In a trial, four patients with complete locked-in syndrome – who are incapable of making even small eye movements or subtle blinks – were able to respond “yes” or “no” to spoken questions using their thoughts alone. The system detected their responses by measuring changes in blood oxygen levels and electrical activity in the brain.

The breakthrough study was published in PLOS Biology. “The striking results overturn my own theory that people with complete locked-in syndrome are not capable of communication”, said Niels Birbaumer, a neuroscientist at the Wyss Center for Bio and Neuroengineering in Geneva and senior author of the paper. “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.” The brain-computer interface could transform the lives of such patients, allowing them to express feelings and opinions to their loved ones and caregivers.