http://goo.gl/VfGmmb
A prime example is oxytocin, which is involved in fostering emotions such as trust and love. The hormone is produced only in the brain and is released into the bloodstream by the pituitary gland. Until now it was not known why these oxytocin-producing neurons are linked to the brainstem and spinal cord. Researchers at the Max Planck Institute for Medical Research in Heidelberg have now discovered a small population of neurons that coordinate the release of oxytocin into the blood and also stimulate cells in the spinal cord. Stimulation of these cells increases oxytocin levels in the body and also has a pain-relieving effect.