URJHS Volume 7

Mechanisms of Embodiment—Insights from Psychiatric and Neurological Disorders, Experimental Procedures and Physical Disability

Thomas Hugh Richardson
Trinity College, Dublin, Ireland

Abstract

A number of factors appear to be important in the development of body image and a sense of embodiment. This paper reviews how neurological and psychiatric disorders, experimental procedures, and physical disability can give insight into the psychological and neurological mechanisms that underlie the development of embodied experience. Five main areas are examined within the paper; psychotic disorders and experiences, eating disorders, neurological and neuropsychiatric disorders, experimental procedures, and phantom limbs and prosthetics.

Introduction

The notion of body image and embodiment is one that has been studied for centuries by a range of different disciplines, such as sociology, neurology, psychology, anthropology, physiology, and philosophy. In the contemporary literature, embodiment is usually used to refer to human’s sense of feeling embodied, that is, our sense of self as being located within one’s body (Arzy et al., 2006a). A body image refers to the mental image we have of the appearance of our body (Traub & Orbach, 1964). This paper will examine contemporary literature from the disciplines of psychology, psychiatry, and neurology, focusing in particular on how disorders of embodiment and disembodied experiences can inform as about the development of normal embodied experience and healthy body image. Five main areas and their relation to body image and embodied experience will be studied: psychotic disorders and experiences, eating disorders, neurological and neuropsychiatric disorders, experimental procedures, and phantom limbs and prosthetics.

Psychotic disorders and experiences

A number of other psychotic disorders and experiences can give insight into embodied experience. Particularly important are psychotic disorders such as schizophrenia. Although auditory hallucinations are the most common type of hallucination, somatic hallucinations can occur in schizophrenia with a wide range of disembodied experiences, in particular the experiencing of one’s body as an object separated from the self (Parnas & Handest, 2003). Patients also often experience changes in bodily experiences, such as feeling that the body is smaller or larger and of different proportions to reality and feelings of expanding and shrinking (Parnas & Handest, 2003). Such somatic hallucinations have been found to relate to activity in the primary somatosensory and posterior parietal cortex (Shergill et al., 2001), and post central gyrus and basal ganglia (Baldeweg et al., 1998). This suggests that such areas of the brain are involved in non-pathological somato-sensory mechanisms. Somatic hallucinations have also been shown in psychosis secondary to epilepsy, again suggesting a neural mechanism for somatic experiences (Takayaa et al., 2005).

An important psychotic experience relating to embodiment is commonly referred to as an out-of-body experience (OBE). These experiences are found not only in clinical populations, but in up to 12 percent of the general population (Blackmore, 1984) and are related to personal perceptual body experiences such as body satisfaction, confidence in physical appearance, and somatoform dissociation (Irwin, 2000; Murray & Fox, 2005). It has been argued that an individual’s body image may be related to OBEs, with changes in body image combining with changes in a body concept developed by proprioceptive information, to create an OBE (Palmer, 1978). A related disorder is that of Depersonalisation Disorder, in which individuals feel detached from their body (APA, 1994). This is commonly related to anxiety disorders, occurring in up to 83 percent of panic disorders (Hunter, Sierra & David, 2004), perhaps due to the resulting impaired cognitions (Hunter et al., 2003), and is commonly co-morbid with unipolar mood disorders (Simeon et al., 1997). This suggests that emotional states and related cognitions are important in maintaining an embodied experience. Depersonalisation also often occurs in temporal lobe epilepsy (Kenna & Sedman, 1965) and is related to fronto-temporal activation (Hollander et al., 1992), suggesting these parts of the brain are important in maintaining a sense of self in the world. Often psychotic disorders relate to a disordered body image. For example, Body Integrity Identity Disorder is characterised by a strong wish to amputate a part of the body (First, 2005). Whilst the part of the body, usually the limb, is healthy, the individual reports that they do not feel complete with this limb and that amputating it would make them feel embodied and whole (Berger et al., 2005). This demonstrates how a sense of embodiment can be discrepant with actual body form, highlighting the importance of a body image in embodied experience.

Eating disorders

Eating disorders, in particular Anorexia Nervosa (AN) and Bulimia Nervosa (BN), give valuable insight into embodied experience, in particular how body images are formed and distorted. These disorders are characterised by a drive for thinness resulting in low food intake, or purging or the use of laxatives to reduce weight accompanied with disturbances in body image (APA, 1994), and have a high prevalence, with 8 percent of adolescent females meeting the criteria for BN (Crowther, Post & Zaynor, 1985). Both men and women have disturbances in body image and want to change their weight, the difference being that generally women want to lose weight and men want to gain weight (Cohane & Pope, 2001) and increase muscle (McCreary & Sasse, 2000).

A body image refers to the mental image we have of the appearance of our body (Traub & Orbach, 1964). Research has consistently shown body image disturbances in eating disorders, for example Garner et al., (1976) found that anorexic women estimated their body mass as significantly higher than their actual mass compared with controls. Anorexic women also tend to considerably overestimate the size of specific part of the body such as the hips and chest (Slade & Russell, 1973), and such body image disturbances are a significant predictor of later disorder eating (Hill, 1993). A more severe variant of body image disturbances in eating disorders is known as Body Dysmorphic Disorder (BDD), characterised by a distressing obsession with a defect in physical appearance that does not actually exist (APA, 1994). The main psychotic element of BDD is the perseverance of a delusional belief about an imagined defect in one’s appearance, despite evidence to the contrary (Phillips et al., 1993). Whilst this is commonly reported in women, in men a related condition called Muscle Dysmorphia has been described, in which muscular men view themselves as thin and weak (Pope et al., 1997). In extreme cases, people can believe that they look like the elephant man or some kind of monster (Phillips, 1996). Such disturbances are not caused by a general perceptual deficit (Cash & Deagle, 1997), suggesting that one’s body image is distorted.

A wide range of research has demonstrated the mechanisms by which eating disorders and body image disturbances can arise. Research has shown that children brought up in state childcare facilities have disturbed body image, highlighting how childhood experiences can effect body image ( Skarderud, Nygren & Edlund, 2005). Poor parenting also predicts disturbed body image (Kent et al., 1991) as does teasing about weight from family and peers (Cattarin & Thompson, 1994; Thompson & Psaltis, 1988). Body image concerns are also related to attitudes of peers towards body image (Gardner, Sorter & Friedman, 1997; Pyle, Mitchell & Eckert, 1981) and a range of other factors such as academic pressure, sexual abuse, negative affect, and early onset of puberty (Thompson & Heinberg, 1999). The media, as a medium for the transmission of social ideals of body image, has been found to have a considerable impact on body image concerns (Stice, 1994; Thompson & Heinberg, 1999). These factors demonstrate a variety of sociocultural and interpersonal mechanisms that can distort body image, thereby giving insight into the processes through which a healthy body image is developed.

Neurological and Neuropsychiatric disorders

A number of neurological and neuropsychiatric disorders have symptoms of disordered embodiment that give valuable information regarding the processes underlying normal embodied experiences. One such disorder is Autotopagnosia (AT), in which a patient is unable to recognise or point to parts of their own body—they are not consciously aware of parts of their body. This condition is often associated with damage to the left parietal lobe (Denes, 1999), and cognitive tests have suggested that it may be caused by an inability to processes the properties of one’s own body parts (Guariglia et al., 2002), leading to an inability to code the position of one’s body parts relative to each other (Schwoebel, Coslett & Buxbaum, 2001), which results in an incomplete or inaccurate representation of one’s body. Such deficiencies have been shown in specific body parts, such as finger agnosia—an inability to differentiate between, name, or recognise one’s fingers (Benton, 1955; Gerstmann, 1940) and the similar condition of toe agnosia (Tucha et al., 1997).

Another neurological disorder of embodiment is Asomatognosia (AS). Often resulting from damage to the right posterior parietal cortex (Arzy et al., 2006b), AS manifests itself as an unawareness of parts of the body, with patients commonly reporting that parts of their body are missing (Arzy et al., 2006a). Rather than a patient feeling completely disembodied, patients usually report that specific parts of their body disappear from their awareness; for example Arzy et al. (2006b) reported the case of a woman who perceived parts of her left arm to be invisible, and Wolpert, Goodbody & Husain (1998) reported on a patient whose right limbs felt as if they were drifting away from her body whenever she wasn’t looking at them. AS is often temporarily alleviated by looking at or touching the missing limb, suggesting that our sense of embodiment is made up of multisensory representations (Newport, Hindle & Jackson, 2001). A related condition is Somatoparaphrenia, often caused by damage to the right parietal lobe, in which patients believes that one of their limbs does not belong to themselves, often claiming that it is someone else’s limb (Halligan, Marshal & Wade, 1995).

The differences between objective ability and a subjective sense of embodiment are further demonstrated by the condition Anosognosia for Hemiplegia, often occurring after a stroke causes damage to the parietal and frontal lobes (Pia et al., 2004). In this case a patient denies that a recently paralysed limb is in fact paralysed (Papagnoa & Vallar, 2003). This condition is also often accompanied by illusory movements of the limb in question (Feinberg, Roane & Ali, 2000). Other neurological and neuropsychiatric conditions which give insight into disembodied experience includes Autoscopic Hallucinations, a sense of viewing a reflection of one’s own body (Zamboni et al., 2005), Alloesthesia, in which a patient perceives stimulus as being on the opposite side of the body to reality (Ortigue et al., 2005), and Macrosomatognosia and Microsomatognosia, in which the patients feel that parts of their body, or their whole body, are abnormally large or small (Podoll et al., 1998). There are even very rare cases where individuals can completely lose their sense of proprioception, essentially becoming completely disembodied (Sacks, 1985). Such neurological and neuropsychiatric conditions give insight into the mechanisms underlying disembodied, and therefore embodied experience, and in particular the neurological correlates of such experiences.

Experimental findings

An important way of studying embodied experience is through the use of laboratory-based experimental research, usually conducted with normal populations. Such procedures can be used to manipulate embodied experience, thereby giving insight into the ways in which our embodied experiences are formed. One such procedure is the “rubber hand procedure”(Botvinick & Cohen, 1998). In this procedure subjects are seated with their left arm resting on a table, a screen is placed beside the arm to hide it from view, and a rubber model of the hand is placed on the table in front of the subject. The subject is asked to stare at the rubber hand while the real hand and the rubber hand are stroked with a brush. After a few minutes, the subject begins to feel the touch not of the hidden brush on their actual arm, but of the viewed brush on the rubber arm, as if the rubber arm sends the touch. This illusion provides evidence in favour of the visual bias of proprioception (Hay, Pick & Ikeda, 1965) and suggests that our vision is crucial to embodied experience. Another relevant experimental procedure is the Pinocchio Illusion , which gives the illusion of the nose growing. This procedure has been demonstrated to manipulate experiences of the height, width, and shape of various body parts (Lackner, 1988) and gives valuable insight into the mechanisms underlying somatosensory and proprioceptive feedback.

Experimental procedures have also been used to produce OBEs and other illusions of embodied experience. For example, head-mounted video, displaying a different perspective on one’s own body has been used to produce feelings of dissociation from one’s body (Miller, 2007), demonstrating the importance of visual information in creating an embodied experience. Laboratory studies have found that techniques such as relaxation, sensory deprivation, and manipulating mental imagery of ones own body can all induce OBEs (Blackmore, 1982), and electrical simulation of parts of the brain has also been found to alter embodied experience. For example Blanke et al. (2002) used electrical stimulation of the right angular gyrus to induce an OBE in an epilsepy patient. Transcranial magnetic stimulation (TMS) to the cerebellum has also been found to produce illusory body experiences (Schutter et al., 2006). Such experimental procedures have been crucial to our understanding of embodiment, demonstrating the cognitive, perceptual, and neurological mechanisms crucial to embodied experience.

Phantom limbs and prosthetics

Phantom limbs and the use of prosthetic limbs are an intriguing way to demonstrate the role of body image in our sense of embodiment. Phantom limbs can occur for many parts of the body, such as the penis (Heusner, 1950), rectum (Dorpat, 1971), face (Sacks, 1992), and breast (Weistein, Vetter & Sersen, 1970), but are most commonly reported in limbs. Phantom limbs occur when an individual has had a limb removed, after which the limb can still be felt in terms of movement, touch, temperature, and pain (Ramachandran & Hirstein, 1998). Such phantom limbs are experienced by up to 98 percent of amputees (Ramachandran & Hirstein, 1998). Phantom limbs are general perceived to be of normal shape, size, and posture (Giummarra et al., 2007), but may often adopt the position prior to amputation, such as in a sling (Katz, 1992), and can be felt as being in unusual postures, such as legs being crossed or twisted (Bors, 1951). Phantom limbs are felt as so real by those who experience them that they often forget that is not real and try to use it, for example trying to break a fall (Giummarra et al., 2006a). There are reports of phantom limbs in those born without limbs, suggesting that we are born with a neural representation of our body image (Ramachandran & Hirstein, 1998). Similar insight into the neural mechanisms of embodiment is given by the finding that phantom limb experiences are related to the change in the somatosensory and motor cortex (Grusser et al., 2001; Hall et al., 1990 ). Over time, the neural representation of the lost limb is taken over by other parts of the brain (Ramachandran & Hirstein, 1998), suggesting that neural plasticity may enable our body image to change over time. Factors that influence the onset and maintenance of phantom limbs, such as passive coping and negative affect (Richardson et al., 2007), and whether the loss is sudden or traumatic (Ramachandran & Hirstein, 1998) demonstrate the importance of past experiences and emotional states in maintaining a complete sense of embodiment.

Prosthetic devices are commonly used in individuals who have lost a limb and give valuable insight into how our sense of embodiment is formed, in particular how it can go beyond our physical boundaries. During prolonged use, the tool, such as a walking stick, can become incorporated into the body schema (Gallagher & Cole, 1995), such that it feels like extensions of the arm itself (Yamamoto & Kitazawa, 2001). Such an effect can also be found with prosthetic devices (Lewis, 2006), where the body’s sense of proprioception is extended to the prosthetic, such that individuals may be able to touch-type with a prosthetic hand (Tsukamoto, 2000). After using a prosthesis for many years, individuals report that they experience their body as being whole and that the prosthesis is part of them (Murray, 2004), suggesting that our sense of embodiment relies on more than just our physiological proprioception. Whilst wearing a prosthesis, it is reported that phantom’s disappear (Andre et al., 2001), such that scratching a prosthesis can relive a phantom itch (Giummarra et al., 2006b). The phenomena of phantom limbs, and the way in which prosthetic limbs can become embodied, gives insight into the neural, emotional, and developmental mechanisms that help to develop and maintain our sense of embodiment.

Conclusion

This paper has focused on the ways in which psychiatric and neurological disorders, experimental procedures, and physical disability can give insight into the mechanisms by which body image and a sense of embodiment develop. Psychotic disorders and experiences such as OBEs give an insight into the psychological and neural mechanisms through which disembodied experiences can occur. Eating disorders demonstrate the wide range of societal and interpersonal factors that can affect our body image. Neurological and neuropsychiatric conditions of disordered embodiment demonstrate the neural mechanisms responsible for creating our sense of self and embodiment in the world. Experimental findings show how such experiences can be manipulated, giving further insight into the mechanisms of body image. Phantom limbs and prosthetics give a particularly valuable insight into how our sense of embodiment changes over time. Overall, these findings demonstrate the wide range of complex psychological and neurological mechanisms that help to maintain a health body image and sense of embodiment.

References

American Psychiatric Association. (1994). Diagnostic and statistical manual of mental disorders (4th ed.). Washington, D.C.

Andre, J. M., Martinet, N., Paysant, J., Beis, J. M., & Le Chapelain, L. (2001). Temporary phantom limbs evoked by vestibular caloric stimulation in amputees. Neuropsychiatry, Neuropsychology, and Behavioural Neurology, 14(3), 190–196.

Arzy, S., Thut, G., Mohr, C., Michel, C. M., & Blanke, O. (2006a). Neural basis of embodiment: distinct contributions of temporoparietal junction and extrastriate body area. The Journal of Neuroscience, 26 (31), 8074–8081.

Arzy, S., Overney, L. S., Landis, T., & Blanke, O. (2006b). Neural mechanisms of embodiment: Asomatognosia due to premotor cortex damage. Archives of Neurology, 63, 1022-1025.

Baldeweg, T., Spence, S., Hirsch, S. R., & Gruzelier, J. (1998). Gamma-band electroencephalographic oscillations in a patient with somatic hallucinations. Lancet, 352, 620–1.

Benton, A, L. (1955). Development of finger localization capacity in school children . Child Development, 26, 225-230.

Berger, B, D., Lehrmann, J. A., Larson, G., Alverno, L., & Tsao, C. I. (2005). Nonpsychotic, nonparaphilic self-amputation and the internet. Comprehensive Psychiatry, 46(5), 380–383.

Blackmore, S. J. (1984). A postal survey of OBEs and other experiences. Journal of the American Society for Psychical Research, 52, 225–244.

Blackmore, S, J. (1982) Beyond the body. An investigation of out-of-body experiences. Heinemann, London, 1982.

Blanke O., Ortigue, S., Landis, T., & Seeck, M. (2002). Stimulating illusory own-body perceptions. Nature, 419(19), 269-70.

Bors, E. (1951). Phantom limbs in patients with spinal cord injury. Archives Neurology Psychiatry, 66, 610–631.

Botvinick, M., & Cohen, J. (1998). Rubber hands ‘feel’ touch that eyes see. Nature, 391(19), 756.

Cash, T. F., & Deagle, E. A. (1997). The Nature and Extent of Body-Image Disturbances in Anorexia Nervosa and Bulimia Nervosa: A Meta-Analysis. Int J Eat Disord, 22, 107–125.

Cattarin, J. A., & Thompson, K. J. (1994). A Three-Year Longitudinal Study of Body Image, Eating Disturbance, and General Psychological Functioning in Adolescent Females. Eating Disorders, 2(2), 114-125.

Cohane, G. H., & Pope, H. G. (2001). Body image in boys: A review of the literature. International Journal of Eating Disorders, 29, 373–379.

Crowther, J. H., Post, G., & Zaynor, L. (1985). The prevalence of bulimia and binge eating in adolescent girls. International Journal of Eating Disorders, 4(1), 29-42.

Denes, G. (1999). Disorders of body awareness and body knowledge. In: Denes, G. & Pizzamiglio, L. (Eds.) Handbook of clinical and experimental neuropsychology. Hove: Psychology Press, 1999: 497–506.

Dorpat, T. L. (1971). Phantom sensations of internal organs. Comprehensive Psychiatry, 12 , 27-35.

Feinberg, T. E., Roane, D. M., & Ali, J. (2000). Illusory limb movements in anosognosia for hemiplegia J. Neurol. Neurosurg. Psychiatry, 68, 511-51.

First, M. B. (2005). Desire for amputation of a limb: paraphilia, psychosis, or a new type of identity disorder. Psychological Medicine, 35, 919–928.

Gallagher, S., & Cole, J. (1995). Body image and body schema in a deafferented subject. Journal of Mind and Behaviour, 16, 369–390.

Gardner, R. M., Sorter, R. G., & Friedman, B. N. (1997). Developmental changes in children’s body images. Journal of Social Behavior and Personality, 12, 1019–1036.

Garner, D. M., Garfinkel, P. E., Stancer, H. C., & Moldofsky, H. (1976). Body Image Disturbances in Anorexia Nervosa and Obesity. Psychosomatic Medicine, 38(5), 327-328.

Gerstmann, J. (1940). The syndrome of finger agnosia, disorientation for right and left, agraphia and acalculia. Archives of Neurology, Neurosurgery and Psychiatry, 44, 398-408.

Giummarra, M, J., Georgiou-Karistianis, N., Gibson, S, J., Chou, M. & Bradshaw, J, L. (2007). Phantom limbs and the body schema. Paper presented at the IBRO World meeting, Melbourne, Australia, 12–17 July.

Giummarra, M. J., Georgiou-Karistianis, N., Gibson, S. J., Chou, M., & Bradshaw, J. L. (2006a). The menacing phantom: what triggers phantom limb pain and why? Paper presented at the Australasian Winter Conference on Brain Research, Queenstown, New Zealand.

Giummarra, M. J., Georgiou-Karistianis, N., Gibson, S. J., Chou, M. & Bradshaw, J, L. (2006b). Embodied pain: the interaction between prosthesis use and phantom pain. 30th Annual Scientific Meeting of the International Society for Prosthetics and Orthotics, Australian National Member Society, Fremantle, WA.

Grusser, S, M., Winter, C., Muhlnickel, W., Denke, C., Karl, A., Villringer, K., & Flor, H. (2001). The relationship of perceptual phenomena and cortical reorganization in upper extremity amputees. Neuroscience, 102 , 263-272.

Guariglia, C., Piccardi L., Puglisi Allegra, M. C., & Traballesi, M. (2002). Is autotopagnosia real? EC says yes. A case study. Neuropsychologia, 40, 1744–1749.

Hall, E. J., Flament, D., Fraser, C., & Lemon, R. N. (1990). Non-invasive brain stimulation reveals reorganised cortical outputs in amputees. Neuroscience Letters, 116, 379–86.

Halligan, P. W., Marshal, J. C., & Wade, D. T. (1995). Unilateral somatoparaphrenia after right hemisphere stroke: A case description. Cortex, 31, 173–182.

Hay, J. C., Pick, H. L., & Ikeda, K. (1965). Visual capture produced by prism spectacles. Psychon Sci, 2, 215-6.

Heusner, A. P. (1950). Phantom genitalia. Transactions of the American Neurological Association, 75, 128-131.

Hill, A. (1993). Pre-adolescent dieting: Implications for eating disorders. International Review of Psychiatry, 5, 87–100.

Hollander, E., Carrasco, J. L., Mullen, L. S., Trungold, S., De-Caria, C. M., & Towey, J. (1992). Left hemispheric activation in depersonalization disorder: a case report. Biological Psychiatry, 31, 1157-1162.

Hunter, E. C. M., Sierra, M., & David, A. S. (2004). The epidemiology of DP and DR a systematic review. Social Psychiatry and Psychiatric Epidemiology, 39, 9–18.

Hunter, E. C. M., Phillips, M. L., Chalder, T., Sierra, M., & David, A. S. (2003). Depersonalisation disorder: A cognitive–behavioural conceptualisation. Behaviour Research and Therapy, 41, 1451–1467.

Irwin, H. J. (2000). The disembodied self: An empirical study of dissociation and the out-of-body experience. Journal of Parapsychology, 64(3), 261–276.

Katz, J. (1992). Psychophysiological contributions to phantom limbs. Canadian Journal of Psychiatry, 37, 282–298.

Kenna, J. C., & Sedman, G. (1965). Depersonalisation in temporal lobe epilepsy and the organic psychoses. British Journal of Psychiatry, 111, 293-299.

Kent, A., Waller, G., & Dagnan, D. (1999). A greater role of emotional than physical or sexual abuse in predicting disordered eating attitudes: The role of mediating variables. International Journal of Eating Disorders, 25, 159–167.

Lackner, J. R. (1988). Some proprioceptive influences on the perceptual representation of body shape and orientation. Brain, 111, 281–297.

Lewis, J. W. (2006). Cortical networks related to human use of tools. The Neuroscientist, 12(3), 211–231.

McCreary, D., & Sasse, D. (2000). An exploration of the drive for muscularity in adolescent boys and girls. Journal of American College Health, 48(6), 297-304.

Miller, G. (2007). Out-of-Body Experiences Enter the Laboratory. Science, 317, 1020-1.

Murray, C, D. & Fox, J. (2005). Dissociational body experiences: Differences between respondents with and without prior out-of-body-experiences. British Journal of Psychology, 96, 441–456.

Murray, C. D. (2004). An interpretative phenomenological analysis of the embodiment of artificial limbs. Disability and Rehabilitation, 26(16), 963–973.

Newport, R., Hindle, J, V., & Jackson, S. R. (2001). Links between vision and somatosensation: vision can improve the felt position of the unseen hand. Current Biology, 11, 975-980.

Ortigue, S ., Jabaudon, D ., Landis, T ., Michel, C. M ., Maravita, A ., & Blanke, O. (2005). Preattentive interference between touch and audition: a case study on multisensory alloesthesia. Neuroreport, 16(8), 865-8.

Palmer, J. (1978). The out-of-body experience: A psychological theory. Parapsychology Review, 9 (5), 19–22.

Papagno, C., & Vallar, G. (2003). Anosognosia for left hemiplegia: Babinski’s (1914) cases. In Code, C., Wallesch, C. W., Joanette, Y., & Lecours, A. R. (Eds.). Classic Cases in Neuropsychology , Volume 2. Hove, East Sussex: Psychology Press, 2003.

Parnas, J., & Handest, P. (2003). Phenomenology of Anomalous Self-Experience in Early Schizophrenia. Comprehensive Psychiatry, 44(2), 121-134.

Phillips, K. A. (1996). The broken mirror: Understanding and treating body dysmorphic disorder. New York: Oxford University Press; 1996.

Phillips, K. A., McElroy, S. L., Keck, P. E., Pope, H. G., & Hudson, J. I. (1993). Body dysmorphic disorder: 30 cases of imagined ugliness. American Journal of Psychiatry, 150, 302–8.

Pia, L., Neppi-Modona, M., Ricci, R., & Berti, A. (2004). The anatomy of anosognosia for hemiplegia: A meta-analysis. Cortex, 40 , 367-377.

Podoll, K ., Mühlbauer, V ., Houben, I ., & Ebel, H . (1998). Hypnogogic hallucinations of macrosomatognosia and microsomatognosia [Article in German]. Fortschr Neurol Psychiatr, 66(8), 338-44.

Pope, H. G., Gruber, A. J., Choi, P. Y., Olivardia, R., & Phillips, K. A. (1997). Muscle dysmorphia: An underrecognized form of body dysmorphic disorder. Psychosomatics, 38, 548–557.

Pyle, R. L., Mitchell, J. E., & Eckert, E. D. (1981). Bulimia: A report of 34 cases. Journal of Clinical Psychiatry, 42, 60–64.

Ramachandran, V. S., & Hirstein, W. (1998). The perception of phantom limbs: The D.O. Hebb lecture. Brain, 121 , 1603–1630.

Richardson, C., Glenn, S., Horgan, M., & Nurmikko, T. (2007). A prospective study of factors associated with the presence of phantom limb pain six months after major lower limb amputation in patients with peripheral vascular disease. The Journal of Pain, 8(10), 93-801.

Sacks, O. (1992). Phantom faces. British Medical Journal, 304, 364.

Sacks, O. (1985). The disembodied lady. In Sacks, O. The Man who mistook his wife for a hat, chapter 3, 42-52. Picador, 1985.

Schutter, D. J. L. G., Kammers, M. P. M., Enter, D., & Van Honk, J. (2006). A case of illusory own-body perceptions after transcranial magnetic stimulation of the cerebellum. The Cerebellum, 5(3), 238 – 240.

Schwoebel, J, C., Coslett, H. B., & Buxbaum, L. J. (2001). Compensatory coding of body part location in autotopagnosia: Evidence for extrinsic egocentric coding. Cognitive Neuropsychology, 18(4), 363-381.

Shergill, S. S., Cameron, L. A., Brammer, M. J., Williams, S. C. R., Murray R. M., & McGuire, P. K. (2001). Modality specific neural correlates of auditory and somatic hallucinations. J. Neurol. Neurosurg. Psychiatry, 71 , 688-690.

Simeon, D., Gross, S., Guralnik, O., Stein, D. J., Schmeidler, J., & Hollander, E. (1997). Feeling Unreal: 30 Cases of DSM-III-R Depersonalisation disorder. Am J Psychiatry, 154(8), 1107-1113.

Skarderud, F., Nygren, P. ,& Edlund, B. (2005). Bad Boys’’ Bodies: The Embodiment of Troubled Lives. Body Image and Disordered Eating Among Adolescents in Residential Childcare Institutions. Clinical Child Psychology and Psychiatry, 10(3), 395–411.

Slade, P. D., & Russell, G. F. M. (1973). Awareness of body dimension in anorexia nervosa: cross-sectional and longitudinal studies. Psychol Med, 3, 188-199.

Stice, E. (1994). Review of the evidence for a sociocultural model of bulimia nervosa and an exploration of the mechanisms of action. Clinical Psychology Review, 16, 633–661.

Takaya, S., Matsumoto, R., Namiki, C., Kiyosu, H., Isono, O., Hashikawa, K., Ikeda, A., & Fukuyama, H. (2005). Frontal nonconvulsive status epilepticus manifesting somatic hallucinations. Journal of the Neurological Sciences, 234, 25 – 29.

Thompson, K, J., & Heinberg, L. J. (1999). The Media’s influence on body image disturbance and eating disorder: We’re reviled them ,now can we rehabilitate them? Journal of Social Issues, 55(2), 339-353.

Thompson, J. K., & Psaltis, K. (1988). Multiple aspects and correlates of body figure ratings: A replication and extension of Fallon and Rozin (1985). International Journal of Eating Disorders, 7, 813-817.

Traub, A, C., & Orbach, J. (1964). Psychophysical studies of body-image: The adjustable body distorting mirror. Arch Gen Psychiatry, 11, 53-66.

Tsukamoto, Y. (2000). Pinpointing of an upper limb prosthesis. Journal of Prosthetics and Orthotics, 12(1), 56.

Tucha, O., Steup, A., Christian, S. & Lange, K. (1997). Toe agnosia in Gerstmann syndrome. Journal of Neurology, Neurosurgery and Psychiatry, 63, 399-403.

Weinstein, S., Vetter, R, J., & Sersen, E, A. (1970). Phantoms following breast amputation Neuropsychologia, 8, 185-197.

Wolpert, D. M., Goodbody, S. J., & Husain, M. (1998). Maintaining internal representations: The role of the human superior parietal lobe. Nature and Neuroscience, 1(6), 529–533.

Yamamoto, S., & Kitazawa, S. (2001). Sensation at the tips of invisible tools. Nature and Neuroscience, 4 (10), 979–980.

Zamboni, G., Budriesi, C., & Nichelli, P. (2005). Seeing oneself: A case of autoscopy, Neurocase, 11(3), 212 – 215.