Serotonin..

Serotonin is a hormone in the brain that transmits signals between nerve cells.  It causes blood vessels to narrow.  It is mostly concentrated in the midbrain and the hypothalmus.  But it is also found in the intestinal tract, blood and the immune system.  It travels between nerve cells.  It is believed that when there is clinical depression, serotonin is reabsorbed back into the nerve cells.  SSRI's block the reuptake. 
Migraines can be caused by extreme fluctuations in the serotonin levels.  The serotonin constricts the blood vessels and then releases.  This is what causes the spasm in the arteries at the base of the brain.

LENS neurofeedback helps the brain to heal.  It lets the brain release the places that are blocked.  SSRI's can be reduced or eliminated.