Lower limb motor intention: ERD time-course analysis in stroke and healthy subjects
A brain computer interface (BCI) aimed at motor recovery identifies features of the electroencephalography (EEG) signal that are evidenced when the patient performs a motor intention (MI) task, which consists in executing a residual movement with the affected limb. MI is observed as a decrease relative to rest in the power of the EEG sensorimotor rhythms, which is known as Event-related Synchronization (ERD). This paper characterized ERD time-course in healthy subjects that simulated lower limb MI and compared it with stroke patients MI; in order to explore differences and similarities between them, and analyze if simulated MI could be used in the preliminary evaluation of a BCI intended for lower limb motor recovery. EEG signals from six healthy subjects and four patients with stroke motor sequelae were processed. In total, 180 motor attempts were obtained for healthy subjects' right and left foot respectively; and 120 for patients' affected foot. ERD time-course was calculated and studied. The results showed that simulated MI ERD evidenced similarities in amplitude and temporal occurrence compared to the patients’ affected foot MI ERD. It is concluded that it would be possible to use simulated MI to evaluate a BCI with motor recovery purposes before being transferred for clinical use.