�鶹��ý

Paralysed people have communicated with their families by thought alone, thanks to a technique that learns to recognise brain activity associated with “yes” or “no”. The method is non-invasive and has enabled completely “locked-in” people to describe their lives as “wonderful”.

The four people involved in the study all have amyotrophic lateral sclerosis (ALS) – a degenerative disorder that causes people to stop being able to control their muscles, until they are unable even to move their eyes.

It has been impossible to know what such completely locked-in people are thinking. “It is assumed that being cut off from communication is one of the worst states a human can be in,” says at the Wyss Center in Geneva.

To find out, Birbaumer and his colleagues have combined two devices that record brain activity. The first, called NIRS, measures blood in active brain regions by passing a beam of light through the head. Alongside this, the team used EEG electrode caps to record brainwave activity, to tell if a person was awake or asleep.

The group trained their device to recognise the brain activity associated with “yes” and “no” by posing simple statements. “We might say, ‘your name is this, you did that in your past’,” says team member Ujwal Chaudhary at the University of Tübingen. It took up to three weeks to train the device to detect “yes” and “no” with 70 per cent accuracy.

Travel plans

At that point, they started asking the four patients questions the team didn’t know the answer to. “We might ask them if they were in pain, or if they wanted to visit a certain place or meet a certain person,” says Chaudhary.

Each question was asked 10 times. If the team’s device recorded a “yes” seven or more times, then they took that as the person’s answer. “One of our patients is a young woman, only 23 years old,” says Birbaumer. “She told us that she wanted to see New York, so now her family is making preparations to take her there. Another woman wanted to visit her brother in Spain.”

“I believe this is very useful,” says at University Medical Center Utrecht in the Netherlands.

Happy all the time

The team used the device to ask the four people if they were happy. “They say that life is wonderful,” says Birbaumer.

Many people, including some medical professionals, assume that paralysed people have a low quality of life. Birbaumer says that in his experience, this isn’t true.

Some research suggests locked-in people are unable to process negative emotions, says Chaudhary. “They’re only processing positive emotions, and if that happens, you’re basically happy all the time,” he says. “We don’t know why that is, but it seems as though the brain is trying to protect itself.”

The people also gave opinions, for better or worse. One man was asked by his granddaughter if he would give her his blessing to marry a younger man. “Eight times, his answer was no,” says Chaudhary.

Read more: Most ‘locked-in’ people are happy, survey finds