patoorio wrote:I want to have a NetStim that delivers random pulses but with a variable mean interval.

You need to find or create an algorithm that does what you want.

Consider a very simple problem: you have a simulation with fixed time step dt, and you want pulses that occur at an average interval of 2*dt. One way to do this is:

at every new time step:

pick a number from the uniform distribution over [0,1]

if the number is <=0.5, generate a pulse

To generalize, suppose you want an average interval of N*dt, where N>1. You could do this by:

at every new time step

pick a number from the uniform distribution over [0,1]

if the number is <=1/N, generate a pulse.

To generalize even further, suppose you want the average interval to vary with time. This means that N must be a function of time

N = f(t) where f is always >=1

So at every new time step,

pick a number from the uniform distribution over [0,1]

if the number is <= 1/f(t), generate a pulse.

This will generate pulses whose instantaneous average interval (discoverable by averaging results of an ensemble of simulations) is f(t)*dt

And it will have to be implemented with a mod file.