Life Sciences Commons^™

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 …

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. …

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 …

Understanding Object Motion Encoding In The Mammalian Retina., Victor Julian Depiero

Electronic Theses and Dissertations

Phototransduction, transmission of visual information down the optic nerve incurs delays on the order of 50 – 100ms. This implies that the neuronal representation of a moving object should lag behind the object’s actual position. However, studies have demonstrated that the visual system compensates for neuronal delays using a predictive mechanism called phase advancing, which shifts the population response toward the leading edge of a moving object’s retinal image. To understand how this compensation is achieved in the retina, I investigated cellular and synaptic mechanisms that drive phase advancing. I used three approaches, each testing phase advancing at a …

Data Collection Curated With An Application Ontology Describes The Methods And Results Upon Performing An Ex-Vivo Voltage-Clamp Assay On Outer Hair Cells Of The Mammalian Cochlea, Brenda Farrell, Jason Bengtson

Research Data

This data collection describes the electrical properties of outer hair cells isolated from the mammalian cochlea of the domestic guinea pig. This data was obtained by performing whole-cell patch clamp voltage clamp assay on cells and monitoring the electrical admittance during a DC voltage ramp. The membrane capacitance was then calculated at each membrane potential from this admittance, and the voltage-independent and voltage-dependent membrane capacitance was determined upon further analysis. In some case the DC conductance was also measured by interrogation of the cell with voltage-step function which was calculated from the change in the mean steady-state current with respect …

The Effects Of A Ketone Body On Synaptic Transmission, Alexandra Elizabeth Stanback

Theses and Dissertations--Biology

The ketogenic diet is commonly used to control epilepsy, especially in cases when medications cannot. The diet typically consists of high fat, low carb, and adequate protein and produces a metabolite called acetoacetate. Seizure activity is characterized by glutamate excitotoxicity and therefore glutamate regulation is a point of research for control of these disorders. Acetoacetate is heavily implicated as the primary molecule responsible for decreasing glutamate in the synapse; it is believed that acetoacetate interferes with the transport of glutamate into the synaptic vesicles. The effects on synaptic transmission at glutamatergic synapses was studied in relation to the ketogenic diet …

Cannabinoid Transmission In The Basolateral Amygdala Modulates Prefrontal Cortex And Ventral Hippocampal Activity, Brian J. Pereira

Electronic Thesis and Dissertation Repository

The cannabinoid system is important for maintaining neuron-to-neuron communication within the mammalian brain. One of the most commonly used substances to alter the cannabinoid system is cannabis. Individuals who are exposed to cannabis report having dissociable effects; both positive and negative. High amounts of THC have been commonly associated with the negative effects of cannabis, whereas CBD can be used to counter these. Pre-clinical evidence suggests that the combination of the two compounds can produce a therapeutic benefit for individuals who are susceptible to the effects of THC. The present study investigates whether the combination of THC+CBD can prevent electrophysiological …

Characterizing The Cognitive And Emotional Effects Of Delta-9-Tetrahydrocannabinol In Distinct Hippocampal Sub-Regions, Dinat Khan

Electronic Thesis and Dissertation Repository

The objective of this study is to determine the potential differential effects of THC in the DH or VH sub-regions, as well as the upstream effects on PFC neuronal activity and oscillations. Rodents used for electrophysiology were infused with THC or vehicle in the DH or VH regions, combined with PFC recordings. Additionally, a battery of behavioural paradigms was performed. Deficits in short-term memory when THC was infused into both regions was observed, however working memory was impaired with VH infusions only. This could be due to THC-induced dysregulation in the PFC, as beta oscillations were significantly decreased selectively in …

Transient Receptor Potential Cation Channel, Subfamilies V, Member 1 (Trpv1) And M, Member 1 (Trpm1) Contribute To Neural Signaling In Mouse Retina., Jennifer Noel

Electronic Theses and Dissertations

The retina processes light information through parallel pathways in order to extract and encode the visual scene. Light information is transmitted to the brain through approximately 30 ganglion cells (GCs), the retinal output neurons. Trp channels modulate the responses of retinal neurons within specific pathways. The study of the expression and function of the majority of Trp channels in the retina is largely in its infancy. My dissertation first investigated the expression and function of the transient receptor potential vanilloid-1 (TRPV1) receptor/channel in the retina. TRPV1, the first cloned and most highly studied Trp channel in the peripheral nervous system, …

Synaptic Homeostasis At The Drosophila Neuromuscular Junction: Molecular Mechanisms And Developmental Adaptation, Lindsay A. Gray

Dissertations, Masters Theses, Capstones, and Culminating Projects

No abstract available

Dopaminergic And Activity-Dependent Modulation Of Mechanosensory Responses In Drosophila Melanogaster Larvae, Josh S. Titlow

Theses and Dissertations--Biology

A central theme of this dissertation is nervous system plasticity. Activity-dependent plasticity and dopaminergic modulation are two processes by which neural circuits adapt their function to developmental and environmental changes. These processes are involved in basic cognitive functions and can contribute to neurological disorder. An important goal in modern neurobiology is understanding how genotypic variation influences plasticity, and leveraging the quantitative genetics resources in model organisms is a valuable component of this endeavor. To this end I investigated activity-dependent plasticity and dopaminergic modulation in Drosophila melanogaster larvae using neurobiological and genetic approaches.

Larval mechanosensory behavior is described in Chapter 2. …

Modulation Of Synaptic Transmission By Adenosine In Layer 2/3 Of The Rat Visual Cortex In Vitro, Nicholas M. Bannon

Master's Theses

No abstract provided.

Structural Analysis Of The Drosophila Innexin Shakb: Role Of The N-Terminus In Rectifying Electrical Synapses, William Marks

Biology Theses

Gap junction channels mediate direct intercellular communication in all multicellular animals. They are comprised of the connexin family of proteins in vertebrates and the innexin family in prechordates. Connexins and innexins share many functional and structural similarities as orthologous proteins. Both types are capable of forming electrical synapses. Rectifying junctions are specialized electrical synapses found in neural systems that control escape responses. It has been shown that heterotypic gap junction channels mediate asymmetric properties of rectifying junctions. Shaking B N+16 and Shaking B lethal are variants of the ShakB locus in Drosophila and the organization of these innexins into heterotypic …

Epilepsy-Associated Dysfunction In The Voltage-Gated Neuronal Sodium Channel Scn1a, Christoph Lossin, T. Rhodes, R. Desai, C. Vanoye, S. Caniciu, O. Devinsky, A. George

Christoph Lossin, Ph.D.

Mutations in SCN1A, the gene encoding the brain voltage-gated sodium channel subunit (Nav1.1) are associated with at least two forms of epilepsy, generalized epilepsy with febrile seizures plus (GEFS+) and severe myoclonic epilepsy of infancy (SMEI). We examined the functional properties of four GEFS+ alleles and one SMEI allele using whole-cell patch-clamp analysis of heterologously expressed recombinant human SCN1A. One previously reported GEFS+ mutation (I1656M) and an additional novel allele (R1657C), both affecting residues in a voltage-sensing S4 segment, exhibited a similar depolarizing shift in the voltage dependence of activation. Additionally, R1657C showed a 50% reduction in current density and …