Proprioception Loss: Blinding the MindFrom the Body
by Emily Douglass
Stephen F. Austin State University,Spring 2000
Returnto Perception: Spring 2000 frontpage.
Proprioception can be described as the mind'sawareness of the body. Proprioception provides the central nervoussystem unconscious information about the body (Bluestone, 1992). The"awareness" of our body may be difficult to understand until we havelost our proprioceptive sense. Researchers concerned withproprioception have usually directed their studies toward identifyingin what processes proprioception plays a major role, and whatprocesses may be hindered if proprioception loss is severe.Unfortunately, not much is known about proprioception, or how muchproprioception contributes to functional accuracy (Gordon, Ghilhardi,& Ghez, 1995).
Sherrington (1961) declares that the proprioceptivereceptors, the nerves associated with proprioception, are effectiveat determining changes inside the organism; which is where the term"proprioception" originates. He explains that proprioceptivereceptors are used especially in muscles and their accessory organs.Proprioceptive receptors and some receptors in the labyrinth(equilibrium detector located in the inner ear) work together to formour receptive systems. Finally, Sherrington shares thatproprioception is responsible for continuous reflexes in skeletalmuscles. In other words, proprioceptive receptors are responsible fordetecting when an area of the body is out of its natural state andprompts the muscles to return the area to a resting state.Proprioception may be best understood by looking at cases ofproprioceptive loss.
To illustrate the profound effects of proprioceptiveloss, Oliver Sacks documented a clinical case of a woman who lost allproprioception (1985). Sacks declared that the sense of our bodiesrelies on three things: vision, the vestibular stystem, andproprioception. His client lost all proprioception and could not walkwithout watching her own legs, or talk without listening to her ownvoice. She could not truly determine if she had a body. The patientcould not perform any motor movements most people would deem naturalwithout relying on environmental feedback to achieve the simplestmaneuver. Oliver Sacks' clinical story reflects how much the minddepends on proprioception for even the most rudimentary actions notthought consciously considered. The following research demonstratesthe importance of proprioception.
A group of researchers conducted a study to determinethe deficits caused by the lack of neck and body proprioception(Blouin et. al., 1995). Their experiment consisted of normalindividuals as well as a patient who had permanent and selective lossof neck and whole body proprioception. They determined throughclinical tests that the patient could not "maintain upright posturewithout losing balance [or] perceive passive body rotations with thehead stationary" (p. 2216). They required the subjects to determinethe amount of passive body rotation (they were rotated by someoneelse, while sitting in a chair). When the lights were illuminated,the patient without proprioception could determine how much her bodyhad rotated. However, when the lights were not turned on and she hadno visual cues, her perception of body rotation was disrupted. Theother participants were much more accurate at determining the amountof passive body rotation with and without visual cues than the womanwith proprioceptive loss. Like Oliver Sacks' patient, she neededvisual feedback to determine the position and movement of herbody.
Sainburg, Ghilardi, Poizner, and Ghez's (1995) studyelaborates on the idea that joint proprioception plays a crucial rolein the knowledge of moving limbs. To assess the role ofproprioception and limb movement, the authors had subjects pretend asif they were cutting bread. The action of cutting bread requires aforward motion followed by a reverse motion. The subjects with normalproprioception made the motions in the normal fashion. However, thesubjects who had proprioceptive loss made circular patterns withtheir arms instead of back-and-forth motions. The authors determinedthat proprioception plays a very critical role in the control ofjoints and motion. The patients who had proprioceptive loss were ableto correct the circular motions if they were allowed to look andprogram their motions before they began the cutting demonstration.The authors' research demonstrates the ease of movements thataccurate proprioception allows. The role of proprioception inaccurate movements has been studied extensively.
Gordon et. al. (1995) conducted two sequentialstudies probing the relationship between reaching movements andproprioception. Their first study focused on spatial errors. Theyfound that subjects who had proprioceptive loss had trouble with slowmotion movements. The participants were instructed to point to avisual target presented on a computer screen. They discovered thatsubjects without proprioception had difficulty touching the target ifthey were instructed to touch the target slowly. The authors alsofound that the participants with proprioceptive loss had extensivedirectional errors in comparison to subjects with normalproprioception.
The second phase of the authors' study focused on theconstruct of visual information and accuracy. The experimentersinstructed subjects to use cursors to click on a target presented ona computer screen. A signaling tone sounded, and the subjects were tomake one, swift motion to touch the target without permission toreadjust their aim. The researchers discovered that subjects withproprioception loss could not detect their own accuracy errors whenthe lights were turned off. The researchers deduced that seeing thelimb was needed for the subjects with proprioception difficulties touse the appropriate muscles to perform the tasks (Ghez, Gordon, &Ghilard, 1995). Their combined research clearly presents howimportant visual knowledge of body positions and actions are forpeople who have lost their proprioceptive awareness of their body.The roles of proprioception and vision are demonstrated by thefollowing research.
Rossetti, Desmurget, and Prablanc (1995) conductedresearch to test if vision or proprioception play a bigger role inthe knowledge of body positions. They tested three constructs ofcoding information. The three constructs were vision-to-vision,proprioception-to-vision, and vision-proprioception-to-vision.Vision-to-vision is based on the idea that vision, and vision solelyassists subjects to accurately pinpoint a target in a visual display.Proprioception-to-vision suggests that proprioception alone isresponsible for accurate target location. Finally,vision-proprioception-to-vision insinuates the need for theinteraction of vision and proprioception to accurately locate avisual target. Their method included subjects with normalproprioception and those without proprioceptive sense. They concludedthat the combination of visual and proprioceptive information assistthe subjects in accurately locating the target. Based on theirfindings, the authors declare that proprioceptive information mayweigh more in the localization process than only visualinformation.
Guedon, Gauthier, Cole, Vercher, and Blouin (1998)conducted research to further examine the role of proprioception andlimb movement. They designed their experiment to include a moredynamic motion of the arms that would be seen in real-lifecircumstances. The subjects were instructed to track a trajectorypresented to them on a computer screen placed one meter away fromtheir seats. The authors recorded the subjects' ability to accuratelyfollow the trajectory of a circular moving target with their arm ofchoice. The researchers designed the apparatus to alternate the ratioof arm movement to relative tracking movement to emphasize trackingmotions one might experience in daily life. The experimenterscompared the results of seven control subjects to one subject withproprioception loss. The results showed that subjects useproprioception to adjust their tracking when the visual cue of theirtracking changed on the screen. The subjects would look at their armand adjust their tracking movements to correlate with what they sawon the screen.
Much of the research on proprioception has beendedicated to finding out what actions proprioception hinders orhelps. There have not been many research designs constructed todiscover how to help those with proprioceptive loss. Oliver Sacks(1995) describes the rehabilitation of his patient as teaching herhow to use visual and auditory feedback to control the body asproprioception used to do. Rossetti et. al. (1995) claim that inpatients deprived of proprioception use vision to help withproprioceptive functions. However, what should happen to a patientwith proprioceptive problems if he or she should go blind? Since mostof the research cited above discusses the use of visual aids incontrolling body movements, sensing body motion, and accuratelyreaching for visual targets, one could only imagine the effects ofblindness on a person who has lost proprioception.
Oliver Sacks (1985) also expressed how his patientused auditory feedback to command her speech. He explains how hispatient was mute until she taught herself to speak again using thesound of her voice to communicate properly. What would happen ifsomeone using the sound of his or her own voice to modulate speechbecame deaf? Proprioception research should not just be dedicated towhat proprioception is responsible for, but how to help those whohave proprioceptive loss. According to Paul Haber (1986) over 80percent of people over the age of 70 have some proprioceptive loss.As our population of elderly grows, problems with proprioception willbecome more prominent. The need for more research in rehabilitativemeasures for people suffering from poor vision and hearing should bevery apparent.
The current research on proprioception provides abackground of information pertaining to what proprioception isresponsible for, assists with, and accompanies. People withproprioception loss may learn new ways to adapt to their lost senses.New methods of rehabilitation could prove fruitful. However, withadvanced technology, the possibility of regenerating damaged sensorynerves should be closer now than ever. Hopefully more research willbe conducted in fixing proprioception loss. Since the majority ofpeople alive today may one day reach the age of 70, researching waysto eliminate the effects of proprioception loss should beinitiated.
Blouin, J. , Vercher, L. J. , Gauthier, G. M. ,Paillard, J. , Bard, C. , Lamame, Y. (1995). Perception of passivewhole body rotations in the absence of neck and body proprioception.Journal of Neurophysiology, 74,(5) , 2216-2219.
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Sainburb, R. L. , Ghilhardi, M. F. , Poizner, H. ,Ghez, C. (1995). Control of limb dynamics in normal subjects andpatients without proprioception. Journal ofNeurophysiology, 73, (2) , 820-835.
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