Scientists have achieved a remarkable milestone: a brain implant that decodes the words people speak internally without external movements or vocalizations. A study published in Nature Human Behaviour confirmed that brain implants can now decode internal speech—the words we speak to ourselves in our minds.
Why it matters:
This breakthrough could offer a revolutionary communication tool for people with severe disabilities, such as those with locked-in syndrome, the complete paralysis of all voluntary muscles except for the ones that control eye movements.
- It establishes the possibility of speaking, writing, and controlling devices using only thoughts.
What they did
Researchers implanted tiny electrodes in the brains of two participants with spinal cord injuries. The electrodes were placed in a brain region called the supramarginal gyrus, an area involved in internal speech and deciding if words rhyme.
- The participants were asked to imagine speaking six words (battlefield, cowboy, python, spoon, swimming, telephone) and two meaningless pseudowords (nifzig and bindip).
- The brain-computer interface (BCI) analyzed the brain signals and successfully decoded the words with 79% accuracy for one participant, while the other had a lower accuracy of 23%.
- The findings suggest individual differences in brain activity during internal speech.
Three challenges
- Determine the optimal brain regions to place BCIs.
- Test whether the BCI can distinguish between letters of the alphabet, potentially leading to an internal speech speller for communication.
- Since this study involved participants who could still speak, it is unknown if these findings would apply to those with permanent speech loss.
The bottom line
The research paves the way for using internal speech to communicate and give people greater independence.
