When the spinal cord has been disconnected from the brain, we observe that the brain and the spinal cord continue to function independently of each other: the foot withdraws when pinched, and the head hears and speaks. If the brain attempts to initiate movement in the foot, however, there is no resulting movement. This is because the physical contiguity between these two parts of the NS has been interrupted; information cannot be transferred from the brain to the spinal cord (and, thus, to the foot). Observations of the same individual also reveal that the/an "I-function" exists in the brain, since it retains the ability to acknowledge and convey self-existence in a way that existence is recongnized by others--that is, the rostral region of the NS is able to talk.

We don't know, though, that there is no "I-function" in the spinal cord just because it won't respond to a question such as, "Are you there?" What is it that the "I-function" consists of? Is it solely the ability to be "aware"? Or does it require the ability to initiate behavior (create output w/out input)? Does the spinal cord ever initiate movement or other behavior?

What if there was a separation in the connection between, say, the midbrain and the thalamus (instead of between the spinal cord and medulla)? Would the individual lose more than his eye-sight and sense of smell? What about if the NS were cut in both of the aforementioned locations? I would predict (based on the behavior of the individual w/ a broken neck) that each part of the NS would be able to carry out its functions as long as it was still connected to whatever it was designed to control. ... But for some reason, it's hard for me to imagine one part of the brain doing anything without the rest of it...

P.S. I've heard that humans only use a fraction of their brain (something like less than 10%). What exactly does this mean?

Yeah, is hard to imagine, but is so. In the case described, and in others as well (as we'll see). Its important, and I think you'll get used to it after a while.

PS I've heard that too, don't know what it means, and suspect its more or less like one's mother or father telling one to pay more attention to what one is doing (which may, but doesn't necessarily, mean using more of one's brain (anatomically defined). PG