Sigmund Freud felt a need to clarify the concept of the subconscious mind, and invented a new terminology to differentiate between the counscious and non-conscious. For him, the conscious was limited to the things that are going on in our immediate mental environments, i.e., what we are thinking at any given moment. Anything else was non-conscious, although the 'upper' half of the non-conscious mind was designated the pre-conscious, things that could very easily be in our conscious should we choose to think about them...things that can often be recalled by questions, "What color is my radio?" "When did I get that phone call?" These are often things we tune out of our conscious minds, but are always available for consideration, sometimes with more difficulty than at others. The 'unconscious' for Freud encompassed what we typically refer to as the subconscious, hidden, repressed, traumatic, blocked, undercurrents, events and experiences that we can not think about or even know existed at all, but that are sometimes revealed through dreams, slips of the tongue, and extensive psychoanalysis. Autonomous nervous system activity was generally considered to be a part of the subconscious, and Freud extended his 'unconscious' to cover those functions, although in reality many of them could be better considered to be preconscious, in that when we think about our breathing and heartbeat, for example, we can become aware of their activity, and sometimes consciously alter it. Certain n.s. activities are beyond the control or comprehension of the conscious mind however, such as hormonal release by the hypothalamus, blood pressure, certain other homeostatic mechanisms, etc. The concept of the human with the broken neck presents a problem different from all of these levels of consciousness. Something that is sensed by the nociceptors, passed to the dorsal root ganglia, to the spinal cord, through the ventral root, back to the motor neuron of the neuromuscular junctions in the leg, is definite behavior, and since the connections to the most rostral end of the spinal cord (the brain) where "consciousness" as Freud defines it is localized for the most part, are non-functioning, this stimulus-response cannot really be said to fall under any of the categories of consciousness supra. Consciousness as we know it is so far removed from this activity that it may as well occur in another organism.

The implications that this has on the importance of communication between neurons and other neurons, and especially neurons and the I-function, are that if 'we' don't 'know' what is happening at least on some level of brain-consciousness, it may as well not be happening. When that person's neck is broken, the brain ceases to be part of a larger body and it's related nervous system, and becomes a head with a life-sustaining apparatus attached at the neck. The body that we would normally consider to be part of a human being, and have a mind and a soul, may as well be a nutrient bath/respirator/circulation system like something out of a bad sci-fi movie, with a disembodied head attached. Which begs the question...when are necks are whole, does are body really have a mind? Or just a head, which in turn has mind.

I think, as long as we have skin to sense, and/or fingers with which to manipulate our world, or feet to propel us around within the world, our body is part of our higher consciousness. Otherwise it may as well be a lump of dirt, as long as our head were kept alive.

We could proceed to remove parts of the head from consciousness, too. Taste and all of the skin sensations of the face and head could be cut with a couple of cranial nerves, and our minds would still be essentially human. As long as there is some, however limited capacity for input and output of language and other stimuli/response, the consciousness remains unaffected and recognizable. About what goes on with complete sensory deprivation, we have an idea, from astronaut training, etc, but once means of communication are cut, we have no way of knowing if consciousness still exists. If the brain were kept alive, but removed from all input/output, how long could it survive on just the energy inside it (imagine the brain feeding off of action potentials that propogate each other continuously). Would someone put in this kind of state go instantly insane? Would we even be able to recognize their insanity? Imagine that the brain, after a long period of deprivation, is put back into a body.

Perhaps a tangental idea gotten out of hand, but it's interesting, and a little haunting, especially to consider oneself in the situation.

Neither so tangential, nor so out of hand. Thanks for bringing Freud along, he certainly belongs in the conversation. I'm not entirely sure I understand Freud's different levels of conscious/unconscious, or yours, but I wouldn't dismiss out of hand efforts to draw connections between them and the paraplegic. In intact nervous systems, there are, I suspect, close parallels to the lack of communication between parts of the nervous system which can result from trauma, as well as to the kind of indirect transmission of information which corresponds to slips of the tongue and the like. As for the isolated brain/head, that too is not so farfetched. A classic literature on sensory deprivation makes it pretty clear that consciousness indeed persists in the absence of sensory input ... and there is good supporting evidence from being able to look inside the brain, which will get to later in the course. PG