A man suffering from "locked in" syndrome, where a fully-conscious person is completely paralyzed except for some eyelid movements, is speaking again using a computer. Doctors report in Nature today that he's using a brain implant to control speech synthesizing software with his mind. Though it is often difficult to tell when somebody with locked in syndrome is fully conscious, a team of doctors led by Frank Guenther of Boston University strongly suspected that the man was aware and longed to speak. They put their patient in an fMRI brain scanner and asked him to attempt to make vowel sounds. His brain showed the exact same patterns as an uninjured person making those sounds aloud. So they knew his brain's speech centers were still functioning. They just needed a way to connect those speech centers to a speech synthesizer - an artificial mouth if you will. Researchers implanted a special kind of electrode in his brain, one that's "impregnated with neurotrophic factors" that encourage brain neurons to grow into and around the electrode. Essentially this electrode forms a very strong connection with brain neurons, which results in a strong signal that reliably comes from the same part of the patient's brain over time. Over a period of weeks, Guenther and his team worked to decode the signals coming from the man's brain. Eventually, he was able "to produce three vowel sounds with good accuracy," said Guenther. The man produces these sounds as quickly as he would normal speech, and Guenther added, "The long-term goal within five years is to have him use the speech brain–computer interface to produce words directly." According to Nature:

Their efforts are appreciated by the patient too. "When we first arrived to install this system he was obviously very excited — you can tell from his involuntary movements, and he was trying to look at us the whole time," Guenther says. As the man's father told the team, "he really has a new lease on life". The team's next step is to train their computer decoder to recognize consonants so that patients can form whole words, and even sentences. They also hope that with developments in technology, they can implant more electrodes in their next patient to transmit a more detailed signal.


Other researchers are working on less-invasive techniques to achieve the same goal for other paralyzed patients. Their brain-computer interfaces sit on the outside of the skull, so there's no need to put an electrode into the brain itself. Brain Implant Allows Mute Man to Speak [via Nature] Image via Getty.