Green's Function type response

[adamimos]

Hi. I was wondering if it was possible to give an instantaneous current injection (not a hill function, but a delta function) with IClamp. Is the best I can do to set the duration of the clamp very very very low? I was also wondering how the program would deal with my setting the duration of the clamp to smaller than the time interval between steps. Thanks!

[adamimos]

After some messing around I find that any clamping duration greater than half the timestep of the simulation invokes a response. I am guessing this stems from whatever half-step method NEURON uses to approximate the differentiial equations>?

[ted]

With fixed dt integration it is a mistake to use stimuli that last less than a full time step--whether it seems to work or not, all results will be accidents of implementational details that may vary from version to version. If you want to approximate an impulse, you could choose a dt that is two or three orders of magnitude smaller than the fastest time constant in your computational model. Or you could use adaptive integration and set dt to an arbitrarily small value (may need to adjust error tolerance for accuracy/stability).