Noninvasive brain-computer interface enables communication after brainstem stroke

Abstract

Brain-computer interfaces (BCIs) provide communication that is independent of muscle control, and can be especially important for individuals with severe neuromuscular disease who cannot use standard communication pathways or other assistive technology. It has previously been shown that people with amyotrophic lateral sclerosis (ALS) can successfully use BCI after all other means of independent communication have failed. The BCI literature has asserted that brainstem stroke survivors can also benefit from BCI use. This study used a P300-based event-related potential spelling system. This case study demonstrates that an individual locked-in owing to brainstem stroke was able to use a noninvasive BCI to communicate volitional messages. Over a period of 13 months, the participant was able to successfully operate the system during 40 of 62 recording sessions. He was able to accurately spell words provided by the experimenter and to initiate dialogues with his family. The results broadly suggest that, regardless of the precipitating event, BCI use may be of benefit to those with locked-in syndrome.

Fig. 1. Displays used for spelling

(A) The 6 × 6 display used to select letters. Entire rows and columns flashed and the participant focused on the desired letter. Rows and columns flash at random. (B) For the four-choice display, the four letters flash and the participant attends to the letter corresponding to the answer to the question: “Y” (yes), “N” (no), “P” (pass), or “E” (end). (C) Seven-choice toggle speller [see (D) for toggle description]. (D) The 3 × 6 toggle display. The items selected are labeled with yellow circles. The blue arrows indicate the order of selection. Items selected by the BCI are located in the top left of the gray output bar. The left panel shows the first display of items. In this example, the word to be spelled is HAPPY. “H” is selected and placed in the output bar, and then “A” is selected. After the selection of “A,” it was necessary to switch to the second display by selecting “Next.” The red lines indicate that selecting “Next” spawns the second display. The participant could then select “PPY.” Selecting “Back” (dashed blue line) returned to the initial display.