The nervous system is the vast network of cells specialized to carry information (in the form of nerve electrical impulses) to and from all parts of the body in order to bring about bodily activity. In vertebrates, the brain and the spinal cord compose a unique continuous organ called the central nervous system (CNS). Its basic units of communication are the nerve cells (neurons), which consist of a bulbous cell body, and an axon that extends from the cell body and carries signals to other cells. To date a lesion of the spinal cord is leading to irreversible damage.