The chemistry of the Synapse creates a vital switch which provides inhibition or control of neural pathways.
The change of valence at the point of entry of the ions creates an electrical gradient (potential) that moves through the cell like a wave. When it reaches the end, the process is repeated for the next connecting neuron. Several things must be noted about this process.
The specific neural transmitter emitted by a cell determines whether or not ions will enter the next connecting cell.
This makes the synapse, in essence, a switch which can turn on or off a particular neural pathway. This mechanism is critical to the function of the brain. It provides for inhibition, or the ability to turn off a pathway.
When these switches fail, electrical storms are free to wander unchecked through the brain wreaking havoc with normal neurological processes. These are called seizures.