NEURON Tutorial #18

Goals: Modify Altomare's model

Specific Aims:

Notes:

Altomare's model produces Ih with a depolarized vhalf and shallower slope factor compared to Magee's data. I don't know which model is better. One thing I think worth to try is to find sets of parameters that produce Ih with similar vhalf and slope factor as in Magee's paper and see whether it can reproduce electrophysiology experiments.

  1. I tried to find alpha_0, beta_0, gamma_0, and delta_0 so the GV curve fits to Magee's data. The code is in P0_Fit.hoc. You will find values of alpha_0, beta_0, and gamma_0 are between the values of HCN1 and HCN2. Delta_0 is a little higher than both the values of HCN1 and HCN2.
  2. Since delta_0 is larger than both the values of HCN1 and HCN2 but the values of HCN1 and HCN2 are close, I assumed delta_0 is the average of the values of HCN1 and HCN2 and tried to find the best fit. P0_Fit_2.hoc contains the code to find the parameters.
  3. After simulating electrophysiology experiments, I found the time constant is about three folds slower than Magee's data. I decided to use alpha_0 and beta_0 from HCN1. Delta_0 is the average of the values of HCN1 and HCN2. A fitting process is used to find gamma_0, which is two orders different between HCN1 and HCN2. The code is in P0_Fit_3.hoc.
  4. A comparison of several models are presented in tutorial #19.