I would like to say once a stimuli (let's say to fire) has reached a certain treas hold the neuron will fire, no matter what happens after that. If the inputs it receives is to weak to reach this treas hold, it will not fire. If it receives opposite inputs (to fire and not fire) the same principle applies, the strongest stimuli that will make the neuron reach its treas hold will win, and to neuron will respond to that.