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| | Periaqueductal gray - Wikipedia, the free encyclopedia |
 | | The spinomesencephalic tract is so-named because the fibers orginate in the spine and terminate in the mesencephalon, another name for the midbrain, which is the part of the brain in which the PAG resides. |
 | | Stimulation of the periaqueductal gray matter of the midbrain results in release of serotonin in the dorsal horn of the spinal cord, profound analgesia, activation of interneurons containing enkephalin, and release of norepinephrine (also known as noradrenaline) in the dorsal horn of the spinal cord. |
 | | Stimulation of the dorsal and lateral aspects of the PAG [in the rat] can provoke defensive responses characterised by freezing, running, jumping, tachycardia and increases in blood pressure and muscle tonus. |
| en.wikipedia.org /wiki/Periaqueductal_gray (349 words) |
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