I am comfortable with the notion that brain=behavior. What I am uncomfortable with, or more specifically curious about, is our "man with the severed spinal cord." My question is, if the link between the brain and the rest of the body is severed, at least at the level of the nervous system, how does that body function at all? I understand that there are structures and regions in the brain that control specific parts of the body; for example, the cerebellum is involved in muscular coordination, the medulla in vital functions, the hypothalamus in basic biological needs...the list is endless. Now, I know that regions like the pituitary gland interact with other organs through the bloodstream. But is that the only way, after severing the spinal cord, that the brain can communicate with the rest of the body? Does the bloodstream need to work overtime? Or do most signals travel that way normally? I guess the brain probably doesn't need to go through the spinal cord to, say, tell the heart to beat or the lungs to draw in air; but it still seems difficult to me that a person could at all function in such a condition. Would he "know" that he was hungry or thirsty? What about temperature regulation? As I am writing this, I am reminded of the "autonomous properties" that we talked about, both in this class and in bio lecture. And although I am comfortable with that aspect of biological organisms, I still cannot help wondering how this situation would really work, or if it would really work at all.

Good questions/concerns. Both generally (how do semi-autonomous entities work in coordinated way?) and specifically. Don't myself know enough about it, but hunger and thirst interesting issues. To the extent that the relevant sensory signals have to enter via the spinal cord, these would be lost. However, some part of "hunger", "thirst" almost certainly has to do with sensory receptors monitoring blood sugar and osmolarity in the medulla, and these should be intact. I suspect one would see some retention and some loss similarly in the other situations you mention. PG