EEG Characteristic Investigation of the Sixth-Finger Motor Imagery

Supernumerary Robotic Limbs (SRL) are body augmentation robotic devices by adding extra limbs or fingers to the human body different from the traditional wearable robotic devices such as prosthesis and exoskeleton. We proposed a novel MI-based BCI paradigm based on the sixth-finger which imagines controlling the extra fingermovements. The goal of this work was to investigate the EEG characteristics and the application potential of MI-based BCI systems based on the new imagination paradigm (sixth-finger MI). 14 subjects participated in the experiment involving the sixth-finger MI tasks and rest state. Event-related spectral perturbation (ERSP) was adopted to analyze EEG spatial and time-frequency features. Common spatial patterns (CSP) were used for feature extraction and classification was implemented by support vector machine (SVM). ERD (event-related desynchronization) was found in the supplementary motor area (SMA) and primary motor area (M1) with a faint contralateral dominance. Unlike traditional human hand MI, ERD was also found in frontal lobe. The highest accuracy of 80% and mean accuracy of 70%. This work provided a novel paradigm for MI-based MI system, widened the control bandwidth of the BCI system. In addition, we discussed the application potential of the sixth-finger MI.