The<unk>  <unk> , also known as the central<unk>  is a brain region that plays a critical role in autonomic function, motivated behavior and behavioural responses to threatening stimuli.<unk>  is also the primary control center for descending pain modulation. It has enkephalin-producing cells that suppress pain. The<unk>  is the<unk>  matter located around the cerebral aqueduct within the tegmentum of the midbrain. It projects to the nucleus raphe magnus, and also contains descending autonomic tracts. The ascending pain and temperature fibers of the spinothalamic tract send information to the<unk>  via the spinomesencephalic tract (so-named because the fibers originate in the spine and terminate in the<unk> , in the mesencephalon or midbrain). This region has been used as the target for brain-stimulating implants in patients with chronic pain.
Periaqueductal gray
Barrel cortex
Fusiform body area
Watershed area 
Piriform cortex
Midbrain tegmentum
Fields of Forel
Postcentral sulcus