After only a short training, people in a coma managed to send targeted signals

Researchers have succeeded in communicating with brain-injured patients who are unconscious. They see enormous potential in this for future treatments.

Patients who lie motionless in bed after a severe brain injury and do not respond to any response are medically considered unconscious. But some of these people may perceive much more of the environment than assumed – and can even communicate.

At least that's what studies by neurologist Jan Claassen from Columbia University in New York show. Together with his colleagues, he developed a brain-computer interface that made it possible to get in touch with the supposedly unconscious people.

"Research has shown that many patients with acute brain injury who appear to be in a coma actually have some level of consciousness, even though they can't speak or move their hands or eyes," says Claassen.

In recent years, scientists have already developed brain-computer interfaces for paraplegics, for example, who can use them to control devices. To do this, a computer chip must be implanted in the surface of their brains in order to convert thoughts into command signals. However, this approach is unsuitable for unconscious patients with a severe brain injury.

Claassen is one of the pioneers who have researched the so-called hidden consciousness. As early as 2019, he used the usual EEG technology and AI to examine the brain waves of unconscious, brain-injured patients. In 15 percent, he discovered signs that there was still consciousness.

These patients were not able to carry out the request to blink their eyes or move their toes. However, activity could be seen in the EEG recordings of their brain waves that indicated that they had tried to follow the prompt and move their muscles.

Medicine speaks of cognitive-motor dissociation (TMD). The brain regions for thinking and action planning are still active, but the signals no longer reach the motor centers. It was shown that patients with TMD have a higher probability of regaining consciousness.

Routine TMD diagnostics are not yet available, but could one day help to estimate the chances of recovery of a brain-injured patient. "We have shown that recognizing hidden states of consciousness has enormous potential for controlling patient care," says Claassen.

Unconscious patients regulate a beep

In the current study, Claassen has now gone one step further by giving patients with a hidden consciousness the opportunity to actually respond to a request. To do this, he used EEG wires, which are routinely attached to the head of an unconscious patient anyway for monitoring.

A beep was played to the patients via headphones. And a voice asked her to control the height of the beep by opening and closing her hands. As in the previous experiments, the patients had the impulse to move their hands.

The brain waves measured in the process were forwarded to a computer, which converted signals accordingly – and increased or lowered the height of the beep. In this way, the patients learned to control the computer – by remembering whether they wanted to close or open their hands, and thus changed the beep.

The researchers now want to further develop the possibilities of communication. "Our goal is to refine the system so that the supposedly unconscious patients can tell their doctors and relatives how they are doing, whether they are in pain or hungry."

If this succeeds, it could fundamentally change the treatment of severely brain-injured people. For many patients who were previously considered unreachable, a direct communication channel to the outside world could be created for the first time.