The training regime consisted of 14 MI sessions over a time course of 4 weeks. Three chronic stroke patients practiced MI neurofeedback using kinaesthetic imagination of a power grip of either the affected or the unaffected hand. Neurofeedback was based on features extracted from the 8-30 Hz frequency range. MI training was conducted at the patients’ home using a fully mobile 24-channel EEG system. Before and after the training, motor functions were assessed using a modified version of the Fugl-Meyer Assessment (FMA) and the modified Motor Assessment Scale (MAS). Moreover, pre- and post-training 96-channel EEG recordings were performed for MI and movement execution (ME) of the power grip task that was used for the MI neurofeedback training. Event-related desynchronization (ERD) in the 8–30 Hz frequency range was extracted offline for a region of interest analysis. Analysis focused on contra- and ipsilateral ERD and on the lateralization of ERD, defined as the difference between contralateral and ipsilateral ERD.
All patients remained motivated throughout the training and completed the training regime. During MI and ME with the unaffected hand, patients showed stronger contralateral than ipsilateral activity in both the pre- and the post-training sessions. For the affected hand, MI and ME were however associated with stronger ipsilateral than contralateral activity. Changes were observed over the course of training, that, on a descriptive level, suggest a reduction of the altered lateralization for the affected hand in all three patients during MI. Furthermore, for one patient a significant improvement in the FMA score was observed, which paralleled the changes in MI and ME induced ERD.
This study demonstrates that home-based MI neurofeedback training is feasible and allows for highly intensive training regimes. The observations made are in line with the notion of an over-involvement of the ipsilateral hemisphere during activities of the affected limb. The described changes of lateralization with MI neurofeedback training encourage continuing this line of research with larger sample sizes and matched healthy controls, to see if home-based MI neurofeedback training can indeed help to shift MI- and ME-related activation towards the expected lateralization patterns.