Changes

Studies that observed motor cortical neurons concluded that the brain is not concerned with information about muscle length changes from individual afferents, but with the population of muscles afferent input signals that arises in groups of muscles. Another area that has been explored is the relation between proprioception and fatigue from exercise. Some of the clumsiness in movements felt after intense exercise could have an origin in proprioception. An important point is age and proprioception. Evidence shows that a decline in proprioception due to age is responsible for an increase in falls in the elderly <ref name=”2”></ref>.

Studies that observed motor cortical neurons concluded that the brain is not concerned with information about muscle length changes from individual afferents, but with the population of muscles afferent input signals that arises in groups of muscles. Another area that has been explored is the relation between proprioception and fatigue from exercise. Some of the clumsiness in movements felt after intense exercise could have an origin in proprioception. An important point is age and proprioception. Evidence shows that a decline in proprioception due to age is responsible for an increase in falls in the elderly <ref name=”2”></ref>.

==Brief historical background==

==History==

There have been speculations about a muscle sense that date back at least to the 17th century. Von Helmholtz proposed the theory of “sensation of innervation”, in which sensations that would apparently arise within the muscles had origin in the brain, in association with motor commands. The discovery of the muscle sense is attributed to Charles Bell, in 1826. He also speculated about whether the signals were of central or peripheral origin. He questioned, “(do) muscles have any other purpose to serve than merely to contract under the impulse of their motor nerves?” He then wrote that “between the brain and the muscles there is a circle of nerve; one nerve (ventral roots) conveys the influence from the brain to the muscle, another (dorsal roots) gives the sense of the condition of the muscle to the brain.” <ref name=”1”></ref> <ref name=”2”></ref> <ref name=”12”> Winter, J. A., Allen, T. J. and Proske, U. (2005). Muscle spindle signals combine with the sense of effort to indicate limb position. Journal of Physiology, 568(3): 1035-1046</ref>

Von Helmholtz proposed the theory of “sensation of innervation”, in which sensations that would apparently arise within the muscles had origin in the brain, in association with motor commands. The discovery of the muscle sense is attributed to Charles Bell, in 1826. He also speculated about whether the signals were of central or peripheral origin. He questioned, “(do) muscles have any other purpose to serve than merely to contract under the impulse of their motor nerves?” He then wrote that “between the brain and the muscles there is a circle of nerve; one nerve (ventral roots) conveys the influence from the brain to the muscle, another (dorsal roots) gives the sense of the condition of the muscle to the brain.” <ref name=”1”></ref> <ref name=”2”></ref> <ref name=”12”> Winter, J. A., Allen, T. J. and Proske, U. (2005). Muscle spindle signals combine with the sense of effort to indicate limb position. Journal of Physiology, 568(3): 1035-1046</ref>

Two schools of thought developed: one that supported that the muscle sense had an entirely central origin, and another that believed that the main responsible was a peripheral signal (2). Henry Bastian, the originator of the term kinaesthesis, was at the time the only who proposed a hybrid theory that encompassed both central and peripheral components. He abandoned this idea in favor of a purely peripheral mechanism <ref name=”1”></ref> <ref name=”2”></ref>.

Two schools of thought developed: one that supported that the muscle sense had an entirely central origin, and another that believed that the main responsible was a peripheral signal (2). Henry Bastian, the originator of the term kinaesthesis, was at the time the only who proposed a hybrid theory that encompassed both central and peripheral components. He abandoned this idea in favor of a purely peripheral mechanism <ref name=”1”></ref> <ref name=”2”></ref>.