Can Corticomuscular Coupling be Useful in Designing Hybrid-Brain Robot Interfaces Towards Hand Functional Recovery?

Corticomuscular coupling is so far widely explored only for the assessment of motor recovery. However, the possibility of using it for driving hybrid Brain-robot interfaces (h-BRI) is much ignored. Being an important factor for in re-establishing the connection between brain and muscle, corticomuscular coupling might play an important role in providing meaningful neurofeedback of the therapeutic task performance leading to faster recovery. This paper reports a 5-week-long clinical study on 4 chronic stroke patients where we have used correlation of band-limited power time-courses (CBPT), a measure of corticomuscular coupling, as a feature for providing multimodal neurofeedback for hand exoskeleton based therapy. The primary outcome is measured using the standard motor recovery measures of action research arm test (ARAT) and grip-strength (GS). As a secondary measure of recovery, the resting state MEG was also recorded on a weekly basis. The usability of the system was also assessed using the visual-analog-scale measurements of the patients' motivation and fatigue. Results show that the h-BRI performance increased significantly (p-value <; 0.05) from the average 58.16±7.81% from the beginning to the 77.17±3.65% at the end session. A positive change in the ARAT (+23.75) and GS (+9.83 kg) scores was also observed as compared to the baseline. Both of these changes were beyond the minimal clinically important difference (MCID) limit. Overall, the study shows that corticomuscular coupling can be used to design a high-performing BRI which also has the potential of being clinically effective.