A research team at UC Davis and UC Davis Health has shown that brain-computer interfaces (BCIs) designed to translate brain signals into speech can also be used to control a computer cursor. This achievement could help people with paralysis gain more independence.
The findings, published in the Journal of Neuroengineering, were supported by the National Science Foundation and the National Institutes of Health. The study demonstrates that BCIs can be developed to offer a range of functions beyond speech for people with paralysis.
“Future steps in multimodal BCIs could include gesture decoding for all sorts of different things, enriching the types of interactions someone with paralysis can have with their environment beyond speech,” said Tyler Singer-Clark, a biomedical engineering Ph.D. student and first author on the paper.
Singer-Clark is part of the UC Davis Neuroprosthetics Lab, which is co-directed by neuroscientist Sergey Stavisky and neurosurgeon David Brandman. The lab previously developed a highly accurate speech BCI, and Singer-Clark’s project builds on that work.
The team’s BCI is implanted in the speech motor cortex and interprets electrical activity from thoughts, converting it into words displayed on a computer. During their research, they noticed that the same brain region used for speech might also support cursor control, which is usually linked to a different area of the brain.
Singer-Clark then developed cursor control software for the speech BCI. He drew on previous research about cursor control using other brain regions and adapted the existing speech BCI code for this purpose.
“We didn’t have to reinvent the pre-processing of the neural data,” he said. “For cursor control, it’s actually the same pre-processing steps the speech BCI uses to get the neural features that are going to be useful for decoding the intention of the participant.”
Singer-Clark worked with a participant from the original speech BCI research, who is part of the BrainGate clinical trial and lives with amyotrophic lateral sclerosis (ALS), a disease that causes loss of movement. The participant watched a cursor move on a screen while Singer-Clark observed his brain activity. By mapping specific neural signals to cursor movements, they enabled the participant to control the cursor through thought.
After enabling the software for his implanted BCI, the participant adapted to using the cursor in less than 40 seconds. He was able to move the cursor, click on apps, and open links on his computer using only his thoughts.
Singer-Clark explained that the BCI does not translate abstract thoughts into movement but relies on a sense of intuition. “That’s his word, intuition,” Singer-Clark said. “I’ll say, ‘What motor imagery are you using?’ And he says, ‘Intuition.’”
David Brandman, co-director of the Neuroprosthetics Lab, commented on the significance of this work: “Singer-Clark’s work is incredibly important for the field. His work has not only empowered our BrainGate2 participant to use a computer cursor with his thoughts but has also led the way for multiple companies in this space to design their clinical trials.”
Singer-Clark emphasized that this project proves complex BCIs are possible and that body movements may be represented in multiple areas of the motor cortex. He also highlighted the personal impact: “There’s a man with ALS who can control his computer independently without someone else helping him for hours and hours every day. It’s like this great event, and we might not have tried if we didn’t have that prior research encouraging us to do that.”
The team at UC Davis continues to work toward technologies that allow people with paralysis to achieve greater autonomy.
