Corey Klein & Nicole SztokmanCollege of CharlestonCharleston, SC

Cathy Morris & Harold Lecar (1981) [1]

Giant muscle fiber [1]

Two dimensional reduced excitation model [1]

Type 1 cell which fires in response to scale-free depolarizing stimuli [5]

“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]

Sig = sigma or standard deviation of the external Gaussian noise

Karl Friedrich Gauss [4]

Faisal, Selen, and Wolpert: Noise in the nervous system [2]

Random disturbances of signals noise is introduced at all stages of the

sensorimotor loop, from the level of a single signalling protein to that of body movement

Noise in Hodgkin-Huxley model [3

noise-induced changes in the rhythmic firing activity

type 2 excitability noise does not always have an excitatory or

positive effect can lead to inhibitory or negative effects

Impact of noise level on average firing period

Determine whether the cells burst

Morris-Lecar code: Dr. Oprisan Iapp is constant (50) Sig = 0, 10, 20, 30, etc. to 90 Measured time intervals between peaks

(ms) Averaged intervals and obtained standard

deviations Excel was used to calculate the averages,

standard deviations, and to plot the graphs

Snapshots of XPP were taken with CaptureMe Photos

45.4049 ms

36.1751 ms

28.4045 ms

16.2434 ms

1.7406 ms

1.957 ms

1.2139 ms

0.9422 ms

0.6866 ms

0.9159 ms

As noise level increases, the firing period decreases as does the standard deviation

Interestingly, the ratio of standard deviation to firing period increases with the increase in noise level.

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 %.

[1] http://www.scholarpedia.org/article/Morris-Lecar_model [2]http://www.ncbi.nlm.nih.gov.nuncio.cofc.edu/pmc/articles/

PMC2631351/?tool=pmcentrez&report=abstract [3]

http://www.ncbi.nlm.nih.gov.nuncio.cofc.edu/pmc/articles/PMC2727367/?tool=pmcentrez

[4] http://www.sfu.ca/sonic-studio/handbook/Gaussian_Noise.html [5] http://arxiv.org/abs/0801.3963