Дисертації з теми "Human brain- Neuroimaging"
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Burgess, Richard Ely. "Magnetic resonance imaging at ultra high field implications for human neuroimaging /." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1089949841.
Повний текст джерелаTitle from first page of PDF file. Document formatted into pages; contains xiv, 222 p. : ill. (some col.). Advisor: Pierre-Marie Luc Robitaille, Dept. of Emergency Medicine. Includes bibliographical references.
Krienen, Fenna Marie. "Large-Scale Networks in the Human Brain revealed by Functional Connectivity MRI." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:11081.
Повний текст джерелаPsychology
Meyniel, Florent. "How the human brain allocates physical effort over time : evidence from behavior, neuroimaging and pharmacology." Paris 6, 2013. http://www.theses.fr/2013PA066366.
Повний текст джерелаNo pain, no gain: optimal decisions involve a tradeoff between cost and benefit. We propose that in physical effort allocation, this tradeoff is unfolded over time. We present a task to investigate this process in the laboratory with healthy humans and we suggest a computational model to account for decisions to stop and resume the effort. Costs increase during exertion, due to fatigue at all stages of the motor command and decrease during rest, due to recovery. We show that this dynamic may be captured by a cost-evidence variable and compared to the expected benefit. Functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG) complementarily showed that cost-evidence may be implemented in proprioceptive regions of the brain: posterior insula and ventro-medial thalamus. In addition, MEG showed that motor beta (13-30 Hz) desynchronization mediates the effect of incentives to hasten effort resumption. This strategic invigoration of rest is supported by a behavioral dissociation: the expected utility (not the actual utility) modulates rest durations. Together, our results support that the behavior is adapted on the fly to cost-evidence levels and that this mechanism is modulated strategically according to the expected cost and benefit. This behavior was not affected by pain killers (hypnosis or paracetamol), but by serotonin (Escitalopram). This work bridges a gap between sport medicine, value-based decision-making and accumulation models in neuroscience in showing that accumulation and dissipation of cost-evidence can guide the optimization of effort allocation: this mechanism implements the maximization of benefit while the body costs are minimized
Manickam, Sameer. "Clustering-based approach for the localization of Human Brain Nuclei." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-284443.
Повний текст джерелаRoeder, Luisa. "Cortical control of human gait." Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/101537/1/Luisa_Roeder_Thesis.pdf.
Повний текст джерелаCórdova, Palomera Aldo. "Early Neurodevelopment, adult human cognition and depressive psychopathology: analysis of neuroimaging brain correlates and epigenetic mediators." Doctoral thesis, Universitat de Barcelona, 2015. http://hdl.handle.net/10803/328712.
Повний текст джерелаKirk, Ulrich. "The modularity of aesthetic processing and perception in the human brain : functional neuroimaging studies of neuroaesthetics." Thesis, University College London (University of London), 2007. http://discovery.ucl.ac.uk/1445135/.
Повний текст джерелаPutt, Shelby Stackhouse. "Human brain activity during stone tool production : tracing the evolution of cognition and language." Diss., University of Iowa, 2016. https://ir.uiowa.edu/etd/2133.
Повний текст джерелаCousijn, Helena. "Expression and neural correlates of schizophrenia risk gene ZNF804A." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:91c9b37f-5b7b-4400-b129-0c33e23ee6ed.
Повний текст джерелаUhrig, Lynn. "A study of the brain mechanisms of loss of consciousness during general anesthesia using non-human primate neuroimaging." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066339.
Повний текст джерелаHow can anesthetics induce a loss of consciousness during general anesthesia? A major challenge in neuroscience is to dissect the mechanisms of general anesthesia, which is quite difficult to achieve in the clinical conditions. The dawning of monkey functional MRI (fMRI) in neuroscience is an important opportunity to investigate neuronal activity in awake and anesthetized conditions. The recent development of auditory paradigms, such as the ‘local-global’ paradigm, that specifically explore brain networks thought to be specific of the conscious state led us to hypothesize that the combination of primate fMRI, auditory paradigms and single-drug anesthetic protocols with electroencephalography (EEG) control would help dissect the neuronal mechanisms of general anesthesia. In a first step, because we planned an extensive use of fMRI in our work, it was key to screen anesthetic agents for their effects on brain vascular oxygenation, a critical parameter for fMRI signal. Thus we did a preliminary experiment using ultra-high field MRI in rodents to assess subtle changes of the T2* signal under different anesthetic conditions and could demonstrate that propofol and ketamine, both clinical anesthetics, affects less brain blood oxygenation than volatile agents. In a second step, we developed a toolbox for awake and anesthetized monkey fMRI and validated the experimental set-up with a simple sound paradigm (low and high frequency sounds). In the third step, we tested the ‘local-global’ auditory paradigm in awake monkeys and could demonstrate that the macaque brain was capable of hierarchical predictive coding through a hypothetical macaque Global Neuronal Workspace made of frontal, parietal and cingulate cortices, in a striking homology with humans. In the fourth step, we tested the ‘local-global’ auditory paradigm in anesthetized monkeys and could demonstrate a progressive disorganization of the macaque GNW under anesthesia when increasing the levels of propofol sedation, and a complete suppression of the macaque GNW under deep ketamine sedation. These results are compatible with the hypothesis that the mechanism of loss of consciousness under anesthesia is related to the disorganization of a hierarchical GNW, with the parietal cortex as a common target among anesthetics. In the final step we studied the default network by acquiring resting state in awake and anesthetized monkeys and could demonstrate that under anesthesia, the brain still exhibits distinct and rich connectivity patterns, but these patterns become strongly related to the underlying white-matter structural map in a monotonic manner, while the awake state is characterized by a high degree of temporal flexibility which allows for a non-stereotyped exploration of a greater variety of brain states. In conclusion, by disorganizing the GNW, anesthetics alter the temporal dynamics of spontaneous brain activity, and specifically its departure from mere random fluctuations along established anatomical routes, leading to consciousness suppression
Johnen, Vanessa Mareike. "Non-invasive associative plasticity induction in a cortico-cortical pathway of the human brain." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:b1cd8707-9801-46aa-80f1-5d7231e59f1f.
Повний текст джерелаPissiota, Anna. "Fear, Startle, and Fear-Potentiated Startle : Probing Emotion in the Human Brain." Doctoral thesis, Uppsala University, Department of Psychology, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3479.
Повний текст джерелаThe present thesis explored the neurobiological basis of three aspects of defense behaviors in humans. Positron emission tomography methodology was used, and changes in regional cerebral blood flow (rCBF) were measured as an index of neural activity. Firstly, brain function was studied in a group of patients suffering from combat-related posttraumatic stress disorder, using a symptom provocation paradigm with combat sounds in order to elicit fear. Exposure to auditory trauma reminders relative to neutral sounds was associated with increased rCBF in sensorimotor areas, the cerebellar vermis, the periaqueductal gray matter, and the right amygdala, whereas decreased activity was observed in the retrosplenial area of the posterior cingulate cortex. Secondly, the neural circuitry mediating the acoustic startle response and its habituation was studied in a group of healthy subjects. During acoustic startle stimulation as compared to a resting condition, increased rCBF was found in a medial posterior area of the pons corresponding to the nucleus reticularis pontis caudalis. As a result of startle repetition, altered activity was found in the cerebellum, pointing to its involvement in startle habituation. Thirdly, neural activity associated with startle modulation by phobic fear was studied in a group of subjects with specific animal phobias during exposure to pictures of their feared and non-feared objects, paired and unpaired with acoustic startle stimuli. As a result of startle potentiation, increased rCBF was found in the left amygdaloid-hippocampal region, and medially in the affective division of the anterior cingulate cortex. In conclusion, these results provide evidence for the involvement of limbic and paralimbic brain areas during fear provocation and fear-potentiated startle and for a similar neurocircuitry underlying startle in humans and animals.
Li, Changhong [Verfasser], Björn M. [Akademischer Betreuer] Kampa, Frank [Akademischer Betreuer] Müller, and David [Akademischer Betreuer] Elmenhorst. "Impact of sleep on the A1 adenosine receptor, neuronal activity, and structural connectivity of the human brain : a multi-modal neuroimaging approach / Changhong Li ; Björn M. Kampa, Frank Müller, David Elmenhorst." Aachen : Universitätsbibliothek der RWTH Aachen, 2021. http://d-nb.info/1240390882/34.
Повний текст джерелаMarklund, Petter. "Cross-functional brain imaging of attention, memory and executive functions : unity and diversity of neurocognitive component processes /." Doctoral thesis, Umeå : Department of Psychology, Umeå University, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-805.
Повний текст джерелаMaingault, Sophie. "Surface-based characterization of healthy human adult cortex : An investigation of its morphological variability, late maturation and asymmetries." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0127/document.
Повний текст джерелаStudying the complexity of the human brain anatomy requires the characterization of multimodal and multiscale features obtained by recent in vivo neuroimaging techniques. In the present thesis, we benefited from up to date automated surface-based brain image analysis software to extract structural phenotypes of the human cerebral cortex, namely the cortical thickness, the surface area, the sulcal depth, the curvature and the intracortical myelin content. The principal aim of this work was to characterize multimodal structural variables on a large database of 450 healthy adults aged from 18 to 57 years (the BIL&GIN database) in order to describe the inter-individual variability of brain structural organization and notably the research of candidate markers for brain maturation and lateralization. We first took the example of the Heschl’s gyrus hosting the primary auditory cortex and having high variability due to the presence of different pattern of gyrus duplication coupled with strong interhemispheric differences. We showed that the partial or complete duplication of the Heschl’s gyrus was associated to loco-regional modifications in terms of cortical thickness, surface area and myelin located posteriorly to this gyrus and in the planum temporale, this two regions being implied in language processing. In a second study, we investigated the cortical structural modifications associated to late maturation (between 18 and 30 years) and cortical atrophy linked to aging. We revealed that the computation of a maturation index based on an integration of cortical thickness and intracortical myelin improved the discrimination of two different patterns of grey matter changes during these different stages of life. Finally, we characterized cortical asymmetries using a specific hemisphere surface matching which removed differences in sulcal morphology and position between both hemispheres. We highlighted regions where thickness and surface area asymmetries were concordant (leftward or rightward asymmetry for both anatomical variables) and regions of opposite asymmetries (leftward for one and rightward for the other). About 20% of regions that showed cortical thickness and surface area asymmetries presented negative correlation between these variables. It is striking that the two regions with the strongest anatomical asymmetries; the planum temporale and the superior temporal sulcus had rather positive asymmetry correlations. The planum temporale presented a leftward asymmetry of both cortical thickness and area while the superior temporal sulcus showed a right asymmetry of the two variables. This study demonstrated that there were correlations between thickness and surface area asymmetries, characteristics of the cortex organization. These areas are key sites for which it now remains to study the anatomical relevance as markers of brain lateralization and its functional correlates
Prince, Steven Eric. "Functional Neuroimaging Investigations of Human Memory Comparisons of Successful Encoding and Retrieval for Relational and Item Information." Diss., 2007. http://hdl.handle.net/10161/201.
Повний текст джерелаConroy, Susan Kim. "Chemotherapy, estrogen, and cognition : neuroimaging and genetic variation." Thesis, 2014. http://hdl.handle.net/1805/4027.
Повний текст джерелаThe time course and biological mechanisms by which breast cancer (BC) and/or alterations in estrogen status lead to cognitive and brain changes remain unclear. The studies presented here use neuroimaging, cognitive testing, genetics, and biomarkers to investigate how post-chemotherapy interval (PCI), chemotherapy-induced amenorrhea (CIA), and genetic variation in the estrogen pathway affect the brain. Chapter 1 examines the association of post-chemotherapy interval (PCI) with gray matter density (GMD) and working memory-related brain activation in BC survivors (mean PCI 6.4, range 3-10 years). PCI was positively associated with GMD and activation in the right frontal lobe, and GMD in this region was correlated with global neuropsychological function. In regions where BC survivors showed decreased GMD compared to controls, this was inversely related to oxidative DNA damage and learning and memory scores. This is the first study to show neural effects of PCI and relate DNA damage to brain alterations in BC survivors. Chapter 2 demonstrates prospectively, in an independent cohort, decreased combined magnitudes of brain activation and deactivation from pre-to post-chemotherapy in patients undergoing CIA compared to both postmenopausal BC patients undergoing chemotherapy and healthy controls. CIA’s change in activity magnitude was strongly correlated with change in processing speed, suggesting this activity increase reflects effective cognitive compensation. These results demonstrate that the pattern of change in brain activity from pre- to post-chemotherapy varies according to pre-treatment menopausal status. Chapter 3 presents the effects of variation in ESR1, the gene that codes for estrogen receptor-α, on brain structure in healthy older adults. ESR1 variation was associated with hippocampus and amygdala volumes, particularly in females. Single nucleotide polymorphism (SNP) rs9340799 influenced cortical GMD and thickness differentially by gender. Apolipoprotein E (APOE)-ε4 carrier status modulated the effect of SNP rs2234693 on amygdala volumes in women. This study showed that genetic variation in estrogen relates to brain morphology in ways that differ by sex, brain region and APOE-ε4 carrier status. The three studies presented here explore the interplay of BC, estrogen, and cognition, showing that PCI, CIA, and ESR1 genotype influence brain phenotypes. Cognitive correlates of neuroimaging findings indicate potential clinical significance of these results.
Kashuk, Sam. "Investigation of MRI Brain Changes in Developmental Coordination Disorder and Friedreich’s ataxia." Thesis, 2017. https://vuir.vu.edu.au/33211/.
Повний текст джерелаRodrigues, João. "New methodologies for directed functional connectivity applied to brain neuroimaging research." Doctoral thesis, 2015. http://hdl.handle.net/10451/18375.
Повний текст джерелаIn the last decade directed functional connectivity analysis has been increasingly adopted as a method to study the information transfer in the human brain. However, its use with functional neuroimaging data has faced several limitations and controversies, especially when applied to functional magnetic resonance imaging (fMRI) data. This thesis presents a study of directed functional connectivity metrics and their application to datasets from two of the most widely used functional neuroimaging techniques, electroencephalography (EEG) and fMRI. Since a major part of this work focuses on testing and benchmarking connectivity metrics in controlled simulations, an initial study was performed on known generative models, with varying degrees of biophysical fidelity, for the former datasets. Its results suggested that less realistic models are more suitable for large simulations, due to their computational efficiency, or for testing novel metrics, due to their increased control over simulated causal relations. The following study provided a thorough performance assessment of directed functional connectivity metrics in broad experimental simulations with synthetic fMRI data. Our conclusions argued in favor of their applicability in the context of fMRI, provided that a stringent set of experimental specifications is met. The two succeeding studies proposed a novel framework for causal inference, oriented to EEG data, with the use of adaptive data analysis. Their findings suggested that this new framework is able to not only provide improved frequency localization but also to restrict causal analysis to components with physical meaning. The last study provided the opportunity to apply some of the knowledge gathered throughout these studies in the analysis of intracranial EEG data from a patient with infantile spams. From studying the causal relations in the recorded data it was possible to delineate a seizure onset zone that is consistent, and even more specific, with regions determined clinically or by novel localization strategies.
Na última década a análise de conectividade funcional direccionada tem sido progressivamente adoptada no estudo da conectividade do cérebro humano. No entanto, a sua utilização com dados de neuroimagem funcional tem enfrentado uma série de limitações e controvérsias, especialmente quando aplicado a dados de ressonância magnética funcional (fMRI). Esta dissertação apresenta um estudo de métricas de conectividade funcional direccionada e na sua aplicação a registos de duas das técnicas de neuroimagem funcional mais utilizadas, electroencefalografia (EEG) e fMRI. Uma vez que uma grande parte deste trabalho consiste em testar e avaliar estas métricas recorrendo a simulações controladas, foi realizado um estudo inicial sobre os modelos generativos mais recorrentes na literatura, com diferentes graus de fidelidade biofísica, para EEG e fMRI. Os resultados sugeriram que os modelos menos realistas são mais adequados para grandes simulações, devido a requisitos computacionais baixos, ou para testar novas métricas, devido ao maior controle sobre as relações causais simuladas. O segundo estudo consistiu numa avaliação do desempenho da análise de conectividade funcional direccionada em simulações extensas com dados de fMRI sintéticos. As conclusões argumentaram a favor da aplicabilidade a dados fMRI, desde que um rigoroso conjunto de especificações experimentais seja cumprido. Os dois estudos seguintes propõem uma nova abordagem para a inferência causal através da análise de dados adaptativa. Os resultados sugerem que esta abordagem é capaz de, não só proporcionar uma melhor localização em frequência, mas também de restringir a análise causal a componentes com significado físico. No último estudo são efectuadas análises de causalidade em registos EEG intracranianos de um paciente com espasmos infantis. A partir do estudo das relações causais nestes registos, foi possível delinear uma zona epileptogénica consistente, e ainda mais específica, com as regiões determinadas clinicamente ou por novas estratégias de localização.
Zivadinov, R., G. U. Poloni, K. Marr, C. V. Schirda, C. R. Magnano, E. Carl, N. Bergsland, et al. "Decreased brain venous vasculature visibility on susceptibility-weighted imaging venography in patients with multiple sclerosis is related to chronic cerebrospinal venous insufficiency." 2011. http://hdl.handle.net/10454/6252.
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