People who had lost the ability to speak due to an injury to the brain or spinal cord are sometimes offered a special device that allows them to use head, eye or cheek movements to type letters on a screen – a method also used by the famous theoretical physicist Stephen Hawking.
Even though the importance of these devices to people who are no longer able to vocalize could not be overstated, researchers are also developing more advanced equipment capable of interfacing directly with the brain, thereby providing a more intuitive means of communication.
While these, more sophisticated, devices are currently a little too slow for widespread adoption, researchers at Stanford University are making significant headway. In a new paper, published in the science journal eLife, they’d managed to improve on the speeds achieved by their colleagues in the past.
Three volunteers – two with motor neuron disease, also known as ALS, and one with a spinal cord injury – were hooked up to a computer via a silicone patch containing a hundred tiny probes that were attached to their primary motor cortex – a part of the brain involved in coordinating bodily movement.
Currently, the bottleneck in brain-machine interface applications is the speed at which a computer can decode the signals coming from the motor cortex and represent them visually by moving a cursor on a screen.
After a day of practice, the participants became proficient enough to write words and form sentences, typing between six and eight words a minute. “It’s two to four times faster than what was previously achieved [using a brain-machine interface],” said study co-author Jaimie Henderson. This amounts to almost half the speed at which people without disability can text.
While the device received positive evaluations from the volunteers, it’s still a ways away from becoming commercially viable.
“This device is great,” said Nicho Hatsopoulos of the University of Chicago in Illinois. “The most impressive thing is the number of characters they could type per minute.” Commenting on the design and market-readiness of the experimental tool, however, he was a little more reserved. “Personally, I’d want something wireless, and proven to last for a long time”.
To reach that level, Henderson and his team will keep working with paralysed people and try to develop a version that anyone in need of speech assistance could have at their own home.