Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 30 for “"Hemodynamic response"”.
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Dynamic state-space estimation of the hemodynamic response with Near-Infrared Spectroscopy
… Spectroscopy (NIRS) allows the recovery of the hemodynamic response associated with evoked brain activity. The signal is contaminated with systemic physiological interference which occurs in the superficial layers of the head as well as in the brain tissue. The back-reflection geometry of the …
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Cerebral hemodynamic response to faces and emotions in infants at high risk for autism
… is therefore to characterize the specific neural response of face processing in infants with near-infrared spectroscopy (NIRS), and to then apply these measures to the study of abnormal face processing in infants at high risk for autism. In order to achieve these objectives, the work described …
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Eye Movements and Hemodynamic Response during Emotional Scene Processing: Exploring the Role of Visual Perception in Intrusive Mental Imagery
… stressful or traumatic event. Gaze patterns and hemodynamic response from occipital cortical locations were recorded while healthy participants (N = 39) viewed and imagined scenes with negative or neutral emotional valence. Self-report behavioral assessments of baseline vividness of visual …
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Investigating mechanisms of hemodynamic control in the brain
… changes in blood flow, collectively known as the hemodynamic response, that are detected by modern neuroimaging techniques such as functional magnetic resonance imaging (fMRI). Intact neurovascular coupling is imperative to neural health as de-coupling of neural activity from blood flow …
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Validation of statistical methods used in task fMRI studies
… registration to common space, pre-whitening, hemodynamic response function modelling and multiple comparison correction. As most of these methods were introduced when fMRI was in its infancy, and were initially validated only for small datasets, it is questionable whether the current default …
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The impact of rapid transItions in mental workload in a supervisory control setting
… from low to high workload by measuring the hemodynamic response of subjects to a simulated missile defense task using functional near-infrared spectroscopy, or fNIRS. NIRS is a non-invasive neuroimaging technique that uses specific wavelengths of near-infrared light to measure concentrations …
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Spatiotemporal Dynamics of Tissue Oxygenation in Awake, Behaving Mice
… unclear if the early and late components of the hemodynamic response are differentially regulated across space and time. Here, I test the hypothesis that behavioral state differentially affects the early and late components of functional hyperemia – both spatially and temporally. Using widefield …
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Advances in MRI to probe the functional and structural network of the macaque brain
… fMRI is a neuroimaging technique sensitive to hemodynamics which is indirectly linked to neural activity. Despite the applications of diffusion MRI and fMRI in basic and clinical neuroscience, the underlying biophysical mechanisms of cerebral diffusion and the hemodynamic response remain …
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Genetically encodable calcium sensors for Magnetic Resonance Imaging
… To achieve higher amplification we leverage the hemodynamic response, which is coupled to neuronal activity through a calcium-activated enzyme, neuronal nitric oxide synthase (nNOS). We show that chemical stimulation of ectopically expressed neuronal nitric oxide synthase (nNOS) elicits an …
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Biophysical modeling of hemodynamic-based neuroimaging techniques
Two different hemodynamic-based neuroimaging techniques were studied in this work. Near-Infrared Spectroscopy (NIRS) is a promising technique to measure cerebral hemodynamics in a clinical setting due to its potential for continuous monitoring. However, the presence of strong systemic interference …
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Brain segmentation using endogenous contrast mechanism using breath holding fMRI signal for tissue characterization
… fMRI. In fMRI the BOLD signal we measure is the hemodynamic response to neuronal and vascular changes at rest or in response to a stimulus where the various tissue types will have a different response. While fMRI has been traditionally been used to detect and identify eloquent regions of the …
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Statistical methods for fMRI data analysis
… method for simultaneous activation detection and hemodynamic response function (HRF) estimation; in the second part, we propose a model based clustering method to detect the functional connectivity network; in the third part, we present a general and novel statistical framework for robust and more …
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Engineered metalloproteins as contrast sensors for molecular fMRI
… day functional MRI (fMRI) measures the delayed hemodynamic response that is indirectly associated with neural activity. To study underlying molecular systems noninvasively but precisely, tools must be developed to modulate MRI contrast as a function of discrete molecular events within pathways …
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Detection power, temporal response, and spatial resolution of IRON fMRI in awake, behaving monkeys at 3 Tesla
… characterize the detection sensitivity, temporal response, and spatial resolution of IRON contrast for fMRI within the awake, behaving monkey. Understanding these issues provides insights into the physiology of the functional response to local changes in brain activity, enables researchers to …
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Development of diffusive optical imaging as a tool for studying the neurobiology of birdsong
… prototyping technology and applied it to record responses to presentations of birdsong in isoflurane-anesthetized zebra finches. We discovered a subtle but significant difference between the hemoglobin spectra of zebra finches and mammals which has a major impact in how hemodynamic responses are …
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Computational models of cardiovascular response to orthostatic stress
The cardiovascular response to changes in posture has been the focus of numerous investigations in the past. Yet despite considerable, targeted experimental effort, the mechanisms underlying orthostatic intolerance (OI) following spaceflight remain elusive. The number of hypotheses still under …
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Mothers’ neural response to valenced infant interactions predicts postnatal depression and anxiety
… unknown whether differences in mothers’ brain response can be accounted for by effects of past episodes, or if current neural processing of her child may serve as a risk factor for development of future symptoms. Twenty-four mothers from a community-based sample participated in an fMRI session …
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Methods for functional brain imaging
… for fMRI. Conventional fMRI is based on a hemodynamic response that is secondary to the underlying neuronal activation. In the final contribution of this thesis, a novel image contrast is introduced that is aimed at the direct observation of neuronal magnetic fields associated with …
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Effects of α1-receptor blockade on the hemodynamic responses to exercise in young normotensives and hypertensives
… if α1- adrenergic receptor blockade alters the hemodynamic response to exercise in young (<25 yr) male adult borderline hypertensives differently than in young normotensives. Five hypertensive (HTN, MAP>105 mmHg) and 7 normotensive (NTN, MAP<95 mmHg) college-age males underwent two 30 min bouts …
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A MATLAB-Based Subject-Specific Framework for Vessel Quantification and Localization in Longitudinal Photoacoustic Neuroimaging
… of cerebral blood vessels and the measurement of hemodynamic responses, at single vessel resolution, to neural stimulation. However, existing approaches do not provide a unified and systematic framework for consistently localizing vessels and quantifying vessel related functional responses across …
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