A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine. / Epilepsy is the most common neurologic condition seen in children. Focal cortical dysplasia (FCD), a seizure disorder characterized by abnormal cortical laminar development, comprises approximately 75% of medically intractable epilepsies in the pediatric population. A greater appreciation of the pathology and intrinsic properties of the epileptogenic zone may help in understanding why FCD lesions are drug‐resistant, and could potentially lead to more effective treatments in the pediatric population. Neuronal support cells such as microglia and astrocytes have shown to have a role in FCD pathology. These cells are also activated during aging and traumatic brain injury as evidence by morphological change. This study aims to characterize the spatial distribution of microglia and astrocytes using immunohistochemistry in dysplastic tissue of eight male pediatric patients diagnosed with FCD. Cortical specimens from patients who underwent surgical resection of focally dysplastic cortex at Phoenix Children’s Hospital between 2008 and 2014 were examined using immunohistochemistry. Primary antibodies against GFAP and Iba1, as well as structural staining using hematoxylin and eosin (H&E), were incubated on sections and further analyzed using bright‐field microscopy. A pattern of perivascular activated microglia was observed in five patients around at least one blood vessel, while a pattern of non‐localized ramified microglia was observed in the other three patients. No identifiable pattern of astrocytic distribution was found. Thus, distinct patterns of microglia, rather than astrocytes, suggest dual underlying mechanisms of epileptogenesis.

Este trabalho teve como objetivo estudar um caso específico de epilepsia refratária causada por uma má formação no tecido cerebral, denominada displasia cortical focal (DCF). Por ser uma má formação no cérebro, suas consequências aparecem desde a infância, em que ela, a DCF, é a principal causadora das epilepsias de caso refratário. O mapeamento da região com DCF geralmente é feito por meio de imagens de ressonância magnética em conjunto com outras técnicas, como, por exemplo, o PET (positron emission tomography), o EEG (eletroencefalograma) intracraniano, entre outras. Contudo, por serem técnicas muito caras, de difícil realização ou muito invasivas, e por sabermos que as regiões displásicas possuem uma rigidez diferente da do restante do cérebro, foi proposto nesta dissertação o estudo desses casos utilizando uma técnica barata, simples, não invasiva e sensível à rigidez tecidual, a elastografia por ultrassom, na qual, para causar a deformação do tecido cerebral, foram usadas próprias artérias internas do cérebro. Para tal estudo, criamos um algoritmo de processamento de dados com uma interface gráfica GUI (graphical user interface) capaz de mudar os parâmetros de processamento e ver seus resultados em tempo real. Em seguida, esse algoritmo foi estudado em um ambiente controlado em material mimetizador de tecido biológico (phantom), no qual construímos um bloco de 10 x 10 x 12cm3, preenchido com material que mimetiza as propriedades mecânicas e acústicas do tecido mole e inserimos nele uma bexiga canudo preenchida com um uido simulador de sangue e uma inclusão mais rígida do que a base do material, posicionada acima do canudo. Foi utilizado, também, um acionador mecânico pulsátil para simular a pulsação mecânica equivalente à pulsação sanguínea da artéria cerebral. Foram feitas imagens elastográcas e de velocidade utilizando somente a deformação causada pelo deslocamento da bexiga, no interior do phantom, e, através de uma transformada de Fourier, foi calculado o período de pulsação da bexiga. Vimos que as imagens elastográcas e de velocidade foram capazes de localizar a inclusão, e o processamento temporal pode nos mostrar com precisão a frequência de pulsação da bexiga canudo. Finalizada essa etapa laboratorial, zemos o mesmo procedimento, porém in vivo, para dois casos: um com DCF tipo III-B, no qual não enxergávamos nada no modo B; e outro com tipo II-B, no qual foi observado uma diferença de impedância mecânica pelo modo B. As imagens foram coletadas durante o procedimento cirúrgico pelo próprio cirurgião usando um transdutor microconvexo acoplado a uma plataforma de ultrassom, modelo Sonix RP, e processadas num segundo momento. Vimos, no primeiro caso, pelas imagens elastográcas, as regiões mais rígidas, supostamente displásicas, que não estavam aparecendo no modo B e, no segundo caso, uma região maior do que a apresentada no modo B. Nossos resultados das medidas de frequência da pulsação arterial, para ambas as situações, 61; 5BPM e 91BPM, caram bastante próximos do valor medido com o eletrocardiograma durante a coleta do sinal, 65BPM e 94BPM, respectivamente. Por meio dos resultados da análise histológica, pudemos conrmar que o que estávamos enxergando com nosso programa era realmente uma região displásica. Dessa forma, concluímos que nosso algoritmo funcionou bem para esses casos clínicos. / The mainly goal of this work was to study a specic case of refractory epilepsy generated by a malformation in the brain tissue, called focal cortical dysplasia (FCD). Due the fact it is a brain malformation its eects show up since the childhood where it is the principal epilepsy generator. The mapping of this region is usually made by magnetic resonance images with another technique, such as, for instance, the PET (position emition tomography), the EEG (electrocardiogram), and others. However, for the fact that these techniques are expensive, dicult to perform or invasive, and knowing that the dysplastic regions are stier than the regular brain tissue, it was proposed in this dissertation the use of ultrasound elastography as a cheaper, simpler and noninvasive image modality capable to detect dierences in the tissue stiness of the FCD region. To generate the strain in the brain tissue it was used the pulsation of the local arteries. To achieve our goal, we created a data processing algorithm in MATLAB with a graphic user interface (GUI) capable to change the processing parameters to see its results in real time. This algorithm was tested in phantom using a block of tissue mimicking material (10 x 10 x 12 cm3). A balloon of latex led with a blood mimicking uid was immersed in the middle of the phantom and a cylindrical inclusion of 1 cm of diameter was immersed above the balloon. The bulb of the balloon was keep outside of the phantom to be mechanically pressured by a dedicated magnetic actuator, simulating the mechanical pulsation of the brain arteries. The velocity and elastography images were studied using just the strain caused by the displacement of the wall of the balloon tube inside the phantom. The period of pulsation was precisely calculated from these images. After that, we did the same procedure in two in vivo cases: one with FCD type III-B; and the other with FCD type II-B. All our intraoperative images were acquired for the surgeons using a micro convex transducer linked to an Ultrasound platform (Sonix RP) and, then, processed o-line. In the B mode scanning we didnât see any formation inside the brain for the rst case, and for the second, we did. In the elastographic images we saw a clearly stiffer region in the rst case that was invisible in the B mode; and for the second case, we saw a bigger stiffer region than we saw in the B mode imaging too. And for both results, the arteria pulsation frequency, 61.5 BPM and 91 BPM, were veryclose to the measured value collected in the electrocardiogram during the surgery, 65 BPM and 94 BPM, respectively. Analyzing the histological results we could conrm that what we were showing in our elastographic images were FCD, indeed. Thereby we concluded that our algorithm had worked in these clinical data.

As displasias corticais focais constituem um grupo de malformações do desenvolvimento cortical cerebral. São consideradas a causa mais comum de epilepsia refratária na população pediátrica. A hemimegalencefalia faz parte deste grupo de malformação do desenvolvimento cortical e clinicamente devastadora em crianças, caracterizada pelo crescimento distorcido e anormal de um hemisfério cerebral. O mTOR (Mammalian Target of Rapamycin) é uma proteína quinase, que normalmente funciona como um regulador central de importantes funções fisiológicas, incluindo o crescimento e proliferação celular, metabolismo, autofagia, e sobrevivência e morte celular. O objetivo deste estudo foi identificar o defeito genético específico da hemimegalencefalia analisando os genes das vias de sinalização do mTOR. Foram selecionados 10 pacientes diagnosticados com hemimegalencefalia com faixa etária entre 0 á 18 anos de idade. Os pacientes submetidos ao procedimento cirúrgico foram designados para a coleta do material biológico (sangue e tecido encefálico) para análise genômica. Foram encontradas variantes somáticas de três genes relacionados a via mTOR com alto índice de patogenicidade, sendo elas; mutações missense na MTOR, HME 6584 (c.7255G> A, p.Glu2419Lys), HME 4146 (c.7498A> T, p.L7105f) mutações missense do gene PIK3CA, HME 4149 E542K (c.1624G> A), HME 4143 (c.1258T> C, p.C420R). A hipótese mediante esses resultados é que a mutação somática de genes que estão presentes na via mTOR podem ser uma das causas genéticas da HME. Essas observações sugeriram que a HME representa um espectro de distúrbios do neurodesenvolvimento resultando de distintas progenitoras que são determinados pelo tempo em que a mutação ocorreu durante o desenvolvimento cerebral. Pode-se esperar que uma mutação que ocorre precocemente durante o desenvolvimento afete um grande número de células e resulte em uma malformação maior, ao passo que a mesma mutação ocorrendo mais tarde no desenvolvimento poderia causar uma menor malformação. No futuro, numerosas mutações somáticas em genes conhecidos ou novos serão, sem dúvida, reveladas em amostras de cérebros ressecados e assim, possíveis correlações entre genótipos e fenótipos podem emergir, permitindo que o diagnóstico clínico genético ajude a prever o desfecho do paciente / Focal cortical dysplasias constitute a group of malformations of cerebral cortical development. They are considered the most common cause of refractory epilepsy in the pediatric population. Hemimegalencephaly is part of this group of malformation of cortical development and clinically devastating in children, characterized by the distorted and abnormal growth of a cerebral hemisphere. MTOR (Mammalian Target of Rapamycin) is a protein kinase, which normally functions as a central regulator of important physiological functions, including cell growth and proliferation, metabolism, autophagy, and cell death and survival. The aim of this study was to identify the specific genetic defect of hemimegalencephaly by analyzing the genes of the mTOR signaling pathways. Ten patients diagnosed with hemimegalencephaly with ages ranging from 0 to 18 years of age were selected. Patients submitted to the surgical procedure were assigned to the collection of biological material (blood and brain tissue) for genomic analysis. Somatic variants of three genes related to the mTOR pathway with high pathogenicity index were found; missense mutations in the MTOR, HME 6584 (c.7255G> A, p.Glu2419Lys), HME 4146 (c.7498A> T, p.Leu7105Phe) missense mutations of the PIK3CA gene, HME 4149 (c.1624G> A Glu542Lys), HME 4143 (c.1258 -> C, p.Cys420Arg). The hypothesis by these results is that the somatic mutation of genes that are present in the mTOR pathway may be one of the genetic causes of HME. These observations have suggested that HME represent a spectrum of neurodevelopmental disorders resulting from distinct progenitors that are determined by the time the mutation occurred during brain development. A mutation that occurs early in development may be expected to affect a large number of cells and result in a larger malformation, whereas the same mutation occurring later in development could cause a minor malformation. In the future, numerous somatic mutations in known or new genes will undoubtedly be revealed in samples of resected brains and thus, possible correlations between genotypes and phenotypes may emerge, allowing genetic clinical diagnosis to help predict the outcome of the patient

Este trabalho teve como objetivo estudar um caso específico de epilepsia refratária causada por uma má formação no tecido cerebral, denominada displasia cortical focal (DCF). Por ser uma má formação no cérebro, suas consequências aparecem desde a infância, em que ela, a DCF, é a principal causadora das epilepsias de caso refratário. O mapeamento da região com DCF geralmente é feito por meio de imagens de ressonância magnética em conjunto com outras técnicas, como, por exemplo, o PET (positron emission tomography), o EEG (eletroencefalograma) intracraniano, entre outras. Contudo, por serem técnicas muito caras, de difícil realização ou muito invasivas, e por sabermos que as regiões displásicas possuem uma rigidez diferente da do restante do cérebro, foi proposto nesta dissertação o estudo desses casos utilizando uma técnica barata, simples, não invasiva e sensível à rigidez tecidual, a elastografia por ultrassom, na qual, para causar a deformação do tecido cerebral, foram usadas próprias artérias internas do cérebro. Para tal estudo, criamos um algoritmo de processamento de dados com uma interface gráfica GUI (graphical user interface) capaz de mudar os parâmetros de processamento e ver seus resultados em tempo real. Em seguida, esse algoritmo foi estudado em um ambiente controlado em material mimetizador de tecido biológico (phantom), no qual construímos um bloco de 10 x 10 x 12cm3, preenchido com material que mimetiza as propriedades mecânicas e acústicas do tecido mole e inserimos nele uma bexiga canudo preenchida com um uido simulador de sangue e uma inclusão mais rígida do que a base do material, posicionada acima do canudo. Foi utilizado, também, um acionador mecânico pulsátil para simular a pulsação mecânica equivalente à pulsação sanguínea da artéria cerebral. Foram feitas imagens elastográcas e de velocidade utilizando somente a deformação causada pelo deslocamento da bexiga, no interior do phantom, e, através de uma transformada de Fourier, foi calculado o período de pulsação da bexiga. Vimos que as imagens elastográcas e de velocidade foram capazes de localizar a inclusão, e o processamento temporal pode nos mostrar com precisão a frequência de pulsação da bexiga canudo. Finalizada essa etapa laboratorial, zemos o mesmo procedimento, porém in vivo, para dois casos: um com DCF tipo III-B, no qual não enxergávamos nada no modo B; e outro com tipo II-B, no qual foi observado uma diferença de impedância mecânica pelo modo B. As imagens foram coletadas durante o procedimento cirúrgico pelo próprio cirurgião usando um transdutor microconvexo acoplado a uma plataforma de ultrassom, modelo Sonix RP, e processadas num segundo momento. Vimos, no primeiro caso, pelas imagens elastográcas, as regiões mais rígidas, supostamente displásicas, que não estavam aparecendo no modo B e, no segundo caso, uma região maior do que a apresentada no modo B. Nossos resultados das medidas de frequência da pulsação arterial, para ambas as situações, 61; 5BPM e 91BPM, caram bastante próximos do valor medido com o eletrocardiograma durante a coleta do sinal, 65BPM e 94BPM, respectivamente. Por meio dos resultados da análise histológica, pudemos conrmar que o que estávamos enxergando com nosso programa era realmente uma região displásica. Dessa forma, concluímos que nosso algoritmo funcionou bem para esses casos clínicos. / The mainly goal of this work was to study a specic case of refractory epilepsy generated by a malformation in the brain tissue, called focal cortical dysplasia (FCD). Due the fact it is a brain malformation its eects show up since the childhood where it is the principal epilepsy generator. The mapping of this region is usually made by magnetic resonance images with another technique, such as, for instance, the PET (position emition tomography), the EEG (electrocardiogram), and others. However, for the fact that these techniques are expensive, dicult to perform or invasive, and knowing that the dysplastic regions are stier than the regular brain tissue, it was proposed in this dissertation the use of ultrasound elastography as a cheaper, simpler and noninvasive image modality capable to detect dierences in the tissue stiness of the FCD region. To generate the strain in the brain tissue it was used the pulsation of the local arteries. To achieve our goal, we created a data processing algorithm in MATLAB with a graphic user interface (GUI) capable to change the processing parameters to see its results in real time. This algorithm was tested in phantom using a block of tissue mimicking material (10 x 10 x 12 cm3). A balloon of latex led with a blood mimicking uid was immersed in the middle of the phantom and a cylindrical inclusion of 1 cm of diameter was immersed above the balloon. The bulb of the balloon was keep outside of the phantom to be mechanically pressured by a dedicated magnetic actuator, simulating the mechanical pulsation of the brain arteries. The velocity and elastography images were studied using just the strain caused by the displacement of the wall of the balloon tube inside the phantom. The period of pulsation was precisely calculated from these images. After that, we did the same procedure in two in vivo cases: one with FCD type III-B; and the other with FCD type II-B. All our intraoperative images were acquired for the surgeons using a micro convex transducer linked to an Ultrasound platform (Sonix RP) and, then, processed o-line. In the B mode scanning we didnât see any formation inside the brain for the rst case, and for the second, we did. In the elastographic images we saw a clearly stiffer region in the rst case that was invisible in the B mode; and for the second case, we saw a bigger stiffer region than we saw in the B mode imaging too. And for both results, the arteria pulsation frequency, 61.5 BPM and 91 BPM, were veryclose to the measured value collected in the electrocardiogram during the surgery, 65 BPM and 94 BPM, respectively. Analyzing the histological results we could conrm that what we were showing in our elastographic images were FCD, indeed. Thereby we concluded that our algorithm had worked in these clinical data.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第18644号 / 医博第3943号 / 新制||医||1006(附属図書館) / 31558 / 京都大学大学院医学研究科医学専攻 / (主査)教授 河野 憲二, 教授 福山 秀直, 教授 渡邉 大 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

This study investigated memory in children with temporal lobe epilepsy and the ability to discern hippocampal dysfunction with conventional memory tests that are typically used to detect more global memory impairment. All data was obtained retrospectively from the epilepsy surgery program at a local children’s hospital. The research population consisted of 54 children with intractable epilepsy of temporal onset, balanced across pathology types (with and without hippocampal disease) and other demographics. Each was given a clinical battery prior to surgical intervention, which included the WRAML/WRAML2 Verbal Learning subtest from which the dependent variables for this study were extracted. The research hypothesis had predicted that memory retention between verbal learning and recall would be worse for participants with pathology that included hippocampal sclerosis than for those with non-hippocampal temporal lobe pathology. A two-way mixed-design ANOVA was used to test the hypothesis, which allowed incorporation of variables of interest related to memory factors, pathology type, and hemispheric laterality, as well as their various interactions. There was a significant main effect for change in the number of words retained from the final learning trial to the delayed recall. Although the interaction between memory retention and pathology type was not statistically significant, the average of the memory scores as it related to pathology by side did show significance. Thus, results did not support the hypothetical relationship between retention and hippocampal function. However, additional exploratory analyses revealed that the final learning trial by itself was associated with hippocampal pathology, which applied only to those participants with left-hemisphere lesions. Logistic regression with the final learning trial correctly classified 74 percent of participants into the appropriate pathology category, with 81 percent sensitivity to hippocampal dysfunction. Mean participant memory scores were nearly one standard deviation below the normative mean for both delayed recall and total learning scaled scores, regardless of pathology type or lesion hemisphericity. Thus, while the conventionally used indices of the WRAML Verbal Learning test are useful for determining overall memory status, they are not specific to pathological substrate. The within-subject main effect showed an expected loss of information across the time of the delay, but overall the recall score showed no association with hippocampal functioning. This study revealed the possibility of measuring hippocampal function at statistically significant group levels using learning scores from a widely used measure of verbal memory, even in participants with intact contralateral mesial temporal structures. It also indicated that hippocampal structures do not play a role during recall measures given after a standard time delay. Data further demonstrated a role of the hippocampus for encoding and transferring information beyond short term/working memory into long term. During the learning process, the hippocampus appears to work in concert with short-term memory systems, but does not take over the encoding process until enough repetitions have occurred to saturate the working memory buffer. This research represents a small, yet important step forward in our understanding of the hippocampus, with potentially important implications for the future study of memory constructs and mensuration.

<div><b>Rationale:</b> Focal cortical dysplasia (FCD) is a neurodevelopmental disorder that is associated with abnormal cortical development and is one of the most common drug-resistant epilepsies. The mechanistic target of rapamycin (mTOR) pathway is a highly complex pathway </div><div>associated with cell proliferation, synaptic plasticity, neuroinflammation, and cortical development. Hyperactivation of this pathway has also been implicated in hyperexcitability, seizures, and accumulation of beta-amyloid (Aβ) plaques and neurofibrillary tangles (NFT) through hyperphosphorylation of tau. Interestingly, Aβ and hyperphosphorylated tau have been reported in both rodent models and human patients of temporal lobe epilepsy (TLE) and FCD however, the mechanisms through which this occurs are still yet to be defined. Therefore, to identify the possible link between Aβ and tau pathology in FCD, we determined the spatial distribution and protein levels of Aβ and phosphorylated tau (p-tau) along with mTOR signaling </div><div>molecules. We hypothesized that there would be presence of Aβ and tau pathology as well as an increase in Aβ and p-tau protein levels that would be correlated with hyperactivation of the mTOR and GSK3 signaling pathways in tissue biopsies from human FCD patients compared to brain tissues from non-epileptic (NE) individuals.</div><div><br></div><div><b>Methods:</b> Cortical brain samples surgically resected from patients with FCD were used and compared to NE samples surgically resected from glioblastoma patients with no history of seizures or epilepsy. Immunostaining was used to determine the distribution of phosphorylation of S6 (p-S6), a marker for mTOR activation, and NeuN, a marker for neurons, along with Aβ and p-tau. Additionally, western blotting (WB) was used to determine the levels of mTOR signaling through p-S6 and GSK3 (p-GSK) along with Aβ and p-tau.</div><div><br></div><div><b>Results:</b> We found cortical dyslamination, mTOR activation, p-tau, and Aβ accumulation in cortices of patients with FCD with drug-resistant epilepsy. However, we did not find a </div><div>significant difference in the protein levels of p-S6 (p = 0.422), p-GSK3 (p = 0.947), p-tau (p = 0.649), and Aβ (p = 0.852) in cortical tissue homogenates derived from FCD patients when compared to those of NE samples. Additionally, we did not find sex differences in the protein </div><div>levels of p-S6 (p = 0.401), p-GSK3 (p = 0.331), p-tau (p = 0.935), and Aβ (p = 0.526). There was no significant correlation between age and p-S6 (p = 0.920), age and p-GSK3 (p = 0.089), age and p-tau (p = 0.956), and age and Aβ (p = 0.889). Moreover, there was no significant correlation between mTOR activation (p-S6), Aβ (p = 0.586) and p-tau (p = 0.059) nor GSK3 activation (p-GSK3), Aβ (p = 0.326), and p-tau (p = 0.715). Lastly, there was no significant correlation within the mTOR and GSK3 pathway activation within the same patients (p = 0.602).</div><div><br></div><div><b>Conclusion:</b> These data suggest that mTOR hyperactivation occurs alongside the presence of Aβ and tau pathology. However, several unknown factors such as medical and medication history may be altering the expression or suppression of these proteins. Additionally, there may be alternative pathways that crosstalk with mTOR signaling therefore influencing Aβ and tau pathology in FCD patients with drug-resistant epilepsy. Further investigation will need to be conducted to understand the detailed mechanisms through which Aβ and tau pathology occur in </div><div>FCD.</div>

No description available.

Mon travail de thèse porte sur les épilepsies focales avec ou sans malformations cérébrales de type dysplasie corticale focale. Il s'articule autour de (1) une étude fonctionnelle et génétique sur tissu cérébral postopératoire humain et (2) la caractérisation d'un nouveau modèle génétique chez l'animal. Tout d'abord, des mutations germinales hétérozygotes perte de fonction ont été identifiées dans DEPDC5, NPRL2 et NPRL3 qui codent pour le complexe GATOR1, un inhibiteur du complexe 1 de mTOR (mTORC1). Par la suite, des mutations somatiques cérébrales gain de fonction ont été identifiées dans MTOR. Nous avons émis l'hypothèse que ces mutations entrainent une hyperactivité de mTORC1, responsable des malformations cérébrales et de l'épilepsie des patients. J'ai observé une hyperactivité de mTORC1 dans les cellules cytomégaliques obtenues à partir de tissu cérébral post-opératoire de patients porteurs de mutations dans les gènes de GATOR1 ou MTOR. En parallèle, la caractérisation du premier modèle KO de Depdc5 a montré que les rats Depdc5+/- présentent des anomalies corticales rappelant celles des patients : délamination des couches corticales et cellules cytomégaliques avec une hyperactivité de mTORC1. Ce phénotype est prévenu par l'injection de rapamycine, un inhibiteur spécifique de mTORC1. Une susceptibilité accrue aux crises épileptiques induites par le pentylènetétrazole ainsi qu'un défaut des propriétés neuronales passives et actives ont été rapportés chez les rats Depdc5+/-. En conclusion, mes travaux de thèse ont contribué à mettre en évidence l'implication de la voie GATOR1-mTORC1 dans les épilepsies et dysplasies corticales focales. / In my PhD thesis work, I investigated focal epilepsies with and without brain malformations such as focal cortical dysplasia. I focused on two complementary aspects: (1) genetics and functional studies on human tissue samples and (2) characterization of a novel genetic animal model. First, germline heterozygous loss-of-function mutations were identified in DEPDC5, NPRL2 and NPRL3 genes that encode proteins which together form the GATOR1 complex, a repressor of the mTOR complex 1 (mTORC1). Additionally, brain somatic gain-of- function mutations were identified in MTOR gene that encodes mTOR itself. Both types of mutations are thought to lead to mTORC1 hyperactivity, and cause brain malformation and epilepsy in patients. To test this hypothesis, mTORC1 activity was monitored on post-operative brain tissue from patients carrying GATOR1 or mTOR genes mutations. Cytomegalic cells with mTORC1 hyperactivity were observed. Besides, the characterization of the first Depdc5 KO model revealed that Depdc5+/- rats present cortical structural abnormalities reminiscent of patient histopathology hallmarks: cortical layer dyslamination and cytomegalic cells with increased mTORC1 activity. This phenotype was prevented by rapamycin injection, a specific mTORC1 inhibitor. An increased susceptibility to pentylenetetrazol-induced epileptic seizures, as well as impaired passive and active neuronal properties were observed in Depdc5+/- rats compared to Depdc5+/+ rats. In conclusion, my PhD work largely contributed to emphasize the prominent role of the GATOR1-mTORC1 pathway in focal cortical dysplasia and epilepsies.

A displasia cortical focal (DCF) é uma das causas mais frequentes de epilepsia refratária. Na clínica, diferentes informações são usadas para localizar o foco epileptogênico, mas nenhum método é autossuficiente para evidenciar o local original das crises, associado com a presença da DCF. Embora haja relatos na literatura indicando alterações no padrão de distribuição de tons de cinza e morfologia dos voxels decorrentes da DCF, algumas limitações dos métodos desenvolvidos ainda impedem a utilização clínica. Nossa proposta foi investigar a capacidade de identificar DCF através de análises de espessura cortical e padrões de textura em imagens estruturais de Ressonância Magnética (RM), validando os métodos desenvolvidos a partir uma base de imagens retrospectiva, cujo tecido epileptogênico já havia sido ressecado e a DCF confirmada em análise histológica. A caracterização das DCF foi feita a partir da segmentação automática de tecido cortical saudável em conjunto com a segmentação manual da DCF feita por um especialista, e consiste na geração de mapas de característica e extração de valores de distribuições para comparação em análise estatística. Investigamos também a eficácia da detecção de DCF através do uso de algoritmos de aprendizado de máquina para classificação automática. Obtivemos precisão 0,81 e sensitividade 0,87, colocando o método desenvolvido em par com outros métodos presentes na literatura. Entretanto, foi identificada uma grande dependência do desempenho de métodos de pré-processamento, como corregistro e segmentação automática. / Focal Cortical Dysplasia (FCD) is one of the most frequent causes of refractory epilepsy. In clinical procedures, the information gathered from different techniques is used in order to locate the epileptogenic focus, associated with the presence of FCD. However, there is no self sufficient method to evidence the presence and location of such lesions and especially its extension. Although there are reports indicating change in gray scale intensity patterns and voxel morphology in the presence of DCF, limitations in developed methods still prevent their clinical use. Our proposal was to investigate the capability of identifying FCD through cortical thickness and texture patter analysis in structural MRI images, validating developed methods by utilizing a retrospective base of images from patients that were subjected to surgery, with the FCD being confirmed in histological analysis. Characterization of FCD was achieved from automatic segmentation of healthy cortex and manual segmentation of FCD tissue made by an specialist, and consists in the generation of texture or structural feature maps and comparison of distribution values in healthy or FCD tissue with statistical analysis. We also investigate the efficiency of FCD detection with Machine Learning automatic classification, obtaining precision of 0,81 and sensitivity of 0,87, placing our method on par with other methods in the literature. However, there is a major performance dependency of proposed method with pre-processing steps, like registration and automatic segmentation.