsychiatric disorders.