The behavior of a person with a broken neck helps show that the communication between the spinal cord and brain are important, as are the individual components. But it also brings up questions about the exact function of the spinal cord and nerves. A person with a severed spinal cord can still communicate with others because the 12 cranial nerves leave the brain above the spine and are not effected by the break we are discussing. Additionally, the vagus nerve controls the heart and viserea, so their basic life functions continue. Also, their mucscles and limbs respond to touch and will withdraw from a painful touch. The person cannot feel the touch, nor can they control their limbs. So both their spinal cord and brain are intact, but they simply are not connected. In a person with a broken back, they will have all movement above the break in the spinal cord, but none below. Again, the lower extermities will move when touched, but the person will not be aware of the touch. So the situation is the same as the person with the broken neck. But movement and sensation are also effected by other things. In people with a stroke, there is loss of movement and sometimes of sensation. This is often because a whole side of the brain will be effected and this side has sensation input areas and muscle control areas. Their spinal cord is fine and the communication to the brain is fine, but their brain is damaged. Additionally a person with nerve damage may not be able to feel their limbs, or move properly. But their brain and and brain/spinal cord connection are intact. This shows that all three are important to the normal functioning of a person.

However, many people with strokes recover a lot of the function and feeling that they have lost. Other areas of the brain take over the responsibiliteis of the damaged area. Additionally, if the hypothalamus is suddenly disturbed, a person will die, but if there is a slow growing tumor in the area, the person will not be effected. The responsibilities of the hypothalamous transfer to other parts of the brain. So why does this not happen in the spinal cord ? The nerves in the damaged area of the brain do not grow back, nor do they heal. Their functions are just taken over. Since the rerouting is possible in the brain, but not in the spine, does this mean that something other than the spine is responsible for movement? Does this suggest that the neurons in the body are highly specific and non-adaptive, whereas the neurons in the brain can change their patterns of use much more readily? The vagus nerve is still intact, so why cannot the signals be rerouted to this nerve, which would then connect the body to the brain. Or perhaps the body is structured so that this would not be possible, and there is no bypassing of the spine. But then how do you explain quardraplegics who learn to walk, or regain thir feeling? Do they just have damaged spines, and then part of the spinal cord takes on the responsibility of the rest of it. What if the vertral side is damaged. Does that mean there is no output, or would the dorsal root shift to take on both responsibilities? The case of a person with a broken neck brings up many more questions of why there body cannot adapt, as well as how it changes their behavior.

Interesting take on the whole thing. There is a very substantial amount of anatomical specifity in the nervous system, which sharply constrains information flow paths (as we'll talk more about). At the same time, it is indeed true that abnormalities associated with damage to some areas lessen with time. This may be because of new connections, or old connections taking on new functions, as you suggest. But it may equally be because the damage to one area temporarily disturbs the function of other areas, with the recovery not involving any new or substantially reorganized connections at all. We'll try and talk more about this too. PG