Les dernières avancées dans le domaine de l’imagerie par résonance magnétique permettent aujourd’hui de mieux comprendre l’anatomie et le fonctionnement du cerveau humain. L’IRM s’avère d’ailleurs aujourd’hui un outil clé pour la recherche de biomarqueurs d’imagerie dans la plupart des pathologies cérébrales. Nous nous sommes intéressés dans le cadre de cette thèse à l’étude de la connectivité anatomique des noyaux gris centraux, structures impliquées dans de nombreuses boucles cortico-sous-cortico-corticales, et dont l’atteinte est à l’origine de troubles moteurs à l’instar de la maladie de Huntington, du syndrome Gilles de la Tourette et de la maladie de Parkinson. Nous avons pour cela effectué plusieurs développements méthodologiques qui permettent de segmenter les noyaux gris centraux et d’inférer leur connectivité anatomique. Tout d’abord, nous avons développé une méthode de segmentation des noyaux gris centraux à partir de différents contrastes et capable de s’adapter à des cas pathologiques présentant une forte modification de ces structures. Ensuite, nous avons développé des méthodes robustes d’analyse et de sélection des fibres reliant les différentes structures cérébrales, obtenues à l’aide de méthodes de tractographie par IRM du processus de diffusion cérébrale. Ces nouvelles méthodes de sélection présentent l’avantage de tenir compte d’a priori anatomiques, et fournissent ainsi des résultats plus proches de la réalité que les résultats obtenus dans la littérature. Nous avons également développé une méthodologie permettant de construire des cartes de connectivité surfaciques afin de projeter les connexions des noyaux gris centraux sur la surface corticale et de comparer le profil de connectivité corticale des noyaux gris au sein d’une population et entre populations. Enfin, nous avons utilisé ces outils pour étudier les modifications putatives de la connectivité anatomique des noyaux gris centraux dans la maladie de Huntington et dans le syndrome Gilles de la Tourette. / The recent advances in magnetic resonance imaging helped understanding brain anatomy and function. Today, MR imaging is a key tool for inferring imaging-based biomarkers for most neuropathologies. In this work, we focused on the anatomical connectivity of the basal ganglia which are involved in several cortico-subcortical loops and which dysfunction is the origin of motor disorders like Huntington and Parkinson diseases and Gilles de la Tourette syndrome. We developed several tools allowing the segmentation of the basal ganglia and inferring their anatomical connectivity. First, we developed a method for deep nuclei segmentation using several contrasts and that was adapted for pathological cases presenting high modifications in the morphology of these structures. Second, we developed robust methods for the analysis and the selection of the fiber tracts linking different brain structures and obtained using dMRI and tractography methods. These novel tools have the advantage of taking into account anatomical prior knowledge. Therefore the obtained results are closer to the real anatomy than those obtained using the tools available in the literature. We also developed surface connectivity maps that project the cortical connections of the deep nuclei directly on the cortical surface and that allow the comparison of the connectivity profile of the deep nuclei between different subjects and different groups. Finally, we used these tools to study the putative modifications of the anatomical connectivity of the deep nuclei in the Huntington disease and Gilles de la Tourette syndrome.

Climate change is threatening biodiversity, causing populations and species to adapt, or otherwise, become extinct. Sea turtles have survived dramatic climate changes in the past, however, due to a history of intense human exploitation, and the current anthropogenic threats, their current resilience may be jeopardized. The main pursuits of this thesis were to i) evaluate the resistance of green turtles to predicted climate change impacts, using a globally significant rookery, in Poilão, Guinea-Bissau, as a case study; and ii) assess key population parameters to inform the conservation management of this resource. As the work developed I additionally had the opportunity to study the dynamics of an emerging disease in a juvenile foraging aggregation from Puerto Rico, which contributed to a broader understanding of resilience in this species. Specifically, I investigate the nest site selection behaviour of green turtles, their nesting environment, and the outcomes for their offspring, at Poilão, and apply this information to infer on the resilience of this population under future scenarios of climate change. I explore the connectivity established by the dispersal of post-hatchlings from Poilão, followed by their recruitment to foraging grounds, to set the geographical context of this major population. Lastly, I model the dynamics of Fibropapillomatosis, which affects juvenile green turtles globally, and examine the potential for disease recovery. The green turtle rookery in Poilão shows some resilience to expected climate change impacts. This significant population likely contributes to all juvenile foraging aggregations along the west coast of Africa, and to some extent to those in South America. Currently, green turtles are capable of recovery from Fibropapillomatosis, however, the incidence of disease may be enhanced by climate change.

A caracterização de redes e o estudo de sistemas, ambos utilizando grafos, é algo muito usado por várias áreas científicas. Uma das linhas deste estudo é denominada de grafos aleatórios, que por sua vez auxilia na criação de modelos para análise de redes reais. Consideramos um modelo de grafo aleatório não homogêneo criado por Kang, Pachón e Rodríguez (2016), cuja construção é feita a partir da realização do grafo binomial G(n; p). Para este modelo, estudamos argumentos e métodos usados para encontrar resultados sobre o limiar de conectividade, importante propriedade relacionada a existência assintótica de vértices e componentes isolados. Em seguida, constatamos algumas características positivas e negativas a respeito da utilização do grafo para modelar redes reais complexas, onde usamos de simulações computacionais e medidas topológicas. / The characterization of networks and the study of systems, both using graphs, is very used by several scientific areas. One of the lines of this study is called random graphs, which in turn assists in creating models for the analysis of real networks. We consider an inhomogeneous random graph model created by Kang, Pachón e Rodríguez (2016), where its construction is made from the realization of the binomial graph G(n; p). For this model, we studied the arguments and methods used to find results on the connectivity threshold, important property related to asymptotic existence of vertices and isolated components. Then we found some positive and negative characteristics about the use of the graph to model complex real networks, using computer simulations and topological measures.

One of the key requirements of fifth generation (5G) systems is having a connection to mobile networks without interruption at anytime and anywhere, which is also known as seamless connectivity. Nowadays, fourth generation (4G) systems, Long Term Evolution (LTE) and Long Term Evolution Advanced (LTE-A), are mature enough to provide connectivity to most terrestrial mobile users. However, for airborne mobile users, there is no connection that exists without interruption. According to the regulations, mobile connectivity for aircraft passengers can only be established when the altitude of the aircraft is above 3000 m. Along with demands to have mobile connectivity during a flight and the seamless connectivity requirement of 5G systems, there is a notable interest in providing in-flight wireless services during all phases of a flight. In this thesis, many issues related to the deployment and operation of the onboard systems have been investigated. A measurement and modelling procedure to investigate radio frequency (RF) propagation inside an aircraft is proposed in this thesis. Unlike in existing studies for in-cabin channel characterization, the proposed procedure takes into account the deployment of a multi-cell onboard system. The proposed model is verified through another set of measurements where reference signal received power (RSRP) levels inside the aircraft are measured. The results show that the proposed model closely matches the in-cabin RSRP measurements. Moreover, in order to enforce the distance between a user and an interfering resource, cell sectorization is employed in the multi-cell onboard system deployment. The proposed propagation model is used to find an optimum antenna orientation that minimizes the interference level among the neighbouring evolved nodeBs (eNBs). Once the optimum antenna deployment is obtained, comprehensive downlink performance evaluations of the multi-cell, multi-user onboard LTE-A system is carried out. Techniques that are proposed for LTE-A systems, namely enhanced inter-cell interference coordination (eICIC) and carrier aggregation (CA), are employed in the system analysis. Different numbers of eNBs, antenna mounting positions and scheduling policies are examined. A scheduling algorithm that provides a good tradeoff between fairness and system throughput is proposed. The results show that the downlink performance of the proposed onboard LTE-A system achieves not only 75% of the theoretical limits of the overall system throughput but also fair user data rate performance, irrespective of a passenger's seat location. In order to provide the seamless connectivity requirement of 5G systems, compatibility between the proposed onboard system deployment and the already deployed terrestrial networks is investigated. Simulation based analyses are carried out to investigate power leakage from the onboard systems while the aircraft is in the parked position on the apron. According to the regulations, the onboard system should not increase the noise level of the already deployed terrestrial system by 1 dB. Results show that the proposed onboard communication system can be operated while the aircraft is in the parked position on the apron without exceeding the 1 dB increase in the noise level of the already deployed terrestrial 4G network. Furthermore, handover parameters are obtained for different transmission power levels of both the terrestrial and onboard systems to make the transition from one system to another without interruption while a passenger boards or leaves the aircraft. Simulation and measurement based analyses show that when the RSRP level of the terrestrial system is below -65 dBm around the aircraft, a boarding passenger can be smoothly handed over to the onboard system and vice versa. Moreover, in order to trigger the handover process without interfering with the data transmission, a broadcast control channel (BCCH) power boosting feature is proposed for the in-cabin eNBs. Results show that employing the BCCH power boosting feature helps to trigger the handover process as soon as the passengers step on board the aircraft.

Une recrudescence de l’émergence ou de la réémergence de maladies infectieuses touchant l’homme ou ses animaux domestiques a été constatée ces dernières décennies. La majorité de ces maladies sont zoonotiques, c’est à dire originaires de la faune sauvage, et impliquent souvent un vecteur dans leur cycle de transmission. Parallèlement, des changements d’utilisation du sol en lien avec une intensification agricole modifient les paysages. L’objectif de cette thèse était d’améliorer l’état des connaissances de l’influence du paysage sur les relations entre hôtes, vecteurs et pathogènes. En Europe, les micromammifères peuvent abonder dans la plupart des écosystèmes terrestres, ce qui en fait des hôtes de choix pour les tiques généralistes Ixodes ricinus. Ils sont aussi des réservoirs d’agents infectieux transmis par les tiques. Les résultats de la thèse sont basés sur deux ans d’échantillonnage, printemps et automne, des micromammifères et des tiques dans différents paysages. Nous avons aussi recherché trois agents infectieux qu’ils hébergent et transmettent : Borrelia burgdorferi sensu lato (maladie de Lyme), Anaplasma phagocytophylum (anaplasmose) et Theileria (Babesia) microti (piroplasmose), ce dernier n’ayant pu être exploité en raison de sa trop faible prévalence. Les 24 sites d’échantillonnage étaient pour moitié en cœur ou en lisière de forêt et pour moitié dans des paysages agricoles offrant un gradient d’occupation du sol et d’ouverture du paysage. Le meilleur facteur explicatif de l’abondance de nymphes est la présence de larves d’I. ricinus l’année précédente. Les résultats indiquent aussi une relation entre le nombre de larves portées par les mulots sylvestres (Apodemus sylvaticus ; 76,5% des captures) et l’abondance de nymphes l’année suivante. Les campagnols roussâtres (Myodes glareolus ; 22,3% des captures) portaient moins de larves au printemps, certainement du fait d’une résistance acquise aux tiques des individus hivernants. Bien que ces deux espèces réagissent différemment aux variables de composition et de configuration du paysage, les abondances de nymphes n’étaient pas expliquées par ces variables. D’autres hôtes, comme les chevreuils (Capreolus capreolus), et des facteurs microclimatiques et météorologiques influencent donc probablement aussi les abondances et la distribution des tiques dans le paysage. La richesse spécifique des hôtes et l’abondance des campagnols roussâtres, trois fois plus infectés que les mulots sylvestres, amplifieraient les prévalences d’A. phagocytophylum de ces deux espèces de rongeurs. A l’inverse, la fragmentation du paysage, via la réduction de la taille des populations d’hôtes, semble agir négativement sur ces prévalences. Aucun patron spatial évident n’a été observé pour B. burgdorferi s.l.. De même, aucun lien n’a pu être fait entre les prévalences des rongeurs et celles des nymphes d’I. ricinus. Ces résultats suggèrent un rôle probable d’espèces de tiques plus spécialistes, I. trianguliceps et I. acuminatus, dans la circulation des agents infectieux étudiés, soulignant l’intérêt qu’il pourrait y avoir à considérer l’ensemble de la communauté de vecteurs dans de futures études. L’ensemble des résultats soulignent aussi l’importance qu’il y aurait à considérer un maximum d’hôtes micromammifères réservoirs, même peu abondants, à l’échelle du paysage pour mieux comprendre la transmission de ces maladies infectieuses vectorielles. / An increase in the emergence or in the reemergence of infectious diseases of human and his domestic animals has been observed in the last decades. Most of these diseases are zoonotic, i.e. originated from wildlife, and imply often a vector for their transmission. At the same time, land use changes linked to agricultural intensification have modified the landscapes. The aim of the thesis was to enhance the state of knowledge on the influence of the landscape on the relationships between hosts, vectors and pathogens. In Europe, small mammals can be abundant in most of terrestrial ecosystems; they are thus preferred hosts for the generalist tick species Ixodes ricinus. They are also reservoirs of tick-borne infectious agents. The results of this thesis are based on two years of sampling, in spring and autumn, of small mammals and ticks in different landscapes. We analyzed them for three of the infectious agents they host and transmit: Borrelia burgdorferi sensu lato (Lyme disease), Anaplasma phagocytophylum (anaplasmosis) and Theileria (Babesia) microti (piroplasmosis), this last one could not be exploited because of too low prevalence. The 24 sampling sites were half in the core or the edge of a forest and half in agricultural landscapes with a gradient of land cover and of landscape openness. The best explanatory variable for nymph abundance was the presence of I. ricinus larvae the previous year. The results also indicate a relationship between the number of larvae attached on wood mice (Apodemus sylvaticus ; 76,5% of the catches) and the abundance of nymphs the following year. Bank voles (Myodes glareolus ; 22,3% of the catches) harbored less larvae in spring, certainly because of an acquired resistance to ticks in the overwintering individuals. Despite that these two species react differently to the composition and configuration features of the landscape, the abundances of nymphs were not related to these features. Other hosts, like roe deer (Capreolus capreolus), meteorological and microclimatic factors probably influence the abundances and the distribution of ticks in the landscape. The host specific richness and the abundance of bank voles, which were threefold more infected than wood mice, likely amplified the prevalence of A. phagocytophylum of these two rodent species. Conversely, landscape fragmentation, via the reduction of host population sizes, seems to act negatively on this prevalence. No clear spatial pattern was observed for B. burgdorferi s.l.. Likewise, no link could be established between the prevalence of the rodents and the prevalence of the nymphs. These results suggest a possible role of more specialist tick species, I. trianguliceps and I. acuminatus, in the circulation of the studied infectious agents, emphasizing the possible interest of considering the whole vector community in further studies. The results also emphasize the importance of considering a maximum of small mammal reservoir hosts, even at low abundances, at the landscape scale to better understand the transmission of these vector-borne infectious diseases.

Neste trabalho foi realizado um estudo de aspectos relacionados ao uso de uma Rede de Sensores sem Fio, como uma tecnologia de apoio para o monitoramento ambiental em vinhedos. Com o intuito de estender o tempo de duração das baterias dos nos sensores dessa rede, procurou-se evitar coletas desnecessárias de dados. O programa aplicativo dos nos foi redefinido para possibilitar a escolha de um intervalo de amostragem próximo das necessidades, sendo essa escolha feita pelos próprios nos, a partir de condições predefinidas no aplicativo. A área de aplicação escolhida foi a viticultura, devido a grande influencia das condições ambientais no desenvolvimento fisiológico das videiras, influenciando no rendimento e na qualidade das uvas produzidas, justificando a adoção de um sistema de monitoramento. Uma das características dessas redes que motiva a sua aplicação na área agrícola e a possibilidade de coleta de dados com a resolução espaço-temporal adequada, permitindo aplicar eficientemente os conceitos da Agricultura de Precisão. Realizaram-se experimentos em um parreiral cultivado sob cobertura plástica, localizado em Bento Gonçalves, RS. Os aspectos da rede estudados compreenderam: o alcance de conectividade e qualidade do enlace entre os nos e a estação base; o desempenho da rede com os nos posicionados em diferentes alturas; a exatidão dos dados coletados, em comparação com um equipamento de maior precisão; e a avaliação da variabilidade microclimática dentro do parreiral. A validação da proposta envolveu a implementação de um protótipo funcional, testado em laboratório. O modelo proposto permitiu estimar o tempo de vida dos nos, considerando-se parâmetros como o tipo de bateria, o intervalo de amostragem e o tamanho do pacote de dados enviados pelos nos. Os resultados obtidos evidenciaram a existência de variabilidade microclimática tanto em diferentes alturas da videira, como espacialmente, dentro do parreiral. A interferência dos vegetais devido a água que contém foi avaliada a partir de dois parâmetros: o indicador de intensidade de sinal recebido e de qualidade de enlace, que indicaram maior interferência na altura do dossel das videiras. A correlação entre esses parâmetros levou a constatação que o melhor desempenho e o maior alcance de conectividade ocorrem com os nos posicionados na altura do cacho das videiras se comparados com as medições realizadas no dossel. A amostragem variável permitiu uma economia no numero de pacotes enviados, com menor consumo de energia, o que foi comprovado com o modelo proposto para tal finalidade. / A study of issues related to using a Wireless Sensor Network was carried out, as an enabling technology for environmental monitoring in vineyards. In order to extend the duration of sensor nodes batteries of the network, collecting unnecessary data was avoided. The nodes application program was redefined to allow the choice of a sampling interval close to the needs, and the choice made by the nodes themselves, based on predefined conditions in their application. The application area chosen was the viticulture because of the large influence of environmental conditions on the physiological development of the vines, influencing the yield and quality of produced grapes, justifying the adoption of a monitoring system. One of the characteristics of such networks that motivates its application in agriculture is the possibility of collecting data with the appropriate spatial and temporal resolution, allowing to efficiently apply the concepts of Precision Agriculture. Experiments were conducted in a vineyard cultivated under plastic overhead cover, situated in Bento Gonçalves, RS. The network aspects studied involved: connectivity range and link quality between nodes and gateway; network performance with nodes positioned at different heights; collected data accuracy, compared with a higher precision equipment; and microclimatic variability evaluation within the vineyard. The proposal validation involved the implementation of a functional prototype, tested in the laboratory. The model allowed estimating the nodes lifetime, considering parameters such as battery type, sampling interval and data packet size sent by sensor nodes. Results showed the existence of microclimatic variability both at different heights of the vine, and spatially within the vineyard. Vegetables interference due to the water contained in them was evaluated from two parameters: Received Signal Strength Indicator and Link Quality Indicator, which indicated greater interference in the height of the vines canopy. The correlation between these parameters led to the conclusion that the best performance and increased connectivity range occur with nodes positioned at the height of the bunch of grapes as compared with measurements made in the canopy. The variable sampling allowed savings in the number of sent packets, with lower power consumption, which agrees with the proposed model for this purpose.

A biodiversidade dos rios brasileiros encontra-se sob severa ameaça, em razão da fragmentação e perda de hábitat que os barramentos representam. Até o presente, os aproveitamentos hidrelétricos têm seu licenciamento ambiental condicionado a análises de impacto locais, sem avaliação dos impactos cumulativos de múltiplas barragens em uma bacia hidrográfica, com relação à conservação da diversidade da ictiofauna. Estudos anteriores para subsídio de licenciamento de múltiplas barragens na bacia Taquari-Antas (RS) propuseram cenários alternativos de conservação (número e posição de barragens), quando ainda não havia métricas de conectividade dendrítica desenvolvidas. Entre os problemas identificados naqueles estudos figuram a quantificação dos efeitos cumulativos das barreiras sobre a conectividade da bacia, o estabelecimento de áreas prioritárias para conservação e a influência do número e da posição das barreiras na conservação da biodiversidade aquática em uma bacia. Avaliamos a aplicação de conectividade para mensuração de impactos cumulativos de fragmentação de bacias hidrográficas através de índices de conectividade dendrítica recentemente propostos. Propomos um método genérico e replicável para analisar quantitativamente os efeitos de sucessivos barramentos em relação à conectividade dos hábitats aquáticos em processos de migração e dispersão de peixes em bacias hidrográficas. Utilizamos simulações de cenários de múltiplos barramentos para a avaliação. Propomos também uma sistematização para a simulação de múltiplos barramentos. Além disso, hierarquizamos áreas para conservação por conectividade, aplicamos as novas métricas de conectividade a estudos anteriores e demonstramos casos de cenários de alta conectividade com outras implicações na conservação. Discutimos o amadurecimento do método para aplicação em licenciamento ambiental e planejamento de conservação, bem como limitações atuais e perspectivas para trabalhos futuros. / Biodiversity of Brazilian rivers is nowadays seriously threatened due to fragmentation and habitat loss that impoundments represent. Up to now, hydroelectric power plants have their environmental licensing processes conditioned to local impact analysis, with no evaluation of cumulative impacts of multiple dams in a watershed landscape on the conservation of the integrity of ichthyofauna. Former studies for supporting environmental licensing processes of multiple hydroelectric dams in the Taquaria-Antas basin (RS, Brasil) proposed alternative conservation scenarios (number and position of barriers), in a time when there were no dendritic connectivity metrics developed. Among the problems identified at that time, we point quantification of cumulative effects of multiple barriers on the drainage connectivity, detecting prioritary areas for conservation and detecting the influence of the number and position of the barriers in the catchment for best conservation of aquatic biodiversity. We evaluated the application of connectivity for quantifying the impacts of fragmentation in hydrographic basins through recently proposed indexes. We proposed a replicable and generic method for quantifying the effects of successive impoundments in relation to aquatic habitat connectivity in ecological processes of migration and dispersal of fishes in hydrographic basins. We used multiple barriers scenarios simulation in order to perform the assessments. We also propose a way of systematizing multiple barriers simulations. Moreover, we rank areas for conservation by connectivity, apply the new connectivity metrics on former studies and demonstrate cases of high connectivity scenarios with other implications on conservation. We discuss maturing the method for application on environmental licensing and conservation planning as well as current limitations and perspectives for future studies.

abstract: Neural interfacing applications have advanced in complexity, with needs for increasingly high degrees of freedom in prosthetic device control, sharper discrimination in sensory percepts in bidirectional interfaces, and more precise localization of functional connectivity in the brain. As such, there is a growing need for reliable neurophysiological recordings at a fine spatial scale matching that of cortical columnar processing. Penetrating microelectrodes provide localization sufficient to isolate action potential (AP) waveforms, but often suffer from recorded signal deterioration linked to foreign body response. Micro-Electrocorticography (μECoG) surface electrodes elicit lower foreign body response and show greater chronic stability of recorded signals, though they typically lack the signal localization necessary to isolate individual APs. This dissertation validates the recording capacity of a novel, flexible, large area μECoG array with bilayer routing in a feline implant, and explores the ability of conventional μECoG arrays to detect features of neuronal activity in a very high frequency band associated with AP waveforms. Recordings from both layers of the flexible μECoG array showed frequency features typical of cortical local field potentials (LFP) and were shown to be stable in amplitude over time. Recordings from both layers also showed consistent, frequency-dependent modulation after induction of general anesthesia, with large increases in beta and gamma band and decreases in theta band observed over three experiments. Recordings from conventional μECoG arrays over human cortex showed robust modulation in a high frequency (250-2000 Hz) band upon production of spoken words. Modulation in this band was used to predict spoken words with over 90% accuracy. Basal Ganglia neuronal AP firing was also shown to significantly correlate with various cortical μECoG recordings in this frequency band. Results indicate that μECoG surface electrodes may detect high frequency neuronal activity potentially associated with AP firing, a source of information previously unutilized by these devices. / Dissertation/Thesis / Doctoral Dissertation Biomedical Engineering 2018

L'objectif de cette thèse était de mieux comprendre les mécanismes mnésiques liés à une stimulation nociceptive. Un premier axe de notre travail a été d'étudier l'influence de la douleur sur la mémorisation de mots grâce à une étude comportementale. Contrairement à d'autres émotions, nous avons montré qu'une douleur n'influençait pas la mémorisation du contenu d'un texte, qu'il soit lié à la douleur ou pas. Le deuxième axe, correspondant à la thématique majeure de la thèse, a été abordé à travers trois études : une étude comportementale permettant de tester la robustesse de la mémorisation nociceptive et ses spécificités; des enregistrements électro-encéphalographiques (EEG) intra-cérébraux afin d'identifier les régions cérébrales impliquées dans la mémorisation nociceptive et leurs interactions et enfin une exploration EEG de scalp chez des sujets sains permettant une vision plus globale des mécanismes mnésiques de ces stimulations. Ces études ont montré des phénomènes liés à la mémorisation non spécifiques à la stimulation nociceptive, telle que l'augmentation de la puissance alpha pendant la phase de rétention. Elles ont également mis en relief des spécificités liées à la mémorisation nociceptive en révélant l'existence d'un biais mnésique suite à une stimulation nociceptive de forte intensité, faussant l'évaluation d'une autre stimulation survenant ultérieurement. Les enregistrements EEG ont montré une augmentation de la connectivité beta entre des régions corticales de la matrice douleur et du cortex préfrontal lors de la phase de rétention. Cette connectivité pourrait refléter une trace de la mise en mémoire des informations nociceptives / The aim of this thesis was to better understand memory mechanisms of a nociceptive stimulation.A first axis of our work was to study pain influence on memorisation of words by a behavioural study. Contrary to other emotions, we demonstrated that pain didn’t influence the memory content of a text, related or not to pain.Our second axis, corresponding to the major thematic of this thesis, was addressed through three studies: a behavioural one allowing us to test robustness of nociceptive memorisation and it specificities; intracerebral electroencephalographic recordings (EEG) to identify brain regions involved in nociceptive memorisation and their interactions, and finally scalp EEG exploration in healthy subjects allowing a broader view of memorisation mechanisms of these stimulations.These studies demonstrated phenomena related to memorisation that was nonspecific to nociceptive stimulation, like alpha power enhancement during retention phase. They also highlight specificities related to nociceptive memorisation revealing memory bias existence following nociceptive stimulation of high intensity, distorting next stimulation evaluation. EEG recordings demonstrated beta connectivity enhancement between cortical regions of the pain matrix and prefrontal cortex during retention phase. This connectivity could reflect memory trace of nociceptive information

Sabe-se que diversas regiões do cérebro humano trabalham em sincronia, mesmo anatomicamente separadas, sugerindo conexões funcionais e estruturais. Dessa forma, nosso cérebro pode ser considerado uma rede que pode ser estudada para diferenças entre indivíduos e entre tarefas, em que os nodos podem ser diferentes regiões e as arestas podem ser medidas de conectividade funcional entre séries temporais de um sinal de ressonância magnética de cada região. Neste estudo, propomos analisar como conectividade funcional e parâmetros de rede cerebral se relacionam com desempenho intelectual e um estado de atenção sustentada. Foram adquiridas imagens de ressonância magnética de 30 indivíduos saudáveis jovens em estado de repouso e de atenção sustentada, a partir delas foram calculadas as conexões funcionais entre 90 regiões cerebrais usando o coeficiente de correlação entre pares de series temporais. Destes sujeitos foram estimados sete índices de inteligência a partir da aplicação do teste WAIS-III. As matrizes de conectividade evidenciariam um comportamento de rede complexa de mundo pequeno para limiares entre 0,2 e 0,5. Não foram encontradas associações entre parâmetros globais das redes ponderadas em estado de repouso e os índices de inteligência. Conectividade funcional e alguns parâmetros de rede locais evidenciaram correlações com pontuações de inteligência, principalmente nas regiões frontal, pré-central, parietal e occipital, giro fusiforme e supramarginal e caudado. Embora o p-valor não-corrigido seja bem pequeno e/ou haja simetria entre hemisférios em alguns resultados, ao ser considerado o efeito de múltiplas comparações para análise inteira não foram encontradas associações estatisticamente significativas, por isso as análises foram corrigidas para cada região (p-valor corrigido pelo FDR<0,05). Ainda assim, possivelmente um aumento do número de sujeitos levaria a resultados mais conclusivos. Não foram encontrados resultados que confirmassem a hipótese de que, para indivíduos normais, haveria uma maior anti-correlação de redes extrínsecas e intrínsecas como um todo para o estado de atenção focada em relação ao estado de repouso. Entretanto, durante o estado de atenção sustentada, foram encontradas algumas diferenças estatisticamente significantes nas conexões locais dentro das redes positivas e negativas à tarefa, evidenciadas por um aumento na magnitude das correlações positivas ou negativas durante a atenção sustentada, além de uma tendência de anti-correlação em conexões entre regiões positivas e negativas à tarefa. / It\'s known that some regions of the human brain work synchronously, even if they are anatomically separated, suggesting functional and structural connections. In this way, our brain can be considered a network that can be studied for individual or task differences and in which nodes can be the different regions and edges can be the measurements of functional connectivity between blood oxygen level-dependent signal time series from each region. In this study, we aim to analyze how functional connectivity and brain network parameters relate to intellectual performance and to sustained attention state. Resonance Magnetic images were acquired in 30 healthy young volunteers in resting and attentional state. The functional connections between 90 brain regions were computed from them using correlation coefficient between pairs of temporal series. Seven intelligence indices were estimated from these subjects through WAIS-III test application and associations between functional connectivity values or brain network parameters were sought. Connectivity matrices evidenced a small-world complex network behavior for thresholds between 0.2 and 0.5. No associations between global parameters using weighted networks were found. Functional connectivity and network parameters have evidenced some correlations with intelligence scores, mainly in frontal, pre-central, parietal, occipital regions, fusiform and supramarginal gyrus and caudate nucleus. Even that the uncorrected p-value was small and/or there was symmetry between hemispheres in several results, statistical significant associations were not found considering multiple comparisons correction for the entire analysis, therefore the analysis were corrected for each region (FDR corrected p-value <0.05). Even, increasing the number of subjects possibly would get more conclusive results. Results corroborant to the initial hypothesis of greater anti-correlation between default mode network and task-positive regions were not found for the sustained attention state. However, during sustained attention state, some statistically significant differences in local connections within task-positive and negative regions were found, evidenced by the increase of the strength of positive and negative correlations, besides of a trend of anti-correlation in connections between task-positive and negative regions.