Enhanced motor imagery based brain-computer interface via unilateral wrist vibrotactile stimulation

It is investigated that unilateral sensory stimulation during the motor imagery period might enhance the sensory motor interaction reflected from enhanced sensorimotor rhythm, and the outcomes might be helpful for those with difficulty in producing discriminative rhythmic pattern for successful BCI practice such as hemiplegic stroke patients, amputees and widely existed 'BCI-illiteracy' users. In the present study, subjects were required to perform left and right motor imagery tasks under three different conditions, with nonstimulation in session one, only left stimulation in session two, and only right stimulation in session three. The experiment showed that subject's mental intentions can be still decoded under the sensory stimulation condition, and 4 of the 6 subjects showed a significant increase (p < 0.01) in the right stimulation condition compared to non-stimulation condition. Enhanced cortical activation as reflected from increased ERD (event related desynchronization) strength was presented in the sensory stimulation condition among majority of the subjects, whilst some subjects showed that the ERD strength was stronger when stimulation, motor imagery were on the same side compared to the different side. It is suggested that the proposed experimental paradigm can be used as a good intervention for those 'BCI-illiteracy' people and enhance the sensory motor interaction process for rehabilitation of those with motor impairment.