Scientists have developed mind-reading technology that can understand people's thoughts without the need for them to speak or even move.
The new non-invasive technology, which is able to interpret answers to questions by detecting changes of blood oxygen levels in the brain, offers the possibility that patients paralysed by injuries, motor-neurone diseases and a range of other conditions will be able to communicate again.
In a pioneering experiment, four people who were incapable of moving their eyes, were able to respond with "yes" or "no" answers. On seven out of 10 occasions the patients said they were happy despite their condition, which requires round-the-clock care.
"The striking results overturn my own theory that people with complete locked-in syndrome are not capable of communication," said Professor Niels Birbaumer, from the Wyss Center for Bio and Neuroengineering in Geneva.
"If we can replicate this study in more patients I believe we could restore useful communication in completely locked-in states for people with motor neuron diseases."