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Ann has been severely paralysed (瘫痪)for more than 18 years. She cannot speak and normally communicates. But now, she has been able to speak through an image on the computer using technology that translated her brain signals into speech and facial expressions.

The advance raises hopes that the technology could be on the edge of transforming the lives of people who have lost the ability to speak due to conditions like strokes (中风).

The latest technology uses tiny electrodes (电极) put on the top layer of the brain to detect electrical activity in the part of the brain that controls speech and face movements. These signals are translated directly into a digital avatar’s (化身) speech and facial expressions including smiling, frowning or surprise.

The team put 253 paper-thin electrodes on the top layer of Ann’s brain over an area important to speech. Afterwards Ann worked with the team to train the system to detect her unique brain signals for various speech sounds by repeating different phrases repeatedly. The computer learned 39 distinctive sounds and a Chat GPT-style language system was used to translate the signals into understandable sentences. This was then used to control an avatar with a voice personalised to sound like Ann’s voice before the injury, based on a recording of her speaking at her wedding.

The technology was not perfect, translating words incorrectly 28% of the time in a test run involving more than 500 phrases, and it generated brain-to-text at a rate of 78 words a minute, compared with the 110–150 words typically spoken in natural conversation. However, scientists said the latest advances in accuracy and speed suggest the technology is now at a point of being practically useful for patients. A crucial next step is to create a wireless form that could be put beneath the skull (颅骨).