by Rath, William Tyler

Abstract (Summary)
Transcranial electrical stimulation (TES) appears to be an effective way to monitor the spinal cord while patients are under anesthesia. This method is sensitive to changes in the functioning of the corticospinal tracts. It is a reliable and fast indicator of the status of the spinal cord during surgery. In this research, we develop a model to describe the intracranial voltage, electric field, and activation function distributions associated with transcranial electrical stimulation. Poissons equation is utilized with boundary conditions modeled after a real human head. The models, which are a two dimensional (2D) circular volume conductor and a three dimensional (3D) spherical volume conductor, include the inhomogeneous aspects of a human head. These inhomogeneous characteristics impact the flow of current due to volume conductivity differences between the scalp, skull, cerebrospinal fluid, and the brain itself. These results for a theoretical head model show the systematic differences between 2D and 3D models which has not been examined for TES. Knowing the differences between 2D and 3D simulations allows the inference for the results of the 3D case using a 2D model, which saves time and computational resources. A comparison of the voltages, electric fields, and activation functions is examined to determine the differences between the 2D and 3D models for each quantity. Parameterizations are also performed to show the impact of the different layers of the head. The results from the potentials, electric fields, activation function and parameterization calculations are used to infer the systematic differences between 2D and 3D models. This analysis of computational models for TES has not been performed before and is beneficial to diagnosing which areas of the brain are being stimulated during TES and gives an idea of the stimulation threshold needed to achieve muscle responses via TES.
Bibliographical Information:

Advisor:Jeffery Balzer; Louis Journee; Robert Sclabassi; Mingui Sun; Donald Crammond

School:University of Pittsburgh

School Location:USA - Pennsylvania

Source Type:Master's Thesis



Date of Publication:01/31/2007

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