Download - The Effect of the K a current on inducement of seizures Stephanie Costa Academy of Notre Dame
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The Effect of the Ka current on inducement of seizures
Stephanie CostaAcademy of Notre Dame
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Problem
Does the substitution of a Ka current, instead of a Hh current, in R15 pacemaker network
increase seizures in the brain?
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Background Information• A seizure is the result of brain cells giving off more electrical energy
than can be handled by the brain.• Abnormal electrical impulses signal a seizure, among other brain
related issues. Abnormal electrical impulses can be seen in the data because the neurons do not follow the pattern of the R15 pacemaker neuron.
• Information travels through the brain by nerve impulses, chemical and electrical signals. The information goes through one neuron, across the synapse and then to the next neuron.
• Synapses are where two neurons meet, through this junction, cells communicate with each other.
• The R15 pacemaker is the neuron that sets the rate for all of the other neurons in that network.
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Hypothesis
The Ka current will have an increased
probability of seizure occurrences than the regular Hh neuron structure, which will
not present any seizures.
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Materials
• Computer• SNNAP (Simulator for Neural Networks and
Action Potentials) computer system
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Procedure
• Build two neural networks, beginning with R 15 pacemaker neuron. One network will have a regular Hh (K channel) current and the other will have a Ka current.
• Each network will run over a course of 120 seconds.
• The conductance will be reduced from 2.0 to 1.0 at intervals of .1
• The output will be collected from each graph
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K channel Ka channel
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Variables
• Independent variable: The network that contains the Ka current
• Dependent variable: The output of the Ka current
• Controls: the Hodkin-Huxley model of the neuron
• Constants: the SNNAP program and the unaltered portions of the neuron/network
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Hh model graphs
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Hh 2.0
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Hh 1.9 Hh 1.8
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Hh 1.7 Hh 1.6
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Hh 1.5 Hh 1.4
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Hh 1.3 Hh 1.2
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Hh 1.1 Hh 1.0
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Ka model graphs
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Ka 2.0
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Ka 1.9 Ka 1.8
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Ka 1.7 Ka 1.6
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Ka 1.5 Ka 1.4
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Ka 1.3 Ka 1.2
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Ka 1.1 Ka 1.0
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Conclusion
• The hypothesis was rejected. The Ka current had a decreased probability of seizures and actually inhibited seizures until a conductance of 1.6.
• A source of error could be the number of Ka or Hh channels in the network.
• Further research could include the results of extremes in the conductance level and the results of different neurons’ conductance when altered.
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Works CitedBarnwell, L. F. S., Lugo, J. N., Lee, W. L., Willis, S. E., Gertz, S. J., Hrachovy, R. A., & Anderson, A. E.
(2009). Kv4.2 knockout mice demonstrate increased susceptibility to convulsant stimulation. Epilepsia, 50(7), 1741-1751. doi:10.1111/j.1528-1167.2009.02086.x
Brain. In Science online. Retrieved from http://www.fofweb.com/activelink2.asp?ItemID=WE40&SID=5&iPin=NS30825&SingleRecord=True
Norris, A. J., & Nerbonne, J. M. (2010, April 7). Molecular Dissection of Ia in cortical pyramidal neurons reveals three distinct components encoded by Kv4.2, Kv4.3, and Kv1.4 α-Subunit. The Journal of Neuroscience, 30(14), 5092-5101. doi:10.1523/JNEUROSCI.5890-09.2010
Panno, J. Neurons. In Science online. Retrieved from http://www.fofweb.com/activelink2.asp?ItemID=WE40&SID=5&iPin=NBCELL0008&SingleRecord=True
Sherwood, L. (2007). Principles of neural and hormonal communication. In P. Adams (Ed.), Human physiology: From cells to systems (6th ed., pp. 85-129). Thomson Brooks/Cole.
Sherwood, L. (2007). The plasma membrane and membrane potential. In P. Adams (Ed.), Human physiology: From cells to systems (6th ed., pp. 53-83). Thomson Brooks/Cole.
Simulator for Neural Networks and Action Potentials (SNNAP) (Version 8) [Computer software and manual]. (January 2003). Houston, Texas: The University of Texas-Houston Medical School.
(2008, August 18). Life Sciences; Research from National Cheng-Kung University, Department of Neurology provides new data about life sciences. Mental Health Weekly Digest, 78, Retrieved from http://elibrary.bigchalk.com