Temporomandibular disorders (TMD) are a family of prevalent chronic pain disorders affecting masticatory muscles and/or the temporomandibular joint. There is no unequivocally recognized peripheral aetiology for idiopathic TMD. The central nervous system (CNS) may initiate and/or maintain the pain in idiopathic TMD due to sustained or long-term nociceptive input that induces maladaptive brain plasticity, and/or to inherent personality-related factors that may reduce the brain's capacity to modulate nociceptive activity. The main aim of this thesis is to determine whether there are structural neural abnormalities in patients with TMD, and whether these abnormalities are related to TMD pain characteristics, or to neuroticism. The specific aims are to delineate in TMD: (1) gray matter (GM) brain abnormalities and the contribution of pain and neuroticism to abnormalities; (2) the contribution of abnormal brain GM aging in focal cortical regions associated with nociceptive processes; and (3) abnormalities in brain white matter and trigeminal nerve and the contribution of pain. In groups of 17 female patients with TMD and 17 age- and sex- matched controls, magnetic resonance imaging revealed that patients with TMD had: (1) thicker cortex in the somatosensory, ventrolateral prefrontal and frontal polar cortices than controls, (2) cortical thickness in motor and cognitive areas that was negatively related to pain intensity, orbitofrontal cortical thickness that was negatively correlated to pain unpleasantness, and thalamic GM volume correlated to TMD duration, (3) an abnormal relationship between neuroticism and orbitofrontal cortical thickness, (4) abnormal GM aging in nociceptive, modulatory and motor areas, (5) widespread abnormalities in white matter tracts in the brain related to sensory, motor and cognitive functions, (6) reduced trigeminal nerve integrity related to pain duration, and (7) abnormal connectivity in cognitive and modulatory brain regions. In sum, this thesis demonstrates for the first time abnormalities in both peripheral nerve and CNS in patients with TMD.

O cérebro humano é considerado uma rede complexa em termos estruturais e funcionais em diferentes escalas. A caracterização da arquitetura desta rede pode ser considerada uma importante ferramenta no auxílio ao estudo de diferentes doenças neurodegenerativas. No presente estudo propusemos um software desenvolvido em JAVA para investigar esta arquitetura com base na correlação estatística de características morfológicas entre diferentes regiões do córtex. Foram utilizados dados de espessura cortical obtidos a partir de imagens de ressonância magnética de 191 indivíduos saudáveis e 93 pacientes com epilepsia. Foi proposto um modelo não linear para considerar o efeito da idade na espessura cortical com identificação de duas etapas: amadurecimento e envelhecimento. Os pacientes, quando comparados aos controles, apresentaram uma redução significativa na espessura cortical fundamentalmente nas regiões para-central, pericalcarina e do pré-cuneo no hemisfério direito. Esta diminuição também se manifestou ao longo da idade, com uma maior taxa de queda na região parahipocampal direita. Considerando a conectividade anatômica aqui calculada, o grupo de pacientes evidenciou alterações em 31\\% das possíveis conexões e de forma difusa. Adicionalmente, nas redes cerebrais dos pacientes houve uma diminuição de 15\\% no comprimento médio do caminho e no coeficiente de agrupamento. Aplicando-se um algoritmo de agrupamento, foram detectadas três comunidades para os indivíduos saudáveis e seis comunidades para os pacientes, confirmando uma quebra de organização estrutural neste ultimo grupo. Com este software esperamos trazer à comunidade mais uma ferramenta para análise das conexões cerebrais e suas modificações em determinadas patologias, contribuindo com seu entendimento e possível diagnóstico. / The human brain can be characterized as a complex network structurally and functionally in different levels. The description of the architecture of this network can be considered an important tool in understanding different neurodegenerative diseases. In the present study, we developed a software in JAVA to investigate this architecture based on statistical correlation of morphological characteristics between different cortex areas. It was used a database of cortical thickness obtained from magnetic resonance images of 191 healthy subjects and 93 patients with epilepsy. It was implemented a non-linear model to consider the effect of age in cortical thickness with identification of 2 stages: maturation and aging. The patients, when compared to healthy subjects, showed a significant reduction in cortical thickness, particularly at the areas precentral, pericalcarine and pré-cuneus of right hemisphere. This decrease also could be noted through the age, with a higher decrease rate at the right parahipocampal area. Considering the anatomical connectivity calculated, the patients group showed diffuse changes in 31\\% of the possible connections. Furthermore, in the patients brain network it was found a decrease of 15\\% in the characteristic path length and clustering coefficient. By applying a clustering algorithm, 3 clusters were detected in the healthy subjects and 6 clusters in the patients, confirming a breakdown of the structural organization in this last group. With our software we hope to bring to the community another tool to improve the brain connectivity analysis and its modifications in some pathologies, contributing with its understanding and possible diagnosis.

No description available.

Esquizofrenia (SZ) é uma doença multifacetada que afeta vários domínios, incluindo sintomas positivos e negativos. Devido a isso, até o momento, não existe um modelo animal adequado de SZ, o que contribui para o fato de sua fisiopatologia ainda ser pouco conhecida. Um dos melhores modelos animais de SZ desenvolvidos usa acetato metilazoximetanol (MAM), no 17º dia embrionário (MAM-E17) de ratas prenhes, o que leva a alguns dos padrões de histopatologia observados em SZ. O objetivo deste estudo é avaliar o uso do MAM-E17 para validar achados histológicos deste modelo animal de SZ. Um total de 4 controles e 13 MAM-E17 foram estudados. Os ratos submetidos ao tratamento MAM-E17 apresentaram uma diminuição no peso do cérebro e na área do hipocampo caudal esquerdo. Não houve diferença na área do hipocampo caudal direito nem no hipocampo dorsal. Os animais submetidos ao MAM-E17 mostraram uma diminuição na espessura do córtex pré-frontal direito. O modelo de roedor MAM-E17 demonstrou reproduzir os principais aspectos dos achados histológicos altamente relevantes na SZ. Assim, a administração do MAM-E17 pode ser um modelo animal apropriado para o estudo de aspectos histológicos de SZ. Isto é de suma importância para o melhor entendimento e tratamento desta devastadora doença no futuro. / Schizophrenia (SZ) is a multifaceted illness that affects multiple domains, including negative and positive symptons. Because of this, there is no appropriate animal model of SZ, which contributes to its still is poorly understood pathophysiology. One of the bestdeveloped animal models of SZ uses methylazoxymethanol acetate (MAM) in pregnant rat dams on embryonic day 17 (MAM-E17) to procedure patterns of histopathology similar to those observed in SZ. The aim of this study was to evaluate the use of MAM-E17 to validate the histological findings of this animal model of SZ. A total of 4 controls and 13 MAM-E17 were studied. Rats subjected to MAM-E17 treatment presented a decreased in brain weight and in the left caudal hippocampus area. There were no differences in the right caudal hippocampal area or in left and right dorsal hippocampal areas. The animals subjected to MAM-E17 showed a decrease in right prefrontal cortex thickness. The MAME17 rodent model reproduced key aspects of histological findings that are highly relevant in SZ. Thus, the admistration of MAM-E17 may be an appropriate animal model for the study of histological aspects of SZ. This is of paramount importance to the better understanding and treatment of this devastating disease in the future.

Esquizofrenia (SZ) é uma doença multifacetada que afeta vários domínios, incluindo sintomas positivos e negativos. Devido a isso, até o momento, não existe um modelo animal adequado de SZ, o que contribui para o fato de sua fisiopatologia ainda ser pouco conhecida. Um dos melhores modelos animais de SZ desenvolvidos usa acetato metilazoximetanol (MAM), no 17º dia embrionário (MAM-E17) de ratas prenhes, o que leva a alguns dos padrões de histopatologia observados em SZ. O objetivo deste estudo é avaliar o uso do MAM-E17 para validar achados histológicos deste modelo animal de SZ. Um total de 4 controles e 13 MAM-E17 foram estudados. Os ratos submetidos ao tratamento MAM-E17 apresentaram uma diminuição no peso do cérebro e na área do hipocampo caudal esquerdo. Não houve diferença na área do hipocampo caudal direito nem no hipocampo dorsal. Os animais submetidos ao MAM-E17 mostraram uma diminuição na espessura do córtex pré-frontal direito. O modelo de roedor MAM-E17 demonstrou reproduzir os principais aspectos dos achados histológicos altamente relevantes na SZ. Assim, a administração do MAM-E17 pode ser um modelo animal apropriado para o estudo de aspectos histológicos de SZ. Isto é de suma importância para o melhor entendimento e tratamento desta devastadora doença no futuro. / Schizophrenia (SZ) is a multifaceted illness that affects multiple domains, including negative and positive symptons. Because of this, there is no appropriate animal model of SZ, which contributes to its still is poorly understood pathophysiology. One of the bestdeveloped animal models of SZ uses methylazoxymethanol acetate (MAM) in pregnant rat dams on embryonic day 17 (MAM-E17) to procedure patterns of histopathology similar to those observed in SZ. The aim of this study was to evaluate the use of MAM-E17 to validate the histological findings of this animal model of SZ. A total of 4 controls and 13 MAM-E17 were studied. Rats subjected to MAM-E17 treatment presented a decreased in brain weight and in the left caudal hippocampus area. There were no differences in the right caudal hippocampal area or in left and right dorsal hippocampal areas. The animals subjected to MAM-E17 showed a decrease in right prefrontal cortex thickness. The MAME17 rodent model reproduced key aspects of histological findings that are highly relevant in SZ. Thus, the admistration of MAM-E17 may be an appropriate animal model for the study of histological aspects of SZ. This is of paramount importance to the better understanding and treatment of this devastating disease in the future.

O cérebro humano é considerado uma rede complexa em termos estruturais e funcionais em diferentes escalas. A caracterização da arquitetura desta rede pode ser considerada uma importante ferramenta no auxílio ao estudo de diferentes doenças neurodegenerativas. No presente estudo propusemos um software desenvolvido em JAVA para investigar esta arquitetura com base na correlação estatística de características morfológicas entre diferentes regiões do córtex. Foram utilizados dados de espessura cortical obtidos a partir de imagens de ressonância magnética de 191 indivíduos saudáveis e 93 pacientes com epilepsia. Foi proposto um modelo não linear para considerar o efeito da idade na espessura cortical com identificação de duas etapas: amadurecimento e envelhecimento. Os pacientes, quando comparados aos controles, apresentaram uma redução significativa na espessura cortical fundamentalmente nas regiões para-central, pericalcarina e do pré-cuneo no hemisfério direito. Esta diminuição também se manifestou ao longo da idade, com uma maior taxa de queda na região parahipocampal direita. Considerando a conectividade anatômica aqui calculada, o grupo de pacientes evidenciou alterações em 31\\% das possíveis conexões e de forma difusa. Adicionalmente, nas redes cerebrais dos pacientes houve uma diminuição de 15\\% no comprimento médio do caminho e no coeficiente de agrupamento. Aplicando-se um algoritmo de agrupamento, foram detectadas três comunidades para os indivíduos saudáveis e seis comunidades para os pacientes, confirmando uma quebra de organização estrutural neste ultimo grupo. Com este software esperamos trazer à comunidade mais uma ferramenta para análise das conexões cerebrais e suas modificações em determinadas patologias, contribuindo com seu entendimento e possível diagnóstico. / The human brain can be characterized as a complex network structurally and functionally in different levels. The description of the architecture of this network can be considered an important tool in understanding different neurodegenerative diseases. In the present study, we developed a software in JAVA to investigate this architecture based on statistical correlation of morphological characteristics between different cortex areas. It was used a database of cortical thickness obtained from magnetic resonance images of 191 healthy subjects and 93 patients with epilepsy. It was implemented a non-linear model to consider the effect of age in cortical thickness with identification of 2 stages: maturation and aging. The patients, when compared to healthy subjects, showed a significant reduction in cortical thickness, particularly at the areas precentral, pericalcarine and pré-cuneus of right hemisphere. This decrease also could be noted through the age, with a higher decrease rate at the right parahipocampal area. Considering the anatomical connectivity calculated, the patients group showed diffuse changes in 31\\% of the possible connections. Furthermore, in the patients brain network it was found a decrease of 15\\% in the characteristic path length and clustering coefficient. By applying a clustering algorithm, 3 clusters were detected in the healthy subjects and 6 clusters in the patients, confirming a breakdown of the structural organization in this last group. With our software we hope to bring to the community another tool to improve the brain connectivity analysis and its modifications in some pathologies, contributing with its understanding and possible diagnosis.

Esquizofrenia (SZ) é uma doença multifacetada que afeta vários domínios, incluindo sintomas positivos e negativos. Devido a isso, até o momento, não existe um modelo animal adequado de SZ, o que contribui para o fato de sua fisiopatologia ainda ser pouco conhecida. Um dos melhores modelos animais de SZ desenvolvidos usa acetato metilazoximetanol (MAM), no 17º dia embrionário (MAM-E17) de ratas prenhes, o que leva a alguns dos padrões de histopatologia observados em SZ. O objetivo deste estudo é avaliar o uso do MAM-E17 para validar achados histológicos deste modelo animal de SZ. Um total de 4 controles e 13 MAM-E17 foram estudados. Os ratos submetidos ao tratamento MAM-E17 apresentaram uma diminuição no peso do cérebro e na área do hipocampo caudal esquerdo. Não houve diferença na área do hipocampo caudal direito nem no hipocampo dorsal. Os animais submetidos ao MAM-E17 mostraram uma diminuição na espessura do córtex pré-frontal direito. O modelo de roedor MAM-E17 demonstrou reproduzir os principais aspectos dos achados histológicos altamente relevantes na SZ. Assim, a administração do MAM-E17 pode ser um modelo animal apropriado para o estudo de aspectos histológicos de SZ. Isto é de suma importância para o melhor entendimento e tratamento desta devastadora doença no futuro. / Schizophrenia (SZ) is a multifaceted illness that affects multiple domains, including negative and positive symptons. Because of this, there is no appropriate animal model of SZ, which contributes to its still is poorly understood pathophysiology. One of the bestdeveloped animal models of SZ uses methylazoxymethanol acetate (MAM) in pregnant rat dams on embryonic day 17 (MAM-E17) to procedure patterns of histopathology similar to those observed in SZ. The aim of this study was to evaluate the use of MAM-E17 to validate the histological findings of this animal model of SZ. A total of 4 controls and 13 MAM-E17 were studied. Rats subjected to MAM-E17 treatment presented a decreased in brain weight and in the left caudal hippocampus area. There were no differences in the right caudal hippocampal area or in left and right dorsal hippocampal areas. The animals subjected to MAM-E17 showed a decrease in right prefrontal cortex thickness. The MAME17 rodent model reproduced key aspects of histological findings that are highly relevant in SZ. Thus, the admistration of MAM-E17 may be an appropriate animal model for the study of histological aspects of SZ. This is of paramount importance to the better understanding and treatment of this devastating disease in the future.

Orientadores: Marcondes Cavalcante França Junior, Gabriela Castellano / Texto em português e inglês / Dissertação (mestrado profissional) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-24T20:36:08Z (GMT). No. of bitstreams: 1 Rezende_ThiagoJunqueiraRibeirode_M.pdf: 1634329 bytes, checksum: 78c3b3cb6bd66174acfe01359a6cb758 (MD5) Previous issue date: 2014 / Resumo: A doença de Machado-Joseph (SCA3/MJD) é a ataxia espinocerebelar mais frequente no mundo, resultante de uma expansão de tripletos CAG no gene MJD1 localizado no cromossomo 14q. Clinicamente ela é caracterizada por danos nos gânglios da base, tronco e cerebelo. Atualmente existem poucos estudos baseados em imagens de ressonância magnética (MRI) que investigam danos no córtex cerebral em pacientes com SCA3/MJD. O objetivo deste estudo foi investigar danos no córtex cerebral na SCA3/MJD usando MRI e correlacionar as possíveis áreas afetadas com dados clínicos, genéticos e neuropsicológicos. Foram recrutados para este estudo 49 pacientes com teste molecular de SCA3/MJD e 49 controles sadios. Os pacientes foram avaliados com a escala de ataxia SARA. Imagens de MR ponderadas em T1 foram adquiridas para todos os voluntários e usadas para a extração das medidas de espessura cortical, realizadas com o software FreeSurfer. O tamanho da expansão CAG médio, SARA e idade de início foram 72,1±4,2, 14,7±7,2 e 37,5±12,5, respectivamente. Os pacientes apresentaram redução de espessura nos córtex precentral e paracentral bem como nos hipocampos e lobos temporal e occipital. Também encontramos redução volumétrica no cerebelo, tálamo, caudado, putamen, globo pálido, tronco e diencéfalo ventral. A gravidade da doença apresentou correlação negativa com a espessura do giro precentral esquerdo (r=-0,302, p=0,035) e com o volume do tronco (r=-0,414, p=0,003). A espessura do giro angular direito apresentou correlação com a duração da doença (r=0,587, p=0,001), mas não com a expansão do tripleto de CAG. O subteste de semelhança de WAIS III apresentou uma correlação com a espessura do sulco central esquerdo (r=0,752, p=0,004) e como o giro occipital superior direito (r=0,704, p=0,016). Estes resultados sugerem que pacientes com SCA3/MJD apresentam dano cortical e subcortical difuso. Os achados estruturais se correlacionaram com as manifestações clínicas da doença, o que apoia a hipótese que a piora nas funções motora e cognitiva e o dano cerebral estão relacionados na SCA3/MJD / Abstract: Machado-Joseph disease (SCA3/MJD) is the most frequent spinocerebellar ataxia worldwide caused by an abnormal expansion of a CAG triplet at the MDJ1 gene located on chromosome 14q. Clinically, it is characterized by brainstem, basal ganglia and cerebellar damage. There are few MRI-based studies that investigated cerebral cortex damage in SCA3/MJD. The objectives of this study are to investigate cerebral cortex damage in SCA3/MJD and to correlate affected areas with clinical, genetics and neuropsychological data. We included 49 patients with molecular confirmation of SCA3/MJD and 49 healthy controls. The scale for assessment and rating of ataxia (SARA) was employed to quantify disease severity. We also performed a comprehensive neuropsychological battery to assess cognitive deficits. Volumetric T1 magnetic resonance images of the brain were acquired for all volunteers and used to calculate cortical thickness measures, performed using the FreeSurfer package. Mean CAG expansion, SARA score and age-at-onset were 72.1±4.2, 14.7±7.2 and 37.5±12.5, respectively. Patients had atrophy at precentral and paracentral cortices as well as the hippocampi, temporal and occipital lobes. We also found volumetric reduction of the cerebellum, thalamus, caudate, putamen, pallidum, brainstem and ventral diencephalon. SARA scores inversely correlated with left precentral gyrus thickness (r=-0.302, p=0.035) and brainstem volume (r=-0.414, p=0.003). Right angular gyrus thickness correlated with disease duration (r=0.587, p=0.001), but not (CAG) expansion. Similarity subscore of WAIS III presented a correlation with thickness of Left central sulcus (r=0.752, p=0.004) and Right superior occipital gyrus (r=0.704, p=0.016). Therefore, patients with MJD/SCA3 have widespread cortical and subcortical atrophy. These structural findings correlate with clinical manifestations of the disease, which support the concept that cognitive/motor impairment and cerebral damage are related in MJD/SCA3 / Mestrado / Fisiopatologia Médica / Mestre em Ciências

Les travaux réalisés dans cette thèse se situent à l'interface des domaines de l'acquisition en imagerie par résonance magnétique (IRM) et du traitement d'image pour l'analyse automatique des structures cérébrales. La mesure de modifications structurelles telles que l'atrophie corticale nécessite l'application d'algorithmes de traitement d'image. Ceux-ci doivent compenser les artefacts en IRM tels que l'inhomogénéité du signal ou les effets de volume partiel (VP) pour permettre la segmentation des tissus cérébraux puis l'estimation d'épaisseur corticale. Nous proposons une nouvelle modélisation de VP proche de la physique de l'acquisition baptisée modèle bi-exponentiel qui vient concurrencer le traditionnel modèle linéaire. Il nécessite l'utilisation de deux images de contrastes différents parfaitement recalées. Ce modèle a été validé sur des simulations et des fantômes physique et numérique dans un premier temps. Parallèlement, la récente séquence MP2RAGE permet d'acquérir deux images co-recalées par acquisition et leur combinaison aboutit à l'obtention d'une image insensible aux inhomogénéités du signal et d'une carte de T1 des tissus imagés. Nous avons testé notre modèle sur des données in vivo MP2RAGE et avons montré que l'application du modèle linéaire de VP conduit à une sous-estimation systématique de la substance grise à l'échelle du voxel. Ces erreurs se propagent à l'estimation d'épaisseur corticale, biomarqueur très sensible aux effets de VP. Nos résultats plaident en faveur de l'hypothèse suivante : la modélisation de VP pour les images MP2RAGE doit être différente de celle employée pour des images obtenues avec des séquences plus classiques. Le modèle bi-exponentiel est une solution adaptée à cette séquence particulière. / The work developed in this thesis is within the scope of magnetic resonance imaging (MRI) acquisition and image processing for the automated analysis of brain structures. The measurement of structural modifications with time such as cortical atrophy requires the application of image processing algorithms. They must compensate for MRI artifacts such as intensity inhomogeneities or partial volume (PV) effects to allow for brain tissues segmentation then cortical thickness estimation. We suggest a new PV model relying on the physics of acquisition named bi-exponential model that differs from the commonly used linear model by modelling brain tissues and image acquisition. It requires the use of two differently contrasted and perfectly coregistered images. This model has been validated with simulations and physical and digital phantoms in a first place. In parallel, the recent MP2RAGE sequence provides two coregistered images and their combination results in a bias-field corrected image as well as a T1 map of the scanned tissues. We tested our model with in vivo MP2RAGE data and demonstrated that using the linear PV model leads to a systematic gray matter proportion underestimation in PV voxels. These errors result in cortical thickness underestimation. Our results favor the following assumption: PV modelling with MP2RAGE images must differ from the usual linear PV model applied for images obtained from more classic sequences. The bi-exponential model is an adapted solution to this particular sequence.

Cette thèse s’intéresse à la capacité du cerveau à s’adapter à un environnement changeant. Plus spécifiquement, elle s’intéresse à la plasticité cérébrale dans le système olfactif. Les sommeliers, experts dans le domaine de l’olfaction, ont constitué notre modèle. Une première étude nous a permis d’établir un protocole afin de tester la performance olfactive des sommeliers. Dans une deuxième étude, nous avons testé des étudiants en sommellerie au début de leur formation d’un an et demi qui mène à la profession de sommelier. Nous avons observé que ces futurs experts de l’olfaction présentaient déjà, au cours des deux premiers mois, des capacités olfactives supérieures. Dans une troisième étude, nous avons de nouveau testé les étudiants à la fin de leur formation, afin d’examiner les effets d’un entraînement olfactif à long terme sur la performance olfactive et sur le cerveau : en plus de mesurer les capacités olfactives avec le test des Sniffin’ Sticks, nous avons utilisé l’imagerie par résonance magnétique (IRM) pour évaluer l’évolution du cerveau au cours de la formation en sommellerie. Nos principales observations concernent des changements au niveau de la structure cérébrale. Premièrement, le volume du bulbe olfactif a augmenté au cours de la formation, ce qui est en accord avec la littérature disponible à propos de cette structure. Deuxièmement, nous avons observé un épaississement au niveau du cortex entorhinal mais aussi un amincissement au niveau d’autres régions du cortex. Mises en relation avec les résultats d’études antérieures, ces observations soutiennent le récent modèle de surproduction-élagage selon lequel les changements dus à la plasticité liée à l’entraînement ne sont pas linéaires mais font intervenir différents processus en plusieurs phases. Ce modèle constitue une avancée importante dans la compréhension des mécanismes impliqués dans la plasticité cérébrale et devrait être pris en compte dans les futures études sur la plasticité. Bien que les résultats sur le plan neuroimagerie soient intéressants, les résultats de l’étude longitudinale relatifs à la performance olfactive n’étaient pas concluants sur le plan comportemental. Nous avons donc mis en place dans une quatrième étude une tâche d’identification d’odorants au sein de mélanges plus complexe et plus adaptée aux sommeliers qui a confirmé la supériorité de leurs capacités olfactives. Nous avons aussi entraîné des novices sur cette tâche pendant cinq jours pour tester les effets d’un court entraînement olfactif. Cette thèse est organisée sous forme de thèse par articles. Le premier chapitre correspond à l’introduction générale, qui est elle-même organisée en plusieurs grandes parties. Ces différentes parties définissent les concepts-clés de cette thèse : l’olfaction, les corrélations neuroanatomiques dans le système olfactif, la plasticité cérébrale, la plasticité liée à l’entraînement dans le système olfactif, la neuroimagerie. La dernière partie conclut l’introduction en présentant les objectifs et hypothèses de recherche. Les chapitres suivants correspondent aux articles rédigés au cours du doctorat et présentant les résultats des recherches. Le dernier chapitre constitue une discussion générale. Enfin, en annexes se trouvent deux articles publiés lors du doctorat, un chapitre à paraître dans un livre ainsi que des résultats non publiés. / This thesis is about the brain’s ability to adapt to an ever-changing environment. More specifically, it is about brain plasticity in the olfactory system. We used sommeliers, who are experts in olfaction, as our model. A first study allowed us to instate a protocol to assess sommeliers’ olfactory function. In a second study, we tested sommelier students at the start of their year-and-a-half-long training which is the prerequisite to become a professional sommelier. We observed that these future experts in olfaction already had, during the first two months of training, superior olfactory abilities. In a third study, we tested sommelier students again at the end of their training to examine the effects of a long-term olfactory training on olfactory performance and on the brain: beside assessing olfactory performance with the Sniffin’ Sticks test, we used magnetic resonance imaging (MRI) to examine the evolution of brain structure and function during sommelier training. Changes in brain structure constituted our main results. Firstly, olfactory bulb volume increased during sommelier training, which is in line with previous reports about this structure. Secondly, we observed a cortical thickness increase in the entorhinal cortex but also cortical thinning in other brain areas. Put together with findings from previous studies, these results support the recent overproduction-pruning model of plasticity according to which changes due to training-related brain plasticity are nonlinear but involve different processes and different phases. This model constitutes a great advance in the understanding of brain plasticity and its underlying mechanisms and should be considered in future studies about plasticity. Though neuroimaging results were interesting, results from olfactory tests in our longitudinal study were not conclusive so we conducted a fourth study to test the ability to identify odorants within mixtures, a task which is more complex and suitable for sommeliers than the Sniffin’ Sticks test. Sommeliers performed better. We also tested novices that we had trained on this task for five days to evaluate the effects of a short-term olfactory training. This thesis is organized by articles. The first chapter is a general introduction, itself organized in several parts. These different parts define the major concepts of this thesis: olfaction, neuroanatomical correlations in the olfactory system, brain plasticity, plasticity in the olfactory system, neuroimaging. The last part concludes the introduction with aims and hypotheses. The following chapters are articles written during PhD that present the results of our research. The last chapter is a general discussion of all the results. Finally, two articles published during PhD, a chapter that is to be published in a book and unpublished results are presented as appendices.