<p>This dissertation examines the fiction of three contemporary American writers – Joan Didion, Don DeLillo and Paul Auster – who interrogate the legacy of the American sublime in its contemporary configurations and reconfigurations. The texts that I have selected by each writer dramatize and question how and why the American sublime remains a fundamental way for American culture to conceptualize power as an expression of American identity and progress. In turn, what each text conveys is the destructive consequences that often follow with investing natural phenomena, technology, cultural sites and practices with power that elicits the particular qualities of awe and terror unique to the American sublime. Above all, these texts illuminate why American culture continues to produce, reproduce and popularize experiences and images of sublimity within cultural sites, practices, art and literature.</p> <p>Moreover, by emphasizing that these texts locate the American sublime as a culturally produced experience, my analysis develops from – but also departs from – the most recent book-length studies of the sublime and American fiction. The work of scholars such as Barbara Claire Freeman, Joseph Tabbi and Christope Den Tandt who have considered the sublime in relation to gender, technology and urban landscapes complement my approach to the cultural impact of the American sublime in the fiction of Didion, DeLillo and Auster. At the same time, my examination of the ways in which their fiction accounts for the dissemination of the American sublime through art and literature as well as popular culture, brings to the forefront an important feature each text shares – the possibility that art might contest – rather than reinscribe – traditional configurations or reconfigurations of American sublimity.</p> / Doctor of Philosophy (PhD)

L'activité de notre cerveau est intrinsèquement rythmique : des oscillations sont observées à tous les niveaux de son organisation. Cette rythmicité de l'activité cérébrale influence notre perception. En effet, au lieu de superviser continuellement notre environnement, notre cerveau effectue de brèves " clichés " du monde extérieur (entre 5 et 15 par seconde). Cela crée des cycles perpétuels : notre perception visuelle fluctue en fonction de la phase de l'oscillation sous- jacente. De nombreuses données témoignent du fait que les oscillations cérébrales à différentes fréquences sont fondamentales à la formation de notre perception visuelle. Lors de cette thèse, nous avons utilisé le Paradigme de Bruit Blanc comme outil pour comprendre l'influence des oscillations sur la perception visuelle et qui par extension pourra être utilisé pour contrôler cette perception. Le paradigme de bruit blanc visuel utilise des séquences de flashs dont la luminance varie aléatoirement (créant ainsi du " bruit blanc "), comme stimuli, qui contraignent l'activité cérébrale de manière prédictible. Les réponses impulsionnelles à ces séquences de bruit blanc sont caractérisées par une composante oscillatoire forte dans la bande alpha (~10Hz), similaire à un écho perceptuel. Puisque les réponses impulsionnelles sont un modèle de la réponse de notre cerveau à un flash dans la séquence de bruit blanc, elles peuvent être utilisées pour reconstruire (plutôt qu'enregistrer) l'activité cérébrale en réponse à de nouvelles séquences de stimulation. Par ailleurs, des cibles ont été introduites au sein des séquences de bruit blanc à un niveau proche du seuil de perception, et le décours temporel de cette activité reconstruite autour de la présentation des cibles a été extrait. Ainsi, l'EEG reconstruit peut être utilisé pour étudier l'influence de ces oscillations contraintes sur la perception visuelle, indépendamment des autres types de signaux généralement enregistrés dans l'EEG. Dans un premier temps, nous avons validé le paradigme de bruit blanc en montrant que : 1) les séquences de bruits blancs influencent bien la détection des cibles, 2) les échos perceptuels évoqués par les séquences de bruit blancs sont stables dans le temps, 3) ces échos sont un bon modèle de l'activité cérébrale enregistrée par EEG, et 4) leurs bases neuronales se situent dans les aires visuelles primaires. Dans un second temps, nous avons étudié la relation entre ces oscillations cérébrales contrôlées par la séquence de bruit blanc et la détection des cibles. Ici, nous montrons que l'activité EEG reconstruite nous aide à déterminer la véritable latence à laquelle la phase de l'oscillation (thêta) influence la perception. De plus, nous avons aussi montré que l'amplitude de l'oscillation (alpha) influence la détection des cibles et ce, indépendamment des fluctuations des facteurs endogènes (tel que l'attention). Enfin, tirant parti de ce lien entre oscillation et perception, nous construisons deux algorithmes qui permettent de contrôler la perception des sujets. Tout d'abord, nous mettons au point un modèle " universel " de la perception qui permet de prédire, pour n'importe quel observateur, si une cible dans une séquence de bruit blanc sera vue ou non. Ensuite, nous construisons un modèle individuel qui utilise l'écho perceptuel de chaque sujet comme clé de cryptage et nous permet de présenter des cibles à des moments où la cible sera détectée par un sujet seulement au détriment de tous les autres sujets, créant ainsi une sorte de système de cryptage neuronal (" Neuro-Encryption "). / Our brain activity is inherently rhythmic: oscillations can be found at all levels of organization. This rhythmicity in brain activity gives a rhythm to what we see: instead of continuously monitoring the environment, our brains take "snapshots" of the external world from 5 to 15 times a second. This creates perceptual cycles: depending on the phase of the underlying oscillation, our perceptual abilities fluctuate. Accumulating evidence shows that brains oscillations at various frequencies are instrumental in shaping visual perception. At the heart of this thesis lies the White Noise Paradigm, which we designed as a tool to better understand the influence of oscillations on visual perception and which ultimately could be used to control visual perception. The White Noise Paradigm uses streams of flashes with random luminance (i.e. white noise) as stimuli, which have been shown to constrain brain oscillations in a predictable manner. The impulse response to WN sequences has a strong (subject specific) oscillatory component at ~10Hz akin to a perceptual echo. Since the impulse response is a model of how our brains respond to one single flash in the sequence, they can be used to reconstruct (rather than record) the brain activity to new stimulation sequences. We then present near-perceptual threshold targets embedded within the WN sequences and extract the time course of these predicted/reconstructed background oscillations around target presentation. Thus, the reconstructed EEG can be used to study the influence of the oscillatory components on visual perception, independently of other types of signals usually recorded in the EEG. First, we validate the White Noise Paradigm by showing that: 1) the WN sequences do modulate behaviour, 2) the perceptual echoes evoked by these WN sequences are stable in time, 3) they are a (relatively) good model of the subject's recorded brain activity and 4) their neuronal basis can be found in the early visual areas. Second, we investigate the relationship between these constrained brain oscillations and visual perception. Specifically, we show that the reconstructed EEG can help us recover the true latency at which (theta) phase influences perception. Moreover, it can help us uncover a causal influence of (alpha) power on target detection, independently from any fluctuation in endogenous factors. Finally, capitalizing on the link between oscillations and perception, we build two algorithms used to control the perception of subjects. First, we build a "universal" forward model which can predict for any observer whether a particular target will be seen or not. Second, we build a subject-dependent model which can predict whether a particular subject (for whom EEG was recorded previously) will perceive a given target or not. Critically, this can be used to present targets optimized to be perceived by one subject only, to the detriment of all other subjects, creating a sort of "Neuro-Encryption" system.

Artificial Neural Networks (ANNs) can be viewed as a mathematical model to simulate natural and biological systems on the basis of mimicking the information processing methods in the human brain. The capability of current ANNs only focuses on approximating arbitrary deterministic input-output mappings. However, these ANNs do not adequately represent the variability which is observed in the systems’ natural settings as well as capture the complexity of the whole system behaviour. This thesis addresses the development of a new class of neural networks called Stochastic Neural Networks (SNNs) in order to simulate internal stochastic properties of systems. Developing a suitable mathematical model for SNNs is based on canonical representation of stochastic processes or systems by means of Karhunen-Loève Theorem. Some successful real examples, such as analysis of full displacement field of wood in compression, confirm the validity of the proposed neural networks. Furthermore, analysis of internal workings of SNNs provides an in-depth view on the operation of SNNs that help to gain a better understanding of the simulation of stochastic processes by SNNs.

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ADHD affects executive functions and pharmacological treatment is the most common intervention. Medication is ineffective for some and psychosocial interventions are scarcely available. CBT that teaches organizational skills for managing ADHD-symptoms has shown promising results. Smartphones can help individuals perform executive tasks such as planning and organizationand they could beefficacious as a support tool for ADHD patients. The current study is aRCT that compares an online course (n=29) based on previouslyeffective CBT treatments for ADHD to a wait-list control (n=29). Theintervention focused on teaching the use of an online calendar and smartphone apps. The intervention brought significant improvement (p &lt; 0.001) to participants regarding ADHD symptoms and 38% of participants were considered clinically significantly improved. This indicates that online treatments using IT-tools for ADHD is effective and that smartphones can be used as a tool for aiding individuals with impairments in executive functions.

Do you think we can concentrate in noisy situations? I bet most of us would spontaneously answer “no” to this apparent simple question. Although we admit it is intuitively the best answer to give, this thesis aims to evidence that it is not always true and that, under certain circumstances, noise can be beneficial.<p><p>To appropriately discuss this question, it is necessary to answer others, such as: what is concentrating, paying attention? And, what is noise? Everyone has an idea of what attention is, and can give examples of situations in which it is required: school, work, driving, listening to our parents’ requests and so forth. But who could say that we can fully control attention like if we had a button to press, switching on and off according to the context? When we were little, my father used to say to my brothers and me: “Ok, you did not do this on purpose, but, please, pay attention to your attention”. Well, I can say now that it is not that easy and certainly not for everyone. In the population, around five percent of children and adults meet serious difficulties to pay attention. These people, more than others, often express their deficit with excessive distraction and/or hyperactivity as well as impulsivity. These multiple symptoms, for the individual who lives these behavioral excesses, represent an issue for his/her everyday-life: at school, at work, driving, trying to listen to his/her parents’ requests, etc.<p><p>Such symptoms refer to a syndrome called attention-deficit/hyperactivity disorder (ADHD). Although the definition of this syndrome has changed across the course of History, the first descriptions of ADHD go back to 1798. Since, a lot has been written about this disorder, which we do not fully understand yet. Beyond these simple words, “inattention, impulsivity, hyperactivity”, a consequent number of etiologies (environmental, genetic, psychosocial), subtypes, comorbidities, and outcomes reflect the enormous heterogeneity of the phenotypes that are found in this syndrome. The main treatment offered to individuals with ADHD is a psychostimulant drug called methylphenidate. This medication, acting mainly on dopaminergic brain functioning, has proven efficacy regarding ADHD symptoms. However, it has several limitations. For instance, its use remains controversial in the society; it causes side effects and around 30% of individuals with ADHD do not respond to this treatment. These mentioned limitations, among others, highlight the necessity to find alternative ways to reduce ADHD symptoms.<p><p>This is the main objective of this thesis. To do so, we will investigate a counterintuitive phenomenon. In certain situations, what can be called noise might improve cognition and, consequently, potentially reduce the symptoms associated with ADHD. As mentioned in the beginning of this preamble, one could think that everything unnecessary in our direct environment is a potential distraction. Intuitively, a sensible person would suggest that individuals prone to distraction, as those with ADHD, would benefit from a stimulation- free environment to improve attention and reduce impulsivity as well as hyperactivity. However, already in the 1970’s, authors such as Zentall (1975) developed a theory supported by empirical data, i.e. the optimal stimulation theory, showing that adding stimulation in the environment (with pictures, posters, music, colors, etc.) might improve symptoms of children with ADHD. Successively, many theories and findings were developed and related to the observation that the environmental context affects attention, hyperactivity and impulsivity. For instance, the delay aversion theory (Sonuga-Barke, Taylor, Sembi, & Smith, 1992) suggests that, as children with ADHD are motivated to discount delay, the inattentive, overactive and impulsive behaviors are the expression of such aversion when they cannot avoid the delay. Related to this theory, adding stimulation in the environment has evidenced hyperactivity and impulsive choice reduction (Antrop, Roeyers, Van Oost, & Buysse, 2000; Antrop et al. 2006). Another theory advocates that the ADHD-related symptoms are explained in terms of energetic dysfunction (Sergeant, 2000). For instance, children with ADHD would meet difficulties to adjust their internal state (e.g. their arousal) required for a task. Accordingly, Sergeant (2000) suggested that performance is influenced not only by cognitive capacity but also by environmentally determined levels of arousal and showed the extent to which variations in these energetic factors can be managed to ensure optimal performance. A recent theory, called the Moderate Brain Arousal model (Sikstrom & Soderlund, 2007), particularly caught our interest. This theory postulates that white noise has beneficial effect on cognition. The first study of these authors (Soderlund, Sikstrom, & Smart, 2007) supported their hypothesis, showing that children with ADHD improved their episodic memory performance when they were exposed to white noise. This is, to our knowledge, the first study that evidenced such improvement with white noise, considered as extra-task stimulation, in children with ADHD.<p><p>The objective of this thesis is to investigate the potential beneficial effect of noise in individuals with and without ADHD regarding attentional and executive functioning. We will first review, in the first chapter of this Introduction, the general aspects of ADHD: definition criteria, prevalence, etiologies, treatments and outcomes. In the second chapter, we will present the main theories and findings related to this syndrome and to our main objective.<p>After the Introduction, we will describe the different experimental studies that we have carried out in the context of this thesis. Hereunder, we propose a short overview of these studies.<p>The first study of this thesis is a pilot study, aimed to validate the relevance to use event- related potentials (ERPs) in children with and without ADHD to further investigate noise effect. Accordingly, the second study investigated noise effect on behavioral and ERPs aspects in children with and without ADHD. To do so, children performed a visual cued Go/Nogo. They were also submitted to a neuropsychological assessment. Afterwards, in a third study, we used the same paradigm in adults with and without ADHD. Here, we also added a music condition to investigate another stimulation than noise.<p><p>In the fourth study, we decided to explore the effect of noise in a more ecological environment. To do so, we used a virtual reality tool that allowed to immerse the children in a virtual classroom environment. Children with and without ADHD were then assessed, being immersed in a classroom, with a continuous performance task (CPT) presented on the blackboard while several auditory and visual realistic distracters emerged during the test. Children performed the task with and without white noise exposure as well as a neuropsychological assessment. In the fifth study, we used the virtual classroom to investigate noise effect on interference control. Children with and without ADHD were submitted to a bimodal virtual reality Stroop (with auditory and visual target stimuli) and to a neuropsychological assessment. Finally, in a last study, we explored the effect of noise in consecutive young adults. Immersed in the virtual classroom, they were submitted to the CPT task with and without white noise. ADHD questionnaires and a neuropsychological assessment were also undertaken.<p><p>To end this thesis, we will discuss to what extent our studies allowed going one step further in the investigation of “on what, with whom, when and where” noise can be beneficial. We will discuss all our studies and results in the light of the theories and findings exposed in the Introduction. Finally, we will comment the clinical validation of these results.<p><p><p> / Doctorat en Sciences Psychologiques et de l'éducation / info:eu-repo/semantics/nonPublished

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We approximate the solution of a quasilinear stochastic partial differential equa- tion driven by fractional Brownian motion B_H(t); H in (0,1), which was calculated via fractional White Noise calculus, see [5].

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