Now, once at the axon hillock, if the stimulation is high enough, if it reaches or exceeds the threshold value, then the axon will generate an action potential. Now an action potential is basically a difference in the voltage between the outside and the inside of our cell. And this creates an electric current that is passed down along the axon. So this electric current is the electric signal. So eventually the electric signal reaches the synaptic bouton or our axon terminal. So the electric signal passes along the axon.