It is known that brain–computer interfaces record brain activity and translate the information into useful control signals. They can be used to restore function to people with paralysis by controlling end effectors such as computer cursors and robotic limbs. Communication neural prostheses are brain–computer interfaces which control user interfaces on computers or mobile devices, with directly reading brain signals a highly desirable technology.  Now, a study from researchers at Stanford Bio-X develops a brain-computer interface which reads brain signals to drive a cursor moving over a keyboard. The team state that 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.  The study is published in the journal Proceedings of the IEEE.

Previous studies show that other approaches for helping people with movement disorders to 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, Stephen 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.  Earlier studies from the lab tested a communication neural prostheses successfully on people with paralysis, however, the typing was slow and imprecise. The current study tests improvements to the speed and accuracy of the technology that interprets brain signals and drives the cursor.

The current study develops 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.  The algorithms for translating those signals and making letter selections were improved and the combined improvements in typing speed and accuracy tested.  The monkeys testing the technology have been trained to type letters corresponding to what they see on a screen, transcribing passages of New York Times articles or, in one example, Hamlet.  Results show that the technology allows a monkey to type with only its thoughts at a rate of up to 12 words per minute.

Data findings show that the implanted sensor could be stable for several years. The group note that the animals had the implants used to test this and previous iterations of the technology for up to four years prior to this experiment, with no loss of performance or side effects in the animals.  The team state that people using this system would likely type more slowly, while they think about what they want to communicate or how to spell words. They go on to stress that people might also be in more distracting environments and, in some cases, could have additional impairments that slow the ultimate communication rate; therefore, what cannot be quantified is the cognitive load of figuring out which words to say.

The team surmise that their findings demonstrate a communication prosthesis by simulating a typing task with two rhesus macaques implanted with electrode arrays. They go on to add that their results represent the highest known achieved communication rates using a brain–computer interface.  The researchers state that if successful, technologies for directly interpreting brain signals could create a new way for people with paralysis to move and communicate with loved ones.  They conclude that eventually their technology could be paired with the kinds of word completion technology used by smartphones or tablets to improve typing speeds.

Source: Stanford University