A Maynooth scientist has discovered a way to help accident victims who lose control of their limbs, writes Dick Ahlstrom
Watching the brain "blush" offers a promising new way for paraplegics to interact with the outside world. It enables the user to simply think about something as a way of answering yes or no or to trigger a switch.
The system was developed at NUI Maynooth in a project headed by Dr Tomás Ward of the department of electronic engineering. It involves collaboration with colleague Dr Charles Markham of Maynooth's department of computer science and Dr Gary McDarby of Media Lab Europe with funding coming from the Higher Education Authority.
"We are interested in brain/computer interfaces," explains Dr Ward who is developing the project with graduate student Shirley Coyle. Their research involves finding new ways to communicate for patients and accident victims who lose the use of their limbs.
Much research work has gone into new communication systems based on reading brain waves generated by thought, but these methods have proved difficult to achieve, explains Dr Ward. The signals can be a problem to read and interpret and the systems are difficult for the patient to use.
"It takes the user months to learn how to use these systems. They take incredible mental energy to use," he says. "We wanted to come up with a simpler approach that worked."
The researchers employed a "totally different modality" simply by shedding a little light on the problem. The light in this case comes in the form of near infrared wavelengths delivered by light-emitting diodes.
The near infrared (NIR) light is akin to that emitted by your television remote control, but has the advantage of being able to penetrate skin and bone easily. It is used to illuminate brain tissue which can then provide information about brain activity, Dr Ward explains.
The whole idea is based on the fact that oxygen demand goes up when different regions of the brain are activated to control thought or motion, says Dr Ward. Specific regions of the brain are associated with particular activities, whether it is moving your hand, counting or speaking.
The NIR in effect illuminates blood cells flowing in the brain, he says. The red blood cells that ferry oxygen throughout the body look slightly different under NIR light depending on whether they hold or have shed their oxygen supply.
Dr Ward's system detects these differences, enabling the researchers to watch brain activity in real time. "You can see as the brain is working it 'blushes' slightly," he explains. "The system sees the brain blushing in different regions as these regions become active."
Coyle developed NIR sensors that rest on either side of the skull over the regions of the brain linked to hand-movement. The sensors could detect brain activity on either side of the brain no matter whether the subject moved their hand or simply thought about doing so.
This represents a convenient way to provide a yes/no or on/off signal with the subject doing no more than thinking of moving their right or left hand. "That gives you a nice little communications device," says Dr Ward. The work provided the first proof that a NIR light source could be used in this way to produce a readable signal of brain activity.
"The problem with the system is it is slow. It takes three to five seconds to get a response," he says. "The great thing though is the learning curve is basically zero." The patient can master use of the system within minutes.
The researchers published their findings recently in the Journal of Physiological Measurement. "We have demonstrated that this in principle works," he says. It opens the way for a company to develop new products based on the technology developed at Maynooth.