A avaliação neuropsicológica é instrumento auxiliar para lateralização em epilepsia temporal (ET). Desempenho comprometido em memória verbal (MV) e não verbal (MNV) sugeririam, respectivamente, disfunção no sistema de memória do hemisfério dominante e não dominante. Não há consenso sobre a capacidade lateralizatória da avaliação de memória em pacientes com epilepsia. Estudou-se o poder lateralizatório da avaliação neuropsicológica em testes de memória verbal e não verbal em ET secundária a esclerose mesial temporal (EMT) unilateral. Comparamos o desempenho em memória verbal (RAVLT e o Memória Lógica) e não verbal (RVDLT e a figura complexa de Rey) em 87 pacientes destros com EMT (44 direita, 43 esquerda) e 42 controles. Pacientes e controles tinham escolaridade>8 anos, QI>70, sem comorbidades. Pacientes com EMTE tiveram desempenho rebaixado comparado a controles e EMTD em evocação livre e tardia do RAVLT. EMTE e EMTD tiveram desempenho rebaixado em relação a controles em evocação livre e tardia em Memória Lógica. EMTD tiveram desempenho rebaixado em relação a controles em evocação tardia da figura complexa de Rey. Observou-se baixa prevalência de dificuldade em ambos tipos de memória em ambos os grupos. Quando considerado acometimento de específico de MV observou-se associação com EMTE, com baixa sensibilidade, médio valor preditivo positivo (VPP) e alta especificidade. Quando considerado acometimento específico de MNV observou-se associação com EMTD, com baixa sensibilidade e altos valor preditivo positivo (VPP) e especificidade. O poder lateralizatório da testagem neuropsicológica de memória em EMT é observado, em apenas uma parcela de pacientes com EMT unilateral / Neuropsychological testing is a standard tool in the evaluation of patients with epilepsy. It allows assessment of performance in various cognitive domains, and is used as a lateralizing tool for seizure focus localization. Poor performance in verbal memory (VM) test is believed to indicate a dominant hemisphere focus. Poor performance in nonverbal memory (NVM) tests would localize the focus to the nondominant hemisphere. There still is a paucity of evidence of the ability of neuropsychological testing to predict seizure focus lateralization. We studied the lateralizing ability of neuropsychological testing of VM and NVM in a sample of 87 right handed patients with epilepsy secondary to unilateral mesial sclerosis (MTS) (44 right R, 43 left - L) and 42 controls (C), with an IQ>70, eight or more years of schooling, without comorbidities. LMTS patients performed significantly worse than controls in free and delayed recall of RAVLT items. L and RMTS performed worse than controls in immediate and delayed recall of the Logical Memory stories. RMTS performed worse than controls in delayed recall of the Complex Rey Figure. Our findings showed a low prevalence of VM and NVM impairment in both groups, an association between specific VM deficit and LMTS, with fair PPV and good specificity, and low sensibility. Selective NVM impairment was associated with RMTS, with good PPV and specificity for RMTS, and low sensibility. The lateralizing power of neuropsychological testing is noted only in a minority of patients with specific selective patterns of VM and NVM impairment

Pacientes com epilepsia do lobo temporal farmacorresistente, frequentemente, possuem esclerose hipocampal como lesão epileptogênica. Muitas vezes, estes pacientes se beneficiam de lobectomia temporal para redução da ocorrência de crises epilépticas. Para que possam se submeter a este procedimento, é necessário o uso da videoeletroencefalografia prolongada para delimitação apurada da zona epileptogênica. Apesar dos avanços dos métodos diagnósticos nesta área, a busca por um instrumento que permita uma avaliação clara da chance de uma vida livre de crises após cirurgia permanece. No presente trabalho, a apresentação do padrão eletroencefalográfico ictal foi estudado, de forma a se pesquisar se existe relação entre a sua ocorrência e permanência em apenas um hemisfério cerebral com um melhor prognóstico pós-cirúrgico. Foram revisados os dados eletroencefalográficos ictais e os prontuários médicos de 284 pacientes. Procedeu-se à classificação de seus padrões eletroencefalográficos ictais em unilaterais ou bilaterais, e seu prognóstico após um, dois e cinco anos após cirurgia em livre de crise ou não livre de crise epiléptica. Apresentavam padrão unilateral 132 pacientes, e 152 apresentavam padrão bilateral. Estavam livres de crises 236 pacientes, e 48 ainda persistiam com crises epilépticas após cirurgia. Não houve associação entre padrões ictais unilaterais e uma vida livre de crises epilépticas após a cirurgia (diferença de 7,5%; p=0,092; chi-quadrado). Dessa forma, não se pode aplicar o padrão ictal eletroencefalográfico como ferramenta para predição de uma vida livre de crises após lobectomia temporal em pacientes com epilepsia da região mesial do lobo temporal associada à esclerose hipocampal. / Patients with drug-resistant temporal lobe epilepsy usually have hippocampal sclerosis as an epileptogenic lesion. Most of the times, these patients are benefited from temporal lobectomy for seizure relief. For this procedure to occur, a long-term videoelectroencephalogram is necessary for the accurate delineation of the epileptogenic zone. Despite the developments in the diagnostic methods on this area, the quest continues for an instrument that allows a clear evaluation of the chance to obtain a seizure-free life after epilepsy surgery. In the present study, the electroencephalographic ictal patterns were evaluated, and the relationship between its occurrence and permanence in one cerebral hemisphere and the possibility of a seizure-free outcome after surgery were compared. The ictal electroencephalografic and medical records of 284 patients were analyzed. A classification of ictal patterns, whether unilateral or bilateral, was issued, and the seizure outcome after one, two, and five years after surgery annotated. Unilateral ictal patterns occurred in 132 patients, and bilateral ictal patterns in 152. Seizure-free status was obtained in 236 patients, and 48 still persisted with seizures. There was no association between a unilateral ictal status and a seizure-free outcome after surgery (difference of 7.5%, p=0.092; chi-square). So, the electroencephalographic ictal pattern is not a valuable tool for predictions regarding seizure outcome in patients with mesial temporal lobe epilepsy associated with hippocampal sclerosis that are submitted to temporal lobectomy.

Orientadores: Lília Freire Rodrigues de Souza Li, Marcelo Ananias Teocchi / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-26T06:18:40Z (GMT). No. of bitstreams: 1 Ferreira_AnaErikaDias_M.pdf: 2703005 bytes, checksum: 3e71e1e36f3b90f6651557533137b593 (MD5) Previous issue date: 2014 / Resumo: Epilepsia do lobo temporal (ELT) é a forma mais comum de epilepsia em adultos. O processo de epileptogênese inclui a morte neuronal, brotamento axonal, inflamação, neurogênese, estresse oxidativo e gliose. No entanto, os mecanismos moleculares subjacentes não são totalmente compreendidos. Os fatores de crescimento de fibroblastos (FGFs) são uma família de proteínas com várias funções no organismo, especialmente no sistema nervoso central. No entanto, o funcionamento dos FGFs no cérebro humano não é totalmente compreendido. O FGF2 é o membro mais estudado dessa família e seu papel na fisiopatologia da epilepsia é controversa. Na tentativa de esclarecer o envolvimento da via de FGF na ELT, nós quantificamos a expressão hipocampal dos seguintes genes: FGF2, FGF8, FGF22, FGFR1, FGFR2, FGFR3, ITPR3, PIK3R3 e PIK3R5 em 10 pacientes resistentes a fármacos e quatro controles post mortem. Além disso, avaliamos a expressão da proteína de FGF2 por imunofluorescência indireta. Apenas para o FGF2, houve aumento do RNAm no hipocampo dos pacientes para os dois genes de referência testados, HPRT1 e ENO2 + TBP em combinação (P = 0,002 e P = 0,036; respectivamente). A porcentagem de células imunomarcadas para FGF2 no giro dentado foi maior nos pacientes do que nos controles (P <0,05), mas nenhuma alteração significativa foi encontrada no Corno de Ammon. O FGF2 pode preservar os neurônios após lesão e atua como um poderoso fator para a proliferação de células-tronco neurais. Assim, o FGF2 poderia aliviar os danos induzidos pelas crises, intensificar a reparação e reduzir a epileptogênese no hipocampo. Por outro lado, evidências têm demonstrado o envolvimento do FGF2 em mecanismos epileptogênicos, como brotamento de fibras musgosas e neurogênese. Nossos resultados sugerem a participação do FGF2 na fisiopatologia da ELT e o indica como um importante alvo para estudos farmacológicos / Abstract: Temporal lobe epilepsy (TLE) is the most common form of epilepsy in adults. The process of epileptogenesis includes neuronal death, axonal sprouting, inflammation, neurogenesis, oxidative stress and gliosis. However, the molecular mechanisms behind them are not fully understood. Fibroblast growth factor (FGF) gene family encodes proteins with several functions in the organism, especially in the central nervous system. FGF family member functions in the human brain are unclear. To shed light on the involvement of the FGF pathway in TLE, we quantified the hippocampal expression of the following genes: FGF2, FGF8, FGF22, FGFR1, FGFR2, FGFR3, ITPR3, PIK3R3 and PIK3R5 in 10 pharmacoresistant patients and four post mortem controls. We also assessed the FGF2 protein expression by indirect immunofluorescence. Only for FGF2, was the mRNA level markedly increased in patients¿ hippocampi for the two reference genes tested, HPRT1 and ENO2+TBP in combination (P = 0.002 and P = 0.036, respectively). The percentage of FGF2 immunostained cells in the dentate gyrus was higher in patients than in the controls (P <0.05), but no significant alteration was found in the Ammon¿s horn. FGF2 preserves neurons from ongoing injury and acts as a powerful proliferation factor for neural stem cells. It could potentially alleviate seizure-induced damage and intensify repair and reduce epileptogenesis in the hippocampus. On the other hand, evidence has shown FGF2¿s involvement in epileptogenic mechanisms, such as axonal sprouting and neurogenesis. Our results clearly suggest the FGF2 participation in TLE physiopathology and point it out as an important target for pharmacological studies / Mestrado / Saude da Criança e do Adolescente / Mestra em Ciências

Orientador: Fernando Cendes / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-23T22:00:31Z (GMT). No. of bitstreams: 1 Ghizoni_Enrico_D.pdf: 2667786 bytes, checksum: 25592a6b5141d281fe4e92c2e525d68d (MD5) Previous issue date: 2013 / Resumo: Introdução: Os acessos cirúrgicos seletivos no tratamento da epilepsia de lobo temporal (ELT) tem como principal objetivo a ressecção da amígdala e do hipocampo com mínima agressão ao néocortex, ao tronco temporal (TT) e às radiações ópticas. Entre os acessos seletivos, o acesso transuncus (TU) foi recentemente proposto em estudos anatômicos, embora não tenha sido validado clinicamente. O objetivo deste estudo é avaliar a eficiência e segurança do acesso TU no tratamento cirúrgico da ELT. Métodos: Realizou-se estudo prospectivo de pacientes submetidos ao acesso TU. Foram avaliados dados clínicos e radiológicos, sendo os resultados comparados com banco de dados de série histórica de pacientes submetidos a outros dois acessos em nossa instituição, a lobectomia anterior (LA) e a amígdalo- hipocampectomia seletiva através do sulco circular inferior da ínsula (TI). Resultados: Em 25 pacientes submetidos ao acesso TU, a idade média foi de 40±8,21 anos. O seguimento médio foi de 26,44+12,58 meses, com 21 (84%) pacientes classificados como Engel I (bom controle de crises). Não houve diferença significativa quanto ao controle de crises em relação aos grupos submetidos à cirurgia de LA e TI (78,9% e 84,6% respectivamente). Os pacientes submetidos ao acesso TU tiveram, significativamente, menos danos ao TT e às radiações ópticas (p<0,001 e p=0,004 respectivamente) quando comparados aos acessos LA e TI. Entre as complicações do acesso TU, não houve nenhum óbito e apenas um paciente apresentou hemiparesia pós-operatória persistente. Conclusões: Os resultados demonstraram que a amígdalo-hipocampectomia seletiva transuncus é um acesso eficiente e seguro no tratamento cirúrgico da epilepsia do lobo temporal. O acesso TU se mostrou mais seletivo do que os acessos LA e TI com maior preservação do TT e radiações ópticas / Abstract: Introduction: The main objective of the selective approaches on the surgical treatment of the temporal lobe epilepsy (TLE) is to resect the amygdala and hyppocampus with minimal agression to the neocortex, temporal stem (TS) and optic radiations. Anatomic reports have described and proposed the transuncus (TU) approach as a very selective one, but this approach has not been validated in the clinical setting yet. The objective of this study is to evaluate the efficiency and safety of the TU approach in the surgical treatment of the TLE. Methods: A prospective study of patients submitted to the TU approach was performed. Clinical and radiological data were evaluated, and the results were compared with those in our data base about the surgical series of patients operated earlier through two other approaches in our institution, anterior temporal lobectomy (ATL) and selective amygdalohyppocampectomy through inferior circular sulcus of insula (TI). Results: In 25 patients operated through the TU approach the mean age was 40±8,21 years-old. The mean follow-up was 26,44+12,58 months and 21 (84%) patients were classified as Engel I (good seizure control). About the seizure control, there were no significant differences with that of the patients operated through the ATL and TI approaches (78,9% e 84,6% respectively of Enegel I). The patients submitted to the TU approach had, significantly, less injuries to the TS and to the optic radiations (p<0,001 e p=0,004 respectively) when compared to the patients submitted to the ATL and TI approaches. There were no mortality and only one patient had permanent morbidity (residual hemiparesis) in this series. Conclusion: The results showed that the transuncus selective amygdalo-hippocampectomy is an efficient and safe approach in the surgical treatment of the temporal lobe epilepsy. The TU approach showed to be more selective then the ATL and TI approaches with better preservation of the TS and optic radiations / Doutorado / Neurociencias / Doutor em Fisiopatologia Medica

Abstract Epilepsy is associated with changes in autonomic cardioregulatory function. Ictally, autonomic disturbances may be evident with significant changes in heart rate (HR), blood pressure (BP) and respiration. However, interictal dysfunction of autonomic cardiovascular system may be subtle and it may be recognized only by delicate tools designed for that purpose. The aim of this study was to evaluate the function of the cardiovascular autonomic regulatory system in patients with epilepsy. Cardiovascular reflex tests were performed on patients with partial or idiopathic generalized epilepsies. Special attention was paid to temporal lobe epilepsy (TLE). An association of refractory and well controlled TLE and hippocampal sclerosis with altered cardioregulation was evaluated by using cardiovascular reflex tests and an analysis of spectral and non-linear analysis of heart rate variation (HRV). Cardiovascular reflexes were altered both in patients with partial and idiopathic generalized epilepsies who had been treated for epilepsy with antiepileptic drugs (AEDs), whereas patients with newly, untreated epilepsy did not differ from the control subjects. Diminished cardiovascular reflexes also seemed to be associated with carbamazepine (CBZ) treatment. Various parameters of cardiovascular reflex tests and analysis of spectral and dynamic measures of HRV were diminished in patients with TLE compared to the control subejcts. These results indicate that epilepsy, especially TLE, is associated with interictal changes of autonomic cardioregulation. Although these changes seem to be evident in patients with severe form of TLE, patients with well controlled TLE and patients without hippocampal sclerosis also have altered autonomic cardioregulatory function. These results suggest that dysfunction of the cardioregulatory system is rather associated with functional than structural changes of the inner temporal lobe in patients with TLE.

Le kaïnate, est une puissante neurotoxine connue pour induire des convulsions qui rappellent celles trouvées chez les patients atteints d'épilepsie du lobe temporal (ELT). Cependant, le rôle des récepteurs kaïnate activés par le glutamate endogène dans l'ELT n'est pas encore connu. Chez les patients atteints d'ELT et dans les modèles animaux, le tissu neuronal subit une réorganisation majeure. Ce phénomène est particulièrement bien documenté dans le gyrus denté où les axones des cellules granulaires, bourgeonnent pour former un circuit récurrent excitateur aberrant. L'équipe a montré que ces synapses récurrentes moussues nouvellement formées sont aberrantes dans leurs modes de fonctionnement. En effet, en plus des synapses opérant via des récepteurs glutamatergiques de type AMPA présentes en conditions physiologiques, la moitié des synapses aberrantes fonctionnent via des récepteurs de type kaïnate. Les évènements générés par les récepteurs kaïnate ont une cinétique lente, leur permettant de s'intégrer dans une fenêtre temporelle anormalement étendue engendrant un taux de décharge soutenu et fortement rythmique des cellules du gyrus denté de rats épileptiques. L'objectif de mon travail de thèse a été d'étudier l'implication des récepteurs kaïnate dans les activités épileptiques de l'hippocampe. En utilisant différents modèles d'ELT nous avons pu observer que l'absence de ces récepteurs induit une forte diminution de la fréquence des activités épileptiformes dans le gyrus denté in vitro mais également in vivo. Cette étude démontre que les récepteurs kaïnate contenant la sous-unité GluK2 contribuent à la genèse des crises. / Kainate is a potent neurotoxin known to induce acute seizures. However, whether kainate receptors play any role in the pathophysiology of temporal lobe epilepsy (TLE) is not yet known. In animal models of chronic epilepsy, as in human TLE, the hippocampus displays major network reorganization. In particular, sprouting of hippocampal mossy fibers leads to the formation of powerful recurrent excitatory circuits among dentate granule cells, which partly accounts for the enhanced ability of the hippocampus to generate epileptiform activity in human patients and animal models of TLE. At the aberrant recurrent excitatory synapses, mossy fiber inputs impinging on dentate granule cells operate mostly via ectopic kainate receptors and drive synaptic events with abnormal long lasting kinetics not present in naïve conditions. The goal of this work was to explore the pathophysiological implications of kainate receptors in generation of recurrent seizure in TLE through the use of kainate receptors subunit deficient mice and selected pharmacological agents. In an animal model of TLE, we observed a strong reduction of both interictal and ictal activities in the dentate gyrus in vitro and in vivo, in mice lacking the GluK2 subunit, and through the application of a pharmacological agent inhibiting GluK2/GluK5 receptors. Therefore, we demonstrate that aberrant GluK2-containing kainate receptors contribute to chronic seizures in TLE, urging for the development of antiepileptic strategies targeting these receptors.

Ph.D. / Epilepsy is a multidimensional disorder that extends beyond the medical implications to impact nearly every aspect of the person's life, as well as the lives of the people in the surrounding environment. Intractable epilepsy has a poor prognosis with possible worsening of seizures and cognitive decline over time. Anterior temporal lobe surgery for epilepsy provides an opportunity for the alleviation of seizures; however there are potential risks, to memory in particular. Research on surgery outcome thus far has evaluated outcome from a linear paradigm and has studied impact of surgery on isolated areas of function, the results derived from this have been largely inconsistent. So far, there has been very little research that focuses on the person as a whole, and as yet there has been no integrated approach to studying surgical outcome. The aim of the current study was therefore to investigate the impact of anterior temporal lobe surgery, specifically the symptomatic and functional surgical outcomes, in an integrated and holistic manner. This was done in accordance with the paradigm of complex systems theory as a critique of the previous literature in this field, and to gain a more holistic understanding of surgical outcome. A combination of methodologies was employed in order to achieve this. The sample consisted of male (n=10) and female (n=24) patients with intractable epilepsy undergoing left-sided (n=13) and right-sided (n=21) temporal lobe surgery at the Milpark Hospital Johannesburg between the ages of 14 and 58 (mean = 39 years), over a period of seven years. A pretest-posttest design was employed to obtain quantitative data (n=34). Post surgical assessments were conducted up to seven years post surgery (mean=3.6 years). Pre and post surgery assessment included neurocognitive functioning, particularly memory and language functions, by means of the Rey Complex Figure Test, Wechsler Memory Scale-Ill, and Controlled Oral Word Association Test; as well as emotional functioning, particularly depression and anxiety, by means of the Beck Depression lnventory-11 and Beck Anxiety lnventory-11. The quantitative data was subjected to statistical analysis of the sample as a whole, as well as gender and side of surgery comparisons, and included tests of normality of distribution of the data; the paired samples t-test; the independent samples t-test; the Wilcoxon Signed Ranks test; the Mann-Whitney U test; and the Wilks' Lambda test. A semi-structured interview was also conducted (n=30) in order to obtain qualitative data on the functional (psychosocial) aspects of outcome. The interview included an assessment of postoperative seizure outcome; changes in daily activity functions; the client's report on positive and negative outcomes of surgery; quality of life changes and satisfaction with surgery. The qualitative data was analysed using the methods of open coding and axial coding. The results for neuropsychological function reflected known lateralization effects with memory showing auditory-verbal memory deficits after left-sided surgery; and visual (figural) memory deficits after right-sided surgery. Gender differences reflected known neuropsychological differences with female superiority in verbal fluency and a male advantage on visual-spatial tasks. Importantly, there was no relationship between neuropsychological deficit and decrements in daily activity functions, emotional functioning or quality of life. This indicates little impact of neuropsychological deficit post surgery and may be an indication of the effectiveness of the preoperative screening procedures. The results for emotional functioning showed a statistically significant improvement in the 'moderate/severe' depression and anxiety groups from pre to post surgery. This indicates a substantial improvement in both depression and anxiety for this severity group. The qualitative results showed that surgery rendered 74% of the sample seizure free, 15% showing worthwhile improvement, and 11% no change or worse seizures. Seizure outcome however did not determine quality of life changes, even those with some improvement or no change still reported an improvement in quality of life post surgically. The functional outcomes showed little postoperative change in daily activity functions (driving, occupational functioning and marital status) but still a reported improvement in quality of life. There were far more reports on perceived positive than negative outcomes. The most positive benefit of surgery, as reported by participants, was that of increased feelings of control, decreased helplessness, and less anxiety and worry of having seizures. The overwhelming majority of participants reported improved quality of life (90%) and satisfaction with surgery (93%).

L'épilepsie est une maladie fréquente affectant 0,5 à 1% de la population générale. Elle est caractérisée par des crises récurrentes responsables d'un sévère handicap médical et psychosocial. Les causes de l'épilepsie sont multiples et peuvent être liées notamment à des lésions cérébrales anténatales ou acquises, des causes génétiques ou métaboliques. L'épilepsie du lobe temporal (ELT) est la forme la plus répandue chez l’adulte, le plus souvent associée à une sclérose de l'hippocampe et réfractaire aux traitements antiépileptiques. Si pendant longtemps l'ELT a été perçue comme une pathologie focale centrée sur l'hippocampe sclérosé, de nombreux travaux montrent que les atteintes associées à l'ELT s'étendent bien au-delà de l'hippocampe et du lobe temporal, suggérant une altération plus globale du réseau cérébral structurel impactant le fonctionnement du cerveau. Toutefois, ces atteintes sont encore mal connues. Le développement récent des séquences et du traitement de l’imagerie de diffusion permettent l’acquisition d’images anatomiques du cerveau et la modélisation des fibres de substance blanche. L’architecture du réseau cérébral peut alors être représentée mathématiquement par un graphe, appelé « connectome » structurel, définissant la force des liens structurels (fibres de substance blanche) entre différentes régions du cerveau.L’objectif principal de la thèse est d’identifier les altérations du réseau structurel liées à l’épilepsie, avec un intérêt particulier à l’ELT. L’objectif secondaire est de développer de nouvelles méthodes d’extraction du connectome structurel pour en améliorer la précision anatomique et mieux identifier et localiser les altérations du réseau structurel.Ainsi, dans un premier temps, nous établissons l’état de l’art des méthodes d’extraction et d’analyse du connectome structurel et discutons leurs limites. Nous présentons alors une nouvelle méthode d’extraction du connectome structurel haute-résolution couvrant l’ensemble du cortex et incluant certaines régions sous-corticales, baptisée « high-resolution structural connectome ». L’objectif est de définir un cadre d’analyse du connectome structurel avec une très bonne précision anatomique et de fournir les outils nécessaires pour des études individuelles ou de groupe en tenant compte des contraintes de temps de calcul et d’utilisation de la mémoire et du disque.Dans un deuxième temps, nous analysons le connectome structurel de patients ELT avec sclérose hippocampique latéralisée dans le but de mettre en évidence le réseau structurel pathologique et d’en distinguer les caractéristiques en fonction de la latéralité de la lésion. Nous validons la stabilité et la reproductibilité du connectome structurel haute-résolution sur des sujets sains. La démonstration de son intérêt clinique potentiel est apportée en observant des différences structurelles subtiles entre deux groupes de sujets sains et en identifiant les sous-structures du striatum. Enfin, notre méthode est appliquée dans un contexte clinique pour identifier les altérations de connectivité structurelle du complexe hippocampo-amygdalien, impliqué dans l’ELT, en lien avec la pathologie. Nos travaux ont ainsi permis d’identifier les altérations globales et diffuses du réseau structurel liées à l’ELT, et plus particulièrement ont mis en évidence des disparités importantes selon la latéralité de la pathologie. Nous avons également présenté une nouvelle méthode d’extraction du connectome structurel augmentant considérablement sa précision anatomique et défini les outils nécessaires à l’analyse haute-résolution du connectome structurel. L’intérêt de cette méthode a été démontré par le gain de précision anatomique obtenu pour l’étude de l’architecture cérébrale du sujet sain ou pour une meilleure identification de réseaux pathologiques, ouvrant ainsi de nombreuses perspectives sur la caractérisation de l’architecture cérébrale et son lien sur le fonctionnement du cerveau. / Epilepsy is a frequent disease affecting 0.5 to 1% of the general population, characterized by recurrent seizures responsible for severe medical and psychosocial handicaps. The causes of epilepsy may be antenatal or acquired brain lesions, genetic history or metabolic disorders. Temporal lobe epilepsy (TLE) is the most common medically intractable epilepsy in adults, often associated with hippocampal sclerosis. Although TLE has been perceived for a long time as a hippocampal disorder, many studies show that the disease actually affects brain regions beyond the hippocampus and temporal lobe suggesting diffuse alteration of the brain structural network. However, these alterations are still unknown. Recent advances in diffusion weighted imaging and processing allow for the acquisition of brain anatomical images and the modeling of white matter fibers. Brain network architecture can then be represented mathematically by means of a graph, called “structural connectome”, defining the strength of the structural links (white matter fibers) across brain regions.The purpose of this thesis is to identify structural network alterations associated with epilepsy, in particular TLE. The secondary objective is to develop new methods for extracting the structural connectome in order to increase the anatomical accuracy and better localize network alterations.Therefore, we first review the state of the art of the methods used for extracting and analyzing the structural connectome and establish their limitations. We then introduce a new method to extract the structural connectome with increased anatomical accuracy, which we called “high-resolution structural connectome”. The purpose is to provide a framework to analyze brain connectivity at high-resolution and to define the necessary tools for individual and group analysis, keeping in mind processing time and memory and disk usages.Then, we analyze the structural connectome of TLE patients with hippocampal sclerosis to reveal underlying pathological network, we also highlight pathological network discrepancies between left and right sided lesions. Inter- and intra-subject stability and repeatability of the high-resolution structural connectome are assessed with a cohort of healthy subjects. We demonstrate potential clinical interest by observing subtle structural differences between two groups of healthy subjects and by delineating the sub-fields of the striatum. Finally, our method is applied to the pathological case of TLE and aims at uncover structural connectivity alterations of the hippocampo-amygdalian complex, known to be involved in TLE.In conclusion, we extend our current knowledge on TLE by showing that this is a network disease involving widespread brain regions, whose pattern largely depends on lesion laterality. We also introduce a new method for extracting the structural connectome at high-resolution, considerably increasing the anatomical accuracy. The interest of this method is demonstrated on healthy subjects to better characterize the healthy brain and on the diseased brain to localize more precisely the brain regions associated with the pathology.

This dissertation investigates the mechanisms underlying pattern separation, using rodent models and behavioural tasks that assess the use of representations for similar stimuli. Pattern separation is a theoretical mechanism involving the transformation of inputs into output representations that are less correlated to each other. Because of this orthogonalizing process, similar experiences are stored as discrete non-overlapping representations. Studying pattern separation emphasizes the important but often overlooked fact that successful memory involves more than just remembering events over a period of time, but also differentiating between similar memories. Through a series of experiments this dissertation adds support to the literature that the dentate gyrus (DG) subregion of the hippocampus is important for pattern separation when encoding spatial and contextual inputs. Using the Spontaneous Location Recognition (SLR) task it is shown the brain-derived neurotrophic factor (BDNF) can improve performance by acting via N-methyl-D-aspartate (NMDA) glutamate receptors in the DG and adult-born hippocampal neurons. Manipulating the level of neurogenesis by inhibiting Wnt signalling or by administering acyl-ghrelin systemically is shown to impair and enhance performance on SLR, respectively. Using a novel exposure paradigm in combination with SLR, it is demonstrated for the first time that the relationship between pattern separation and neurogenesis may be reciprocal, such that inhibiting neurogenesis impairs pattern separation, enhancing neurogenesis improves pattern separation, and performing pattern separation enhances the production or survival of adult-born hippocampal neurons. Finally, it is shown that the $TgTau^{P301L}$ mouse model of dementia exhibits spatial and object recognition memory impairments once aged, recapitulating a dementia-like phenotype. Understanding the mechanisms that contribute to effective pattern separation may help elucidate the processes underlying the memory impairment experienced by AD patients. This dissertation concludes with a critical discussion about whether pattern separation can be studied using behavioural paradigms.

Les chansons lient naturellement des mélodies à des paroles. Elles représentent l’une des formes les plus utilisées de l’expression musicale. De façon intéressante, les chansons nécessitent l’intégration simultanée d’informations verbales (les paroles) et d’informations musicales (la mélodie) pour former une seule trace mnésique. Le lobe temporal médian a été identifié comme région clé pour la mémoire épisodique et en particulier pour le processus de binding, qui consiste en la liaison de plusieurs éléments d’un souvenir. Néanmoins, les mécanismes par lesquels le cerveau réalise la liaison entre paroles et mélodies dans la mémoire des chansons restent peu connus. L’objectif de cette thèse est de montrer le rôle du lobe temporal médian dans le processus de binding de paroles et mélodies pour la création d’un souvenir unifié d’une chanson. Premièrement, nous avons étudié les effets d’une sclérose unilatérale de l’hippocampe associée à une épilepsie du lobe temporal sur le processus de mémorisation des chansons en IRM fonctionnelle (étude 1). Les patients avec une sclérose de l’hippocampe gauche avaient un déficit d’adaptation aux paroles et de la représentation intégrée des chansons. Puis, nous avons étudié l’organisation fonctionnelle de la mémoire des chansons dans une étude d’IRM fonctionnelle chez des volontaires sains (étude 2). Les résultats ont montré l’implication de l’hippocampe dans le processus de binding en mémoire des chansons ainsi que l’implication d’autres structures comme le gyrus frontal inférieur, les ganglions de la base et le cervelet. Enfin, dans une dernière étude (étude 3), nous avons examine la mémoire des chansons et plus particulièrement la mémoire de l’association (binding) des paroles au contexte musical chez des patients ayant bénéficié d’une résection unilatérale du lobe temporal médian pour traiter une épilepsie pharmacorésistante. La mémoire des paroles ainsi que celle du contexte mélodique des chansons a été testé dans une tâche explicite de reconnaissance. Un fort déficit en reconnaissance de paroles a été constaté chez les patients avec une lésion temporale gauche, et à un moindre degré chez les patients avec une lésion temporale droite. Ce déficit a été corrélé avec des déficits de la mémoire verbale. L'étude 3 suggère, en outre, que les structures du lobe temporal médian peuvent être cruciales pour le codage de la liaison détaillée entre les paroles et leur contexte mélodique, tandis que les effets implicites d'une représentation intégrée de la chanson peuvent être épargnés après des lésions du lobe temporal médian. Pour conclure, ces trois études ont apporté de nouvelles données sur le rôle du lobe temporal médian dans le processus de binding dans le domaine musical. Ce travail a également permis d’identifier un vaste réseau de régions corticales et sous-corticales impliqué dans l’encodage de nouvelles chansons avant de discuter les implications théoriques et cliniques de ces recherches. / Songs naturally couple music with language, constituting one of the most broadly used forms of music expression. Interestingly, songs require the simultaneous and integrated process of verbal (lyrics) and musical (melody) information to form a single memory trace. The medial temporal lobe has been identified as the key region for the integration of features of an event in episodic memory, also called the binding function. Nevertheless, the mechanisms by which the brain binds lyrics and melodies in song memory remain poorly understood. The purpose of this thesis is to elucidate the role of the MTL on the binding of lyrics and melodies for the creation of a unified song memory trace. First, the effects of unilateral hippocampus sclerosis on song processing were investigated in an fMR-adaptation study (Study 1). Patients with left hippocampal sclerosis showed adaptation deficits in response to lyrics as well as to the integrated representation of songs. To further explore the relation of these results with the emergence of memory for songs, the functional architecture of song memory was examined in a subsequent memory fMRI study (Study 2). The results support the implication of the hippocampus in song binding. Furthermore, the role of other structures, including the Inferior Frontal Gyrus (IFG), the Basal Ganglia (BG) and cerebellum was highlighted and discussed. Finally, Study 2 was adapted to test binding in patients following a unilateral temporal lobe excision for the relief of intractable temporal lobe epilepsy behaviorally in Study 3. Memory for lyrics as well for their melodic context was tested in an explicit recognition task. A strong deficit in lyrics recognition was found in patients with a left temporal lesion, and to a smaller degree in patients with a right temporal lesion. This deficit was correlated with deficits in verbal memory. Evidence from Study 3 further suggests that MTL structures may be crucial for encoding the detailed binding of lyrics with their melodic context, whereas implicit effects of an integrated representation of the song may be spared after MTL lesions. Altogether the studies presented in this thesis provide novel evidence for the role of the medial temporal lobe structures in binding lyrics and melodies for song memory. The present thesis proposes a comprehensive network of cortical and subcortical regions cooperating to successfully encode new songs. Finally, theoretical and clinical implications of these findings are considered.