Neuroprosthesis – allowing paralyzed people to communicate

Saakshi Bangera, DY Patil School of Biotechnology and Bioinformatics

Paraplegic people who have lost the ability to speak communicate using devices that use motor movements to spell words out one letter at a time. Some rely on a device that lets them control a computer cursor with thoughts. Scientists are working on various techniques to restore the ability of paralyzed people to communicate. Such technology can help improve the quality of life of patients. A neuroscientific team of the University of California has developed a system to allow a paralyzed person to communicate. The system reads the brain activity of the paralyzed person and converts it into a readable form. It decodes words directly from the cortical cerebral activity and assists in communication. 

This technological ability derives from an experimental implant device that deciphers brain signals that once controlled the person’s vocal tract. The team of neuroscientists implanted a subdural, high-density, multielectrode array over the sensorimotor cortex of the person. 48 sessions later, the team recorded 22 hours of brain activity while the participant speaks individual words from a set of 50. The patterns of cortical activity were recorded and added to deep-learning algorithms. The algorithms detect and classify words from the recorded patterns and create computational models. These computational models along with a natural-language model produce next-word probabilities to decode the full sentence as the person says them. The device decodes the brain’s electrical impulses to display words on a computer screen. 

The team of doctors surgically inserted a high-density electrode array into the sensorimotor cortex (speech motor cortex) of the paralyzed man in this study referred to as BRAVO1. The device was linked to a computer through an interface in his head. 

About BRAVO1

The name BRAVO1 honors the first patient of the study called BRAVO which is basically a Brain-Computer Interface Restoration of Arm and Voice. BRAVO1 is aged around 40, was paralyzed 15 years ago due to a stroke, and has been unable to speak since then. 

Results

At an approximate rate of 15% words per minute, the team of scientists decoded sentences from the person’s cortical activity. 98% of the participant’s attempts were detected with 47% accuracy. The team recorded the participant’s brain activity when he attempted to speak a list of 50 common words. BRAVO1 was asked to recite short sentences while the device decoded the words and displayed them on the screen. The team conducted a short question-and-answer session, in which they asked BRAVO1, “How are you?”. To this, the screen displayed, “I am extremely excellent”.

Significance

According to the researchers, this was the first time that a technological system has successfully translated the brain activity of a paraplegic person into full phrases. The technology has a tremendous potential to reinstate communication by tapping into the brain’s native speech system. However, this technology has certain flaws such as decoding an average of 15 words per minute. The rate is slow as compared to the normal speed of speech, which is 100-200 words per minute. The team aims to enhance the system and improve the accuracy rate. The technology has a solid potential to completely restore communication for people who’ve lost their ability to speak. The team also aims to make sure that the devices allow the separation of public and private thoughts.  

Also read: Nanoparticles to treat a common type of cancer- neuroblastoma

References

1. Moses, D. A., Metzger, S. L., Liu, J. R., Anumanchipalli, G. K., Makin, J. G., Sun, P. F., Chartier, J., Dougherty, M. E., Liu, P. M., Abrams, G. M., Tu-Chan, A., Ganguly, K., & Chang, E. F. (2021). Neuroprosthesis for decoding speech in a paralyzed person with anarthria. New England Journal of Medicine, 385(3), 217–227. https://doi.org/10.1056/NEJMoa2027540
2. Experimental brain implant lets man with paralysis turn his thoughts into words. (n.d.). NPR.Org. Retrieved August 3, 2021, from https://www.npr.org/sections/health-shots/2021/07/14/1016028911/experimental-brain-implant-lets-man-with-paralysis-turn-his-thoughts-into-words
3. Krishnan, A. U. (2021, August 1). Medical Researchers tests “Brain Implant System” helping paralyzed man to speak. TechStory. https://techstory.in/medical-researchers-tests-brain-implant-system-helping-paralyzed-man-to-speak/ 

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About the author

The author is currently pursuing MSc in Biotechnology from DY Patil School of Biotechnology and Bioinformatics. She believes that she doesn’t have a specific area of interest yet. She wishes to explore toxicology and food biotechnology. She’s quite passionate about Biotechnology and aims to grab every opportunity she comes across.

Previous publications

1. https://bioxone.in/news/indianews/first-ever-case-of-zika-virus-in-maharashtra/ 
2. https://bioxone.in/news/worldnews/early-animals-probably-survived-the-neoproterozoic-era/ 
3. https://bioxone.in/news/worldnews/xylans-an-undervalued-biorefinery-gem/