Periaqueductal gray (PAG)

Located in the brainstem, the PAG plays a critical role in autonomic function, motivating behavior and behavioral responses to threatening stimuli. Previous studies have implicated this brainstem region in numerous functions, including fear conditioning, pain modulation, altruistic behaviors, and unconditional love. The PAG is also the primary control center for pain modulation, sending information to the brain’s cerebral cortex about pain. The PAG contains a high density of oxytocin that plays a role in social bonding, and vasopressin that also plays a role in social behaviors—and may be specifically involved in human maternal behavior. Its activity likely reflects one aspect of the pleasant emotions associated with motherly love. The PAG is activated by pleasant, visual, tactile, and olfactory stimuli—depending on pleasantness rather than on intensity of stimulation. Now it appears that the periaqueductal gray plays a role in spirituality.