proprioception
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The cerebellum is largely responsible for coordinating the unconscious aspects of proprioception.
Proprioception ({{pronEng|ˌproʊpriːəˈsɛpʃən}}
PRO-pree-o-SEP-shun); from
Latin proprius, meaning "one's own" and perception) is the
sense of the relative position of neighbouring parts of the body. Unlike the six
exteroceptive senses (
sight,
taste,
smell,
touch,
hearing, and
balance) by which we perceive the outside world, and
interoceptive senses, by which we perceive the pain and the stretching of internal organs, proprioception is a third distinct sensory modality that provides feedback solely on the status of the body internally. It is the sense that indicates whether the body is moving with required effort, as well as where the various parts of the body are located in relation to each other.
History of study
{{Unreferencedsection|date=January 2008}}The position-movement sensation was originally described in 1557 by
Julius Caesar Scaliger as a 'sense of locomotion'. Much later, in 1826,
Charles Bell expounded the idea of a 'muscle sense' and this is credited with being one of the first physiologic feedback mechanisms. Bell's idea was that commands were being carried from the brain to the muscles, and that reports on the muscle's condition would be sent in the reverse direction. Later, in 1880,
Henry Charlton Bastian suggested 'kinaesthesia' instead of 'muscle sense' on the basis that some of the afferent information (back to the brain) was coming from other structures including tendons, joints, and skin. In 1889,
Alfred Goldscheider suggested a classification of kinaesthesia into 3 types: muscle, tendon, and articular sensitivity. In 1906,
Charles Scott Sherrington published a landmark work that introduced the terms 'proprioception', 'interoception', and 'exteroception'. The 'exteroceptors' are the organs responsible for information from outside the body such as the eyes, ears, mouth, and skin. The interoceptors then give information about the internal organs, while 'proprioception' is awareness of movement derived from muscular, tendon, and articular sources. Such a system of classification has kept physiologists and anatomists searching for specialised nerve endings that transmit data on joint capsule and muscle tension (such as muscle spindles and Pacini corpuscles).
Proprioception vs. kinesthesia
Kinesthesia is another term that is often used interchangeably with proprioception, though use of the term "kinesthesia" can place a greater emphasis on motion.
(1)(2)Some differentiate the kinesthetic sense from proprioception by excluding the sense of equilibrium or balance from kinesthesia. An
inner ear infection, for example, might degrade the sense of balance. This would degrade the proprioceptive sense, but not the kinesthetic sense. The affected individual would be able to walk, but only by using the sense of sight to maintain balance; the person would be unable to walk with eyes closed.Proprioception and kinaesthesia are seen as interrelated and there is considerable disagreement regarding the definition of these terms. Some of this difficulty stems from Sherrington's original description of joint position sense (or the ability to determine where a particular body part exactly is in space) and kinaesthesia (or the sensation that the body part has moved) under a more general heading of proprioception. Clinical aspects of proprioception are measured in tests that measure a subject's ability to detect an externally imposed passive movement, or the ability to reposition a joint to a predetermined position. Often it is assumed that the ability of one of these aspects will be related to another; however, experimental evidence suggests there is no strong relation between these two aspects. This suggests that, while these components may well be related in a cognitive manner, they seem to be separate physiologically.Much of the foregoing work is dependent on the notion that proprioception is,in essence, a feedback mechanism; that is, the body moves (or is moved) and then the information about this is returned to the brain, whereby subsequent adjustments could be made. More recent work into the mechanism of ankle sprains suggests that the role of reflexes may be more limited due to their long latencies (even at the spinal cord level), as ankle sprain events occur in perhaps 100 msec or less. In accordance, a model has been proposed to include a 'feedforward' component of proprioception, whereby the subject will also have central information about the body's position prior to attaining it. Kinesthesia is a key component in
muscle memory and
hand-eye coordination, and training can improve this sense (see
blind contour drawing). The ability to swing a golf club or to catch a ball requires a finely-tuned sense of the position of the joints. This sense needs to become automatic through training to enable a person to concentrate on other aspects of performance, such as maintaining motivation or seeing where other people are.
Basis of proprioceptive sense
The initiation of proprioception is the activation of a proprioreceptor in the periphery
(3). The proprioceptive sense is believed to be composed of information from
sensory neurons located in the
inner ear (motion and orientation) and in the
stretch receptors located in the
muscles and the joint-supporting ligaments (stance). There are specific nerve receptors for this form of perception termed "proprioreceptors," just as there are specific receptors for pressure, light, temperature, sound, and other sensory experiences. Proprioreceptors are sometimes known as
adequate stimuli receptors.Although it was known that finger kinesthesia relies on skin sensation, recent research has found that kinesthesia-based
haptic perception relies strongly on the forces experienced during touch.
(4) This research allows the creation of "virtual", illusory haptic shapes with different perceived qualities.
(5)Conscious and unconscious proprioception
In humans, a distinction is made between
conscious proprioception and
unconscious proprioception:
Applications
Law enforcement
Proprioception is tested by American police officers using the
field sobriety test, wherein the subject is required to touch his or her nose with eyes closed. People with normal proprioception may make an error of no more than 20
millimeters. People suffering from impaired proprioception (a symptom of moderate to severe
alcohol intoxication) fail this test due to difficulty locating their limbs in space relative to their noses.
Diagnosis
There is a number of relatively specific tests of the subject's ability to propriorecept. These tests are used in the diagnosis of
neurological disorders. They include the visual and tactile
placing reflexes.
(8)Learning new skills
Proprioception is what allows someone to learn to walk in complete darkness without losing balance. During the learning of any new skill, sport, or art, it is usually necessary to become familiar with some proprioceptive tasks specific to that activity. Without the appropriate integration of proprioceptive input, an artist would not be able to brush
paint onto a canvas without looking at the hand as it moved the brush over the canvas; it would be impossible to drive an
automobile because a motorist would not be able to steer or use the foot pedals while looking at the road ahead; a person could not
touch type or perform ballet; and people would not even be able to walk without watching where they put their feet.
Oliver Sacks once reported the case of a young woman who lost her proprioception due to a viral infection of her
spinal cord.
(9) At first she was not able to move properly at all or even control her tone of voice (as voice modulation is primarily proprioceptive). Later she relearned by using her sight (watching her feet) and
inner ear only for movement while using hearing to judge voice modulation. She eventually acquired a stiff and slow movement and nearly normal speech, which is believed to be the best possible in the absence of this sense. She could not judge effort involved in picking up objects and would grip them painfully to be sure she did not drop them.
Training
The proprioceptive sense can be sharpened through study of many disciplines. The
Alexander Technique uses the study of movement to enhance kinesthetic judgment of effort and location.
Juggling trains reaction time, spatial location, and efficient movement. Standing on a
wobble board or
balance board is often used to retrain or increase proprioception abilities, particularly as physical therapy for ankle or knee injuries. Standing on one leg (stork standing) and various other body-position challenges are also used in such disciplines as
Yoga or
Wing Chun. In addition, the slow, focused movements of
Tai Chi practice provide an environment, whereby the proprioceptive information being fed back to the brain stimulates an intense, dynamic "listening environment" to further enhance mind/body integration.{{Fact|date=October 2008}} Several studies have shown that the efficacy of these types of training is challenged by closing the eyes,{{Fact|date=November 2008}} because the eyes give invaluable feedback to establishing the moment-to-moment information of balance. There are even specific devices designed for proprioception training, such as the Proprioceptor system, which consists of shoes with specially designed balls on the soles to make athletes work harder to balance.
(10) Impairment
It has been seen that temporary loss or impairment of proprioception may happen periodically during growth, mostly during adolescence. Growth that might also influence this would be large increases or drops in bodyweight/size due to fluctuations of fat (
liposuction,
rapid fat loss,
rapid fat gain) and muscle content (
bodybuilding,
anabolic steroids,
catabolisis/
starvation). It can also occur to those that gain new levels of
flexibility,
stretching, and
contortion. A limb's being in a new range of motion never experienced (or at least, not for a long time since youth perhaps) can disrupt one's sense of location of that limb. Possible experiences include suddenly feeling that feet or legs are missing from one's mental self-image; needing to look down at one's limbs to be sure they are still there; and falling down while walking, especially when attention is focused upon something other than the act of walking.Proprioception is occasionally impaired spontaneously, especially when one is tired. One's body may appear too large or too small, or parts of the body may appear distorted in size. Similar effects can sometimes occur during
epilepsy or
migraine auras. These effects are presumed to arise from abnormal stimulation of the part of the
parietal cortex of the
brain involved with integrating information from different parts of the body.
(11)Proprioceptive illusions can also be induced, such as the
Pinocchio illusion.The proprioceptive sense is often unnoticed because humans will adapt to a continuously-present stimulus; this is called
habituation,
desensitization, or
adaptation. The effect is that proprioceptive sensory impressions disappear, just as a scent can disappear over time. One practical advantage of this is that unnoticed actions or sensation continue in the background while an individual's attention can move to another concern. The Alexander Technique addresses these issues.People that have a limb
amputated may still have a confused sense of that limb existence on their body, known as
phantom limb syndrome. Phantom sensations can occur as passive proprioceptive sensations of the limb's presence, or more active sensations such as perceived movement, pressure, pain, itching, or temperature. The etiology of the phantom limb phenomenon was disputed in 2006, but some consensus existed in favour of
neurological (e.g., neural signal bleed across a preexisting
sensory map, as posited by
V.S. Ramachandran) over
psychological explanations. Phantom sensations and phantom pain may also occur after the removal of body parts other than the limbs, such as after amputation of the breast, extraction of a tooth (phantom tooth pain), or removal of an eye (
phantom eye syndrome).Temporary impairment of proprioception has also been known to occur from an overdose of
vitamin B6 (pyridoxine and pyridoxamine). Most of the impaired function returns to normal shortly after the intake of vitamins returns to normal. Impairment can also be caused by
cytotoxic factors such as
chemotherapy.It has been proposed that even common
tinnitus and the attendant hearing frequency-gaps masked by the perceived sounds may cause erroneous proprioceptive information to the balance and comprehension centers of the brain, precipitating mild confusion. Proprioception is permanently impaired in patients that suffer from joint hypermobility or
Ehlers-Danlos Syndrome (a genetic condition that results in weak connective tissue throughout the body). It can also be permanently impaired from viral infections as reported by Sacks. The catastrophic effect of major proprioceptive loss is reviewed by Robles-De-La-Torre (2006).
(12)See also
References
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[{{EMedicineDictionary|kinesthesia}}]
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[{{EMedicineDictionary|proprioception}}]
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[JOURNAL, Sherrington CS, On the proprioceptive system, especially in its reflex aspect, Brain, 29, 467–85, 1907,weblink ]
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[JOURNAL, Robles-De-La-Torre G, Hayward V, Force can overcome object geometry in the perception of shape through active touch, Nature, 412, 6845, 445–8, 2001, 11473320,weblink 10.1038/35086588, ]
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[the MIT Technology Review article "The Cutting Edge of Haptics"]
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[BOOK, Fix, James D., Neuroanatomy, Lippincott Williams & Wilkins, Hagerstown, MD, 2002, 127, 0-7817-2829-0, ]
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[WEB,weblink Chapter 7A: Somatosensory Systems, 2008-04-10, ]
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[Introduction to Neurology, 2nd Edition 1976, A.C.Palmer, Blackwell Scientific, Oxford]
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[Sacks, O.. "The Disembodied Lady", in The Man Who Mistook His Wife for a Hat and his autobiographical case study A Leg to Stand On.]
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[The Proprioceptor System]
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[JOURNAL, Ehrsson H, Kito T, Sadato N, Passingham R, Naito E, Neural substrate of body size: illusory feeling of shrinking of the waist, PLoS Biol., 3, 12, e412, 2005, 16336049, 10.1371/journal.pbio.0030412, ]
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[JOURNAL, Robles-De-La-Torre G, The Importance of the Sense of Touch in Virtual and Real Environments, IEEE Multimedia, 13, 3, 24–30, 2006, 10.1109/MMUL.2006.69,weblink ]
External links
{{Somatosensory system}}
TiefensensibilitätPropiocepciónProprioceptionPropriocezioneProprioceptiePropriocepcjaPropriocepçãoКинестезияProprioceptionAsentoaistiProprioception肌肉運動知覺
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