Serotonin is a neurotransmitter produced in the brain known to influence the functioning of the cardiovascular, renal, immune, and gastrointestinal systems.

Any disruption in the synthesis, metabolism or uptake of this neurotransmitter has been found to be partly responsible for certain manifestations of schizophrenia, depression, compulsive disorders and learning problems.

Serotonin originates in neurons deep in the midline of the brainstem. Because these neurons profile diffusely throughout the...