Bioelectrical and Neuroengineering Commons^™

Enhancing The Performance Of Brain-Computer Interfaces Via A Spatially-Aware Framework, Ahmed Ayman Eloraby

Theses and Dissertations

Electroencephalography (EEG)-based brain–computer interfaces (BCIs) provide a non-invasive pathway for communication, with the P300 speller being one of the most established paradigms. Despite its practicality, EEG signals present inherent challenges, including low signal-to-noise ratio, high dimensionality, and limited spatial resolution. These characteristics complicate the extraction of discriminative spatial patterns, which are critical for accurate P300 detection and character-level decoding.

This thesis addresses these challenges through the development of AttenPCA-Net, a deep learning framework that integrates spatially-aware processing with dimensionality reduction. Principal Component Analysis (PCA) is employed to reduce redundancy and noise while preserving the most informative components of the EEG …

Empirical Dynamical Modeling Of Cortico-Hippocampal Information Transfer During Memory Encoding, Sam Y. Cole

Theses and Dissertations

Understanding how brain dynamics support successful memory formation remains a central challenge in neuroscience. This dissertation applies tools from empirical dynamical systems theory to investigate the neural mechanisms underlying episodic encoding, with a focus on cortico-hippocampal interactions. Using stereoelectroencephalography (sEEG) data recorded during a delayed free recall of word lists task, this work reveals nonlinear, state-dependent shifts in directed information flow between cortex and hippocampus that distinguish successful from unsuccessful encoding. To further characterize these dynamics, state-space trajectories are reconstructed using time-delay embedding and recurrence-based methods, and features derived from these trajectories are used to classify memory outcomes. By integrating …

Blink-Related Brainwaves As Digital Biomarkers For Cognition Assessment During Complex Tasks, Lexine Carmlixa Sibert-Jolissaint

Theses and Dissertations

Blink-related oscillations (BROs) are neurophysiological responses observed in electroencephalography (EEG) following spontaneous blinking, reflecting the brain processing of new visual information. Prior research has demonstrated BRO responses across various cognitive states, such as resting, cognitive loading, and sensory stimulation, highlighting their potential as a non-invasive biomarker of brain function. We conducted the first investigation of BRO responses during a verbal fluency (VF) task, which is a complex, dynamic task state combining memory, visual perception, executive function, and language processing. Using publicly available EEG data from 22 healthy adults, we measured BRO responses over the left anterior frontal region corresponding to …

Development Of A Mediation Model Of Pain Cognition In Adult Patients With Sickle Cell Disease, Daniel M. Sop

Theses and Dissertations

Pain is a hallmark of Sickle Cell Disease (SCD), a genetic hemoglobinopathy characterized by chronic hemolytic anemia, vaso-occlusion, and organ damage. While acute vaso-occlusive crises (VOC) have been extensively studied, the mechanisms underlying chronic pain and its interplay with brain function remain unclear. This dissertation investigates the relationships between cerebral blood flow (CBF), fluid cognition, and pain sensitivity in adults with SCD, utilizing advanced imaging techniques and validated assessment tools.

Arterial spin labeling (ASL) and functional magnetic resonance imaging (fMRI) were employed to measure CBF and brain activity, respectively. Pain sensitivity was assessed using the Pain Sensitivity Questionnaire (PSQ), and …

Shape Memory Alloy Capsule Micropump For Drug Delivery Applications, Youssef Mohamed Kotb

Theses and Dissertations

Implantable drug delivery devices have many benefits over traditional drug administration techniques and have attracted a lot of attention in recent years. By delivering the medication directly to the tissue, they enable the use of larger localized concentrations, enhancing the efficacy of the treatment. Passive-release drug delivery systems, one of the various ways to provide medication, are great inventions. However, they cannot dispense the medication on demand since they are nonprogrammable. Therefore, active actuators are more advantageous in delivery applications. Smart material actuators, however, have greatly increased in popularity for manufacturing wearable and implantable micropumps due to their high energy …

Multi-Magnetic Material Transcranial Magnetic Stimulation Coils Development And Electric Field Measurement & Modeling Using Machine Learning, Mohannad Tashli

Theses and Dissertations

Transcranial Magnetic Stimulation (TMS) is a safe, effective, and non-invasive therapy for treating several psychiatric and neurological disorders. TMS is Food and Drug Administration (FDA) approved treatment and is commonly applied to patients who do not respond to medications for the treatment of clinical depression, smoking cessation, obsessive-compulsive disorder and migraine. Recently, there has been an increase in the development of electromagnetic neuromodulation techniques targeted at enhancing the effectiveness of TMS devices for the treatment of mental diseases. In TMS stimulation, focality is an important factor which determines the specificity of the pulses induced in different brain tissues. The electromagnetic …

Development Of An Automated Delivery System To Apply Copper Sulfate Crystals Using Precision Dry Fertilizer Application Technology, Kevin Charles Wise

Theses and Dissertations

The digenetic trematode, Bolbophorus damnificus, poses a substantial threat to catfish aquaculture, causing significant economic losses. Infestations lead to suppressed feed consumption, secondary bacterial infections and poor production performance. Survey data reveals widespread infestation in the in the southeastern United States. Current control strategies involve the application of a concentrated copper sulfate solution to reduce snail populations which serve as the first intermediate host of the trematode life cycle. This study aimed to improve treatment efficacy by developing a granular copper sulfate application system. A modified Gandy fertilizer applicator, equipped with a programmable control system, demonstrated accurate distribution of copper …

Computational Modeling Of Temporal Eeg Responses To Cyclic Binary Visual Stimulus Patterns, Connor M. Delaney

Theses and Dissertations

The human visual system serves as the basis for many modern computer vision and machine learning approaches. While detailed biophysical models of certain aspects of the visual system exist, little work has been done to develop an end-to-end model from the visual stimulus to the signals generated at the visual cortex measured via the scalp electroencephalogram (EEG). The creation of such a model would not only provide a better understanding of the visual processing pathways but would also facilitate the design and evaluation of more robust visual stimuli for brain-computer interfaces (BCIs). A novel experiment was designed and conducted where …

Advanced Modeling And Innovative Transcranial Magnetic Stimulation Coil Designs For The Treatment Of Neurological Disorders, Mohannad Tashli

Theses and Dissertations

Transcranial magnetic stimulation (TMS) is a safe, effective and non-invasive treatment for several mental and psychiatric disorders. TMS is an FDA approved treatment and is commonly applied to patients who do not respond to medications for the treatment of clinical depression, smoking cessation, obsessive-compulsive disorder and migraine. Recently, there has been an increase in the development of electromagnetic neuromodulation techniques targeted at enhancing the effectiveness of TMS devices for the treatment of mental diseases. In TMS stimulation, focality is an important factor which determines the specificity of the pulses induced in different brain tissues. The electromagnetic pulses must be confined …

Characterization And Decoding Of Speech Activity From Intracranial Signals, Pedram Zanganeh Soroush

Theses and Dissertations

Speech is the first and foremost means of human communication. Millions of people worldwide suffer from severe speech disorders due to neurological diseases such as amyotrophic lateral sclerosis (ALS), brain stem stroke, and severe paralysis. A speech neuroprosthesis that decodes speech directly from neural signals could dramatically improve life for these individuals. Recent studies have demonstrated that it is possible to decode and synthesize various aspects of acoustic speech directly from intracranial measurements of electrophysiological brain activity. For those who have completely lost the ability to speak, the objective is to synthesize acoustic speech directly from brain activity during imagined …

Innovative Techniques Of Neuromodulation And Neuromodeling Based On Focal Non-Invasive Transcranial Magnetic Stimulation For Neurological Disorders, Ivan C. Carmona-Tortolero

Theses and Dissertations

This dissertation aims to develop alternative technology that improves the current range of application of transcranial magnetic stimulation (TMS), on a scale that would permit defining specific non-invasive treatments for Parkinson’s disease and other neurological disorders. This is accomplished through three specific objectives. 1) The design of a neurostimulation system that increases the focality in TMS to regions of narrow target areas and variable depths in the brain cortex. 2) The assessment of the feasibility of novel high-frequency neuromodulation techniques that would allow increasing the focality in deeper areas beyond the cortical surface. 3) The development of a computational model …

Universal Design In Bci: Deep Learning Approaches For Adaptive Speech Brain-Computer Interfaces, Srdjan Lesaja

Theses and Dissertations

In the last two decades, there have been many breakthrough advancements in non-invasive and invasive brain-computer interface (BCI) systems. However, the majority of BCI model designs still follow a paradigm whereby neural signals are preprocessed and task-related features extracted using static, and generally customized, data-independent designs. Such BCI designs commonly optimize narrow task performance over generalizability, adaptability, and robustness, which is not well suited to meeting individual user needs. If one day BCIs are to be capable of decoding our higher-order cognitive commands and conceptual maps, their designs will need to be adaptive architectures that will evolve and grow in …

Estimating Affective States In Virtual Reality Environments Using The Electroencephalogram, Meghan R. Kumar

Theses and Dissertations

Recent interest in high-performance virtual reality (VR) headsets has motivated research efforts to increase the user's sense of immersion via feedback of physiological measures. This work presents the use of electroencephalographic (EEG) measurements during observation of immersive VR videos to estimate the user's affective state. The EEG of 30 participants were recorded as each passively viewed a series of one minute immersive VR video clips and subjectively rated their level of valence, arousal, dominance, and liking. Correlates between EEG spectral bands and the subjective ratings were analyzed to identify statistically significant frequencies and electrode locations across participants. Model feasibility and …

Effect Of Stimulus Waveform On Transcranial Magnetic Stimulation Metrics In Proximal And Distal Arm Muscles, Christopher Lynch

Theses and Dissertations

Objectives: The purpose of this study was to determine the effect of common transcranial magnetic stimulation (TMS) waveforms (monophasic and biphasic) on resting motor threshold (RMT), active motor threshold (AMT), and motor evoked potential (MEP) amplitudes in the biceps and first dorsal interosseous (FDI) because waveforms may affect motor targets differently. Additionally, we determined the test-retest reliability of TMS metrics for each stimulation type and muscle.

Methods: Ten individuals participated in two sessions of single-pulse TMS delivered to the motor cortex perpendicular to the central sulcus. MEPs were normalized to the maximum EMG signal during contraction and were recorded at …

Intermittent Theta Burst Stimulation: Application To Spinal Cord Injury Rehabilitation And Computational Modeling, Neil Mittal

Theses and Dissertations

Loss of motor function from spinal cord injuries (SCI) results in loss of independence. Rehabilitation efforts are targeted to enhance the ability to perform activities of daily living (ADLs), but outcomes from physical therapy alone are often insufficient. Neuromodulation techniques that induce neuroplasticity may push the limits on recovery. Neuromodulation by intermittent theta burst transcranial magnetic stimulation (iTBS) induces neuroplasticity by increasing corticomotor excitability, though this has most frequently been studied with motor targets and on individuals not in need of rehabilitation. Increased corticomotor excitability is associated with motor learning. The response to iTBS, however, is highly variable and unpredictable, …

Evaluating Neuromuscular Function Of The Biceps Brachii After Spinal Cord Injury: Assessment Of Voluntary Activation And Motor Evoked Potential Input-Output Curves Using Transcranial Magnetic Stimulation, Thibault Roumengous

Theses and Dissertations

Activation of upper limb muscles is important for independent living after cervical spinal cord injury (SCI) that results in tetraplegia. An emerging, non-invasive approach to address post-SCI muscle weakness is modulation of the nervous system. A long-term goal is to develop neuromodulation techniques to reinnervate (i.e. resupply nerve to) muscle fiber and thereby increase muscle function in individuals with tetraplegia. Towards this goal, developing monitoring techniques to quantify neuromuscular function is needed to better direct neurorehabilitation. Assessment of voluntary activation (VA) is a promising approach because the location of the stimulus can be applied cortically using transcranial magnetic stimulation (TMS) …

Fetal Evoked Responses: Improved Attenuation Of Cardiac Interference And Verification By Magnetic Dipole Fitting, Neslihan Bisgin

Theses and Dissertations

Early detection of fetal neurological disorders is of significant importance however, accessing the fetal brain signal has been a challenging issue. With highly sensitive Superconducting Quantum Interference Device (SQUID) sensors, fetal magnetoencephalography (fMEG) can be recorded and there have been many studies on understanding fetal brain activity through fMEG. The major problem about fMEG data is its low signal to noise ratio. fMEG is extracted from the mixture of maternal heart, fetal heart, fetal brain, and other biological signals from mother and the fetus. Effective removal of interferences is crucial in detecting the low amplitude fetal neurological signals. The objective …

The Effect Of Intermittent Theta Burst Stimulation On Biceps Corticomotor Excitability In Non-Impaired Individuals And Individuals With Tetraplegia, Blaize Majdic

Theses and Dissertations

Neuromodulation of the primary motor cortex (M1) in pair with physical therapy may be a promising method for improving motor outcomes after spinal cord injury (SCI). Increased excitability of the corticospinal motor pathways (i.e. corticomotor excitability) has shown to be associated with improved motor learning and skill acquisition. Intermittent theta burst stimulation (iTBS) is a form of non-invasive brain stimulation which can increase corticomotor excitability, as measured by an increase in the amplitude of motor evoked potentials (MEPs). However, the ability for iTBS to increase the corticomotor excitability of proximal muscles such as the biceps, and muscles affected by spinal …

Design And Testing Of An Agonist-Antagonist Position-Impedance Controlled Myoelectric Prosthesis, Christopher Aymonin

Theses and Dissertations

Intuitive prosthetic control is limited by the inability to easily convey intention and perceive physical requirements of the task. Rather than providing haptic feedback and allowing users to consciously control every component of manipulation, relegating some aspects of control to the device may simplify operation. This study focuses on the development and testing of a control scheme able to identify object stiffness and regulate impedance. The system includes an algorithm to detect the apparent stiffness of an object, a proportional nonlinear EMG control algorithm for interpreting a user’s desired grasp aperture, and an antagonistically acting impedance controller. Performance of a …

Development Of Novel Models To Study Deep Brain Effects Of Cortical Transcranial Magnetic Stimulation, Farheen Syeda

Theses and Dissertations

Neurological disorders require varying types and degrees of treatments depending on the symptoms and underlying causes of the disease. Patients suffering from medication-refractory symptoms often undergo further treatment in the form of brain stimulation, e.g. electroconvulsive therapy (ECT), transcranial direct current stimulation (tDCS), deep brain stimulation (DBS), or transcranial magnetic stimulation (TMS). These treatments are popular and have been shown to relieve various symptoms for patients with neurological conditions. However, the underlying effects of the stimulation, and subsequently the causes of symptom-relief, are not very well understood. In particular, TMS is a non-invasive brain stimulation therapy which uses time-varying magnetic …

Electrophysiology Of Basal Ganglia (Bg) Circuitry And Dystonia As A Model Of Motor Control Dysfunction, Deepak Kumbhare

Theses and Dissertations

The basal ganglia (BG) is a complex set of heavily interconnected nuclei located in the central part of the brain that receives inputs from the several areas of the cortex and projects via the thalamus back to the prefrontal and motor cortical areas. Despite playing a significant part in multiple brain functions, the physiology of the BG and associated disorders like dystonia remain poorly understood. Dystonia is a devastating condition characterized by ineffective, twisting movements, prolonged co-contractions and contorted postures. Evidences suggest that it occurs due to abnormal discharge patterning in BG-thalamocortocal (BGTC) circuitry. The central purpose of this study …

Modification And Evaluation Of A Brain Computer Interface System To Detect Motor Intention, Christopher V. Hagerty-Hoff

Theses and Dissertations

It is widely understood that neurons within the brain produce electrical activity, and electroencephalography—a technique used to measure biopotentials with electrodes placed upon the scalp—has been used to observe it. Today, scientists and engineers work to interface these electrical neural signals with computers and machines through the field of Brain-Computer Interfacing (BCI). BCI systems have the potential to greatly improve the quality of life of physically handicapped individuals by replacing or assisting missing or debilitated motor functions. This research thus aims to further improve the efficacy of the BCI based assistive technologies used to aid physically disabled individuals. This study …

An Objective Assessment Of Fetal Neurological Maturation Based On The Co-Variation Of Brain And Heart Rate Patterns, Srinivasan Vairavan

Theses and Dissertations

An in-utero neurological assessment would aid clinicians in an early detection of fetal neurological distress. However, accessing the fetal brain signal has remained a major challenge. With the advent of Superconducting Quantum Interference Device (SQUID) technology, magnetoencephalogram (MEG), is now an established technique for recording human brain activity. This technique is non-invasive and records the magnetic fields corresponding to electric currents generated by the neurons in the brain. Based on MEG technology, a first-of-a-kind device, named SARA (SQUID Array for Reproductive Assessment), was specifically designed and installed in the Department of Obstetrics and Gynecology, University of Arkansas for Medical Sciences, …

Fetal Breathing Movement And Its Distinctive Characteristics In Bio-Magnetic Data, Umit Deniz Ulusar

Theses and Dissertations

Magnetoencephalography (MEG) is widely used to study magnetic fields generated by the electrical activity of the human brain and can also be applied for fetal neurological health assessment. The fetal MEG (fMEG) signals are often contaminated with other bio-magnetic signals such as fetal breathing movement (FBM), which acts as an interfering factor for fetal neurological signals. This study was carried out to identify the bio-magnetic signals pertinent to the FBM. The fMEG signals were captured using superconducting quantum interference devices (SQUIDs) and the FBMs were recorded by an ultrasound-based video technique. The simultaneous recording is challenging since SQUIDs are extremely …

Biological System Impedance Identification Using Stochastic Estimation And Control, Enrique Mendezaceves

Theses and Dissertations

In an effort to find a less invasive way of testing for different cell abnormalities and finding more practical tests for different cellular mutations, this project makes use of a well-known technique called cellular impedance spectroscopy coupled with stochastic estimation. Impedance spectroscopy, the measurement of the complex resistance of a biological body, is not a new technology; it has been around for many years and has been used to make electrical representations of different biological systems. The problem with this procedure is that models cannot be used for system identification. Stochastic estimation can complement a model produced by analyzing the …

The Afit Multielectrode Array For Neural Recording And Simulation: Design, Testing, And Encapsulation, James R. Reid Jr

Theses and Dissertations

A two-dimensional, X-Y addressable, multiplexed array of 256 electrodes (16 x 16) has been fabricated using conventional semiconductor processing techniques. The individual electrodes are 16O microns x 160 microns, approximating the size of the cortical columns; the overall array size is 3910 microns x 3910 microns. The array has been fitted to a chronically implantable package and tested for several days in a simulated neural environment. EEG-like data were collected successfully from individual electrodes in the array. This array improves on a previous design of a 16 electrode (4 x 4) array that was chronically implanted on the cortex of …

A Topographical Analysis Of The Human Electroencephalogram For Patterns In The Development Of Motion Sickness, George S. Vogen

Theses and Dissertations

A topographical analysis was performed on 12 electroencephalograms (EEGs) collected from 10 volunteers who experienced motion sickness through cross-coupled Coriolis stimulation. Seven males and three females participated in the research conducted at the Air Force Institute of Technology, Wright- Patterson AFB. Two male volunteers participated in double-blind placebo/ phenytoin trials. Static brain maps and dynamic EEGs which focused on delta (below 3Hz) activity during the development of motion sickness revealed a seizure-like propagation pattern. With initial symptoms, a clear left parietal focus was seen in all records. A less dominant left fronto-temporal focus was present in 11 of the 12 …