| Outline of Annual Research Achievements |
The objectives of this research are to develop: (1) a brain-computer interface (BCI) system that can detect hand opening / closing movements using non-invasive cortical (brain) signals from human participants during motor imagery tasks, and (2) a neuroprosthetic technology that can activate the upper-limb muscles through functional electrical stimulation (FES). Finally, the research program aims to test the feasibility of this BCI-controlled FES neuroprosthetic and examine how it can contribute to restoration of upper-limb motor function. Based on these objectives, we have developed and implemented a BCI-controlled FES system and proposed the underlying mechanisms of recovery of upper-limb motor function that can be elicited through BCI-controlled FES. We showed that presynaptic cortical facilitation followed by postsynaptic FES (BCI-controlled FES) is required to elicit short-term corticospinal facilitation, while only postsynaptic FES (random FES) activation was ineffective. Moreover, we have been testing how FES can be used to activate different muscles and as such facilitate excitability of the central nervous system. Specifically, it was shown that long-term application of upper-limb FES can facilitate cortical excitability beyond the training period. In summary, a BCI-FES system with an accuracy of ~85% was developed, and it was shown to contribute to restoration of upper-limb motor function through facilitation of cortical and peripheral activations.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
(1) In the research related to the development of the BCI system, we have implemented and tested the BCI-FES system proved the underlying mechanisms of BCI-controlled FES for recovery of upper-limb function [1]. Specifically, motor imagery was shown to affect cortical networks [2]. Moreover, threshold-based motor imagery BCI was shown to work with an accuracy of ~85% [3], while a machine learning classifier had a comparable detection [4]. Notably, using the BCI-controlled FES system was shown as effective in facilitating corticospinal excitability more than random application of FES [3], confirming our results indicating that cortical facilitation before FES is necessary to elicit neural plasticity [5].
(2) In the research related to the development of FES technology, we have been testing how FES can activate muscles and the central nervous system. Specifically, we showed that upper-limb FES can elicit considerable and long-lasting cortical re-organization [6]. A book chapter is currently in preparation based on these findings for a textbook titled Neurorehabilitation Technology edited by Dr. Volker Dietz.
References: [1] M. Milosevic, et al., BioMedical Engineering Online, vol. 19, 81, 2020; [2] Y. Suzuki, et al., Neuroscience Letters, vol. 755, 2021; [3] Y. Suzuki, et al., To be submitted to Neuromodulation; [4] Y. Yamanouchi, et al., To be submitted to Artificial Organs; [5] N. Cao, et al., To be submitted to Brain Stimulation; [6] M. Milosevic, et al., medRxiv, 2020.
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| Strategy for Future Research Activity |
In the future, we will complete all analyses of data that was collected during experiments in Osaka and Tokyo. Moreover, we will continue preparing manuscripts for dissemination of research results in international peer-reviewed journals and work towards publishing all the research findings.
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| Causes of Carryover |
Travel implementation schedule for collaborative research at the University of Tokyo was adjusted due to restrictions related to COVID-19. Despite this, all BCI-FES experiments were conducted and completed at Osaka University. Moreover, experimental schedule at the University of Tokyo related to testing of FES technology were completed within the scheduled timelines with students belonging to the University of Tokyo. Currently, final data analysis and preparations for dissemination of research results in international journals is currently underway.
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