### How to simulate an action potential with k3.mod

The completed exercise can be run by executing k3ap.hoc

1) Run nrngui, build a single compartment, insert hh, create a IClamp, and view an hh action potential. Hopefully, this should be routine by now. Save the AP in the voltage graph by toggling "KeepLines" on and off.

2) insert the khh channel. Note: leave the hh channels inserted since we need the sodium and leak of that model. Pop up a soma parameter panel. NEURONMainMenu/Tools/DistributedMechanisms/Viewers/ShapeName and double click on "soma".

3) change gkbar_hh to 0 and rerun. Should we accept failure and quit? Remember vrest_khh.

4) Pop up a NEURONMainMenu/Tools/DistributedMechanisms/Viewers/Mechanisms(Globals)/khh panel and set vrest_khh to -65. Rerun.

5) The AP with khh isn't bad but the fit to the hh AP can be made quite a bit better by starting a multiple run fitter using the hh AP as data, setting the fitting range from the peak to the end of the AP and fitting soma.v(.5) vs t to the hh AP by varying soma.gbar_khh.

NEURON hands-on course
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