Si les régions cérébrales du langage ont étélargement explorées grâce à l’IRM fonctionnelle (IRMf) et la stimulation électrique directe (SED)peropératoire, leur connectivité reste encore incomplètement documentée. Il n’est pas seulement débattuquels faisceaux de SB contribuent au langage, mais également quelle est leur anatomie précise et leur rôlefonctionnel spécifique. Une meilleure compréhension du connectome du langage est requise pourdiminuer la morbidité postopératoire en neurochirurgie et développer de nouveaux traitements cibléspour la rééducation des aphasies. Notre objectif était de cartographier structurellement etfonctionnellement, in vivo, la connectivité du langage. Dans une première étude préclinique portant sur 2Oadultes sains, nous avons combiné des informations structurelles axonales révélées par la tractographieavec des informations fonctionnelles corticales dérivées de l’IRMf (tâche de lecture compréhensive). Huitfaisceaux de SB ont été explorés —i.e. faisceau arqué, faisceau longitudinal supérieur, faisceau frontooccipitalinférieur, faisceau unciné, faisceau longitudinal inférieur, faisceau longitudinal moyen, faisceauoperculo-prémoteur, faisceau frontal transverse—, dont le rôle fonctionnel a été analysé en recherchantune connexion entre leurs terminaisons corticales et les activations IRMf. Les caractéristiquesanatomiques des faisceaux (i.e. volume, longueur, terminaisons corticales), leurs asymétries interhémisphériqueset leurs variations interindividuelles ont été colligées. Ce protocole a permis deconstruire le connectome du langage et d’étudier en détails son organisation structurelle macroscopique.Dans une seconde partie, ces données ont été transposées à la clinique pour le traitement chirurgical depatients souffrant de tumeurs cérébrales (gliomes) en régions du langage. Pendant la résection tumorale,des images de tractographie intégrées à un système de neuronavigation ont été systématiquementcombinées à la SED au cours d’un test de dénomination orale d’images. Ce protocole opératoire a permisd’optimiser les résultats chirurgicaux en termes de qualité d’exérèse et de préservation du langage, et aconstitué une opportunité unique d’étudier en temps réel les corrélations structure – fonction. Encouplant la localisation anatomique précise où chaque SED a été délivrée —obtenue grâce aux images detractographie naviguées— et la sémiologie des paraphasies induites par la SED —colligée par unorthophoniste présent au bloc opératoire—, nous avons déterminé le rôle spécifique de 5 faisceaux tantcortico-corticaux (faisceau arqué, faisceau fronto-occipital inférieur, faisceau frontal transverse) quecortico-sous-corticaux (fibres prémotrices orofaciales, faisceau fronto-striatal) dans différentes souscomposantesdu langage, i.e. traitement phonologique, traitement sémantique, contrôle moteur,planification articulatoire, contrôle exécutif/cognitif de la réponse verbale. Considérés de façon globale,nos résultats permettent d’envisager une meilleure compréhension de l’organisation anatomofonctionnelledes réseaux cérébraux du langage. Au-delà de l’intérêt scientifique, la possibilité deconstruire le connectome du langage spécifique à chaque individu ouvre la voie vers d’importantesapplications en neurochirurgie, dans une perspective de médecine personnalisée. Aujourd’hui, la chirurgiedes tumeurs cérébrales guidée par l’image. Demain, le développement de nouveaux traitements pour larééducation des aphasies, e.g. la déposition ciblée d’agents pharmacologiques, de cellules souches ou deneuromodulations, interagissant directement avec la connectivité résiduelle épargnée par la lésion. / The 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.

Abstract in English below.

No description available.

A esquizofrenia é um transtorno mental de alta complexidade e até o presente momento nenhuma teoria conseguiu explicar completamente sua etiologia. Uma dessas teorias acredita que a transferência de informações entre os hemisférios de pacientes com esquizofrenia, que ocorre através do corpo caloso, comissura anterior e posterior, pode estar comprometida. Os objetivos do nosso estudo foram avaliar se existem alterações de conectividade inter-hemisférica (IH) e se essas alterações sofrem influência do gênero, em pacientes portadores de esquizofrenia quando comparados com seus parentes em primeiro grau e controles saudáveis, utilizando-se da imagem de ressonância magnética por tensor de difusão (IRMTD). Participaram do estudo 30 pacientes portadores de esquizofrenia, diagnosticados pelos critérios do Manual diagnóstico e estatístico das doenças mentais em sua quarta edição, os quais foram selecionados entre os pacientes do grupo de medicações atípicas do ambulatório de esquizofrenia e da enfermaria psiquiátrica do Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo; 30 parentes em primeiro grau desses pacientes; e 30 voluntários saudáveis. Todos os sujeitos do estudo foram submetidos a um exame de ressonância magnética, realizado no Centro de Ciências das Imagens e Física Médica de nossa instituição, onde foram adquiridas as sequências volumétricas e difusionais utilizadas em nosso estudo. Em posse das imagens de ressonância magnética dos 90 sujeitos do estudo, realizamos o pós-processamento dessas imagens, utilizando o software BrainVoyager QX® versão 2.4, com o intuito de obtermos, por meio dos dados provenientes da IRMTD, os mapas de anisotropia fracional (AF) e difusibilidade média (DM). Com esses mapas em mãos, procedemos à análise estatística do estudo, denominada de análise de covariância voxel a voxel (VANCOVA), no cérebro todo. Nessa análise, utilizamos a idade como covariável e verificamos a influência do gênero nos resultados encontrados. Nossos resultados 6 evidenciaram que os pacientes portadores de esquizofrenia apresentaram valores de AF e DM alterados em estruturas homólogas ao corpo caloso e áreas frontais adjacentes. Assim, podemos afirmar que descobrimos perda de conectividade IH nesses mesmos pacientes. Por meio de nosso estudo, descobrimos também a influência do gênero nos valores de AF e DM encontrados e então, consequentemente, podemos dizer que a conectividade IH de pacientes portadores de esquizofrenia sofreu influência do sexo. A idade também mostrou influenciar a conectividade IH de nossos pacientes. Com o atual conceito de que alterações de AF e DM podem ser encaradas como indicativos de comprometimento da mielina, e sabendo que a mielina participa diretamente das reações neuroquímicas do sistema glutamatérgico cerebral, também podemos dizer que o sistema glutamatérgico que participa da conectividade IH desses pacientes encontrava-se comprometido. / Schizophrenia is a highly complex mental disorder and no theory to date was able to fully explain the etiology of this disorder. One of the existing theories advocates that interhemispheric communication, which occurs through the corpus callosum and the anterior and posterior commissures, might be impaired in schizophrenia. Our study was designed to investigate whether there are interhemispheric connectivity (IC) alterations in schizophrenia and whether these alterations are influenced by gender through the comparison of schizophrenia patients with their first-degree relatives and healthy controls using diffusion tensor imaging (DTI). We enrolled 30 schizophrenia patients diagnosed according to the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders and selected from the Group of Atypical Medications of the Schizophrenia Outpatient Clinic and the psychiatric ward of the Ribeirão Preto Medical School University Hospital, 30 first-degree relatives of these patients and 30 healthy volunteers. All subjects underwent magnetic resonance imaging (MRI) scans for the acquisition of volumetric and diffusion sequences. The images were post-processed using BrainVoyager QX® version 2.4 to create fractional anisotropy (FA) and mean diffusivity (MD) maps from DTI data. The resulting data were analyzed using voxel-to- voxel analysis of covariance (VANCOVA) for the whole brain. In this analysis, we used age as a co-variable and assessed the influence of gender. Our results showed that schizophrenia patients had altered FA and MD values in structures homologous to the corpus callosum and adjacent frontal areas, suggestive of IC loss in the patients. We also found that gender influenced FA and MD values and, therefore, that IC in schizophrenia patients is influenced by gender. Age was also found to influence IC in our patients. Based on the current conception that FA and MD alterations may indicate myelin impairment and knowing that myelin participates directly in neurochemical reactions of the glutamatergic system in the brain, we can infer that the glutamatergic system, which is implicated in IC, is affected in schizophrenia and is influenced by gender.

Cette thèse "Tractographie cardiaque optimale utilisant l'IRM du tenseur de diffusion" à pour but de proposer et d'étudier une nouvelle formulation globale de la tractographie cardiaque à partir d'images de tenseur de diffusion synthétisant les données pondérées en diffusion. Les raisons sous-jacentes ayant conduits à une nouvelle formulation sont multiples. Les méthodes existantes sont pour la plupart locales comme les algorithmes de « streamline » (ligne de champ) et sont sujettes à de nombreuses imperfections, en particulier, leur faible robustesse par rapport au bruit dans les données. Un autre problème de ce type d'approches basé sur la résolution d'équations différentielles est leur dépendances quant à l'initialisation, ce dont notre méthode s'est totalement affranchit. L'autre but de cette thèse est de déterminer un ou plusieurs critères numériques pour comparer et qualifier les objets fibres. En effet, même s'il semble facile de caractériser qualitativement les fibres de façon visuelle, la création de mesures pour caractériser les fibres soit dans l'absolue, soit en comparaison aux données ou à d'autres fibre relève d'une toute autre approche. / This thesis "Optimal cardiac tractography using DT-MRI" offers and studies a new formulation of cardiac tractography based on the use of diffusion tensor images that synthetize the information of the diffusion weighted images. The underlying reasons that led to a new formulation are manifold. Existing methods are mostly based on local data, such as the streamlining algorithms, and thus are subject to many imperfections, especially they are not robust to noise in the data. Another problem with this type of approach based on solving differential equations is their dependency on initialization, unlike the method under study. The other aim of this thesis is to determine one or more numerical criteria to compare and qualify fibers. Even though it seems easy to qualitatively characterize fibers based on the visualization, creating measures to characterize the fibers, either in absolute or in comparison to the data or other fibers, is actually challenging.

The preterm delivery (<37 weeks gestation) rates are generally 5-9% in Europe, 12-13% in the US, and each year about 13 millions preterm infants are born worldwide (MacDorman and Mathews, 2009; Slattery and Morrison, 2002). The early exposure to the extra-uterine environment increases the risks of perinatal brain injury, involving more often the white matter. The white matter injury is characterized by a potential subsequent occurrence of cognitive problems, of developmental delay and of major motor deficits (e.g. cerebral palsy). <p>The most widely used imaging technique for studying neonatal brain is cranial ultrasound that can be performed at bedside and detects major brain abnormalities (hemorrhage, infarctions, cysts, dilatation of the lateral ventricles). However, it has a poor sensitivity for non-cystic or diffuse white matter abnormalities (WMA), the most common form of white matter injury in preterm infants. In comparison to ultrasound, MR (magnetic resonance) imaging has been reported to be superior in detecting WMA and is considered as an essential modality for imaging the neonatal brain. The standard sequences (e.g. T1-, T2-weighted imaging) are routinely performed for assessing not only brain anatomy, but also for evaluating brain lesions. Nevertheless, ¡§conventional MR imaging¡¨ has been criticized because it is limited in qualitative assessment and it does not provide information on the extent of specific white matter pathways injuries. <p>Currently, diffusion tensor imaging (DTI) enables more detailed exploration of white matter microstructure. Furthermore, DTI is now the best in vivo technique capable of delineating white matter pathways and quantifying microstructural changes not visible on conventional MR imaging. Diffusion tensor tractography allows the reconstruction of the principal white matter fibers. Moreover, it also provides diffusion indices like fractional anisotropy (FA), mean diffusivity (MD), longitudinal diffusivity (£f//), transverse diffusivity (£f¢r) that help assess the changes in fiber tracts, even before myelination becomes histologically evident. <p>Structural MR imaging studies performed in neonates are scarce. A number of essential questions are still under debate, concerning the normal white matter structure, as well as premature brain injury. First, left language lateralization and right handedness are complex phenomena incompletely understood and the question rises whether structural lateralization already exist in healthy preterm neonates at term-equivalent age. Second, it is of interest to know whether gender-related structural differences exist in healthy preterm neonates. Finally, in the assessment of preterm brain injury, the relationship between WMA on conventional imaging and altered diffusion indices in fiber tracts is still unclear. Therefore, the aims of the thesis were to investigate the brain structure in a population of preterm neonates at term-equivalent age by DTI and probabilistic tractography.<p>The first part of this thesis (Study I and Study II) was devoted to the study of white matter structural characteristics in healthy preterm neonates. Previous studies have shown that structural asymmetries in language and motor related fibers are present in adults and in infants (Dubois et al. 2009; Westerhausen et al. 2007). Our hypothesis was that these structural asymmetries are already present in preterm neonates at term-equivalent age. In Study I, DTI and probabilistic tractography were performed and we found volume and microstructural asymmetries in the language related parieto-temporal superior longitudinal fasciculi (SLF), in the motor related corticospinal tract (CST) and in the motor part of the superior thalamic radiation (STR) as well. In Study II, we found that compared to boys, girls have larger relative tract volumes and an advanced maturation in language and motor related fiber tracts. <p>The second part of this thesis (Study III) investigated whether WMA on conventional MR imaging are related to abnormalities within the fiber tract microstructures. WMA were classified as normal, mild, moderate and severe according to Woodward¡¦s classification (Woodward et al. 2006). Woodward and colleagues studied a large population (167 infants) of preterm infants at term equivalent age with MRI. They demonstrated that WMA were important predictors of neurological outcomes by comparing their results with the neurological outcomes of those infants at corrected age of two. We found that compared to neonates with no abnormalities, infants with mild abnormalities have significantly higher ƒÜ¢r in the right CST, the left anterior thalamic radiation (ATR), the left sensory STR and bilateral motor STR. Those findings might be related to injuries of premyelinating oligodendrocytes resulting in subsequent failure of both development and ensheathment of axons. Considering that those fiber tracts connect important cortical zones, microstructural changes in those fiber tracts might be responsible for the later neurodevelopment deficits in motor and cognitive functions. <p>We concluded that structural asymmetries and gender differences in motor and language related fibers are present in healthy preterm neonates at term-equivalent age well before the development of speech and hand preference. Structural asymmetries and gender differences have to be considered in neonatal white matter assessment. Finally, altered DTI indices are associated with WMA on conventional MR imaging in preterm neonates. Our results suggest that disrupted premyelination is the major correlate with WMA rather than axonal pathology. Non-invasive DTI and tractography constitute an additional tool for the assessment of white matter injuries, as it could provide more adequate diagnostic information on brain microstructure in preterm neonates at term-equivalent age. / Doctorat en Sciences médicales / info:eu-repo/semantics/nonPublished

L'imagerie en tenseur de diffusion (DTI) est basée sur la mesure de la mobilité des molécules d'eau permettant l'analyse de la microarchitecture du tissu cérébral. Le trajet des fibres blanches peut être alors reconstruit par des méthodes de tractographie déterministes basées sur la direction principale de la diffusion. Toutefois elle repose sur des outils mathématiques complexes donnant un regard indirect sur les structures anatomiques, et sa validation est un enjeu majeur. Notre objectif a été de concevoir un objet-Test (OT) tri-Dimensionnel permettant la validation de la diffusion dans des faisceaux de fibres imitant l'organisation cérébrale. Cet OT se compose de trois modules: BOITE, SOLUTION, FIBRE réalisés en impression 3D. Il se compose de solutions de glucose et de fibres de dyneema orientées dans les trois orientations de l’espace. Nous nous sommes intéressés au développement d'une méthode de contrôle qualité des mesures quantitatives de diffusion dans le module SOLUTION. / Diffusion Tensor Imaging (DTI) is based on the measurement of water diffusion mobility in order to investigate brain microarchitecture and white fiber connectivity. The trajectory of white fibers bundles can be reconstructed by deterministic tractography methods depending on the principal direction of diffusion in tissu. However, tractography consist to complex mathematical algorithms reflecting an indirect visualization of white fibers. Our goal consisted to design a 3D phantom which imitates brain's diffusion properties, offering different degrees of diffusion mobility and imitating the organization of brain fibers. The phantom consists of three components 3D-Printing: BOX, SOLUTION, FIBER. The phantom was composed of various glucose solutions and dyneema synthetical fibers organized in all 3 directions. We developed a quality control of quantitative measurements for the SOLUTION's component. We have lead a comparison of fibers reconstruction between tractography and ground truth in FIBER's component. Results show that : ADC values were ranged on those brain values with glucose solutions; FA,

La recherche de prédicteurs d’habilités langagières en aphasie post-accident vasculaire cérébral (AVC) basés sur la matière blanche a récemment vu un élan. Cela a été motivé par l’émergence du modèle à double-voie où des faisceaux de matière blanche dorsaux et ventraux jouent un rôle important dans le langage, ainsi que par l’avènement de la tractographie basée sur l’imagerie par résonance magnétique (IRM) de diffusion permettant l’étude in-vivo des faisceaux de matière blanche et de leurs propriétés structurelles. Les caractéristiques structurelles et la charge lésionnelle des faisceaux de matière blanche ont permis de prédire les troubles langagiers dans la phase chronique dans quelques études. Cependant, les prédicteurs aigus de matière blanche des habilités syntaxiques en aphasie post-AVC chronique sont méconnus. L’exploitation de la tractographie dans l’étude des faisceaux langagiers de matière blanche a été limitée par plusieurs défis méthodologiques, dont la difficulté de reconstruire des faisceaux ayant une architecture complexe. Des progrès méthodologiques ont été récemment introduits afin d’adresser ces limites, dont le plus important est la tractographie basée sur l’imagerie à haute résolution angulaire (« HARDI »). Cependant, la fiabilité test-retest de la reconstruction et des propriétés structurelles d’une approche de tractographie HARDI de pointe n’a pas encore été évaluée. Le premier article de cette thèse visait à évaluer la fiabilité test-retest de la reconstruction et des propriétés structurelles (anisotropie fractionnelle, FA; diffusivité moyenne, axiale et radiale, MD, AD, RD; nombre d’orientations de fibres, NuFO; volume du faisceau; longueur moyenne des « streamlines ») de faisceaux langagiers majeurs (arqué, inférieur fronto-occipital, inférieur longitudinal, unciné, AF, IFOF, ILF, UF) obtenus avec une approche de tractographie HARDI de pointe. La majorité des mesures de propriétés structurelles ont montré une bonne ou excellente fiabilité. Ces résultats ont des implications importantes pour l’utilisation d’une telle approche pour l’étude des faisceaux langagiers de matière blanche, car ils renforcent la confiance dans la stabilité des reconstructions et les propriétés structurelles obtenus avec la tractographie HARDI. Le second article de cette thèse visait à déterminer si et quelles propriétés structurelles (FA, AD, volume du faisceau), et la charge lésionnelle, de l’AF et l’UF gauches dans la phase aigüe (≤ 3 jours), obtenus avec l’approche de tractographie HARDI utilisée dans le premier article, prédisent les habilités syntaxiques dans le discours spontané en aphasie post-AVC chronique (≥ 6 mois). Des régressions multiples ascendantes ont révélé que le volume de l’AF prédit la production des verbes, la complexité des phrases et la complexité de la structure argumentale du verbe. Le volume de l’UF a amélioré la prédiction de cette dernière. Ces résultats indiquent que le volume semble être un bon prédicteur précoce des habilités syntaxiques dans le discours spontané en aphasie post-AVC chronique. Mis ensemble, les résultats de cette thèse soulignent l’utilité d’une approche de tractographie HARDI de pointe et son potentiel pour le développement futur de biomarqueurs précoces pouvant améliorer le pronostic de patients ayant une aphasie post-AVC chronique. Cela pourrait promouvoir l’optimisation des soins et le développement de thérapies pour le bienfait des patients et leurs familles. / The search for white matter predictors of language abilities in post-stroke aphasia has gained momentum in recent years. This growing interest has been driven by the emergence of the dual-stream framework where dorsal and ventral white matter bundles play an important functional role in language, as well as the advent of diffusion magnetic resonance imaging (MRI)-based tractography which allows the in-vivo investigation of white matter bundles and their structural properties. Structural characteristics, as well as the lesion load, of white matter bundles have been previously found to predict language impairments in the chronic phase. However, little is known about acute white matter predictors of syntactic abilities in chronic post-stroke aphasia. Leveraging tractography to study white matter language bundles has been limited by several methodological challenges, such as the difficulty of reconstructing white matter bundles with a complex fiber architecture. A number of methodological advances have been introduced fairly recently to address these limitations, the most important of which is the advent of tractography based on High Angular Resolution Imaging (HARDI). However, the test-retest reliability of the reconstruction and structural properties of a state-of-the-art HARDI-based tractography pipeline has not been previously assessed. The first article of the present thesis aimed to assess the test-retest reliability of the reconstruction and structural properties (fractional anisotropy, FA; mean, axial, radial diffusivity, MD, AD, RD; number of fiber orientations, NuFO; bundle volume; mean length of streamlines) of major white matter language bundles (arcuate, inferior fronto-occipital, inferior longitudinal, and uncinate fasciculi, AF, IFOF, ILF, UF) obtained using a state-of-the-art HARDI-based tractography pipeline. Most measures of structural properties showed good to excellent test-retest reliability. These findings have important implications for the use of such a pipeline for the study of white matter language bundles, as they increase our confidence that the reconstructions and structural properties obtained from the tractography pipeline are stable and not due to random variations in measurement. The second article of the thesis aimed to determine whether and which structural properties (FA, AD, bundle volume), as well as the lesion load, of the left AF and UF in the acute phase post-stroke (≤ 3 days), obtained with the same state-of-the-art HARDI-based tractography pipeline used in the first article, predict syntactic abilities in connected speech in chronic post-stroke aphasia (≥ 6 months). Forward multiple regressions revealed that the left AF’s volume predicted the percentage of verbs produced, the structural complexity of sentences, as well as verb-argument structure complexity. The left UF’s volume improved the prediction of verbs with a complex argument structure. These findings indicate that the bundle volume may be a good early predictor of syntactic ability in connected speech in chronic post-stroke aphasia. Overall, the findings of this thesis highlight the usefulness of a state-of-the-art HARDI-based tractography approach and its potential for the future development of early biomarkers that could improve the prognosis and personalized care of patients with chronic post-stroke aphasia. This would promote the optimization of patient care and the development of therapies for the benefit of patients and their families.

Bibliographical record: KURKOVÁ, Simona. Sonographic evaluation of sciatic nerve in individuals with radicular symptoms S1, Charles University, 2nd Faculty of Medicine, Department of Rehabilitation and Sports Medicine, 2019, p. 99, Thesis Supervisor: Mgr. Stanislav Machač Ph.D. Abstract The thesis deals with radicular symptomatics S1 and sonographic imaging and evaluation of sciatic nerve in individuals with unilateral radicular manifestation. The theoretical part describes anatomy and biomechanics of nerve structures, radicular syndrome and its clinical image, diagnostics and treatment. The theory also includes the less known extraspinal causes manifesting themselves as radicular syndrome, the effects of which may be equally important in differential diagnosis. It describes classical and new possibilities of nerve imaging with emphasis on sonography and approach of new procedures such as MRI tractography. In the practical part, the aim of the thesis is to evaluate morphological changes of sciatic nerve in patients with unilateral symptomatic S1 by sonographic imaging of the nerve during its course, from the subgluteal groove to the popliteal groove. It also examines the relationship between the pathophysiology and symptomatology of these patients, comparing whether changes in nerve size correlate with...

Der menschliche inferiore Parietallappen (IPC) gehört zum Assoziationskortex und spielt eine wichtige Rolle bei der Integration von somatosensorischen (taktilen), visuellen und akustischen Reizen. Bisher gibt es keine eindeutigen Informationen über den strukturellen Aufbau dieser Hirnregion. Parzellierungen anhand der Zytoarchitektur reichen von zwei (Brodmann 1909) bis sieben Subareale (Caspers et al. 2006). Homologien zwischen dem IPC des Menschen und Makaken-Affen sind weitestgehend unbekannt. In der vorliegenden Arbeit wurden der Aufbau und die Konnektivitäten des menschlichen IPC genauer untersucht. Dazu führte man eine konnektivitätsbasierte Parzellierung des IPC an 20 Probanden durch. Als Methode kam Diffusions-Tensor-Imaging (DTI) kombiniert mit probabilistischer Traktogra-phie zum Einsatz. Der IPC konnte anhand der Konnektivitäten in drei Subareale (IPCa, IPCm, IPCp) parzelliert werden. Diese besitzen in beiden Hemisphären eine ähnliche Größe und eine rostro-kaudale Anordnung. Die Parzellierung ist vergleichbar mit der des Makaken-IPC, bei dem ebenfalls eine Unterteilung in drei Areale (PF, PFG, PG) und eine rostro-kaudale Anordnung nachgewiesen werden konnte. Jedes Subareal des menschlichen IPC besitzt ein individuelles Konnektivitätsmuster. Beim Menschen als auch beim Makaken gibt es starke Verbindungen zum lateralen prämotorischen Kortex und zum superioren Parietallappen. Diese Gemeinsamkeiten lassen darauf schließen, dass strukturelle Eigenschaften im Laufe der Evolution erhalten geblieben sind. Allerdings sind beim Menschen auch Neuentwicklungen nachweisbar. Dazu gehören die deutlich hervortretenden Verbindungen zum Temporallappen. Möglicherweise haben sich diese erst während der Evolution entwickelt und sind beim Menschen als Teil des perisylvischen Sprachnetzwerkes an der Sprachbildung beteiligt.:1. Einleitung 1.1. Der inferiore Parietalkortex 1.2. Konnektivitätsbasierte-Parzellierung durch Diffusions-Tensor-Bildgebung 1.3. Motivation 1.4. Überblick 2. Methoden 2.1. Theoretische Grundlagen 2.1.1. Magnet-Resonanz-Bildgebung 2.1.2. Diffusionsgewichtete Magnet-Resonanz-Tomographie 2.1.3. Diffusions-Tensor-Bildgebung 2.1.4. Traktographie in der weißen Substanz 2.1.5. Parzellierungsmethoden 2.2. Datenerfassung 2.3. Datenverarbeitung 2.4. Parzellierung des IPC 2.4.1. Definition der Analyseregion 2.4.2. Bestimmung der Startvoxel 2.4.3. Probabilistische Traktographie 2.4.4. Clustering 2.4.5. Populationskarte 2.4.6. Statistische Auswertung der Parzellierungsergebnisse 2.5. Analyse der Konnektivitäten des IPC 2.5.1. Berechnung der Konnektivitäten 2.5.2. Statistische Auswertung der Konnektivitäten 3. Ergebnis 3.1. Definition der Analyseregion 3.2. Analyse der Parzellierung 3.3. Statistische Auswertung der Parzellierung 3.4. Zusammenfassung der Parzellierungsergebnisse 3.5. Populationskarte aller Probanden 3.6. Statistische Auswertung weiterer Eigenschaften 3.6.1. Schwerpunkte der Areale 3.6.2. Größe der Areale 3.7. Analyse der Konnektivitäten 3.8. Statistische Auswertung der Konnektivitäten 3.9. Vergleich der linken und rechten Hemisphäre 4. Diskussion 4.1. Zwei oder drei Regionen: Welche Parzellierung ist am geeignetsten für den IPC? 4.2. Welche Konnektivitäten charakterisieren den IPC? 4.3. Vergleich von Mensch und Makaken 4.3.1. Homologien in der Parzellierung des IPC 4.3.2. Homologien in den Konnektivitäten des IPC 4.4. Funktionelle Bedeutung der IPC Parzellierung 4.4.1. Der IPC des Makaken 4.4.2. Der IPC des Menschen 4.5. Anmerkung zu den Methoden 4.5.1. Definition der Analyseregion 4.5.2. Auflösung der Diffusions-Tensor-Bildgebung 4.5.3. Traktographie Artefakte 4.6. Zusammenfassung 5. Anhang 5.1. Glossar 5.2. Abkürzungsverzeichnis 5.3. Detaillierte Abbildung der Ergebnisse 6. Danksagung 7. Zusammenfassung der Arbeit 8. Literaturverzeichnis 9. Publikation 10. Eigenständigkeitserklärung 11. Lebenslauf / The human inferior parietal cortex convexity (IPCC) is an important association area, which integrates auditory, visual and somatosensory information. However, the structural organization of the IPCC is a controversial issue. For example, cytoarchitectonic parcellations reported in the literature range from two to seven areas. Moreover, anatomical descriptions of the human IPCC are often based on experiments in the macaque monkey. In this study we used diffusion-weighted magnetic resonance imaging (dMRI) combined with probabilistic tractography to quantify the connectivity of the human IPCC, and used this information to parcellate this cortex area. This provides a new structural map of the human IPCC, comprising three sub-areas (IPCa, IPCm, IPCp) of comparable size, in a rostro-caudal arrangement in the left and right hemisphere. Each sub-area is characterized by a connectivity fingerprint and the parcellation is similar to the subdivision reported for the macaque IPCC (rostro-caudal areas areas PF, PFG, and PG). However, the present study also reliably demonstrates new structural features in the connectivity pattern of the human IPCC, which are not known to exist in the macaque. This study quantifies inter-subject variability by providing a population representation of the sub-area arrangement, and demonstrates substantial lateralization of the connectivity patterns of IPCC.:1. Einleitung 1.1. Der inferiore Parietalkortex 1.2. Konnektivitätsbasierte-Parzellierung durch Diffusions-Tensor-Bildgebung 1.3. Motivation 1.4. Überblick 2. Methoden 2.1. Theoretische Grundlagen 2.1.1. Magnet-Resonanz-Bildgebung 2.1.2. Diffusionsgewichtete Magnet-Resonanz-Tomographie 2.1.3. Diffusions-Tensor-Bildgebung 2.1.4. Traktographie in der weißen Substanz 2.1.5. Parzellierungsmethoden 2.2. Datenerfassung 2.3. Datenverarbeitung 2.4. Parzellierung des IPC 2.4.1. Definition der Analyseregion 2.4.2. Bestimmung der Startvoxel 2.4.3. Probabilistische Traktographie 2.4.4. Clustering 2.4.5. Populationskarte 2.4.6. Statistische Auswertung der Parzellierungsergebnisse 2.5. Analyse der Konnektivitäten des IPC 2.5.1. Berechnung der Konnektivitäten 2.5.2. Statistische Auswertung der Konnektivitäten 3. Ergebnis 3.1. Definition der Analyseregion 3.2. Analyse der Parzellierung 3.3. Statistische Auswertung der Parzellierung 3.4. Zusammenfassung der Parzellierungsergebnisse 3.5. Populationskarte aller Probanden 3.6. Statistische Auswertung weiterer Eigenschaften 3.6.1. Schwerpunkte der Areale 3.6.2. Größe der Areale 3.7. Analyse der Konnektivitäten 3.8. Statistische Auswertung der Konnektivitäten 3.9. Vergleich der linken und rechten Hemisphäre 4. Diskussion 4.1. Zwei oder drei Regionen: Welche Parzellierung ist am geeignetsten für den IPC? 4.2. Welche Konnektivitäten charakterisieren den IPC? 4.3. Vergleich von Mensch und Makaken 4.3.1. Homologien in der Parzellierung des IPC 4.3.2. Homologien in den Konnektivitäten des IPC 4.4. Funktionelle Bedeutung der IPC Parzellierung 4.4.1. Der IPC des Makaken 4.4.2. Der IPC des Menschen 4.5. Anmerkung zu den Methoden 4.5.1. Definition der Analyseregion 4.5.2. Auflösung der Diffusions-Tensor-Bildgebung 4.5.3. Traktographie Artefakte 4.6. Zusammenfassung 5. Anhang 5.1. Glossar 5.2. Abkürzungsverzeichnis 5.3. Detaillierte Abbildung der Ergebnisse 6. Danksagung 7. Zusammenfassung der Arbeit 8. Literaturverzeichnis 9. Publikation 10. Eigenständigkeitserklärung 11. Lebenslauf