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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Influence of frequent nightmares on REM sleep-dependent emotional memory processing

Carr, Michelle 04 1900 (has links)
La littérature suggère que le sommeil paradoxal joue un rôle dans l'intégration associative de la mémoire émotionnelle. De plus, les rêves en sommeil paradoxal, en particulier leur nature bizarre et émotionnelle, semblent refléter cette fonction associative et émotionnelle du sommeil paradoxal. La conséquence des cauchemars fréquents sur ce processus est inconnue, bien que le réveil provoqué par un cauchemar semble interférer avec les fonctions du sommeil paradoxal. Le premier objectif de cette thèse était de reproduire conceptuellement des recherches antérieures démontrant que le sommeil paradoxal permet un accès hyper-associatif à la mémoire. L'utilisation d'une sieste diurne nous a permis d'évaluer les effets du sommeil paradoxal, comparativement au sommeil lent et à l’éveil, sur la performance des participants à une tâche sémantique mesurant « associational breadth » (AB). Les résultats ont montré que seuls les sujets réveillés en sommeil paradoxal ont répondu avec des associations atypiques, ce qui suggère que le sommeil paradoxal est spécifique dans sa capacité à intégrer les traces de la mémoire émotionnelle (article 1). En outre, les rapports de rêve en sommeil paradoxal étaient plus bizarres que ceux en sommeil lent, et plus intenses émotionnellement ; ces attributs semblent refléter la nature associative et émotionnelle du sommeil paradoxal (article 2). Le deuxième objectif de la thèse était de préciser si et comment le traitement de la mémoire émotionnelle en sommeil paradoxal est altéré dans le Trouble de cauchemars fréquents (NM). En utilisant le même protocole, nos résultats ont montré que les participants NM avaient des résultats plus élevés avant une sieste, ce qui correspond aux observations antérieures voulant que les personnes souffrant de cauchemars soient plus créatives. Après le sommeil paradoxal, les deux groupes, NM et CTL, ont montré des changements similaires dans leur accès associatif, avec des résultats AB-négatif plus bas et AB-positif plus grands. Une semaine plus tard, seul les participants NM a maintenu ce changement dans leur réseau sémantique (article 3). Ces résultats suggèrent qu’au fil du temps, les cauchemars peuvent interférer avec l'intégration de la mémoire émotionnelle pendant le sommeil paradoxal. En ce qui concerne l'imagerie, les participants NM avaient plus de bizarrerie et plus d’émotion positive, mais pas négative, dans leurs rêveries (article 4). Ces attributs intensifiés suggèrent à nouveau que les participants NM sont plus imaginatifs et créatifs à l’éveil. Dans l'ensemble, les résultats confirment le rôle du sommeil paradoxal dans l'intégration associative de la mémoire émotionnelle. Cependant, nos résultats concernant le Trouble de cauchemars ne sont pas entièrement en accord avec les théories suggérant que les cauchemars sont dysfonctionnels. Le groupe NM a montré plus d’associativité émotionnelle, de même que plus d'imagerie positive et bizarre à l’éveil. Nous proposons donc une nouvelle théorie de sensibilité environnementale associée au Trouble de cauchemar, suggérant qu'une sensibilité accrue à une gamme de contextes environnementaux sous-tendrait les symptômes uniques et la richesse imaginative observés chez les personnes souffrant de cauchemars fréquents. Bien que davantage de recherches doivent être faites, il est possible que ces personnes puissent bénéficier e milieux favorables, et qu’elles puissent avoir un avantage adaptatif à l'égard de l'expression créative, ce qui est particulièrement pertinent lorsque l'on considère leur pronostic et les différents types de traitements. / Existing literature suggests that REM sleep plays a role in the associative integration of emotional memory, and that attributes of dreams during REM sleep, particularly their bizarre and emotional nature, either reflect or even influence this associative and emotional function. The consequence of frequent nightmares on this process is unknown, although, the experience of a nightmare suggests an associative restriction imposed by intense negative emotion, consistent with research showing that negative affect tends to restrict cognitive flexibility in wake. This is consistent with existing theories of nightmare function, largely purporting that nightmares reflect temporary failures in emotion regulation. The first objective of the thesis was to conceptually replicate prior research portraying REM sleep as enabling increased associative access to emotional memory. The use of a daytime nap allowed us to assess the effects of REM sleep, compared to both NREM sleep and waking, on participant performance on a novel task measuring Associational Breadth (AB). Results showed that only those subjects awakened from REM sleep responded with atypical emotional word associations, suggesting that REM is specific in its capacity to broadly integrate emotional memory traces (article 1). Further, REM dream reports were more bizarre than both NREM dreams and waking daydreams, and more emotionally intense than NREM dreams; these attributes are thought to reflect the hyper-associative and emotional nature of REM sleep (article 2). The second objective was to clarify whether and how REM sleep-dependent emotional memory processing is altered in frequent nightmares sufferers. Using a similar nap protocol, our results showed that NM participants had higher baseline AB in response to emotional cue-words, contrary to predictions, but nonetheless corresponding with anecdotal reports of heightened creativity. Following REM sleep, both NM and CTL groups showed similar changes in associative access to emotional cue-words, with negative AB being restricted and positive AB being broadened; one week later, the NM group alone maintained this altered pattern of emotional semantic access (article 3). This finding suggests that, over time, nightmares may interfere with REM sleep-dependent emotional memory integration. Regarding imagery, the NM participants had heightened bizarreness, and positive, but not negative, imagery in their daydreams, but not their dreams (article 4), mirroring our AB finding that the NM group had significantly higher emotional associativity in wake, although patterns of associativity following a REM sleep nap did not differ between groups. Overall, findings support a role of REM sleep in the associative integration of emotional memory. However, our findings regarding nightmare sufferers are not entirely consistent with views that nightmares are associated with dysfunctional emotional memory processing. Although they did show a prolonged priming effect suggestive of inadequate emotion regulation, they also showed heightened semantic associativity and vivid positive imagery in wake. We therefore propose a novel Environmental Sensitivity framework for the study of nightmare sufferers, claiming that an increased sensitivity to a range of environmental contexts, not only negative contexts, underlies the unique symptoms and imaginative richness seen in frequent nightmare sufferers. Although further empirical research exploring potentially adaptive traits or sensitivity to positive contexts in nightmare sufferers is needed, the possibility that these individuals may benefit especially from supportive environments, and may have heightened creativity and semantic associativity, is particularly relevant when considering prognosis and treatment approaches.
52

Fuzzy neuronové sítě / Fuzzy Neural Networks

González, Marek January 2015 (has links)
This thesis focuses on fuzzy neural networks. The combination of the fuzzy logic and artificial neural networks leads to the development of more robust systems. These systems are used in various field of the research, such as artificial intelligence, machine learning and control theory. First, we provide a quick overview of underlying neural networks and fuzzy systems to explain fundamental ideas that form the basis of the fields, and follow with the introduction of the fuzzy neural network theory, classification and application. Then we describe a design and a realization of the fuzzy associative memory, as an example of these systems. Finally, we benchmark the realization using the pattern recognition and control tasks. The results are evaluated and compared against existing systems.
53

Modelos de memória associativa em redes neurais para planejamento e controle ponto a ponto de trajetória para um braço mecânico / Associative memory models in neural networks for point to point control and planning robot arm trajectory

Vieira, Marcelo 12 December 1997 (has links)
A contribuição e objetivo desta tese é desenvolver um modelo de redes neurais artificiais, baseado em princípios de memória associativa, capaz de resolver o problema de planejamento e controle ponto a ponto de trajetória de um braço mecânico imerso em um ambiente parcialmente conhecido e/ou sujeito a ruídos. O modelo proposto é formado por dois planos: plano seqüência temporal e plano ângulo. Para o plano seqüência temporal, o novo modelo proposto chamado de Memória Associativa Multidirecional Temporal (TMAM) é capaz de armazenar e recuperar n-tuplas de informações, lidar com informações ruidosas e/ou incompletas e aprender seqüências temporais. TMAM utiliza representação contínua e realimentação autoassociativa. O plano ângulo é formado pelo modelo RBF que é responsável por produzir as informações de ângulos das juntas do braço mecânico. A composição dos dois planos forma o sistema completo que é responsável pelo planejamento e controle ponto a ponto de trajetória. Em resumo, o sistema recebe informações do ponto origem e do ponto alvo, estabelece uma trajetória para atingir o ponto alvo a partir do ponto de origem e transforma os pontos espaciais da trajetória em valores de ângulos das juntas. Os resultados obtidos mostram que o modelo TMAM é capaz de recuperar, interpelar e extrapolar pontos nas seqüências, é capaz de gerar trajetórias, de memorizar seqüências de diferentes tamanhos e de lidar com duas trajetórias ao mesmo tempo. O modelo apresenta também rápido treinamento. O modelo RBF é capaz de recuperar as saídas desejadas apresentando um erro pequeno e é capaz de receber um padrão que apresenta um ponto final inatingível e gerar um conjunto de ângulos que representa um ponto final atingível. / The aim of this project is to develop an artificial neural networks model based on principles of associative memory. This neural network model must be able to solve the problem of trajectory planning and point to point control of a robot arm, which is located in a partially known and/or noisy environment. The proposed model is composed by two surfaces: the temporal sequence surface and the angle surface. For the temporal sequence surface the new propose model Temporal Multidirectional Associative Memmy (TMAM) is able to store and recall n-tuplas of information, to deal with noisy and/or incomplete information and to learn temporal sequences. TMAM uses a continuas representation and autoassociative feedback. A RBF model is used to implement the angle surface, which is liable for producing the angle information for the joint of the robot arm. The two surfaces compose the whole system which is liable for the trajectory planning and system control. Hence, the system receives information about the initial point and the target point, constructs the trajectory to reach the target point from the initial point and converts the spatial points which compose the trajectory, in values of joint angles. The obtained results show that TMAM model can recall, interpolate and extrapolate points in the sequences. The model has the ability of generating new trajectories and memorizing different size of sequences at the same time. This model also shows fast learning. The RBF model can recall the desired outputs with a small error and can receive a pattern which is formed by an unreachable final point and generate a set of angles which, in turn, represent a reachable final point.
54

Impact of N-terminally truncated Aß4-42 on memory and synaptic plasticity - Tg4-42 a new mouse model of Alzheimer's disease

Dietrich, Katharina 17 December 2014 (has links)
No description available.
55

Modelos de memória associativa em redes neurais para planejamento e controle ponto a ponto de trajetória para um braço mecânico / Associative memory models in neural networks for point to point control and planning robot arm trajectory

Marcelo Vieira 12 December 1997 (has links)
A contribuição e objetivo desta tese é desenvolver um modelo de redes neurais artificiais, baseado em princípios de memória associativa, capaz de resolver o problema de planejamento e controle ponto a ponto de trajetória de um braço mecânico imerso em um ambiente parcialmente conhecido e/ou sujeito a ruídos. O modelo proposto é formado por dois planos: plano seqüência temporal e plano ângulo. Para o plano seqüência temporal, o novo modelo proposto chamado de Memória Associativa Multidirecional Temporal (TMAM) é capaz de armazenar e recuperar n-tuplas de informações, lidar com informações ruidosas e/ou incompletas e aprender seqüências temporais. TMAM utiliza representação contínua e realimentação autoassociativa. O plano ângulo é formado pelo modelo RBF que é responsável por produzir as informações de ângulos das juntas do braço mecânico. A composição dos dois planos forma o sistema completo que é responsável pelo planejamento e controle ponto a ponto de trajetória. Em resumo, o sistema recebe informações do ponto origem e do ponto alvo, estabelece uma trajetória para atingir o ponto alvo a partir do ponto de origem e transforma os pontos espaciais da trajetória em valores de ângulos das juntas. Os resultados obtidos mostram que o modelo TMAM é capaz de recuperar, interpelar e extrapolar pontos nas seqüências, é capaz de gerar trajetórias, de memorizar seqüências de diferentes tamanhos e de lidar com duas trajetórias ao mesmo tempo. O modelo apresenta também rápido treinamento. O modelo RBF é capaz de recuperar as saídas desejadas apresentando um erro pequeno e é capaz de receber um padrão que apresenta um ponto final inatingível e gerar um conjunto de ângulos que representa um ponto final atingível. / The aim of this project is to develop an artificial neural networks model based on principles of associative memory. This neural network model must be able to solve the problem of trajectory planning and point to point control of a robot arm, which is located in a partially known and/or noisy environment. The proposed model is composed by two surfaces: the temporal sequence surface and the angle surface. For the temporal sequence surface the new propose model Temporal Multidirectional Associative Memmy (TMAM) is able to store and recall n-tuplas of information, to deal with noisy and/or incomplete information and to learn temporal sequences. TMAM uses a continuas representation and autoassociative feedback. A RBF model is used to implement the angle surface, which is liable for producing the angle information for the joint of the robot arm. The two surfaces compose the whole system which is liable for the trajectory planning and system control. Hence, the system receives information about the initial point and the target point, constructs the trajectory to reach the target point from the initial point and converts the spatial points which compose the trajectory, in values of joint angles. The obtained results show that TMAM model can recall, interpolate and extrapolate points in the sequences. The model has the ability of generating new trajectories and memorizing different size of sequences at the same time. This model also shows fast learning. The RBF model can recall the desired outputs with a small error and can receive a pattern which is formed by an unreachable final point and generate a set of angles which, in turn, represent a reachable final point.
56

Translational potential of the touchscreen-based methodology to assess cognitive abilities in mice / Potentiel translationnel d'une méthodologie basée sur des écrans tactiles pour évaluer les capacités cognitives chez la souris

Delotterie, David 24 September 2014 (has links)
Ce travail visait à évaluer le potentiel d’une méthodologie innovante récemment adaptée à la Souris sur la base de tests neuropsychologiques utilisés en clinique humaine. Après optimisation de 3 tâches (PAL, VMCL, PVD) ciblant différentes fonctions cognitives chez l’animal, nos études ont établi : (1) l’existence possible d’interférences proactives lors d’apprentissages consécutifs ; (2) l’absence de déficit d’acquisition chez les souris de la lignée Tg2576 (modèle transgénique de la maladie d’Alzheimer), quelle que soit l’étendue de la charge amyloïde ; (3) l’implication spécifique du striatum dorsal lors de l’acquisition des tâches de VMCL et PAL, et celle de l’hippocampe lors du rappel de cette dernière tâche. Ces derniers résultats suggèrent qu’en dépit des efforts déployés pour s’assurer du caractère translationnel d’une tâche cognitive dans le paradigme du touchscreen, certaines adaptations inhérentes à chaque espèce influencent profondément les bases neurobiologiques associées. / This thesis work aimed to specify the potential of an innovative methodology latterly adapted in mice from neuropsychological tasks used in Humans. After the optimization of 3 assays (PAL, VMCL, PVD) taxing various cognitive functions in animals, different behavioral studies have gradually revealed: (1) the putative existence of proactive interferences over consecutive learnings in touchscreen tasks; (2) no acquisition deficit in Tg2576 mice (a transgenic model of Alzheimer’s Disease) in these paradigms, whatever the amyloid load considered; (3) the specific involvement of the dorsal striatum during the acquisition of VMCL and PAL tasks and the key role of the hippocampus during the recall of the latter task. As exemplified by the PAL task, our results suggest that despite momentous efforts in order to ensure the translational feature of touchscreen cognitive tasks, certain adaptations inherent to each species deeply influence the nature of underlying neurobiological substrates.
57

Implication fonctionnelle des récepteurs NMDA corticaux au cours des processus de consolidation systémique et d’oubli de la mémoire associative chez le rat / Functional dynamics of cortical NMDA receptors during systems-level memory consolidation and forgetting

Bessieres, Benjamin 31 March 2016 (has links)
Initialement encodés dans l’hippocampe, les nouveaux souvenirs déclaratifs deviennent progressivement dépendants d’un réseau distribué de neurones corticaux au cours de leur maturation dans le temps. Cependant, les mécanismes cellulaires et moléculaires sous-­‐tendant la consolidation et le stockage à long terme de ces nouveaux souvenirs au sein des réseaux corticaux restent à élucider. Les récepteurs N-­‐méthyl-­‐D-­‐aspartate (RNMDA) jouent un rôle essentiel dans l’induction et la régulation des changements synaptiques sous-­‐tendant les processus mnésiques de type associatifs. Sur la base de leurs propriétés biophysiques respectives, nous avons formulé l’hypothèse que la redistribution synaptique des deux formes principales de sous-­‐unités GluN2 exprimées dans le néocortex adulte (GluN2A and GluN2B), pourrait constituer un mécanisme de régulation de la plasticité synaptique supportant l’intégration et la stabilisation progressive des souvenirs au niveau cortical au cours du processus de consolidation mnésique. En combinant, chez le rat adulte, une approche comportementale, biochimique, pharmacologique et des stratégies innovantes consistant à manipuler le trafic de sous-­‐unités des RNMDA à la surface synaptique, nos résultats mettent en évidence un changement cortical dans la composition synaptique en sous unités GluN2, lequel régule la stabilisation progressive de la mémoire à long terme au sein des réseaux corticaux. Nous avons d'abord établi que les RNMDA contenant la sous-­‐unité GluN2B, via leur interaction spécifique avec une protéine clé de la signalisation synaptique, la CaMKII, sont préférentiellement recrutés lors de la phase d’encodage pour permettre l’allocation des nouveaux souvenirs olfactifs associatifs dans un réseau de neurones corticaux spécifique. Au cours du processus de consolidation, nous avons révélé que la redistribution des RNMDA corticaux contenant les sous-­‐unités GluN2B vers l’extérieur ou l’intérieur de l’espace synaptique suite à l’apprentissage, contrôle respectivement la stabilisation de la mémoire à long terme et son oubli au cours du temps. Enfin, renforcer l’acquisition initiale conduit à une augmentation plus rapide du ratio post-­‐synaptique GluN2A/GluN2B et accélère la cinétique du dialogue hippocampo-­‐cortical, ce qui se traduit par une stabilisation accélérée des souvenirs au sein des réseaux corticaux. Pris dans leur ensemble, nos travaux montrent que le trafic des GluN2B-­‐RNMDA corticaux représente un mécanisme cellulaire majeur conditionnant le devenir des traces mnésiques (i.e. stabilisation versus oubli) et apporte un éclairage nouveau sur la façon dont le cerveau organise les souvenirs récents et anciens. / Initially encoded in the hippocampus, new declarative memories are thought to become progressively dependent on a broadly distributed cortical network as they mature and consolidate over time. Although we have a good understanding of the mechanisms underlying the formation of new memories in the hippocampus, little is known about the cellular and molecular mechanisms by which recently acquired information is transformed into remote memories at the cortical level. The N-­‐methyl-­‐D-­‐aspartate receptor (NMDAR) is widely known to be a key player in many aspects of long-­‐term experience-­‐dependent synaptic changes underlying associative memory processes. Based on their distinct biophysical properties, we postulated that the activity-­‐dependent surface dynamics of the two predominant GluN2 subunits (GluN2A and GluN2B) of NMDARs present in the adult neocortex could provide a metaplastic control of synaptic plasticity supporting the progressive embedding and stabilization of long-­‐lasting associative memories within cortical networks during memory consolidation. By combining, in adult rats, behavioral, biochemical, pharmacological and innovative strategies consisting in manipulating trafficking of NMDAR subunits at the cell membrane, our results identify a cortical switch in the synaptic GluN2-­‐containing NMDAR composition which drives the progressive embedding and stabilization of long-­‐lasting memories within cortical networks. We first established that cortical GluN2B-­‐containing NMDARs and their specific interactions with the synaptic signaling CaMKII protein are preferentially recruited upon encoding of associative olfactory memories to enable neuronal allocation, the process via which a new memory trace is thought to be allocated to a given neuronal network. As these memories are progressively processed and embedded into cortical networks, we observed a learning-­‐induced surface redistribution of cortical GluN2B-­‐containing NMDARs outwards or inwards synapses which respectively drives the progressive stabilization and subsequent forgetting of remote memories over time. Finally, increasing the strength, upon encoding, of the initial memory leads to a faster increase of the cortical GluN2A/GluN2B synaptic ratio and accelerates the kinetics of hippocampal-­‐cortical interactions, which translated into a faster stabilization of memories within cortical networks. Taken together, our results provide evidence that GluN2B-­‐NMDAR surface trafficking controls the fate of remote memories (i.e. stabilization versus forgetting), shedding light on a novel mechanism used by the brain to organize recent and remote memories.
58

Evaluation automatique des états émotionnels et dépressifs : vers un système de prévention des risques psychosociaux / Automatic evaluation of emotional and depressive states : towards a prevention system for psychosocial risks

Cholet, Stéphane 17 June 2019 (has links)
Les risques psychosociaux sont un enjeu de santé publique majeur, en particulier à cause des troubles qu'ils peuvent engendrer : stress, changements d'humeurs, burn-out, etc. Bien que le diagnostic de ces troubles doive être réalisé par un professionel, l'Affective Computing peut apporter une contribution en améliorant la compréhension des phénomènes. L'Affective Computing (ou Informatique Affective) est un domaine pluridisciplinaire, faisant intervenir des concepts d'Intelligence Artificielle, de psychologie et de psychiatrie, notamment. Dans ce travail de recherche, on s'intéresse à deux éléments pouvant faire l'objet de troubles : l'état émotionnel et l'état dépressif des individus.Le concept d'émotion couvre un très large champ de définitions et de modélisations, pour la plupart issues de travaux en psychiatrie ou en psychologie. C'est le cas, par exemple, du circumplex de Russell, qui définit une émotion comme étant la combinaison de deux dimensions affectives, nommées valence et arousal. La valence dénote le caractère triste ou joyeux d'un individu, alors que l'arousal qualifie son caractère passif ou actif. L'évaluation automatique des états émotionnels a suscité, dans la dernière décénie, un regain d'intérêt notable. Des méthodes issues de l'Intelligence Artificielle permettent d'atteindre des performances intéressantes, à partir de données capturées de manière non-invasive, comme des vidéos. Cependant, il demeure un aspect peu étudié : celui des intensités émotionnelles, et de la possibilité de les reconnaître. Dans cette thèse, nous avons exploré cet aspect au moyen de méthodes de visualisation et de classification pour montrer que l'usage de classes d'intensités émotionnelles, plutôt que de valeurs continues, bénéficie à la fois à la reconnaissance automatique et à l'interprétation des états.Le concept de dépression connaît un cadre plus strict, dans la mesure où c'est une maladie reconnue en tant que telle. Elle atteint les individus sans distinction d'âge, de genre ou de métier, mais varie en intensité ou en nature des symptômes. Pour cette raison, son étude tant au niveau de la détection que du suivi, présente un intérêt majeur pour la prévention des risques psychosociaux.Toutefois, son diagnostic est rendu difficile par le caractère parfois anodin des symptômes et par la démarche souvent délicate de consulter un spécialiste. L'échelle de Beck et le score associé permettent, au moyen d'un questionnaire, d'évaluer la sévérité de l'état dépressif d'un individu. Le système que nous avons développé est capable de reconnaître automatiquement le score dépressif d'un individu à partir de vidéos. Il comprend, d'une part, un descripteur visuel spatio-temporel bas niveau qui quantifie les micro et les macro-mouvements faciaux et, d'autre part, des méthodes neuronales issues des sciences cognitives. Sa rapidité autorise des applications de reconnaissance des états dépressifs en temps réel, et ses performances sont intéressantes au regard de l'état de l'art. La fusion des modalités visuelles et auditives a également fait l'objet d'une étude, qui montre que l'utilisation de ces deux canaux sensoriels bénéficie à la reconnaissance des états dépressifs.Au-delà des performances et de son originalité, l'un des points forts de ce travail de thèse est l'interprétabilité des méthodes. En effet, dans un contexte pluridisciplinaire tel que celui posé par l'Affective Computing, l'amélioration des connaissances et la compréhension des phénomènes étudiés sont des aspects majeurs que les méthodes informatiques sous forme de "boîte noire" ont souvent du mal à appréhender. / Psychosocial risks are a major public health issue, because of the disorders they can trigger : stress, mood swings, burn-outs, etc. Although propoer diagnosis can only be made by a healthcare professionnel, Affective Computing can make a contribution by improving the understanding of the phenomena. Affective Computing is a multidisciplinary field involving concepts of Artificial Intelligence, psychology and psychiatry, among others. In this research, we are interested in two elements that can be subject to disorders: the emotional state and the depressive state of individuals.The concept of emotion covers a wide range of definitions and models, most of which are based on work in psychiatry or psychology. A famous example is Russell's circumplex, which defines an emotion as the combination of two emotional dimensions, called valence and arousal. Valence denotes an individual's sad or joyful character, while arousal denotes his passive or active character. The automatic evaluation of emotional states has generated a significant revival of interest in the last decade. Methods from Artificial Intelligence allow to achieve interesting performances, from data captured in a non-invasive manner, such as videos. However, there is one aspect that has not been studied much: that of emotional intensities and the possibility of recognizing them. In this thesis, we have explored this aspect using visualization and classification methods to show that the use of emotional intensity classes, rather than continuous values, benefits both automatic recognition and state interpretation.The concept of depression is more strict, as it is a recognized disease as such. It affects individuals regardless of age, gender or occupation, but varies in intensity or nature of symptoms. For this reason, its study, both at the level of detection and monitoring, is of major interest for the prevention of psychosocial risks.However, his diagnosis is made difficult by the sometimes innocuous nature of the symptoms and by the often delicate process of consulting a specialist. The Beck's scale and the associated score allow, by means of a questionnaire, to evaluate the severity of an individual's state of depression. The system we have developed is able to automatically recognize an individual's depressive score from videos. It includes, on the one hand, a low-level visual spatio-temporal descriptor that quantifies micro and macro facial movements and, on the other hand, neural methods from the cognitive sciences. Its speed allows applications for real-time recognition of depressive states, and its performance is interesting with regard to the state of the art. The fusion of visual and auditory modalities has also been studied, showing that the use of these two sensory channels benefits the recognition of depressive states.Beyond performance and originality, one of the strong points of this thesis is the interpretability of the methods. Indeed, in a multidisciplinary context such as that of Affective Computing, improving knowledge and understanding of the studied phenomena is a key point that usual computer methods implemeted as "black boxes" can't deal with.
59

Αρχιτεκτονικές επεξεργαστών και μνημών ειδικού σκοπού για την υποστήριξη φερέγγυων (ασφαλών) δικτυακών υπηρεσιών / Processor and memory architectures for trusted computing platforms

Κεραμίδας, Γεώργιος 27 October 2008 (has links)
Η ασφάλεια των υπολογιστικών συστημάτων αποτελεί πλέον μια πολύ ενεργή περιοχή και αναμένεται να γίνει μια νέα παράμετρος σχεδίασης ισάξια μάλιστα με τις κλασσικές παραμέτρους σχεδίασης των συστημάτων, όπως είναι η απόδοση, η κατανάλωση ισχύος και το κόστος. Οι φερέγγυες υπολογιστικές πλατφόρμες έχουν προταθεί σαν μια υποσχόμενη λύση, ώστε να αυξήσουν τα επίπεδα ασφάλειας των συστημάτων και να παρέχουν προστασία από μη εξουσιοδοτημένη άδεια χρήσης των πληροφοριών που είναι αποθηκευμένες σε ένα σύστημα. Ένα φερέγγυο σύστημα θα πρέπει να διαθέτει τους κατάλληλους μηχανισμούς, ώστε να είναι ικανό να αντιστέκεται στο σύνολο, τόσο γνωστών όσο και νέων, επιθέσεων άρνησης υπηρεσίας. Οι επιθέσεις αυτές μπορεί να έχουν ως στόχο να βλάψουν το υλικό ή/και το λογισμικό του συστήματος. Ωστόσο, η μεγαλύτερη βαρύτητα στην περιοχή έχει δοθεί στην αποτροπή επιθέσεων σε επίπεδο λογισμικού. Στην παρούσα διατριβή προτείνονται έξι μεθοδολογίες σχεδίασης ικανές να θωρακίσουν ένα υπολογιστικό σύστημα από επιθέσεις άρνησης υπηρεσίας που έχουν ως στόχο να πλήξουν το υλικό του συστήματος. Η κύρια έμφαση δίνεται στο υποσύστημα της μνήμης (κρυφές μνήμες). Στις κρυφές μνήμες αφιερώνεται ένα μεγάλο μέρος της επιφάνειας του ολοκληρωμένου, είναι αυτές που καλούνται να "αποκρύψουν" τους αργούς χρόνους απόκρισης της κύριας μνήμης και ταυτόχρονα σε αυτές οφείλεται ένα μεγάλο μέρος της συνολικής κατανάλωσης ισχύος. Ως εκ τούτου, παρέχοντας βελτιστοποιήσεις στις κρυφές μνήμες καταφέρνουμε τελικά να μειώσουμε τον χρόνο εκτέλεσης του λογισμικού, να αυξήσουμε το ρυθμό μετάδοσης των ψηφιακών δεδομένων και να θωρακίσουμε το σύστημα από επιθέσεις άρνησης υπηρεσίας σε επίπεδο υλικού. / Data security concerns have recently become very important, and it can be expected that security will join performance, power and cost as a key distinguish factor in computer systems. Trusted platforms have been proposed as a promising approach to enhance the security of the modern computer system and prevent unauthorized accesses and modifications of the sensitive information stored in the system. Unfortunately, previous approaches only provide a level of security against software-based attacks and leave the system wide open to hardware attacks. This dissertation thesis proposes six design methodologies to shield a uniprocessor or a multiprocessor system against a various number of Denial of Service (DoS) attacks at the architectural and the operating system level. Specific focus is given to the memory subsystem (i.e. cache memories). The cache memories account for a large portion of the silicon area, they are greedy power consumers and they seriously determine system performance due to the even growing gap between the processor speed and main memory access latency. As a result, in this thesis we propose methodologies to optimize the functionality and lower the power consumption of the cache memories. The goal in all cases is to increase the performance of the system, the achieved packet throughput and to enhance the protection against a various number of passive and Denial of Service attacks.
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Behavioural and Structural Adaptation to Hippocampal Dysfunction in Humans

Pajkert, Anna Ewa 02 September 2020 (has links)
Die flexible Anwendung von Wissen in neuen Alltagssituationen ist eine notwendige kognitive Fähigkeit. Bisherige Studien betonen die zentrale Rolle des Hippocampus beim Lernen und Verknüpfen neuer Informationen mit bereits vorhandenem Wissen. Die funktionelle Integrität des Hippocampus ändert sich jedoch im Laufe des Lebens bzw. wird durch neuropsychiatrische Erkrankungen häufig beeinflusst. Die betroffenen Personen müssen deswegen adaptive Strategien entwickeln, um behaviorale Ziele weiter zu erreichen. Daher befasst sich meine Doktorarbeit mit Adaptationsprozessen im sich entwickelnden Gehirn und im vollständig entwickelten Gehirn mit einer hippocampalen Dysfunktion. Diese Synopsis umfasst dazu drei Studien: (1) zu behavioralen Strategien im sich entwickelnden Gehirn, (2) zu behavioralen Strategien im vollständig entwickelten Gehirn nach einer Läsion und (3) zu strukturellen Veränderungen im vollständig entwickelten Gehirn nach einer Läsion. Studie 1 zeigt einen altersgebundenen Wechsel beim assoziativen Gedächtnis: Kinder, Jugendliche und junge Erwachsene benutzen verschiedene Gedächtnisstrategien beim Integrieren von Gedächtnisinhalten. Studie 2 zeigt, dass die beobachteten Gedächtnisbeeinträchtigungen bei Patienten mit rechtsseitigen hippocampalen Läsionen sich nicht alleine durch ein Defizit des assoziativen Gedächtnisses erklären lassen, sondern auf einen zusätzlichen hippocampalen Beitrag zur Gedächtnisintegration zurückzuführen sind. Studie 3 zeigt, dass sich postoperative Adaptationsprozesse auf struktureller Ebene in überraschend kurzer Zeit ereignen und dass die strukturelle Reorganisation nicht nur im Hippocampus, sondern auch in entfernteren Hirnregionen, die mit dem Hippocampus verbunden sind, stattfindet. Zusammenfassend zeigen die Ergebnisse der drei Studien, dass Adaptationsprozesse im sich entwickelnden Gehirn sowie bei Erwachsenen mit einer hippocampalen Dysfunktion sowohl auf der behavioralen als auch auf der strukturellen Ebene auftreten. / Applying knowledge flexibly to new situations is a cognitive faculty that is necessary in every-day life. Previous findings emphasise the crucial role the hippocampus plays in learning and linking new information with pre-existing knowledge. However, the functional integrity of the hippocampus changes over the lifespan and is frequently affected by neuropsychiatric disorders. The affected subjects must, therefore, develop adaptive strategies to achieve behavioural goals. Thus, my doctoral thesis deals with adaptation processes in the developing brain and in adult brains with a hippocampal dysfunction. This synopsis encompasses three studies on: (1) behavioural strategies in the developing brain, (2) behavioural strategies in the lesioned fully developed brain, and (3) structural changes in the lesioned fully developed brain. Study 1 suggests an age-related shift in the associative memory: Children, adolescents, and young adults use different memory strategies when integrating information. Study 2 suggests that the memory deficits observed in patients with right-sided hippocampal lesions are not merely a consequence of an impaired associative memory but rather result from an additional hippocampal contribution to the memory integration. Study 3 suggests that postoperative structural adaptation processes occur on a surprisingly short time-scale, and this structural reorganisation happens not only in the hippocampus but also in distant brain areas connected to the hippocampus. In conclusion, findings from these three studies show that adaptation processes in the developing brain and in adult brains with hippocampal dysfunction occur on both the behavioural and the structural level.

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