Proprioceptive system: Difference between revisions - VR & AR Wiki

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For much of the 20th century, the prevailing view regarding the limb position sense was that the joints where the main receptors responsible for kinaesthetic sensations. This changed after the experiments of Goodwin and colleagues on the sensory effects of muscle vibration. This study provided evidence for the role of muscle spindles in conscious sensation and currently they are considered the principal proprioceptors <ref name=”2”></ref> <ref name=”9”></ref> <ref name=”12”></ref>.

The term “proprioception” was introduced by Sherrington in 1906. The term is a combination of the Latin “propius” (one’s own) and “perception”. He described it as a type of feedback from the limbs to the central nervous system. He referred to proprioceptors as: “‘In muscular receptivity we see the body itself acting as a stimulus to its own receptors – the proprioceptors.” <ref name=”1”></ref> <ref name=”10”></ref> <ref name=”11”></ref>

The term “proprioception” was introduced by Sherrington in 1906. The term is a combination of the Latin “propius” (one’s own) and “perception”. He described it as a type of feedback from the limbs to the central nervous system. He referred to proprioceptors as: “‘In muscular receptivity we see the body itself acting as a stimulus to its own receptors, the proprioceptors.” <ref name=”1”></ref> <ref name=”10”></ref> <ref name=”11”></ref>

==The proprioceptive senses==

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===Evidence===

There is strong evidence in support of muscle spindles as the main proprioceptors. Their role has been studied through the illusory movement sensation paradigm, and it is based in two kinds of experiment that generate the illusion of limb displacement. First, and maybe the most important evidence, is the fact that using muscle vibration over the tendon or muscle – a selective stimulus for muscle spindles – generates illusions of limb movement and displacement, provided the muscle remains passive. This was first observed by Goodwin et al. (1972). The second piece of evidence comes from the thixotropic property of extrafusal and intrafusal muscle, meaning the dependence of passive tension in muscle on the previous history of contraction and length changes. This second method has the advantage of changing muscle spindle background activity without changing the muscle length <ref name=”2”></ref> <ref name=”5”></ref> <ref name=”7”></ref> <ref name=”10”></ref>.

There is strong evidence in support of muscle spindles as the main proprioceptors. Their role has been studied through the illusory movement sensation paradigm, and it is based in two kinds of experiment that generate the illusion of limb displacement. First, and maybe the most important evidence, is the fact that using muscle vibration over the tendon or muscle , a selective stimulus for muscle spindles, generates illusions of limb movement and displacement, provided the muscle remains passive. This was first observed by Goodwin et al. (1972). The second piece of evidence comes from the thixotropic property of extrafusal and intrafusal muscle, meaning the dependence of passive tension in muscle on the previous history of contraction and length changes. This second method has the advantage of changing muscle spindle background activity without changing the muscle length <ref name=”2”></ref> <ref name=”5”></ref> <ref name=”7”></ref> <ref name=”10”></ref>.

Further evidence has been provided by studies that use other techniques such as skin and joint anesthesia, and the disengagement of muscles from joints. For example, the sense of position and movement persisted after joint replacement. In patients that had a total hip placement, the kinaesthetic sense remained intact, pointing to the importance of muscle receptors in proprioception. It also suggest that, at least at some joints, joint receptors do not play a significant role in kinaesthesia <ref name=”2”></ref> <ref name=”7”></ref>.

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The effect of exercise in the sense of position remains controversial to explain, and further research is necessary. Some studies suggest a decline of the sense of velocity and position sense after an isometric contraction exercise protocol. Indeed, there is a common feeling of awkwardness and clumsiness after intense exercise that is not only muscle weakness, but also a lesser certainty about the placement of the fatigued limbs in the absence of vision <ref name=”2”></ref> <ref name=”5”></ref>.

There is also the suggestion that the effort that is required to maintain the position of a limb against the force of gravity is the element that provides the positional cue, although some studies contradict this sense of effort hypothesis. Moreover, data supports the view that muscle spindle would be responsible for the sense of movement, not being sensitive to exercise disruption <ref name=”5”></ref>.

==Proprioception and virtual reality==

Proprioception allows the formation of a mental model, describing the spatial and relational dispositional of the body and its parts. A virtual reality system needs that the normal proprioceptive data that is used to form a mental model of the body be overlaid with sensory data that is supplied by the computer-generated displays. For an effective virtual reality, it is fundamental that there is consistency between proprioceptive information and sensory feedback. This is done by the correct capturing of the movement of the user, and simulating it in the virtual environment, in order to increase a sense of immersion <ref> Slater, M., Usoh, M. and Steed, A. (1995). Taking steps: the influence of a walking technique on presence in virtual reality. ACM Transactions on Computer_Human Interaction, 2(3): 201-219</ref>. Also, according to Mine (1997), “providing a real-world frame of reference in which to operate and a more direct and precise sense of control, proprioception helps to compensate for the lack of haptic feedback in virtual-environment interaction.” <ref> Mine, M. R. (1997). Exploiting proprioception in virtual-environment interaction. PhD thesis, University of North Carolina</ref>

==References==