“A man paralyzed from the neck down due to a spinal cord injury he sustained in 2007 has shown he can communicate his thoughts, thanks to a brain implant system that translates his imagined handwriting into actual text.
The device – part of a longstanding research collaboration called BrainGate – is a brain-computer interface (BCI), that uses artificial intelligence (AI) to interpret signals of neural activity generated during handwriting.
In this case, the man – called T5 in the study, and who was 65 years of age at the time of the research – wasn’t doing any actual writing, as his hand, along with all his limbs, had been paralyzed for several years.
But during the experiment, reported in Nature earlier in the year, the man concentrated as if he were writing – effectively, thinking about making the letters with an imaginary pen and paper.
As he did this, electrodes implanted in his motor cortex recorded signals of his brain activity, which were then interpreted by algorithms running on an external computer, decoding T5’s imaginary pen trajectories, which mentally traced the 26 letters of the alphabet and some basic punctuation marks.
“This new system uses both the rich neural activity recorded by intracortical electrodes and the power of language models that, when applied to the neurally decoded letters, can create rapid and accurate text,” says first author of the study Frank Willett, a neural prosthetics researcher from Stanford University.
Similar systems developed as part of the BrainGate have been transcribing neural activity into text for several years, but many previous interfaces have focused on different cerebral metaphors for denoting which characters to write – such as point-and-click typing with a computer cursor controlled by the mind.
It wasn’t known, however, how well the neural representations of handwriting – a more rapid and dexterous motor skill – might be retained in the brain, nor how well they might be leveraged to communicate with a brain-computer interface, or BCI.
Here, T5 showed just how much promise a virtual handwriting system could offer for people who have lost virtually all independent physical movement.
In tests, the man was able to achieve writing speeds of 90 characters per minute (about 18 words per minute), with approximately 94 percent accuracy (and up to 99 percent accuracy with autocorrect enabled).
Not only is that rate significantly faster than previous BCI experiments (using things like virtual keyboards), but it’s almost on par with the typing speed of smartphone users in the man’s age group – which is about 115 characters or 23 words per minute, the researchers say….”