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Bio

Paper

Michael Fierro
Saint Joseph's University

Subject Listing - Biology
Advisor: Dr. James J. Watrous

Saturday, Poster Session 6, Presentation Kiosk 4 A, Health & Fitness Center

USING SNNAP (SIMULATOR FOR NEURAL NETWORKS AND ACTION POTENTIALS) TO MODEL THE BEHAVIOR OF NETWORKED MORIS-LECAR CELLS

Using SNNAP, a 'patch' network, consisting of dimensionless Moris-Lecar type cells, was constructed. The cells within the network consist of three voltage dependent channels - calcium, potassium, and leak, each of which is controlled by a unique set of parameters. According to Morris and Lecar's 1981 journal article "Voltage Oscillations in the Barnacle Giant Muscle Fiber," muscle fibers subjected to a constant current of electrical stimulation will exhibit oscillatory behavior. The model assumes the presence of two non-inactivating conductances in the form of calcium outside of the cell and potassium on the inside. Cardiac cells, which have many similar characteristics to barnacle muscle fiber, can be represented using the same set of equations set forth by Morris and Lecar. Nine-cell networks were modeled using both patch and geometric cells. The electrical currents and behavior of the three channels in each cell of the system were analyzed over a period of 1.0 ms. The time interval between 0.2 and 0.5 ms was the focus of this research. Action potentials were generated in the geometric network that fire at 0.315 ms and reach hyperpolarization at 0.348 ms. They had a range of voltages of -56.2 mV to 30.7 mV between depolarization and hyperpolzarization. The action potentials in the patch network fire at 0.310 ms and reach hyperpolarization at 0.345 ms. The voltage range of their action potentials was -47.5 mV to 30.1 mV. Because the patch network and geometric network had nearly identical voltage and frequency characteristics within their action potentials, the simulation can be considered valid.

Saint Joseph's University
Department of Biology

Advisor: Dr. James J. Watrous, Professor, Biology, Saint Joseph's University, Philadelphia, PA