N&C

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Random Stimulation of Morris-Lecar Computational Model

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N&C

  1. 1. Corey Klein & Nicole Sztokman College of Charleston Charleston, SC
  2. 2. <ul><li>Cathy Morris & Harold Lecar (1981) [1] </li></ul><ul><li>Giant muscle fiber [1] </li></ul><ul><li>Two dimensional reduced excitation model [1] </li></ul><ul><li>Type 1 cell which fires in response to scale-free depolarizing stimuli [5] </li></ul>
  3. 3. <ul><li>“ random or irregular fluctuations or disturbances which are not part of a signal […] or which interfere with or obscure a signal or more generally any distortions or additions which interfere with the transfer of information” [2] </li></ul><ul><li>Sig = sigma or standard deviation of the external Gaussian noise </li></ul><ul><li>Karl Friedrich Gauss [4] </li></ul>
  4. 4. <ul><li>Faisal, Selen, and Wolpert: Noise in the nervous system [2] </li></ul><ul><ul><li>Random disturbances of signals </li></ul></ul><ul><ul><li>noise is introduced at all stages of the sensorimotor loop, from the level of a single signalling protein to that of body movement </li></ul></ul><ul><li>Noise in Hodgkin-Huxley model [3 </li></ul><ul><ul><li>noise-induced changes in the rhythmic firing activity </li></ul></ul><ul><ul><li>type 2 excitability </li></ul></ul><ul><ul><li>noise does not always have an excitatory or positive effect </li></ul></ul><ul><ul><li>can lead to inhibitory or negative effects </li></ul></ul>
  5. 5. <ul><li>Impact of noise level on average firing period </li></ul><ul><li>Determine whether the cells burst </li></ul>
  6. 6. <ul><li>Morris-Lecar code: Dr. Oprisan </li></ul><ul><li>Iapp is constant (50) </li></ul><ul><li>Sig = 0, 10, 20, 30, etc. to 90 </li></ul><ul><li>Measured time intervals between peaks (ms) </li></ul><ul><li>Averaged intervals and obtained standard deviations </li></ul><ul><li>Excel was used to calculate the averages, standard deviations, and to plot the graphs </li></ul><ul><li>Snapshots of XPP were taken with CaptureMe Photos </li></ul>
  7. 7. <ul><li>45.4049 ms </li></ul>
  8. 8. <ul><li>36.1751 ms </li></ul>
  9. 9. <ul><li>28.4045 ms </li></ul>
  10. 10. <ul><li>16.2434 ms </li></ul>
  11. 11. <ul><li>1.7406 ms </li></ul>
  12. 12. <ul><li>1.957 ms </li></ul>
  13. 13. <ul><li>1.2139 ms </li></ul>
  14. 14. <ul><li>0.9422 ms </li></ul>
  15. 15. <ul><li>0.6866 ms </li></ul>
  16. 16. <ul><li>0.9159 ms </li></ul>
  17. 20. <ul><li>As noise level increases, the firing period decreases as does the standard deviation </li></ul><ul><li>Interestingly, the ratio of standard deviation to firing period increases with the increase in noise level. </li></ul><ul><li>In Neuroscience, linear relationships are both valuable and sought after. Plotting the ratio vs. noise results in a trend line that has a correlation coefficient = 80 %. </li></ul>
  18. 21. <ul><li>[1] http://www.scholarpedia.org/article/Morris-Lecar_model </li></ul><ul><li>[2] http://www.ncbi.nlm.nih.gov.nuncio.cofc.edu/pmc/articles/PMC2631351/?tool=pmcentrez&report=abstract </li></ul><ul><li>[3] http://www.ncbi.nlm.nih.gov.nuncio.cofc.edu/pmc/articles/PMC2727367/?tool=pmcentrez </li></ul><ul><li>[4] http://www.sfu.ca/sonic-studio/handbook/Gaussian_Noise.html </li></ul><ul><li>[5] http://arxiv.org/abs/0801.3963 </li></ul>

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