Biomedical Engineering and Bioengineering Commons^™

Exploration Of Stimulus Current Energy Reduction And Bifurcation Dynamics In Conductance-Based Neuron Models Using Optimal Control Theory, Michael E. Ellinger

Dissertations

Hodgkin-Huxley type conductance-based models can simulate the effect of time-varying injected stimulus currents on the neuron membrane voltage. The dynamics simulated by these model types enables investigation of the biophysical basis of neuronal activity which is fundamental to higher level function. Broadened understanding the basis of nervous system function could lead to development of effective treatment for related diseases, disorders, and the effects of trauma. In this dissertation, optimal control is used with conductance-based neuron models to develop a "Reduced Energy Input Stimulus Discovery Method." Within the method, an objective function balances two competing criteria: tracking a reference membrane voltage …

High Frequency Field Potentials Of The Cerebellar Cortex, Jonathan David Groth

Dissertations

The cerebellum plays a crucial role in motor coordination along with basal ganglia and the motor areas of the cerebral cortex. Both somatosensory and the cerebro-cerebral pathways bring in massive amounts of neural information to the cerebellum. The output of the cerebellar cortex projects to various motor cortices as well as down to the spinal cord to make its contributions to the motor function.

The origin and function of the field potential oscillations in the cerebellum, especially in the high frequencies, have not been explored sufficiently. The primary objective of this study was to investigate the spatio-temporal characteristics of high …

Piezoelectric Scaffolds For Osteochondral Defect Repair, Sita Mahalakshmi Damaraju

Dissertations

Osteoarthritis is one of the most prevalent causes of disability affecting nearly 27 million Americans. Osteoarthritis is caused when extensive damage occurs to the articular cartilage later spreading to the underlying subchondral bone, resulting in osteochondral defects. The current clinical therapies aim at regenerating the hyaline cartilage, but instead fibrocartilage forms at the osteochondral defect site, which is inferior in structure and function and fails to integrate with the surrounding tissue. A biomimetic scaffold, which can provide cues similar to the native extracellular matrix, may facilitate osteochondral defect repair. Articular cartilage and bone extracellular matrix have been shown to produce …

Monitoring Of Cerebellar Injury Using Micro Ecog Signals In Ketamine/Xylazine Treated Rats, Gokhan Ordek

Dissertations

Much of the cerebellar research has been conducted in anesthetized animals, particularly using ketamine/xylazine combination in rats, and yet the absolute impact of the anesthesia on the neural circuit remains unanswered . In the current study, spontaneous electrical activity and sensory evoked potentials from the cerebellar surface with chronically implanted, flexible-substrate, multielectrode arrays in rats were collected and analyzed with the motor cortex signals. The power spectra and the intercontact coherence plots of the spontaneous activity in the awake-quiet animals extended up to 800 Hz in the cerebellum and only up to 200 Hz in the motor cortex. Ketamine/xylazine anesthesia …

Developing An Insulin Producing Tissue Using Mouse Embryonic Stem Cells, Neha Mahendrakumar Jain

Dissertations

This thesis describes derivation of pancreatic insulin producing cells (IPCs) from mouse embryonic stem cells and development of three-dimensional (3D) engineered tissue system to provide physiologic culture conditions for IPCs. Upon using a previously established protocol, IPCs have been successfully derived from mouse embryonic stem cells and characterized in vitro . IPCs not only express classical markers of pancreatic beta cells but also exhibit glucose responsive behavior. Interestingly while deriving IPCs from mouse embryonic stem cells, islet endothelial cells have also been identified and successfully isolated from the culture. Derivation of a pure population of endothelial cells expressing specific markers …