The respiratory center is located in your medulla oblongata, and area of your brain stem. This area is also highly saturated with neuropeptides, or “molecules of emotion.” These molecules are dumped into the nearby fourth ventricle and carried down the body’s spinal cord via CSF (cerebrospinal fluid)
Interestingly, those who are depressed often do not breathe as well. Improving breathing may actually improve endogenous depression (depression caused from chemical imbalance). Abdominal breathing is not only great training for our core (as the diaphragm roofs this entity) but allows for longer, more quality breaths (as opposed to shallow, rapid breathing, as is often seen from breathing with accessory muscles).