Don't spell it

The new implant reads words in the head, turning them into text

Sergey Vasiliev, Naked Science

Someday, brain—computer interfaces will allow us to interact directly with electronics without using either a screen or a keyboard. But such developments are especially valuable for people with limited mobility, paralyzed, for whom brain implants can become the only window into the world. Scientists are gradually getting closer to this goal. There are already devices that allow you to write literally "with the power of thought."

As a rule, they read the activity of neurons in the motor cortex while the patient mentally types it on the keyboard or imagines the process of writing by hand. In contrast, the new system requires you to concentrate only on pronouncing words and turns them into text itself, and in different languages. Scientists from the California Institute of Technology presented it at the annual meeting of the American Society of Neuroscience, which is taking place these days.

The system uses a device that is implanted in the left supraorbital gyrus (Brodman field 40). This area of the cortex is responsible for speech analysis, and its damage leads to receptive aphasia — the inability to recognize words. In addition, it is closely related to vocalization, helping to choose words by putting them into phrases. It was here that scientists implanted the Utah array, which includes hundreds of silicon microelectrodes that read the activity of neurons located there.

The subject was a patient with tetraplegia — paralysis of all four limbs. He retained the ability to see, read and talk, which provided scientists with feedback to evaluate the work of his system. The subject was shown a symbol corresponding to one of eight (in another experiment — four) predefined words. After a short pause, he mentally pronounced this word, and then, after a second pause, repeated it aloud.

The signals from the neurons in the supra-marginal gyrus were transmitted to a computer, which interpreted them with fairly decent accuracy. For a set of eight words, it was 72 percent, for four — more than 90 percent. "Our device predicts internal speech directly, allowing the patient to simply focus on pronouncing a word in his head and turning it into text. For many, it can be much easier than trying to pronounce words," she stressed Sarah Wandelt, one of the authors of the development.

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