[subcosmos]

There is something special about serotonin - throughout evolution, it has been an important part of regulating social emotional processing in animals and humans. It strongly regulates the function of the salience network in the brain, alterations of which are associated with anxiety disorders.

Like other neurotransmitters, serotonin is specifically synthesized in a specific brain region, the raphe nuclei. (Dopamine is from the substantia nigra)

Brain circuits have lots of overlap but they definitely have specialization. Case in point, genes associated with serotonin processing have SNPs for depression-like illnesses.

Sapolsky gives one of the better lectures on the specific features associated with abnormal serotonin, dopamine, or neuropinephrine signaling, and their associated symptomology. Ultimately it's the job of the psychiatrist to figure out what's out of balance based on behavior.

https://www.youtube.com/watch?v=NOAgplgTxfc