Brain-Computer Interface Channel-Selection Strategy Based on Analysis of Event-Related Desynchronization Topography in Stroke Patients

Figure 1

Each trial started with a fixation cross displayed in the center of the screen, which lasted for the whole trial from the first to seventh second. The cue for motor attempt appeared from the fourth to fifth second as a red arrow pointing to the right or left side specifying the task to be performed. When no arrow appeared, it was the blank control, during which the subject need not do anything but stare at the cross center. Patients were required to stop the task when the cue disappeared at the end of the seventh second, and only the fixation cross was shown till the end of the trial. To avoid adaptation to the timing, cues were presented in randomized sequence with randomized intervals between 5 seconds and 6 seconds between each trial.