LIFE WITHOUT PROPRIOCEPTION

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Proprioception is easy to take for granted because vision usually compensates for its mistakes. But give this a try: Stand on one foot with your eyes open. A little shaky maybe, but possible. Now stand on one foot with your eyes closed. Much harder, isn’t it? When you close your eyes, your brain has to rely on proprioception alone, without benefit of vision.

Without proprioception or the vision to overcome its loss, people fall into a heap. Seriously. Consider Ian, a man infected with a rare virus that attacked only his proprioceptive nerves, destroying their ability to send messages from his body to his brain. All other senses, plus his motor function, were intact. But without proprioception, Ian couldn’t sit up, stand, speak, drink or eat. His body was floppy, like dead weight, and his brain didn’t know the position of his limbs or torso.

Only by virtue of vision and extreme determination did Ian teach himself to sit up and, later, stand. By staring at his feet, he learned to position them for an upright stance. Then, he’d look at his legs and get them in the right spot, and so on for the remainder of his body. Just to stand still, he had to learn consciously the visual position of each joint and muscle. Once all the parts were consciously placed, he could stand while staring at his body. If he looked away, closed his eyes or lost mental concentration, Ian collapsed like a string of

spaghetti.