Simultaneous Observation and Imagery of Hand Movement Enhance Event-Related Desynchronization of Stroke Patients

During voluntary movement, motor imagery (MI), or action observation (AO), the short-lasting attenuation or blocking of rhythms within alpha or beta band of electroencephalogram (EEG) called event-related desynchronization (ERD) is observed over the central area. Some studies showed that with the increase of the ERD during MI, impaired motor function after stroke was improved. Recently, it has been reported that the ERD of healthy subjects during combined AO and MI (AO+MI) was stronger than that during either MI or AO individually. However, it is unclear how AO+MI affects stroke patients in terms of the ERD. To investigate this, in this paper, EEG signals during the three tasks, gazing at a still picture (termed Gaze), MI, and AO+MI, of stroke patients and healthy subjects were analyzed. Statistical analyses showed that the ERD of AO+MI was stronger than that of Gaze or MI. This implies that AO+MI may be more effective approach to recover the motor function in terms of neurorehabilitation.