Neuroscience and Neurobiology Commons^™

The Effects Of Physical Function And Genetics On Cognition And Blood Biomarkers In Individuals At-Risk For Alzheimer’S Disease And Related Dementias, Joshua Louis Gills

Graduate Theses and Dissertations

Alzheimer’s disease and related dementia (ADRD) rates are expected to triple by the year 2050. Early detection and specific mitigation efforts are warranted to blunt the alarming rate. Physical function (PF) declines with age, but higher physical function is associated with better cognitive functioning in middle-to- older age individuals. Moreover, greater physical activity (PA) is associated with better global cognition; however, Apoliporotein e4 carriers may not gain the same benefits with exercise. Additionally, plasma phosphorylated tau 217 (p-tau217) has been identified as a novel diagnostic ADRD biomarker which needs further research to examine associations with risk factors. Therefore, the aims …

The Effect Of A Mindfulness-Based Intervention On Attention And Cognitive Control As A Function Of Smartphone Notifications., Joshua D. Upshaw

Graduate Theses and Dissertations

Barriers to accessing mobile technology, particularly smartphones, have decreased substantially since the iPhone’s release in 2007, resulting in increased ownership and usage across all ages, genders, and races. Despite their ubiquity in our society, relatively little empirical work has investigated the influence of smartphones on our higher order executive functioning. Prior work has linked smartphone use with impaired cognitive control during cognitively demanding tasks, especially in heavier smartphone users. The goals of the current study were twofold. First, the study aimed to examine the effects of smartphone notifications on cognitive control and attention. And second, to determine the effects of …

The Balance Of Excitation And Inhibition And Its Influence On Cortical States And Rett Syndrome, Jingwen Li

Graduate Theses and Dissertations

Our brain consists of billions of neurons, properly coordinating to process information and realize brain functions. Among them, there are two types of neurons: excitatory neurons and inhibitory neurons. The firing of excitatory neurons increases the membrane potential of downstream neurons, and thus excites other neurons to fire. The firing of inhibitory neurons, in contrast, decreases the membrane potential of downstream neurons, and thus inhibits other neurons to fire. The interplay of excitatory and inhibitory neurons shape the spiking activity in the population. Thus, the `balance of excitation and inhibition' plays an important role in cortical processing and brain functions. …

Microfabrication And Electrochemical Characterization Of A Novel Su-8 Probe With An Array Of Individually Addressable Electrodes Suitable For Redox Cycling Experiments In Ultra-Small Volumes, Mahsa Lotfi Marchoubeh

Graduate Theses and Dissertations

Redox cycling is an electrochemical technique that utilizes closely spaced generator and collector electrodes to cycle reversible redox species between their oxidative states. With advantages in signal amplification, selectivity of species based on their electrochemical reaction mechanism, and limited or no background subtraction, this technique is well suited for selective detection of important electrochemically active molecules such as dopamine at basal or slowly changing levels.

Miniaturized medical devices have become an area of great interest for measurement of chemicals in limited volumes with low concentrations or in sensitive tissues. A probe on a polymeric SU-8 substrate with suitable dimensions and …

An Eeg Source-Space Analysis Of The Neural Correlates Underlying Self-Regulation, Stephanie M. Long

Graduate Theses and Dissertations

Self-regulation is the cognitive process of controlling our thoughts and behaviors to be aligned with our goals. This process is used in many different contexts and has been associated with contributions from several brain regions. This research aimed to investigate differences in four prefrontal areas of the brain while participants applied four different self-regulation strategies. We recorded EEG while participants (N = 132) performed three tasks which engaged each of the four self-regulation strategies: the AX-CPT task engaged proactive and reactive control, the Go/Nogo task engaged inhibitory control, and the hybrid Flanker Global/Local task engaged the resolution of response conflict. …

Investigation Of The Role Of Heparin-Binding Pocket In Amyloid Fibrils Formation Of Fgf-1, I Gusti Ayu Agung Septiari

Graduate Theses and Dissertations

Human acidic fibroblast growth factor (aFGF/hFGF-1) is one of the promising molecules to be investigated to generate an in-depth understanding of the pathological mechanism of Alzheimer's disease (AD) neurodegenerative disorder characterized by the presence of amyloid fibrils. Some in vivo and human brain tissue studies proved the correlation of high-level expression of FGF-1-induced neuroinflammation and the occurrence of AD. The presence of amyloid fibrils as a hallmark of AD can be related to the generic property of the proteins to form amyloid fibrils; High level of FGF-1, in this case, may contribute to the formation of amyloid fibrils. As a …

The Feedback-Related Negativity Is A Time-Dependent Brain Mechanism That Facilitates Aversive Learning: Implications For The Reinforcement Learning Frn Hypothesis, Eric Rawls

Graduate Theses and Dissertations

Organisms encode rewarding and aversive experiences through reinforcement learning, capitalizing on prediction errors (PEs), which adapt action strategies over time. Computational theories are explicit that PE signals should update action weights continuously over the course of a behavioral task, an important time-dependent variation that is eschewed in traditional neuroscience studies that average over large numbers of trials. I examined variation in reaction times and feedback-locked cortical activity over time as a function of PE to critically examine theories indicating that PE signals drive time-dependent learning. We recorded EEG while participants completed a novel reinforcement task that varied prediction error on …

Impact Of Excitation-Inhibition Balance/Imbalance On Dynamics Of Cortical Neural Networks, Vidit Agrawal

Graduate Theses and Dissertations

The purpose of this research is to study the implications of Excitation/Inhibition balance and imbalance on the dynamics of ongoing (spontaneous) neural activity in the cerebral cortex region of the brain.

The first research work addresses the question that why among the continuum of Excitation-Inhibition balance configurations, particular configuration should be favored? We calculate the entropy of neural network dynamics by studying an analytically tractable network of binary neurons. Our main result from this work is that the entropy maximizes at regime which is neither excitation-dominant nor inhibition-dominant but at the boundary of both. Along this boundary we see there …

The Functional Conservation Of Frazzled In Insects, Benjamin Wadsworth

Graduate Theses and Dissertations

Axons in the developing embryo receive and react to signals that direct their growth to reach target tissues at specified locations. The signal pathways that direct midline crossing of axons during embryonic development have been comprehensively examined in the past years using the Drosophila ventral nerve cord or the spinal cord as a model system. A number of these signaling mechanisms are conserved, however disparities have been found between species in general strategy or the molecular signals controlling the response of axons to guidance cues.

The Netrin-Frazzled pathway has been shown to aid in midline crossing of axons in the …

The Functional And Structural Analysis Of Drosophila Robo2 In Axon Guidance, Lafreda Janae Howard

Graduate Theses and Dissertations

In animals with complex nervous systems such as mammals and insects, signaling pathways are responsible for guiding axons to their appropriate synaptic targets. Importantly, when this process is not successful during the development of an organism, outcomes include catastrophes such as human neurological diseases and disorders. It is vital to determine the underlying causes of such diseases by understanding the development of the nervous system. There are many pathways that have been identified to play a role in this, however, we lack an understanding of how these pathways can promote such diverse outcomes in different populations of neurons. These pathways …

Feedforward And Feedback Signals In The Olfactory System, Srimoy Chakraborty

Graduate Theses and Dissertations

The conglomeration of myriad activities in neural systems often results in prominent oscillations. The primary goal of the research presented in this thesis was to study effects of sensory stimulus on the olfactory system of rats, focusing on the olfactory bulb (OB) and the anterior piriform cortex (aPC). Extracellular electrophysiological measurements revealed distinct frequency bands of oscillations in OB and aPC. However, how these oscillatory fluctuations help the animal to process sensory input is not clearly understood. Here we show high frequency oscillations in olfactory bulb carry feedforward signals to anterior piriform cortex whereas feedback from the aPC is predominantly …

A Phenomenological Study Of The Lived Experiences Of Counseling Students In A Co-Facilitated Experiential Group, Alexandra Meyers

Graduate Theses and Dissertations

Research in the fields of experiential learning, group psychotherapy, and neuroscience has supported the inclusion of the experiential group in counseling training programs due to the potential for positive impact on students’ personal and professional development (Badenoch & Cox, 2010; Denninger, 2010). Investigations exploring counseling students’ experiences of the experiential group have been primarily limited to quantitative studies, while in-depth qualitative inquiry has been minimal. Additionally, an extensive review of the literature has found there have been no qualitative studies examining experiential groups co-facilitated by a course instructor and a doctoral student. The purpose of this phenomenological study was to …

Electrophysiological Correlates Of Visual Object Category Formation In A Prototype-Distortion Task, Stephanie Marie Long

Graduate Theses and Dissertations

In perceptual learning studies, participants engage in extensive training in the discrimination of visual stimuli in order to modulate perceptual performance. Much of the literature in perceptual learning has looked at the induction of the reorganization of low-level representations in V1. However, much remains to be understood about the mechanisms behind how the adult brain (an expert in visual object categorization) extracts high-level visual objects from the environment and categorically represents them in the cortical visual hierarchy. Here, I used event-related potentials (ERPs) to investigate the neural mechanisms involved in object representation formation during a hybrid visual search and prototype …

Validity And Reliability Of A 5-Minute Web-Camera Based Eye Tracking Test To Assess Visual Memory And Cognition, Emily Bates

Graduate Theses and Dissertations

There are approximately 5.7 million Americans currently living with Alzheimer’s Disease (AD). Early detection of cognitive impairment allows for earlier treatment, potentially slowing or halting cognitive decline. A 30-min web-camera eye tracking assessment (30-min VPC) has been validated as a tool to predict AD risk. However, a shorter version would allow for greater scalability and improve user experience. The purpose of this study was to: 1) determine the validity of the 5-minute web-camera based VPC test with the 30-min test, 2) determine the test-retest reliability of the 5-min test, 3) compare the 5-minute test scores of cognitively intact adults (18-39 …

A Hidden Markov Factor Analysis Framework For Seizure Detection In Epilepsy Patients, Mahboubeh Madadi

Graduate Theses and Dissertations

Approximately 1% of the world population suffers from epilepsy. Continuous long-term electroencephalographic (EEG) monitoring is the gold-standard for recording epileptic seizures and assisting in the diagnosis and treatment of patients with epilepsy. Detection of seizure from the recorded EEG is a laborious, time consuming and expensive task. In this study, we propose an automated seizure detection framework to assist electroencephalographers and physicians with identification of seizures in recorded EEG signals. In addition, an automated seizure detection algorithm can be used for treatment through automatic intervention during the seizure activity and on time triggering of the injection of a radiotracer to …

Combining Microdialysis And Electrophysiology In Cerebral Cortex To Delineate Functional Implications Of Acetylcholine Gradients, Tazima Nur

Graduate Theses and Dissertations

The neuronal network in cerebral cortex is a dynamic system that can undergo changes in collective neural activity as the organism changes its behavior. For example, during sleep and quiet restful awake state, many neurons tend to fire together in synchrony. In contrast, during alert awake states, firing patterns of neurons tend to be more asynchronous, firing more independently. These changes in population-level synchrony are defined as changes in cortical state. Response to sensory input is state-dependent, i.e., change in cortical state can impact the sensory information processing in cortex and introduce trial-to-trial variability in response to the same repeated …

Examining The Appropriate Recovery Interval Following Maximal Exertion For Baseline Computerized Neurocognitive Testing (Cnt), Samantha Mohler

Graduate Theses and Dissertations

Background: Computerized neurocognitive testing is part of the recommended multi-faceted approach to SRC assessment. Prior research has suggested that maximal exertion negatively effects CNT test scores. Purpose: To identify the appropriate timing of the administration of CNT following maximal exertion in healthy college-aged students. Study Design: Random cross-over, repeated measures design. Methods: Participants will be administered CNT on four different visits, with at least one week between administrations. A VO2 max treadmill test will be performed before CNT administration during three of the four trials. Following the VO2 max test, participants will rest for <2 minutes (immediate), 10-minutes, or 20-minutes before taking CNT. The fourth trial, without maximal exertion preceding CNT administration, will serve as the control. All trials will be randomly-counterbalanced to negate practice effects. RESULTS: There was a significant within-subjects effect for prescribed post-exertion recovery intervals on total symptom scores (Wilks λ = .62, F [3, 23] = 4.64, p = .01, η2= .38). Total symptom scores were significantly higher at the immediate (p < .002), 10-minutes (p = .018), and 20-minutes (p = .011) post-exertion recovery intervals compared to baseline. Additionally, a significantly positive within-subjects effect for prescribed post exertion recovery was observed for processing speed (p=.009, Wilks λ = .60, F [3, 27] = 5.9, η2 = .396). No significant effect was observed for visual memory (p = .07), verbal memory (p = .06), or reaction time (p = .40). CONCLUSION: Baseline symptom scores were negatively influenced processing speed was enhanced by maximal exertion. These changes continue to be elevated 20 minutes post-exertion. Moreover, cognitive performance was not significantly impaired following maximal exercise. To obtain more accurate baseline symptom scores, and allow processing speed composites to return to normal, sports medicine professionals should wait at least 20 minutes following maximal exertion before administering CNT.

Examining The Relationship Between State Anxiety And Vestibular And Ocular Motor Impairments And Symptoms In High School Athletes With Concussion, Mallory Kathleen Mcelroy

Graduate Theses and Dissertations

Anxiety has been associated with vestibular and ocular motor impairment in the general population. However, there is limited research regarding the connection between the vestibular and ocular motor systems and anxiety following sport-related concussion (SRC). OBJECTIVE: The purpose of this study is to compare state anxiety between concussed adolescent male and female athletes with and without vestibular and ocular motor impairments and symptoms. DESIGN: Prospective, repeated measures SUBJECTS: Thirty adolescent athletes between the ages of 15-18 years, diagnosed with a SRC completed the STAI-State at initial and medical clearance clinical visit. These adolescent athletes were categorized into vestibular and ocular …

Comparing Before-And After-School Neurocognitive Performance In High School Athletes- Implications For Concussion Management, Morgan Anderson

Graduate Theses and Dissertations

There are several factors that influence computerized neurocognitive testing performance however, one factor that has not been examined is the potential deleterious effects of cognitive fatigue from an academic school day combined with time of computerized neurocognitive testing (CNT) administration. The primary purpose of this study was to compare before-and after-school CNT performance and total symptoms in non-concussed high school student athletes. The secondary purpose of this study was to compare before-school and after-school CNT performance and total symptoms and chronotypes in non-concussed student athletes. A crossover design was used to compare before-and after-school CNT performance and total symptoms of …

Central Role Of Vasotocin In The Neuroendocrine Regulation Of Stress Responses And Food Intake In Chickens, Gallus Gallus, Gurueswar Nagarajan

Graduate Theses and Dissertations

It is well known that arginine vasotocin (AVT) in birds is involved in physiological homeostasis such as cardiovascular, osmotic regulation as well as reproductive functions. Pertinent to these physiological functions, AVT immunoreactive (-ir) neurons in the hypothalamus have been found associated with hemorrhage, dehydration, oviposition and other physiological regulation. Evidence, however, suggests that AVT also plays significant roles in modulating behavior, memory, stress, and food intake. This dissertation research addresses the latter two neuroendocrine functions of AVT in detail within the chicken brain. First, the functional role of AVT-ir neurons in conjunction with corticotropin releasing hormone (CRH)-ir neurons in the …

Examining Fear Of Re-Injury In High School Athletes With Sport-Related Concussion, Melissa Nicole Anderson

Graduate Theses and Dissertations

Recent consensus statements have advocated for research on the emotional sequelae that is associated with sport-related concussion (McCrory et al., 2012). However, changes in fear of re-injury throughout SRC recovery are understudied. The purpose of this study was two-fold: 1) to describe fear of re-injury in high school athletes with SRC, and 2) to document changes in fear of re-injury throughout SRC recovery. This study addressed several exploratory questions regarding fear of re-injury in high school athletes with SRC that pertain to identifying predictors of fear of re-injury as well as examining the relationship between fear of re-injury and locus …

Exploring The Production Of Extracellular Matrix By Astrocytes In Response To Mimetic Traumatic Brain Injury, Addison Walker

Graduate Theses and Dissertations

Following injury to the central nervous system, extracellular modulations are apparent at

the site of injury, often resulting in a glial scar. Astrocytes are mechanosensitive cells, which can create a neuroinhibitory extracellular environment in response to injury. The aim for this research was to gain a fundamental understanding of the affects a diffuse traumatic brain injury has on the astrocyte extracellular environment after injury. To accomplish this, a bioreactor culturing astrocytes in 3D constructs delivered 150G decelerations with 20% biaxial strain to mimic a traumatic brain injury. Experiments were designed to compare the potential effects of media type, number of …

Recognition Training For Faces Across Age Gaps, William Blake Erickson

Graduate Theses and Dissertations

Face recognition is a problem that has theoretical and applied value. However, the fact of facial aging is rarely addressed in research and unmentioned in the major theories of face recognition. Facial aging also has ramifications for missing persons and fugitive cases, confounding attempts by law enforcement to recover these people whose last known images are years or decades out of date. This dissertation reports three studies aimed at measuring baseline age-gap recognition ability and testing various training regimens designed to increase accuracy rates for this unique kind of recognition task.

An Investigation Of Short-Term Plasticity In Human Motor Cortex, Matthew Alan Gannon

Graduate Theses and Dissertations

Transcranial magnetic stimulation (TMS) produces a transient magnetic field that activates underlying cortical tissue by eliciting an electrical discharge of the neurons in the targeted area. Repetitive TMS (rTMS) uses patterns of repetitive TMS pulses and has been reliably shown to produce changes in the state of cortical excitability outlasting the time of stimulation. One such protocol that has demonstrated states of increased excitability is intermittent theta burst stimulation (iTBS). This method applies high-frequency bursts (50Hz) of pulses every 200 ms in trains of ten bursts. The effects of and differences between rTMS protocols have been investigated since gaining popularity …

Experimental And Computational Studies Of Cortical Neural Network Properties Through Signal Processing, Wesley Patrick Clawson

Graduate Theses and Dissertations

Previous studies, both theoretical and experimental, of network level dynamics in the cerebral cortex show evidence for a statistical phenomenon called criticality; a phenomenon originally studied in the context of phase transitions in physical systems and that is associated with favorable information processing in the context of the brain. The focus of this thesis is to expand upon past results with new experimentation and modeling to show a relationship between criticality and the ability to detect and discriminate sensory input. A line of theoretical work predicts maximal sensory discrimination as a functional benefit of criticality, which can then be characterized …

Disentangling Embodied Cognition: An Examination Of The State, Problems, And Possibilities Of Embodied Cognition, Cody Cash

Graduate Theses and Dissertations

Embodied cognition has received a fair amount of attention in philosophical, neuroscientific, and robotic research during the past several decades, yet the precise nature of its goals, methods, and claims are unclear. This dissertation will ascertain and examine the primary themes in the field of embodied cognition as well as why, and if, they offer significant challenges to traditional cognitive science models. Though many theories believe they are providing accounts that should replace traditional models, to do so they will have to overcome the very difficult challenge of arguing that mental content and capabilities derived from sensorimotor activity can continue …

Spatiotemporal Fluctuations Of Olfactory Stimuli And Its Detection By An Optical Method, Mitu Chandra Acharjee

Graduate Theses and Dissertations

Olfactory processing in the mammalian brain is a highly dynamic process, yet most of the olfaction experiments have been studied primarily with static stimuli. Odors in the natural environment are transported by turbulent flow of air or water. Natural odorants have fluctuations in concentration and it changes rapidly with time. These rapid fluctuations may pose some challenges to identifying an odor; on the other hand, the variation itself may provide important clues about the odor source. The goal of this thesis project was to create a similar odorant environment like the rapid odor fluctuations encountered in nature – to meet …

A Descriptive Study Of The Use Of Neurofeedback In Counseling, Khwlah Jamil Al-Ansari

Graduate Theses and Dissertations

This study examines neuro-counseling in the mental health field and the concept of neurofeedback training (NFB) as an intervention in the counseling profession. Numbers of studies have indicated that NFB may be effective in the field of counseling. The purpose of this survey study is to explore the use of neurofeedback in the field of counseling.

Additionally, the study used a quantitative descriptive survey research method and descriptive statistics. The survey was sent to members of the American Counseling Association (ACA), and 93 professionals participated. The majority of the sample was licensed professional counselors, professionals with a degree in counseling, …

Functional Characterization Of The Arginine Vasotocin 4 Receptor (Vt4r) In Sensory Circumventricular Organs Of The Chicken Gallus Gallus, Nguiessan Alphonse Aman

Graduate Theses and Dissertations

Past studies have shown that the avian vasotocin 4 receptor (VT4R), homologous to the mammalian arginine vasopressin receptor 1a (V1aR/AVPR1A) is involved in immobilization stress. It was not known, however, whether the receptor is also associated with osmotic stress, and if so, what brain regions may be involved. Four treatment groups of chicks were used for the study. One group was subjected to 1h immobilization stress and two groups were administered intraperitoneal injection of 3 M NaCl or 0.15 M NaCl. One additional group served as controls. After 1 h, blood samples were taken for the determination of plasma levels …

The Development Of A Traumatic Brain Injury Bioreactor, Zachery Heller

Graduate Theses and Dissertations

Approximately 1.7 million Americans experience a traumatic brain injury (TBI) each year. Concussive injuries are a subset of TBI in which blows to the head cause the brain to collide against the interior of the skull. Damage to the neurons, supporting cells, and surrounding extra cellular matrix resulting from these collisions can lead to permanent physical, cognitive, and psychological impairment. We believe the prevalence and clinical significance of concussive injures warrants research investment. To study brain injury following TBI, in vivo models have been the gold standard for TBI experiments. Although a valuable research alternative, animals are expensive, raise ethical …