Dissertations / Theses on the topic 'Adaptation visuelle'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Adaptation visuelle.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
Cohen, Salomon Yves. "Adaptation au scotome central." Paris 6, 2003. http://www.theses.fr/2003PA066063.
Roux, Armelle. "Habituation de la fixation visuelle chez le bébé de 4 mois." Lille 3, 2006. http://www.theses.fr/2006LIL30056.
Habituation can be observed in newborn, babies, fetuses, human adults and even, at another level, the nervous cell (Kandel, 1979). We have chosen to study habituation with the 4-month-old-baby as many other authors did (Cohen, 1972 ; Lécuyer, 1989 ; Colombo, 1993). The experiments held in the context of this thesis aim at testing an interpretation of attention holding, referring to the physiological process of sensitization. This interpretation is proposed as an alternative to Cohen's model (1972). Our results question the idea according to which habituation results from the necessity for the baby to build up an inner model of the target as proposed, for instance, by Cohen's model (1972). As a matter of fact, once the habituation phase is over, the stimulus characteristics should be stored in memory if Cohen's model is correct. Hence, the baby should no longer stare at the target, which is not the case in our experiments. It seems, then, that the amount of attention granted to a stimulus does not depend uniquely on its physical characteristics but that fixation of a familiar image can be restored after sensitization
Lê, Sandra. "Neuropsychologie et neuro-imagerie fonctionnelle des troubles acquis de la perception visuelle : plasticité neuronale et adaptation comportementale." Toulouse 2, 2002. http://www.theses.fr/2002TOU20051.
Through an exceptional case of visual agnosia (SB) acquired in childhood, this thesis constitutes a neuropsychological and neuro-imaging approach to visual perception. Lesions affected the ventral stream (VS) bilaterally and the right dorsal stream (DS). Visual tests showed that SB uses a "feature by feature" visual recognition strategy. Two experiments revealed that SB may have retained a spared module for implicit face processing. A visual form detection experiment in fMRI showed that SB may have developed visual stategies involving the left DS and palliating for the quasi-absence of the VS. These observations showed us the necessity to further investigate the "role" palyed by the ventral and dorsal streams in visual perception. Finally, a neuro-imaging study was conducted on the visual residual discrimination of motion in hemianopes and showed that activation in the lateral occipital areas, but not in the calcarine cortex, is necessary for motion discrimination in these patients
FERREL, CAROLE. "Production et controle des mouvements de pointage de cible : adaptation a une decorrelation vision-proprioception." Grenoble 2, 1998. http://www.theses.fr/1998GRE29049.
Several studies on motor control suggest that amplitude and direction parameters involve different processes. In remote operation, operators carry out various visual-motor tasks while viewing their hands by means of video feedback. This situation usually entails a discrepancy between the information provided by visual and proprioceptive systems. Among numerous studies that analyzed the adaptation of the perceptual-motor system to visual spatial distortions, many focused on perceptual-motor adaptation to directional distortions. The present study concerns the adaptation of motor system to the distortion of distance when the production of movement is visually controlled through a video display. The subjects had to perform a pointing movement with information provided by video screen. By changing the zoom of the camera, the amplitude of the movement perceived on the screen was different from the actual movement. Results showed that the movement adapted more quickly to the distortions of distance than to directional distortions. However, adaptation did not transfer to other situations since it was specific to the target and scale. Adaptation occurred at task level, i. E. , was based on information relating to the displacement of the hand. Most of subjects tended to use mainly the information provided by the visual system. The spatial cues (e. G. Reference frame, known objects) facilitated this adaptation. In conclusion, adaptation to distance distortion depends on two processes. The first one leads to a local visual-motor adaptation. The second one, which is necessary for the transfer of adaptation, is slower and involves a general remapping of the whole grasping space
Lévy-Bencheton, Delphine. "Perception visuelle et plasticité oculomotrice : aspects fondamentaux et application clinique." Phd thesis, Université Claude Bernard - Lyon I, 2013. http://tel.archives-ouvertes.fr/tel-00926062.
Ben, Tourkia Slim. "L'enseignement de mal voyants en France et en Tunisie : de la défiance visuelle au déficit pédagogique : le cas de l'enseignement des mathématiques à l'école." Thesis, Paris 8, 2018. http://www.theses.fr/2018PA080009.
Teaching the BVI (Blind and Visually Impaired) is the foundation of their learning and integration in both school and society, and is based on policies implemented in various countries. In France and in other countries, integration policies, in an open and specialized setting, are formed for the BVI. Field studies in France and in Tunisia show that with specific media and materials, the BVI were able to learn Math, thus concretizing these integration policies
Ben, Tourkia Slim. "L'enseignement de mal voyants en France et en Tunisie : de la défiance visuelle au déficit pédagogique : le cas de l'enseignement des mathématiques à l'école." Electronic Thesis or Diss., Paris 8, 2018. http://www.theses.fr/2018PA080009.
Teaching the BVI (Blind and Visually Impaired) is the foundation of their learning and integration in both school and society, and is based on policies implemented in various countries. In France and in other countries, integration policies, in an open and specialized setting, are formed for the BVI. Field studies in France and in Tunisia show that with specific media and materials, the BVI were able to learn Math, thus concretizing these integration policies
Perreira, Da Silva Matthieu. "Modèle computationnel d'attention pour la vision adaptative." Phd thesis, Université de La Rochelle, 2010. http://tel.archives-ouvertes.fr/tel-00573844.
Perreira, da Silva Matthieu. "Modèle computationnel d'attention pour la vision adaptative." Thesis, La Rochelle, 2010. http://www.theses.fr/2010LAROS317/document.
Providing real time analysis of the huge amount of data generated by computer vision algorithms in interactive applications is still an open problem. It promises great advances across a wide variety of fields : robotics, distance education, or new mouse-less and keyboard-less human computer interaction.When using scene analysis algorithms for computer vision, a trade-off must be found between the quality of the results expected, and the amount of computer resources allocated for each task. It is usually a design time decision, implemented through the choice of pre-defined algorithms and parameters. However, this way of doing limits the generality of the system. Using an adaptive vision system provides a more flexible solution as its analysis strategy can be changed according to the information available concerning the execution context. As a consequence, such a system requires some kind of guiding mechanism to explore the scene faster and more efficiently.In human, the mechanisms of evolution have generated the visual attention system which selects the most important information in order to reduce both cognitive load and scene understanding ambiguity.In this thesis, we propose a visual attention system tailored for interacting with a vision system (whose theoretical architecture is given) so that it adapts its processing according to the interest (or salience) of each element of the scene.Somewhere in between hierarchical salience based (ex: [Koch1985], then [Itti1998]) and competitive distributed (ex: [Desimone1995], then [Deco2004, Rolls2006]) models, we propose a hierarchical yet competitive and non salience based model. Our original approach allows the generation of attentional focus points without the need of neither saliency map nor explicit inhibition of return mechanism. This new real-time computational model is based on a preys / predators system. The use of this kind of dynamical system is justified by an adjustable trade-off between nondeterministic attentional behavior and properties of stability, reproducibility and reactiveness.Our experiments shows that despite the non deterministic behavior of preys / predators equations, the system exhibits interesting properties of stability, reproducibility and reactiveness while allowing a fast and efficient exploration of the scene. These properties are useful for addressing different kinds of applications, ranging from image complexity evaluation, to object detection and tracking. Finally, while it is designed for computer vision, we compare our model to human visual attention. We show that it is equally as plausible as existing models (or better, depending on its configuration)
Beaulieu, Véronique. "Étude de la visualisation géographique dans un environnement d'exploration interactive de données géodécisionnelles : adaptation et améliorations." Thesis, Université Laval, 2009. http://www.theses.ulaval.ca/2009/26354/26354.pdf.
Rose, Isabelle. "Les effets de la contingence lors d'une tâche d'habituation visuelle chez les nourrissons de 6 mois." Master's thesis, Université Laval, 2001. http://hdl.handle.net/20.500.11794/66132.
Rose, Isabelle. "Les effets de la contingence lors d'une tâche d'habituation visuelle chez les nourissons de 3 et 6 mois." Doctoral thesis, Université Laval, 2006. http://hdl.handle.net/20.500.11794/18309.
Lavoie, Chantale. "L'habituation visuelle chez le nourrisson de cinq mois : fidélité des mesures obtenues à l'aide d'un nouveau critère d'habituation." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ55596.pdf.
Cartron, Leila. "Perception de la polarisation de la lumière chez la seiche Sepia officinalis : développement, fonction et approche comparative." Caen, 2012. http://www.theses.fr/2012CAEN2076.
Rocher, Pierre-Olivier. "Transmodalité de flux d'images de synthèse." Thesis, Saint-Etienne, 2014. http://www.theses.fr/2014STET2026/document.
The use of video as an information dissemination support has become preponderant during the last few years. According to some analysts, by 2017 approximately 90% of the world's bandwidth will be consumed by video streaming services. These services have encouraged cloud gaming solutions to become more democratic. Such solutions have been devised in the context of strong development of the cloud-computing paradigm, and they were driven by the proliferation of mobile devices as well as growing network quality. The technologies used in this kind of solutions refer to as remote rendering. They allow the execution of multiple applications, while maximizing the number of clients per server. Thus, it is essential to control the necessary bandwidth to allow the required functionality of various services. The existing cloud gaming solutions in the literature use various methods of video compression to transmit images between sever and clients (pixels reigns supreme). However, there are various other ways of encoding digital images, including parametric map storage and a number of studies encourage this approach (for both image and video). In this thesis, we propose a hybrid representation of space in order to reduce the bit rate. Our approach utilizes both pixel and parametric approaches for the compression of video stream. The use of two compression techniques requires defining the area to be covered by different encoders. This is accomplished by including user to the life cycle of rendering, and attending to the area mostly concerned to the user. In order to identify the area an eye-tracker device was used on several games and several testers. We also establish a correlation between the characteristics of images and the type of game. This helps to identify areas that the player looks directly or indirectly (“maps of selective attention"), and thus, encoders are manager accordingly. For this thesis, we details and implement the architecture and algorithms for such multi-model encoder (which we call "transmodeur") as proof of concept. We also provide an analytical study of out model and the influence of various parameters on transmodeur and describe in effectiveness through an objective study. Our transmodeur (rendering system) has been successfully integrated into XLcloud project for rendering purposes. A number of improvement (especially in performance) will be required for production use, but it is now possible to use it smoothly using spatial resolutions slightly lower than 720p at 30 frames per second
Nicolas, Judith. "On the link between saccadic adaptation and visuospatial attention." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1024/document.
Attention and Saccadic Adaptation (SA) are critical components of visual perception, the former enhancing sensory processing of selected objects, the latter maintaining the eye movements accuracy towards them. Also, a similar dichotomy could be applied to both: voluntary saccades and endogenous attentional shifts follow internal goals while reactive saccades and exogenous shifts are elicited by sudden changes in the environment. Further, their neural substrates partially overlap and they impact each other behaviorally. This PhD work investigates the hypothesis of a functional coupling linking attention and SA in healthy humans. Our experimental contributions all rely on the measurement of attentional performances before and after an exposure to SA (or control). In the first study, we recorded brain magnetic fields to investigate neurophysiological bases of the reactive/exogenous coupling. In the second study, we compared exogenous orienting measured in a Posner-like paradigm before and after reactive SA. Finally, using the same design, the third experiment investigated the voluntary/endogenous modality. We found that SA increased gamma band activity and boosted the orienting of spatial attention. We thus propose that this functional coupling relies on neuronal populations co-activated by both oculomotor plasticity and attention in the Posterior Parietal Cortex (PPC). The initial activation would emerge from a dual effect of the cerebellum inhibiting the left PPC and activating the right PPC. This effect would increase the right hemispheric dominance and the leftward attentional bias. This work opens new perspectives for the rehabilitation of visuoattentional deficits
Imbert, Jean-Paul. "Adaptation du design des visualisations de type supervisions pour optimiser la transmission des notifications classées par niveau d’intérêt." Thesis, Toulouse, ISAE, 2014. http://www.theses.fr/2014ESAE0055/document.
Air traffic control is undergoing a great change due to the increase of traffic and the evolution of thecontrol tools. The greater number of aircrafts managed by the controller implies a much greater load ofinformation to deal with and memorize than before. A significant part of accidents’ causes is already dueto the problem of information perception and memorization which is worsened by the size of the controlscreens which are particularly critical concerning the perception of alarms and warnings displayed onthe radar image. The current design in France of those types of alerts which rely on color is controversialand an Aviation Safety bulletin recommended it should be improved. The perception of informationcontributing to a satisfactory situation awareness by the air traffic controllers is central to this thesis whichaims at making sure alarms and relevant information are detected early enough and according to prioritiesand that the corresponding actions are actually performed. To answer the issue at stake our first work focusdealt with the study of the controllers’ task so as to analyze the required information in order to achievecertain objectives and provide a task monitoring agent that could support them. The second work focusdealt with the notifications perception, more specifically in the peripheral vision and the conception ofdesigns such as to improve their perception and the study of their impact on the performance of the task.Thanks to a holistic approach based on the use of an ATC microworld (Laby) and the use of physiologicalsensors we managed to assess several notification designs. Several experiments have been conducted,one using eye-tracking aimed at measuring attention capacity of five designs and their impact on theperformance of the task. The second used neurophysiologic data and aimed at measuring the impact oftwo designs on the work load. The assessed designs enabled to conceive a notification system integratedin a new radar supervision together with the task monitoring agent. The last experiment conducted in thecourse of this work aimed at measuring the impact of this new position of control whose design is situationawareness oriented, on the detection of critical problems. The obtained results show the relevance ofthese new tools and their positive impact on the performance of the task by controllers as well as the needto assess, in a controlled experimental context, the characteristics of notification designs for supervisionvisualization
Bobet, Philippe. "Tete stéréoscopique, réflexes oculaires et vision." Grenoble INPG, 1994. http://www.theses.fr/1994INPG0174.
Fournier, Julien. "Adaptation of the simple or complex nature of V1 receptive fields to visual statistics." Paris 6, 2009. http://www.theses.fr/2009PA066426.
Leroy, Laure. "Interfaçage visuel stéréoscopique : diminution de la fatigue visuelle et caractérisation de la perception des formes." Phd thesis, École Nationale Supérieure des Mines de Paris, 2009. http://pastel.archives-ouvertes.fr/pastel-00005882.
Paris, Donnet Stéphanie. "Contrôle des saccades vers des cibles dans l'espace tridimensionnel : études en laboratoire et en situation naturelle de conduite automobile." Paris 5, 2003. http://www.theses.fr/2003PA05H062.
The first purpose of this thesis is to provide fundamental knowledge concerning adaptation mechanisms of the saccadic eye movement binocular co-ordination. Dichoptic devices creating a disparity between the two eyes images are used. Secondly, in the applied approach, the influence of information position inside the vehicle on ocular saccades spatio-temporal characteristics is studied using a movable display during day and night driving conditions. The results show that a very limited (2%) inequality in image size induces disconjugate adaptations of horizontal and vertical saccades for two distances (40 and 100 cm). Nevertheless, there are some differences in the quality of adaptation according to saccade types : horizontal versus vertical, visually guided versus memory-guided saccades. For example, tha ability to modify the co-ordination of vertical memory guided saccades is very idiosyncratic. This capacity could depend on convergence movements during the saccade and presence of natural vertical phoria. The results of applied studies allow defining the advantages and disadvantages of each position and identifying the optimal position to consult information rapidly and easily. This position corresponds to the location driver axis below the windshield. This conclusion is based on variables such as smaller percentage of consultation, reduced diversion time, and also on a subjective preference
Chazelle, Thomas. "Influence sociale sur la représentation corporelle : Approche expérimentale de l'effet des médias et des labels de poids sur des jugements de corpulence." Electronic Thesis or Diss., Université Grenoble Alpes, 2023. http://www.theses.fr/2023GRALS063.
Body representation is the set of cognitive functions that track the state of the body. It is involved in a variety of situations, such as the perception of the physical dimensions of the body, action, and the generation of attitudes towards the body. To perform these functions, it relies on the flexible use of a range of sensorimotor information, as well as on the individual's beliefs, expectations and emotions. Among the sources of information available about the body, social influence can be a risk, maintenance, and severity factor in body image distortions. However, while social influence on the attitudinal aspects of body representation is well established, there is little experimental evidence of such influence on its perceptual aspects. The aim of this thesis is to study the integration of social information into the perceptual dimension of the representation of body size. To this end, we conducted a series of experiments with young women, a demographic that is particularly prone to distortions of body representation. A first axis focuses on interpersonal influence by testing the effect of weight labels on perceptual judgments. To investigate their informational influence, we manipulated the reliability of multiple cues to study how they were combined. Our results indicate that weight labels have a limited influence on judgments of body size. A second axis focuses on another type of social influence, media influence. Visual overexposure to specific body types is associated with body dissatisfaction, and could help explain the perceptual and attitudinal distortions of body representation. In this context, visual adaptation to bodies could explain how prolonged exposure to thin bodies can lead to an overestimation of one's own body size. We tested some of the hypotheses of this adaptation theory of body image distortion. These experiments highlight some limitations of the adaptation account; in particular, it is uncertain whether adaptation effects can influence the representation that individuals have of their own bodies. In conclusion, our results suggest that the perceptual dimension of the representation of body size may be resistant to some types of interpersonal and media social influence
Simoncini, Claudio. "Intégration spatio-temporelle de l'information visuelle pour les mouvements oculaires et la perception : =Spatio-temporal integration of visual information for eye movements and perception." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM5065/document.
We focused on the impact of the statistical distributions of visual information on these various behavioral responses. We asked first how motion information is integrated to estimate speed in order to perform either a speed discrimination task or to control reflexive tracking eye movements. Next, we investigated how spatial distribution in textures affects both pattern recognition and fixational eye movements. To do so, we used a set of artificial stimuli that are naturalistic textures where we can maintain a tight control on their information contents as for instance their spatio-temporal frequency bandwidth. The first studies compared speed information decoding for ocular following eye movements and perceptual speed discrimination. We found a strong dissociation where ocular following take full advantage by the enlargement of the spatio-temporal frequency bandwidth while perceptual speed discrimination is largely impaired for large bandwidth stimuli. Such dissociation remains over a large temporal integration window. We propose an adaptive gain control mechanism to explain this opposite dependencies. The second series of experimental studies investigate the properties of fixation eye movements (microsaccade and saccade) as a function of the mean and variance of the spatial frequency content of visual static textures. We show that several characteristics of fixational saccades (location, direction and amplitude) varied systematically with the distribution of spatial frequencies. The spatial distribution of the fixation zones could be best predicted from the saliency maps of the stimuli
Froissard, Benoit. "Assistance visuelle des malvoyants par traitement d’images adaptatif." Thesis, Saint-Etienne, 2014. http://www.theses.fr/2014STET4004/document.
This thesis was done in the context of visual impaired needs analysis with the goal of new augmented reality visual assistance device development. The main goal of this work was the development of assistive device for mobility of visual impaired people by the use real-time image processing algorithm which take into account user needs and the context. The first postulate is the use of residual visual acuity of visual impaired people to allow them to see more information. The second postulate is the use only most useful information for visual impaired people for the understanding of the situation where are they. The first research axis was an analysis of needs of visual impaired to identify visual cues, which one we need to enhance to help them. To do this, I have done an immersive stage into a re-adaptation clinic for visually impaired. I have also done a questionnaire to identify and understand how current products answers partially to their needs. The second research axis was the development of a new image processing to answer identified needs. I have developed an interactive tools that allow the user to select the amount of edges for each situation, context. This detector optimizes its result to provide better results than others state of the art evaluated methods. This tool was evaluated and validated during visual test by visual impaired people. We have demonstrated that edges are one of the most important visual cues for visual impaired people to analyze a scene. The third research axis was the development of the augmented reality system to use my tool in a context of mobility. To do this, I have analyzed the needs of visual impaired people for this type of devices. I have also defined main requirements of the desired device for the processing unit, the camera and the display module. For display module, I have analyzed physiologic needs of visually impaired, in terms of profile, colors, and thickness to answer their needs. I have also developed an image generation model which takes into account many physiologic parameters of each observer to create visually comfortable images
Mathew, James. "Etude des mécanismes prédictifs sous-jacents à la coordination œil-main." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0329/document.
The ability to coordinate efficiently eye and hand actions is central for humans in everyday activities. Furthermore it is argued that the ability to predict the sensory consequences of self-initiated movements is crucial for skilled motor behavior. Here by means of a task in which participants were asked to track with the eyes a visual target that was moved by their hand, we investigated the predictive mechanisms underlying eye-hand coordination. In a first study, using a protocol in which participants had to adapt to rotated hand visual feedback, we show that these predictive mechanisms can be updated independently of the ability to perform accurate hand movements. In a follow up study we tested the effect of hand dominance, and showed that, despite obvious differences in the accuracy of hand movement control, the ability to predict visual consequences of right and left hand actions was similar. Finally, by means of transcranial magnetic stimulation, we tested the hypothesis that those predictive mechanisms rely on hand efferent signals from the primary motor cortex (M1). However our results failed to support this view, and instead suggest that if such a contribution exists, it must be upstream of M1. Overall, we propose that eye-hand coordination relies on similar predictive mechanisms for both hands, possibly located upstream of M1, which can be updated independently of hand movement control
Priot, Anne-Emmanuelle. "Composantes de l’adaptation à une altération des distances apparentes par modification de la demande en vergence." Thesis, Lyon 1, 2010. http://www.theses.fr/2010LYO10336/document.
There are numerous situations in which sensorimotor coordination is altered (e.g., growth, pathology, optical or mechanical interfaces). In such situations, the nervous system must adapt so that the organism continues to interact successfully with the environment. While visuomotor adaptation to visual direction alteration by lateral prisms has been widely studied, the mechanisms underlying visuomotor adaptation to alteration of apparent distance remain poorly known. We performed a series of psychophysical studies to explore the various components of adaptation to alteration of apparent distance. Base-out prisms were used to alter apparent distance by modifying vergence demand. By manipulating visual feedback, we were able to demonstrate three adaptation levels. The first level corresponds to changes in perceived distance related to tonic vergence. These changes result from eye muscle potentiation (EMP) induced by sustained vergence. The second level involves a recalibration of the altered distance signal derived from vergence by limb proprioceptive-motor signals. The third level results from a reorganization of motor commands of the upper limb used. No limb proprioceptive component was identified. The nature of adaptive components to apparent distance alteration differs from that described for visual direction alteration, which involves essentially proprioceptive and motor components. This difference can be attributed to differences in accuracy between proprioception and vision for localization in depth or in lateral directions. The geometrical aspects of distance perception based on vergence were also explored by comparing visual adaptation to base-out prisms (introducing an offset in vergence demand) and to a telestereoscope (multiplying vergence demand for all fixation distances). Regardless of which optic device was used, the recalibration of the relationship between the vergence signal and perceived distance consisted in a constant bias over distances
Hoffart, Louis. "Etude de la dynamique des conséquences fonctionnelles périphériques et centrales de lésions oculaires focales." Thesis, Aix-Marseille 2, 2010. http://www.theses.fr/2010AIX20671/document.
The brain shows a high ability to reorganize following alteration of sensorial input that may result from modification of the environment or disease of sensorial organs. Modern functional imagery techniques allow to examine the impact on the visual system of such alterations. The aim of this thesis was to develop new approaches for studying at the cortical level, functional consequences of ocular disease associated with a significant visual scotoma. In the first section of this thesis, we used high-field (3T) functional magnetic resonance imaging (fMRI) to study the cortical functional architecture. Our goal was to map the retinotopic organization of human early visual cortical areas (V1, V2, V3). By this method, we identified modifications of retinotopic organization induced by a focal loss of retinal stimulation (artificial scotoma) and we observed the cortical projections of artificial scotoma on healthy subjects by the mean of a specific stimulus. In the following part of the experimentation, this protocol was used on a patient who showed a maculopathy at the acute stage and after recovery. This study confirms the ability to evaluate the cortical representation (size and location) of a focalized modification of the retinal sensibility threshold and could serve as a basis for the future investigation of cortical plasticity in the visual cortex following retinal diseases. The second section of this thesis was directed to the development of optical imaging intrinsic signals on small animals. Our goals were to characterize the retinotopic organization of rat’s visual cortex. With this method, we will investigate the kinetics of cortical remapping and modifications of the neuronal activity level following retinal lesion. These results will be compared to the data previously acquired by fMRI in humans. Another application of our method will be to study the functional impact of retinal prosthesis. Ocular lesions are associated with local modifications of retinal tissue, and especially with neovascular ingrowth, for which functional consequences have not been totally clarified. We therefore developed models of peripheral lesions, which allow to study the effect of scotoma on retinotopic organization of primary visual cortex after peripheral sensory lesion. This thesis gives some new directions in the functional exploration in retinal disease as Age Related Macular Degeneration (ARMD)
Woog, Kelly. "Étude quantitative des cônes de la rétine imagés par optique adaptative : structure et lien avec la fonction visuelle." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS158.
The high-resolved imagery delivered by the adaptive optic is used to form pictures of the retina at the cellular level and to diagnose and follow up on eyes pathologies, but also to improve knowledge of the anatomy, functions and mechanisms of the retina.First we defined the method that allows us to position the center of the fovea and to measure the density of the cones with the best repeatability. The center of the ellipse of higher densities makes it possible to position the center of the fovea. The cone density is measured in a region of interest of 80 x 80 pixels to an eccentricity measured on a montage established from pictures made every 2°.One of the fundamental aspects of this project is the creation of a normative clinical database linked to bio-markers (density, spacing and morphology of cones). Indeed it is necessary to provide quantitative measures of the structures visualized. This study made it possible to characterize the retinal structure of a healthy population with no retinal disease, so as to establish a reference of normality. This study also allowed us to answer questions left unanswered by the literature. The density of the cones differs sharply between the horizontal and vertical meridians. We have also observed that the axial length influences cone density expressed in metric unit but not in terms of visual angle, supporting the hypothesis that the retina is stretched with the lengthening of the eyeball. Finally, age does not seem to have an impact on cone density except at 2°.We then examined the relationship between peripheral visual acuity and cone spacing. It is known that midget ganglion cells are in charge of visual resolution. But, at the fovea, each cone connects, via bipolar cells, to a midget ganglion cell ON and OFF. This anatomical particularity makes the measurement of the cone spacing an observable substitute for ganglion cells thus allowing the link with visual acuity. We have therefore determined to what eccentricity the cones are no longer an observable substitute for ganglion cells. We found that visual acuity is governed by the arrangement of cones up to 2° of eccentricity, both in nasal and inferior retinas, supporting the idea that only 50% of foveal mRGCs determine VA (mRGC ON or OFF). Beyond this, cone spacing over-samples ganglion cells. Watson developed a model to predict visual acuity based on the mRGC spacing, itself derived from the cone spacing. The 50% model (mRGC ON or OFF) also predicts visual acuity in the inferior meridian at 4° and 6° of eccentricity. Along the nasal meridian, the 50% model underestimates visual acuity. Partial overlap of the mRGC ON + OFF receptive fields may be the cause.Finally, we measured the cone density in the central 48° along the horizontal meridian in two study groups, one with a history of myopic evolution (i.e. elongation of the eye) and the other without. To this date, there is only one study with in-vivo measurements of cone density beyond the central 15°. This study also allowed us to assert that during myopic evolution, the retina stretches uniformly in the measured area, excepted near the optic nerve head, where it appears that there is a stronger adhesion
Bernier, Pierre-Michel. "Intégration des informations visuelles et proprioceptives dans la planification de mouvements finalisés : approches comportementales et électrophysiologiques." Aix-Marseille 2, 2009. http://www.theses.fr/2009AIX22002.
The objective of this thesis is to investigate: i) the influence of target modality (visual, proprioceptive) on the integrative processes associated with sensorimotor transformations, and ii) the integration of visual and proprioceptive hand signals during visuomotor adaptation. In the first experiment, we tested whether common sensorimotor transformations underlie the planning of reaching movements directed toward visual and proprioceptive targets. To do so, we used a prismatic adaptation paradigm to modify the visuomotor relationship. The aftereffects observed for movements directed toward visual targets did not generalize to movements directed toward proprioceptive targets. In the second experiment, we used electroencephalography to characterize the spatio-temporal dynamics of neural activity associated with the planning of reaching movements directed toward visual and proprioceptive targets. We found significant activation over parietal, premotor and sensorimotor scalp sites for both types of movements. However, notable differences were observed in the timing of these activations. In the third experiment, we provided evidence for a temporary suppression of the transmission of somatosensory afferents during exposure to a novel visuomotor relationship. Together, these results demonstrate that the integration of hand and target sensory signals is specific to the sensory modality of the target. They also highlight the functional flexibility with which visual and proprioceptive hand signals are integrated to optimise performance during visuomotor adaptation
Rouger, Hélène. "Validation de la prédiction de l'effet des aberrations sur les performances visuelles." Paris 11, 2009. http://www.theses.fr/2009PA112312.
The aim of this thesis consisted on validating the calculation of the impact of aberrations on visual performances (VP). We tested the ability of a numerical eye model to predict the influence of different aberrations conditions. We succeded in predicting (R²=0. 79) the contrast sensitivity (CS) visual benefit measured after higher-order aberrations correction by an adaptive optics system, using the modulation transfer function (MTF) derived from a wavefront aberration measurement. However, the visual acuity (VA) benefit was not well predicted (R²≤0. 30) by the calculated image quality metrics. We also succeded in predicting CS losses (R²≥0. 75) and VA losses (R²≥0. 74) due to different types and levels of aberrations in calculating respectively the MTF and several image quality metrics. We also predicted the impact of aberrations combinations (multifocal contact lenses) on through-focus CS (R²=0. 74) and through-focus VA (R²=0. 67). Adaptation phenomenons to the multifocal contact lenses aberrations could explain the larger calculated VA losses. We studied this hypothetical neural adaptation in comparing the keratoconic subjects VP when viewing through their usual spectacles correction and the normal subjects VP when viewing through keratoconic subjects aberrations. Keratoconic subjects obtained comparable CS but higher VA than normal subjects (0. 13logMAR), validating a possible increase of VA by adaptation. So, the tested numerical eye model is able to predict the CS changes. The VA changes are more difficult to predict because of neural adaptation
Marais, Michaël. "Adaptation cardiovasculaire aux vols spatiaux : interaction des stimulations otolithiques et visuelles avec le contrôle baroréflexe de la circulation chez l'homme." Caen, 2011. http://www.theses.fr/2011CAEN3048.
Baroreflex loops are the main effectors of the cardiovascular short-term regulation. However, numerous studies have shown that the otolithic system was able to modify the activity of the sympathetic nervous system to induce changes in peripheral vasomotricity in humans. Our hypothesis is that regulation of the cardiovascular system would use a system that integrates different neurosensory afferents with barosensitive afferents to regulate blood pressure. To update this complex system of regulation, we have demonstrated in these works that visual afferents may induce cardiovascular changes (in presence and absence of otolithic afferents). Furthermore, our studies during a prolonged bed rest protocol allowed us to identify alterations in cardiovascular responses induced by otolithic and visual stimuli. We can therefore conclude that otolithic and visual systems involved most likely in cardiovascular deconditioning. This is reflected, among other things, orthostatic intolerance and decreased sensitivity of carotid baroreflex. Our results demonstrate that otolithic afferents have an inhibitory effect on the response of cardiac and vascular carotid baroreflex in the supine position. Thus, all our results demonstrate that visual and otolithic afferents are integrated with barosensitive afferents to ensure proper regulation of the cardiovascular system
Jobert, Marc. "Filtrage adapté : application à l'étude des potentiels évoqués visuels et à la détection des signaux caractéristiques du stade 2 de l'EEG du sommeil." Compiègne, 1989. http://www.theses.fr/1989COMPD283.
Carrière, Véronique. "Apprentissage médié par les TICE : le cas des étudiants déficients visuels." Phd thesis, Université Paul Valéry - Montpellier III, 2012. http://tel.archives-ouvertes.fr/tel-00718602.
Burger, Brice. "Fusion de données audio-visuelles pour l'interaction homme-robot." Phd thesis, Toulouse 3, 2010. http://thesesups.ups-tlse.fr/916/.
In the framework of assistance robotics, this PHD aims at merging two channels of information (visual and aiditive potentially avaible on a robot. The goal is ton complete and/ or conf rm data that an only channel could have supplied in order to perform advanced intatraction which goal is to interpret jointly speech gesture, in particular for the use of spatial references. In this thesis, we first de cribe the speech part of this work which consists in an embedded recognition and interpretation system for continuous speech. Then comes the vision part which is composed of a visual multi-target tracker that tracks, in 3D the head and the two hands of a human in front of the robot, and a second tracker for the head orientation. The outputs of these trackers are used to feed the gesture recognitive system described later. We continue with the description of a module dedicated to the fusion of the data outputs of these information sources in a probailistic framework. Last, we demonstrate the interest and feasibility of such a multimodal interface through some demonstrations on the LAAS-CNRS robots. All the modules described in this thesis are working in quasi-real time on these real robotic platforms
Le, Bras Florent. "Contributions à l'asservissement visuel de véhicules aériens autonomes." Nice, 2010. http://www.theses.fr/2010NICE4110.
The visual servo control technology is based on measurements form a camera. This technique appeared in the late 80’s to control mobile robots or manipulators. Recently, visual servoing is applied to flying vehicles, for which this type of control has a strong operational potential. In this thesis, we focus on the design of visual servoing for two types of flying vectors : the VTOL minidrones and fixed-wing aircrafts. We try wherever possible to specify the problem in terms of regulation in the picture by taking into account the limitations of the sensors used. Thus we consider only the onboard sensors autonomous, and whose quality is consistent with a the considered visual servoing tasks. For this, we propose visual servoing laws adapted to the considered systems intheir control structures and their measurement systems. For VTOL minidrones, a series of control laws is proposed to stabilize the vehicle with respect to a relativity flat target which some landmarks are detected in real time. These commands have the distinction of not requiring measurements of the speed of translation. This characteristic is especially interesting, since this variable is particularly difficult to measure without GPS. One of the algorithms has been, validated in fight ion the platform. HoverEye developed by Bertin Technologies, it was, to our knowledge the first image based visual servoing, conducted indoors on a minidrones. For fixed-wing aircrafts, a next autonomous landing technique based on the detection of runway’s edges is proposed. This technique is image based and takes into account the specificities of aircraft flight dynamics. Moreover a specific estimate of cross-wind is proposed. Validation of this approach is performed on a complex simulator which includes images processing. Finally, we sought new applications in image based visual servoing for fixed-wing aircrafts. A control law for precise stabilization on observation orbit has been synthesized. It is based on the detection of a single landmark and translational optical flow. Simulations illustrate the performance of that algorithm
Bara, Blaise. "Procédure automatisée et stratégie adaptative pour le dépistage des déficits du champ visuel." Lille 1, 1986. http://www.theses.fr/1986LIL10152.
Bara, Blaise. "Procédure automatisée et stratégie adaptative pour le dépistage des déficits du champ visuel." Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb375956974.
Tornil, Bertrand. "Adaptations et interactions gestuelles et haptiques, ciblées utilisateurs : vers plus d'utilisabilité et d'accessibilité." Toulouse 3, 2006. http://www.theses.fr/2006TOU30240.
In this thesis, we focused on force feedback technologies, and its applications in interactive systems. Tactilo-kinesthetic or “haptic” system is the mix of moves and tactile/kinesthetic perceptions. First, we used a force feedback device in order to try to reduce times in a point and click task. The experiment proves that force feedback may cause a distractor for the user, by rising times by 25%. Nest, we show that this situation can be better with a variable intensity force. Next, we defined the “relative localization” concept, where the mental image can be rebuild only with haptic and audio stimuli, without visual cues. Lastly, we developped prototypes applying the relatice localization, for geography, anatomy and musical applications
Derviaux, Christian. "Evaluation de la visibilité des effets de blocs dans le codage MPEG : application à l'amélioration de la qualité visuelle de séquences video." Valenciennes, 1998. http://www.theses.fr/1998VALE0032.
Carriere, Véronique. "Apprentissage médié par les TICE : le cas des étudiants déficients visuels." Phd thesis, Université Paul Valéry - Montpellier III, 2012. http://tel.archives-ouvertes.fr/tel-00718447.
Chriette, Abdelhamid. "Contribution à la commande et à la modélisation des hélicoptères : asservissement visuel et commande adaptative." Evry-Val d'Essonne, 2001. http://www.theses.fr/2001EVRY0013.
Burger, Brice. "Fusion de données audio-visuelles pour l'interaction Homme-Robot." Phd thesis, Université Paul Sabatier - Toulouse III, 2010. http://tel.archives-ouvertes.fr/tel-00494382.
Buessler, Jean-Luc. "Architectures neuro-mimétiques modulaires : application à l'asservissement visuel de systèmes robotiques." Mulhouse, 1999. http://www.theses.fr/1999MULH0587.
Levy, Manuel. "From boxes to codes : adaptation of V1 nonlinearities to the temporal encoding of spatial information during simuled eye movements." Paris 6, 2007. http://www.theses.fr/2007PA066238.
This thesis focuses on the processing and temporal encoding of natural stimuli by simple cells of the primary visual cortex (V1). Neuronal responses were recorded by intra- and extra-cellular electrodes in the anaesthetized and paralysed Cat, and analysed with tools derived from system identification and information theory. We show that the recruitment of contrast gain controls and centre surround interactions, in particular by stimuli having natural eye movement dynamics, increases the reproducibility of the high temporal frequencies components of the membrane potential, as well as the temporal precision and sparseness of the spike output. The addition of a complex-like, feedforward, delayed inhibition to the classical LN model accounted largely for our results. Finally we propose that V1 nonlinearities are adapted to the coarse-to-fine processing and temporal encoding of spatial information during the course of an ocular fixation
Rougier, Nicolas P. "Fondements biologiques pour le calcul distribué, numérique et adaptatif." Habilitation à diriger des recherches, Université Nancy II, 2011. http://tel.archives-ouvertes.fr/tel-00596740.
Colliaux, David. "Classes de dynamiques neuronales et correlations structurées par l'experience dans le cortex visuel." Phd thesis, Ecole Polytechnique X, 2011. http://pastel.archives-ouvertes.fr/pastel-00676104.
Kime, Sihem. "From adaptation mechanisms with visual impairment to new technologies in vision restoration." Electronic Thesis or Diss., Paris 6, 2016. http://www.theses.fr/2016PA066750.
Visual impairment is a condition, which can lead to blindness, and has an enormous impact on the quality of life of the affected individuals, and in assistance costs for the whole society. An important research effort is therefore spent in developing novel technologies, aiming to restore visual functionality. Currently the most promising technology is represented by retinal implants, with two companies producing devices approved for commercialization. The first clinical studies encouragingly reported perception elicited by both devices. Some patients retrieve autonomy, but only a few could reach satisfactory perception levels, allowing more complex tasks such as reading. Hence limitations exist in both spatial and temporal resolution, and these limitations call for improvements of the technology and of the stimulation strategies used therein. The focus of this thesis lies in presenting possible modalities to improve the perception quality provided by implants. An original study on RP patients, which is the principal population targeted by retinal implants, presents visual adaptation strategies developed after losing peripheral vision. The second part of the thesis presents a platform projecting at high frame rates, and evaluates its impact on visual performances. The last contribution of the work hereby presented is on the impact of high frame rate projection on visual restoration technologies. This study allowed to accurately replicate the perceptual effects of the technologies studied, and to evaluate potential performance improvements using higher temporal resolutions for stimulation strategies in visual restoration devices
Wira, Patrice. "Réseaux neuromimétiques, modularité et statistiques : estimation du mouvement pour l'asservissement visuel de robots." Phd thesis, Université de Haute Alsace - Mulhouse, 2002. http://tel.archives-ouvertes.fr/tel-00009211.
Nous nous sommes intéressé au cas d'objets mobiles, et plus particulièrement à l'estimation du mouvement de ces objets, nécessaire pour une exécution satisfaisante des tâches de poursuite. La qualité de poursuite est en effet grandement améliorée grâce à une estimation robuste du mouvement. Pour réaliser l'estimation, nous proposons une approche nouvelle, basée sur l'aspect adaptatif du filtrage de Kalman. Contrairement au filtre classique de Kalman, ce filtre n'utilise aucun modèle ni connaissance a priori. La représentation d'état est adaptée en permanence en fonction des observations courantes pour représenter au mieux la dynamique du système. Il s'agit d'une approche modulaire à modèle multiple. Plusieurs filtres sont utilisés et la probabilité pour chacun de calculer l'estimation optimale est déterminée par apprentissage. Un réseau de neurones, sur cette base statistique, supervise l'ensemble des filtres et permet de compenser le caractère non stationnaire des mouvements de l'objet mobile.
Les informations visuelles estimées servent à contrôler les déplacements du robot. Des extensions de la carte auto-organisatrice de Kohonen à sorties supervisées servent à approximer la transformation sensori-motrice du système robot-vision. La relation apprise se trouve dès lors à l'origine de la loi de commande du robot. L'apprentissage est entièrement réalisé en contexte, en exploitant les corrélations sensori-motrices durant les mouvements des robots.
Les méthodes présentées dans cette thèse ont été validées en simulation et par des expérimentations réalisées sur une plate-forme robotique réelle.
Netto, Mariana Schiavo. "La commande adaptative de systèmes non-linéairement paramétrés." Paris 11, 2001. http://www.theses.fr/2001PA112320.
The contents of the thesis are divided into three main parts as follows. The first part treats the visual servoing problem, consisting of the control of the motion of a two-links planar robot manipulator by a fixed TV camera. We propose two different solutions to solve the problem. The second main part is devoted to the study of the use of the convexity property in the adaptive control of nonlinearly parametrized plants. We first treat a class of plants considered by Boskovic. We propose a reparametrization that convexifies the nonlinearity. We then apply a known controller to the convexly-parametrized system. We provide then a comparison between the controller applied to the reparametrized plant and the controller by Boskovic. The next step was to extend this convexifying reparametrization to a more general class of nonlinear parametrizations. This new result is used for the adaptative control of fed-batch fermentation processes. .
Kermorgant, Olivier. "Fusion d'informations multi-capteurs en asservissement visuel." Phd thesis, Université Rennes 1, 2011. http://tel.archives-ouvertes.fr/tel-00747052.