Thèses sur le sujet « Cortically »
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Means, Eric. « Designs for a cortically-inspired neurocomputer architecture / ». Full text open access at:, 1991. http://content.ohsu.edu/u?/etd,267.
Stewart, Robert Douglas. « Spiking neural network models of the basal ganglia : cortically-evoked response patterns and action selection properties ». Thesis, University of Sheffield, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.445121.
Palminha, Catia. « Assessing the role of FLNA and NR2F1, associated with periventricular heterotopia, in the formation and maturation of cortical networks ». Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0159.
Proper brain function depends on the adequate production and positioning of neurons, the formation of correct neuronal connectivity, and requires a strict balance of excitatory and inhibitory synapse formation. Mutations in genes that normally carve and sustain these processes can alter neuronal functions and lead to various neurodevelopmental disorders in humans, including malformations of cortical development (MCD). MCDs are important causes of mental retardation and account for 20% - 40% of drug-resistant epilepsy cases in children. Among the many types of MCD, periventricular nodular heterotopia (PNH) is the most common form in adulthood and is caused by defective radial glia that result in ectopic neural nodules lining the walls of the lateral ventricles. About 88% of PNH patients have focal epilepsy and the severity of seizures can range from mild to rare frequency and remission without the need for antiepileptic drugs to insoluble. Several genes have been identified as a genetic cause of PNH in patients, including FLNA and NR2F1. No correlation between the extent of PNH and the severity of epilepsy was found, suggesting that aberrant circuits in the normotopic cerebral cortex rather than heterotopic nodules could explain the occurrence of seizures. We studied the in vivo impact of the loss of these genes during dendritogenesis and synpatogenesis, as well as in the morphology and functional maturation of cortical neurons
NEIDECKER, GUILLEMETTE. « Atrophies cerebrales corticales focalisees primaires : a propos d'une observation d'atrophie corticale posterieure ». Lyon 1, 1993. http://www.theses.fr/1993LYO1M186.
Vallet, Quentin. « Predicting bone strength with ultrasonic guided waves ». Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066626.
We aimed at developing new ultrasound-based biomarkers of cortical bone to enhance fracture risk prediction in osteoporosis. Our approach was based on the original concept of measuring ultrasonic guided waves in cortical bone. The bi-directional axial transmission technique was used to measure the guided modes propagating in the cortical envelope of long bones (i.e., the radius). Strength-related structural and material properties of bone were recovered from the dispersion curves through an inversion scheme. To this goal, a fully automatic inverse problem based on genetic algorithms optimization, using a 2-D transverse isotropic free plate waveguide model was developed. The proposed inverse procedure was first tested on laboratory-controlled measurements performed on academic samples with known properties. Then, the feasibility of estimating cortical properties of ex vivo radius specimens was assessed. The inferred bone properties were validated by face-to-face comparison with reference values determined by a set of independent state-of-the art technologies, including X-ray micro-computed tomography (thickness, porosity) and resonance ultrasound spectroscopy (stiffness). A good agreement was found between reference values and estimates of thickness, porosity and stiffness. Lastly, the method was extended to in vivo measurements, first, by ensuring the validity of the waveguide model in presence of soft tissues to demonstrate the feasibility of measuring experimental dispersion curves in vivo and infer from them bone properties. Estimated cortical thickness values were consistent with actual values derived from high resolution peripheral computed tomography
Alecu, Lucian. « Une approche neuro-dynamique de conception des processus d'auto-organisation ». Phd thesis, Université Henri Poincaré - Nancy I, 2011. http://tel.archives-ouvertes.fr/tel-00606926.
Markov, Nikola. « Exploration of the inter-areal cortico-cortical network of the macaque monkey ». Phd thesis, Université Claude Bernard - Lyon I, 2010. http://tel.archives-ouvertes.fr/tel-00863803.
Briot, Karine. « Macroarchitecture et résistance osseuse : rôle de l'os cortical ». Phd thesis, Université d'Orléans, 2009. http://tel.archives-ouvertes.fr/tel-00485695.
El, Waly Bilal. « Contribution à l'étude des bases génétiques de la polymicrogyrie ». Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM5041.
Polymicrogyria is a cortical malformation characterized by excessive gyration and an irregular cortex surface. Environmental and genetic causes can be responsible for this disorder. Our principal aim was to better understand the genetic basis of polymicrogyria. Three projects were conducted. The first focused on the NHEJ1 gene. Using RNA interference and in utero electroporation, we showed that deregulation of NHEJ1 disrupts neuronal migration, triggers massive neuronal cell death and disorganizes the cortical layers. In the second project, we identified by comparative genomic hybridization microarray, a duplication in the 1p36 region in a patient with bilateral polymicrogyria. We have shown that this duplication breaks the ENO1 gene and reduces its expression. The spatio-temporal expression of ENO1 and the fact that its deregulation disrupts neuronal migration indicates that ENO1 is a good candidate gene for cortical development. Finally, in the third project, we identified by exome sequencing of familial cases of bilateral polymicrogyria, one coding variation in the GABRA3 gene. Our work allowed us to generate new knowledge for several candidate genes for polymicrogyria
Broix, Loïc. « Compréhension des mécanismes physiopathologiques des malformations du développement cortical associées à des mutations dans les gènes KIF2A et NEDD4L ». Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCB103/document.
Malformations of cortical development (MCD) result from alterations in different stages of corticogenesis such as proliferation, migration and neuronal differentiation, and are generally associated with drug-resistant epilepsy and severe intellectual disabilities. The genetics causes of MCD remain largely unknown, we have thus performed the whole-exome sequencing of many patients with MCD and reported the identification of multiple pathogenic missense mutations in KIF2A and NEDD4L genes. Within the frame of my thesis project, we propose to focus on the cellular and neurodevelopmental consequences resulting from KIF2A and NEDD4L mutations shown to be involved in MCD. KIF2A is a member of the kinesin-13 family, which rather than regulating cargos transport along microtubules (MT), regulates MT dynamics by depolymerizing MTs. The in utero electroporation approach allowed us to highlight the crucial role of KIF2A in the regulation neurogenesis, neuronal migration and the neuronal positioning in the cortex. Particularly, our data show that the expression of the KIF2A mutants involved in MDC lead to an increase in the number of cells in proliferative state which is a consequence of a prolonged time spent in the cell cycle. Our first cellular data and during development show that the expression of pathogenic KIF2A mutations induce alterations in the mitotic spindle integrity, in the mitotic progression and also an abnormal localization of KIF2A in the primary cilium. NEDD4L encodes a member of the NEDD4 family of HECT-type E3 ubiquitin ligases known to regulate the turnover and function of a number of proteins involved in fundamental cellular pathways and processes. Firstly, cellular and expression data showed sensitivity of MCD-associated mutants to proteasome degradation. Moreover, the in utero electroporation approach showed that PNH-related mutants and excess wild-type NEDD4L affect neurogenesis, neuronal positioning and terminal translocation. Further investigations, including rapamycin-based experiments, found differential deregulation of pathways involved. Excess wild-type NEDD4L leads to disruption of Dab1 and mTORC1 pathways, while MCD-related mutations are associated with deregulation of mTORC1 and AKT activities. Altogether, these results reinforce the importance of MT-related proteins in cortical development describing the crucial role of KIF2A kinesin in mechanisms such as neuronal migration dynamics and neuronal progenitor’s cell cycle regulation. On the other hand, we also provide new data to better understand the critical role of NEDD4L in the regulation of mTOR pathways and their contributions in cortical development
Chaigne, Agathe. « Cortical stiffness : a gatekeeper for spindle positioning in mouse oocytes ». Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066288/document.
Meiotic divisions are highly asymmetric divisions in size, generating a big cell, the oocyte, and two tiny cells, the polar bodies. This asymmetry is ensured by the migration of the first meiotic spindle to the closest cortex. This migration does not depend on microtubules but on Myosin-II and an F-actin meshwork nucleated by cooperation of straight filament nucleators Formin-2 and Spire1/2. Preliminary studies in the lab described a thickening of the F-actin cortex during spindle migration, but paradoxically cortical tension, a physical parameter describing the stiffness of the cell, drops during spindle migration. I have shown that this thickening is required for spindle migration and nucleated by the branched actin nucleator Arp2/3, under the control of the Mos/MAPK pathway. Furthermore, it promotes the decrease in cortical tension by triggering the delocalization of Myosin-II from the oocyte cortex, which is crucial for spindle migration. Finally, I have shown that the drop in cortical tension is an amplificatory mechanism to the initial unbalance of forces (due to a slight off-centered position of the nucleus) triggering the motion of the spindle
Plá, Requena Virginia Teresa. « Cortical alterations of peptidergic secretion in Alzheimer's disease = Alteraciones corticales de la secreción peptidérgica en la enfermedad de Alzheimer ». Doctoral thesis, Universitat de Barcelona, 2017. http://hdl.handle.net/10803/456816.
La enfermedad de Alzheimer es un trastorno neurodegenerativo caracterizado por la presencia de placas seniles y ovillos neurofibrilares causados por la acumulación patológica del péptido β-amiloide y la hiperfosforilación de Tau, respectivamente. En la actualidad, la enfermedad de Alzheimer constituye la principal causa de demencia y su principal factor de riesgo es el envejecimiento. Dado que se han detectado alteraciones progresivas en los niveles de neuropéptidos en pacientes y modelos animales de la enfermedad de Alzheimer, se ha sugerido que esta vía pueda estar implicada en la neurofisiología de la enfermedad. En esta tesis doctoral se realiza un estudio de las alteraciones corticales de la vía de secreción peptidérgica en la enfermedad de Alzheimer. Durante su elaboración se ha caracterizado la localización de las proteínas de los gránulos densos en el cerebro normal y patológico, encontrándose acúmulos aberrantes de las mismas en las estructuras patológicas típicas de la enfermedad, como son los cuerpos de degeneración granulovacuolar o las neuritas distróficas. El estudio del efecto agudo del péptido β-amiloide permitió hallar una reducción de la liberación regulada tanto en neuronas y astrocitos in vitro como en rodajas de cerebro agudas en respuesta al tratamiento, sugiriendo que la vía de secreción puede suponer una diana temprana de la patología. Finalmente, el estudio de los niveles de proteínas características de la vía ha mostrado una reducción de sus niveles en el líquido cefalorraquídeo de animales transgénicos y pacientes de la enfermedad con deterioro cognitivo leve, lo que parece indicar que las proteínas de la vía pueden ser candidatas como biomarcadores que permitan la monitorización del avance de la enfermedad de Alzheimer.
Saavedra, Leos María Dolores. « Estudio de la composición de los gránulos corticales y del oolema de ovocitos porcinos y bovinos madurados y fecundados in vitro ». Doctoral thesis, Universidad de Murcia, 2009. http://hdl.handle.net/10803/10863.
Polyspermy (entering of more than a spermatozoon into the oocyte) is a pathological condition in mammals since it avoids the normal embryonic development. In the pig species, Polyspermy is a common problem still unsolved in the current systems of in vitro fertilization (IVF). The cortical granules (CGs) from mammal's oocytes are involved in the block to polyspermy. However, little is known about the composition and function of these organelles. It is widely described that the molecules released of the CGs during the fertilization or oocyte activation, by means of chemical or electrical stimulation, produce important modifications, particularly in the zona pelucida (ZP), the periviteline space and, probably, oolema of the oocyte. These modifications have a direct role in the block to polyspermy. The knowledge about the content of the CGs and the oolema proteins of as well as their role during fertilization in pigs is still scarce. The majority of the information that we currently have it has been obtained from the murine model. In the present Doctoral Thesis, we investigated the presence of possible proteins of the CGs in pig oocytes as well as the presence of metaloproteases ADAM-10 and ADAM-17 in pig and bovine oocytes. For that, this study was divided into three sections
Bennabi, Isma. « Importance de l’architecture des microtubules et de l'actine pour l'alignement des chromosomes dans l'ovocyte de souris ». Thesis, Paris Sciences et Lettres (ComUE), 2018. https://tel.archives-ouvertes.fr/tel-02943886.
Meiosis produces male and female haploid gametes. Female meiosis is highly prone to chromosome segregation errors. Indeed, at least 10 % of human pregnancies produce aneuploid embryos, the errors leading to aneuploidy almost always occurring in the oocyte. Understanding the origin of these errors is therefore a major issue. During my PhD, I studied chromosome alignment and segregation in mouse oocytes from two different angles:1) In eukaryotes, the structure orchestrating chromosome alignment and segregation is the microtubule spindle. Whereas mitotic spindles assemble from two centrosomes that are major microtubule organizing centers (MTOCs) containing centrioles, meiotic spindles in oocytes lack centrioles. Thus, oocytes use alternative ways to assemble and position their spindle. In mouse oocytes, the spindle is not assembled by centrosomes but spindle microtubules are nucleated from multiple acentriolar MTOCs. I used the kinesin-14 HSET as a tool to shift meiotic spindle assembly towards a mitotic mode. This induces severe chromosome misalignment. Thus, the unique mechanism of meiotic spindle assembly is essential to prevent chromosome misalignment and production of aneuploidy gametes.2) In mitosis, centrosomes nucleate astral microtubules. Oocytes lack astral microtubules and thus meiotic spindle positioning depends only on F-actin. In particular, it relies on the nucleation of a cortical actin thickening leading to a decrease in cortical tension. We used two different tools that nucleate de novo an actin thickening to artificially decrease cortical tension in mouse oocytes, creating extra-soft oocytes. Chromosome alignment is severely impaired in these extra-soft oocytes. It relies on myosin II deregulation since decreasing myosin II activity in extra-soft oocytes rescues chromosome alignment. Aberrant low cortical tension could thus generate aneuploidy in oocytes, contributing to the very high aneuploidy rate measured in female meiosis
Corlier, Fabian. « Étude de l’imagerie amyloïde cérébrale et de l’élargissement des endosomes dans les cellules sanguines au cours de la maladie d’Alzheimer ». Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066687/document.
Alzheimer’s disease (AD) diagnostic is based on clinical and biological criteria, and is dependent on impairment of the episodic memory together with a marker of the underlying pathophysiologic process. One of the earliest events in AD pathology in the brain is formation of Amyloid deposits in the extracellular space. One of the main subcellular sites of amyloid-β (Aβ) production from amyloid precursor protein (APP) processing is the endosomal compartment. Appearance of endosomal abnormalities precede the formation of amyloid deposits, in the brain areas affected by disease progression in AD. In the present work we first studied brain amyloid load in patients with posterior cortical atrophy using [11C]PiB ligand retention in positron emitting tomography (PET). In a second part we studied the endosomal compartment in peripheral cells (fibroblasts and mononuclear leucocytes, PBMC) from AD patients, and in lymphoblastoid cell lines (LCL) from Down’s syndrome (DS) individuals where a third copy of amyloid-precursor-protein-coding gene located on chromosome 21 is known to initiate early Alzheimer’s pathology in most DS individuals. Our work shows similar profiles in topography and intensity of [PiB] binding in AD and posterior cortical atrophy (PCA), confirming underlying AD pathology in atypical focal presentations of AD. Analysis of endosomes yielded a significant increase in the frequency of cells with large endosomes in all analyzed cell types, and mean endosome volume correlated to [PiB] binding in PBMC. This result indicates that modifications of the endosomal compartment are seen in the periphery of central nervous system and may represent diagnostic tool from blood
Taytard, Jessica. « Interactions croisées cognition-respiration et conséquences d’une activation de la commande ventilatoire corticale : étude chez le sujet sain et les patients atteints du syndrome d’hypoventilation alvéolaire centrale congénitale ». Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS378.
In humans, the ventilatory drive can arise from cortical structures. This cortical control is responsible in healthy subjects for the compensation of mechanical inspiratory loading. In patients with congenital central hypoventilation syndrome (CCHS), the cortical ventilatory drive is involved in compensating the inefficient automatic command. The aim of this study was to demonstrate a competition between cerebral resources leading to impaired cognitive performances and/or altered ventilation in: 1- healthy subjects submitted to inspiratory threshold loading (ITL); and 2 – CCHS patients during spontaneous breathing (SB). Twenty-five healthy subjects and seven CCHS patients were studied using neuropsychological tests. In healthy subjects, the tests were performed during SB and while subjects were breathing against the ITL. In CCHS patients, tests were performed during SB and while patients were breathing with their own ventilatory support. The impact of different conditions was studied by ventilatory recordings and cortical connectivity and pre-inspiratory potential analyses. Dyspnea was evaluated using the Multidimensional Dyspnea Profile questionnaire (MDP). In healthy subjects, breathing against the ITL induced breathing pattern modifications, dyspnea and cortical activation. It was associated to decreased performances tests evaluating attention capacities. In patients, SB led to cortical activation associated to desaturations, and an increase in breathing variability and in apnea frequency during neuropsychological tests. We demonstrated a competition between cognition and ventilation when the latter is depending on cortical resources
Bizzotto, Sara. « Eml1 in radial glial progenitors during cortical development : the neurodevelopmental role of a protein mutated in subcortical heterotopia in mouse and human ». Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066118.
The cerebral cortex develops through genetically regulated processes of cellular proliferation, neurogenesis, migration and differentiation. Cortical malformations represent a spectrum of heterogeneous disorders due to abnormalities in these steps, and associated with epilepsy and intellectual disability. We studied the HeCo (heterotopic cortex) mutant mouse, which exhibits bilateral subcortical band heterotopia (SBH), characterized by many aberrantly positioned neurons in the white matter. We found that Eml1 (Echinoderm Microtubule-associated protein-Like 1) is mutated in these mice. Screening of EML1 in heterotopia patients identified mutations giving rise to a severe and rare form of atypical heterotopia. In HeCo embryonic brains, progenitors were identified outside the normal proliferative ventricular zone (VZ), representing a novel cause of this disorder. We studied Eml1 function in radial glial progenitors (RGCs), which are important during corticogenesis generating other subtypes of progenitors and post-mitotic neurons, and serving as guides for migrating neurons. We showed that Eml1 localizes to the mitotic spindle where it might regulate microtubule dynamics. My data suggest a role in the establishment of the steady state metaphase spindle length. Indeed, HeCo RGCs in the VZ showed a perturbed spindle length during corticogenesis, and this may represent one of the primary mechanisms leading to abnormal progenitor behavior. I also analyzed cell number and metaphase cell size at the apical side of the VZ, where mitosis occurs. I thus propose new mechanisms governing normal and pathological VZ progenitor organization and function during cortical development
Marsan, Elise. « Mise en évidence de l'implication de la voie GATOR1-mTORC1 dans les épilepsies et dysplasies corticales focales ». Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066495.
In my PhD thesis work, I investigated focal epilepsies with and without brain malformations such as focal cortical dysplasia. I focused on two complementary aspects: (1) genetics and functional studies on human tissue samples and (2) characterization of a novel genetic animal model. First, germline heterozygous loss-of-function mutations were identified in DEPDC5, NPRL2 and NPRL3 genes that encode proteins which together form the GATOR1 complex, a repressor of the mTOR complex 1 (mTORC1). Additionally, brain somatic gain-of- function mutations were identified in MTOR gene that encodes mTOR itself. Both types of mutations are thought to lead to mTORC1 hyperactivity, and cause brain malformation and epilepsy in patients. To test this hypothesis, mTORC1 activity was monitored on post-operative brain tissue from patients carrying GATOR1 or mTOR genes mutations. Cytomegalic cells with mTORC1 hyperactivity were observed. Besides, the characterization of the first Depdc5 KO model revealed that Depdc5+/- rats present cortical structural abnormalities reminiscent of patient histopathology hallmarks: cortical layer dyslamination and cytomegalic cells with increased mTORC1 activity. This phenotype was prevented by rapamycin injection, a specific mTORC1 inhibitor. An increased susceptibility to pentylenetetrazol-induced epileptic seizures, as well as impaired passive and active neuronal properties were observed in Depdc5+/- rats compared to Depdc5+/+ rats. In conclusion, my PhD work largely contributed to emphasize the prominent role of the GATOR1-mTORC1 pathway in focal cortical dysplasia and epilepsies
Carment, Loic. « Le contrôle moteur et oculomoteur dans la schizophrénie : l’attention et la modulation de l’excitabilité corticale : principaux contributeurs du déficit sensorimoteur ? Manual dexterity in schizophrenia - A neglected clinical marker ? Manual dexterity and aging : a pilot study disentangling sensorimotor from cognitive decline ». Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS265.
Sensorimotor, attention and working memory impairments have been consistently reported in schizophrenia, even at an early stage of its evolution. The presence and severity of these deficits may, from the prodromal stage, predict the course of the disease. However, the interaction between cognitive and sensorimotor impairments and their related neural correlates remain uncharted. In this study, we wanted to assess whether attentional and working memory processing contribute to sensorimotor impairment in a visuomotor grip force tracking task in 25 stabilized patients with schizophrenia, 17 unaffected healthy siblings and 25 healthy age and gender-matched controls. Subjects performed a visuomotor grip force tracking task with increasing cognitive load: (i) simple tracking, (ii) tracking with visual distractors (requiring inhibition of saccades), and (iii) tracking with addition of numbers (requiring saccades). During the visuomotor tracking task, gaze was simultaneously recorded and cortical excitability and inhibition were assessed using transcranial magnetic stimulation. The behavioral and physiological results, obtained in this thesis, pinpoint altered attentional processing (divided attention and filtering of irrelevant information) and an imbalance of cortical excitability and inhibition as key contributors to sensorimotor impairments in schizophrenia. Moreover, altered task-related modulation of cortical excitability and inhibition in siblings is consistent with a genetic risk for cortical abnormality
Dehghani, Nima. « Electromagnetic signature of human cortical dynamics during wakefulness and sleep : = Signature électromagnétique de la dynamique corticale pendant l'éveil et le sommeil chez l'homme ». Phd thesis, Université Pierre et Marie Curie - Paris VI, 2012. http://tel.archives-ouvertes.fr/tel-00728697.
Paluch, Ewa. « Motilité cellulaire sur des systèmes simplifiés : de l' oscillation au mouvement dirigé ». Paris 7, 2005. http://www.theses.fr/2005PA077075.
Macchione, Silvia. « Topography of the perceptual improvement induced by repetitive somatosensory stimulation ». Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1302.
Touch plays a fundamental role in our daily activities. It has long been known that, thanks to brain plasticity, tactile acuity can be improved following training. Another form of tactile improvement, independent from training, can be achieved through a simple mechanical stimulation of a small region of the skin, called repetitive somatosensory stimulation (RSS). RSS of a finger was well known to improve tactile acuity locally (on the stimulated finger) and also remotely (on the face). However, topography of tactile improvement, especially on other unstimulated fingers, was unknown. In addition, the hypothesis of applying the RSS to another body region (notably the face) and investigate the possible effects, both in face and fingers, was not explored. The aim of this work of thesis was therefore investigating the topography of the RSS-induced tactile improvement within and between body regions. One first study revealed that RSS of a finger induces tactile improvement both locally and remotely in fingers. The second study showed that, when applied on the face, RSS is able to induce tactile improvement both locally, on the face, and remotely, in the hand, demonstrating that the tactile improvement between the hand and the face is bidirectional. Overall, the experimental data I provide constitute a significant contribution to the study of the topography of RSS-induced tactile changes
Ayache, Samar. « Étude neurophysiologique de l’excitabilité corticale et du tremblement dans la sclérose en plaques ». Thesis, Paris Est, 2014. http://www.theses.fr/2014PEST0027.
Our work focused on: 1) the study of cortical excitability changes in the treatment of multiple sclerosis (MS) relapses and the natural history of progressive forms of MS; 2) the characterization of action tremor, which is frequently observed in the course of the disease and is a major source of disability. This has led to the realization of five studies. The first study demonstrated that a rapid improvement in motor performance can be observed following treatment of MS relapses by intravenous corticosteroids administered daily over several days, accompanied by significant changes in cortical excitability parameters studied by transcranial magnetic stimulation techniques. These changes focused on the balance between GABAergic and glutamatergic influences in the motor cortex. An increase in cortical excitability occurs well before any possibility of remyelination or axonal regeneration, demonstrating a functional improvement induced by the treatment. In the second study, different parameters of cortical excitability were followed over one year in patients with progressive MS, treated or untreated. This study showed a decrease of intracortical inhibition and increased motor threshold at rest in untreated patients, accompanying a worsening of clinical disability scores. In contrast, treated patients remained stable, both on clinical and neurophysiological parameters. These results show that the evolution of progressive MS is associated with a global and progressive impairment of motor cortex excitability, concerning both pyramidal neurons on inhibitory control circuits, probably due to the progression of cortical neuronal loss over time. Our results also showed that different types of immunomodulatory therapy can stop this evolutionary course. In a third study, we characterized the existence of action tremor in 32 MS patients using electromyographic and accelerometer recordings in the upper limb. These recordings confirmed the existence of a real tremor in only one patient. Concomitant neurophysiological study of cerebellar and pontine circuits of control showed that most of the clinical aspects of tremor in MS in fact revealed a pseudo-tremor largely due to cerebellar dysfunctions. Our last two studies have clarified this result by means of an analysis of the electromyographic and accelerometer signal using empirical mode decomposition associated with Hilbert-Huang transform. This method of analysis appears valid and effective to characterize tremor or pseudo-tremor occurring in MS patients and to distinguish them from other types of tremor, such as essential tremor
Uzquiano, López Ana. « Progenitor cell mechanisms contributing to cortical malformations : studying the role of the heterotopia gene Eml1/EML1 in radial glia Eml1 loss impairs apical progenitor spindle length and soma shape in the developing cerebral cortex Cortical progenitor biology : key features mediating proliferation versus differentiation ». Thesis, Sorbonne université, 2019. https://accesdistant.sorbonne-universite.fr/login?url=http://theses-intra.upmc.fr/modules/resources/download/theses/2019SORUS392.pdf.
Cerebral cortical development is a finely regulated process, depending on diverse progenitor cells. Abnormal behavior of the latter can give rise to cortical malformations. Mutations in Eml1/EML1 were identified in the HeCo mouse, as well as in three families presenting severe subcortical heterotopia (SH). SH is characterized by the presence of mislocalized neurons in the white matter. At early stages of corticogenesis, abnormally positioned apical radial glia progenitors (aRG) were found cycling outside the proliferative ventricular zone (VZ) in the HeCo cortical wall. I focused my research on characterizing aRG in the VZ to assess why some cells leave this region and thus to further understand SH mechanisms. Combining confocal and electron microscopy (EM), I uncovered abnormalities of centrosomes and primary cilia in Eml1-mutant aRGs: primary cilia are shorter, and often remain basally oriented within vesicles. Searching for Eml1-interacting partners using mass spectrometry (MS), combined with exome sequencing of SH patient DNAs, allowed us to identify a ciliary Eml1-interacting partner, RPGRIP1L, showing mutations in a SH patient. Gene ontology analyses of MS data pointed to Golgi apparatus and protein transport as enriched categories. Indeed, Golgi abnormalities were identified in HeCo aRGs. Altogether, these data indicate that the Golgi-to-primary cilium axis is perturbed in Eml1mutant conditions, pointing to new intracellular pathways involved in severe neurodevelopmental disorders
Fernandez, Laura. « Dynamiques corticales de l'éveil chez la souris : rôle des afférences thalamo-corticales ». Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10199.
The activity in the brain during wakefulness has been typically described as rapid, low amplitude and desynchronized. However, recent data on rodents support evidence for a more complex panel of activities depending on the behaviour. For instance, it has been shown in mice a state change in primary somatosensory cortex (S1) from quiet to active wakefulness while the animal is scanning the environment with its whiskers. In the first study, we show that this state change in S1 is under thalamic control and to a smaller extent a regulation by the cholinergic system. In order to study the underlying mechanism of the state change, we have recorded in S1 and the thalamus, and we have activated (optogenetic tools) or inactivated (with pharmacology) the thalamus. In the second part of this thesis work, we asked if the state change related to the behaviour was restricted to S1, or if it was also observed in other areas. We have done multiple recordings in several areas, and we show that it is possible to observe a state change related to muscular activity in sensori-motor areas (in S1, but also secondary sensory S2, and primary motor M1 cortex), and in a much less prominent extent in other sensory modalities (primary auditive Au1 and primary visual V1 cortex), in parietal associative cortex (PtA) and in hippocampus (dCA1). Thus, the multiple recordings in the secondary study show heterogeneity of cortical activities during wakefulness according to the behaviour and the cortical area recorded
Del, Grosso Veronica. « Cortical microvessels and the tripartite synapse in chronic pain studied with synchrotron radiation ». Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAS034/document.
Chronic pain (CP) is a complex sensory disorder characterized by structural changes, i.e. severe anatomical rearrangements of somatosensory cortex, and functional changes, i.e. anomalies in network functional connectivity and in information transmission at the level of thalamo-cortical circuit. From the structural point of view, within each cortical module, a morpho-functional unit can be recognized, also called neuro-glial-vascular unit, where the glial cells represent the bridging structures allowing for the transfer of metabolites and oxygen to neurons. Namely, the functional dependency between neuronal and vascular elements, largely explored by 3D confocal microscopy and two photon microscopy, has expanded the concept of synaptic space to a more complex form, indicated as “tripartite synapse”, where besides the presence of the pre- and post- synaptic neurons, a glial component is added facing on the microvascular context. Due to this dependency it appears, thus, correct to analyse the cortical microscopical effects of the macroscopical picture. Novel studies by our group have recently investigated CP origin and evolution in experimental CP rat models (Seltzer) through microstructural and functional analyses focused both on the cortical neuronal substrate and the blood micromorphological and vasculodynamic properties. The 3D microarchitecture of cortical vascular network has been revealed by means of synchrotron X-ray micro Computed Tomography (CT) at the ID17 and ID16A beamlines (ESRF, Grenoble) and the TOMCAT beamline (SLS, Villigen). A subsequent morphometric analysis of the 3D vascular network has been implemented by means of skeletonization and spatial graph transformation. Then, a comparative study “Neuropathic vs Control”, based on the estimated vascular network properties (number of vessels, branch points, skeleton segments and vessel diameter), showed evident changes in cortical microvascular compartments: a widespread increase of blood microvessels and capillaries in the investigated regions (the somatosensory [SSI] cortical area) has been found in all CP rats. In parallel, a reduced mean value of vessel diameter in all CP rats prove that capillaries and small microvessels are predominantly interested by these angiogenetic events. By investigating the time evolution of the neogenesis, it appears strongly present since the first stage of the neuropathy (2 weeks), fading away, but still present, during the last time stage considered (6 months). In addition, an increased maximum blood flow, sustained by the vascular network, has been found in CP condition, indicating that CP vascular networks are compatible with an enriched blood flow sustained by the promoted novel angiogenesis. These results from micro- and nano-tomography have been further confirmed also by immunofluorescence microscopy analysis: CP samples have shown the positivity to three markers of vascular neo-genesis (VEGFR1, VEGFR2 and VWF). In parallel, to functionally analyse the genesis and the evolution of the thalamo-cortical circuits in CP conditions, the neural activity has been recorded by means of 32-microelectrode matrices implanted in the brain, simultaneously receiving signals from the VPL thalamic nucleus and the SS1 cortex. All the CP groups show connectivity disorders exhibited also by the evolution of the network topology from “Modules and Hubs” to a “random” network organisation where the intra-community and inter-community functional connections decrease. These results clearly confirm how the neuronal dynamics is strictly linked to the vascular activity: the cortical microvessel neo-genetic events in CP are strongly correlated to the functional anomalies in neuronal network dynamic. The microvascular involvement in CP opens a new way of interpretation of CP disease, not only recognized as sensory pathology, but also as a neurological disease where neuronal and vascular connectivity networks are extensively involved in the whole system
Grehl, Stephanie. « Stimulation-specific effects of low intensity repetitive magnetic stimulation on cortical neurons and neural circuit repair in vitro (studying the impact of pulsed magnetic fields on neural tissue) ». Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066706/document.
Electromagnetic fields are widely used to non-invasively stimulate the human brain in clinical treatment and research. This thesis investigates the effects of different low intensity (mT) repetitive magnetic stimulation (LI-rMS) parameters on single neurons and neural networks and describes key aspects of custom tailored LI-rMS delivery in vitro. Our results show stimulation specific effects of LI-rMS on cell survival, neuronal morphology, neural circuit repair and gene expression. We show novel mechanisms underlying cellular responses to stimulation below neuronal firing threshold, extending our understanding of the fundamental effects of LI-rMS on biological tissue which is essential to better tailor therapeutic applications
Beguin, Shirley. « Conséquences physiopathologiques des mutations du gène ARX dans le développement cérébral ». Thesis, Aix-Marseille 2, 2011. http://www.theses.fr/2011AIX22130/document.
Several mutations in ARX gene (aristaless-related homeobox gene) have been found in a large spectrum of infantile neurological disorders, with or without cerebral malformation, but frequently linked to epilepsy. It has been proposed that ARX, coding for a transcription factor, plays a crucial role in brain development, especially in migrating interneurons, but its involvement in nervous system development still remains to be clarified. The aim of this work has been to study the role of ARX gene and the consequences of ARX mutations on cerebral development in order to better understand these pathologies.We have first investigated the effects of an ARX polyalanine expansion, the mutation (GCG)7, which was found in pathologies without brain malformation but associated to epilepsy, such as West and Ohtahara syndromes. Analysis performed on knock-in mice for this mutation and in utero electroporated rat brains have shown that this mutation doesn’t alter neither glutamatergic and GABAergic neuronal migration, nor GABAergic neuron maturation. Interestingly, our data suggest that epilepsy observed in knock-in mice would result rather from a reorganization of glutamatergic networks. Since ARX gene is not expressed in excitatory neurons, our work suggests that epilepsy observed in knock-in mice is the consequence of developmental alterations secondary to the initial mutation, and this would have crucial therapeutic implications that require additional investigations. In vitro experiments have then allowed us to study the effect of several ARX mutations on interneurons morphology. These experiments have shown no abnormal subcellular localization of ARX protein following transfection of these different mutations in cultured interneurons. Interestingly, our data show that interneuron morphology is altered only by some mutations, particularly the P353R and the Dup24 ARX mutations. Our data underline the importance to study specifically each mutation in order to explain mechanisms generating phenotypic heterogeneity linked to ARX mutations.Taken together, this study contributes to a better understanding of ARX involvement in cerebral development and to a better characterization of pathophysiological mechanisms linked to ARX mutations
RIVAUD, SOPHIE. « Effets des lesions corticales et sous-corticales sur les saccades oculaires chez l'homme ». Paris 6, 1995. http://www.theses.fr/1995PA066451.
Bodin, Clémentine. « Le cortex vocal chez le primate : une investigation anatomo-fonctionnelle ». Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0647.
Vocal communication, which is integrated into human language, can also be found in the behavior of other primates. The question is whether these similarities are reflected in similar cerebral processes of this information. This thesis aimed to explore the anatomical and functional substrates of voice perception in primates by adopting a comparative approach. It was structured around two main research axes: I. The anatomical-functional investigation of temporal voice areas (TVAs) in relation to the anatomy of the superior temporal sulcus (STS) in humans. In this perspective, functional activity in the TVAs was found maximal in the deepest region of the STS bilaterally. However, this relationship was less systematic at the individual level, mainly due the presence of plis de passage (PP) that constitute an important source of variability. Investigation of the underlying structural connectivity revealed that they constituted preferential white matter crossing places connecting the two banks of the sulcus. II. In a second axis, we performed a comparative study of voice areas in humans and monkeys through functional imaging. Several voice areas (brain areas more sensitive to human voice in humans and to monkey vocalizations in monkeys compared to vocalizations of other species or non-vocal sounds) were found in both species, mainly in the temporal lobe. Together, the results suggest the existence of a complex cortical network dedicated to the processing of conspecific vocalizations, relatively conserved across primates and exhibiting a high individual variability inherent in its high-level social functions
Favali, Marta. « Formal models of visual perception based on cortical architectures ». Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066094/document.
The objective of this thesis is to develop mathematical models of visual perception based on cortical architectures and to apply them to reproduce phenomenological experiments and to process natural images. We primarly focus on low level vision tasks and in particular we are interested in the problem of grouping and of individuation of perceptual units. In this setting we will face the problem of the reconstruction of illusory figures and the detection of retinal vessels in optical images. Then we consider the problem of encoding and decoding of the fMRI signal from in vivo acquired brain activity of visual cortex. This allows to estimate the structure of the cortex of a specific human patient and eventually to reconstruct the visual stimulus from fMRI activity, in a so called “brain reading” strategy. The difference between our approach and the state of the art literature consists in using previously defined neuromathematical models of the cortices as a-priori knowledge to regularise in vivo estimated structure. Even if it is a long term objective, we propose a first approach to improve the results in this field. The entire work of this thesis has been developed taking into account results from phenomenology of perception and results of neurophysiology.In the field of the phenomenology of perception, at the beginning of the last century, the theory of the Gestalt psychology [Wertheimer, 1938, Kohler, 1947, Kofka, 1935] defined the integration of contours and in particular they defined grouping laws underlying perception. These are crucial in the construction of visual objects: points with characteristics in common can be grouped together to form a new visual object. Many psychophysical experiments have been proposed to measure the quantitative parameters of these laws. A particular interest of this thesis is the concept of association fields introduced by Field et al. [1993] which encodes different Gestalt principles (as good continuation, proximity). They showed that stimulus co-linearity and co-circularity play an important role for the feature of grouping. Their study showed how chances of perceiving the curvilinear path were high if the orientation of its features was the one tangent at that point and collapsed as their relative orientation deviated from being tangent
Balança, Baptiste. « Analyse neurochimique des dépolarisations corticales envahissantes après un traumatisme crânien sévère : existe-il un continuum entre une réponse physiologique et une crise métabolique ? » Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10205/document.
“Traumatic brain injury” (TBI) encompasses a heterogeneous group of physio-pathological phenomenon. Prognosis, clinical course evaluation and treatment of brain trauma remain challenging. Brain damage results from both the initial physical insult (primary injury), and also continues to occur in the ensuing hours to days because of secondary brain aggressions. Among secondary injuries following TBI, Cortical Spreading Depolarizations (CSD) have emerged since the mid-90s. CSD are waves of depolarization propagating along the cortex at a speed of 1-5 mm/min that induced a massive energetic demand to repolarize the cells. CSD are participating to prognosis because their occurrence and duration are related to outcome in different acute brain injuries (TBI, sub-arachnoid hemorrhage and ischemic stroke). During my thesis, our main goal was to determine whether the CSD reinforced neuronal death following brain trauma that can explain the poor prognosis. In a first study we delineated brain regions where neuronal death occurs following lateral fluid percussion injury (LFPI) in order to record CSDs in this area. Then, as we wanted to assess the energetic balance of this tissue during CSD using biosensors, we had primarily to check for the biosensor reliability to oxygen (O2) and temperature (To). As oxygen and temperature were different from bench (in vitro) to bedside (in vivo) monitoring, we developed algorithms to compute offline the in vivo values obtained for glucose, lactate or glutamate brain concentrations respecting the local O2 concentrations and To measured in the cortex. Finally, using the biosensors, we described the dynamic real time metabolic changes occurring after CSDs in 3 conditions: A healthy cortex, an injured cortex after LFPI, and when CSD occurred in cluster after LFPI. Although the normal brain displayed a hyper-glycolytic state following CSD (transient low glucose concentrations + prolonged elevated lactate concentrations), TBI tissue exhibited a different pattern that could be metabolic crisis (very low glucose concentrations + normal to low lactateconcentrations)
Dubreuil, Alexis. « Mémoire et connectivité corticale ». Thesis, Paris 5, 2014. http://www.theses.fr/2014PA05T036/document.
The central nervous system is able to memorize percepts on long time scales (long-term memory), as well as actively maintain these percepts in memory for a few seconds in order to perform behavioral tasks (working memory). These two phenomena can be studied together in the framework of the attractor neural network theory. In this framework, a percept, represented by a pattern of neural activity, is stored as a long-term memory and can be loaded in working memory if the network is able to maintain, in a stable and autonomous manner, this pattern of activity. Such a dynamics is made possible by the specific form of the connectivity of the network. Here we examine models of cortical connectivity at different scales, in order to study which cortical circuits can efficiently sustain attractor neural network dynamics. This is done by showing how the performance of theoretical models, quantified by the networks storage capacity (number of percepts it is possible to store), depends on the characteristics of the connectivity. In the first part we study fully-connected networks, where potentially each neuron connects to all the other neurons in the network. This situation models cortical columns whose radius is of the order of a few hundred microns. We first compute the storage capacity of networks whose synapses are described by binary variables that are modified in a stochastic manner when patterns of activity are imposed on the network. We generalize this study to the case in which synapses can be in K discrete states, which, for instance, allows to model the fact that two neighboring pyramidal cells in cortex touches each others at multiple contact points. In the second part, we study modular networks where each module is a fully-connected network and connections between modules are diluted. We show how the storage capacity depends on the connectivity between modules and on the organization of the patterns of activity to store. The comparison with experimental measurements of large-scale connectivity suggests that these connections can implement an attractor neural network at the scale of multiple cortical areas. Finally, we study a network in which units are connected by weights whose amplitude has a cost that depends on the distance between the units. We use a Gardner's approach to compute the distribution of weights that optimizes storage in this network. We interpret each unit of this network as a cortical area and compare the obtained theoretical weights distribution with measures of connectivity between cortical areas
Borius, Pierre-Yves. « Application neurochirurgicale de la tractographie et de la stimulation corticale et sous corticale ». Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30131.
Tractography and intraoperative stimulation would optimize tumor resection preserving the quality of life. The principles of diffusion tensor, tractography and brain stimulation are shown. A study of tractography of optic radiation and validation on a lesion model was able to confirm the feasibility of the reconstruction. Among the tested algorithms, the most effective was the "Tensor Line" predicting a risk of quadrantanopia when more than 5% of the trajectories have an intersection with the lesion volume. The second part focused on the cognitive process of language whose translation by cortical stimulation during awake surgery for 7 bilingual patients. Twenty-six interference tasks area were found but none was specific to the translation, which is complex to study. Finally, the prospects for integration of these 2 techniques are discussed through three clinical cases
Gay, Olivier. « Marqueurs neurodéveloppementaux en psychiatrie : intérêt dans les troubles schizophréniques ». Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCB016/document.
The term neurodevelopment in its broadest sense refers to all of the processes encompassing development of the nervous system from the earliest stages of formation in utero to later stages of maturation during adolescence to produce the fully functional adult nervous system. Work over the last thirty years has led to a neurodevelopmental model of human psychiatric disorders, including schizophrenia, based on genetic, epidemiological and imaging evidence. This model asserts that disease is fundamentally linked to or develops from abnormality(s) in the formation processes (early neurodevelopment) and maturation (late neurodevelopment) of the nervous system due to a combination of genetic and environmental factors. In this context this thesis aims to clarify the effects of neurodevelopmental abnormalities on psychiatric disorders, including schizophrenia, through the study of different markers. The first study aims to investigate correlations between markers of early brain development: a clinical marker (neurological soft signs) and an imaging marker (sulcation of the cerebral cortex) in a population of subjects with schizophrenia. A correlation between these two markers is presented: the sulcation index was found to be lower in subjects that had significant neurological soft signs. We concluded that the combined study of different markers may help to isolate subgroups of patients with greater early neurodevelopmental damage. The second study aims to characterize effects of different markers of early neurodevelopmental abnormalities on cognitive functioning in patients with schizophrenia. Effects on executive control (as measured by the Trail Making Test) were correlated with clinical markers (neurological soft signs, handedness) and imaging (sulcation of the anterior cingulate cortex and enlargment of the ventricles). We found interactions between different markers with a mainly non-linear summation effect. Our interpretation is that different markers reflect separate insults, though all early, on brain development with a common final effect on executive function. The third study aims to clarify the specificity of sulcation as a marker of early neurodevelopmental abnormalities by studying a population of adult subjects with autism spectrum disorder (ASD), a patholody beginning in early childhood and linked with evidence of early neurodevelopmental damage. Sulcation abnormalities of the anterior cingulate cortex, similar to those observed in patients with schizophrenia are detected in patients with ASD. These results suggest early neurodevelopmental abnormalities are shared by different psychiatric disorders and that changes in cortical sulcation are not specific to a given disorder but the early damage. In conclusion, we suggest that the study of neurodevelopmental abnormalities should be integrated into a dimensional approach in psychiatry
Bajaj, Sahil, Anna Alkozei, Natalie S. Dailey et William D. S. Killgore. « Brain Aging : Uncovering Cortical Characteristics of Healthy Aging in Young Adults ». FRONTIERS MEDIA SA, 2017. http://hdl.handle.net/10150/626429.
Tannan, Vinay Tommerdahl Mark Allen. « Novel sensory testing methods for the quantitative assessment of cortical-cortical interactions ». Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2007. http://dc.lib.unc.edu/u?/etd,1013.
Title from electronic title page (viewed Dec. 18, 2007). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Biomedical Engineering." Discipline: Biomedical Engineering; Department/School: Medicine.
Proudfoot, Malcolm. « Cortical neurophysiology of ALS ». Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:5b8673f7-8eb2-4bf2-b3b8-d901fa134007.
Le, Friec Julien. « Huntingtine et développement cortical ». Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAV016/document.
Huntington disease (HD) is an autosomal dominant inherited neurological disorder conducting to the appearance of motors, psychiatrics and cognitives symptoms during mid-adulthood. HD is characterised by a massive neurodegenerescence of both striatal and cortical neurons. HD is caused by a mutation in coding region of the protein Huntingtin (HTT) leading to the production of a mutated form (mHTT). mHTT gain new toxic function but also loss some of normal function of HTT. Therefore, studying both gain and loss of function is mandatory to better understand the physiopathological progression of HD.HTT and mHTT both contribute to development of cerebral structures. Our hypothesis is that developmental defects induced by mHTT could contribute at least in part to the physiological progression of HD. Our work focuses on cerebral cortex development a structure which is largely impacted in HD. Our previous studies demonstrated roles of HTT and the effect of mHTT in neuronal precursor proliferation during neurogenesis. However, roles and functions of HTT and mHTT during later step of cortical neurogenesis remain elusive.My PhD project has focused on two main aspects: (i) study the function of HTT in newborn post-mitotic neurons in cerebral cortex, notably during their migration and maturation, and (ii), characterising cortical neurogenesis in genetically integrated mouse model of HD: zQ175
Tard, Céline. « Modulation corticale de la locomotion ». Thesis, Lille 2, 2015. http://www.theses.fr/2015LIL2S067/document.
Patients with Parkinson 's disease present gait impairments, sometimes sudden and unexpected, either improved or deteriorated with environmental stimuli. Attention focalization, either on external stimuli or on gait, could then modulate locomotion.The main objective was to better characterize how environmental stimuli would modulate locomotion, via attentional networks, in healthy subjects and in parkinsonian patients, with or without freezing of gait.At first, we precisely defined the attentional deficits in patients, with or without gait impairment. They showed altered performance respectively in mental flexibility and in divided attention.Then, we explored the attention-locomotion interaction by studying motor preparation. So, we highlighted that anticipatory postural adjustments were a sensitive marker of attention. In patients, they evidenced an alteration of the attention-motor program interaction.Studying the brain activation during the visuo-driven locomotion in these patients confirmed the involvement of cortical attentional regions. We observed an imbalance inside the parieto-premotor network (useful to modulate motor action according external stimuli)Finally, we tried to change the excitability of the premotor cortex with transcranial magnetic stimulation to modulate visuo-driven locomotion
GONZALEZ, ASTRUC SYBILLE. « Etude comparative clinique et tomodensitometrique des aphasies corticales et sous-corticales : a partir de 43 observations ». Toulouse 3, 1988. http://www.theses.fr/1988TOU31299.
Soteropoulos, Demetris Soteris. « Studies on primate cortical and sub-cortical contributions to bi-manual co-ordination ». Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615080.
Ponce, Alvarez Adrián. « Probabilistic models for studying variability in single-neuron and neuronal ensemble activity ». Thesis, Aix-Marseille 2, 2010. http://www.theses.fr/2010AIX20706.
A hallmark of cortical activity is its high degree of variability. The present work focused on (i) the variability ofintervals between spikes that single neurons emit, called spike time irregularity (STI), and (ii) the variability inthe temporal evolution of the collective neuronal activity. First, I studied the STI of macaque motor corticalneurons during time estimation and movement preparation. I found that although the firing rate of the neuronstransmitted information about these processes, the STI of a neuron is not flexible and is determined by thebalance of excitatory and inhibitory inputs. These results were obtained by means of an irregularity measure thatI compared to other existing measures. Second, I analyzed the neuronal ensemble activity of severalsomatosensory and motor cortical areas of macaques during tactile discrimination. I showed that ensembleactivity can be effectively described by the Hidden Markov Model (HMM). Both sensory and decision-makingprocesses were distributed across many areas. Moreover, I showed that decision-related changes in neuronalactivity rely on a noise-driven mechanism and that the maintenance of the decision relies on transient dynamics,subtending the conversion of a decision into an action. Third, I characterized the statistics of spontaneous UP andDOWN states in the prefrontal cortex of a rat, using the HMM. I showed that state alternation is stochastic andthe activity during UP states is dynamic. Hence, variability is prominent both during active behavior andspontaneous activity and is determined by structural factors, thus rending it inherent to cortical organization andshaping the function of neural networks
Martel, Marylie. « Comprendre l’interaction entre la douleur et le système moteur : une étude novatrice combinant la stimulation magnétique transcrânienne et l’électroencéphalographie ». Mémoire, Université de Sherbrooke, 2016. http://hdl.handle.net/11143/9511.
Abstract : The interaction between pain and the motor system is well-known in clinic. For instance, it is well documented that pain significantly complicates the rehabilitation of the patients. The aim of the present study was to better understand the cortical mechanisms underlying the interaction between pain and the motor system. Nineteen healthy adults participated in the study. The effect of pain (induced with a capsaicin cream) on brain activity and on the corticomotor system was assessed with electroencephalography (EEG) and transcranial magnetic stimulation (TMS), respectively. For EEG, 15 non-overlapping, 2-seconds artifacts were randomly selected for each participant. Intracranial source current density and functional connectivity was determined using sLORETA software. When participants experienced experimentally-induced inflammatory pain, their resting state brain activity increased significantly in the central cuneus (theta frequency), left dorsolateral prefrontal cortex (alpha frequency), and both left cuneus and right insula (beta frequency; all ts >3.66; all ps<0.01). A pain-evoked increase in the right primary motor cortex (M1) activity was also observed (beta frequency), but only among participants who showed a simultaneous reduction in the strength of the corticospinal projections (quantified using the recruitment curves obtained with TMS; t=4.45, p<0.05). These participants further showed greater beta motor-cuneus connectivity than participants for whom pain did not affect M1 somatotopy (t=3.58, p<0.05). These results suggest that pain-evoked increases in M1 beta power are intimately tied to alterations in corticospinal system. Moreover, we provide evidence that beta motor-cuneus connectivity is related to the corticomotor alterations induced by pain.
Desmaris, Elodie. « Etude du rôle des facteurs de transcription Dmrt3 et Dmrt5 dans le développement cortical : Dmrt3 et Dmrt5 maintiennent l'identité corticale dans les progéniteurs du télencéphale dorsal au cours du développement ». Doctoral thesis, Universite Libre de Bruxelles, 2020. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/309310.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
Boucher, Maxime. « Shape analysis of cortical folds ». Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104620.
La surface corticale du cerveau humain contient plusieurs plis, ou sillons, qui juxtaposés forment un motif cohérent. Pour plusieurs raisons biologiques, la géométrie du motif formé par les plis corticaux change avec le temps: les plis deviennent plus longs, plus ouverts et plus creux. La relation entre la forme des plis corticaux et plusieurs facteurs biologiques, tels que le vieillissement et le genre du sujet peut être étudiée en utilisant des méthodes statistiques d'analyse de formes.Une étape essentielle de l'analyse statistique de la forme du cerveau humain est la mise en correspondance des sillons de surfaces corticales différentes. La mise en correspondance peut se faire à l'aide d'un champ scalaire décrivant la profondeur relative des sillons sur une surface. La correspondance entre les sillons est établie en comparant le champ scalaire respectif de chaque surface. La première contribution de cette thèse est de décrire un champ scalaire rapide à calculer et qui caractérise la profondeur relative des sillons sur une surface. L'utilisation du champ scalaire proposé dans cette thèse a amené une amélioration de 11% de la précision de la mise en correspondance. La seconde contribution de cette thèse est une méthode statistique permettant de localiser des différences directionnelles dans la forme des plis. Par exemple, un sillon plus long aura une différence de longueur dans la direction parallèle au sillon. La méthode statistique présentée dans cette thèse permet de déterminer la direction selon laquelle la forme des sillons diffère le plus. Les autres méthodes statistiques ne pouvant que déterminer si localement deux sillons sont différents, la méthode proposée dans cette thèse procure davantage d'information pour comprendre la forme des sillons.La troisième contribution de cette thèse est de proposer une méthode de diffusion anisotrope sur la surface corticale afin de faire ressortir les différences qui affectent la forme des sillons. La diffusion de champs scalaires et de tenseurs est utilisée afin d'augmenter la capacité de détection des tests statistiques. Par contre, la diffusion réduit aussi la capacité de localisation des méthodes statistiques. Avant cette thèse, la diffusion sur la surface se faisait de façon isotrope et l'information sur la forme des sillons était diffusée sur une région couvrant plusieurs sillons. La diffusion anisotrope permet d'augmenter le pouvoir de détection des tests statistiques sans pour autant réduire la capacité de mettre en évidence une différence dans la forme qui est localisée à un sillon spécifique.Le résultat de cette thèse est qu'il est possible d'analyser la forme des sillons du cortex cérébral en utilisant une méthode générale d'analyse de déformations. La précision de la mise en correspondance a été augmentée, l'analyse des champs de déformations permet de déterminer si une différence affecte la longueur ou la largeur du sillon et la diffusion utilisée pour augmenter la puissance des tests statistiques permet de mettre en évidence des différences dans la forme qui est localisée à un sillon spécifique.
Wilcock, Paul. « Cortical processing and perceived timing / ». [St. Lucia, Qld.], 2006. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe19761.pdf.
Haigh, Sarah. « Visual discomfort and cortical hyperexcitability ». Thesis, University of Essex, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.573696.
Roopun, Anita Kumari. « Cortical network oscillations in vitro ». Thesis, University of Leeds, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426852.
Ridding, Michael Charles. « Cortico-cortical connections in man ». Thesis, University College London (University of London), 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321574.