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Researchers Seek Ways to
Communicate with "Locked-In" Patients
Part Two of Four By Liz Townsend
Researchers in the United States and Britain are developing techniques to communicate with patients who are unable to speak or move by translating the electrical activity in the brain into words. The hope is that patients diagnosed as in a "persistent vegetative state" (PVS) or "locked-in syndrome," considered conscious but without the ability to communicate, can answer questions using simple words. The techniques use electrocorticography (ECoG)--electrodes placed in the brain--or electroencephalography (EEG)--electrodes placed on the scalp--to measure the electrical activity. While a great deal more work is required, the goal is to create a device that could be used to interpret the brain signals of patients with PVS, stroke, Lou Gehrig's disease, trauma, or paralysis. Bradley Greger, assistant professor of bioengineering, and colleagues at the University of Utah discussed the findings of their ECoG experiment in the October issue of the Journal of Neural Engineering. A patient who was having brain surgery for epilepsy agreed to have micro-electrodes placed on his brain in the areas relating to language and to facial movements that produce sounds. In one-hour sessions over four days, the researchers asked the patient to repeat the words yes, no, hot, cold, hungry, thirsty, hello, goodbye, more, and less. In analyzing the data, they "looked for patterns in the brain signals that correspond to the different words," Greger said in a University of Utah press release. The researchers tried several different ways of comparing the data to see which signals gave the most accurate translation of the words. They found that comparing just one signal to another, using signals from the facial motor cortex, and using data from five specific electrodes produced 85% accuracy. Comparing all the words to each other while using those five electrodes garnered accurate results only 48% of the time. "This is proof of concept," Greger said in the press release. "We've proven these signals can tell you what the person is saying well above chance. But we need to be able to do more words with more accuracy before it is something a patient really might find useful." "We would like to get that from 10 to 50 words and also do the alphabet," Greger told the Salt Lake Tribune. "You could restore a lot of communication." The EEG research is similar, but uses larger electrodes placed outside the brain on the scalp. Neuroscientist Adrian Owen of Cambridge University told The Independent that he will soon publish a journal article about his research using EEG signals. Owen has previously published studies using functional Magnetic Resonance Imaging (fMRI) technology to detect brain activity when PVS patients were asked a series of questions (see www.nrlc.org/news_and_Views/Feb10/nv020410.html). The fMRI technique, while an encouraging development, has several drawbacks: the machines themselves are costly and not portable, and the data needs to be analyzed and cannot be used for a real-time conversation, according to The Independent. Owen's EEG idea would be much more practical. "We are going to get to the position where someone can communicate on a regular basis," he told The Independent. "It will likely involve a set of electrodes which they will wear on their head--an electrode cap--connected to a computer somewhere. It means we can bring it to the bedside and it will be relatively affordable." Owen and several of his Cambridge colleagues have accepted appointments to the University of Western Ontario in Canada, where the government and university have pledged $20 million for a new research program, The Independent reported. They intend to continue work on communicating with brain-injured patients. "We are using brain imaging as a form of action. We ask the patients to activate their brain [by imagining a game of tennis] and when it is repeated over and over, it is convincing evidence that they are conscious," Owen told the newspaper. "We now have a moral responsibility to find ways of allowing them to express themselves. It is technically challenging--you can't put them in the fMRI scanner every time you want to find out if they are feeling pain. I think it is inevitable we will be able to use an EEG-based system before long." |
