The current system already uses a couple of types of machine learning programs. To improve its accuracy, the Stanford team employed software that predicts what word typically comes next in a sentence. “I” is more often followed by “am” than “ham,” even though these words sound similar and could produce similar patterns in someone’s brain. 

Adding the word prediction system increased how quickly the subject could speak without mistakes.  

Language models

But newer “large” language models, like GPT-3, are capable of writing entire essays and answering questions. Connecting these to brain interfaces could enable people using the system to speak even faster, just because the system will be better at guessing what they are trying to say on the basis of partial information. “The success of large language models over the last few years makes me think that a speech prosthesis is close at hand, because maybe you don’t need such an impressive input to get speech out,” says Sabes.

Shenoy’s group is part of a consortium called BrainGate that has placed electrodes into the brains of more than a dozen volunteers. They use an implant called the Utah Array, a rigid metal square with about 100 needle-like electrodes.

Some companies, including Elon Musk’s brain interface company, Neuralink, and a startup called Paradromics, say they have developed more modern interfaces that can record from thousands—even tens of thousands—of neurons at once.

While some skeptics have asked whether measuring from more neurons at one time will make any difference, the new report suggests it will, especially if the job is to brain-read complex movements such as speech.

The Stanford scientists found that the more neurons they read from at once, the fewer errors they made in understanding what “T12” was trying to say.

“This is a big deal, because it suggests efforts by companies like Neuralink to put 1,000 electrodes into the brain will make a difference, if the task is sufficiently rich,” says Sabes, who previously worked as a senior scientist at Neuralink.