Using a Phase Plane graph to plot V vs. I

Using the graphical user interface to build and exercise models. Includes customizing the GUI by writing a little bit of hoc.
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Using a Phase Plane graph to plot V vs. I

Post by ted »

A user wrote:
> I am having trouble finding information on how to make an IV plot (ie.
> during a run I want to plot I on the x-axis and V on the y-axis). Is
> there an easy way to do this? I tried doing this through the grapher but
> it doesn't seem to be working out.

Use a Phase Plane graph.

NEURON Main Menu / Graph / Phase Plane

A dialog window appears asking for the x axis expression.
Example: suppose you have a membrane patch that has the hh
mechanism. You want to plot v vs. ina at the middle
of the soma section, so the x axis expression is soma.ina(0.5)
Click on the Accept button and the dialog box closes,
and you will see
x-axis: soma.ina(0.5)
on the Phase Plane's canvas.

Now you need to specify the y axis variable. Click on the
Phase Plane's menu square (left upper corner of its canvas),
select Plot what?, and up pops a big symbol browser window
that asks for the name of the variable to plot. Click in
its edit field and type soma.v(0.5), then click the Accept
button. Now the Phase Plane's canvas shows a new label:

Run a simulation and then use the Phase Plane's View = plot
to rescale the axes (click on menu square, move cursor
slightly up and then over to the right to reveal the
graph's secondary menu, and select the View = plot item).
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