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Sleep quality and heart health may be affected negatively by electromagnetic fields (EMF) emitted by telecommunication devices, and a decline in sleep quality may lead to neurological disorders such as anxiety and depression. There are multiple products that claim to improve sleep quality by blocking exposure to EMF. This study aims to investigate the efficacy of one such product called “SleepGift” blanket on sleep quality and heart health. This single-blind cross-over study analyzes the sleep study data collected from healthy participants (13 to date). Participants were provided with real and sham SleepGift blankets during two blocks of the study, and their sleep quality data were recorded. Participants slept at the Sleep Research Lab using the assigned (real/sham) blanket for block 1 pre-intervention. They committed to using the blanket at home for the next 10 consecutive nights’ then, using the same blanket, slept at the lab for post-intervention recording. The same procedure was repeated for block 2 after the washout period with the other reversed (sham/real) blanket. The collected data were analyzed. The changes observed from the Wilcoxon-rank sum test in sleep quality, heart rate variability, and Katz fractal dimension of the EEG data over night have shown to be insignificant so far. The inconclusive results of the data could be due to small sample size of the study; however, one participant showed improvement and claimed to be EMF sensitive. Ideally, recruiting such participants could be extremely challenging. A larger data set is recommended to achieve robust conclusion about the efficacy of SleepGift blanket.

Functional near-infrared spectroscopy (fNIRS) is used as a non-invasive neuroimaging technique for studying the neural dynamics within the human brain. This study uses fNIRS to explore how transcranial alternating current stimulation (tACS) affects cognitive function in people with dementia including Alzheimer’s disease (AD). By measuring changes in blood oxygenation levels, fNIRS provides a valuable means to capture plausible post-treatment alterations in cerebral hemodynamics. Previous studies have shown individuals with dementia exhibit increased oxygen consumption during verbal fluency tasks. This suggested that they might require greater effort to compensate for cognitive deficits. Therefore, it is hypothesized that tACS intervention will potentially alleviate this increased oxygen consumption by enhancing cognitive function, resulting in reduced oxyhemoglobin level post-treatment amongst those who respond positively to tACS treatment. To investigate this hypothesis, this research involved a comprehensive examination of 29 individuals with dementia, who received both real (40 Hz) and sham tACS treatment in a double-blind cross-over randomized trial. Each tACS intervention was paired with cognitive exercises (CE) on a daily basis in two 30-minute sessions for four consecutive weeks (excluding weekends) (tACS+CE). To reduce treatment effects between intervention, each participant had a 2-5 month wash-out period between treatments. Study participants were assigned into two groups using their age and cognitive level as the stratification parameters. One group received real tACS first and sham second (R1S2), and the other group’s real/sham assignment was the opposite (S1R2). An eight-channel fNIRS device was utilized to measure blood oxygenation levels in the prefrontal cortex (PFC) before and after each treatment block, during a mental task (word production and subtraction tasks). The results of this work are in support of our hypothesis that patients with dementia

This research aims to propose a design and fabrication process for a novel miniaturized electrode which can be potentially exploited to record EVestG signals and ear electrical activity from the middle inner parts, including semicircular canals and otolith organs, by an extra-tympanic electrode. This thesis covers EVestG signal recording, its currently used electrode, and the associated current challenges, followed by a review of micro-fabrication techniques, including Micro Electro Mechanical Systems (MEMS) conventional fabrication techniques (sputtering), 3Dprinting micro-fabrication technologies (Stereo-lithography or SLA), and Bio-MEMS electrode fabrication for new electrodes design with their associated technical challenges. It also presents some methodologies to cope with the challenges in our design, studying their feasibility. Then, it adopts one of the presented methodologies, which seem more feasible regarding our accessible facilities and resources. The methodology was chosen for a new needle-electrode design (potentially for EVestG recording) and it was fabricated using various technologies such as air-actuation using medical balloons, Flexible Printed Circuit Board (FPCB), 3D-printing, and MEMS fabrication. The fabrication process, from basic steps to the latest developments, is reported illustratively. Finally, the performance of the designed and fabricated micro-needle electrodes from impedance against pressure variation is investigated via some in-vitro experiments. The experiments demonstrate impedance reduction of the fabricated plastic silver-sputtered SLA-3D-printed micro-needle electrodes as the pressure increases.

Synapse organisers are crucial players in synapse development and maintenance. Neurexins are the master regulators of synapse formation. They are presynaptic proteins that connect the two neurons and facilitate signal transmission. Deletion or mutations causing altered neurexin expression has been implicated in autism spectrum disorder (ASD), schizophrenia (SCZ), epilepsy, and other neurological or psychiatric disorders. In this study, I investigated a relatively understudied but well-expressed isoform of neurexin. Since neurexins are linked with ASD and SCZ, I performed a comprehensive behavioural study on a mouse model lacking the specific isoform of neurexin and littermate wildtype (WT) mice. The behavioural tests included open field test (OFT), buried food test, visual cliff test, elevated plus maze (EPM), Crawley's three-chamber test, novel object recognition (NOR), Barnes maze (BM), and contextual fear conditioning (CFC). Mice lacking the specific isoform of neurexin displayed deficits in social memory, social novelty preference, and spatial memory compared to WT mice, which are core symptoms of ASD and SCZ, but had normal object recognition memory and fear memory. In addition, both genotypes displayed normal locomotor activity, anxiety-related behaviours, visual perception, and olfaction. Thus, the results indicate that specific neurexin isoforms may contribute to regulating social behaviour and spatial memory.

Anxiety disorders have no known biomarkers, and are thus diagnosed based on symptoms. Identifying biomarkers for these disorders could help improve the accuracy of anxiety disorder diagnoses, but may be difficult because some of the deepest brain regions are implicated in anxiety. Directly measuring activity from these regions non-invasively is highly complex; however, it may be possible to indirectly measure activity in these regions with the electrophysiological technique ‘Electrovestibulography’ (EVestG). This technique records electrical activity from the ear canals with cotton tipped wire electrodes, and detects field potentials (FPs) caused by vestibular neurons. These FPs may reveal an anxiety biomarker because they are mediated by the brainstem vestibular nucleus (VN), which receives dense projections from three anxiety-implicated brainstem regions, that in turn receive projections from anxiety-implicated regions whose homologues in rodents are known to exhibit the rhythmicity of the anxiety-implicated ‘hippocampal theta rhythm’ (hTheta). Vitally, depth recording has revealed a human analogue of hTheta in the hippocampus (HPC); and Shadli et al. [1] found an anxiety process biomarker ‘goal conflict specific rhythmicity’ (GCSR) that seems to be driven by a human analogue of hTheta, in frontal electroencephalography (EEG) data, via an anxiety-related ‘Stop Signal Task’ (SST). It may therefore be possible to test whether a human analogue of hTheta entrains vestibular FPs by eliciting this analogue with the SST while recording FPs with EVestG, where altered FP firing patterns would indicate a GCSR ‘analogue.’ The current study was comprised of two experiments: an ‘EEG Experiment’ and ‘EVestG Experiment,’ where healthy volunteers (five and four, respectively) performed the SST by pressing keyboard keys in response to images on a screen while frontal EEG or EVestG data were recorded. The ‘EEG Experiment’ was aimed at partially replicating an experiment in Shadli e

Respiratory sound analysis offers critical and clear advantages for diagnosis and monitoring of respiratory disorders. Yet, the recording technology available today remains relatively undeveloped and non-specialized. Standard high-quality audio recording systems often do not capture the low-frequency spectrum of respiratory sounds; not to mention such equipment typically has high associated costs. Contributing to the issue is a lack of standardization of equipment used; hence, what follows is a large variability of the recordings and the inability to effectively compare results between different recording systems. The objective of the following presented work was to design and build an electronic audio recording device along with microphone and suitable air-chamber to be placed over the trachea or lung for capturing respiratory breathing sounds. Design objectives included maintaining a cost-effective, portable, and small form-factor for the device as well as compatibility with our team’s patented obstructive sleep apnea (OSA) diagnostic algorithms to detect for the severity of OSA during either overnight sleep or wakefulness. All desired objectives for the design were able to be realized in a compact, cost-effective, and highly accurate device. When reviewing the tracheal breathing sound recordings conducted with the device, the results identify signal content, albeit low amplitude, past 5 kHz up to 9 kHz; that indicates the previous cut-off point of many precursory studies might not have been adequate for capturing the entire characteristic features of tracheal respiratory sounds.

The integration of visual and vestibular information is an example of multisensory processing commonly applied to our daily life. The undeniable role of visual inputs in compensation, restoration, and adaptation for vestibular deficiency has been addressed in several studies. However, current literature fails to objectively measure vestibular responses following a targeted visual stimulus. In the studies of this thesis, using Electrovestibulography (EVestG), we measured participants’ vestibular activity from the ear canals in response to targeted visual stimuli, developed in immersive virtual reality (VR) environments, delivered through a head-mounted display (HMD), quantitatively and non-invasively. This dissertation consists of four sub-studies: 1. Quantifying the difference between physically (applied via a hydraulic chair)- and visually (replicas of the physical tilts designed in a VR environment)-induced vestibular responses; 2. Investigating vestibular responses to the combined and individual effects of intensity and hue of three monochromatic colored-light stimuli (blue, green, red); 3. Investigating changes in the vestibular activity when exposed to a horizontal pursuit and saccadic eye movements; and 4. Investigating vestibular responses to the visually-evoked sensation of body movement (Vection) utilizing a VR roller-coaster. Overall from the four sub-studies mentioned above, we conclude that different visual stimuli can produce a measurably different vestibular response (measured by EVestG) depending on the VR environments’ characteristics (object motion, color, etc.). As long as the applied visual stimuli do not induce a self-motion sensation, the vestibular response is generally inhibitory (sub-studies 2 and 3). Upon feeling a self-motion sensation, the vestibular response may become an excitatory response (sub-study 4). To better understand the implications of these results, future studies should address the effect of other factors in the field of view

Obstructive sleep apnea (OSA) is a prevalent yet underdiagnosed respiratory health disorder. Assessment of OSA is currently based on sleep studies that are time-consuming and expensive. Therefore, developing technologies for quick OSA screening is momentous. The upper airways (UA) structural and physiological changes alter the tracheal breathing sounds (TBS) characteristics. The main objectives of this thesis are to investigate 1) whether the differences in TBS characteristics during wakefulness and their changes from wakefulness to sleep correlate with the severity of OSA and 2) whether different feature selection and classification methods over TBS can enhance the current algorithms. Accordingly, we have implemented advanced signal processing, machine learning, and statistical techniques on TBS data of individuals with non-OSA to severe OSA recorded during wakefulness and a short period of sleep. In TBS analysis, commonly, a considerable number of features are extracted from data. A major challenge in high-dimensional data analysis is related to classification and prediction of the variables of interest by building parsimonious models and removing variables that do not add any information to our model. We evaluated and compared the performance of the Random Forest (RF) and Least Absolute Shrinkage and Selection Operator (LASSO) Regularized Logistic Regression, as non-parametric and parametric feature selection and classification approaches, respectively, for OSA screening during wakefulness. Moreover, we analyzed and compared the spectral characteristics of TBS during wakefulness and sleep, and also from wakefulness to sleep in individuals with different OSA severity levels. The main outcomes of this work are: 1) confirming our hypothesis that the TBS characteristics during wakefulness and their variations from wakefulness to sleep correlate with the OSA severity and could reveal the structural changes of UA regarding OSA and its severity in a detailed but straigh