Brain modulation by event-related desynchronization (ERD) guided neurofeedback: toward a new therapy in acute stroke

Motor imagery (MI) therapy is suggested to assist motor (re)learning during stroke rehabilitation. During MI training, part of motor neurons is being recruited similar to motor execution. Repetitive recruitment of motor neurons through mental training leads to enhancement and/or restoration of connections among neurons (brain’s plasticity). Clinical gain in restoring motor dysfunction by MI therapy was proven in various chronic stroke patients, but not yet in patients at acute-or-subacute phase, which is considered as a prime period to determine the final outcome after stroke. In acute stroke patients, motor imagery has been shown to be less strong, so it is important to improve MI performance. One way to do that is to incorporate feedback about the MI effort in an EEG based BCI training system. In this study, we investigated how to improve imagery. For this, we developed an EEG-ERD based MI-neurofeedback system, in which the feedback information showed live MI performance. However, the result from our pilot study showed limited effect of neurofeedback on improving MI-and-physical performance. As such this may be a “warning”, when proceeding to test the method in patients. “Shall we discard the motor imagery training?” The answer is no. Although motor imagery training may not play a leading role in motor (re)learning, its supportive role is undeniable. We suggest using the combination of motor- and mental practice as the most promising approach to assist recovery from stroke. In the future, the next logical step is to find the optimal ratio between motor and mental training that would optimize motor acquisition in healthy subjects. Once that ratio of mental/motor practice is found, a pilot study in stroke patients can be started.