Can I generate an action potential phase plot from Clampfit software? If so, how does one do it?
If not, how can one begin to produce this plot?
Hi Cody,
You can make a dV/dt vs. V action potential plot in pClamp in the following way, for example:
1. Duplicate your AP-containing trace.
2. Differentiate the duplicate (tx = diff(ty), using the arithmetic toolbox, where tx is your duplicate and ty is your original trace)
3. Analyze -> Quick Graph -> Trace vs. Trace, then set the options accordingly
Another way would be to transfer the voltage trace to a table, then create a new column with the diff'ed voltage trace, assign x and y columns and create the plot.
There are far easier scriptable methods for AP phase plot creation outside of pClamp though, in Python/Igor/R/Stimfit and others.
Hope this helps :)
Marcin
Hi Cody,
You can check out my program called NeuroExpress. It loads ABF files that were recorded in pClamp. If you stimulate the neuron using current steps, the program will calculate the phase portraits of APs. You can find it in my Researchgate page.
Best, Attila
Thank you both for your responses. They have both been very helpful.
Attila Szücs
-- I will take a look into this route as it may be the great alternative.
Marcin Siwiec
-- Thank you, I contacted tech support at Molecular devices and was able to figure this type of plot. The advice from their page mirrors yours. Thank you again.
Also, for you both: When one uses a phase plot, does it make most sense to plot a representative AP phase plot to indicate changes or can one plot average responses of the data? I found that due to the difference AP curves/responses the averages of AP response produces a mess phase plot.
Hi Cody,
It really depends on your hypothesis and data generation. However, given that dV/dt is usually pretty noisy, it would be better to average a few APs. Best to generate single APs with a large, short current step (e.g. 1-2 nA, 1-2 ms) and repeat the protocol a few times with sufficient time in between to prevent any plasticity. So for example 5-10 sweeps once every 2-3 s. Then generate the phase plot from the average AP.
Best,
Marcin
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