So I am trying to write a code in C++ about the cardiac excitation threshold.

I know that this excitation threshold is the shortest stimulus2 value at which it can conduct an action potential (known as the effective refractory period) at that stimulus1 value.

So my question is: In my code should I have: apply_stimulus1 for basic_cycle_length = 1000 and while you are applying this stimulus1 apply and a stimulus2 and print out the shortest value of s2 where I can have a potential? -> the way I am thinking this is apllying both stimulus simultaneously. If we say .... this is stimulus 1 and this is ,,,, stimulus2 at the end I will have ;;;;.

Or should I say when you finish applying that stimulus1 apply a stimulu2 and give me the shortest time where I get action potential? But here I will have stimulu1 .... || (meaning ends applying stimulus1) ,,,, apply stimulus2.

Is this how I am thinking it correct or I just got lost in my own thoughts and it is easier than I make it look?

My question is:

How do I get the cardiac excitation threshold using stimulus1 and stimulus2 and how can I incorporate the theory in my C++ code.

  • $\begingroup$ ok..i just wanted the biology part first so I can give it a try in C++ and then I will post in stackoverflow, if that is ok.. $\endgroup$ Oct 16 '14 at 10:42
  • 2
    $\begingroup$ Please post your question on stackoverflow.com for help in C++ programming. And you need to edit your question for more clarity. The way it is now, it is confusing. $\endgroup$ Oct 16 '14 at 10:43
  • $\begingroup$ This doesn't seem like a programming question, however, the basic point of the question is unclear. $\endgroup$
    Oct 16 '14 at 11:37
  • $\begingroup$ i just want to know how two different stimulus can create cardiac excitation threshold. As Devon replied below it would be applying stimulus1 for a certain time then wait and then apply stimulus2. So as this question is answered how can I incorporate this in my code. Is it more clear now or still confusing? $\endgroup$ Oct 16 '14 at 11:48
  • $\begingroup$ I'm not sure how this is off-topic. This is a subject covered in an intro undergrad neuroscience course. Aside from the programming aspect, I'd use a topic like this for an undergrad exam question (e.g., "design an experiment to demonstrate the concept of relative and absolute refractory periods"). This is just taking that and actually writing a program to do it. $\endgroup$
    – Devon Ryan
    Oct 16 '14 at 12:08

You wouldn't normally apply the stimuli simultaneously. The idea is to apply stimulus1, which has a given amplitude and duration, and follow that with stimulus2, which also has a given amplitude and duration, after a variable lag. You'll then see that the effective refractory period is dependent on the amplitude of stimulus2 (at least until you hit the absolute refractory period).

  • $\begingroup$ so I will proceed with the way#2 -sort of. For example apply stimulus1 for 1000msec then wait for 5msec and then apply stimulus2? But should I got backwards in time such that I can create APs at my last AP created by Stimulus1? $\endgroup$ Oct 16 '14 at 10:39
  • $\begingroup$ Yes, you'll apply stimulus1 for 1sec and then wait, say, 5msec and then do stimulus2. Keep in mind that 1 sec is probably far too long...you normally just want to stimulate a single AP afterall, not a train. I have no idea what you mean by "go backwards" in this context. $\endgroup$
    – Devon Ryan
    Oct 16 '14 at 11:30
  • $\begingroup$ i was thinking like if my variable lag is 5msec would be easier to generate an AP from 5msec decreasing to 1msec until it gets to the last AP of stimulus1 (is it clear now? :S ) also it is in 1D strand so isn't better to be a train of APs? $\endgroup$ Oct 16 '14 at 11:34
  • $\begingroup$ Ah, got it. You'll want to use a minimum lag (say 1ms or so, depending on you AP duration). Otherwise, you end up just looking at a larger stimulus, which isn't informative. By a train of APs, I don't mean an AP traveling down the compartments of your model, unless you have to elicit a train in the first compartment to get propagation. Anyway, you certainly can use a train, I just wouldn't bother without reason. I should note that the last time I used/wrote a model like this I did it with skeletal muscle, so if I'm forgetting that cardiac models should show bursts then go with the train :) $\endgroup$
    – Devon Ryan
    Oct 16 '14 at 12:05

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