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I've been thinking about what was said in class about spastic paralysis and about involuntary movement in general... At the risk of sounding spectacularly obvious, it's a strange concept that we sometimes can't control our own bodies. Tic disorders and the like have always interested me because those suffering don't want to do the things they do. I often wondered why exactly they couldn't consciously override whatever impulse they were feeling... And where in the world did that impulse come from, anyway?

Of course, tic disorders are very different from spastic paralysis. The movements sufferers make are voluntarily made in order to relieve an irrational urge. But... What does that look like? I mean, in what way are involuntary movements and voluntary movements made to relieve an urge different in how they're carried out? How are the brain signals different? I can't imagine the mental anguish associated with disorders such as Tourette's. One would feel hopeless, as if one's mind were against oneself. It sounds scary... Although to some degree we all feel that way at times. I'm sure we've all had problems with self-discipline before and we can't control certain things (such as the moment when we're able to fall asleep).

I was reading something about alien hand syndrome as well... In this disorder, one of the sufferer's limbs acts without conscious intent on the part of the individual. It's thought that this arises from damage in the corpus callosum. A simple way to break it down is to say that the will reported by the left hemisphere does not correspond with the actions performed by the right hemisphere. Another odd thought, isn't it? Does each hemisphere have separate wills? What do we even mean by will anyway? Can there be many wills in an individual? Or can there only be one that results from unblocked communication among all parts of the brain?

Even in neurotypical people the answer is difficult to see. It reminds me of Libet's famous experiment in which he asked his subjects to make a movement randomly and, while watching a clock with a third hand, denote the instant at which they consciously decided to move. In general, he found that people felt the will to move half an instant after brain activity associated with the movement was recorded by his machines. It's not a perfect experiment, but the message hits close to home: do we consciously make decisions? Or do we just think that we do? Maybe our minds know more than we ourselves do... If that makes any sense at all.