Electrocorticography (ECoG) has been demonstrated as a promising neural signal source for developing brain-machine interfaces (BMIs). However, many concerns about the disadvantages brought by large craniotomy for implanting the ECoG grid limit the clinical translation of ECoG-based BMIs. In this study, we collected clinical ECoG signals from the sensorimotor cortex of three epileptic participants when they performed hand gestures. The ECoG power spectrum in hybrid frequency bands was extracted to build a synchronous real-time BMI system. High decoding accuracy of the three gestures was achieved in both offline analysis (85.7%, 84.5%, and 69.7%) and online tests (80% and 82%, tested on two participants only). We found that the decoding performance was maintained even with a subset of channels selected by a greedy algorithm. More importantly, these selected channels were mostly distributed along the central sulcus and clustered in the area of 3 interelectrode squares. Our findings of the reduced and clustered distribution of ECoG channels further supported the feasibility of clinically implementing the ECoG-based BMI system for the control of hand gestures.

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Brain machine interfaces (BMIs) have emerged as a technology to restore lost functionality in motor impaired patients. Most BMI systems employed neural signals from contralateral hemisphere. But many studies have also demonstrated the possibility to control hand movement using signals from ipsilateral one. However, the relationship of neural signals in sensorimotor cortex between contralateral and ipsilateral hand movement control is still unclear. In this study, the electrocorticographic signals (ECoG) of sensorimotor cortex were analyzed in two epilepsy participants when they performed a visual guided rock-scissors-paper task by using contralateral and ipsilateral hand respectively. Although typical beta suppression followed increased gamma were observed during the movements of each individual hands, the stronger responses were found in two participants when their contralateral hands were used during the task. We further extracted the power spectrum of high gamma frequency band (70-135Hz) of ECoG signals as neural features to decode the hand movements. The results showed that the classification accuracy of contralateral decoding and ipsilateral decoding were 81% and 78% for participator one (P1) and 84% and 77% for participator two (P2). The accuracy of ipsilateral decoding was only slightly lower than that of contralateral one. The hand movement information contained in ipsilateral sensorimotor cortex suggested that the ipsilateral hemisphere might be also involved in neural modulation as well as contralateral hemisphere did when performing unimanual movement, which would expand the clinical application of BMIs.

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