Abstract
The periaqueductal gray (PAG) is a mesencephalic region that surrounds the cerebral aqueduct. The PAG was divided functionally into four longitudinal columns arranged along the rostrocaudal axis: dorsomedial, dorsolateral, lateral and ventrolateral. Microinjection of excitatory amino acids into the ventrolateral PAG (vlPAG) caused decreases in blood pressure, heart rate, sympathetic acti…