In a healthy brain all the regions exist in a state of equilibrium. When one region of the brain is active, the other regions quiet down.
Dante Chialvo, associate research professor of physiology, Feinberg School, used functional magnetic resonance imaging (fMRI) to scan the brains of people with chronic low back pain as well as a control group free of pain. All test subjects tracked a moving bar displayed on a computer screen. Both groups performed the task well, but those subjects that suffered from chronic pain used their brains in a different way than those in the pain-free group.
Unlike the pain-free group that had a state of equilibrium–while one area is active the others quiet down–the chronic brain patients had one particular region of the brain that remain active. The constant firing of neurons in a region that fails to ‘quiet down’ could cause permanent damage because when neurons fire too often they may change their connections with other neurons and/or even die; basically neurons cannot sustain high activity for only so long.
When you are in pain 24/7, the permanent perception of pain in these areas of the brain cause excessive neuron activity. The continuous dysfunction in the equilibrium of the brain can change the wiring forever and even hurt the brain.
Researchers feel that the changes in the wiring, as a result of excessive neuron firing, may make it harder to make decisions and make it difficult to be in a good mood. It could be that pain produces depression and the other reported abnormalities because it disturbs the balance of the brain as a whole. Chialvo feels additional research in this area needs to be done.