IDENTIFYING telltale brain patterns promises to usher in a new era in which all manner of objects can be controlled by thought. But telling brain patterns apart is devilishly difficult. Now cybernetics researchers think a mild buzz from the gadgets that make phones vibrate will focus the mind.
Controlling electric wheelchairs using the power of the mind is emerging as a realistic option for some people with neurodegenerative conditions such as Lou Gehrig鈥檚 disease. Several groups have already developed such thought-controlled wheelchairs, including 鈥榮 team at the University of Essex in Colchester, UK. His system involves wearing an electrode-filled skullcap connected to a PC running brain-computer interface (BCI) software. This can sense four types of thoughts, represented by electroencephalogram (EEG) potentials. The user thinks about their feet to move forwards, their tongue to stop, and their right or left hands to proceed in those directions.
But being able to move in only three directions is clearly very limiting. Sepulveda鈥檚 team tried to improve on its design by building powerful artificial intelligence software to identify brain patterns associated with thinking about more complex directions, but success eluded them. 鈥淚t would only get it right about 60 per cent of the time, which is not enough for the real world,鈥� says Sepulveda.
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Now Anne-Marie Brouwer and colleagues at the research organisation in Soesterberg, the Netherlands, believe they may have a more liberating approach. They have developed a system called tactile BCI, which uses a physical sensation to provoke an EEG potential called a P300. This is a specific brain response indicating a person鈥檚 strong interest in a particular stimulus. It gets its name because the signal arises 300 milliseconds after the stimulus.
The researchers placed 12 phone vibrators, positioned like the numbers on a clock, on a belt worn around the wheelchair user鈥檚 waist. These vibrate sequentially for 3 seconds each. If they wearer wants to go, say, in a 4 o鈥檆lock direction, they wait until the appropriate 鈥渢actor鈥� vibrates and then think 鈥渢hat one鈥�. 鈥淭hat generates a P300 and selects the movement direction you want,鈥� says Brouwer.
鈥淚f the user wants to go in a 4 o鈥檆lock direction, they wait for the right vibration and think 鈥榯hat one鈥欌��
Tests with 50 volunteers produced good results. 鈥淎lmost everyone who tried it liked it,鈥� Brouwer says.
Tactile BCI could be an important advance, says Sepulveda. 鈥淚 think Brouwer鈥檚 work will be useful. It explores a whole new channel 鈥� a tactile stimulus instead of a visual or auditory one.鈥�
