LONDON • Scientists have developed a brain-computer interface that reads the brain's blood oxygen levels and enables communication by deciphering the thoughts of patients who are totally paralysed and unable to talk.
In a trial of the system on four patients with complete locked-in syndrome - incapable of moving even their eyes to communicate - it helped them use their thought waves to respond "yes" or "no" to spoken questions.
People who are paralysed except for up and down eye movements and blinking are classified as having locked-in syndrome.
If all eye movements are lost, the condition is referred to as complete locked-in syndrome.
Researchers leading this trial said the brain-computer interface (BCI), which is non-invasive, could transform the lives of such patients, allowing them to express feelings and opinions to their loved ones and carers.
Contrary to expectations, the researchers said, the patients reported being "happy" despite their condition.
"The striking results overturn my own theory that people with complete locked-in syndrome are not capable of communication," said Professor Niels Birbaumer, a neuroscientist at Switzerland's Wyss Centre for Bio and Neuroengineering, who co-led the study.
The trial, published in the journal PLOS Biology on Tuesday, involved four patients .
The researchers asked personal questions with known answers, such as: "Your husband's name is Joachim?", and open questions that needed "yes" or "no" answers, such as "Are you happy?"
The BCI technique used technologies called near-infrared spectroscopy and electroencephalography to measure blood oxygenation and electrical activity in the brain.
"The machine records the blood flow... and calculates how (it) changes during "yes" and during "no", and the computer develops an idea, a pattern," Prof Birbaumer told Reuters.
"And after a while, we know what the patient is thinking, when he thinks "yes", or when he thinks "no", and from that we calculate the answer."
The "known" questions elicited correct responses seven times out of 10.
The question "Are you happy?" resulted in a consistent "yes" response from the four people, repeated over weeks of questioning.