In the brain, nerve cells run through other brain cells called astrocytes. When nerve cells in the pain circuit fire continuously, these astrocytes release inflammatory molecules that keep the nerve cells firing. This leads to the pain processing nerve cells taking on nerve cells from less active surrounding areas and expansion of the pain map in the brain. This also results in more of the main pain neurotransmitter being produced and sent back to the area in the body where the injury or dysfunction has occurred, resulting in a chronic inflammatory response
