Le module de l'apprenant est l'une des composantes les plus importantes d’un Système Tutoriel Intelligent (STI). L'extension du modèle de l'apprenant n'a pas cessé de progresser. Malgré la définition d’un profil cognitif et l’intégration d’un profil émotionnel, le module de l’apprenant demeure non exhaustif. Plusieurs senseurs physiologiques sont utilisés pour raffiner la reconnaissance des états cognitif et émotionnel de l’apprenant mais l’emploi simultané de tous ces senseurs l’encombre. De plus, ils ne sont pas toujours adaptés aux apprenants dont les capacités sont réduites. Par ailleurs, la plupart des stratégies pédagogiques exécutées par le module du tuteur ne sont pas conçues à la base d’une collecte dynamique de données en temps réel, cela diminue donc de leur efficacité. L’objectif de notre recherche est d’explorer l’activité électrique cérébrale et de l’utiliser comme un nouveau canal de communication entre le STI et l’apprenant. Pour ce faire nous proposons de concevoir, d’implémenter et d’évaluer le système multi agents NORA. Grâce aux agents de NORA, il est possible d’interpréter et d’influencer l’activité électrique cérébrale de l’apprenant pour un meilleur apprentissage. Ainsi, NORA enrichit le module apprenant d’un profile cérébral et le module tuteur de quelques nouvelles stratégies neuropédagogiques efficaces. L’intégration de NORA à un STI donne naissance à une nouvelle génération de systèmes tutoriels : les STI Cérébro-sensibles (ou STICS) destinés à aider un plus grand nombre d’apprenants à interagir avec l’ordinateur pour apprendre à gérer leurs émotions, maintenir la concentration et maximiser les conditions favorable à l’apprentissage. / The learner module is the most important component within an Intelligent Tutoring System (ITS). The extension of the learner module is still in progress, despite the integration of the cognitive profile and the emotional profile, it is not yet exhaustive. To improve the prediction of the learner’s emotional and cognitive states, many physiological sensors have been used, but all of these sensors are cumbersome. In addition, they are not always adapted to the learners with reduced capacities. Beside, most of the pedagogical strategies that are executed by the tutor module are based on no-live collections of data. This fact reduces their efficiency. The objective of our research is to explore the electrical brain activity and use it as a communication channel between a learner and an ITS. To reach this aim, we suggest to conceive, to implement and to evaluate the multi-agent system NORA. Integrated to an ITS, this one became a Brain Sensitive Intelligent Tutoring System (BS-ITS). Agents of NORA interpret the learner’s brain electrical signal and react to it. The new BS-ITS is the extension of an ITS and enrich the learner module with the brain profile and the tutor module with a new Neuropedagogical Strategies. We aim to reach more categories of learners and help them to manage their stress, anxiety and maintain the concentration, the attention and the interest.

Il existe peu d’études sur les effets physiologiques et pharmacologiques du médicament anesthésiant le plus utilisé chez les anoures, la tricaïne méthanesulfonate, et son utilisation chez la grenouille Xenopus laevis. Notre premier objectif était d’évaluer l’effet de bains d’immersion de 20 minutes de 1 et 2 g/L de tricaïne méthanesulfonate sur la fonction cardiorespiratoire, l’analgésie et les réflexes ainsi que d’étudier la pharmacocinétique. Nos résultats démontrent que des bains de 1 et 2 g/L produisent une anesthésie chirurgicale de 30 et 60 minutes respectivement, sans effet significatif sur le système cardiorespiratoire. À la suite d’une immersion à 2 g/L, on note une demi-vie terminale de 3,9 heures. Cette dose ne produit aucun effet sur l’histologie des tissus 24 heures après l’immersion. Dans une deuxième expérience, nous avons évalué les effets d’une surdose de tricaïne méthanesulfonate en bain d’immersion sur les systèmes cardiorespiratoire et nerveux central grâce à l’électroencéphalographie ainsi que l’effet d’une injection de pentobarbital sodique après 2 heures d’immersion. L’EEG montre un effet dépresseur sur le SNC avec l’utilisation de la tricaïne méthanesulfonate sans voir un arrêt de signal d’EEG sur la période de 2 heures d’enregistrement. Les surdoses à 1 g/L et 3 g/L n’ont pas d’effet significatif sur le rythme cardiaque, et l’injection de pentobarbital suite au bain d’immersion de tricaïne méthanesulfonate est nécessaire pour induire l’euthanasie. Nous avons démontré que le bain de tricaïne méthanesulfonate peut produire une anesthésie de 30 à 60 minutes avec dépression du SNC sans effet cardiovasculaire chez les Xenopus laevis. / Very few studies exist on the physiological and pharmacological effects of the most commonly used anesthetic agent used in amphibians, tricaine methanesulfonate, in Xenopus laevis frogs. Our first goal was to measure the effects of 20 minutes bath immersions of 1 and 2 g/L tricaine methanesulfonate on cardiorespiratory system, analgesia and reflexes. We also studied the pharmacokinetic of tricaine methanesulfonate following an immersion in a 2 g/L bath. Our results show that both 1 and 2 g/L baths produce surgical anesthesia during 30 and 60 minutes respectively, without significant effect on the cardiorespiratory system. Following the immersion in a 2 g/L bath, the tricaine methanesulfonate has a terminal half-life of 3,9 hours and no effect on tissue histology is observed 24 hours after anesthesia. In a second experiment, we evaluated the effects of tricaine methanesulfonate overdose on cardiorespiratory system and on central nervous system using electroencephalography. Moreover, we evaluated the effect of sodium pentobarbital injection after 2 hours of immersion. A significant EEG depression of central nervous system activity occurred with the use of tricaine methanesulfonate following 2 hours of recording and the pentobarbital injection was necessary to induce euthanasia. We showed that tricaine methanesulfonate can produce safe anesthesia of 30 to 60 minutes with reduction of CNS activity and without cardiorespiratory effect in Xenopus laevis.

Understanding speech in the presence of noise can be difficult, especially when suffering from a hearing loss. This thesis examined behavioural and electrophysiological measures of speech processing with the aim of establishing how they were influenced by hearing loss (internal degradation) and listening condition (external degradation). The hypothesis that more internal and external degradation of a speech signal would result in higher working memory (WM) involvement was investigated in four studies. The behavioural measure of speech recognition consistently decreased with worse hearing, whereas lower WM capacity only resulted in poorer speech recognition when sound were spatially co-located. Electrophysiological data (EEG) recorded during speech processing, revealed that worse hearing was associated with an increase in inhibitory alpha activity (~10 Hz). This indicates that listeners with worse hearing experienced a higher degree of WM involvement during the listening task. When increasing the level of background noise, listeners with poorer hearing exhibited a breakdown in alpha activity, suggesting that these listeners reached a ceiling at which no more WM resources could be released through neural inhibition. Worse hearing was also associated with a reduced ability to selectively attend to one of two simultaneous talkers, brought on by a reduced neural inhibition of the to-be-ignored speech. Increasing the level of background noise reduced the ability to neurally track the to-be-attended speech. That internal and external degradation affected the tracking of ignored and attended speech, respectively, indicates that the two speech streams were neurally processed as independent objects. This thesis demonstrates for the first time that hearing loss causes changes in the induced neural activity during speech processing. In the last paper of the thesis, it is tentatively suggested that neural activity can be utilized from electrodes positioned in the ear canal (EarEEG) for adapting hearing-aid processing to suite the individual listeners and situation. / Att förstå tal i brus kan vara svårt, speciellt när man lider av en hörselnedsättning. Denna avhandling undersöker beteende- och elektrofysiologiska data med föremålet att bestämma hur de påverkas av hörselskada (intern försämring) och lyssningssituation (extern försämring). Hypotesen att båda intern och extern försämring av talsignalen resulterar i mer aktivering av arbetsminnet under bearbetning av talsignaler har undersökts i fyra studier. Beteendedata visade att talförståelse försämrades med större hörselnedsättning, medan lägre arbetsminneskapacitet endast resulterade i sämre talförståelse när ljudkällorna inte var rumsligt sammanfallande. Elektrofysiologiska mätningar (EEG) gjorda under bearbetning av tal, visade at sämre hörsel associerades med högre inhibitorisk alfa-aktivitet (~10 Hz). Detta indikerar att personer med sämre hörsel upplevde en högre involvering av arbetsminnet under lyssningsuppgiften. Då nivån av bakgrundsljud höjdes, visade personer med sämre hörsel ett sammanbrott av alfaaktiviteten, vilket tyder på att de nådde ett tak där ytterligare arbetsminnes-resurser inte kunde frigöras genom neural inhibition. Sämre hörsel var också förknippat med en reducerad förmåga till at fokusera uppmärksamheten på en av två samtidiga talare, förorsakat av en reducerad förmåga till neuralt att undertrycka den störande talsignalen. En ökning av nivån av bakgrundsljud minskade förmågan att inkoda den relevante talsignalen. Att intern och extern försämring påverkade respektive inkodning av störande och relevant tal, indikerar att de två tal-strömma är neuralt behandlas som oavhängiga objekt. Denna avhandling demonstrerar för första gången att hörselskada förorsakar ändringar i den inducerade neurale aktiviteten under bearbetningen av talsignaler. I avhandlingens sista artikel förslås det preliminärt att neural aktivitet kan upptas från elektroder placerade i hörselgången som kan användas till att kontrollera hörapparat signalbehandling. / <p>Funded by the Oticon Foundation. Project number: 11-2757.</p>

Die Informations- und Kommunikationstechnologien haben die Arbeitswelt grundlegend verändert. Durch den Einsatz komplexer, hochautomatisierter Systeme werden an die kognitive Leistungsfähigkeit und Belastbarkeit von Arbeitnehmern hohe Anforderungen gestellt. Über die Ermittlung der psychischen Beanspruchung des Menschen an Arbeitsplätzen mit hohen kognitiven Anforderungen wird es möglich, eine Über- oder Unterbeanspruchung zu vermeiden. Gegenstand der Dissertation ist deshalb die Entwicklung, Implementierung und der Test eines neuen Systems zur kontinuierlichen Bewertung psychischer Beanspruchung an informationsintensiven Arbeitsplätzen auf Basis des Elektroenzephalogramms. Im theoretischen Teil der Arbeit werden die Konzepte zur Definition der psychischen Beanspruchung und Modelle zur Beschreibung der menschlichen Informationsverarbeitung zusammengestellt. Die Auswertung einer Reihe von Experimenten ist die Basis für die Konzeption und den Test des neuen Systems zur Indexierung der psychischen Beanspruchung. Die Aufgabenbatterie, die Stichprobenbeschreibung, der Versuchsaufbau und -ablauf sind Bestandteil des experimentellen Teils der Arbeit. Während der Aufgabenlösung wird von den Probanden das Elektroenzephalogramm mit 25 Kanälen abgeleitet. Es folgt eine Artefakteliminierung, für die ein neues automatisch und in Echtzeit arbeitendes Verfahren entwickelt wurde. Die Klassifikation und damit die Indexierung von Segmenten des Elektroenzephalogramms in die Klassen niedriger, mittlerer oder hoher Beanspruchung erfolgt auf Basis einer ebenfalls neu entwickelten Methode, deren Grundlage Dual Frequency Head Maps sind. Damit ist ein vollständiges System entstanden, das die einzelnen Verfahrensschritte integriert und die Aufgabenstellung der Arbeit erfüllt: Es kann an informationsintensiven Arbeitsplätzen eingesetzt werden, um kontinuierlich die Bewertung der psychischen Beanspruchung auf Basis des Elektroenzephalogramms vorzunehmen. / Advanced information and communication technology has fundamentally changed the working environment. Complex and highly automated systems impose high demands on employees with respect to cognitive capacity and the ability to cope with workload. The registration of mental workload of employees on-site at workplaces with high cognitive demands enables preventing over- or underload. The subject of this dissertation is therefore the development, implementation and testing of a novel system for continuous assessment of mental workload at information intensive workplaces on the basis of the electroencephalogram. In the theoretical section of the thesis concepts for defining mental workload are given; furthermore, models for describing human information processing are introduced and the relevant terminology such as strain, workload, and performance is clarified. Evaluation of an array of experiments with cognitive tasks forms the basis for the conceptual design and testing of the novel system for indexing mental workload. Descriptions of these tasks, the sample, the experimental set-up and procedure are included in the experimental section. The electroencephalogram with 25 channels was recorded from the subjects while performing the tasks. Subsequently, an artifact elimination was carried out, for which a new, automated, and real-time capable procedure has been developed. Segments from the electroencephalogram are classified and thusly indexed into classes of low, medium, and high workload on the basis of a likewise newly developed method, whose central element are Dual Frequency Head Maps. Hence, a complete system emerges that integrates the single processing steps and satisfies the scope of this thesis: It can be applied on-site at information intensive workplaces for continuous assessment of mental workload on the basis of the electroencephalogram.

Trotz zahlreicher Untersuchungen lässt sich bei der Zwangsstörung noch kein einheitliches, alle Befunde integrierendes Krankheitsmodell formulieren. Die Verarbeitung von emotionalen Reizen könnte bei Personen mit Zwangsstörungen verändert sein. Dies trägt möglicherweise zur Entwicklung und Aufrechterhaltung der Störung bei. Das Ziel der vorliegenden Arbeit war es, spezifische Komponenten dieser Verarbeitung zu untersuchen. Zuerst wurde in zwei unterschiedlichen Studien überprüft, ob die Orientierung der Aufmerksamkeit zu neuen Reizen bei Patienten mit Zwangsstörungen verstärkt ist. Zu diesem Zweck wurden durch neue Reize evozierte Potentiale im Elektroenzephalogramms (EEG) gemessen. Anschließend wurde in einer Studie überprüft, ob das Verhältnis der Aktivierungen von dem Vermeidungs- zum Annäherungssystem bei den Betroffenen verändert ist. Dies lässt sich an Hand der Ermittlung der hemisphärischen Verteilung von Alpha-Wellen in frontalen Hirnregionen feststellen. Die Ergebnisse der ersten beiden Studien ergaben, dass Patienten unabhängig vom emotionalen Kontext eine stärkere Aufmerksamkeitshinwendung zu neuen Reizen zeigen (Studie 1), was allerdings nicht beobachtet wurde, wenn die neuen Reize innerhalb des Aufmerksamkeitsfokus lagen (Studie 2). Dieses Ergebnis wurde als überaktives Gefahrenerkennungssystem bei Patienten interpretiert. Weiterhin ließ sich feststellen, dass Patienten im Vergleich zu gesunden Kontrollen in frontalen Hirnregionen eine Verlagerung der Alpha Asymmetrie zur linken Gehirnhemisphäre aufwiesen (Studie 3). Dieser Befund wurde unabhängig von einer Stimulierung durch emotionale Reize gemacht. Er lässt sich als stärkere Aktivierung des Vermeidungs- im Verhältnis zum Annäherungssystem deuten. Zusammengefasst zeigte sich bei Patienten mit Zwangsstörungen eine veränderte Verarbeitung von emotionalen Reizen. Aus diesen Befunden können spezifische Empfehlungen für die Behandlung der Störung abgeleitet werden. / It is so not possible to formulate a disease model of obsessive-compulsive disorder (OCD) that integrates all the results of the many studies carried out. The neural processing of emotional stimuli might be altered in people with OCD. This might play an important role in the development and maintenance of OCD. The present work aimed to investigate specific components of the neural processing of emotional stimuli. The first two studies examined if the orienting of attention towards novel stimuli is enhanced in patients with OCD. For this purpose the event-related brain potentials evocated by novel stimuli in the electroencephalogram were recorded. The third study tested if the relationship between the withdrawal-avoidance mode and the approach mode of the motivational brain system is altered in OCD patients. This can be assessed by the hemispheric distribution of alpha power in frontal brain regions. The results of the first two studies showed that the orienting of attention towards novel stimuli is enhanced in patients with OCD independently of the emotional context condition (study 1), which could not be observed if the novel stimuli were listened to in active attentional mode (study 2). This was interpreted as a hypersensitive threat detection system. Further, it was found that patients showed a shift of frontal alpha activity to the left hemisphere compared to healthy control subjects (study 3). This result was independent of the viewing of emotional stimuli. It can be concluded that the avoidance mode is relatively increased in patients with OCD. Taken together, patients showed an altered neural processing of emotional stimuli. Specific recommendations for he treatment of the disorder can be drawn out of them.

Um dos modelos experimentais mais utilizados para estudar a epilepsia do lobo temporal (ELT) é o abrasamento (kindling) por estimulação elétrica diária da amígdala, o abrasamento elétrico convencional. Uma alternativa rápida e eficaz a esse modelo é o abrasamento elétrico rápido, também capaz de gerar crises límbicas, porém com 10 estímulos elétricos aplicados ao dia, por 2 dias. No 3º dia é aplicado um estímulo elétrico adicional, o 21º estímulo, quando podem ser testadas drogas antiepilépticas ou estudados mecanismos de plasticidade ou memória. Entre as principais áreas ativadas nas crises límbicas encontram-se o complexo amigdalóide, a formação hipocampal, o córtex piriforme e neocórtices adjacentes. O envolvimento de estruturas olfatórias na ELT é antigo e estudos indicam que a exposição a um estímulo olfatório é capaz de suprimir, inibir ou induzir a ocorrência de crises. Todas as evidências clínicas e experimentais dão suporte científico para a hipótese de que a estimulação olfatória com o 2,5-Dihydro-2,4,5-trimethylthiazoline (TMT), uma potente substância química, derivada das fezes de raposa e que biologicamente representa o cheiro de predador pode influenciar no processo de crises evocadas por estimulação elétrica da amígdala. O objetivo geral do presente estudo foi avaliar a influência da apresentação do estímulo olfatório com TMT nas crises epilépticas de ratos Wistar, submetidos ao abrasamento elétrico rápido da amígdala. Para tanto, os parâmetros químicos do TMT foram avaliados, bem como as respostas comportamentais de ratos Wistar machos naives submetidos ao estímulo olfatório com diferentes doses de TMT. Na sequência, um novo grupo de ratos Wistar machos naives foi submetido ao protocolo de abrasamento elétrico rápido da amígdala com a aquisição dos registros eletrencefalográficos (EEGráficos) do córtex piriforme, formação hipocampal além do complexo amigdalóide. Após abrasados os animais foram expostos ao TMT ou água destilada, previamente ao 21º estímulo elétrico. Posteriormente o tecido cerebral foi processado (perfundido, crioprotegido, congelado e cortado) e então foram feitas as técnicas histoquímicas de: Nissl e Fluoro-Jade C (FJC, marcador de neurodegeneração). As respostas comportamentais foram analisadas mediante o uso do Índice de Gravidade para Crises Límbicas e da neuroetologia. Adicionalmente foi avaliada a expressão EEGráfica do 1º, 20º e 21º estímulos e verificada a presença/ausência de neurodegeneração em regiões do sistema límbico. Os resultados da análise comportamental obtidos nesse estudo foram comparados com os obtidos no protocolo de estimulação olfatória com TMT nas crises audiogênicas agudas de ratos da cepa WAR. O TMT desencadeou reações de medo e modificou as sequências comportamentais, reduziu a atividade motora e os comportamentos de autolimpeza. Dados qualitativos da cromatografia gasosa e algoritmos matemáticos possibilitaram estabelecer as concentrações na câmara para as diferentes doses de TMT. Além disso, a cromatografia gasosa identificou que 30 minutos é o tempo necessário para saturação e dessaturação da câmara ao TMT, e indicou uma saturação homogênea do interior dessa câmara. O TMT puro no abrasamento elétrico rápido em ratos Wistar foi capaz de reduzir significativamente o Índice de Gravidade para Crises Límbicas comparado à água, corroborando os dados neuroetológicos que indicam o efeito supressor do TMT nas crises, tanto para o modelo de abrasamento elétrico rápido quanto para as crises audiogênicas agudas. Os resultados da duração da pós-descarga EEGráfica primária no 21º estímulo foram inconclusivos, sendo necessárias outras análises empregando diferentes métodos analíticos. Com a técnica de FJC não foi possível verificar morte celular por necrose em qualquer região cerebral avaliada. / One of the most widely used experimental models to study temporal lobe epilepsy (TLE) is the kindling by electrical daily stimulation of the amygdala, the conventional kindling. A rapid and effective alternative to this model is rapid electrical kindling, also capable of generating limbic seizures, but with 10 electrical stimuli applied per day for 2 days. On the 3rd day an additional electrical stimulus is applied, the 21st stimulus, when antiepileptic drugs can be tested or mechanisms of plasticity and memory can be studied. Among the main areas activated in limbic seizures are the amygdaloid complex, the hippocampal formation, piriform cortex and adjacent neocortices. The involvement of the olfactory structures in TLE is old and studies indicate that exposure to an olfactory stimulus is capable to suppress or inhibit or induce the occurrence of seizures. All the clinical and experimental evidences provide scientific support for the hypothesis that the olfactory stimulation with 2,5-Dihydro-2,4,5-trimethylthiazoline (TMT), a powerful chemical substance derived from fox feces which biologically represents the \"predator smell can influence the seizures process evoked by electrical stimulation of the amygdala. The overall objective of this study was to evaluate the influence of olfactory stimulation with TMT in seizures of Wistar rats subjected to rapid electrical kindling of the amygdala. Therefore, the chemical parameters of TMT were evaluated, as well as behavioral responses of naive male Wistar rats exposed to the olfactory stimulus with different concentrations of TMT. Other group of rats was electrically stimulated in the amygdaloid complex, following the protocol of rapid electrical kindling and the electroencephalographic recordings (EEGraphic) obtained from the piriform cortex, hippocampal formation in addition to the amygdaloid complex. After scorched the animals were exposed to TMT or distilled water, prior to the 21st electrical stimulation. Subsequently the cerebral tissue was processed (perfused, cryoprotected, frozen and sliced) and then processed for Nissl and Fluoro-Jade C histochemistry (FJC, a marker of neurodegeneration). The behavioral responses were analyzed by using the Severity Index for Limbic Seizures and neuroethology. In addition to EEG, reviewed after the 1st, 20th and 21th stimuli we also examined the presence/absence of neurodegeneration in regions of the limbic system. The results obtained in this study were compared with those obtained in the protocol of olfactory stimulation with TMT on acute audiogenic seizures of rats from the WAR strain. The TMT triggered fear reactions and modified the behavioral sequences, reduced motor activity and grooming behavior. Qualitative data from gas chromatography and mathematical algorithms made possible to establish the concentrations in the camera for the different doses of TMT. In addition, the gas chromatography helped to identify that 30 minutes is the time required for saturation and desaturation of the camera to TMT and indicated a homogeneous saturation of the interior of such camera. The pure TMT in rapid electrical kindling in Wistar rats was able to significantly reduce the Severity Index for Limbic Seizures, compared to water, corroborating the data of the neuroethology method indicating the suppressive effect of TMT in seizures, in both, the model of rapid electrical kindling as well as the acute audiogenic seizures. However, the results of the duration of the EEGraphic primary after-discharge at the 21th stimulus were inconclusive, requiring further analysis using different analytical methods. With the technique of FJC it was not observed necrotic cell death in any studied brain region.

Most signal processing methods were developed for continuous signals. Digital devices, such as the computer, process only discrete signals. This dissertation proposes new techniques to accurately define and efficiently implement an important signal processing method---the time--frequency distribution (TFD)---using discrete signals. The TFD represents a signal in the joint time--frequency domain. Because these distributions are a function of both time and frequency they, unlike traditional signal processing methods, can display frequency content that changes over time. TFDs have been used successfully in many signal processing applications as almost all real-world signals have time-varying frequency content. Although TFDs are well defined for continuous signals, defining and computing a TFD for discrete signals is problematic. This work overcomes these problems by making contributions to the definition, computation, and application of discrete TFDs. The first contribution is a new discrete definition of TFDs. A discrete TFD (DTFD) should be free from the sampling-related distortion known as aliasing and satisfy all the important mathematical properties that the continuous TFD satisfies. Many different DTFD definitions exist but none come close to attaining this ideal. I propose three new components which make up the DTFD: 1) a new discrete Wigner--Ville distribution (DWVD) definition which satisfies all properties, 2) a new discrete analytic signal which minimises aliasing in the DWVD, and 3) a new method to define and convolve the discrete kernel with the DWVD to produce the DTFD. The result: a DTFD definition that, relative to the existing definitions, better approximates the ideal DTFD. The second contribution is two sets of computationally efficient algorithms to compute the proposed DTFD. The first set of algorithms computes the DTFD exactly; the second set requires less memory than the first set by computing time- and, or frequency-decimated versions of the DTFD. Both sets of algorithms reduce the computational load by exploiting symmetries in the DTFD and by constructing kernel-specific algorithms for four different kernel types. The third, and final, contribution is a biomedical application for the proposed DTFD and algorithms. This application is to accurately detect seizure events in newborn electroencephalogram (EEG) signals. Existing detection methods do not perform well enough for use in a clinical setting. I propose a new method which is more robust than existing methods and show how using the proposed DTFD, comparative to an existing DTFD, improves detection performance for this method. In summary, this dissertation makes practical contributions to the area of time--frequency signal processing by proposing an improved DTFD definition, efficient DTFD algorithms, and an improved newborn EEG seizure detection method using DTFDs.

Le module de l'apprenant est l'une des composantes les plus importantes d’un Système Tutoriel Intelligent (STI). L'extension du modèle de l'apprenant n'a pas cessé de progresser. Malgré la définition d’un profil cognitif et l’intégration d’un profil émotionnel, le module de l’apprenant demeure non exhaustif. Plusieurs senseurs physiologiques sont utilisés pour raffiner la reconnaissance des états cognitif et émotionnel de l’apprenant mais l’emploi simultané de tous ces senseurs l’encombre. De plus, ils ne sont pas toujours adaptés aux apprenants dont les capacités sont réduites. Par ailleurs, la plupart des stratégies pédagogiques exécutées par le module du tuteur ne sont pas conçues à la base d’une collecte dynamique de données en temps réel, cela diminue donc de leur efficacité. L’objectif de notre recherche est d’explorer l’activité électrique cérébrale et de l’utiliser comme un nouveau canal de communication entre le STI et l’apprenant. Pour ce faire nous proposons de concevoir, d’implémenter et d’évaluer le système multi agents NORA. Grâce aux agents de NORA, il est possible d’interpréter et d’influencer l’activité électrique cérébrale de l’apprenant pour un meilleur apprentissage. Ainsi, NORA enrichit le module apprenant d’un profile cérébral et le module tuteur de quelques nouvelles stratégies neuropédagogiques efficaces. L’intégration de NORA à un STI donne naissance à une nouvelle génération de systèmes tutoriels : les STI Cérébro-sensibles (ou STICS) destinés à aider un plus grand nombre d’apprenants à interagir avec l’ordinateur pour apprendre à gérer leurs émotions, maintenir la concentration et maximiser les conditions favorable à l’apprentissage. / The learner module is the most important component within an Intelligent Tutoring System (ITS). The extension of the learner module is still in progress, despite the integration of the cognitive profile and the emotional profile, it is not yet exhaustive. To improve the prediction of the learner’s emotional and cognitive states, many physiological sensors have been used, but all of these sensors are cumbersome. In addition, they are not always adapted to the learners with reduced capacities. Beside, most of the pedagogical strategies that are executed by the tutor module are based on no-live collections of data. This fact reduces their efficiency. The objective of our research is to explore the electrical brain activity and use it as a communication channel between a learner and an ITS. To reach this aim, we suggest to conceive, to implement and to evaluate the multi-agent system NORA. Integrated to an ITS, this one became a Brain Sensitive Intelligent Tutoring System (BS-ITS). Agents of NORA interpret the learner’s brain electrical signal and react to it. The new BS-ITS is the extension of an ITS and enrich the learner module with the brain profile and the tutor module with a new Neuropedagogical Strategies. We aim to reach more categories of learners and help them to manage their stress, anxiety and maintain the concentration, the attention and the interest.

The functions of sleep remain enigmatic. One of the dominant, yet more contentious hypotheses is that sleep is involved in memory consolidation. A large body of evidence supports the role of rapid eye movement (REM) sleep in memory consolidation, especially in rodents. In humans, the role of REM sleep in memory consolidation has also been investigated, however it is unclear if it supports only one type of memory, or consolidation for several memory systems. Recent evidence suggests that non-REM is also involved in memory consolidation. The role of theta activity during REM and sleep spindles during non-REM may provide electrophysiological signatures reflecting memory consolidation processes. The studies presented here attempt to further investigate the electrophysiological characteristics of the learning-dependent changes in REM and slow wave sleep (SWS) in rats. A 2-stage model of memory consolidation is outlined here, and both steps of the model were investigated. Consistent with previous studies, REM increases were observed following avoidance training. During this period, theta power during REM sleep was increased compared to non-learning rats. Increased sleep spindle density during SWS was observed following REM increases. When REM sleep was suppressed by infusing the GABAB agonist baclofen into the pedunculopontine nucleus, avoidance performance acquisition was impaired. Baseline sleep spindles predicted whether rats were able to learn to make avoidance responses. Results suggest that both REM and SWS may be sequentially involved in memory consolidation processes. Discrete periods (windows) exist for REM and SWS when memory consolidation processes appear to take place. Theta activity during REM sleep from 17- 20 h on the first post-training day and sleep spindles during SWS from 21-24 h on the first post- training day are increased in learning rats and are related to memory performance. / Thesis (Ph.D, Neuroscience Studies) -- Queen's University, 2009-10-26 12:07:47.515

Neurological diseases in newborns are usually first revealed by seizures, which are characterised by a synchronous discharge of a large number of neurons. Failure to control seizures may lead to brain damage or even death. The importance of this problem prompted many researchers to look for accurate automatic methods for seizure detection. Nonstationarity and multicomponent behaviour of newborn EEG signals made this task very challenging. The significant overlap in the characteristic of background and seizure activities in newborn EEG signals added to the difficulty of seizure detection. This research uses time-frequency based methods for automatic seizure detection. Since time-frequency signal analysis methods use joint representation in both time and frequency domains, they proved to be very suitable for analysis and processing of nonstationary and multicomponent signals such as newborn EEG. Before using any seizure detector, the EEG data is pre-processed in order to reduce the noise effects using a time-frequency based technique. The proposed method is based on the singular value decomposition (SVD) technique applied to the matrix representing the time-frequency distribution (TFD) of the EEG signal. It has been shown that by appropriately filtering the singular vectors associated with the TFD, one can effectively enhance the desired information embedded in the signal. Neonatal EEG seizures can have signatures in both low frequency (lower than 10 Hz) and high frequency (higher than 70 Hz) areas. The seizure detection techniques proposed in the literature concentrated on using either low frequency or high frequency signatures but not both simultaneously. These methods tend to miss the seizures that reveal themselves only in one of the two frequency areas. In this research, we propose a detection method that uses seizure features in both low and high frequency areas. To detect EEG seizures using the low frequency signatures, an SVD-based technique is employed. The technique uses the estimated distribution function of the singular vectors associated with the time-frequency distribution of EEG epochs to discriminate between seizure and nonseizure patterns. The high frequency signatures of seizures are mostly the result of spike events in the EEG signals. To detect these spike events, the signal is mapped into the TF domain. The high instantaneous energy of spikes is reflected as a localised energy in the high frequency area of the TF domain. Consequently, a spike can be seen as a ridge in this area of the TF domain. It has been shown that during seizure activity there is regularity in the distribution of the interspike intervals. This feature has been used as the basis for discriminating between seizure and nonseizure patterns. The performance results obtained by applying the proposed methods on EEG signals extracted from a number of newborns show the superiority of these methods over the existing ones.