Researchers from Australia announced last week that it is possible to guide people movements by remote control. This technique, known as galvanic vestibular stimulation (GVS), is not new and has been demonstrated for the first time in 1999. But until now, this technique, which uses electrodes placed just below people' ears to remotely stimulate their nerves, led people to lose their balance. As Technology Review reports, the researchers have found a way to avoid this feeling. But there is a trade-off: the volunteers need to walk while watching their feet or the sky. So don't expect remote-controlled humans any time soon. But read more...
Here is how this works according to the Technology Review article.
The devices work by stimulating the vestibular system -- a set of tiny structures just behind the ear that keep the head upright and make the visual world appear steady, even when a person is walking and looking around. Three fluid-filled canals, known as the circular canals, sense rotation of the head, while another structure, the otoliths, sense the direction of gravity. Signals from the vestibular nerve travel to the brain; for example, a greater frequency of signals from one ear signals that the head is moving in that direction.
But even if this technique gave some 'good' results, it also had side-effects, leading the subjects to walk awkwardly.
In the newest incarnation of the technique, scientists at the University of New South Wales in Australia[, led by Richard Fitzpatrick from the University of New South Wales,] found a relatively simple solution to the steering problem. They administered the vestibular stimulations while the volunteers turned their faces toward either the ground or sky. For reasons not entirely understood, this made them pivot cleanly to the left or right when stimulated, without the characteristic dizziness.
In "Blindfolded humans steered by remote control," Nature provides some explanations.
This, the researchers explain, is because their electrical signals have the net virtual effect of rotating the head around an axis running from the back of the head through the nose. When one stands upright, the stimulation makes it feel as though one's head is swaying to one side or the other, as if the ears are moving towards the shoulders. The body then sways to one side to compensate, and the subject loses balance.
But when you tilt your head backwards or forwards, that rotation axis (from the back of the head through the nose) becomes vertical to the floor. Now stimulation makes it feel as though the head is rotated to point to the left or the right, and in turn the participant may feel as if they are accidentally swerving to walk in this direction. To compensate, they start to walk in a curve in the opposite direction.
And New Scientist, in "Understanding how humans walk upright," describes the experiments which were done in Sydney's Botanic Gardens.
Fitzpatrick and his team asked the blindfolded volunteers to bend their necks so their heads faced the ground or the sky, and then to walk to a target straight ahead. They found they could use the electrodes to make the volunteers feel that their body was oriented not towards the target, but towards the left or to the right, so that they steered a veering path in the opposite direction in order to try to compensate. In this way, the researchers directed people around the gardens, without affecting their balance.
However, if the volunteers walked with their heads upright, the electrical stimuli badly affected their balance. This suggests that the brain extracts two strands of information from the signal coming from the semicircular canals -- information about head rotations in the vertical plane is used to control balance, while rotations in the horizontal plane are used to navigate.
For more information, the research work has been published by Current Biology under the title "Resolving Head Rotation for Human Bipedalism" (Volume 16, Issue 15, Pages 1509-1514, August 8, 2006). Access to the abstract is free, but you'll need to pay $30 to read the scientific paper.
So what will be the use of such a technology, which still needs more research?
Technology Review writes that this technique could be used "to make virtual reality environments seems more realistic or to help people with vestibular disorders."
And Fitzpatrick said to Nature that he "is confident that with a bit more work, GVS could be used for flight simulation and virtual-reality games, especially with goggles creating false images for the eyes. He also suggests that the technique might be applied to cure motion sickness."
But if you are subject to vertigo, don't expect to a relief from this technique before a while.
Sources: Emily Singer, Technology Review, August 8, 2006; Richard Van Noorden, Nature, August 7, 2006; Emma Young, New Scientist, August 7, 2006; and various web sites
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