The central nervous system (CNS) is comprised of the brain and spinal cord. The CNS controls all functions of the body and mind. The brain is the center of our thoughts, the interpreter of our external environment, and the origin of control over body movement. Like a central computer, it interprets information from our eyes (sight), ears (sound), nose (smell), tongue (taste) and skin (touch), as well as from internal organs such as the stomach. It controls all voluntary movement, such as speech and walking, and involuntary movement like blinking and breathing. It is the core of our thoughts, perceptions and emotions.
The spinal cord is the highway for communication between the body and the brain. When the spinal cord is injured, the exchange of information between the brain and other parts of the body is disrupted. Many organs and tissues in the body can recover after injury without intervention. Unfortunately, some cells of the central nervous system are so specialized that they cannot divide and create new cells. As a result, recovery from a brain or spinal cord injury is extremely difficult.
The complexity of the central nervous system makes the formation of the right connections between brain and spinal cord cells very difficult. It is a huge challenge for scientists to recreate the central nervous system as it existed before the injury. Cells called neurons connect with one another to send and receive messages into the brain and spinal cord. Many neurons working together are responsible for every decision made, every emotion or sensation felt, and every action taken. As many as 10,000 different subtypes of neurons have been identified, each specialized to send and receive certain types of information.
Each neuron is made up of a cell body, which houses the nucleus. Axons and dendrites form extensions from the cell body.
"Source: The Reeve Foundation"