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Proprioception. For those of you who are not familiar with what this means, it is one of the senses in the body (true story - there are really more than five!) Proprioception is your brain's sense of where your body is in space, and without it, simple tasks (like standing or sitting even) are difficult or even impossible. When I learned about proprioception, I truly never realized quite how important it was, or what a life would be like without it....this is until I heard the story of a man who had lost this sense forever.
A couple years ago while in studying on the rock, I got into the habit of watching documentaries about medical topics, and I found this one most fascinating - The Man Who Lost His Body. Now that I am in residency, I find myself with my TV-watching hours not coordinating with normal prime-time TV, so I've gone back to the docs, and I re-watched this one again. It is a BBC documentary about this guy who was working in a butcher shop at the age of 19, when he came down with some viral illness. During this illness, he slowly lost the ability to feel anything below the neck, and along with this, he lost his sense of proprioception. The man could not feel where his limbs were in space, and he lost all control of his body. He is one of only a few people in the world who have suffered from this 'disease,' and he is (or at least was when the documentary was made) the only one who is able to walk.
The
human brain is a truly amazing organ; my favorite part of the body to
learn about, and the part of the body we will know the least about. One
interesting feature of the brain is that it is plastic
(not in the rubber, made of plastic sense, but in a whole other way).
When I say that the brain is plastic, I mean that it has the ability to
change and adapt to our environments, our behaviors, and our conditions -
this is called Neuroplasticity. It's how the body responds to injury; when something happens to one neural pathway, your brain will find another one.
"If you are driving from here to Milwaukee and the main bridge goes
out, first you are paralyzed. Then you take old secondary roads through
the farmland. Then you use these roads more; you find shorter paths to
use to get where you want to go, and you start to get there faster.
These "secondary" neural pathways are "unmasked" or exposed and
strengthened as they are used. The "unmasking" process is generally
thought to be one of the principal ways in which the plastic brain
reorganizes itself."
-Bach-y-Rita, one of the people who first studied plasticity
In
the case of the man in the story, as he built these new pathways in
order to walk, by consciously telling his muscles what to do, his brain
eventually adapted to his inability to feel and control his body. All these movements that were originally unconscious, which then had to be conscious, again became (in part) unconscious;
as he had to create/find new pathways for making himself move, they got
stronger and faster until they were nearly as strong as the original
pathways. He was able to walk (as long as he could watch his legs doing
their thing)....and this is really the key - if he can see his body move
he has control, but if he can't he does not. This opens up the ability
for a very cruel joke if this guy's in a room with no windows - turn of
the lights and he'll slump to a pile on the ground!
As we have all heard "you can't teach an old dog new tricks,"
and this does seem to be one of the limitations to neuroplasticity -
it's more effective in younger people, and older brains have had more
difficulty adapting to injury and change than younger ones (have you
ever tried to watch your grandma/grandpa/any 80-year-old try to send an
email? It's like a whole ridiculous process for them! Yet my 6 year old
nephew seems to have the concept down pat.) In short, one of the reasons
the man in the documentary was likely able to get himself walking
again, was because he had to relearn how to use his body at 19, when his
brain was still very plastic and pliable. Most (or even all) others
afflicted with this weird condition have not been so lucky, so (as you
can see in the opening scene of the documentary), they can barely
crawl.....sad :-(
We take for granted the fact that our brain allows us to move, walk, grab, and make all other movements without having to think about all that is involved in these actions. We do not have to tell certain leg muscles to contract while others relax in order to take a step. We do not have to control the hundreds of muscle fibers in our hand when grabbing our cups of coffee. Our body just does these things when we tell our brain it's what we want to do. Well, this is something that you lose when you lose your proprioception. If you think of an example - imagine you have no feeling in your body, so hypothetically, you would not be able to feel the bottoms of your feet standing on the ground; if you can't feel your feet on the ground, then your brain wouldn't know they were there and so it could not tell all the big (and little) stabilizing muscles in your legs, hips, buttocks, back, and abdomen what to do in order to keep you upright. In short, you would just fall into a pile on the floor. The man in the story would tell his brain he wanted to lift his arm, but he could not. He just lay there....for weeks. And after laying there for weeks, he eventually got tired of his inability to do anything (and his desire to just die), and he taught himself to control his body.
Slowly, muscle by muscle, he was able to start moving. It was difficult at first - he would have to tell one muscle to contract while making sure another one would stay relaxed, and he had to do this all consciously. Over time, he was able to lift his arms, and move his body, but the key was that he had to be able to see these parts of his body to do so (remember, no feeling in your body means not being able to feel where they are, and if you can't feel where they are, you can't know what to tell them to do.) At the time that this documentary was made (1997) there were less than 10 similar reported cases, and this man was the only one who could walk....through hours, days, weeks and months, he trained his brain over and over and over again, what he had to do in able to take those steps. Now keep in mind that there is more involved that just telling his muscles that they have to contract or relax - he needed to be able to tell them how much to contract or relax. He had to be able to look at things he was picking up (for example), and guess how much force it would take to do so, otherwise he either wouldn't be able to pick it up, or he'd be flinging it across the room! The perseverance and determination that this must have taken, in order to get to a (semi) normal way of functioning is truly mind-boggling to me.
Anyways, here are the links to the video
via you tube (better quality, but in 5 parts):
via random website (fuzzy quality, in 1 part):
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