A team led by electrical engineer Krishna Shenoy developed technology that detects brain signals to move a cursor. Animals trained to copy text using the technology were able to type at a rate of up to 12 words per minute.
That technology, developed by Stanford Bio-X scientists Krishna Shenoy, a professor of electrical engineering at Stanford, and postdoctoral fellow Paul Nuyujukian, directly reads brain signals to drive a cursor moving over a keyboard. In an experiment conducted with monkeys, the animals were able to transcribe passages from the New York Times and Hamlet at a rate of up to 12 words per minute.
Earlier versions of the technology have already been tested successfully in people with paralysis, but the typing was slow and imprecise. This latest work tests improvements to the speed and accuracy of the technology that interprets brain signals and drives the cursor.
‘Our results demonstrate that this interface may have great promise for use in people,’ said Nuyujukian, who will join Stanford faculty as an assistant professor of bioengineering in 2017. ‘It enables a typing rate sufficient for a meaningful conversation.’
Other approaches for helping people with movement disabilities type involve tracking eye movements or, as in the case of Stephen Hawking, tracking movements of individual muscles in the face. However, these have limitations, and can require a degree of muscle control that might be difficult for some people. For example, Hawking wasn’t able to use eye-tracking software due to drooping eyelids and other people find eye-tracking technology tiring.
Directly reading brain signals could overcome some of these challenges and provide a way for people to communicate their thoughts and emotions.
The technology developed by the Stanford team involves a multi-electrode array implanted in the brain to directly read signals from a region that ordinarily directs hand and arm movements used to move a computer mouse.
It’s the algorithms for translating those signals and making letter selections that the team members have been improving. They had tested individual components of the updated technology in prior monkey studies but had never demonstrated the combined improvements in typing speed and accuracy.
‘The interface we tested is exactly what a human would use,’ Nuyujukian said. ‘What we had never quantified before was the typing rate that could be achieved.’ Using these high-performing algorithms developed by Nuyujukian and his colleagues, the animals could type more than three times faster than with earlier approaches.
The monkeys testing the technology had been trained to type letters corresponding to what they see on a screen. For this study, the animals transcribed passages of New York Times articles or, in one example, Hamlet. The results show that the technology allows a monkey to type with only its thoughts at a rate of up to 12 words per minute.
People using this system would likely type more slowly, the researchers said, while they think about what they want to communicate or how to spell words. People might also be in more distracting environments and in some cases could have additional impairments that slow the ultimate communication rate.
‘What we cannot quantify is the cognitive load of figuring out what words you are trying to say,’ Nuyujukian said.
Despite that, Nuyujukian said even a rate lower than the 12 words per minute achieved by monkeys would be a significant advance for people who aren’t otherwise able to communicate effectively or reliably.
Stanford University news.stanford.edu/2016/09/12/typing-brain-sensing-technology/