## Mind switch could help disabled regain control

> New Scientist vol 150 issue 2028
> - 04 May 96, page Page 6

> Melbourne

> SEVERELY disabled people could one day use their own brain waves to operate home appliances such as stereos, security systems, lights and telephones, or even scroll through a computer menu of more complex options. The device that might make this possible was unveiled in Australia this week. It works by picking up specific electrical patterns in the brain and using them to control a switch.

> The "mind switch" is the brainchild of a team at the University of Technology in Sydney. Tests on 120 volunteers suggest that at least 95 per cent of the population need no training to operate the device. All users have to do is close their eyes and relax briefly for the change in brain waves to be picked up.

> The university is negotiating with companies in Germany and the US to commercialise the mind switch for the severely disabled. Even toy manufacturers in the US and Japan are interested in its possibilities. The university has applied for an Australian patent on the device and is filing an application for an international patent later this year.

> "It's been known for over 20 years that there are changes in the alpha wave [a component of the EEG] when you relax but no one thought they could use it," says Les Kirkup, the physicist who developed the circuitry that picks out and amplifies the brain signal. "It's been like gold lying on the surface that people have walked over."

> The team discovered the signal two years ago. It comes from the temporal and occipital lobes at the base and back of the brain, and lies in the frequency range between 8 and 13 hertz. The hard part of the project has been to reliably pick up changes in the signal, amplify them and use them to control a switch. The signal is harnessed via electrodes attached to the scalp. The strength of the signal fluctuates between 5 and 15 microvolts and has to be amplified about 150 000 times before it triggers a switch. Electrical signals from muscles, generated if you move your head or grind your teeth, for example, could overpower the signal, so the group had to design sophisticated filters to remove this "noise".

> Both the volunteers and members of the team have used the signal to turn lamps on and off, to operate toy robots, a fan and a TV, and to race slot cars.

> It is not known exactly why brain waves change when people close their eyes and relax for a few seconds. The same changes do not occur if the lights are switched off or a blindfold is put on.

> Two people who work with technology for the disabled are impressed. "The fact that no training is necessary fascinates me," says James Dean from Technical Solutions, a company in Melbourne that makes aids for the disabled. Many devices for severely handicapped people are intrusive and difficult to use.

> "This one promises to be much simpler," says Raelene Smith of the Northcott Society, an organisation that helps disabled young people. There are already other devices available which can be triggered by closing the eyes but they work either by picking up changes in muscles or by the amount of light reflected from the eyelid. They are "prone to false positives and can switch on accidentally when you blink", explains Kirkup.

> The researchers believe they have found a second brain signal at 5 to 8 hertz in the theta part of the EEG spectrum which could also be used as a switch. If two switches can be developed, people could accomplish more complex tasks. A study with 21 volunteers is designed to learn more about the EEG spectrum, from 0.5 to about 50 hertz, and to confirm the existence of the second signal.

> Ian Anderson

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