The dream of many of paralysed people, computer-game designers 鈥� and pornographers 鈥� is one step closer to reality with the demonstration of a technique that allows people to physically identify with a virtual body. Virtual bodies become a reality.

The achievement builds on previous work in which neuroscientists created something similar to out-of-body experiences in healthy volunteers and tricked people viewing their virtual body into feeling that body being touched.

In the latest experiment, vibrating pads with flashing lights were positioned on the subjects鈥� backs. Virtual bodies were generated by a camera filming their backs and were viewed as though 2 metres in front of the subjects through a head-mounted display. Repeated stroking of their backs, and the sight of the doppelganger being stroked, created the feeling that they were outside of their bodies.

At the same time, the subjects saw flashes on their virtual bodies, and felt vibrations on their real bodies. Participants were asked to ignore the flashing lights and only report where the vibrations were by pressing a button as fast as possible. The extent to which the flashing light interfered with the reporting of the vibrations was an indicator of where subjects perceived the spatial location of the vibrations to be.

Some volunteers had out-of-body experiences and reported that the vibrations were felt in the location where the flash was seen on their virtual body.

鈥楶romising future鈥�

鈥淭his technology, although currently in basic research, seems to have a very promising future for clinical applications in restoring lost motor functions in paralysed people,鈥� says bioethicist at the Institute for Ethics and the History of Medicine at the University of T疟bingen in Germany. 鈥淚t鈥檚 important to integrate prosthetics into one鈥檚 self concept鈥� (see also Brain could adapt well to cyborg enhancements).

Because this work confirms that people can be made to feel that a touch on the real body is a touch on the virtual body, Jane Aspell of the at the Swiss Federal Institute of Technology in Lausanne, who led the study, says: 鈥淭his emerging field has interesting implications for virtual computer gaming, such as making avatars seem more real and increasing presence in the VR environment.鈥�

Aware animals?

Although full out-of-body experiences in the lab remain elusive, the group is now aiming to boost the illusion by inducing the subject to identify more strongly with the virtual body.

The advantage of this technique, in contrast to previous methods that only used questionnaires, is that sensory perception is measured during the test, and these behavioural measures are less biased as they require no higher-order reflection, says Aspell. This means that it might be appropriate to use the method in a clinical setting where some patients report neurological out-of-body experiences, for example.

Modified versions of these experiments could even be used in animals, the authors say 鈥� allowing scientists to look into whether self-consciousness is unique to humans or whether animals have some sense of self. Because the method doesn鈥檛 require the filling in of a questionnaire, animals could possibly be trained to use the equipment.

Journal reference:

Until now, it was thought that SIV infection in chimps did not result in disease. However, after following 94 wild chimps in Gombe Stream National Park in Tanzania for nine years, , of the University of Alabama at Birmingham, and colleagues have shown that SIVcpz, the virus that jumped from chimps to humans as HIV-1, can and does cause an AIDS-like illness.

Over the 9 years of the study, SIVcpz infection caused an increased risk of mortality. 鈥淯p to 41 per cent in adults and 100 per cent in infants, and lower birth rates,鈥� says Hahn, 鈥渂ut we need longer-term follow-up to determine what proportion of infected animals develop an AIDS-like illness.鈥�

Unique opportunity

Hahn suspects that compared to HIV-infected humans, a greater proportion of SIV-infected chimps do not go on to develop fatal disease. 鈥淏ut this is not simple to test because chimpanzees don鈥檛 just walk into clinics and give you a blood sample.鈥�

However, Hahn hopes that future research into animals which have long-term infection without developing an AIDS-like illness will yield insights that will enable us to better tackle HIV infection.

The team believes that these findings provide a unique opportunity to compare the disease-causing mechanisms of two closely related viruses 鈥� SIVcpz and HIV-1 鈥� in two closely related species. Such work has also already yielded information on mortality rates, prevalence and routes of spread of HIV and SIV.

Journal reference: Nature, DOI: 10.1038/nature08200