Serotonin is a neurotransmitter, a chemical that moves back and forth in the space (called the synapse) between two nerve cells, or neurons. When one neuron is ready to send a message to another, it sends an electrical signal to its end, which causes a neurotransmitter such as serotonin to communicate that message to another cell. Once that message has been communicated, the neurotransmitter can stay with the new cell, return to the old cell, or hang out in the space between them.

​Certain neurons are programmed to interact with certain neurotransmitters, and neurons that communicate with other cells via serotonin are found throughout your central nervous system – throughout your entire body (Fuller and Wong, 1990). Neurons that use serotonin........

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