13 Sep Pogo Pulse Propioception, more than just jumping up and down
the-scientist.com – 1st September, 2016
In 1971, at the age of 19, Ian Waterman suffered a bout of severe viral gastroenteritis. The illness triggered an autoimmune response that stole his ability to gauge where his limbs were in relation to their environment. As described by Columbia University neurologist Jonathan Cole, Waterman was not paralyzed; his limbs moved, but he had no control over them. He felt disembodied, as if he was floating in air.
The five basic senses—sight, hearing, smell, taste, and touch—enable us to perceive the world around us. But what about sensations generated by the actions of our own bodies? As Waterman’s case demonstrates, the ability to sense our bodies is critical for telling us where we are in our surroundings as well as for the execution of normal movements. Sometimes referred to as the “sixth sense,” proprioception includes the sense of position and movement of our limbs, the senses of muscle force and effort, and the sense of balance. These senses, triggered by our everyday activities, allow us to carry out our tasks successfully, without thinking; absent feedback from proprioceptors, we, like Waterman, would be lost.
We remain largely unaware of the actions of the sense organs responsible for generating our proprioceptive senses. Have you ever stood in a darkened room and tried to touch the tip of your nose with your index finger? Most of us can do that with uncanny accuracy without even trying. But if we cannot see it, how do we know where our arm is as it travels through the air aiming for the nose? And how do we know where our nose is? To make things even more bizarre, if the biceps muscle of the arm touching the nose is vibrated, it generates the sensation that the arm is lengthening and the nose is beginning to grow. All of this is the subject of proprioception.
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