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 33 for “"brain dynamics"”.
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Tracking brain dynamics across transitions of consciousness
… a series of gradual and rapid changes in brain activity. In this thesis, I investigate computational measures applicable to the electroencephalogram to quantify the loss and recovery of consciousness from the perspective of modern theoretical frameworks. I examine three different …
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The role of noise in brain dynamics processes
… noise can be considered ubiquitous also in the brain processes. Theoretical considerations, as well as a robust experimental evidence, demonstrate its role in many phenomena occuring at different levels in neural system: for example, firing rate of neurons is not predictable by reason of their …
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Brain Dynamics When Alertness Fluctuates but Attentional Demands Persist
… and engaged. This thesis examines how the human brain functionally reorganises when alertness levels decline but attentional demands persist. We focused on sustained auditory and visual attention using functional magnetic resonance imaging (fMRI). First, we examined how sustained auditory …
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Brain dynamics of behavioral state transitions across sleep and wakefulness
… state of quiescence, namely sleep, to maintain brain function. Sleep contributes to major aspects of cognition - including mood, attention, learning, memory, and decision making - and almost all neuropsychiatric disorders are associated with altered sleep. Though this state of decreased arousal …
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A New Eye On Semantics: Probing the Spatiotemporal Brain Dynamics Underlying Natural Reading
… To achieve this, I considered dynamic brain activity with good spatio-temporal resolution as recorded by EEG/MEG as well as behaviour as recorded by eye-tracking. In my multivariate pattern analysis in EEG/MEG source space data, I found that while semantic representations show some …
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Characterization of the Intrinsic Neural Timescale Indices as a Reliable Fingerprint of Brain Dynamics
… activity over time and offer insight into the brain’s temporal hierarchy. This thesis evaluates and compares six autocorrelation-based INT metrics—AR(1) Coefficient (Autoregressive Coefficient at 1), First Zero Lag, Lag at ACF = 1/e, Sum of Positive ACFs, ACF at Half Lag, Exponential Decay …
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Discerning nonlinear brain dynamics from EEG : an application to autistic spectrum disorder in young children
… in neuroscience is that of identifying specific brain patterns characterising autistic spectrum disorder (ASD). Genetic studies, together with investigations based on magnetic resonance imaging (MRI) and functional MRI, support the idea that distinctive structural features could exist in the ASD …
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An Analysis Using State Space Global Coherence of Brain Dynamics in a Young Child Under Sevoflurane General Anesthesia
The dynamics of brain states under general anesthesia in infants are complex and exhibit significant developmental changes, particularly in the context of neurophysiological responses. Traditional EEG analysis has been valuable in tracking these changes, but there is a critical need for more …
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Computational modelling of global haemodynamics and its interaction with cerebrospinal fluid and brain dynamics with application to essential hypertension
… description of the cerebrospinal fluid (CSF) dynamics in the craniospinal cavity. Two versions of the CSF model are presented; both versions account for deforma-tions and interaction between the cerebral vasculature, brain parenchyma and CSF compartments during the cardiac cycle. The first one …
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Characterizing the Brain Dynamics and Eye Movement Behavior of Memory-Guided Saccades: a Preliminary Investigation of Distractor Influence on Memory-Guided Saccades
<p>Research has helped to shed light on the functional organization and neural mechanisms of distractors on memory-guided saccades. In our current study we have utilized eye tracking and EEG technology to simultaneously record the changes in saccadic eye movement (SEM) behavior and event-related …
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THIS IS YOUR BRAIN ON DRUGS: A MULTIMODAL NEUROIMAGING AND COMPUTATIONAL INVESTIGATION INTO THE EFFECTS OF PSYCHEDELIC TRYPTAMINES AND MDMA ON HUMAN BRAIN DYNAMICS
… their mechanisms and impacts on the human brain. In this dissertation, we first explore the acute effects of psychedelic drugs on human brain dynamics using a computational framework called network control theory. We reveal that LSD and psilocybin decrease the barriers required for …
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Algorithms for enhanced spatiotemporal imaging of human brain function
Studies of human brain function require technologies to non-invasively image neuronal dynamics with high spatiotemporal resolution. The electroencephalogram (EEG) and magnetoencephalogram (MEG) measure neuronal activity with high temporal resolution, and provide clinically accessible signatures of …
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Neural Sequences Underlying Directed Turning in C. elegans
… that combine to generate effective movement. The brain-wide organization of the circuits that integrate sensory signals to select and execute appropriate motor sequences is not well understood. Here, we characterize the architecture of neural circuits that control C. elegans olfactory navigation. …
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Tools for Mapping the Links Between Stimuli, AffectiveStates, and Behavior through Whole-Brain Imaging inZebrafish Larvae
… of behaving animals often focuses on a singular brain region. Whole-brain imaging, on the other hand, has the capacity to significantly advance our understanding of the brain's functional architecture. In this pursuit, zebrafish larvae emerge as an ideal model for whole-brain imaging due to their …
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From fMRI to fUSI: advancing large-scale brain mapping in rodents
Investigating the principles that underlie human brain function lies at the heart ofneuroscience. Among the available tools, functional magnetic resonance imaging (fMRI) has become the reference method for mapping large-scale brain activity in humans. Its non-invasive nature, high spatiotemporal …
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Cognitive flexibility and fronto-parietal control dynamics in aging
… employing integrative paradigms to investigate brain dynamics related to successful performance in attention or control-demanding situations. These control-demanding processes are broadly referred to as “executive functions,” known to heavily involve the frontal cortex. The relationship between …
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Reduced-order Adaptive Output Predictor for a Class of Uncertain Dynamical Systems: Application to EEG-Based Control of Working Memory
… any additional information on the system dynamics. In the first experiment, the predictor's ability to track the angle of a single pendulum, including additional dynamics, is evaluated using only input-output data. The second experiment targets tracking the endpoint of a rope connected to …
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Investigating brain-wide neural mechanisms using fMRI and novel tools
… behavior requires characterizing the activity dynamics of diverse brain regions and neural circuit elements. My thesis explores such dynamics to help understand brain-wide processing of rewarding and aversive stimuli relevant to decision making. My primary experimental tool is functional …
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EXPLORING PHYSIOLOGICAL, PATHOLOGICAL AND PARAPHYSIOLOGICAL BRAIN ACTIVITY ACROSS SCALES WITH SIMULTANEOUS INVASIVE AND NON-INVASIVE EEG
… (SEEG) to enhance understanding of brain electrophysiology in pathological, physiological and paraphysiological contexts. The combination of these two methods, known as "co-registration," leverages the high temporal resolution and full-brain coverage of hd-EEG with the spatial …
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Building And Validating Next-Generation Neurodevices Using Novel Materials, Fabrication, And Analytic Strategies
… in our fundamental understanding of brain function. Despite the rapid pace of technology development, significant challenges remain in realizing safe, stable, and functional interfaces between manmade electronics and soft biological tissues. Additionally, technologies that employ …
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