PT  - JOURNAL ARTICLE
AU  - Hikaru Yokoyama
AU  - Naotsugu Kaneko
AU  - Tetsuya Ogawa
AU  - Noritaka Kawashima
AU  - Katsumi Watanabe
AU  - Kimitaka Nakazawa
TI  - Cortical control of locomotor muscle activity through muscle synergies in humans: a neural decoding study
AID  - 10.1101/413567
DP  - 2018 Jan 01
TA  - bioRxiv
PG  - 413567
4099  - http://biorxiv.org/content/early/2018/09/11/413567.short
4100  - http://biorxiv.org/content/early/2018/09/11/413567.full
AB  - Walking movements are orchestrated by the activation of a large number of muscles. The control of numerous muscles during walking is believed to be simplified by flexible activation of groups of muscles called muscle synergies. Although significant corticomuscular connectivity during walking has been reported, the level at which the cortex controls locomotor muscle activity (i.e., muscle synergy or individual muscle level) remains unclear. Here, we examined cortical involvement in muscle control during walking by brain decoding of the activation of muscle synergies and individual muscles from electroencephalographic (EEG) signals using linear decoder models. First, we demonstrated that activation of locomotor muscle synergies was decoded from slow cortical waves with significant accuracy. In addition, we found that decoding accuracy for muscle synergy activation was greater than that for individual muscle activation and that decoding of individual muscle activation was based on muscle synergy-related cortical information. Taken together, these results provide indirect evidence that the cerebral cortex hierarchically controls multiple muscles through a few muscle synergies during walking. Our findings extend the current understanding of the role of the cortex in muscular control during walking and could accelerate the development of effective brain-machine interfaces for people with locomotor disabilities.