I just read Douglas Fields fascinating new book “The Other Brain” in which he brings together all of the recent findings which are now causing the overlooked glia in the brain to be studied and appreciated.
In the field of chronic pain, which costs billions of dollars in lost production and drug addiction, it has often been noted that many of these people do not show pain profiles on electrical studies indicating the presence of pain in their nerves. This has been used to ridicule certain types of chronic pain sufferers such as those with fibromyalgia, chronic fatigue syndrome, complex regional pain syndrome (CRPS), and others. The latest research suggests that chronic pain may have its source in the brain’s microglia, which is odd since glia have no involvement in transmitting normal pain. They found that the microglia, which are activated as part of the immune response to injury and repair, secrete cytokines and chemokines causing neurons to become hyper excited. Several drugs including Minocycline, have been successfully injected into animals to block the normal reaction of microglia to injury, resulting in relief of chronic pain. Microglia has also been found to react to the presence of ATP, which is released by injured neurons, causing chronic spinal cord pain.
The study of the glia is also shedding light on possible connections between glia and addiction. Rats in prolonged treatment with morphine showed increased amounts of inflammatory cytokines, produced by glia, in their blood stream. Targeting glia can reduce or eliminate morphine and other drug tolerances from arising.
They also know that almost all brain cancers involve not neurons, but glia cells. Therefore advances in determining what is formerly ignored cells are up to, will have a positive effect on fighting the horrors of brain cancer.
Part of the glia known as astrozytes are known to be two to ten times more plentiful than neurons in the brain. Microglia are responsible for many of the positive immune responses in our brain and function as white blood cells do in other parts of our body. However, we now know that microglia can cause collateral damage and create many neurological disorders when they are clean and attack missions get out of hand.
Researchers and writers are now speculating as to whether this vast part of the brain that has been ignored is the part of the brain that controls dreaming or the unconscious. Even further out speculation tries to link the massive amounts of junk (DNA) in the human genome to glia cells. “Junk” DNA is DNA that has no known function and glia cells were a large part of the brain that was also thought to have little or no function. Perhaps uncovering a relationship between these two now important features of the human body will result in discoveries that will help us understand the consciousness itself.