after amputation of the breast, extraction of a tooth (phantom tooth pain), or removal of an eye (phantom eye syndrome). acute proprioception is occasionally impaired spontaneously, especially when one is tired. similar effects can be felt during the hypnagogic state of consciousness, during the onset of sleep. one's body may feel too large or too small, or parts of the body may feel 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. proprioceptive illusions can also be induced, such as the pinocchio illusion. 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 amount of the vitamin in the body returns to a level that is closer to that of the physiological norm. 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. 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 or gain) and/or muscle content (bodybuilding, anabolic steroids, catabolisis/starvation). it can also occur in 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. diagnosis impaired proprioception may be diagnosed through a series of tests, each focusing on a different functional aspect of proprioception. the romberg's test is often used to assess balance. the subject must stand with feet together and eyes closed without support for 30 seconds. if the subject loses balance and falls, it is an indicator for impaired proprioception. for evaluating proprioception's contribution to motor control, a common protocol is joint position matching. the patient is blindfolded while a joint is moved to a specific angle for a given period of time and then returned to neutral. the subject is then asked to move the joint back to the specified angle. recent investigations have shown that hand dominance, participant age, active versus passive matching, and presentation time of the angle can all affect performance on joint position matching tasks. for passive sensing of joint angles, recent studies have found that experiments to probe psychophysical thresholds produce more precise estimates of proprioceptive discrimination than the joint position matching task. in these experiments, the subject holds on to an object (such as an armrest) that moves and stops at different positions. the subject must discriminate whether one position is closer to the body than another. from the subject's choices, the tester may determine the subject's discrimination thresholds. proprioception is tested by american police officers using the field sobriety testing to check for alcohol intoxication. 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 mm (0.79 in), while people with 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. training 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 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 reported the case of a young woman who lost her proprioception due to a viral infection of her spinal cord. at first she could not 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. the proprioceptive sense can be sharpened through study of many disciplines. juggling trains reaction time, spatial location, and efficient movement. standing on a wobble board or balance board is often used to retrain or increase proprioceptive abilities, particularly as physical therapy for ankle or knee injuries. slacklining is another method to increase proprioception. standing on one leg (stork standing) and various other body-position challenges are also used in such disciplines as yoga, wing chun and tai chi. the vestibular system of the inner ear, vision and proprioception are the main three requirements for balance. moreover, there are specific devices designed for proprioception training, such as the exercise ball, which works on balancing the abdominal and back muscles. history of study in 1557, the position-movement sensation was described by julius caesar scaliger as a "sense of locomotion". in 1826, charles bell expounded the idea of a "muscle sense", which is credited as one of the first descriptions of physiologic feedback mechanisms. bell's idea was that commands are carried from the brain to the muscles, and that reports on the muscle's condition would be sent in the reverse direction. in 1847, the london neurologist robert todd highlighted important differences in the anterolateral and posterior columns of the spinal cord, and suggested that the latter were involved in the coordination of movement and balance. at around the same time, moritz heinrich romberg, a berlin neurologist, was describing unsteadiness made worse by eye closure or darkness, now known as the eponymous romberg's sign, once synonymous with tabes dorsalis, that became recognised as common to all proprioceptive disorders of the legs. in 1880, henry charlton bastian suggested "kinaesthesia" instead of "muscle sense" on the basis that some of the afferent information (back to the brain) comes from other structures, including tendons, joints, and skin. in 1889, alfred goldscheider suggested a classification of kinaesthesia into three types: muscle, tendon, and articular sensitivity. in 1906, the term proprio-ception (and also intero-ception and extero-ception) is attested in a publication by charles scott sherrington involving receptors. he explains the terminology as follows: the main fields of distribution of the receptor organs fundamentally distinguishable seem, therefore, to be two, namely, a surface field constituted by the surface layer of the organism, and a deep field constituted by the tissues of the organism beneath the surface sheet. the stimulations occurring in deep field is that the stimuli are traceable to actions of the organism itself, and are so in much greater measure than are the stimulations of the surface field of the organism. since in the deep field the stimuli to the receptors are delivered by the organism itself, the deep receptors may be termed proprio-ceptors, and the deep field a field of proprio-ception. today, the "exteroceptors" are the organs that provide information originating outside the body, such as the eyes, ears, mouth, and skin. the interoceptors provide information about the internal organs, and the "proprioceptors" provide information about movement derived from muscular, tendon, and articular sources. using sherrington's system, physiologists and anatomists search for specialised nerve endings that transmit mechanical data on joint capsule, tendon and muscle tension (such as golgi tendon organs and muscle spindles), which play a large role in proprioception. primary endings of muscle spindles "respond to the size of a muscle length change and its speed" and "contribute both to the sense of limb position and movement". secondary endings of muscle spindles detect changes in muscle length, and thus supply information regarding only the sense of position. essentially, muscle spindles are stretch receptors. it has been accepted that cutaneous receptors also contribute directly to proprioception by providing "accurate perceptual information about joint position and movement", and this knowledge is combined with information from the muscle spindles. etymology proprioception is from latin proprius, meaning "one's own", "individual", and capio, capere, to take or grasp. thus to grasp one's own position in space, including the position of the limbs in relation to each other and the body as a whole. the word kinesthesia or kinæsthesia (kinesthetic sense) refers to movement sense, but has been used inconsistently to refer either to proprioception alone or to the brain's integration of proprioceptive and vestibular inputs. kinesthesia is a modern medical term composed of elements from greek; kinein "to set in motion; to move" (from pie root *keie- "to set in motion") + aisthesis "perception, feeling" (from pie root *au- "to perceive"). plants and bacteria although they lack neurons, systems responding to stimuli (analogous to the sensory system in animals with a nervous system, which includes the proprioception) have also been described in some plants (angiosperms). terrestrial plants control the orientation of their primary growth through the sensing of several vectorial stimuli such as the light gradient or the gravitational acceleration. this control has been called tropism. a quantitative study of shoot gravitropism demonstrated that, when a plant is tilted, it cannot recover a steady erected posture under the sole driving of the sensing of its angular deflection versus gravity. an additional control through the continuous sensing of its curvature by the organ and the subsequent driving an active straightening process are required. being a sensing by the plant of the relative configuration of its parts, it has been called proprioception. this dual sensing and control by gravisensing and proprioception has been formalized into a unifying mathematical model simulating the complete driving of the gravitropic movement. this model has been validated on 11 species sampling the phylogeny of land angiosperms, and on organs of very contrasted sizes, ranging from the small germination of wheat (coleoptile) to the trunk of poplar trees. further studies have shown that the cellular mechanism of proprioception in plants involves myosin and actin, and seems to occur in specialized cells. proprioception was then found to be involved in other tropisms and to be central also to the control of nutation. the discovery of proprioception in plants has generated an interest in the popular science and generalist media. this is because this discovery questions a long-lasting a priori that we have on plants. in some cases this has led to a shift between proprioception and self-awareness or self-consciousness. there is no scientific ground for such a semantic shift. indeed, even in animals, proprioception can be unconscious; so it is thought to be in plants. recent studies suggest that bacteria have control systems that may resemble proprioception.