The Butterfly Revisited: New Eye Scan Could Let Fully Paralyzed People Communicate With Their Pupils [VIDEO]
In the 1997 memoir The Diving Bell and the Butterfly, French journalist Jean-Dominique Bauby recounts in gripping detail how a stroke left him severely paralyzed with locked-in syndrome. Following his brain injury, the former editor-in-chief at Elle magazine famously composed his autobiography, which was later dramatized into a film in 2007, over the course of 10 months by communicating via the blinking of his left eyelid (essentially his only remaining motor function).
New smart goggles from Germany offer a new mode of communication for victims of brain injury like Bauby by allowing them to quickly answer questions with just the pupils in their eyes. It also enables people in a minimally conscious state to respond to commands, making it possible to diagnose patients whose state of consciousness is in question.
As you probably know, your pupils expand and contract in response to light and dark. However, their sizes can also fluctuate while you are thinking, especially while making a decision.
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"It is remarkable that a physiological system as simple as the pupil has such a rich repertoire of responses that it can be used for a task as complex as communication," said author Dr. Wolfgang Einhäuser, a neurophysicist at Philipps-Universität Marburg in Germany.
Einhäuser and his colleagues started this project by asking healthy people to solve a math problem — such as, "are you 20 years old? — while the correct answer — yes or no — was flashed in front of them on a computer screen. Each subject wore a special set of glasses that recorded pupil dilation.
The researchers found that mere contemplation caused an increase in pupil size when a person recognized the correct answer.
The system, which is small enough to fit on a bedside table, was then tested in seven patients with locked-in syndrome. Three of the patients had great success with the system, with accuracy levels that ranged between 67 and 84 percent, which is significantly better than a chance answer.
Three more had success rates that were good, but the system's algorithm requires a bit of tweaking to reach the levels seen with the first group.
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More work is needed to improve speed and accuracy, but this is a very promising first-pass trial.
"We find it remarkable that the system worked almost perfectly in all healthy observers and then could be transferred directly from them to the patients, with no need for training or parameter adjustment," Einhäuser concluded.
"For patients with altered state of consciousness-those who are in a coma or other unresponsive state-any communication is a big step forward," he said.
Source: Stoll J, Chatelle C, Carter O, Koch C, Laureys S, Einhäuser W. Pupil responses allow communication in locked-in syndrome patients. Current Biology. 2013.