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

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.