A New Brain Implant Can Convert Neural Signals to Speech, But Can It Help People With Aphasia?

You probably already heard about the new brain implant that can convert brain signals to almost regular speech via the use of a speech synthesizer. The recent study made a big splash in the media and many in the aphasia community wanted to know more. We reached out to the leading scientists who developed the brain implant to ask them if and how it can help people with aphasia.

How does it work?

Researchers implanted a chip that reads neural signals from an area of the brain that controls the movements of the mouth and the vocal tract – the tongue, lips, and the vocal cords. Those movements are the ones that result in speech. The technique used motor signals sent to the vocal tract muscles to interpret what the person wants to say. The implant technology then directed a speech synthesizer – a virtual vocal tract – to say the intended words and sentences.

Would it work for a person who has aphasia?

The problem to use this method in people with aphasia, according to Edward Chang, the leading scientists of this study, is that their method so far relies on the speech areas to be intact. In people with aphasia, speech areas are damaged due to stroke or other type of brain injury.

This new technology is mostly relevant to people with “lower-level paralysis like ALS (amyotrophic lateral sclerosis) or locked-in syndrome since it primarily relies on information from the part of the brain that controls movement,” adds Frank Guenther, a speech and language scientists at Boston University, who was not involved in the study.

What is the silver lining?

While not immediately applicable to patients with aphasia, Dr. Chang thinks that the current success at interpreting brain signals and converting them to speech gives hope that in the future such devices can decode signals from more complex language areas. Dr. Guenther agrees that the mathematical techniques used in the study may eventually be useful for decoding information from higher brain areas and possibly bypassing a damaged brain area in the process. If that works, such a device could overcome deficits related to non-motor aspects of language such as the inability to construct a sentence, or to find the right word, or to understand what another person is saying. In other words, those deficits that persons with aphasia experience.

Dr. Chang cautiously adds though that “there are rather fundamental questions we still have about the function of language centers of the brain” before this becomes reality.

And what about the implant – is it ready for use at home?

We wanted to know also if the technology itself, the chip, is ready to be implanted safely and durably in a person’s brain. Can a person get the implant, go home and go about their daily life? Turns out not quite yet but the team of Dr. Chang is working on making the device fully implantable and safe, and hoping to make it available to patients in the near future.

The take-home message

The most promising current options, at least for the moment, remain therapies that leverage undamaged parts of the brain to take over lost functionality.

 

Contributors:
Edward Chang is the leading researchers of the study. He is a Professor of Neurological Surgery at University of California San Francisco
Frank Guenther is a Professor of Speech, Language & Hearing Sciences at Boston University 

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