Life Sciences Commons^™

Towards Understanding And Improving Speech Processing, Sonia Yasmin

Electronic Thesis and Dissertation Repository

This dissertation explores mechanisms for understanding and improving speech processing. First, I used EEG to investigate the acoustic and semantic processing of continuous naturalistic speech masked by multi-talker babble. I found that different features of the same speech signal are reflected in different aspects of the neural tracking response, which are themselves differentially affected by noise. These findings point to a complex relationship between speech intelligibility and neural speech encoding.

Next, I systematically reviewed the current advancements in speech enhancement technologies. I find that speech enhancement algorithms are limited in their generalizability to speech-noise (i.e., babble). I demonstrate that, for …

Apigenin Alleviates Autistic-Like Stereotyped Repetitive Behaviors And Mitigates Brain Oxidative Stress In Mice, Petrilla Jayaprakash, Dmytro Isaev, Keun-Hang Susan Yang, Rami Beiram, Murat Oz, Bassem Sadek

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Studying the involvement of nicotinic acetylcholine receptors (nAChRs), specifically α7-nAChRs, in neuropsychiatric brain disorders such as autism spectrum disorder (ASD) has gained a growing interest. The flavonoid apigenin (APG) has been confirmed in its pharmacological action as a positive allosteric modulator of α7-nAChRs. However, there is no research describing the pharmacological potential of APG in ASD. The aim of this study was to evaluate the effects of the subchronic systemic treatment of APG (10–30 mg/kg) on ASD-like repetitive and compulsive-like behaviors and oxidative stress status in the hippocampus and cerebellum in BTBR mice, utilizing the reference drug aripiprazole (ARP, 1 …

The Modulation Of Lfp Characteristics In The Freely Moving Common Marmoset, William Jm Assis

Electronic Thesis and Dissertation Repository

The hippocampus is a neural structure critical for navigation. Neurons in this region, along with others, create a functional network which generates large-amplitude modulations known as local field potential (LFP) activity. Prior LFP research has predominantly used rodent animal models, however recent studies have shown that frequencies associated with navigation in other mammals do not correlate to those of the rodent. We hypothesized that LFP characteristics in the common marmoset are modulated by the speed and axis of travel of the animal. Two marmosets were placed in a free moving 3-dimensional environment where movement and neurological activity were recorded. Results …

The Importance Of Contrast Sensitivity, Color Vision, And Electrophysiological Testing In Clinical And Occupational Settings, Frances Silva

Theses & Dissertations

Visual acuity (VA) is universally accepted as the gold standard metric for ocular vision and function. Contrast sensitivity (CS), color vision, and electrophysiological testing for clinical and occupational settings are warranted despite being deemed ancillary and minimally utilized by clinicians. These assessments provide essential information to subjectively and objectively quantify and obtain optimal functional vision. They are useful for baseline data and monitoring hereditary and progressive ocular conditions and cognitive function. The studies in this dissertation highlight the value of contrast sensitivity, color vision, and cone specific electrophysiological testing, as well as the novel metrics obtained with potential practical clinical …

Survey Of How Irregularities In The Electrical System Of The Human Heart Link To Different Heart Arrhythmias, Jazmine Boloor

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis explores the circuital pathway that a signal takes within the heart throughout a full heartbeat and provides a timing analysis. It then surveys the different pathways that could arise in the electrical system of the heart, and the associated heart diseases linked to the location of each pathway. Common heart arrhythmias such as atrioventricular nodal reentrant tachycardia, atrioventricular reentrant tachycardia, atrial flutter, and atrial fibrillation are surveyed, and their pathways are analyzed. Electrocardiograms are presented to aid in understanding of the timing analysis associated with irregularity in heart function. Finally, this thesis explores an avenue of the heartbeat …

Chemosensory Processing By The Mediodorsal Thalamus., Kelly Fredericksen

Electronic Theses and Dissertations

The mediodorsal thalamus (MD) is thought to be key component of the network that processes chemosensory information to guide our consummatory choices. Previous studies show that the mediodorsal thalamus receives projections from both the piriform cortex (PC) and gustatory cortex (GC), suggesting that it may process chemosensory information from both areas. Although the mediodorsal thalamus has been shown to respond to odors detected by sniffing, it remains unknown how its neurons represent experienced odors, tastes, and odor-taste mixtures originating from the mouth. Importantly, humans and animals with mediodorsal thalamic lesions do not suffer from anosmia, but experience deficits in odor …

Gabaergic Interneurons And Prenatal Ethanol Exposure: From Development To Aging, Adelaide R. Tousley

Dartmouth College Ph.D Dissertations

Fetal Alcohol Spectrum Disorders are the most common non-genetic cause of neurodevelopmental disability worldwide. Individuals with Fetal Alcohol Spectrum Disorder experience clinical symptoms including differences in physical, cognitive and behavioral development beginning in early childhood, but continue to face challenges into adulthood. There is a critical need to examine the effects of prenatal ethanol exposure across early development, and to establish how the developmental effects of prenatal ethanol exposure may or may not progress in aging individuals. To contribute to these two areas, I asked how a binge-type prenatal ethanol exposure might affect: (1) early postnatal development of striatal neurons …

Differences In Startle And Prepulse Inhibition In Contactin-Associated Protein-Like 2 Knock-Out Rats Are Associated With Sex-Specific Alterations In Brainstem Neural Activity, Alice Zheng, Kaela E Scott, Ashley L Schormans, Rajkamalpreet Mann, Brian L Allman, Susanne Schmid

Anatomy and Cell Biology Publications

The contactin-associated protein-like 2 (CNTNAP2) gene encodes for the CASPR2 protein, which plays an essential role in neurodevelopment. Mutations in CNTNAP2 are associated with neurodevelopmental disorders, including autism spectrum disorder and schizophrenia. Rats with a loss of function mutation in the Cntnap2 gene show increased acoustic startle response (ASR) and decreased prepulse inhibition (PPI). The neural basis of this altered auditory processing in Cntnap2 knock-out rats is currently unknown. Auditory brainstem recordings previously revealed no differences between the genotypes. The next step is to investigate brainstem structures outside of the primary auditory pathway that mediate ASR and PPI, which are …

Peripheral Modulation Of Cardiac Contractions In The American Lobster, Homarus Americanus, By The Peptide Myosuppressin Is Mediated By Effects On The Cardiac Muscle Itself, Isabel Stella Petropoulos

Honors Projects

A substantial factor for behavioral flexibility is modulation — largely via neuropeptides — which occurs at multiple sites including neurons, muscles, and the neuromuscular junction (NMJ). Complex modulation distributed across multiple sites provides an interesting question: does modulation at multiple locations lead to greater dynamics than one receptor site alone? The cardiac neuromuscular system of the American lobster (Homarus americanus), driven by a central pattern generator called the cardiac ganglion (CG), is a model system for peptide modulation. The peptide myosuppressin (pQDLDHVFLRFamide) has been shown in the whole heart to decrease contraction frequency, largely due to its effects on …

Multimodal Neuron Classification Based On Morphology And Electrophysiology, Aqib Ahmad

Graduate Theses, Dissertations, and Problem Reports

Categorizing neurons into different types to understand neural circuits and ultimately brain function is a major challenge in neuroscience. While electrical properties are critical in defining a neuron, its morphology is equally important. Advancements in single-cell analysis methods have allowed neuroscientists to simultaneously capture multiple data modalities from a neuron. We propose a method to classify neurons using both morphological structure and electrophysiology. Current approaches are based on a limited analysis of morphological features. We propose to use a new graph neural network to learn representations that more comprehensively account for the complexity of the shape of neuronal structures. In …

The Ventral Hippocampus Dynamically Regulates Amygdala Encoding And Learned Fear, Matthew Richard Herbst

Dissertations (1934 -)

The nervous system has evolved a set of survival circuits optimized to respond to environmental threats. Adaptive threat responding requires learning to predict when and where a threat may occur based on available cues. Such learning depends on a distributed network of brain structures, but there is much we do not understand about how these brain areas interact to support fear memory. Addressing this gap is crucial for understanding anxiety- and fear-related disorders as dysfunction in fear learning networks is implicated in the development and persistence of pathological fear states. In my dissertation work, I used a rodent model of …

Sensorimotor Content Of Multi-Unit Activity In The Paramedian Lobule Of The Cerebellum, Esma Cetinkaya

Dissertations

Based on Center for Disease Control and Prevention report 2016, around 39.5 million people in the United States suffer from motor disabilities. These disabilities are due to traumatic conditions like traumatic brain injury (TBI), neurological diseases such as amyotrophic lateral sclerosis (ALS), or congenital conditions. One of the approaches for restoring the lost motor function is to extract the volitional information from the central nervous system (CNS) and control a mechanical device that can replace the function of a paralyzed limb through systems called Brain-Computer Interfaces (BCI).

One of the major challenges being faced in BCIs and also in general …

Spatial Representation In Postrhinal Cortex, Patrick Lachance

Dartmouth College Ph.D Dissertations

Animals rely on a variety of internal and external cues to orient themselves when navigating their environments and determining their current spatial context. Information regarding these cues enters the brain from the navigator’s first-person perspective. Information of this type is considered to be egocentric, or self-centered. However, decades of behavioral, electrophysiological, and imaging research suggest that the brain contains a rich collection of spatial representations that are unrestricted by the animal’s first-person perspective, and instead are defined relative to the surrounding environment. These representations are considered allocentric, or world-centered. Despite an abundance of promising modeling work, the specific mechanisms by …

Characterizing And Investigating The Electrophysiological Properties Of The Plastic Cricket Auditory System In Response To Cooling, Hannah Tess Scotch

Honors Projects

The auditory system of the Mediterranean field cricket (Gryllus bimaculatus) is capable of profound compensatory plasticity. Following deafferentation due to the loss of an auditory organ, the dendrites of intermediate auditory neuron Ascending Neuron 2 (AN-2) grow across the midline and functionally connect to contralateral afferents. The loss of the auditory organ can be mimicked with reversible cold-deactivation, in which cooled Peltier elements silence the auditory organ and its afferents. Though this would presumably prevent AN-2 from firing, cooling instead induces a novel firing pattern called DOPE (delayed-onset, prolonged-excitation). In this study, intracellular physiological recordings were completed before, …

Studies Of Chemosensory Responses In The Pharynx Of The Sea Lamprey (Petromyzon Marinus), Hasan Huseyin Polat

Electronic Theses and Dissertations

The sea lamprey is a basal vertebrate, and the oldest extant species with taste buds. The objective of this thesis was to study the chemosensory responses from the sea lamprey’s pharynx, which is located caudal to oral cavity and medial to seven lateral brachiopores. The pharynx contains taste buds that detect and respond to tastants to inform lampreys about gustatory factors in the environment. The location of these taste buds along the lateral surface of the pharynx was first determined using scanning electron microscopy. Then using electrophysiology, our recordings from these pharyngeal regions containing taste buds picked up responses from …

Estrogen Modulation Of Vta Dopamine Neuron Physiology And Behavioral Responsivity To Variable Social Stressors, Mary R. Shanley

Dissertations, Theses, and Capstone Projects

The behavioral output of different animals, or even the same animal in different contexts, is remarkably variable in response to the same external stimulus. This behavioral diversity is due to the complex integration of external and internal stimuli, through both neuronal and hormonal signals that selects the best behavioral response. By their nature as long-distance signaling molecules, hormones play a critical role in communicating information about internal states across the organism. Many hormones produced in the periphery target the central nervous system to modulate animal behavior, selecting for behaviors that are appropriate over behaviors that are maladaptive in that specific …

Towards Understanding The Role Of Central Processing In Release From Masking, Nima Alamatsaz

Dissertations

People with normal hearing have the ability to listen to a desired target sound while filtering out unwanted sounds in the background. However, most patients with hearing impairment struggle in noisy environments, a perceptual deficit which current hearing aids and cochlear implants cannot resolve. Even though peripheral dysfunction of the ears undoubtedly contribute to this deficit, surmounting evidence has implicated central processing in the inability to detect sounds in background noise. Therefore, it is essential to better understand the underlying neural mechanisms by which target sounds are dissociated from competing maskers. This research focuses on two phenomena that help suppress …

Cardiomyocyte Deletion Of Bmal1 Exacerbates Qt- And Rr-Interval Prolongation In Scn5a+/Δkpq Mice, Elizabeth A. Schroder, Jennifer L. Wayland, Kaitlyn M. Samuels, Syed F. Shah, Don E. Burgess, Tanya S. Seward, Claude S. Elayi, Karyn A. Esser, Brian P. Delisle

Physiology Faculty Publications

Circadian rhythms are generated by cell autonomous circadian clocks that perform a ubiquitous cellular time-keeping function and cell type-specific functions important for normal physiology. Studies show inducing the deletion of the core circadian clock transcription factor Bmal1 in adult mouse cardiomyocytes disrupts cardiac circadian clock function, cardiac ion channel expression, slows heart rate, and prolongs the QT-interval at slow heart rates. This study determined how inducing the deletion of Bmal1 in adult cardiomyocytes impacted the in vivo electrophysiological phenotype of a knock-in mouse model for the arrhythmogenic long QT syndrome (Scn5a+/ΔKPQ). Electrocardiographic telemetry showed inducing the …

Patch Clamps, Electrophysiology, And The Optimistic Future Of Neuroscience At Usu, Riley Conover-Elmer

Student Research Symposium

The Neuroscience department is a small, yet nonetheless rapidly growing field at Utah State University. While many students are encouraged to take classes from related fields such as psychology and biology, an official Bachelor's degree has not yet been published for the university. As one of those students, digging deeper into the world of neuroscience has yielded many discoveries on biology/behavior relations that go largely unnoticed by the general student population. However, in preparation for a coming Neuroscience Major, I was given the opportunity to assist Dr. Sara Freeman in preparing for a Neurophysiology Lab course in the Spring of …

Effects Of The Antidepressant Drug Vortioxetine On Ventral Pallidal Neuronal Activity, Respiration, And Heart Rate In The Rat, Piper Rogers

Theses and Dissertations

Major Depressive Disorder (MDD) is a mental illness that affects millions of people worldwide. People diagnosed with MDD are often prescribed antidepressant drugs. Most antidepressants increase levels of serotonin (5-hydroxytryptamine, 5-HT) in the synapses between neurons. Selective-serotonin reuptake inhibitors (SSRIs), one class of antidepressants, do this by inhibiting the reuptake of serotonin released into the synapse. Serotonin neurons from the brainstem raphe nuclei affect a wide range of areas throughout the brain. Among these areas is the ventral pallidum (VP), located in the basal forebrain. Citalopram, an SSRI, has been found to increase the firing rate of action potentials of …

The Effects Of Interneuron Progenitor Cell Transplantation On Network Dynamics In An Animal Model Of Mesial Temporal Lobe Epilepsy, Willie Curry

Graduate College Dissertations and Theses

Epilepsy is associated with a very high incidence of cognitive and behavioral comorbidities that are detrimental to overall quality of life. Current treatments for epilepsy,namely anticonvulsant pharmacological agents, generally increase the amount of inhibitory drive in order to counteract the hyperexcitability observed in the disorder. However, administration of these agents, while effective for 70% of epilepsy sufferers, leave a residual 30% of patients who don’t become seizure-free. The concomitant adverse side effects of anticonvulsants - these can paradoxically include increased cognitive "fog" or confusion, automatisms, and even increased number of seizures - are a great additional concern, as is the …

Network And Cellular Effects Of The Mu Opioid Receptor In Cortical Interneurons, Adrian Dutkiewicz

Graduate College Dissertations and Theses

The µ opioid receptor (µOR) exerts a powerful excitatory effect in cortical circuits and cultured neurons by promoting glutamatergic activity after binding endogenous or exogenous opioids. While most research indicates that the receptor does this by decreasing activity or output of GABAergic interneurons that inhibit glutamate-releasing Pyramidal Neurons, other experiments suggest that the µOR directly upregulates excitatory Pyramidal Neurons instead. Thus, the cellular target of cortical opioid agonists remains unclear, and the µOR’s net excitatory mechanisms are not fully understood. Consequently, utilizing electrophysiology to detect µOR responses to the specific agonist [D-Ala2, N-Me-Phe4, Gly5-ol]-Enkephalin (DAMGO) has yielded incomplete information on …

Manipulating The Perineuronal Net In The Deep Cerebellar Nucleus, Deidre E. O'Dell

Graduate Theses, Dissertations, and Problem Reports

Perineuronal nets (PNN) are a type of specialized extracellular matrix in the central nervous system. The PNN forms during postnatal development but the ontogeny of the PNN has yet to be elucidated. Studying the PNN in the rat brain may allow us to further understand the PNN’s role in development, learning, and memory. The PNN is fully developed in the deep cerebellar nuclei (DCN) of rats by post-natal day 18. By using enzymatic digestion of the PNN with chondroitinase ABC (ChABC), we studied how digestion of the PNN affects cerebellar-dependent eyeblink conditioning (EBC) and performed electrophysiological recordings from DCN neurons. …

Muscarinic Excitation Of Dopamine Neurons In The Ventral Tegmental Area Via Activation Of A Trpc-Like Cation Conductance, Yu Tzu Chen

Theses and Dissertations

Dopaminergic (DA) neurons in the ventral tegmental area (VTA) play a crucial role in reward and motivational behaviors, including the development of drug addictions. VTA DA neurons receive excitatory cholinergic inputs from the mesopontine tegmentum. Blockage of the M5 muscarinic receptor in DA neurons has been shown to attenuate drug-induced DA release and abuse-related behaviors, but the molecular mechanism is unknown. In this study, experiments were designed to identify the electrophysiological effects of muscarinic agonism in the modulation of action potential kinetics and firing patterns in VTA DA neurons of mice. Pharmacology of the muscarinic receptor-evoked current was also characterized. …

Optogenetic Interrogation Of Hippocampal Circuit Stabilization, Laurel Watkins De Jong

Theses and Dissertations

Understanding the response of excitatory and inhibitory populations to varying input is vital to understanding how a brain region transforms information. Optogenetics - the combined use of optics and genetics to control the activity of proteins, provides neuroscientists with a tool to interrogate neuronal circuits with high spatio-temporal resolution and targeted cell specificity. This thesis examines the effects of optogenetic manipulations on hippocampal circuit responses. The hippocampus is a structure required for the formation and retention of episodic memories and is comprised of anatomically distinct subregions including cornu ammonis 3 (CA3) and cornu ammonis 1 (CA1). Both regions, despite differences …

Direct Evidence Of Missing Mepsps Using Ca2-Sensor Imaging, Petar Gajic

Biological Sciences

Following an action potential in the presynaptic neuron there is evoked release of neurotransmitter into the synapse which activates ionotropic transmembrane receptors on the postsynaptic membrane that cause depolarizations in voltage that get recorded as excitatory postsynaptic potentials (EPSPs). In the absence of an action potential there is spontaneous release of neurotransmitter that postsynaptically gets recorded as miniature excitatory postsynaptic potentials (mEPSPs). According to the quantal hypothesis, postulated by Bernard Katz, the mEPSPs are allor- none changes in potential caused by a single quantum of neurotransmitter, which when added up create EPSPs. Following studies have found that these two modes …

Focal Suppression Of Epileptiform Activity In The Hippocampus By A High-Frequency Magnetic Field, Hui Ye, Vincent Chiun-Fan Chen, Jessica Helon, Nicole Apostolopoulos

Biology: Faculty Publications and Other Works

Electric current has been used for epilepsy treatment by targeting specific neural circuitries. Despite its success, direct contact between the electrode and tissue could cause side effects including pain, inflammation, and adverse biological reactions. Magnetic stimulation overcomes these limitations by offering advantages over biocompatibility and operational feasibility. However, the underlying neurological mechanisms of its action are largely unknown. In this work, a magnetic generating system was assembled that included a miniature coil. The coil was positioned above the CA3 area of mouse hippocampal slices. Epileptiform activity (EFA) was induced with low Mg2+/high K+ perfusion or with 100 µM 4-aminopyridine (4-AP). …

Mutational Analysis And Domain Characterization Of The Apolipoprotein L-1 Ion Channel, Charles M. Schaub

Dissertations, Theses, and Capstone Projects

The human innate immunity factor Apolipoprotein L-1 (APOL1) protects against Trypanosoma brucei brucei infection. Recent studies have shown recombinant APOL1 (rAPOL1) inserts into planar lipid bilayers at an acidic pH 5.6 and forms a cation-selective channel, which opens upon subsequent neutralization, pH 7.2. This corresponds with the pH changes APOL1 would encounter during endosome recycling, suggesting that APOL1 forms a pH-gated ion channel in the plasma membrane of the parasite, leading to uncontrolled ion flux and osmotic imbalance. However, structural and domain characteristics of the APOL1 channel are poorly understood, despite potential similarities to diphtheria and colicin toxins. Utilizing E. …

Divergence In Neuronal Calcium Dysregulation In Brain Aging And Animal Models Of Ad, Adam Ghoweri

Theses and Dissertations--Pharmacology and Nutritional Sciences

Neuronal calcium dysregulation first garnered attention during the mid-1980’s as a key factor in brain aging, which led to the formulation of the Ca²⁺ hypothesis of brain aging and dementia. Indeed, many Ca²⁺-dependent cellular processes that change with age, including an increase in the afterhyperpolarization, a decrease in long-term potentiation, an increased susceptibility to long-term depression, and a reduction in short-term synaptic plasticity, have been identified. It was later determined that increased intracellular Ca²⁺ with age was due to increased Ca²⁺ channel density, elevated release from intracellular Ca²⁺ stores, and decreased Ca²⁺ buffering …

Responses Of Central Pattern Generators In The American Lobster Stns To Multiple Members Of A Novel Neuropeptide Family, Benjamin Harley Wong

Honors Projects

Neuropeptides are important modulators of neural activity, allowing neural networks, such as the central pattern generators (CPGs) that control rhythmic movements, to alter their output and thus generate behavioral flexibility. Isoforms of a neuropeptide family vary in physical structure, allowing potentially distinct functional neuromodulatory effects on CPG systems. While some familial neuropeptide isoforms can differentially affect a system, others in the same family may elicit indistinguishable effects. Here, we examined the effects elicited by members of a novel family of six peptide hormone isoforms (GSEFLamides: I-, M-, AL-, AM-, AV-, and VM-GSEFLamide) on the pyloric filter and gastric mill CPGs …