title: Brain-machine interface to control a prosthetic arm with monkey ECoGs during periodic movements.
abstract: Brain-machine interfaces (BMIs) are promising technologies for rehabilitation of upper limb functions in patients with severe paralysis. We previously developed a BMI prosthetic arm for a monkey implanted with electrocorticography (ECoG) electrodes, and trained it in a reaching task. The stability of the BMI prevented incorrect movements due to misclassification of ECoG patterns. As a trade-off for the stability, however, the latency (the time gap between the monkey's actual motion and the prosthetic arm movement) was about 200 ms. Therefore, in this study, we aimed to improve the response time of the BMI prosthetic arm. We focused on the generation of a trigger event by decoding muscle activity in order to predict integrated electromyograms (iEMGs) from the ECoGs. We verified the achievability of our method by conducting a performance test of the proposed method with actual achieved iEMGs instead of predicted iEMGs. Our results confirmed that the proposed method with predicted iEMGs eliminated the time delay. In addition, we found that motor intention is better reflected by muscle activity estimated from brain activity rather than actual muscle activity. Therefore, we propose that using predicted iEMGs to guide prosthetic arm movement results in minimal delay and excellent performance.
authors.affiliation: Brain Science Inspired Life Support Research Center, The University of Electro-Communications Chofu, Japan.
authors.forename: Soichiro
authors.initials: S
authors.lastname: Morishita
authors.affiliation: Department of Mechanical Engineering and Intelligent Systems, The University of Electro-Communications Chofu, Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Sato
authors.affiliation: Division of Behavioral Development, Department of Developmental Physiology, National Institute for Physiological Sciences Okazaki, Japan.
authors.forename: Hidenori
authors.initials: H
authors.lastname: Watanabe
authors.affiliation: Division of Behavioral Development, Department of Developmental Physiology, National Institute for Physiological Sciences Okazaki, Japan ; Department of Physiological Sciences, School of Life Science, The Graduate University for Advanced Studies (SOKENDAI) Hayama, Japan ; PRESTO, Japan Science and Technology Agency Kawaguchi, Japan.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Nishimura
authors.affiliation: Division of Behavioral Development, Department of Developmental Physiology, National Institute for Physiological Sciences Okazaki, Japan ; Department of Physiological Sciences, School of Life Science, The Graduate University for Advanced Studies (SOKENDAI) Hayama, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Isa
authors.affiliation: Division of Systems Research, Department of Systems Design, Faculty of Engineering, The Yokohama National University Yokohama, Japan.
authors.forename: Ryu
authors.initials: R
authors.lastname: Kato
authors.affiliation: Integrative Brain Imaging Center, National Center of Neurology and Psychiatry Kodaira, Japan.
authors.forename: Tatsuhiro
authors.initials: T
authors.lastname: Nakamura
authors.affiliation: Department of Mechanical Engineering and Intelligent Systems, The University of Electro-Communications Chofu, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yokoi
keywords: brain-machine interfaces; electrocorticography; electromyography; prosthetic arm; reaching task