Efforts to restore speech to people silenced by brain injuries and diseases have taken a significant step forward with the publication of two new papers in the journal Nature.
In the work, two multidisciplinary teams demonstrated new records of speed and accuracy for state-of-the-art, AI-assisted brain-computer interface (BCI) systems. The advances point the way to granting people who can no longer speak the ability to communicate at near conversation-level pace and even show how that text can be retranslated into speech using computer programs that mimic the patient’s voice. One group developed a digital avatar that a paralyzed patient used to communicate with accurate facial gestures.
Paper
A high-performance speech neuroprosthesis
Abstract
Speech brain–computer interfaces (BCIs) have the potential to restore rapid communication to people with paralysis by decoding neural activity evoked by attempted speech into text1,2 or sound3,4. Early demonstrations, although promising, have not yet achieved accuracies sufficiently high for communication of unconstrained sentences from a large vocabulary1,2,3,4,5,6,7. Here we demonstrate a speech-to-text BCI that records spiking activity from intracortical microelectrode arrays. Enabled by these high-resolution recordings, our study participant—who can no longer speak intelligibly owing to amyotrophic lateral sclerosis—achieved a 9.1% word error rate on a 50-word vocabulary (2.7 times fewer errors than the previous state-of-the-art speech BCI2) and a 23.8% word error rate on a 125,000-word vocabulary (the first successful demonstration, to our knowledge, of large-vocabulary decoding). Our participant’s attempted speech was decoded at 62 words per minute, which is 3.4 times as fast as the previous record8 and begins to approach the speed of natural conversation (160 words per minute9). Finally, we highlight two aspects of the neural code for speech that are encouraging for speech BCIs: spatially intermixed tuning to speech articulators that makes accurate decoding possible from only a small region of cortex, and a detailed articulatory representation of phonemes that persists years after paralysis. These results show a feasible path forward for restoring rapid communication to people with paralysis who can no longer speak.