Investigation of optimal visual cue for training of motor-imagery response

We are developing Digital Mirror Box (DMB), a brain machine interface (BMI)based rehabilitation system for stroke patients with hand paralysis. Aiming to train the motor-command generation from the affected hemisphere, DMB uses an event related desynchronization (ERD) derived from motor imagery as an operating signal of the BMI feedback. In order to assist the patients to perform motor imagery, the current DMB system presents a movie of hand motion, in which a hand-grasping motion picture is presented immediately after a still image of the fixation point. However, there remains a possibility that the detected ERD is influenced by an attentional switching from still to motion picture, not by action observation or motor imagery per se. We therefore modified the movie to contain a still image of a resting hand between fixation cue and hand motion picture. We could successfully differentiate the μ band suppression of the attentional switching from those derived from motor imagery.