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csandrinic's picture

Propioceptors and the I-Function

Thursday’s discussion about proprioceptors was very interesting to me. If I understand correctly, proprioceptors are located in tendons, muscles, joints, and skin. They respond to stimuli generated by muscle movement and muscle tension and send signals to the brain regarding the position and movement of one’s body. However, all of these signals and messages, though they reach the brain, do not reach the I-function, and therefore we are generally not aware of them. Healthy proprioceptors allow for stability and balance. If proprioceptors are damaged, therefore, the nervous system becomes unable to send the proper nerve signal to the brain, and our notion of the position of our limbs would be incomprehensible. Whereas in class, we looked at the extreme case of a man named Ian Waterman who was completely incapable of determining how his body was positioned without looking at his body, there are also less extreme cases of the loss of sensitivity to the proprioceptors, such as aging and muscle or joint injuries. In the case of aging, as the sensitivity of the proprioceptor cells diminishes with age, they provide the brain with less of the sensory information it needs to maintain balance. This apparently, is the reason why one-third of people over the age of 65 fall at least once a year and incur injuries.

What I find so remarkable about the nature of proprioceptors is the capacity to re-train the nerve pathways in our nervous system to recognize the position of the joint in space. This retraining usually comes in the form of specific exercises related to improving and restoring balance. Doing these exercises is much like the way in which Ian Waterman is capable of moving by consciously paying visual attention to his limbs. Studies show that after three months of regularly performing movements aimed at sharpening balance, the vast majority of elderly subjects restored a level of body control and posture stability. What I understand from this is that the only way to stabilize the proprioceptors, which are in charge of unconsciously perceiving movement and spatial orientation, is to make a conscious effort to do so. In other words, the actions go through the I-function box rather than skipping it. Does this cancel out the function of the proprioceptors themselves? This fact makes me wonder whether the body is capable of functioning without them (although they are obviously extremely useful) by creating a back-up system in which conscious visual stimulation enables the body to be aware of its movement and posture. This would reinforce the theory that the brain and body are capable of creating ‘back-up’ systems and essentially rectifying a problem by creating a new solution.

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