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Cortical Activation During Mobility In An Indoor Real-World Environment: A Mobile Eeg Study, Sam Marshall

Electronic Thesis and Dissertation Repository

Human mobility requires neurocognitive inputs to safely navigate the environment. Previous research has examined neural processes that underly walking using mobile neuroimaging technologies, yet few studies have incorporated true real-world methods without a specific task imposed on participants (e.g., dual-task, motor demands). The present study utilized mobile electroencephalography to examine and compare theta, alpha, and beta frequency band power (μV2) in young adults during sitting and walking in laboratory and real-world environments. Our findings support that mobility and environment may modulate neural activity, as we observed increased brain activation for walking compared to sitting, and for real-world walking compared to …

Neural Dynamics Of Visual Processes In Challenging Visibility Conditions, Saba Charmi Motlagh

Electronic Thesis and Dissertation Repository

In our daily visual experience, our brain effortlessly categorizes countless objects, enabling us to perceive and interpret the world around us. This core object recognition process is vital for our survival and adaptive behavior, allowing us to recognize objects despite variations in appearance. The incredible speed at which we accomplish this task is a testament to the efficiency of our visual system and the significance of visual processing is evident in the allocation of nearly half of the neocortex in primates to this function. Unraveling the intricacies of how the human visual system tackles this complex challenge has long been …

Neural Dynamics Of Target Processing In Attentional Blink, Mansoure Jahanian

Electronic Thesis and Dissertation Repository

The attentional blink (AB) phenomenon refers to the failure to report the second target (T2) if it appears 200-500 ms after the first target (T1) in a stream of rapidly presented images. The present study aimed to investigate the neural representations of target processing under conditions where AB does or does not occur. We recorded EEG and behavioral data while participants viewed a rapid sequence of natural object images embedded with two face targets presented at two lag conditions: lag 3 (targets were 252 ms apart) and lag 7 (targets were 588 ms apart). Consistent with AB, our behavioral results …

Temporal Dynamics Of Natural Sound Categorization, Ali Tafakkor

Electronic Thesis and Dissertation Repository

While extensive research has elucidated the brain’s processing of semantics from speech sound waves and their mapping onto the auditory cortex, the temporal dynamics of how meaningful non-speech sounds are processed remain less examined. Understanding these dynamics is key to resolving the debate between cascaded and parallel hierarchical processing models, both plausible given the anatomical evidence. This study investigates how semantic category information from environmental sounds is processed in the temporal domain, using electroencephalography (EEG) collected from 25 participants and representational similarity analysis (RSA) along with models of acoustic and semantic information. We examined information extracted by the brain from …

Developmental Differences In The Learning And Consolidation Of Linguistic Regularities, Sarah Berger

Electronic Thesis and Dissertation Repository

Relative to adults, children have a well-known advantage for learning linguistic regularities, which could be partially driven by their deeper sleep. To examine the relationship between consolidation and language learning across development, children and adults learned a novel article system with an implicit grammatical rule. Participants performed a judgment task on phrases containing the novel articles before and after a night of EEG-monitored sleep. We found that rule sensitivity emerged rapidly in children, whereas it did not emerge until the second session in adults. Children demonstrated better generalization of the rule than adults. Consolidation effects showed a developmental double dissociation, …

Seizure Detection Using Deep Learning, Information Theoretic Measures And Factor Graphs, Bahareh Salafian

Electronic Thesis and Dissertation Repository

Epilepsy is a common neurological disorder that disrupts normal electrical activity in the brain causing severe impact on patients’ daily lives. Accurate seizure detection based on long-term time-series electroencephalogram (EEG) signals has gained vital importance for epileptic seizure diagnosis. However, visual analysis of these recordings is a time-consuming task for neurologists. Therefore, the purpose of this thesis is to propose an automatic hybrid model-based /data-driven algorithm that exploits inter-channel and temporal correlations. Hence, we use mutual information (MI) estimator to compute correlation between EEG channels as spatial features and employ a carefully designed 1D convolutional neural network (CNN) to extract …

Cognitive Neuroscience Of Schizophrenia: Stochastic Modelling Of Cognitive-Process Latencies And Nonlinear Dynamics Of Neuro-Signals, Colleen D. Cutler

Electronic Thesis and Dissertation Repository

We study known and potential numerical earmarks of schizophrenia through mathematical methods. One known numerical characteristic of schizophrenia is that of prolonged encoding latencies in response to cognitive stimuli. Motivated by the need to explain interaction patterns in 2 x 2 factorial data where one factor is encoding load and the other is diagnostic status, we define a class of general serial mixture models based on the number of encoding subprocesses executed and the speed at which they are executed. Mathematical derivations performed on these models yield closed form expressions for the mean encoding latency and average intertrial variance, which …

The Role Of Neural Entrainment In Statistical Learning, Jordan-Jerrica Mulgrew

Electronic Thesis and Dissertation Repository

Statistical learning (SL) refers to our ability to extract patterns from the environment. Research has long acknowledged the importance of SL in language; however, the neural mechanisms underlying SL remain largely unknown. One potential mechanism is neural entrainment, which refers to the tendency of endogenous neural oscillations to align with an ongoing rhythmic stimulus. In the context of SL, neural entrainment may align neural excitability to the ongoing structure of the speech stream, increasing sensitivity to underlying patterns and supporting the learning of word boundaries. This thesis tested the hypothesis that neural entrainment plays a causal role in SL by …

Multisensory Associative Learning And Multisensory Integration, Sebastien Lauzon

Electronic Thesis and Dissertation Repository

Human multisensory experiences with the world rely on a combination of top-down and bottom-up influences, a process that changes throughout development. The present study explored the relationship between multisensory associative learning and multisensory integration using encephalography (EEG) and behavioural measures. While recording EEG activity, participants were exposed to novel pairings of non-sociolinguistic audiovisual stimuli of varying presentation probability while performing a detection task. The same stimuli were then used in another detection task, which was followed by an analogous behavioural speeded-response task, both of which kept probabilities equal and tested for multisensory integration. Significant relationships were found in fronto-central and …

Using Meditation To Improve Measures Of Attention In Older Adults, Sabrina Ford

Electronic Thesis and Dissertation Repository

Age-related cognitive decline greatly impacts quality of life for older adults. Previous research has indicated that meditation may act as a neuroprotective factor to prevent age-related cognitive decline. This thesis sought to replicate previous findings and investigate if a four-week meditation intervention would improve sustained attention. Participants 60 years and older (n=27, 17 female) were recruited and assigned to a focused-attention (FA) meditation or relaxation group which met for four weeks, three times a week. Resting-state EEG was used to collect individual alpha peak frequency (iAPF) and frontal alpha asymmetry (FAA). The Sustained Attention to Response Task (SART) was also …

Neural Entrainment Indexes Statistical Learning In Children, Christine Moreau

Electronic Thesis and Dissertation Repository

Statistical learning is proposed as a mechanism for discovering structural patterns in speech through incidental exposure. However, studies have largely relied on assessing explicit memory after learning has occurred, which does not capture the time course and process of statistical learning per se. To better understand the dynamics of statistical learning, we assessed 8- to 12-year-old children using an EEG measure of learning, which captures changes in neural entrainment to words embedded in a continuous artificial language. Statistical learning was assessed post-learning using implicit and explicit behavioural tests. The neural entrainment results demonstrated rapid learning of word-level information, while post-learning …

Working Memory And Falls Risk In Older Adults: An Event-Related Potential Study, Yee (Michelle) S. Wong

Electronic Thesis and Dissertation Repository

BACKGROUND: The aging population is rapidly increasing, where currently in North America, the population of older adults (ages 60+) outnumbers the population of children. Falls are a major concern for older adults and their quality of life. Cognitive impairment has been shown to be declined in older adults at-risk for falls, but working memory has not been thoroughly investigated within this population. PURPOSE: To examine differences in Non-Fallers, Moderate Risk for Falls, and Fallers in a working memory task using electroencephalography (EEG). METHODS: Older adults (n=44, female=27) aged 60 – 80 years (m=68.8, SD=4.7) completed two sessions. The first session …

Neurocircuits Of Posttraumatic Stress Disorder And Its Dissociative Subtype, Andrew A. Nicholson

Electronic Thesis and Dissertation Repository

The amygdala and insula are highly implicated in the pathophysiology of posttraumatic stress disorder (PTSD), where both have been shown to be hyper/hypoactive in PTSD and dissociative subtype (PTSD+DS) PTSD patients, respectively, during symptom provocation. However, the functional connectivity of individual amygdala and insula subregions have not previously been compared in PTSD, PTSD+DS and healthy controls. In two separate studies, we examined amygdala complex (chapter 2) and insula subregion (chapter 3) functional connectivity patterns using resting-state fMRI. Patients with PTSD and PTSD+DS were found to display unique amygdala complex functional connectivity patterns to prefrontal cortex (PFC) regions involved in emotion …

The Neural Mechanisms Of Musical Rhythm Processing: Cross-Cultural Differences And The Stages Of Beat Perception, Daniel J. Cameron

Electronic Thesis and Dissertation Repository

Music is a universal human behaviour, is fundamentally temporal, and has unique temporal properties. This thesis presents research on the cognitive neuroscience of the temporal aspects of music: rhythm, beat, and metre. Specifically, this work investigates how cultural experience influences behavioural and neural measures of rhythm processing, and the different neural mechanisms (with particular interest in the role of the striatum) that underlie different stages of beat perception, as musical rhythms unfold.

Chapter 1 presents an overview of the existing literature on the perceptual, cognitive, and neural processing of rhythm, including the entrainment of neural oscillations to rhythm and the …

Event-Related Potential Markers Of Perceptual And Conceptual Speech Processes In Patients With Disorders Of Consciousness., Stephen T. Beukema

Electronic Thesis and Dissertation Repository

Vegetative state (VS) and minimally conscious state (MCS) patients behaviorally demonstrate absent or fluctuating levels of awareness. Functional magnetic resonance imaging evidence of covert perceptual and semantic speech processing provides prognostic value for these patients. In this thesis, I examined the utility of high-density electroencephalography (EEG) in this regard. A contrast between event-related potentials (ERPs) elicited by primed and unprimed word pairs was used to isolate conceptual (semantic) processes, while ERPs elicited by signal-correlated noise were contrasted with those elicited by speech to isolate pre-semantic, perceptual aspects of speech processing. These ERP effects were found to be both temporally and …

Creativity As A Mental State: An Eeg Study Of Musical Improvisation, Joel A. Lopata

Electronic Thesis and Dissertation Repository

Researchers in cognitive neuroscience have used brain-imaging methods (e.g., EEG, fMRI) to investigate the neural correlates of creative cognition and have found increased activity in the alpha frequency band (Fink et al., 2009a, 2009b; Martindale, 1975), however few studies have used neuroscientific measures to investigate artistic creativity. Such studies are valuable because they share a characteristic of ecological validity. In this study I used EEG, the Alternate Uses Test (Guilford, 1967), and the Consensual Assessment Technique (Amabile, 1982) to substantiate a conceptualization of creativity as a mental state characterized by a distinct pattern of neural activity. The participants were musicians …

Optimizing The Analysis Of Electroencephalographic Data By Dynamic Graphs, Mehrsasadat Golestaneh

Electronic Thesis and Dissertation Repository

The brain’s underlying functional connectivity has been recently studied using tools offered by graph theory and network theory. Although the primary research focus in this area has so far been mostly on static graphs, the complex and dynamic nature of the brain’s underlying mechanism has initiated the usage of dynamic graphs, providing groundwork for time sensi- tive and finer investigations. Studying the topological reconfiguration of these dynamic graphs is done by exploiting a pool of graph metrics, which describe the network’s characteristics at different scales. However, considering the vast amount of data generated by neuroimaging tools, heavy computation load and …

Investigating The Effects Of Custom Made Orthotics On Brain Forms: A Pilot Study, Lindsay Carey

Electronic Thesis and Dissertation Repository

OBJECTIVES: To determine (1) the feasibility of this novel approach and technique of recording brain activity, wirelessly and continuously, during human gait, and (2) if custom made orthotics will alter the brain activity patterns recorded. METHODS: Gait trials were performed on 16 participants walking with and without orthotic devices in their shoes while simultaneously collecting EEG data through the Emotiv wireless neuroheadset. RESULTS: The Emotiv neuroheadset was capable of detecting changes in brain activity between the two gait trials. The differences in brain activity identified between conditions were not statistically significant. CONCLUSION: The findings suggest the Emotiv EEG device is …

A P300 Based Cognitive Assessment Battery For Severely Motor-Impaired And Overtly Non-Responsive Patients, Aaron M. Kirschner

Electronic Thesis and Dissertation Repository

Diagnosing disorders of consciousness (DOC) is notoriously difficult, with estimates of misdiagnosis rates as high as 40%. Moreover, recent studies have demonstrated that patients who do not show signs of volitional motor responses can exhibit preserved command following detected by functional magnetic resonance imaging (fMRI) and electroencephalography (EEG). Although these patients clearly retain some cognitive abilities, lack of consistent motor responses makes administration of standard neuropsychological tests impossible. Consequently, the extent of their cognitive function is unknown. In the current study, we developed and validated a P300b event related potential (ERP) neuropsychological battery in healthy participants to assess components of …