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| 3. Repeat the simulations described in the previous problem (HW #2.2), but this time examine the magnitude of the underlying membrane potential oscillations by blocking spike activity in your model. An easy way to accomplish this is by setting the voltage threshold VTHR to a large value (e.g., 999 mV). You can think of this as simulating pharmacological blockade of sodium channels by application of tetrodotoxin (TTX). |
| (a) Plot "membrane potential vs. time" for all seven stimulus frequencies. Your graph should look similar to the attached plot. |
| (b) Now generate a plot of "peak depolarization vs. stimulus frequency" (HINT: you can use the MATLAB max function to find the largest value in a vector). Plot your results on a semilog axis as before. Your graph should look similar to the attached plot. Discuss how the rolloff in peak depolarization with increasing stimulus frequency is related to the rolloff in total spike count observed in the previous problem. |