Visual Training Improves Motor Imagery Ability for Rehabilitation

Motor imagery (MI) is the most favorable brain action exploited in motor deficit rehabilitation. The hemodynamic response (HR) signal is usually weak, which can be enhanced with specific methods. In this research, the improvement in the HR was examined while the participants performed the MI task of right-hand movement. Brain signals, i.e., concentration changes in oxyhemoglobin ($\Delta\text{HbO}$) from the left sensorimotor cortex, were attained through functional near-infrared spectroscopy. The experiment was executed in 2 sessions. The first session consisted of the performance of the MI task without visual training. Whereas in the last session, the MI task was performed but with the visual training: A videotape was played on the computer screen that presented a person moving his right hand, repeatedly; the purpose was to help in enhancing the imaginations and, therefore, improving the HR. The t-values between the measured HR and the designed hemodynamics response function were calculated to check certain channels' activeness. Later, the trials of active channels were averaged to obtain mean $\Delta\text{HbO}$. MI task with visual training showed elevated activation in $\Delta\text{HbO}$. Furthermore, linear discriminant analysis was utilized to classify signals by taking the mean and maximum of HR resulting in mean classification accuracy of 65% and 80% for MI tasks with- and without visual training. These results reflected an enhancement in MI ability through visual training, which will help patients' rehabilitation and BCI applications.