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protection of individuals correcting the misalignment
of their brains and their anatomical sex, while supporting their transition
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Body Ownership and Sense of Self Print E-mail
SciMed - Neuroscience
TS-Si News Service   
Sunday, 07 September 2008 17:30

Rubber Hand Illusion

Oxford, UK. People who haven't been there often talk about corrective surgery as though new genitals are "reshaped" or "fashioned" to achieve an approximation of the "real" thing. However, we do know that the surgery uses tissues with clear parallels to the target sexual configuration and the resulting organs are regularly replaced at the cellular level.

The techniques used by the most proficient surgeons to achieve the corrected genital configuration for females have shown excellent results. Surgery for males lags behind, but promising new develops may eventually bring the two types of corrective surgery into general parity.

Function and cosmetics aside, there is more to do. If you do have corrective surgery on your genitals, integrating the new penis, vagina, or other organs into your sense of self and body ownsership is part of the task. There are recorded cases of individuals who skip the standard preparatory stages, opt for surgery, and then have difficulties with psychological and social adjustment. Well-adjusted post-ops appear to do this with little apparent effort. But how is it done?

The implications are wide-ranging, with possible next steps that include a new look at amputations, as well as complex plastic and reconstructive surgeries.Rigorous research on this subject is virtually non-existent. However, some parallel investigations in recent years have illuminated the interplay between our bodies and minds to enable this integration.

Body ownership is a fundamental aspect of human self-awareness – the feeling that your body belongs to you and is constantly there. It is known that this important sense of self can be disrupted in a range of different neurological, psychiatric and psychological conditions (e.g., anorexia, in autism, bulemia, epilepsy, schizophrenia, and after a stroke.

By examining the underlyng mechanisms, scientists at the University of Oxford have constructed an illusion under controlled conditions that can directly address sense of self questions. They can trick people into believing that a substitute extremity actually belongs to them.

Rubber Hand Illusion

The Rubber Hand Illusion

A rubber hand is placed in front of the participant in their field of vision and near to their real hand. A partition conceals the real hand.

If the real and rubber hands are simulataneously touched or stroked in the same way, the participant tries to co-ordinate what they are feeling (stroking on their own hand) and seeing (stroking on the rubber hand).

The subject experiences a shift in where they believe their hand is in relation to the position of the rubber hand.
The experiments show that acceptance isn't all in the mind. The researchers have observed a physical response as well, a finding that offers insight into conditions which affect a patient’s sense of self and body ownership.

Dr. G Lorimer Moseley of the Department of Physiology, Anatomy and Genetics at the University of Oxford.

"People experience this weird illusion," says Dr. G Lorimer Moseley of the Department of Physiology, Anatomy and Genetics at the University of Oxford.

"They will say things like, 'I feel like I own the rubber hand'”.

Dr. Moseley, along with Professor Charles Spence of the Department of Experimental Psychology and researchers in Italy and The Netherlands, pubished their report in the journal PNAS.

Professor Charles Spence of the Department of Experimental Psychology, Anatomy and Genetics at the University of Oxford.

The authors note that incorporating the rubber hand into our sense of self comes at a physical cost. It is as though they are "disowning" the real hand, resulting in a measurable temperature drop in that hand.

‘The rubber-hand illusion is a beautiful device to manipulate our sense of self," Dr Moseley says.

"It tells us that our sense of our bodies, our sense of who we are, is labile (i.e., unstable or not fixed)."

People suffering from complex regional pain syndrome can experience significant distortion in their sense of their physical self. They can disown a limb, feeling that it does not belong to them or that a limb is bigger than it really is.

Many conditions characterised by distortions of body image or ownership are also characterised by a disruption of temperature in one side of the body or a single limb.

"We wanted to see if we could replicate any of this experience. We wanted to see if we could manipulate our sense of ownership of our bodies and reproduce a temperature disruption," says Dr Moseley. "That is exactly what we saw."

"Our sense of our physical self comes from what we’re born with and the constant messages the brain receives from all parts of our bodies. We’ve now shown that this is a two-way street. The mind can also influence the body’s tissues. We have demonstrated that the mind can control a specific body part."

The implications are wide-ranging, with possible next steps that include a new look at amputations, as well as complex plastic and reconstructive surgeries.

CitationPsychologically induced cooling of a specific body part caused by the illusory ownership of an artificial counterpart. G. Lorimer Moseley, Nick Olthof, Annemeike Venema, Sanneke Don, Marijke Wijers, Alberto Gallace, and Charles Spence. PNAS 105(35) 13169-13173. doi: 10.1073 / pnas.0803768105
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Abstract

The sense of body ownership represents a fundamental aspect of our self-awareness, but is disrupted in many neurological, psychiatric, and psychological conditions that are also characterized by disruption of skin temperature regulation, sometimes in a single limb. We hypothesized that skin temperature in a specific limb could be disrupted by psychologically disrupting the sense of ownership of that limb. In six separate experiments, and by using an established protocol to induce the rubber hand illusion, we demonstrate that skin temperature of the real hand decreases when we take ownership of an artificial counterpart. The decrease in skin temperature is limb-specific: it does not occur in the unstimulated hand, nor in the ipsilateral foot. The effect is not evoked by tactile or visual input per se, nor by simultaneous tactile and visual input per se, nor by a shift in attention toward the experimental side or limb. In fact, taking ownership of an artificial hand slows tactile processing of information from the real hand, which is also observed in patients who demonstrate body disownership after stroke. These findings of psychologically induced limb-specific disruption of temperature regulation provide the first evidence that: taking ownership of an artificial body part has consequences for the real body part; that the awareness of our physical self and the physiological regulation of self are closely linked in a top-down manner; and that cognitive processes that disrupt the sense of body ownership may in turn disrupt temperature regulation in numerous states characterized by both.

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TS-Si is dedicated to the acceptance, medical treatment, and legal protection of individuals correcting the misalignment of their brains and their anatomical sex, while supporting their transition into society as hormonally reconstituted and surgically corrected citizens.


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Last Updated on Wednesday, 14 July 2010 22:41