Locked-In Syndrome and PVS: Implications for Brain = Behavior
During our first few class sessions, I became very intrigued by the brain = behavior idea and the I-function. I kept searching for what I thought to be an easy way to approach these complicated issues. We discussed extensively the example of Christopher Reeve, as someone with an intact I-function, but who has lost a certain element of connectedness between total I-function control and his actual body. I became very interested in how the I-function and brain = behavior interrelate. I thought that looking into some information about the persistent vegetative state and the locked-in syndrome would yield a satisfying and definitive answer once and for all. Is a brain still a brain without the I-function? I found no definitive answer, but I was able to convince myself of the "less-wrongness" of the brain = behavior idea.
I first looked into the persistent vegetative state. Below I have reproduced a somewhat technical explanation of how PVS patients are believed not to have an I-function:
Three lines of evidence suggest that PVS patients are "noncognitive, nonsentient, and incapable of conscious experience ." First, motor and eye movement, and facial expressions in response to stimuli occur in stereotyped patterns rather than learned reactions. Second, positron emission tomography reveals cerebral glucose metabolism at a level far below those who are aware or in locked in states. PVS levels are comparable to those in deep general anesthesia and as such are totally unaware and insensate. Third, neuropathological examinations of PVS patients show "lesions so severe and diffuse " that it would be almost impossible, giving our current understanding of neural anatomy and function, to have any sort of awareness. (1) [see site for references within]
As the above passage clearly indicates, patients in PVS lack an I-function. They are totally removed from the world of perceptive experience – they are simply not there. A PVS patient goes through normal periods of sleep and wakefulness, can "grind their teeth, swallow, smile, shed tears, grunt, moan, or scream" (2). When I discovered this, I was quite puzzled. I didn’t understand how someone who is ostensibly not in control of such actions, could exhibit behavior that in my everyday life I observe to be a clear indication of emotion and feeling. These are things that seemed to me should to be absent from the lives of people with this syndrome.
What troubled me I later found out, was simply the fact that these things are remarkably similar to things we might normally think are clear evidence of the I-function. So, my problem with the I-function then became the following: if a human being has no I-function then does brain still equal behavior? It seemed very interesting to me that that the things a PVS patient can do don’t require a functioning mind to do them. That is, the brain, even when seriously injured, can control a range...