Patients suffering from complete paralysis, but with preserved awareness, cognition, and eye movements and blinking are classified as having locked-in syndrome. If eye movements are also lost, the condition is referred to as completely locked-in syndrome. In the trial, patients with completely locked-in syndrome were able to respond "yes" or "no" to spoken questions, by thinking the answers. A non-invasive brain-computer interface detected their responses by measuring changes in blood oxygen levels in the brain. The results overturn previous theories that postulate that people with completely locked-in syndrome lack the goal-directed thinking necessary to use a brain-computer interface and are, therefore, incapable of communication. Extensive investigations were carried out in four patients with ALS (amyotrophic lateral sclerosis, also known as Lou Gehrig's disease) -- a progressive motor neuron disease that leads to complete destruction of the part of the nervous system responsible for movement.
The researchers asked personal questions with known answers and open questions that needed "yes" or "no" answers including: "Your husband's name is Joachim?" and "Are you happy?." They found the questions elicited correct responses in seventy percent of the trials. Researchers found that all four patients they tested were able to answer the personal questions they asked them, using their thoughts alone. The question "Are you happy?" resulted in a consistent "yes" response from the four people, repeated over weeks of questioning. The brain-computer interface in the study used near-infrared spectroscopy combined with electroencephalography (EEG) to measure blood oxygenation and electrical activity in the brain. While other brain-computer interfaces have previously enabled some paralyzed patients to communicate, near-infrared spectroscopy is, so far, the only successful approach to restore communication to patients suffering from completely locked-in syndrome.