Dissertations / Theses on the topic 'Imagerie neuronale'
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Nadeau, Gabriel. "Imagerie optique de la plasticité synaptique." Master's thesis, Université Laval, 2016. http://hdl.handle.net/20.500.11794/27375.
Full textClassical measurements of synaptic plasticity have involved electrophysiological methods which provide high sensitivity for detecting small changes in synaptic strength. However, this approach does not provide much information about the location of the synapses that undergo plastic changes. Because synaptic plasticity can be synapse-specific, having the ability to monitor changes in synaptic strength at individual synapses is important in order to enable simultaneously monitoring of local molecular mechanisms associated with the plasticity. New fluorescent tools developed in the last decades allow to directly visualize synaptic activity, signaling, and remodeling at individual synapses. During my Master studies, I used optical imaging of a genetically-encoded calcium (Ca2+) sensor, GCaMP6f, to record miniature synaptic Ca2+ transients (MSCTs) in cultured rat hippocampal neurons. For these experiments, I performed video-microscopy on neurons perfused with external solution lacking Mg2+ and containing Tetrodotoxin (0Mg2+/TTX). I have observed highly localized and transient increases of intracellular Ca2+ in dendritic compartments and spines. To test whether these MSCTs can be potentiated, I have measured them before and after a 5 min stimulation known to induce plasticity in cultured neurons (0Mg2+/Glycine/Bicuculline, cLTP). A lasting increase in the frequency and amplitude of MSCTs, for at least an hour, arose from this stimulation protocol. I have thus investigated the molecular mechanisms of this plasticity. The MSCTs are mostly mediated by NMDA receptors, since they are almost totally blocked by the selective antagonist to the receptor, AP5. Moreover, addition of AP5 only during the cLTP stimulation blocks the MSCT plasticity. It thus appears that both the MSCTs and their plasticity are NMDA receptor-dependent. Interestingly, the MSCTs and their plasticity are not blocked by the AMPA receptor antagonists NBQX, pointing to possible changes in NMDA receptor content, postsynaptic Ca2+ signaling, or presynaptic neurotransmitter release. Also, while we found that CaMKII signaling is non-essential for the induction of the plasticity, preliminary data are showing a plausible PKA-dependency of the plasticity. To test these hypotheses, I have also tried to combine Ca2+ imaging with imaging of other pre and postsynaptic components, to identify the molecular mechanisms responsible for the MSCT plasticity. Overall, this new approach presented in this thesis might provide new knowledge on the diversity of molecular processes that support synaptic potentiation.
Parpaleix, Alexandre. "Imagerie biphotonique de la Po2 intracérébrale : une mesure de l’activité neuronale." Thesis, Paris 5, 2013. http://www.theses.fr/2013PA05T072/document.
Full textIn humans, functional mapping of brain activity mainly relies on the increase of cerebral blood flow (CBF) triggered by neuronal activation. This neurovascular coupling provides energy substrates such as oxygen and glucose to the activated area. The steady state concentration of oxygen, as well as its dynamics upon neuronal activation, have been investigated with numerous methods, however, none of them provided highly resolute measurements in depth. During my PhD, we combined a phosphorescence quenching approach with two-photon microscopy to detect, in depth and with a micrometer spatial resolution scale, the emission of phosphorescence by PtP-C343, a new oxygen nano-sensor designed for two-photon excitation. We first characterized the technique and then reported two biological results, using the olfactory bulb (OB) glomerulus as a model to study oxygen concentration, at rest and upon odor stimulation. We found an arterio-venous shunt, purely based on diffusion, in the superficial nerve layer of the OB, confirming the role of arterioles in brain oxygenation. Simultaneous measurements of Po2 and blood flow allowed us to reveal the presence of erythrocyte-associated transients (EATs), i.e. Po2 fluctuations that are associated with individual erythrocytes. Pursuing the investigation of EAT characteristics, we found that in capillaries, Po2 at mid-distance between two erythrocytes is at equilibrium with, and thus reports Po2 in the nearby neuropil. Finally, we could observe that even in capillaries, a small oxygen initial dip can be detected prior to functional hyperemia, upon odor activation
Dupont-Therrien, Olivier. "Développement d'outils pour l'imagerie de l'activité neuronale - des épines au comportement." Doctoral thesis, Université Laval, 2017. http://hdl.handle.net/20.500.11794/27491.
Full textDue to the scale of the observed structures and behaviours, neurosciences and microscopy have always been intertwined. Whether it is to observe the different cell morphologies in transmitted white light, or to follow complex dynamics using fluorescent probes, light is the tool of choice to study the brain and its composition. Specifically, the light has the proper spatial and temporal resolution to probe both locally and globally all levels of neuronal activity, while remaining minimally invasive. This thesis shows three techniques developed for different scales, in order to push the limits of the currently addressable biological questions by neuroscientists. In order to effectively probe the internal mechanisms for small structures like dendritic spines and dendrites, we have created a single-cell labeling protocol of the voltage-sensitive fluorophore ANNINE-6plus. The method is based on the intracellular loading of the fluorescent probe in samples both in dissociated cell cultures, than in preparations of acute and organotypic slices. The second project addresses the challenges of rapid imaging of the cellular network activity. Typically, there is a choice between the temporal resolution and the imaging surface. This choice is that the fast imaging techniques are usually widefield and do not provide optical sectioning, making their use in thick samples difficult. By combining a widefield multiphoton technique, the temporal focusing, with the structured illumination and an amplified laser, we have developed a widefield system with an optical sectioning below 10um. The third chapter describes the development of two software distributed with a product created by Doric Lenses Inc., an implantable miniature microscope for imaging of deep brain structures of freely moving animals. This product finally provides a link between the local neuronal activity, and the observed animal behaviours.
Radecki, Guillaume. "Imagerie cellulaire par résonance magnétique rehaussée au manganèse (CelMEMRI)." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112212/document.
Full textScience has evolved since the 19th century. New tools have appeared such as optical microscopy which gives us the vision of cells and electronic microscopy which leads us into their hearts. The magnetic resonance imaging appeared in the seventies. Evolving over time, the MRI has taken us farther and farther into the secret depths of our brains. The possibility of observing the neuronal activity thanks to the functional imaging is a major evolution. This thesis will show the possibility we have to observe the activity of a single neuron without modification of its network thanks to the manganese enhanced magnetic resonance imaging technique. The study was done on the Aplysia at very high field magnet (17T). These animals are marine gastropod mollusks with a peculiarity: their neurons are of important size and can reach 1 mm in diameter. Their neurons are grouped into several ganglia. My study concerns the buccal ganglion which is the most studied ganglia in the research in electrophysiology. Before making any acquisitions, I had to conceive several microscopic coils adapted to the size of the ganglions. By reducing the size of the coils, the signal of the noise ratio increases. Then, a double coil allowing the simultaneous acquisition of two samples was built. This antenna required the construction of pre-amplifiers operating at 730 MHz. The first series of experiments helped observe the evolution of the neuronal activity according to different stimuli linked to the eating habits of the Aplysia in vivo. Thanks to the technique implemented, I shall show that, using MRI, it is possible to distinguish the activity of each neuron with respect to a stimulus. Afterwards, to continue this work, a second series of experiments was made in vitro. I studied the behavior of neurons when perfused with neural stimulators: dopamine and serotonin, both naturally present in the Aplysia. Generally, all neurons were activated but when observing them individually, I noticed some differences. Studies in electrophysiology will allow us to get a better understanding and a confirmation of the results of this study. The MEMRI technique can be used in the future to study various disorders such as compulsive behaviors, which are present in the Aplysia, and probably have the same origins as in humans, given that many fundamental processes (such as memory studied by Eric Kandel who he demonstrated that human and Aplysia memories works with the same mechanism) are similar between the two species
LOISEL, DIDIER. "Imagerie des anomalies de la gyration et de la migration neuronale chez l'enfant." Angers, 1994. http://www.theses.fr/1994ANGE1077.
Full textBosque-Freeman, Léorah. "Imagerie de la dégénérescence neuronale dans une maladie démyélinisante : la sclérose en plaques." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066522/document.
Full textMultiple sclerosis (MS) has long been regarded as an inflammatory demyelinating disorder of the white matter. But post-mortem studies have recently shed light on the extensive involvement of the grey matter (GM). Neuronal damage, characterized by synaptic and dendritic loss as well as neuronal apoptosis, is thought to be a major substrate of physical and cognitive deterioration in MS patients. There is a crucial need for new imaging techniques able to specifically assess neuronal damage in MS. Using positron emission tomography (PET) with [11C]flumazenil ([11C]FMZ), an antagonist of the central benzodiazepine site located within the GABAA receptor, and a non-invasive quantification method, we measured and mapped neurodegenerative changes in the GM of patients with MS at distinct disease stages. A cohort of 18 MS patients was compared to 8 healthy controls and underwent neurological and cognitive evaluations, high-resolution dynamic [11C]FMZ PET imaging and brain MRI. PET data were evaluated using a region of interest and a surface-based approach. [11C]FMZ binding was significantly decreased in the cortical and subcortical GM of MS patients compared to controls. These changes were significant in both progressive and relapsing-remitting forms of the disease and correlated moderately with white matter lesion load. [11C]FMZ cortical binding was also associated with cognitive performance. This pilot study is the first to quantify in vivo the neurodegenerative changes occurring in MS. Our results show that PET with [11C]FMZ could be a promising and sensitive quantitative marker to assess and map the neuronal substrate of GM pathology in MS
Jung, Mathieu. "Évaluation univariante de la qualité des images par une approche neuronale." Toulouse, ENSAE, 2000. http://www.theses.fr/2000ESAE0012.
Full textLeclerc, Gabriel. "Apprendre de données positives et non étiquetées : application à la segmentation et la détection d'évènements calciques." Master's thesis, Université Laval, 2021. http://hdl.handle.net/20.500.11794/69813.
Full textTwo types of neurotransmission occur in brain’s neurons: evoked transmission and spontaneous transmission. Unlike the former, the role of spontaneous transmission on synaptic plasticity –a mechanism used to endow the brain learning and memory abilities – remain unclear. Spontaneous neurotransmissions are localized and randomly happening in neuron’s synapses. When such spontaneous events happen, so-called miniature synaptic Ca²⁺ transients(mSCT), second messenger calcium ions entered the spine, activating downstream signaling pathways of synaptic plasticity. Using calcium imaging of in vitro neuron enable spatiotemporal visual-ization of the entry of calcium ions. Resulting calcium videos enable quantitative study of mSCT’s impact on synaptic plasticity. However, mSCT localization in calcium imaging can be challenging due to their small size, their low intensity compared with the imaging noise and their inherent randomness. In this master’s thesis, we present a method for quantitative high-through put analysis of calcium imaging videos that limits the variability induced by human interventions to obtain evidence for characterizing the impact of mSCTs on synaptic plasticity. Based on a semi-automatic intensity thresholded detection (ITD) tool, we are able to generate data to train a fully convolutional neural network (FCN) to rapidly and automaticaly detect mSCT from calcium videos. Using ITD noisy segmentations as training data combine with a positive and unlabeled (PU) training schema, we leveraged FCN performances and could even detect previously undetected low instensity mSCTs missed by ITD. The FCN also provide better segmentation than ITD. We then characterized the impact of PU parameters such as the number of P and the ratio P:U. The trained FCN is bundled in a all-in-one pipeline to permit a high-thoughtput analysis of mSCT. The pipeline offers detection, segmentation,characterization and visualization of mSCTs as well as a software solution to manage multiple videos with different metadatas.
Panier, Thomas. "Imagerie par nappe laser de l'activité neuronale dans l'ensemble du cerveau d'un poisson-zèbre." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2014. http://tel.archives-ouvertes.fr/tel-00979762.
Full textFeydy, Antoine. "Plasticité cérébrale et récupération motrice après un accident vasculaire cérébral ischémique : étude en imagerie par résonance magnétique fonctionnelle (IRMf)." Paris 13, 2002. http://www.theses.fr/2002PA132018.
Full textBreton, Stéphane. "Une approche neuronale du contrôle robotique utilisant la vision binoculaire par reconstruction tridimensionnelle." Mulhouse, 1999. http://www.theses.fr/1999MULH0532.
Full textLê, 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.
Full textThrough 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
Lambert, Séverine. "Modèle du mind's hand : contribution anatomo-fonctionnelle et comportementale à l'étude du lien entre l'image mentale et la perception dans le handicap visuel." Lyon 1, 2003. http://www.theses.fr/2003LYO1T174.
Full textDinomais, Mickaël. "Etude du cortex sensori-moteur en imagerie par Résonance Magnétique Fonctionnelle : du sujet sain à l'enfant avec paralysie cérébrale." Angers, 2013. http://tel.archives-ouvertes.fr/tel-01021084.
Full textCerebral palsy (CP) is a non-progressive injury to the developing central nervous system resulting in permanent disorders of the development of movement and posture, causing activity limitation. Therefore physical and rehabilitation medicine has a particular interest in the study of organization and reorganization of the sensorimotor cortex following early brain injury in order to propose new methods for motor rehabilitation. We first showed that motor cortex could be analyzed in functional magnetic resonance imaging (fMRI) using action-observation and passive movement tasks. We then demonstrated in patients with unilateral CP that resting state analysis could study functional connectivity in sensorimotor system. Moreover, our work showed that observing hand movement produced, in CP patients, large bilateral activations in temporo-parieto-fronto-occipital network, comprising most of the nodes of the well described action-observation network. For either side, observing hand movements recruits the primary motor cortex, contralateral to the viewed hand, as would be expected in healthy persons. In addition, we showed that the combination of observation of congruent hand movement simultaneously to passive movement of the paretic hand recruits more motor areas, giving neuronal substrate to propose video-guided passive movement of paretic hand in CP rehabilitation. Finally we present the perinatal stroke as a well suited model to analyze the postlesional neural plasticity notably the "mal-adaptive" plasticity
Roux, Franck-Emmanuel. "Validation du signal de l'IRM fonctionnelle motrice par la stimulation corticale chez les patients atteints de tumeurs cérébrales." Paris 11, 2002. http://www.theses.fr/2002PA11T017.
Full textCoget, Arthur. "Etude et modélisation de la plasticité cérébrale chez des patients porteurs de lésions gliales de bas grade opérés en chirurgie éveillée." Thesis, Montpellier, 2020. http://www.theses.fr/2020MONTS053.
Full textIntroductionDiffuse low-grade gliomas (DLGG) are slow-growing brain tumors occurring in young adults. This slow progression induces extensive neuroplasticity and explains why patients most of the time do not show any obvious neurological deficit at the time of diagnosis although tumors are located in ‘eloquent’ areas. Therefore DLGG provide an interesting model in understanding mechanisms of neuroplasticity.Awake surgery with direct cortical and subcortical electrostimulation mapping is recommended as first-line treatment of DLGG, allowing to maximize tumoral resection and limiting postoperative neurological deficit, maintaining patients quality of life.Resting-state fMRI, based on BOLD signal analysis, is used to study functional connectivity and neural plasticity. This technique allows robust evaluation of neural networks without performing a task. Consequently, it bypasses the impact of confusion, sedation or neurological deficits on task execution. In this thesis, we aimed to investigate perioperative functional connectivity modifications in order to evaluate neural plasticity after awake surgery.Subsequently we explained the functional results using multimodal MRI imaging to analyze anatomic connectivity and hemodynamic parameters.Methods82 patients with DLGG who underwent awake surgical resection were included in the principal study. MRI acquisitions were performed successively before, within 36 h after and three months post-surgery. All scans were executed on the same MRI magnet for each patient, i.e. either a 3.0 T magnet (Skyra, Siemens) or a 1.5 T magnet (Avanto, Siemens). First, data were preprossed using a standardized classical pipeline and analyzed with the CONN toolbox v16.a.Second, anatomic connectivity was evaluated using diffusion tensor imaging of the corpus callosum.Finally hemodynamic changes induced by surgery were assessed with traditional perfusion imaging as well as using an innovative analysis of the BOLD signal’ s temporal shift.ResultsSurprisingly, it was found that specifically a diffuse transient postoperative interhemispheric disconnectivity occurred between homologous regions, known as homotopic connectivity.In parallel, immediate and long-term postoperative alterations in the anatomic connectivity of the corpus callosum were observed. Immediate and long-term postoperative modifications were also found regarding both regional and global hemodynamics characteristics. Yet, no significant link between the homotopic connectivity findings and the anatomical and hemodynamic changes could have been established at this point.Nevertheless, the hemodynamic analysis allowed the identification of a a specific brain region : the striatum. It was hypothesized that it acts as a central region for the maintenance of homotopic connectivity, explaining simultaneously the decreased post-surgical homotopic connectivity observed.ConclusionThe highlighted transient postoperative functional homotopy is probably due to multifactorial causes To start entangling these causes, the use of anatomic and hemodynamic imaging data analyses seems crucial to interpret functional connectivity data both immediate and long-term postoperative.Cerebral vasoreactivity and modelling studies provide thereby a very promising tool to better understand the interrelated processes underlying postoperative functional connectivity modifications
Dubois-Murat, Patricia. "Phénotype neuropsychologique du syndrome de Turner : développement et apport du traitement intermodal visuel, verbal, auditif et haptique." Paris 8, 2008. http://octaviana.fr/document/137813864#?c=0&m=0&s=0&cv=0.
Full textTurner syndrome (TS) is a neurogenetic disorder affecting exclusively females. It is characterized by the complete or partial absence of one X chromosome. The clinical and experimental study presented here aims at analyzing the neuropsychological phenotype of Turner patients by focusing on the cross-modal processing in comparison with one-mode processing. The analysis is completed by intellectual efficiency, executive and visuospatial functions, emotional facial expression identification and of psychosocial aspects. We tested 12 eight to fifty year-old Turner subjects matched with 60 control subjects, using 28 tests most of which were computerized and timed. The results discussed in light of recent functional imaging data bring new information on the ST cognitive phenotype and refine our understanding of multimodal information integration processing to healthy subjects. We show two dissociations and the impairment of the verbal digit span in TS cognitive profile. The cross-modal processing is marked by a significant slowness selectively found in one-mode processing. However the cross-modal processing improves the reaction time of the TS subjects and their scores in certain areas. This report opens a way of reflection about cognitive remediation according to the neuronal plasticity
Dubois-Murat, Patricia Plaza Monique. "Phénotype neuropsychologique du syndrome de Turner développement et apport du traitement intermodal visuel, verbal, auditif et haptique /." Saint-Denis : Université de Paris 8, 2009. http://www.bu.univ-paris8.fr/web/collections/theses/DuboisMuratThese.pdf.
Full textJebara, Najate. "Organisation fonctionnelle de la perception des objets en vision centrale et en vision périphérique : sujets sains et pathologies ophtalmologiques." Lille 2, 2009. http://www.theses.fr/2009LIL2S011.
Full textRomand-Monnier, Margaux. "Functional and structural brain adaptations to changing and uncertain environments in humans." Thesis, Université de Paris (2019-....), 2019. http://www.theses.fr/2019UNIP7117.
Full textIn a world characterized by stochasticity, volatility and ambiguity, efficiently adapting to the environment uncertainty is absolutely crucial. Such adaptation takes place over a continuum of timescales; from the tens of milliseconds necessary for neurons to modulate firing rates, to the weeks allowing structural brain changes, to the millennia needed for the complex reorganization of the brain anatomy and function like the one observed in primate evolution. In this thesis, we tackle brain adaptations to uncertain and changing environments at two different timescales. First, we investigate the fast and short-term brain functional modulations allowing adaptive decision-making behaviour in response to sudden changes in the environment. In a two-armed bandit task comprising various levels of volatility, we show that a simple inference model assuming stable external contingencies but with computation imprecisions following the psychophysical Weber law, hereafter inference noise model, performs virtually as well as the optimal Bayesian adaptive process inferring the volatility of the environment. We also establish that this inference noise model better accounts for human behavioural performance in changing environments than the optimal Bayesian one. Using model-based fMRI analyses, we show that the anterior cingulate cortex (ACC) activations, previously associated with the volatility inferred from the optimal Bayesian model, rather reflect inference noise. Our results suggest that humans ability to adapt in a changing environment partly stem from Weber-structured inferential noise rather than from complex probabilistic inference of the environment volatility. In the second part of this work, we study how slow and long-lasting brain structural adaptations, also known as brain plasticity, go along with adaptive behaviour in new and uncertain environments at a scale of weeks. To investigate this issue, brain structural MRIs were obtained for a 44-year-old male subject, who left his regular life environment for four one-month expeditions in extremely challenging and harsh environmental conditions. Physical challenges stemmed from trekking in extreme temperatures and degrees of humidity. In addition, the subject faced great emotional and social challenges resulting from social deprivation, as he spent these expeditions in complete social isolation. Comparison of structural images before and after expeditions using voxel-based morphometry (VBM) analysis revealed significant changes of gray matter (GM) density in well-known regions involved in motor functions, perception, higher cognition and social cognition networks. This longitudinal case study findings show that brain structural adaptations go beyond the well-known and characterized plasticity associated with learning, by revealing brain changes in response to environmental demands, rather than task demands. This suggests that brain plasticity can happen when the environment over- or under-solicits specific functions, beyond the repetition of specific tasks. These findings are based on a single subject data, and future research should investigate whether this structural plasticity generalises to the population
Manent, Jean-Bernard. "Modulation de la migration neuronale par les neurotransmetteurs GABA et glutamate : aspects fondamentaux et implications pathologiques." Phd thesis, Université de la Méditerranée - Aix-Marseille II, 2006. http://tel.archives-ouvertes.fr/tel-00103505.
Full textDe nombreuses études ont identifié les neurotransmetteurs comme des molécules porteuses d'informations à un niveau plus large que celui de la seule transmission synaptique. En effet, avant même la formation de synapses, les neurotransmetteurs sont présents au sein du tissu cérébral embryonnaire et exercent des actions variées, influençant les étapes de genèse, migration, différentiation et de mort neuronale. Nous avons évalué les rôles joués par les neurotransmetteurs GABA et glutamate au cours de la migration neuronale, ainsi que les conséquences de la perturbation de leurs actions durant la construction du cerveau foetal.
Afin d'étudier la migration neuronale, nous avons mis au point des préparations originales permettant la visualisation directe de neurones fluorescents en migration. Grâce à elles, nous avons démontré l'existence d'une modulation de la migration neuronale par le GABA et glutamate, libérés selon un mode de sécrétion « non vésiculaire » et agissant par l'intermédiaire de récepteurs spécifiques. Nous avons montré que les mécanismes modulant la migration sont caractéristiques du type neuronal et du mode migratoire considéré. Ainsi, la migration radiale des futurs neurones glutamatergiques est modulée majoritairement par l'activation de récepteurs GABAA, alors que la migration tangentielle des futurs interneurones GABAergiques est modulée par l'activation de récepteurs glutamatergiques de type AMPA. Ces résultats suggèrent également l'existence d'une communication précoce entre neurones glutamatergiques et interneurones, pouvant contribuer à la construction cérébrale. Par la suite, nous avons évalué le risque de survenue de malformations cérébrales foetales, suite à l'administration de médicaments anti-épileptiques, qui potentialisent l'action du GABA, limitent l'action du glutamate et modulent l'activité des canaux ioniques. Nous avons observé une incidence accrue de micro-dysplasies cortico-hippocampiques, à rapprocher de défauts de migration, suite à l'administration chez la rate gestante de valproate et de vigabatrin à des doses compatibles avec celles employées pour le traitement de la femme enceinte épileptique.
Ces résultats soulignent le rôle central joué par les neurotransmetteurs GABA et glutamate, en tant que signaux informatifs majeurs du cerveau en développement. De plus, ils suggèrent le besoin d'évaluer l'impact de l'exposition à des composés pharmacologiques interférant avec les actions de ces neurotransmetteurs lors de la maturation cérébrale.
Jerbi, Karim. "Localisation de l'activité cérébrale et étude des oscillations et des synchronies à l'arge échelle en magnétoencéphalogie : le cas de l'intégration visuomotrice chez l'homme." Paris 6, 2006. http://www.theses.fr/2006PA066118.
Full textReuter, Françoise. "Perturbations cognitives au stade initial de la sclérose en plaques : Corrélats structuraux et application d'un modèle d'accès à la conscience." Aix-Marseille 2, 2008. http://www.theses.fr/2008AIX20698.
Full textAubert, Agnès. "Imagerie fonctionnelle cérébrale et modélisation mathématique de la relation entre activité neuronale, métabolisme énergétique et hémodynamique : application à l'imagerie des gliomes de bas grade." Paris 6, 2003. http://www.theses.fr/2003PA066353.
Full textKubler, Samuel. "Statistical methods for the robust extraction of objects’ spatio-temporal relations in bioimaging – Application to the functional analysis of neuronal networks in vivo." Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS455.
Full textThe neural code, i.e. how interconnected neurons can perform complex operations, allowing the quick adaptation of animals to their environment, remains an open question and an intensive field of research both in experimental and computational neurosciences. Advances in molecular biology and microscopy have recently made it possible to monitor the activity of individual neurons in living animals and, in the case of small animals containing only a few thousands of neurons, to measure the activity of the entire nervous system. However, the mathematical framework that would bridge the gap between single neuron activity and the emergent computational properties of neuronal ensembles is missing.In the thesis manuscript, we introduce a sequential statistical processing pipeline that efficiently and robustly extracts neuronal ensembles from calcium imagery of neuronal activity. In particular, we develop a Bayesian inference framework based on a biologically interpretable model to extract neuronal ensembles characterized by noise, asynchrony and overlapping. The provided tool demonstrates that a Gibbs sampling routine can efficiently estimate statistical parameters and hidden variables to uncover neuronal ensembles based on synchronization patterns both on synthetic data and on various experimental datasets from mice and zebrafish visual cortex to Hydra Vulgaris. The thesis equally develops a point process statistical framework to quantify how neuronal ensembles encode evoked stimuli or spontaneous behaviors in living animals. This versatile tool is also used for the inference of the functional connectivity of neuronal activity or the automatically calibration procedure of the spike inference algorithms applied to calcium recordings. For the providing algorithms to be largely spread in the neurobiologist community, results are supported by interpretable biological estimates, statistical evidence, rigorous mathematical proofs, and free-available software. Our contributive implementation, that goes from pixel intensity to estimated neuronal ensembles, equally identify from the synchronous firing patterns of neuronal ensembles, neurons with specific roles that can be used to predict, improve, or alter the behaviors of living animals. The provided framework unravels the emergence of collective properties from the recording of extremely varying individual signals that make the neural code still elusive
Suberbielle, Elsa. "Dysfonctionnement neuronal ou inflammation, les deux facettes des conséquences de la persistance du Bornavirus dans le système nerveux central : étude à l'aide d'outils de proteomique et d'immunologie." Toulouse 3, 2008. http://www.theses.fr/2008TOU30027.
Full textBorna disease virus (BDV) is an ideal model system for investigating the diverse pathological consequences of viral infections of the central nervous system (CNS). BDV persists in the CNS of a wide range of animal species and induces diverse neurological diseases. This work was aimed at studying two different aspects of BDV infection. First, we analyzed BDV-induced inflammation by assessing the interaction between antiviral cytotoxic T lymphocytes and primary cultures of neurons. Our results provide further evidence about the modalities of neuronal insult caused by CTL, a feature that characterizes also several neuroinflammatory diseases. Second, we performed a global analysis of the impact of BDV infection on the neuronal proteome. Taken as a whole, our results reveal selective interference with biological functions implicated with neuronal remodeling and provide further insight about the physiopathology of BDV persistence in neurons
Delvit, Jean-Marc. "Évaluation de la résolution d'un instrument optique par une méthode neuronale : application à une image quelconque de télédétection." Toulouse, ENSAE, 2003. http://www.theses.fr/2003ESAE0010.
Full textFauvel, Baptiste. "Particularités cérébrales anatomiques et fonctionnelles associées à l’expertise musicale : Quelles influences sur le vieillissement cognitif normal et sur la dynamique neurale de la mémoire de reconnaissance musicale." Caen, 2015. http://www.theses.fr/2015CAEN1005.
Full textThrough learning-related brain plasticity, individuals’ experiences could help building a cognitive reserve that favors a successfull cognitive aging. Many studies conducted with children reveal that musical learning promotes the development of cognitive functions. Therefore, the question of whether the involvment in musical practice in old age would also influence cognition has become a main topic of neuropsychology. This is what this thesis deals with, by featuring three correlational studies about the effect of musical expertise through anatomical and resting-state functional MRI data of young adult participants (study 1), behavioral measures obtained with adult and old individuals (study 2), and an effective connectivity analysis applied to activation-state functional MRI data recorded when young adult subjects performed a familiarity judgment task (study 3). Study 1 highlights that several brain regions were impacted by musical expertise, both in terms of gray matter volume and functional connectivity. Study 2 brings only poor clues in favour of a cognitive aging that would be reduced due to musical practice. Finally, study 3 shows that activity of the left hippocampus is elicited by an excitatory signal from the left inferior frontal gyrus in order to contribute to musical familiarity judgment, in musicians only. Methodologies and results of these three studies are discussed
Hristovska, Ines. "Dynamique microgliale en conditions physiologiques : un mécanisme contrôlé par les états de vigilance et l’activité neuronale." Thesis, Lyon, 2019. https://n2t.net/ark:/47881/m60c4v3q.
Full textMicroglia, the resident immune cells of the central nervous system (CNS), were traditionally believed to be set into action only by injury or diseases. Strikingly, in the healthy brain, microglia actively carry out parenchyma patrolling by extending and retracting their ramified processes. These movements are referred to as microglial motility and may be to some extent directed toward synapses. However, motility regulation and the purpose of microglia-spine contacts remain elusive. We thus examined the influence of neuronal activity on microglial motility, morphology and microglia-spine interactions during sleep and wakefulness. We found that microglial motility and morphology are modulated by vigilance states. Microglial processes were found to be attracted by active synapses particularly during wake, whereas sleep downregulates microglial proximity and activity-dependent contact with spines. Microglial contact resulted in increased spine activity which was mainly observed during sleep. Understanding the mechanisms regulating microglial dynamics and microglia-spine interactions across the vigilance states will provide further insights into how microglial cells may be involved in sleep- associated functions such as synaptic homeostasis, learning and memory. Grasping these cellular interactions in physiological conditions is crucial to understand synaptic functioning and alterations when microglia are engaged into their immune functions, a hallmark of most brain pathologies
Spelle, Laurent. "Imagerie fonctionnelle cérébrale en tomographie par émission de positons avec le [11C] flumazénil : modélisation des interactions ligand - récepteur et étude de la perte neuronale corticale en pathologie neurodégénérative." Paris 6, 2005. http://www.theses.fr/2005PA066038.
Full textDi, Rienzo Franck. "Plasticité cérébrale et corrélats neurofonctionnels de l'imagerie motrice après lésion médullaire : étude magnétoencéphalographique et applications en rééducation." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10264.
Full textNeuroplasticity can promote motor recovery after neurologic injuries. Neuroplasticity after complete spinal cord injury triggers adaptive reorganization of cerebral regions recruited during motor imagery (i.e., the mental representation of a movement without actually executing it). The neural processes underlying motor command inhibition, required to prevent physical execution of the imagined action, would no longer be relevant and may be weakened. Motor imagery may thus be an efficient approach to brain motor networks stimulation. Prehension is severely disturbed after C6-C7 quadriplegia. Upper limb motor functions spared by the neurologic injury afford motor learning of a compensatory prehension during rehabilitation. Due to its effects on neuroplasticity, our data suggest that motor imagery training enabled motor learning of new prehensile motor programs
Audoin, Bertrand. "Etude par IRM cérébrale multimodalitaire des supports morphologiques et fonctionnels des troubles cognitifs au stade initial de la sclérose en plaques." Aix-Marseille 2, 2004. http://www.theses.fr/2004AIX20686.
Full textGardier, Camille. "Etude de la coopération de l'alpha-synucléine et de LRRK2 dans les dysfonctions mitochondriales dans la Maladie de Parkinson." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS405.
Full textThe proteins alpha-synuclein (αsyn) and Leucine-Rich Repeat Kinase 2 (LRRK2) both play major roles in the physiopathology of sporadic and genetic forms of Parkinson’s Disease (PD). In particular, the G2019S mutation of LRRK2, located in its kinase domain, is the most prevalent cause of genetic forms of PD. It has been suggested that αsyn and LRRK2 could act together to induce the selective loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) in the pathogenesis of this disease. In our laboratory, it has been shown that G2019S LRRK2 could increase the dopaminergic cell loss induced by αsyn in the SNpc of rats, confirming the existence of a functional interaction between the two proteins. Moreover, it has been known for years that mitochondrial dysfunction played a major role in PD. Many studies showed that both LRRK2 and αsyn induced mitochondrial dysfunction. Therefore, we hypothesized that the functional interaction between αsyn and LRRK2 could take place through a common effect on mitochondria. We showed in vitro, in primary rat neurons, that G2019S LRRK2, but not the wild type (WT) form nor the dead kinase mutant (DK), significantly increased the number of neurons expressing a pathological form of αsyn (phospho-S129). This was not associated with any cell loss. At the cellular and molecular levels, there was a significant decrease in the mitochondrial ATP production rate in cells co-expressing LRRK2 (WT, G2019S and even more pronounced with DK) with αsyn, without any change in total ATP levels. The mean distance travelled by mitochondria along neurites was higher in neurons co-expressing αsyn and LRRK2 than in neurons only expressing αsyn. To summarize, in this in vitro model LRRK2 increases the somatic accumulation of a pathologic form of αsyn, in a kinase-dependent manner. In these conditions, mitochondria are able to maintain their homeostasis, in particular by adapting their ATP production rate. This seems to indicate a moderate mitochondrial stress induced by the co-expression of αsyn and LRRK2
Ruffino, Célia. "Etude des mécanismes comportementaux et neurophysiologiques consécutifs à un entrainement par imagerie motrice." Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCK027/document.
Full textFor many years, research in motor control, sport science and rehabilitation focused on the performance improvement following mental practice. However, some mechanisms, behavioral and neurophysiological, remain insufficiently understood. In our first study, we demonstrated the impossibility to predict the future performance improvement following imagined repetitions of a speed accuracy trade-off task, with a subjective evaluation of imagery ability of young healthy individuals. However, it is essential to produce clear and vivid mental simulations throughout the training to obtain a better performance improvement. Besides, by a further analysis of performance, the results of our second study have shown the real impact of mental training on the memorization of motor skills. Motor imagery training also appeared to be effective to compensate the motor memory deficit observed in the elderly. Finally, a third study revealed that the repetitions of imagined movements could modify, temporarily, the coding of neural networks involved in the motor memory process
Chariot, Alexandre. "Quelques applications de la programmation des processeurs graphiques à la simulation neuronale et à la vision par ordinateur." Phd thesis, Ecole des Ponts ParisTech, 2008. http://pastel.archives-ouvertes.fr/pastel-00005176.
Full textMenjot, de Champfleur Nicolas. "La voie ventrale sémantique du langage : une étude de connectivite anatomique, de connectivite fonctionnelle et de sa plasticité périopératoire." Thesis, Montpellier 1, 2012. http://www.theses.fr/2012MON1T012/document.
Full textAccording to classical conception of the anatomo-functional organization of language, there are two main cortical areas: a frontal area (Broca) and a temporal one (Wernicke) respectively involved in language production and comprehension. Functional magnetic resonance Imaging (fMRI) reveals cortical areas of activation and diffusion tensor imaging-based tractography (DTI) makes feasible the visualization of white-matter tracts in the human brain. On the basis of these techniques, a new conception of language cortical and sub-cortical organization arose, supporting the hypothesis that language processing network is dissociated in an dorso-ventral way. Dorsal areas of the brain being devoted to phonologic processing and its ventral areas to semantic processing of speech. Different techniques such as fMRI, DTI, intraoperative cortical and subcortical mapping made possible to describe two pathways involved in the language network: a dorsal stream and a ventral stream respectively involved in phonologic and semantic processing. As the dorsal route is composed of a unique pathway, the superior longitudinal fasciculus, the ventral stream appears to be composed of two different pathways. First a direct pathway, the inferior occipitofrontal fasciculus, connecting the posterior temporal areas to the orbitofrontal region. The second one, an indirect pathway, the inferior longitudinal fasciculus links the posterior occipitotemporal to the temporal pole, then relayed by the uncinate fasciculus connecting the temporal pole to the basifrontal areas. According to these observations the aim of our work is In the present work, we aim (1) to confirm that the MdLF is constantly found in control subjects and that it can be delineated from the other fiber tracts that constitute language pathways, (2) to characterize the reorganization of language network's functional connectivity follmowing surgical removal of left hemisphere low grade gliomas. In this study, we confirmed that the MdLF is constantly found in healthy volunteers and we clearly delineate the MdLF from the other fascicles that constitute language pathways, especially the ventral pathway. Considering language plasticity, our findings suggest that in the postoperative period, brain plasticity occurs with an ipsilateral recrutment and increased fonctional connectivity in the left hemisphere. Finally, we report a collaborative work observing that intraoperative electrostimulations of the white matter underlying the left posterior cingulate, while performing a naming task, systematically induced an unresponsive state for few seconds in relationship with a dream-like state. This result provides direct evidence that connectivity underlying the posterior node of the default mode network permits maintained consciousness of the external world
Le, Chapelain Loïc. "Contribution à l'étude de la reconstruction de l'image corporelle après lésion médullaire : influence de la stimulation calorique vestibulaire." Dijon, 2005. http://www.theses.fr/2005DIJOMU16.
Full textSalin, Hélène. "Analyse transcriptionnelle des mécanismes de la potentialisation à long terme,modèle de plasticité synaptique,et de leurs altérations au cours du vieillissement." Paris 11, 2002. http://www.theses.fr/2002PA11T015.
Full textLong-term potentiation (LTP), a model for synaptic plasticity, is characterised by a persistent increase in synaptic strength following tetanie stimulation of afferent fibres. Its maintenance is altered during ageing. The aim of the present work was to analyse, at a transcriptional level, first LTP mechanisms within the dentate gyrus and second changes in LTP during ageing. The work was performed using novel methods of quantitative analysis. These methods are more sensitive and best suited to address the physiological questions. Two of them rely on the analysis of messenger RNA expression at a cellular level: (i) the tridimensional reconstruction of expression levels of several mRNA within a structure and (ii) use of double radioactive labelling in in situ hybridisation allowing a comparative, quantitative and simultaneous analysis of two mRNA in a tissue section. The analyses of mRNA expression (Zif268, Homer, syntaxin lB, CaMKII, APP and a-synuclein) in the dentate gyrus following LTP induction, revealed the diversity in the transcriptional response within the structure both at the cellular and subcellular levels in young adult rats and during ageing. The results showed: (i) a heterogeneous spatio-temporal expression for Zif268, Homer et syntaxin lB in the dentate gyrus of young adult rats; (ii) an alteration of the transsynaptic transmission of LTP during ageing, and (iii) alterations of mRNA expression for APP[KPI-], CaMKII and asynuclein during ageing. These last results can potentially explain the lack of LTP maintenance in the dentate gyrus. In parallel, to allow a large-scale analysis of mRNA expression profiles in LTP, a microarray approach using two different radioelements was developped. This approach provided the sensitivity and the reproducibility that are required for the fine analysis of a physiological event such as LTP
Pelletier, Bruno. "Traitement neuronal de l'information hyperspectrale." Toulouse, ENSAE, 2002. http://www.theses.fr/2002ESAE0014.
Full textMuret, Dolly-Anne. "On the limits of cortical somatosensory plasticity and their functional consequences : a novel form of cross-border plasticity." Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10063/document.
Full textTouch plays a critical role in our daily life to grasp and manipulate objects, or simply walk. The primary somatosensory areas exhibit the striking feature of being somatotopically organized, giving rise to the so-called Homunculus. While most of our body surface is represented following an order similar to its physical continuity, the Homunculus displays a major discontinuity, the hand and the face being represented next to each other. The hand-face border has been widely used as a somatotopic hallmark to study one of the most fascinating features of our brain, its capacity for reorganization. Particularly, somatosensory plasticity was found to cross the hand-face border following deprivation of inputs. While it has long been known that increasing inputs also leads to cortical changes typically associated with perceptual benefits, whether such plasticity can cross the hand-face border remains unknown. My thesis work aimed to investigate this question. A first behavioural study revealed that increasing inputs to a finger improves not only the tactile acuity at this finger, but also at the face, suggesting a transfer of plastic changes across the hand-face border. To investigate this, two additional studies were performed using two complementary brain imaging techniques, namely high-field fMRI and MEG. In agreement with our hypotheses a reorganization of both hand and face representations was found. Altogether, this work reveals that adaptive plasticity leading to perceptual benefits can spread over large cortical distances, in particular across the hand-face border, and thus opens up a new window of investigation that may have a real impact in promoting rehabilitation
Colavita, Michelangelo. "Dynamics of hippocampal networks revealed by voltage sensitive dye imaging." Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0424.
Full textIn order to better understand brain functioning we need to investigate all the structural domains present in it, from single cell to interconnected entire brain regions. However, while our knowledge in terms of single/few cells functioning is vast, very little is known about neuronal networks, which are interacting collections of neurons functionally related to the same task. Moreover, the balanced and concerted activity of excitatory and inhibitory networks plays a key role for proper cortical computations. However, while exist several tools to record excitatory networks activity, this is not the case for inhibitory networks. Voltage sensitive dye imaging (VSDI) is a technique that allows the recording of neuronal activity by mean of proportional emission of fluorescence according to changes in membrane potential. The advantage of using VSDI over other recording techniques using electrodes is that VSDI allows not invasive recording of neuronal activity from hundreds of sites at the same time. During my doctoral course I aimed at studying in detail excitatory and inhibitory neuronal networks in the CA1 area of mouse hippocampus with VSDI. To study excitatory networks more comprehensively, in collaboration with a team of mathematicians, we developed a mathematical algorithm that allowed measuring the velocity and the direction of spreading of the VSDI signal and it represents a new method to determine an optical flow. After successful validation of the algorithm with surrogate data to test its accuracy, we analysed two set of experiments in which network excitatory activity has been manipulated either by increasing Schaffer’s collaterals stimulation intensity or by blocking GABAergic transmission with the GABAA receptor antagonist picrotoxin in order to increase the depolarization in the CA1 region of the hippocampus. The results of these manipulations significantly decreased signal velocity whereas picrotoxin application significantly modified the direction of spreading, making the depolarization-mediated VSDI signal less dispersed compared to control. Using VSDI I was able to fully characterize GABAA receptor-mediated hyperpolarizing signals in all the CA1 sublayers (field IPSPs), thus providing a new way of monitoring inhibitory events at network level. Moreover, I found that the activation of mGluR5 receptors induced an increase in a long-lasting manner of the VSDI-recorded field IPSPs, with duration and magnitude that relied on the specific CA1 sublayer considered. Overall, my work shows new methodologies and new findings that may represent a step forward in the quest for a better understanding of neuronal networks, both excitatory as well as inhibitory, which hopefully can contribute to reduce the gap of knowledge between single cell activity and behaviour
Levy, Jonathan. "Etude in cérébro des mécanismes inconscients lors de la lecture." Toulouse 3, 2010. http://thesesups.ups-tlse.fr/882/.
Full textWhile you are now reading this text, you are unaware of a complex series of extremely rapid processes which is taking place: Within less than 250 ms of viewing a written word, the visual system extracts the information needed to identify its linguistic significance. This complex endeavor is orchestrated by a network of specialized brain regions constantly communicating and trafficking information to and from each other, by discharging electrical pulses at various frequencies. On the surface, since those processes are highly automated, they operate underneath our level of consciousness. The aim of the present dissertation is to shed light on the complex brain dynamics underlying those unconscious processes, and thereby better comprehending the automated and efficient mechanism that we know as reading. To this aim, we used a variety of measurement-tools including fMRI, magnetoencelography, neuronal connectivity and behavioral measures. We first focused on the principal automatic processing steps sustaining reading, and illustrated their distribution and information routing inside the brain. We found that their spatio-functional recruitment follows bilateral-to-left and posterior-to-anterior gradients. Second, we pinpointed distinct anatomical pathways corresponding to the two famous routes for the processing of written language. As revealed, reliance on these neuronal pathways predicts reading skill - a finding, which potentially could be used in the future for the early identification of developmental dyslexia. Third, we sought to understand in what manner those processes access consciousness. We managed to pinpoint the perceptual boundary between the access to consciousness of lower and higher reading processes. The results suggest that localized neuronal oscillations mirror the "upgrading" of consciousness to a higher linguistic processing level. Altogether, this enterprise introduces an important contribution to the domain of reading with potential preventative applications, and additionally links it to the semi-controversial field of the neural correlates of consciousness
Grava, Cristian. "Compensation de mouvement par réseaux neuronaux cellulaires : application en imagerie médicale." Lyon, INSA, 2003. http://theses.insa-lyon.fr/publication/2003ISAL0096/these.pdf.
Full textThis work concern motion estimation and compensation in image sequences. The originality of this thesis consist in the proposed solutions for a fast implementation of the interpolation and motion compensation on an existing hardware structure based on Cellular Neural Networks (CNN). To improve the precision of classical motion estimation methods, we developed markovian approaches, taking into account the discontinuities in the motion field. The deterministic algorithms implemented for the minimization of the maximum a Posteriori energy are ICM and mean-field annealing. The motion compensation implemented on CNN is based on the motion field, already estimated. This is facilitated by the similitude between the neighbourhood in the Markov sense and the physical structure of the CNN. The performances of the proposed algorithms were studied on images from echography and X-ray tomography. The time-gain is several orders (until 10~) greater and they are an alternative to conventional solutions
Grava, Cristian Magnin Isabelle Buzuloiu Vasile. "Compensation de mouvement par réseaux neuronaux cellulaires application en imagerie médicale /." Villeurbanne : Doc'INSA, 2005. http://docinsa.insa-lyon.fr/these/pont.php?id=grava.
Full textLa, Rota Camilo. "Analyse de l'activité électrique multi-sites auditif chez le cobaye." Phd thesis, Grenoble 1, 2003. http://www.theses.fr/2003GRE19001.
Full textThe scientific problem that has motivated this study is the representation and processing of information in the neocortex. We are interested in particular in the hypothesis that states that information is coded on the neural populations' cooperative activities. This study is essential to find technological solutions to some medical problems, such as the development of neuroprosthesis. The existence of new multisite measuring techniques that allow the in vivo observation of the spatiotemporal activity of the cortex at high resolutions, give us the possibility to study the concept of "neural interaction" at mesoscopic scales and to study the mechanisms of senses and perception at the level of functional areas. We have studied in particular the electrical activity of the guinea pig's auditory cortex in response to stimuli using voltage-dependent dyes (optical imaging). We have studied some techniques for the processing and analysis of the spatiotemporal information represented by this data. By means of a descriptive analysis we have characterized the signals, their variability and the measuring errors. A theoretical study complemented this description, and allowed us to interpret our data in function of the underlying neural activity. Optical signals are difficult to process with traditional signal processing techniques, we have used wavelet-based techniques to estimate and characterize the neural activity components of the signal. Finally, we have evaluated some approaches to the spatiotemporal modeling of the cortical activity, and we have studied the pertinence of these models to describe our data. Some perspectives on this problem and on the design of future experiences are given
Lamirel, Cédric. "Bases neuronales du glaucome : une approche combinant psychophysique, oculomotricité et imagerie fonctionnelle cérébrale." Paris 6, 2012. http://www.theses.fr/2012PA066231.
Full textDecreased visual motion sensitivity in early stages of primary open angle glaucoma suggests that this pathology may impair complex visuo-cognitive tasks involving the magnocellular pathway and the dorsal cortical pathway that are specialized in motion analysis. This work is testing this hypothesis. In the first part, we demonstrated that saccades toward a static or a moving target are impaired. Saccade’s latencies are increased in early and moderate stages of glaucoma when the target is static, and even more when the target is moving. Saccade’s accuracy is decreased only in moderate stages of glaucoma when the target is static and in both early and moderate stages when the target is moving. In a second part, we used bistable stimuli to test neural processes of integration and segregation of complex visual motion. Glaucoma patients had fewer transitions between the 2 possible percepts for stimuli using contrast variations to induce bistability, although they did experience bistable motion with different stimuli. The quality of pursuit and fixation were decreased in glaucoma patients. Altogether these results show that glaucoma alters complex visuo-cognitive tasks before the detection of a scotoma by standard automated perimetry. The results suggest a diffuse impairment of the cortical and sub-cortical networks involved in eye movement, particularly in saccades. These anomalies could be the functional correlates of structural transsynaptic changes found in the superior colliculus, in the lateral geniculate nucleus and in the visual cortex. Our work indicates that evaluation of eye movements might be a useful marker of early damages of the anterior visual pathway in glaucoma
Colavita, Michelangelo. "Dynamics of hippocampal networks revealed by voltage sensitive dye imaging." Doctoral thesis, Università di Catania, 2015. http://hdl.handle.net/10761/3813.
Full textJouini, Manel. "Reconstruction des images couleur de l'eau sous les nuages : recours à des méthodes neuronales." Paris 6, 2011. http://www.theses.fr/2011PA066508.
Full textFoucher, Christophe. "Analyse et amélioration d'algorithmes neuronaux et non neuronaux de quantification vectorielle pour la compression d'images." Rennes 1, 2002. http://www.theses.fr/2002REN10120.
Full textGalerne, Pascal. "Détection et classification de cibles posées sur le fond marin par réseaux de neurones en imagerie sonar." Brest, 1998. http://www.theses.fr/1998BRES2022.
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