O esquecimento intencional pode cumprir uma função estratégica no sistema cognitivo, que permite aos indivíduos não pensar sobre acontecimentos indesejados do passado, tais como eventos traumáticos, dolorosos e violentos, dos quais se prefere não recordar. Enquanto esquecer involuntariamente é uma falha da lembrança, por outro lado, esquecer intencionalmente parece ser uma função estratégica da memória. A presente dissertação teve por objetivo investigar os mecanismos neurocognitivos que contribuem para o esquecimento de memórias. A dissertação se organizou em dois estudos. O primeiro estudo consiste em uma revisão sistemática de artigos empíricos publicados nos últimos dez anos sobre a supressão de memórias indesejadas. O segundo estudo é um ensaio empírico, no qual foi executado um experimento adaptado do paradigma Think/No-Think com a utilização de marcadores eletrofisiológicos de eletroencefalograma. Participaram do experimento 22 sujeitos, alocados aleatoriamente em dois grupos com estratégias distintas de esquecimento: Supressão de memória e substituição de pensamentos. Durante toda a tarefa experimental, os participantes tiveram dados de EEG continuamente gravados. Os resultados decorrentes do ensaio empírico estão de acordo com os achados da literatura, indicando que a positividade parietal em torno de 400-800ms após a apresentação do estímulo é um marcador de lembrança consciente durante a recuperação de memória. Apenas na estratégia de supressão de memória houve uma redução da positividade centro-parietal durante o esquecimento, entre 450 e 700ms após apresentação do estímulo. Além disso, uma maior deflexão no componente N2 durante a supressão é um preditor de esquecimento induzido. Os achados indicam que é possível mapear o sistema neurocognitivo subjacente à supressão de memórias. / Intentional forgetting can be characterized as a strategic function of the cognitive system that allows us not to think about unwanted memories from our past, as for example emotional events or traumatic experiences that we would prefer not to remember. While forgetting involuntarily is a failure of recollection, on the other hand, forgetting intentionally seems to be a strategic function of memory. The aim of this dissertation was to investigate the neurocognitive mechanisms that contribute to forgetting memories. The dissertation was organized in two studies. The first study consists of a systematic review of empirical articles published in the last ten years on the suppression of unwanted memories. The second study is an empirical essay, in which an experiment adapted from the Think/No-Think paradigm was performed, with the use of electrophysiological markers of electroencephalogram. Twenty-two subjects participated in the experiment, randomly assigned to two groups with distinct strategies of forgetting: Memory suppression and thought substitution. Throughout the experimental task, participants had continuously recorded EEG data. The results of the empirical essay are in agreement with the literature findings, indicating that the parietal positivity around 400-800 ms after the presentation of the stimulus is a marker of conscious memory during memory recovery. Only direct memory suppression reduced centro-parietal positivity during forgetting, between 450 and 700 ms post-stimulus. Also, a greater deflection in the N2 component during suppression is an induced forgetting predictor. The findings indicate that it is possible to map the neurocognitive system underlying memory suppression.

Introduction: Osteoporosis belongs to multifactorial metabolic skeletal disease. The breast carcinoma is one of the most common malignities in women worldwide (with an exception of skin tumours). Postmenopausal women with non-metastatic breast carcinoma, which are treated with aromatase inhibitors (AI), have increased risk of developing osteoporosis. In these patients, it is necessary to identify the factors contributing to onset of osteoporosis which can be influenced, and take protective measures towards bone metabolism, in order to reduce the occurrence of serious low-traumatic fractures. Objective: The objective of this thesis is to evaluate the diet with regard to risk factors leading to osteoporosis and bone fractures in postmenopausal women with breast carcinoma without metastases, which are treated with AI. Another objective for this group of women is to evaluate the changes of bone mineral density (BMD) and certain parameters of body composition during long-term treatment of AI. Methods: The present study is based on a questionnaire containing a table to quote a three day diet, which was subsequently analysed to identify the overall energetic income, the income of proteins, fat, carbohydrates, dietary fibre and calcium. The supply of vitamin D was deduced for the serum concentration of...

A ciência e tecnologia andam juntas. A ciência fornece o conhecimento para a geração de novas tecnologias que, porsua vez, disponibiliza novas ferramentas para a geração de novos conhecimentos. Uma educação científica deve vir acompanhada de uma educação tecnológica permitindo então que o aluno entenda não só o experimento, mas também como os resultados foram obtidos, como os equipamentos, técnicas e protocolos funcionam. Para uma educação científica efetiva o aluno deve ir além de expectador, se colocando no papel de pesquisador, a fim de construir seu próprio conhecimento. No entanto, para essa tarefa, é necessário o uso de equipamentos adequados ao experimento a ser realizado. Essa tese visa suprir a necessidade de equipamentos para experimentos na área de neurociência focados no estudo de memória e aprendizado, utilizando roedores e peixes como modelos animais na tarefa de esquiva inibitória passiva. Esses equipamentos visam uma maior acessibilidade do ponto de vista operacional e financeiro, sendo mais precisos e com isso fornecendo dados mais confiáveis e robustos do que os equipamentos disponíveis. Possibilitando aos alunos, da alfabetização à pós-graduação, a realização de experimentos comportamentais, tanto de maneira simples quanto complexas, interagindo em todas as etapas experimentais, resultando em aprendizagem e desenvolvimento cognitivo além de possibilitar novas descobertas científicas. / Science and technology walking together, science provides the knowledge to generate new technologies which in turn provides new tools for the generation of new knowledge. A science education must be accompanied by a technological education to enable students to understand not only the experiment, but also how the results were obtained, understanding how the equipment, techniques and protocols work. For effective science education the student must go beyond bystander, putting themselves in the researcher function in order to construct their own knowledge. However for this task, it is necessary to use suitable equipment to the experiment to be performed. This PhD Thesis aims to fill a need for equipment for experiments in neuroscience focused on the study of memory and learning, using rodents and fish as animal models in the passive inhibitory avoidance task. These devices achieve greater accessibility of the operational and financial point, being more accurate and thus providing more reliable and consistent data that current equipment. Enabling student’s literacy to post graduate conducting simple and complex behavioral experiments, interacting in all experimental steps, resulting in learning and cognitive development and enable new scientific discoveries.

Neste estudo avaliamos atividades biológicas pré-clínicas de moléculas obtidas de Mangifera indica e de Valeriana glechomifolia. Mangiferina, isolada de M. indica, estimulou a proliferação celular e induziu um aumento significativo na secreção do fator de crescimento do nervo e do fator de necrose tumoral em células de glioblastoma humano U138-MG in vitro. Uma injeção sistêmica de mangiferina melhorou a consolidação da memória de longa duração (LTM) de reconhecimento de objetos (RO) e prejudicou a retenção da memória aversiva no teste da esquiva inibitória (EI) em ratos. A melhora da LTM no RO promovida pela administração sistêmica de mangiferina também foi observada com a administração intrahipocampal. Já o prejuízo da memória no teste da EI observado sistemicamente não ocorreu com a infusão no hipocampo ou amígdala. Camundongos atáxicos também apresentaram melhora na memória de RO após administração crônica de mangiferina, sem efeito na EI; um extrato comercializado de M. indica não afetou a memória no RO, mas facilitou a memória na EI. Os resultados indicam que mangiferina melhora a LTM no RO com envolvimento do hipocampo por meio de um mecanismo que pode envolver um aumento dos níveis da neurotrofina NGF e da citocina TNF-α. Valepotriatos, isolados de V. glechomifolia, demonstraram inibição da viabilidade de células tumorais U138-MG nas doses de 30 e 100μg/μl; o 8-Br- AMPc, um análogo do AMPc, atenuou à inibição dos valepotriatos na viabilidade celular, sugerindo que os valepotriatos interagem com a rota de sinalização celular do AMPc/PKA na inibição da viabilidade de células cancerosas. A administração sistêmica de valepotriatos, em camundongos 30 minutos antes dos testes, apresentou os seguintes resultados: durante a exploração no campo aberto, a dose 10mg/kg causou redução na locomoção e no comportamento exploratório e diminuição da ansiedade no teste do labirinto em cruz elevado. Não ocorreu diferença entre os tratamentos na memória de EI e na memória RO, exceto no grupo que recebeu 3mg/kg de valepotriatos que apresentou piora na LTM de RO. Os resultados indicam que os valepotriatos causaram atividades ansiolítica e sedativa sem déficits na memória de EI e RO em camundongos tratados com 10mg/kg. As atividades biológicas in vitro e in vivo encontradas nas moléculas estudadas (especialmente mangiferina e valepotriatos) geram interesse de investigações para utilizações terapêuticas na memória e no câncer. / We evaluated the biological activities of molecules obtained from Mangifera indica and Valeriana glechomifolia. Mangiferin, isolated from M. indica, stimulated cell proliferation and induced a significant increase in levels of nerve growth factor and tumor necrosis factor secreted in human glioblastoma cells U138-MG in vitro. A systemic injection of mangiferin improved long term memory (LTM) consolidation of object recognition (NOR) and impaired memory retention in aversive inhibitory avoidance test (IA) in rats. The improvement in NOR memory promoted by systemic administration of mangiferin was also observed with intrahippocampal administration. The memory impairment observed systemically in the IA did not occur with the infusion into the hippocampus or amygdala. Ataxic mice also showed improvement in NOR memory after chronic administration of mangiferin, with no effect on IA; a standardized extract of M. indica had not effect on memory in NOR, but facilitated the memory in IA. The results indicate that mangiferin improvement NOR memory involving the hippocampus through a mechanism that may involve increased levels of neurotrophins and cytokines. Valepotriates isolated from V. glechomifolia showed inhibition of the viability of U138-MG tumor cells at doses of 30 and 100μg/μl; 8-BrcAMP, an analogue of cAMP, reversed the inhibition of valepotriates on cell viability, suggesting that valepotriates interact with the cAMP/PKA signaling route in the inhibition of the viability of cancer cells. Systemic administration of valepotriates in mice, 30 minutes before tests, showed the following results: during the open-field, the dose of 10mg/kg caused a reduction in locomotion and exploratory behavior and decreased anxiety in the test of elevated plus maze. There was no difference between treatments in IA or NOR memories, except from the group receiving valepotriates at 3mg/kg, which worsened in the NOR. The results indicated that valepotriates at 10mg/kg caused anxiolytic and sedative activities without inducing memory deficits in IA and NOR. The biological activities in vitro and in vivo found with the studied molecules (notable mangiferin and valepotriates) support further research for potential therapeutic uses in cancer and in memory.

A ciência e tecnologia andam juntas. A ciência fornece o conhecimento para a geração de novas tecnologias que, porsua vez, disponibiliza novas ferramentas para a geração de novos conhecimentos. Uma educação científica deve vir acompanhada de uma educação tecnológica permitindo então que o aluno entenda não só o experimento, mas também como os resultados foram obtidos, como os equipamentos, técnicas e protocolos funcionam. Para uma educação científica efetiva o aluno deve ir além de expectador, se colocando no papel de pesquisador, a fim de construir seu próprio conhecimento. No entanto, para essa tarefa, é necessário o uso de equipamentos adequados ao experimento a ser realizado. Essa tese visa suprir a necessidade de equipamentos para experimentos na área de neurociência focados no estudo de memória e aprendizado, utilizando roedores e peixes como modelos animais na tarefa de esquiva inibitória passiva. Esses equipamentos visam uma maior acessibilidade do ponto de vista operacional e financeiro, sendo mais precisos e com isso fornecendo dados mais confiáveis e robustos do que os equipamentos disponíveis. Possibilitando aos alunos, da alfabetização à pós-graduação, a realização de experimentos comportamentais, tanto de maneira simples quanto complexas, interagindo em todas as etapas experimentais, resultando em aprendizagem e desenvolvimento cognitivo além de possibilitar novas descobertas científicas. / Science and technology walking together, science provides the knowledge to generate new technologies which in turn provides new tools for the generation of new knowledge. A science education must be accompanied by a technological education to enable students to understand not only the experiment, but also how the results were obtained, understanding how the equipment, techniques and protocols work. For effective science education the student must go beyond bystander, putting themselves in the researcher function in order to construct their own knowledge. However for this task, it is necessary to use suitable equipment to the experiment to be performed. This PhD Thesis aims to fill a need for equipment for experiments in neuroscience focused on the study of memory and learning, using rodents and fish as animal models in the passive inhibitory avoidance task. These devices achieve greater accessibility of the operational and financial point, being more accurate and thus providing more reliable and consistent data that current equipment. Enabling student’s literacy to post graduate conducting simple and complex behavioral experiments, interacting in all experimental steps, resulting in learning and cognitive development and enable new scientific discoveries.

The phosphatidylinositol-3-kinase (PI3K) signalling pathway is evolutionarily conserved in all eukaryotes and its main function is the regulation of autophagy and protein sorting to the vacuole/lysosome. In the pathogenic yeast species Candida albicans and Cryptococcus neoformans the PI3K signalling pathway is required for virulence. In the yeast Saccharomyces cerevisiae the PI3K signalling pathway consists of two proteins - phosphatidylinositol-3-kinase, Vps34p and its regulator Vps15p. In this diploma thesis I analyse the role of the PI3K signalling pathway in the growth and development of colonies of natural and laboratory strains. I proved that VPS34 or VPS15 deletion in haploid laboratory strains has a significant influence on colony size and invasive growth (in strain ΣSh vps15Δ). Deletion of VPS34 or VPS15 also increases sensitivity of cells to oxidative stress and detergents. Attempts to delete VPS34 in natural strains were unsuccesful, probably because VPS34 is essential in these strains. Constitutive expression of VPS34 does not affect cell resistance in inhibitory tests, the size and differentiation of colonies or ammonia signalling but differences are notable in giant colony morphology and in patterns of invasiveness of the medium. Tagging of the C-terminal of Vps34p with GFP affects...

Les projections corticales de retour conduisent l'information vers des relais de traitement de l'information plus précoces. Elles sont essentielles pour la perception sensorielle. En ce qui concerne l'olfaction, l'information sensorielle est constituée d'une multitude de molécules odorantes, et c'est ce mélange complexe qui pénètre dans la cavité nasale. En fonction du contexte, c'est une partie ou une autre de cet ensemble de molécules qui va être importante d'un point de vue comportemental. Les signaux corticaux de retour permettraient de focaliser son attention sur les odeurs pertinentes de l'environnement. Au cours de mon doctorat, j'ai étudié le rôle de la signalisation inhibitrice GABAergique dans ces retours corticaux vers le bulbe olfactif, le premier relais de l'information olfactive. La première partie de mon travail a mis en évidence une modulation métabotropique GABAergique du retour cortical excitateur. Nos expériences caractérisent ensuite l'effet produit par cette modulation sur le bulbe olfactif. Nous avons ainsi démontré que la signalisation GABAergique au niveau de retours corticaux change de manière profonde la réponse du bulbe olfactif aux stimuli olfactifs. Dans un deuxième temps, j'ai trouvé que le cortex olfactif envoie non seulement des projections de retour excitatrices, mais aussi des retours inhibiteurs. Des expériences précisent ensuite la localisation de ce retour GABAergique, ainsi que son impact sur le bulbe olfactif. Nous avons notamment observé qu'en manipulant l'activité de ces fibres GABAergiques, nous pouvions modifier le comportement olfactif. / Cortical feedback conducts information towards earlier relays of information processing. It is instrumental for sensory perception. In the olfactory system, odorants are never experienced in isolation by the nose, and they might be meaningful to the animal or not depending on the context. Feedback inputs onto early processing stages are poised to permit selective attention to the relevant odorants in the olfactory scene. During my thesis work, I focused on understanding the key role that inhibitory GABAergic signaling plays in the cortical feedback to the olfactory bulb in mice.The first part of my work started with the discovery of excitatory transmission between cortical feedback inputs and the olfactory bulb is modulated by metabotropic receptors for GABA. Next, the impact of this regulation on the olfactory bulb network was investigated. We found that GABAergic signaling at cortical feedback axons profoundly changes the response of the olfactory bulb output cells to odor stimulation. In the second part of my thesis, I found that the cortical projections to the olfactory bulb not only comprises of excitatory components, but also inhibitory components. The precise origin of this GABAergic feedback was then determined and its impact on the olfactory bulb network is currently assessed. In particular, we observed that manipulating the activity of this GABAergic feedback perturbs olfactory behavior.

Cocaine users display impaired inhibitory control. The influence of cocaine-related stimuli on inhibitory control has not been assessed. The Attentional Bias-Behavioral Activation (ABBA) task uses cocaine and neutral images as cues to determine if drug-related images impair inhibitory control in cocaine users. This dissertation was designed to assess the influence of cocaine images on inhibitory control in cocaine users through the conduct of studies designed to address four aims. The first aim was to demonstrate that cocaine users display impaired inhibitory control following cocaine images compared to neutral images on the ABBA task. This was accomplished through the conduct of two experiments. The first experiment piloted the ABBA task and cocaine users completed the cocaine go (n = 15) or neutral go condition (n = 15) of the task. The second experiment consisted of two studies designed to develop a within-subjects methodology for using the ABBA task. In the first study, cocaine users completed either the cocaine go (n = 20) or neutral go (n = 20) condition of the ABBA task and all participants also completed the Cued Go/No-Go task, with geometric shapes as cues. In the second study, cocaine users (n = 18) completed the cocaine go condition of the ABBA task and a modified version of the ABBA task with all neutral images as cues to further refine a possible within-subjects methodology. The second aim was to demonstrate that inhibitory failures occur most often when cues are presented for short compared to longer durations of time. Data collected during other protocols (n = 91) were combined to investigate the influence of stimulus onset asynchrony (SOA; i.e., the amount of time a cue is presented before a target indicated a response should be executed or withheld) on inhibitory control following cocaine-related and neutral cues on the ABBA task. The third aim was to demonstrate impaired inhibitory control following cocaine images on the ABBA task is specific to cocaine users. Cocaine users (data collected in the second experiment of the first aim) and non-using control participants (n = 16) completed the cocaine go and all neutral conditions of the ABBA task and the Cued Go/No-Go task. The fourth aim was to demonstrate the feasibility and acceptability of inhibitory control training to cocaine-related stimuli with cocaine users. A small pilot clinical trial was conducted and cocaine users were randomly assigned to complete inhibitory control training to cocaine images or geometric shapes. Cocaine images impaired inhibitory control on the ABBA task, as demonstrated by an increased proportion of inhibitory failures in the cocaine go condition compared to the neutral go condition in Experiments 1, 2, and 4. The proportion of inhibitory failures following cocaine images in Experiment 4 was increased at short (i.e., 100, 200) compared to long SOAs. Cocaine images also impaired inhibitory control compared to the Cued Go/No-Go Task in Experiment 2, however there were no differences in the proportion of inhibitory failures between the cocaine go and all neutral conditions of the ABBA task. There were no differences between cocaine users and controls in Experiment 3 for the proportion of inhibitory failures on the ABBA or Cued Go/No-Go tasks, but controls responded faster indicating a speed/accuracy trade off occurred in the control group. Inhibitory control training as an approach to improve treatment outcomes is feasible, as indicated by attendance and accuracy on the training task, and participants rated the overall procedure as satisfactory in Experiment 5. A better understanding of inhibitory control in the presence of cocaine related cues could be crucial to better understand how drug cues contribute to the risk for relapse and the continued use of drugs because both occur in the presence of drug cues.

Schistosoma mansoni est un parasite helminthe responsable de la schistosomiase intestinale, qui affecte 200 millions de personnes dans les zones tropicales et subtropicales, et l’on estime que 600 millions de personnes sont exposées au risque de cette infection. Le cycle de vie du parasite est complexe et il requière, un hôte définitif, l’homme et un hôte intermédiaire, un mollusque d’eau douce appelé Biomphalaria glabrata. C’est chez le mollusque où le parasite se multiplie de forme massive de là l’importance du mollusque dans la transmission du parasite à l’homme. Lors de l’infection le mollusque met en place une réponse cellulaire et humorale très marquées pouvant dans certains cas tuer le parasite. Malgré l’importance du mollusque, les mécanismes moléculaires qui gouvernent ces réponses sont largement inconnus et donc l’étude de l’immunité du mollusque est une priorité en recherche médicale. Nous avons identifié deux orthologues de la cytokine de mammifère MIF (Macrophage Migration Inhibitory Factor ) BgMIF1 et BgMIF2. En utilisant des approches biochimiques et moléculaires en combinaison avec la technique de RNAi in vitro et in vivo nous avons démontré le rôle de BgMIF 1 et BgMIF2 comme régulateurs centrales de l’immunité innée du mollusque. En particulaire BgMIF1 régule l’activation des hémocytes et la réponse d’encapsulation lors de l’infection. D’un autre côté BgMIF2 régule dans la réponse antibactérienne. Nos résultats montrent que chez B. glabrata il y une régulation fine de la réponse immune innée et une capacité pour répondre de façon différente lors d’un challenge immunitaire. De plus une régulation par une cytokine de type vertébré dans un invertébré n’avait jusqu’à présent jamais été décrite. Nos travaux établissent les bases pour mieux comprendre les relations hôte-parasite dans une maladie comme la schistosomiase, et aussi constituent une avancée importante du point de vue de l’évolution de l’immunité innée en général.l / We have identified and characterized a Macrophage Migration Inhibitory Factor (MIF) family member in the Lophotrochozoan invertebrate, Biomphalaria glabrata, the snail intermediate host of the human blood fluke Schistosoma mansoni. In mammals, MIF is a widely expressed pleiotropic cytokine with potent pro-inflammatory properties that controls cell functions such as gene expression, proliferation or apoptosis. Here we show that the MIF protein from B. glabrata (BgMIF) is expressed in circulating immune defense cells (hemocytes) of the snail as well as in the B. glabrata embryonic (Bge) cell line that has hemocyte-like features. Recombinant BgMIF (rBgMIF) induced cell proliferation and inhibited NO-dependent p53-mediated apoptosis in Bge cells. Moreover, knock-down of BgMIF expression in Bge cells interfered with the in vitro encapsulation of S. mansoni sporocysts. Finally, the in vivo knock-down of BgMIF prevented the changes in circulating hemocyte populations that occur in response to an infection by S. mansoni miracidia. These results provide the first functional evidence that a MIF ortholog is involved in an invertebrate immune response towards a parasitic infection and highlight the importance of cytokines in invertebrate-parasite interactions.

Background: While pain is essential for physiological functioning, chronic or pathologic pain is responsible for a major burden of disease in society. Novel approaches to treating acute and chronic pain have employed neuromodulatory tools to target the central and peripheral neural structures that mediate pain. Transcranial direct current stimulation (tDCS), for example, is a safe, non-invasive brain stimulation technique that has been shown in preliminary studies to reduce chronic pain when applied to the primary motor cortex. In contrast to this exogenous neuromodulatory approach, diffuse noxious inhibitory controls (DNIC) refers to endogenous pain regulatory mechanisms that decrease pain following introduction of heterotopic noxious stimuli. This thesis explores whether combining these exogenous and endogenous pain modulation approaches synergistically increases the threshold at which pain is perceived. Methods: We conducted a double-blinded, randomized, placebo-controlled trial with a crossover design to investigate the effects of tDCS and DNIC on pain thresholds in 15 healthy human subjects. Pain thresholds were assessed prior to and following administration of active tDCS, sham tDCS, cold-water-induced DNIC, and combined active tDCS and DNIC. Using magnetic resonance spectroscopy, we examined whether baseline concentrations of brain metabolites such as N-acetylaspartate in pain-related regions of interest were associated with responses to the varying neuromodulatory conditions. Results: Pain thresholds significantly increased following both active tDCS and the DNIC paradigm. These modulatory approaches appeared to have additive effects when combined. Pain threshold increases after active tDCS were positively correlated with baseline levels of N-acetylaspartate, a marker of good neural function, in the anterior cingulate cortex and negatively correlated with baseline levels of glutamine in the thalamus. Conclusions: Combining endogenous pain regulatory mechanisms with exogenous stimulation of the motor cortex can more effectively increase pain thresholds in healthy humans. Future studies should examine whether existing pain therapies may be enhanced with noninvasive brain stimulation and activation of DNIC. They should also assess whether brain metabolite levels can be utilized to predict clinical response to therapeutic interventions.