Enhancement Effect of ERD Activation Based on Multi-limb Cooperation Motor Imagery Compared with Inherent Limbs

Supernumerary robotic limbs (SRLs) show great potential in enhancing human motor functions and the brain-computer interface based on motor imagery (MI-BCI) has achieved the control of SRLs initially. However, how to establish natural, intuitive and various control instructions of SRLs is still an essential problem. In this work, we proposed two new MI paradigms of multi-limb cooperative movement consisting of SRLs and inherent limbs, including catching-ball and twisting-cap, explored the EEG response characteristics and proved the separability between multi-limb cooperative MI (ML-MI) and inherent-limb MI (IL-MI). Fourteen subjects were recruited for this experiment involving five mental tasks. The comparative analysis results of brain topology maps and time-frequency maps showed that ML-MI induced more obvious event-related desynchro-nization (ERD) phenomenon than IL-MI, especially in the catching-ball task. The 2-class classification results confirmed the feasibility of new paradigms for SRLs control and the separability between ML-MI and IL-MI. The proposal of new MI paradigms of multi-limb cooperative movement may promote the development of natural interaction and cooperation between humans and SRLs, and expand the instructions of MI control.