Modulating and restoring inter-muscular coordination in stroke patients using two-dimensional myoelectric computer interface: a cross-sectional and longitudinal study

Abstract Objective. Traditional training focuses on improving the motor function level of the limbs or joint levels, while inter-muscular coordination plays an important role in fine motor control and is often overlooked. The purpose of this study was to investigate the changes in inter-muscular coordination induced by the myoelectric-controlled interface (MCI) and the therapeutic effects of MCI-based inter-muscular coordination training on stroke patients. Approach . Eleven stroke patients, twenty young subjects and thirteen age-matched subjects were recruited to determine the dimensionality effect of MCI on inter-muscular coordination in the evaluation test. In addition, a stroke patient participated in a 20-day training session to test the therapeutic effects as a case study analysis in the training test. In these two tests, all subjects performed tracking tasks by flexing/extending their elbows according to the biofeedback from one-dimensional and two-dimensional (2D) MCI. Meanwhile, the electromyography and functional near infrared spectroscopy signals were recorded simultaneously to reflect the muscle and cortical activations. Main results . In all groups, as the MCI dimensionality increased, the antagonist activation decreased significantly, while the involvement in prefrontal cortex and primary motor cortex increased significantly. A significant reduction in muscle activation and an increase in cortical activation were found in the stroke patient, which might be due to a progressive normalization of patient after the training. Significance . These findings suggested that 2D MCI could be an effective tool to directly modulate inter-muscular coordination for stroke patients. Inter-muscular coordination training may restore the ability to coordinate agonist-antagonist muscle of stroke patient and this improvement may be accompanied by cortical reorganization.