Effect of real-time cortical feedback in motor imagery-based mental practice training

Abstract

Background: Mental practice using motor imagery of limb movement may facilitate motor recovery in persons who have experienced cerebrovascular accident (CVA). However, the lack of a feedback mechanism that can monitor the quality of the motor imagery affects patients' engagement and motivation to participate in the mental practice training program.

Objective: This study investigates the effect of novel real-time motor imagery-associated cortical activity feedback on motor imagery-based mental practice training.

Methods: Ten healthy volunteers were randomly assigned into intervention and control groups. Both groups participated in a five-visit motor imagery-based mental practice training program managed over a period of two months. The intervention group received mental practice training with real-time feedback of movement-associated cortical activity-beta band (16-28 Hz) event-related desynchronization (ERD) in electroencephalography (EEG), using a novel custom-made brain-computer interface (BCI) system. The control group received the mental practice training program without EEG cortical feedback. Motor excitability was assessed by measuring the frequency power magnitude of the EEG rhythmic activity associated with physical execution of wrist extension before and after the motor imagery-based mental practice training.

Results: The EEG frequency power magnitude associated with the physical execution of wrist extension was significantly lower (i.e. more desynchronized) after the mental practice training in the intervention group that received real-time cortical feedback (P < 0.05), whereas no significant difference in EEG frequency power magnitude associated with the physical execution of wrist extension was observed before and after mental practice training in the control group who did not receive feedback.

Conclusions: The mental practice training program with motor imagery-associated cortical feedback facilitated motor excitability during the production of voluntary motor control. Motor imagery-based mental practice training with movement-associated cortical activity feedback may provide an effective strategy to facilitate motor recovery in brain injury patients, particularly during the early rehabilitation stage when full participation in physical and occupational therapy programs may not be possible due to excessive motor weakness.

Keywords: Motor imagery; brain-computer interface (BCI); electroencephalography (EEG); event-related desynchronization (ERD); mental practice; motor control.