This is my third drawing for neuroscience class and it is showing the voltage changes and what is going on during the time when a neuron fires. The resting potential is about -70 millivolts, it shoots up to about +30 millivolts and then comes back down below the resting potential before it returns to the resting potential of -70 mV. This all happens in about 1-5 milliseconds depending on the particular neuron. FAST! :) Oh, also keep in mind that we have about 100-500 BILLION neurons in our heads too and nine times as many glial cells!!!