So that is shown in the following diagram, the sodium channels open up and our sodium ions move into the cell, as shown. And that will cause the inside of the cell membrane to become positively charged and the outside to become negatively charged. Now, notice, the adjacent region of the cell membrane still contains a negative charge on the inside and the positive charge on the outside. The question is, how exactly will the adjacent section of the cell membrane be influenced by the influx of the sodium ions into the cell? So it turns out that the increase of the positive charge inside the cell where the stimulus actually took place will cause an increase in the positive charge found in the region right next to where the stimulus actually took place. So what that means is, as we have a build up of sodium ions in this region, that will influence the charge value on the region right next to it.